NaOH Standardization and Titration of an Unknown Organic Acid Essay Example for Free

NaOH Standardization and Titration of an Unknown Organic Acid Essay NaOH Standardization and Titration of an Unknown Organic Acid Overview: Methods for counting the number of molecules in a sample is a major emphasis of laboratory work. In this experiment we will use the method of titration to count the number of acid molecules in a solution. Measuring mass is a relatively easy procedure to do in the lab (although a balance is expensive). Counting the number of particles requires more effort. Molecular counting can be done by setting an unknown amount of a substance equal to a known amount of substance. In the titration we will perform in lab this week, you will add OH ions to solution until they are equivalent to the number of H+ ions in solution. The point at which this mole equivalency occurs is known as the equivalence point. An indicator in the solution will change color to signal that the equivalence has been reached (actually, the indicator responds to the slightest excess of OH ions). The color change in a titration is called the endpoint. At the equivalence point of the titration, the moles of OH (base) are equivalent to the moles of H+ (acid) in the sample. The moles of OH added to the solution from a buret are calculated from the concentration of the base (MOH) and the volume of base (VOH) added, as: V (L) n (mol) Lmol MOH OH OH The lab goal is to determine the molar mass of an unknown monoprotic acid. The grams of acid are determined from weighing the acid and the moles are determined from the titration with NaOH. Because it is a monoprotic acid, the moles of acid are equal to the moles of OH at the endpoint of the titration. n (mol) n (mol) OH acid Standardization of NaOH: Last week in lab you prepared a NaOH solution with an approximate concentration of 0.1 M. The first task is to determine the exact concentration of that solution by titrating the NaOH against a known amount of acid. The known amount of acid you will use comes from dissolving the solid acid potassium hydrogen phthalate (KHP, FW = 204.2212 g/mol) in 25 mL of H2O. KHP is a large organic molecule, but can be viewed simply as a monoprotic acid. The titration of the KHP with NaOH can be express by the chemical reaction: OH (aq) + KHP(aq) H2O + KP (aq) To standardize (determine the concentration of) your NaOH solution Lmol you will measure volume of NaOH required to reach the titration endpoint. At the equivalence point the moles of NaOH are equivalent to the moles of KHP titrated. n (mol) n (mol) NaOH KHP .Before you titrate a KHP sample, begin with a practice titration of 25 mL of a 0.1 M HCl solution with your NaOH. A  practice titration is a good way to begin any titration. It lets you know the approximate concentration of your NaOH solution and the behavior of the indicator at the endpoint. Prepare a buret with your NaOH solution. Recall how you clean the buret first with DI water and then rinse the buret with about 10 mL of your NaOH solution. Drain the rinse NaOH into a large waste beaker at your lab bench. Finally, fill your buret with NaOH,. Be sure to fill the tip of the buret before you use it and make sure there are no bubbles in the tip. With your graduated cylinder measure approximately 25 mL of 0.1M HCl. Record the exact volume you use. Add the HCl to an erlenmyer flask and add three drops of phenolphthalein indicator. Titrate the acid solution with the NaOH. Place the erlenmyer flask under the buret on a white sheet of paper (or towel). Remember to make an initial volume reading before you begin. You should need nearly the same volume of base as you have acid for this titration, because the molarities of each are similar. You can titrate quickly at first, but as you get near the endpoint slow your titrating. Small amounts of titrant can be added by quickly rotating the buret stopcock one revolution as you approach the end point. Even smaller quantities of a single drop can be added as you approach the end point. Remember this is only practice. Don t spend a lot of time on this step. After you have reached the endpoint, the lightest pink color that will persist for 20 seconds, show this solution to your TA. Anything past light pink indicates a solution with excess OH and you will be over counting the moles of acid in solution. After this practice titration, refill your buret, dump your titrated solution down the drain, and rinse your glassware with DI water. Standardization of NaOH with KHP: Prepare a solution with a known number of moles of acid, by weighing exactly, approximately 0.5 grams of the solid acid KHP in a weigh boat. (Do not add KHP to the weigh boat while on the balance!) Add the weighed acid to a large erlenmyer flask. If any of the KHP remains on the weigh boat use your squirt bottle to rinse all of the KHP into the erlenmyer flask. Dissolve the acid in approximately 30 mL of water the exact amount does not matter. Add four drops of phenolphthalein indicator. Titrate the KHP acid solution with the NaOH. Place the erlenmyer flask under the buret on a white sheet of paper (or towel). Remember to make an initial volume reading before you begin. If not all of the KHP is dissolved, you can still begin the titration. Just make sure that all the  KHP is dissolved before you reach the titration endpoint. The first titration is always the most difficult because you do not know how carefully you need to add the titrant. In this case, you should be able to add 15 mL of NaOH without passing the endpoint. As you are adding your initial amounts of NaOH,notice the pink color of the indicator right as the NaOH enters the solution. As the pink color begins to persist, slow the titration down. Do not let the buret go below 50 mL during the titration. If you get close to 50 mL, stop the titration, record the volume of the buret and then refill the buret and continue to titrate. The end point of the titration occurs when the solution is the lightest pink color that will persist for 20 seconds. It is very likely that you will overshoot the endpoint on your first try. Don t let this worry you. Record the final volume on the buret. At the equivalence point, you have added the exact number of moles of OH as there were moles of acid initially. The moles of acid (monoprotic) you can determine from the mass of the acid and its molar mass (KHP = 204.2212 g/mol). Before you continue, calculate the approximate concentration of your NaOH solution. Perform a second titration of KHP with NaOH. Weigh and dissolve another 0.5 g sample of KHP and dissolve it in a clean erlenmyer flask. The flask can be wet inside. Why can the Erlenmyer flask be wet when sample is added, but the buret must be carefully rinsed with the solution that will eventually be dispensed? Refill your buret with NaOH and titrate the new KHP sample to its pink endpoint. Do not forget to make an intial buret reading, add indicator and not go past 50 mL on the buret. After the titration, calculate the concentration (molarity) of your NaOH solution. Titrate a third KHP sample with the intent of obtaining a third measurement of your NaOH solution concentration. After tititrating the third sample, calculate the NaOH concentration and compare all three calculations of the NaOH concentrations. If the three measurements of the concentration are the same to within 0.02 M, you may conclude that the concentration of your NaOH is the average of these three measurements. If you have accomplished this precision in your standardization of NaOH, continue to the titration on an unknown acid. If any of the measured NaOH concentrations are more than 0.02 M, you should perform a fourth standardization titration, using another 0.5 g sample of KHP. After examining the four concentration of NaOH, determine if any one concentration is suspect as either too large or too small. You  can do this by inspection. However, there are statistical tests (Student T-tests) that will calculate if a data point is an outlier. If we ever team teach this course with Math140 we will use the student T-test at this point. For now, if three concentrations are within 0.02 M then average these three concentrations as the NaOH concentration. If you still don t have three measurements within 0.02 M of each other, perform a fifth standardization with a new sample of KHP. Obtain the NaOH concentration from the fifth titration and average all five measurements to obtain an average NaOH concentration.Titration of an Unknown Acid to Determine Molar Mass: The units of molar mass are g/mol. This intensive property is the ratio of two extensive properties, as is shown in the figure below. To determine the molar mass of your unknown acid, you will perform the titration of the unknown acid in the same way you performed the titration of KHP. Obtain from your TA an unknown acid sample vial. Write your unknown number in your notebook. This sample vial contains two samples of your unknown acid. Weigh the vial and all its contents. Add half of the acid to a clean erlenmyer flask. Reweigh the sample vial to determine how much acid you will be titrating in Trial # 1. Note: There are only two samples of your unknown available. Exercise caution while titrating. Treating the unknown acid in the same way as the KHP sample, titrate to the endpoint and calculate the moles of NaOH require to reach the endpoint. From the mass and mole measurements of the unknown acid, determine the molar mass of the unknown acid. Clean your glassware and repeat the titrtation on the second sample of unknown acid. To report the molar mass of the acid, take an average of the two molar mass measurements. Report the uncertainty as half of the difference between the two mass measurements (ex. if Trial # 1 gives a mass of 240 g/mol and Tiral # 2 gives 256 g/mol the average should be reported as 248 8 g/mol). Before you leave the lab, clean your buret with distilled water then place it upside down in the buret clamp with the stopcock open. All solutions can be placed down the sink. Return your unknown vial to your TA. Finally, turn in your blue notebook pages

Water fluoridation

Water fluoridation ABSTRACT The safety and efficacy of water fluoridation has been a topic of great controversy throughout Americas communities. Scientific evidence has shown that ingesting low to moderate levels of fluoride can benefit the dental health of a community, especially those populations in a community that may be classified as having low socioeconomic status. Children in all areas, but especially those with low SES, are at greatest risk for developing dental caries and having a community water fluoridation program (CWFP) will help them reduce their dental caries. Moderation of fluoride ingestion for individuals is the key. Low to moderate daily ingestion of fluoride, averaging 1.0 mg/liter per day is optimum. Dental and skeletal fluorosis can occur if ingestion levels are greater than 3.0 mg/liter per day for long periods of time. This is a discussion on the safety and efficacy of water fluoridation. INTRODUCTION This commentary presents the on-going controversy on community water fluoridation in the United States, and I will attempt to analyze science-based evidence in support of water fluoridation. There have always been questions on the safety and efficacy of fluoride in drinking water, some school of thought believes that fluoridation has some adverse effects to exposed human populations, especially in infants and children. Another school of thought believes that water fluoridation is essential in preventing tooth decay, and therefore the practice should be sustained. According to the Center for Disease Control and prevention (CDC) water fluoridation is one of the 10 great public health achievements of the 20th century in the United States (CDC, 1999), which is attributable for increased lifespan of Americans by 25 years ( Bunker et al., 1994). This paper will discuss science-based evidence that proves the efficacy and safety of water fluoridation among children as well as offer some reco mmendations to the various stakeholders. POSITION STATEMENT Water fluoridation is the adjustment of the concentration level to the optimally regulated level of which the naturally occurring fluoride presents in public or community drinking water supplies. In most cases, deflouridation is needed when the naturally occurring fluoride level exceeds recommended limits. The recommended fluoride concentration in drinking water by the U.S. Public Health Service (PHS) is 0.7-1.2mg/L, to effectively prevent dental caries and minimize the occurrence of dental fluorosis (NRC, 2006). Low decay rates were found to be associated with continuous use of water with fluoride content of 1ppm (Meskin, 1995). There has been serious questions as to the efficacy of fluoride intervention in preventing both tooth decay, as it benefit is said to be merely cosmetic or topical (CDC, 1999). Such topical effect of fluoride can be achieved by the use tooth without the risking the overexposure from ingested fluoride (NRC, 2006). However, it has also been reported that fluor ide exposure provides both systemic and topical protection. Ingested fluoride deposited on tooth surface during tooth formation, and fluoride contained in saliva provides long-lasting systemic protection against booth tooth decay than topical application using tooth paste or fluoride foams (CDC, 2001). WHAT IS FLUORIDE Fluoride is a naturally occurring element. It is found in rocks and soil everywhere. Fluoride can be found in fresh water and ocean water. Naturally occurring fluoride levels ranges from 0.1ppm to over 12ppm (NRC, 2006).Fluoride is present in the customary diets of people and in most portable water sources. The average dietary intake of fluoride is approximately 0.5mg daily from either naturally occurring fluoride in the water or the fluoride found in produce. It is also a normal component of tooth enamel and bone studies have shown that the calcified tissues of both enamel and bone are made up of a combination of hydroxyl- and fluor-apatites of varying composition depending on the abundance of fluoride at the site of formation. These tissues are the principal sites of deposition of fluoride (NRC, 2006). HOW FLUORIDE PREVENTS AND CONTROLS DENTAL CARIES Dental caries is an infectious, transmissible disease in which bacterial by-products (i.e., acids) dissolve the hard surfaces of teeth. Unchecked, the bacteria can penetrate the dissolved surface, attack the underlying dentin, and reach the soft pulp tissue. Dental caries can result in loss of tooth structure, pain, and tooth loss and can progress to acute systemic infection. Cryogenic bacteria (i.e., bacteria that cause dental caries) reside in dental plaque, a sticky organic matrix of bacteria, food debris, dead mucosal cells, and salivary components that adheres to tooth enamel. Plaque also contains minerals, primarily calcium and phosphorus, as well as proteins, polysaccharides, carbohydrates, and lipids. Cryogenic bacteria colonize on tooth surfaces and produce polysaccharides that enhance adherence of the plaque to enamel. Left undisturbed, plaque will grow and harbor increasing numbers of cryogenic bacteria. An initial step in the formation of a carious lesion takes place when cryogenic bacteria in dental plaque metabolize a substrate from the diet (e.g., sugars and other fermentable carbohydrates) and the acid produced as a metabolic by-product demineralizes (i.e., begins to dissolve) the adjacent enamel crystal surface (CDC,2009). Demineralization involves the loss of calcium, phosphate, and carbonate. These minerals can be captured by surrounding plaque and be available for reuptake by the enamel surface. Fluoride, when present in the mouth, is also retained and concentrated in plaque. Fluoride works to control early dental caries in several ways. Fluoride concentrated in plaque and saliva inhibits the demineralization of sound enamel and enhances the remineralization (i.e., recovery) of demineralized enamel (Featherstone, 1999 Koulourides, 1990). As cryogenic bacteria metabolize carbohydrates and produce acid, fluoride is released from dental plaque in response to lowered pH at the tooth-plaque interface. The released fluoride and the fluoride present in saliva are then taken up, along with calcium and phosphate, by de-mineralized enamel to establish an improved enamel crystal structure. This improved structure is more acid resistant and contains more fluoride and less carbonate (Featherstone, 1999). Fluoride is more readily taken up by demineralized enamel than by sound enamel. Cycles of demineralization and remineralization continue throughout the lifetime of the tooth. Fluoride also inhibits dental caries by affecting the activity of cryogenic bacteria. As fluoride concentrates in dental plaque, it inhibits the process by which cryogenic bacteria metabolize carbohydrates to produce acid and affects bacterial production of adhesive polysaccharides. In laboratory studies, when a low concentration of fluoride is constantly present, one type of cryogenic bacteria, Streptococcus mutans, produces less acid. Whether this reduced acid production reduces the carcinogenicity of these bacteria in humans is unclear (Van Loveren, 1990). Saliva is a major carrier of topical fluoride. The concentration of fluoride in ductal saliva, as it is secreted from salivary glands, is low approximately 0.016 parts per million (ppm) in areas where drinking water is fluoridated and 0.006ppm in non fluoridated areas. This concentration of fluoride is not likely to affect cryogenic activity. However, drinking fluoridated water, brushing with fluoride toothpaste, or using other fluoride dental products can raise the concentration of fluoride in saliva present in the mouth 100- to 1,000-fold. The concentration returns to previous levels within 12 hours but, during this time, saliva serves as an important source of fluoride for concentration in plaque and for tooth remineralization (Murray,1993). Applying fluoride gel or other products containing a high concentration of fluoride to the teeth leaves a temporary layer of calcium fluoride-like material on the enamel surface. The fluoride in this material is released when the pH drops in the mouth in response to acid production and is available to remineralize enamel. In the earliest days of fluoride research, investigators hypothesized that fluoride affects enamel and inhibits dental caries only when incorporated into developing dental enamel (i.e., preeruptively, before the tooth erupts into the mouth) (Murray,1993). Evidence supports this hypothesis, but distinguishing a true preeruptive effect after teeth erupt into a mouth where topical fluoride exposure occurs regularly is difficult. However, a high fluoride concentration in sound enamel cannot alone explain the marked reduction in dental caries that fluoride produces . The prevalence of dental caries in a population is not inversely related to the concentration of fluoride in enamel, and a higher concentration of enamel fluoride is not necessarily more efficacious in preventing dental caries (Mcdonagh etal.,2000). The laboratory and epidemiologic research that has led to the better understanding of how fluoride prevents dental caries indicates that fluorides predominant effect is post eruptive and topical and that the effect depends on fluoride being in the right amount in the right place at the right time. Fluoride works primarily after teeth have erupted, especially when small amounts are maintained constantly in the mouth, specifically in dental plaque and saliva (Mcdonagh etal., 2000). Thus, adults also benefit from fluoride, rather than only children, as was previously assumed. RISK FOR DENTAL CARIES The prevalence and severity of dental caries in the United States have decreased substantially during the preceding 3 decades. National surveys have reported that the prevalence of any dental caries among children aged 1217 years declined from 90.4% in 19711974 to 67% in 19881991; severity (measured as the mean number of decayed, missing, or filled teeth) declined from 6.2 to 2.8 during this period (Burt, 1989). These decreases in caries prevalence and severity have been uneven across the general population; the burden of disease now is concentrated among certain groups and persons. For example, 80% of the dental caries in permanent teeth of U.S. children aged 517 years occurs among 25% of those children. Populations believed to be at increased risk for dental caries are those with low socioeconomic status (SES) or low levels of parental education, those who do not seek regular dental care, and those without dental insurance or access to dental services (Meskin,1995). Persons can be at high risk for dental caries even if they do not have these recognized factors. Children and adults who are at low risk for dental caries can maintain that status through frequent exposure to small amounts of fluoride (e.g., drinking fluoridated water and using fluoride toothpaste). Children and adults at high risk for dental caries might benefit from additional exposure to fluoride (e.g., mouth rinse, dietary supplements, and professionally applied products). All available information on risk factors should be considered before a group or person is identified as being at low or high risk for dental caries. However, when classification is uncertain, treating a person as high risk is prudent until further information or experience allows a more accurate assessment. This assumption increases the immediate cost of caries prevention or treatment and might increase the risk for enamel fluorosis for children aged NATIONAL GUIDELINES FOR FLUORIDE USE PHS recommendations for fluoride use include an optimally adjusted concentration of fluoride in community drinking water to maximize caries prevention and limit enamel fluorosis. This concentration ranges from 0.7ppm to 1.2ppm depending on the average maximum daily air temperature of the area (PHS, 1991). In 1991, PHS also issued policy and research recommendations for fluoride use. The U.S. Environmental Protection Agency (EPA), which is responsible for the safety and quality of drinking water in the United States, sets a maximum allowable limit for fluoride in community drinking water at 4ppm and a secondary limit (i.e., non-enforceable guideline) at 2ppm (EPA,1998). The U.S. Food and Drug Administration (FDA) is responsible for approving prescription and over-the-counter fluoride products marketed in the United States and for setting standards for labeling bottled water and over-the-counter fluoride products (e.g., toothpaste and mouth rinse) (ADA,2007). Nonfederal agencies also have published guidelines on fluoride use. The American Dental Association (ADA) reviews fluoride products for caries prevention through its voluntary Seal of Acceptance program; accepted products are listed in the ADA Guide to Dental Therapeutics (ADA, 2007). A dosage schedule for fluoride supplements for infants and children aged 16 years, which is scaled to the fluoride concentration in the community drinking water, has been jointly recommended by ADA, the American Academy of Pediatric Dentistry (AAPD), and the American Academy of Pediatrics (AAP) (Meskin,1995). In 1997, the Institute of Medicine published age-specific recommendations for total dietary intake of fluoride. These recommendations list adequate intake to prevent dental caries and tolerable upper intake, defined as a level unlikely to pose risk for adverse effects in almost all persons. COST-EFFECTIVENESS OF FLUORIDE MODALITIES Documented effectiveness is the most basic requirement for providing a health-care service and an important prerequisite for preventive services (e.g., caries-preventive modalities). However, effectiveness alone is not a sufficient reason to initiate a service. Other factors, including cost, must be considered. A modality is more cost-effective when deemed a less expensive way, from among competing alternatives, of meeting a stated objective (Garcia,1989). In public health planning, determination of the most cost-effective alternative for prevention is essential to using scarce resources efficiently. Dental-insurance carriers are also interested in cost-effectiveness so they can help purchasers use funds efficiently. Because half of dental expenditures are out of pocket (Garcia, 1989), this topic interests patients and their dentists as well. Potential improvement to quality of life is also a consideration. The contribution of a healthy dentition to quality of life at any age has not been quantified, but is probably valued by most persons. Although solid data on the cost-effectiveness of fluoride modalities alone and in combination are needed, this information is scarce. In 1989, the Cost Effectiveness of Caries Prevention in Dental Public Health workshop, which was attended by health economists, epidemiologists, and dental public health professionals, attempted to assess the cost-effectiveness of caries-preventive approaches available in the United States (Downer et al., 1981). Community Water Fluoridation Health economists at the 1989 workshop on cost-effectiveness of caries prevention calculated that the average annual cost of water fluoridation in the United States was $0.51 per person (range: $0.12$5.41) (Burt, 1989). In 1999 dollars, this cost would be $0.72 per person (range: $0.17$7.62). Factors reported to influence the per capita cost included: size of the community (the larger the population reached, the lower the per capita cost); number of fluoride injection points in the water supply system; amount and type of system feeder and monitoring equipment used; amount and type of fluoride chemical used, its price, and its costs of transportation and storage; and expertise of personnel at the water plant. When the effects of caries are repaired, the price of the restoration is based on the number of tooth surfaces affected. A tooth can have caries at >1 location (i.e., surface), so the number of surfaces saved is a more appropriate measure in calculating cost-effectiveness than the number of teeth with caries. The 1989 workshop participants concluded that water fluoridation is one of the few public health measures that results in true cost savings (i.e., the measure saves more money than it costs to operate); in the United States, water fluoridation cost an estimated average of $3.35 per carious surface saved ($4.71 in 1999 dollars). Even under the least favorable assumptions in 1989 (i.e., cities with populations A Scottish study conducted in 1980 reported that community water fluoridation resulted in a 49% saving in dental treatment costs for children aged 45 years and a 54% saving for children aged 1112 years (Downer et al., 1981). These savings were maintained even after the secular decline in the prevalence of dental caries was recognized. The effect of community water fluoridation on the costs of dental care for adults is less clear. This topic cannot be fully explored until the generations who grew up drinking optimally fluoridated water are older. School Water Fluoridation Costs for school water fluoridation are similar to those of any public water supply system serving a small population (i.e., Assessment of the Adverse Health Effects of fluoride Evidence of the adverse health effects of prolonged exposure to high concentrations of fluoride are well documented by several peer reviewed studies, which are examined in this paper. Higher concentrations of total ingested fluoride from potential sources like drinking water, food and beverages, dental-hygiene products such as toothpaste, and pesticide residues can have adverse health effects on humans (NRC, 2006). Some of the adverse health effects of fluoride in drinking water are enamel fluorosis, skeletal fluorosis, bone cancer and bone fracture. (NRC, 2006, PHS, 1991). Fluorosis is caused mainly by the ingestion of fluoride in drinking water (Viswanathan et al., 2009). Fluoride has high binding affinity for developing enamel and as such high concentration of cumulative fluoride during tooth formation can lead to enamel fluorosis, a dental condition from mild to severe form characterized by brown stains, enamel loss and surface pitting (DenBesten Thariani, 1992). These dental ef fects are believed to be caused by the effects of fluoride on the breakdown rates of early-secreted matrix proteins, and on the rates at which the degraded by-products are withdrawn from the maturing enamel (Aoba Fejerskov, 2002). Children are much more at risk of enamel fluorosis, especially in their critical period from 6 to 8 years of age, than adults. Fluoride uptake into enamel is possible only as a result of concomitant enamel dissolution, such as caries development (Fejerskov, Larsen, Richards, Baelum, 1994). There is a 10% prevalence of enamel fluorosis among U.S. children in communities with water fluoride concentrations at or near the EPAs MCLG of 4 mg/L (NRC, 2006). The CDC estimates that 32% of U.S. children are diagnosed with dental fluorosis (CDC, 2005). Today, there are convincing evidence that enamel fluorosis is a toxic effect of fluoride intake, and that its severe forms can produce adverse dental effects, and not just adverse cosmetic effects in humans (NRC, 200 6). Burt and Eklund (1999) states: â€Å"The most severe forms of fluorosis manifest as heavily stained, pitted, and friable enamel that can result in loss of dental function†. Epidemiological data from both observational and clinical studies have been examined. Sowers, Whitford, Clark Jannausch (2005) investigated prospectively for four years bone fracture in relation to fluoride concentrations in drinking water in a cohort study, by measuring serum fluoride concentrations and bone density of the hip, radius, and spine. The authors reported higher serum fluoride concentrations in the communities with fluoride concentrations at 4 mg/L in drinking water; and higher osteoporotic fracture rates in the high fluoride areas that were similar to those in their previous studies in 1986 and 1991. It is unclear in their recent study whether existing factors in the population like smoking rates, hormone replacement and physical activity were examined as potential cofounders for fractures. Fasting serum fluoride concentrations are considered a good measure of long-term exposure and of bone fluoride concentrations (Whitford, 1994; Clarkson et al., 2000). Findings by t he Sowers studies were complemented in several ways by Li et al. (2001) in a retrospective cohort ecologic study. The combined findings of Sowers et al. (2005) and Li et al., (2001) lend support to the biological gradients of exposures and fracture risk between 1 and 4 mg/L of fluoride concentration. Evidently, the physiological effect of fluoride on â€Å"bone quality† and the fractures observed in the referenced animal studies are consistent with the effects found in the observational studies. RECOMMENDATIONS Before promoting a fluoride modality or combination of modalities, the dental-care or other health-care provider must consider a persons or groups risk for dental caries, current use of other fluoride sources, and potential for enamel fluorosis. Although these recommendations are based on assessments of caries risk as low or high, the health-care provider might also differentiate among patients at high risk and provide more intensive interventions as needed. Also, a risk category can change over time; the type and frequency of preventive interventions should be adjusted accordingly. Continue and Extend Fluoridation of Community Drinking Water Community water fluoridation is a safe, effective, and inexpensive way to prevent dental caries. This modality benefits persons in all age groups and of all SES, including those difficult to reach through other public health programs and private dental care (CDC, 2001a). Community water fluoridation also is the most cost-effective way to prevent tooth decay among populations living in areas with adequate community water supply systems. Continuation of community water fluoridation for these populations and its adoption in additional U.S. communities are the foundation for sound caries-prevention programs. In contrast, the appropriateness of fluoridating stand-alone water systems that supply individual schools is limited. Widespread use of fluoride toothpaste, availability of other fluoride modalities that can be delivered in the school setting, and the current environment of low caries prevalence limit the appropriateness of fluoridating school drinking water at 4.5 times the optimal concentration for community drinking water. Decisions to initiate or continue school fluoridation programs should be based on an assessment of present caries risk in the target school(s), alternative preventive modalities that might be available, and periodic evaluation of program effectiveness (CDC, 2001a). Frequently Use Small Amounts of Fluoride All persons should receive frequent exposure to small amounts of fluoride, which minimizes dental caries by inhibiting demineralization of tooth enamel and facilitating tooth remineralization. This exposure can be readily accomplished by drinking water with an optimal fluoride concentration and brushing with fluoride toothpaste twice daily(CDC, 2001a). Supervise Use of Fluoride Toothpaste among Children Aged Childrens teeth should be cleaned daily from the time the teeth erupt in the mouth. Parents and caregivers should consult a dentist or other health-care provider before introducing a child aged Use an Alternative Source of Water for Children Aged 8 Years Whose Primary Drinking Water Contains >2 ppm Fluoride In some regions in the United States, community water supply systems and home wells contain a natural concentration of fluoride >2ppm. At this concentration, children aged 8 years are at increased risk for developing enamel fluorosis, including the moderate and severe forms, and should have an alternative source of drinking water, preferably one containing fluoride at an optimal concentration. In areas where community water supply systems contain >2ppm but 8 years. For families receiving water from home wells, testing is necessary to determine the natural fluoride concentration (CDC, 2001a). Label the Fluoride Concentration of Bottled Water Producers of bottled water should label the fluoride concentration of their products. Such labeling will allow consumers to make informed decisions and dentists, dental hygienists, and other health-care professionals to appropriately advise patients regarding fluoride intake and use of fluoride products (CDC, 2001). CONCLUDING POSITION STATEMENT When used appropriately, fluoride is a safe and effective agent that can be used to prevent and control dental caries. Fluoride has contributed profoundly to the improved dental health of persons in the United States and other countries. Fluoride is needed regularly throughout life to protect teeth against tooth decay. To ensure additional gains in oral health, water fluoridation should be extended to additional communities, and fluoride toothpaste should be used widely. Adoption of these and other recommendations in this paper could lead to considerable savings in public and private resources without compromising fluorides substantial benefit of improved dental health. What is consistent from the literature review is the fact that infants and children are much more at risk of overexposure and the development of adverse health effects. A community water fluoridation program (CWFP) is very safe and efficient, not only in terms of reducing dental caries, but also on the communitys budg et (CDC, 2001a). A CWFP can especially help those communities who have populations in the low SES category. These populations have children whose parents or guardians dont always have access to dental insurance and so regular dental checkups to curb the dental caries is not always an option. Reducing dental caries before they lead into more extreme oral morbidity can be very beneficial to these children. Implementing a fluoridated water program can also be beneficial to a whole community in terms of saving communities thousands and millions of dollars. Implementing a water program would follow strict guidelines set by the EPA, so the optimum level of fluoride would be followed, staying in the range of 0.7 to 1.2, where people would ingest no more than an average of 1 mg/liter of fluoride per day. Moderation is the key. There are studies confirming that ingestion of fluoride greater than the optimum level could produce dental fluorosis. Though unconfirmed by studies, individual reports have even suggested that ingestion of fluoride >8 mg/liter per day over a long period of time could produce skeletal fluorosis. However, with proper surveillance and reporting of fluoride in water systems, the greater population could be served, increasing the dental health of all individuals, especially the youth and saving dollars from excessive health care costs (ADA, 2009). Remember, a little prevention now can go a long way later. REFERENCES ADA (2005).Fluoridation Facts: ADA statement commemorating the 60th anniversary of community water fluoridation. Retrieved October 19, 2009 from www.ada.org/public/topics/fluoride/facts/fluoridation_facts.pdf ADA.(2007). ADA Guidelines to Dental Therapeutics. Retrieved October 23, 2009 from http://www.ada.org/prof/resources/pubs/advocacy.asp ADA (2009). Fluoride: Natures tooth decay fighter. J of the Am. Dental Ass., 140(1), 126-126. Alphajoh, C.(2009). (PhD Student). Service Learning Activity: Environmental Health. Walden University. Assessed November 13, 2009 from http://environmentalhealthtoday.wordpress.com/2009/05/13/commentary-and-position-statement-on-the-safety-and-efficacy-of-water-fluoridation/ Aoba, T., Fejerskov, O. (2002). Dental fluorosis: Chemistry and biology. Crit. Rev. Oral. Biol. Med., 13(2), 155-170. Bowden, G.(1990). Effects of fluoride on the microbial ecology of dental plaque. J Dent Res 1990; 69(special issue):653—9 Brunelle, J.(1987. The prevalence of dental fluorosis in U.S. children. J Dent Res.(Special issue) 68:995. Bunker, J.P., Frazier, H.S., Mosteller, F. (1994). Improving health: measuring effects of medical care. Milbank Quarterly,72, 225-58. Burt, B. (1989).(Ed.). Proceedings for the workshop: Cost-effectiveness of caries prevention in dental public health, Ann Arbor, Michigan, May 1719, 1989. J Public Health Dent 1989; 49(special issue):3317. Burt, B.A., Eklund, S.A. (1999). Dentistry, dental practice, and the community. Philadelphia, Pennsylvania: WB Saunders Company, 204-20. CDC (1999). Ten great public health achievements United States, 1900 1999. MMWR,48(12), 214-243. CDC (2001a). Promoting oral health: intervention for preventing dental caries, oral and pharyngeal cancers and sport-related craniofacial injuries a report on recommendations of the Task Force on Community Preventive Services. MMWR 2001, 50(21), 1-12. CDC. (2001). Recommendations for using fluorideto prevent and control dental

The Start of Islam Essay -- Islam Muslim Religion

The Start of Islam   Ã‚  Ã‚  Ã‚  Ã‚  Out of the many interesting religions of the Far East Islam has quite a uniqueness to it. The name, Islam stems from the word â€Å"salam,† that means peace. The word â€Å"Muslim,† which means a follower of Islam, refers to a person who submits him or her self to the will of God. Many religious experts believe that the prophet Muhammad founded Islam in the year 622 CE. Muhammad was believed to have lived from 570-632 CE. This particular religion started when the angel Jibreel read the first revelation to Muhammad. We know already that the followers of Islam are called Muslims. The Muslims believe in the â€Å"one true God,† which they call Allah.   Ã‚  Ã‚  Ã‚  Ã‚  Muhammad was born in the year 570 CE. When he was growing up, he was sent into the desert in order for a roster family to raise him. The young Muhammad was orphaned when he was 6 years old but brought up by his uncle. While Muhammad was young, he worked mostly as a shepherd. Later on in his youth, he was given the job of being a camel driver on the trade routes between Syria and Arabia. Throughout his travel, he meat many people of different religious beliefs. Muhammad was able to observe members of Christianity, Pagan, and Judaism religions. After Muhammad married, there was more time for meditation for him. Supposedly, at or around the age of forty, the angel Gabriel (Jibreel) visited him while he was in Mecca. From then on he believed that he had been ordained a prophet by Gabriel, and that his concern was co...

Felicia Hemans and To My Own Portrait versus William Wordsworth and Tin

Visions of the Past: Felicia Hemans & William Wordsworth I will here attempt to give an idea of the links between Felicia Hemans and William Wordsworth. I will begin with a brief biography of Hemans, followed by a look at the relationship between Hemans and Wordsworth. I will end with a short comparison of Hemans' poem "To My Own Portrait" and "Tintern Abbey." Hemans' Biography [1] Born Felicia Dorothea Browne in Liverpool in 1793 and raised in North Wales, Hemans was largely home-schooled by her mother. Considered a child prodigy by her family, she loved Shakespeare, was well read in several languages, and is said to have been able to quote passages from literature at length after only one reading. Felicia also studied music and drawing, and was later to include several of her sketches as frontispieces for her publications. She began writing as early as the age of eight, and her first volume, Poems was published by subscription in 1808 when she was only 14. The collection was met with some harsh reviews, which, although upsetting to the young poet, did not lessen her passion for writing. In fact, the same year saw the publication of England and Spain, or Valour and Patriotism. This volume was likely inspired by the service of her elder brothers, who both entered the army at an early age, and served in the Peninsular Campaigns in Spain. As her sister Anne Brown e was later to write in her posthumous biography of Hemans, "trumpets and banners now floated through her dreams in which birds and flowers had once reigned paramount." [2] Felicia's father left his wife and children in 1810 to move to Upper Canada, effectively ending all contact with his family. By this time Felicia was engaged in correspondence with Captain Alfre... ... V. 1. Hemans' Life and Works, 1839. P. 26 4. Hemans, Felicia. Quoted by Anne Browne. "Memoir of Mrs. Hemans." V. 1. Hemans' Life and Works, 1839. P. 251 5. Byron, Lord. From a letter to the Hon. Douglas Kinnaird, September 17th, 1820. Byron: A Self-Portrait, Letters and Diaries 1798-1824. V. II. London: John Murray, 1950. 6. Jeffrey, Lord. Edinburgh Review. October, 1829. 7. The information for this section is taken from two sources: Wolfson, Susan & Peter Manning. The Longman Anthology of British Literature: The Romantics and Their Contemporaries. V. 2A. New York: Longman, 1999. Kennedy, Deborah. "Hemans, Wordsworth, and the 'Literary Lady.'" Victorian Poetry. 35:3 Fall 1997. 267-286. 8. Quoted in Kennedy, p. 268. 9. Quoted in Kennedy, p. 270. 10. Kennedy, p. 270. 11. Quoted in Kennedy, p. 273. 12. Longman Anthology, p. 736.

The Definition of Independence :: Definition Essays

  Ã‚  Ã‚  Ã‚  Ã‚   Some people say that the definition of independence is a complex word and idea to try to define. In al truth independence is a perplexing word to try to define. This is because everybody has their own speculations of what independence is. Very infrequently are their two people that have the same perception of what the definition of independence is. What I perceive the definition of independence is the absolute freedom to do what you want, and to not be held back by any rules or laws of government or man, but by the rules and laws of nature and your own self concise. My view of independence may greatly differ form your beliefs on the definition but in this paper I will try to show exactly what my perspective on the definition of independence is by my experiences, my beliefs, my thoughts, and research on the subject at hand.   Ã‚  Ã‚  Ã‚  Ã‚  In my beliefs independence can not be the definition of what your government says is independent. For if you go by what the government says is independent than why not go by Chinas definition of independence, or by the communists party’s definition of independence. If you go by any governments definition of independence than you are not truly going to be independent. For each governments definition of independence you are not truly independent. In my belief to be truly independent you must be able to do what you want when you want and have nobody to say that you cant do that. If the government is telling you that you can do this and not do that then how can you have independence. The only true way to have independence is to make decisions based on you and not based on what society thinks. How can a person be truly independent if they have to do what other people think is the right thing to do? The answer to that question is that they can not be independent for independence is the ability to do what you want even if it is not what society thinks that it is not the right thing to do. These beliefs is one of my building blocks for my definition of independence.   Ã‚  Ã‚  Ã‚  Ã‚  In my experience I have only had the feeling of true independence once or twice in my life. I felt this felling when I am by myself and nothing is around you but woods, waterfalls or complete silence.

Analysis of Robert Frost’s “An Old Man’s Winter Night” Essay

What is the goal in a poem? Why do writers write? Most poems are an attempt to pass on a message, to give a moral, or in any case, to communicate in one way or another. An example of a writer doing this in a poem may be seen in An Old Man’s Winter Night, by Robert Frost. Robert Frost (1874-1963) wrote An Old Man’s Winter Night, perhaps his most well conceived work and published it in the book ‘Mountain Interval’, released in 1920 as a fine peak to his career. The poem tells the story of the last night before an old man’s death. This man is portrayed as being lonely, and without meaning to anyone except for himself. The old man seems to realize this in a certain point in the poem, and decides that he no longer wants to live. He then goes to sleep, however soon after he is disturbed by the shifting of a log. He then shifts, as the log did, and dies seemingly without pain, â€Å"still sleeping† as Frost says. The poem appears to have a message to transmit, which can be unveiled through some close reading. There are several reasons which convince the reader that An Old Man’s Winter Night is memorable, impressive, and effectively passes on a moral. Firstly, the reader is engaged into the scene with no information about the old man, which parallels the old man’s situation, as neither does he know how he has become what he is: â€Å"What kept him from remembering what it was / That brought him to that creaking room was age.† Perhaps this was done to make the reader just as lost as the old man and able to enter more deeply into the old man’s character, thus being able to sympathize better with him. The old man seems to be lacking any interest in a long life and apparently has no real social life. This lack of friends is what draws us to feel for the man who clearly was not cared for in life, either due to a refusal to care for others, or because other unjustly neglected him. The man’s meaningless existence is accentuated by him constantly scaring away what seems to frighten him or makes him uncomfortable. However, the old man seems to be apathetic towards his own state. The fact that he does not even know how he got to be so in the first place adds to this notion, and makes him seem detached from his own situation. Another factor which makes the emptiness more apparent is the â€Å"barrels round him†. One may wonder: â€Å"What is in these barrels?† As Frost does not tell us what they are, we may assume that they are empty barrels, much like the life of the man. Another factor  which adds to the void of the man’s life is that the author uses possessive adjectives showing that the snow on the roof is â€Å"his† and that the icicles hanging along the wall are â€Å"his†. The reader may assume that there must be an enormous lack of subsistence to the man’s life for Frost to tell us that these completely insignificant matters are possessed by him. Overall, the reader pities the old man for his seemingly lonely, purportless, and depressing existence. Secondly, in An Old Man’s Winter Night, Frost has artistically created metaphors with light which are overflowing with meanings that can easily be missed and yet help in drawing the poem together with a sense of cohesion. â€Å"What kept his eyes from giving back the gaze / Was the lamp tilted near them in his hand.† This helps one to understand the way the man is feeling, albeit it in a minor way and in turn aids one in working out what he is doing. He is not sitting idly, but has a lamp, therefore is not trying to sleep. We are not instructed further as to what he is attempting to do but it clearly requires thought. He cannot cope with this mental surge as his age has drawn senility, â€Å"What kept him from remembering what it was / That brought him to that creaking room was age.† Frost tells us early in the poem that he was light â€Å"to no one but himself.† This informs us that he is the only one that is in touch with himself and his existence. This light he is to himself and the light he holds in his hand work together to make his isolation even more apparent, because the light that he holds is making him unable to see the outside. For him to be able to see outside he could simply have tilted the light towards the window, yet, one may understand that this metaphor shows that he is either unwilling to open up to others, or is afraid of what he may then see. He may have been intimidated by the out of doors which â€Å"looked darkly in at him†. This continues with the idea that he was only a light to himself because in tilting the light towards himself, he sees his reflection in the window rather than what may have been beyond the window. However, had he illuminated them so that he could see outside, they would no longer be darkly looking in at him. Frost then writes: â€Å"A quiet light, and then not even that.† One may speculate from this line that Frost is telling us that even the old man has lost touch with himself, and no longer cares about his own existence. Frost may possibly be calling our  attention to this line with the eye-rhyme between â€Å"what† and â€Å"that†. In the next few lines, the old man dies: â€Å"The log that shifted with a jolt / Once in the stove, disturbed him and he shifted, / And eased his heavy breathing, but still slept.† Perhaps the log shifting, breaking, and going out represented his light permanently going out as well. This link may be made with the repetition of the word â€Å"shifted†; the log shifts, and then the man shifts. In these lines there is also alliteration with the words â€Å"still slept†. Frost may have been drawing our attention to this to be sure that the death of the old man would have a strong impact on the reader. These lines are impressive and effective at expressing the death of the old man, and leave the reader feeling sorry for him. Thirdly, one may appreciate how clear the final moral is of the poem. â€Å"One aged man — one man — can’t keep a house, / A farm, a countryside, or if he can, / It’s thus he does it of a winter night.† Frost generalizes the situation, by broadening â€Å"one aged man† to â€Å"one man†. He resumes the whole story, giving the reader a clear moral at the end, identifiable to all thanks to the generalization. One may believe that, ultimately, Frost is trying to show one how not to end up, and how not to die, but offers no insight as to the better way of ending the spell one spends on Earth. Perhaps he is telling us to make sure that we do not end up like this man, and that we should â€Å"tilt the light† towards others instead of ourselves, and therefore to be in touch with others. Furthermore, it is telling us that if we do not open up towards others, and if we stay inside our own shell, with our icicles on the walls and our snow on top, isolating us from the outside world, that we shall end up in solitude and be a light to no one but ourselves, just like the old man. It may be out of context to wonder if this poem relates to the poet in any way, but it does seem rather in depth for any imagination. However, as Robert Frost was not a particularly lonely man, perhaps he was expressing a great fear of his brought forth by an incident in his surroundings. As one may now see, there are several aspects of the poem which make An Old Man’s Winter Night memorable and effective in transmitting the author’s message. These aspects are: the reader is engaged into the scene with no  information about the old man; metaphors which Frost has made with light are overflowing with many meanings; one may appreciate how clear the poem is fairly clear thanks to the generalization and how the whole of the poem thoroughly contributes to the moral. This poem transmits its idea superbly and majestically making its goal of communication accomplished.

Crisis Management Communication Plan Essay

Create a 750- to 1,050-word crisis management communication plan for a health care organization or health care setting with which you are familiar. Include the following in your plan:  · An explanation of how communication dynamics may differ in times of crisis, mass trauma, or disaster  · Three ways to reduce stress during a crisis  · Three ways to resolve potential communication challenges Cite at least two peer-reviewed references supporting the strategies used in your communication plan. College life is much different than life at home. Your parents aren’t there to help whenever you need them and you’ll be entrusted with far more responsibility than you’re used to. Make sure you stay organized and manage your time wisely or you’ll find yourself drowning in your new found responsibilities. There is HCS 350 Week 5 Crisis Management Communication Plan in this pack. General Questions – General General Questions Resource: Assignment Grading Criteria: Crisis Management Plan Create a 750- to 1,050-word crisis management communication plan for a health care organization or health care setting with which you are familiar. Include the following in your plan:  · An explanation of how communication dynamics may differ in times of crisis, mass trauma, or disaster  · Three ways to reduce stress during a crisis  · Three ways to resolve potential communication challenges Cite at least two peer-reviewed references supporting the strategies used in your communication plan. College life is much different than life at home. Your parents aren’t there to help whenever you need them and †¦ Search for more tutorials here – https://bitly.com/12CbKhM College life is much different than life at home. Your parents aren’t there to help whenever you need them and you’ll be entrusted with far more responsibility than you’re used to. Make sure you stay organized and manage your time wisely or you’ll find yourself drowning in your new found responsibilities. General Questions – General General Questions Resource: Assignment Grading Criteria: Crisis Management Plan Create a 750- to 1,050-word crisis management communication plan for a health care organization or health care setting with which you are familiar. Include the following in your plan:  · An explanation of how communication dynamics may differ in times of crisis, mass trauma, or disaster  · Three ways to reduce stress during a crisis  · Three ways to resolve potential communication challenges Cite at least two peer-reviewed references supporting the strategies used in your communication plan.