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Jeffrey A Brinker, M.D.

Jeffrey A Brinker, M.D.

  • Professor of Medicine
  • Joint Appointment in Radiology and Radiological Science


Lastly generic effient 10 mg overnight delivery, it was a privilege to use Aloe vera on the bombing victims in the April 1995 disaster in Oklahoma City order effient without a prescription. The attendants discount effient 5 mg on line, doctors and especially the injured learned that the healing capabilities of Aloe vera far exceeded their expectations in pain control and healing time reduction. Aloe vera has an unlimited future in new applications, and I sense in dentistry we are just on the cutting edge of promising utilization for anti-inflammatory procedure, antiviral, and immunological benefits for our patients. Aloe Vera Produces Anti-Inflammatory, Immune Strengthening Effects On Skin Excerpts By Steven R. The succulent leaf of the Aloe vera plant is one of natures most revered therapeutic herbs. Historical and religious documents of the Egyptians, Romans, Greeks, Hebrews, Chinese, Indians, Algerians, Moroccans, Tunisians and Arabians report its effectiveness for both internal and external uses. Aloe vera Traditional Herbal Medicine From traditional herbal medicine, Aloe vera is reported useful for the following symptoms: fever, skin diseases, constipation, gonorrhea, jaundice, rheumatic diseases, hemorrhoids, coughs & colds, edema, sciatica, lumbago, rheumatism, retention of urine, indigestion, flatulence, abdominal tumors, carbuncles, muscle spasms during menstruation, ulcers, colitis, inflammations, vaginitis & cervicitis (used as a douche), conjunctivitis, and enlargement or inflammation of the liver, spleen & other glands. During the summer of 1967, I was hired to conduct research at the worlds first medical laser laboratory at Childrens Hospital in Cincinnati. Every day, after completing my experiments, I would go into the room where the research animals were housed to help them heal from laser burns. Aloe Vera and Skin Disorders / Burns After using several preparations, I observed that Aloe vera gel produced the most impressive healing of various skin disorders including burns, lesions and cancers. I also tested the gel on myself after an accidental laser burn, and then on a few willing patients at the laboratory. Aloe is a well-known burn remedy and is used in trauma centers in California, Illinois, New York, Texas and other states. One reason Aloe has a range of beneficial effects, even being gently rubbed onto the surface is that it has the ability to penetrate the skin. Because Aloe is a super penetrator, it is added to moisturizers and shampoos, and aftershave creams. As a super emollient and emulsifier, Aloe vera gel penetrates and moisturizes the under layers of skin. Danhof and other researchers observed that when Aloe vera is combined with other healing substances, it can help these substances penetrate the skin easily and deeply. Research shows Aloe produces an anti-aging effect on skin as strong as retinoic acid. Yet, unlike retinoic acid, the polysaccharides in Aloe vera are not irritating to skin. Aloe Vera Anti-bacterial, Anti-inflammatory, Pain-relieving Each year, everyone is exposed to more than 60,000 chemical pollutants and 200 radioactive toxins that can cause a range of severe inflammations, infections and internal and external pains. Researchers report Aloe vera to contain anti-bacterial, anti-inflammatory, and pain-relieving properties. Aloe vera gel contains ingredients that neutralize harmful, foreign skin substances. Since the earliest use of X-rays, and subsequently radio-therapy, doctors have observed that radiation can cause severe skin reactions. Any remedy that protects from severe radiation reactions works by either externally healing skin or internally stimulating various immune processes. Aloe Vera reduces Skin reactions due Radiation Numerous research studies document the effectiveness of Aloe in preventing or treating reactions to radiation. For example, emulsions of juices from Aloe were applied externally after radiation treatment to 260 human patients. Researchers claimed the emulsions were far more therapeutic than most synthetic preparations in reducing skin reactions due to irradiation. They said Aloe emulsions were recommended for preventing the development of local reactions in radiation therapy, in the treatment of dry and moist epidermitis (inflammation of the outer layers of the skin) and treating radiation burns of the second and third degrees. Interestingly, the primary active ingredients of other immune-stimulating herbs like echinacea, astragalus and Oriental mushrooms are also their polysaccharides. Like Aloe vera, the therapeutic benefits of green-lipped sea mussels, shark fin soup, and the anti-cancer effect of shark cartilage are all due to naturally occurring mucilaginous polysaccharides. Used properly for the disorders it is known to benefit, Aloe vera is a powerful healer that has been successfully employed for millennia. Effect Of Orally Consumed Aloe Vera Juice On Gastrointestinal Function In Normal Humans Excerpts By Jeffrey Bland, Ph. Linus Pauling Institute of Science & Medicine Preventive Medicine, March/April 1985 Abstract this study evaluated the effect of oral Aloe vera juice supplementation on gastric pH, stool specific gravity, protein digestion/absorption, and stool microbiology. Results indicate that supplemental oral Aloe vera juice is well tolerated by most individuals and has favorable effects upon a number of gastrointestinal parameters. A discussion of the potential role of Aloe vera juice on inflammatory bowel disorders based upon this work is presented. Introduction Members of the genus Aloe Barbadensis and Aloe vera have been used historically for medical purposes. Going back to ancient Phoenician literature, historical records chronicle the application of internal contents of the leaves of the Aloe plant for the treatment of burns, wounds, and other dermatological conditions. The pharmacological principle(s) in Aloe has been the subject of great controversy throughout this history. In recent years, individuals have extracted the Aloe plant looking for specific nutritional agents, alkaloids, sapponins, fatty acid materials, glycoproteins, or terpenoid substances that may account for its unique ability to promote healing of the dermis. This research has uniformly resulted in failure to identify the active principle in Aloe. It has been suggested that the extract of the Aloe plant promotes tissue reparation through the complex synergistic interaction of many substances, including vitamins, mineral amino acids, and other small constituent molecules that are members of the terpenoid family. Substances such as Aloe-Emodin or Aloe Resin-A have been evaluated recently from Aloe extraction concentrates as being terpenoids, characteristic of Aloe potency. A great challenge still exists to phytochemists to try to better define what the physiochemical agents in Aloe are that demonstrate activity.

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Introduction Osteomyelitis is an infection of bone sustained most commonly by bacteria cheap 10 mg effient visa, although fungalOsteomyelitis is an infection of bone sustained most commonly by bacteria purchase cheap effient on line, although fungal Osteomyelitis is an infection of bone sustained most commonly by bacteria proven 5 mg effient, although fungal etiology is rarely described, particularly in immunocompromised children [1]. According to the timeetiology is rarely described, particularly in immunocompromised children [1]. According to the etiology is rarely described, particularly in immunocompromised children [1]. According to the time period between diagnosis and symptom onset, osteomyelitis is classified as acute (<2 weeks),time period between diagnosis and symptom onset, osteomyelitis is classifled as acute (<2 weeks), period between diagnosis and symptom onset, osteomyelitis is classified as acute (<2 weeks), sub-acute (2 weeks–3 months), or chronic (>3 months). Bacteria may reach bone marrow through thesub-acute (2 weeks–3 months), or chronic (>3 months). Bacteria may reach bone marrow through sub-acute (2 weeks–3 months), or chronic (>3 months). Bacteria may reach bone marrow through the bloodstream, or spreading from nearby tissue. Infection can also be subsequent to an injury thatthe bloodstream, or spreading from nearby tissue. Infection can also be subsequent to an injury that bloodstream, or spreading from nearby tissue. Infection can also be subsequent to an injury that exposes bone to a contaminated environment [1]. The estimated incidence of acute osteomyelitis is about 8 cases per 100,000 children/year [2,3]The estimated incidence of acute osteomyelitis is about 8 cases per 100,000 children/year [2,3] the estimated incidence of acute osteomyelitis is about 8 cases per 100,000 children/year [2,3] Children under 5 years of age are affected in about 50% of the cases, with a M:F ratio of 2:1. AcuteChildren under 5 years of age are affected in about 50% of the cases, with a M:F ratio of 2:1. Acute Children under 5 years of age are affected in about 50% of the cases, with a M:F ratio of 2:1. Acute osteomyelitis is approximately two times more frequent than septic arthritis, and its incidence isosteomyelitis is approximately two times more frequent than septic arthritis, and its incidence is osteomyelitis is approximately two times more frequent than septic arthritis, and its incidence is steadily increasing. Early detection is crucialthe last 20 years while the incidence of septic arthritis remained constant. Early detection is crucial the last 20 years while the incidence of septic arthritis remained constant. Early detection is crucial given that a delay in the diagnosis of only 4 days is a risk factor for long-term sequelae (Table 1). Even if the mortality is less than 1%, permanent disabilities can occur, such as growth arrest with limb length discrepancy. Less frequently, acute osteomyelitis spreads from contiguous tissues or from direct inoculation following trauma or surgery. Diagnosis the case described is instructive in many ways: medical history, clinical flndings and treatment. Medical history is typical, since the child had both a previous upper airway infection and a previous trauma, which may be an additional risk factor for acute osteomyelitis [5,6]. During bacteremia, pathogens may reach the metaphyseal regions of bones via the nutrient arteries and their straight branches, connecting with venous sinusoids near the physis. Blood flow in this area is slow and turbulent, and bacterial may enter into the extravascular space, after passing through endothelium gaps in the metaphyseal vessels [7]. A peculiar anatomic feature occurs in children aged less than 18 months: transphyseal blood vessels exist only in this age group and may allow bacteria to reach the epiphysis from the metaphysis [7,8]. Thus, in young children, osteomyelitis originating in the metaphyseal region can spread to the epiphysis, with destruction of both. Primary hematogenous osteomyelitis most frequently involves the metaphysis of long bones, i. Multifocal forms are uncommon, and usually associated with sepsis, and occur in about 5%–7% of pediatric cases, mostly in newborns (22%) [1,3]. In the described case of osteomyelitis, the patient presented with pain, functional limitation, and elevation of inflammatory markers, but without fever. Indeed, it should be kept in mind that the absence of fever does not rule out osteomyelitis, and that the classic triad of fever, pain and increased markers of inflammation is not always present. Reduced mobility is present in about 50% of children with osteomyelitis and frequently young children may present with little more than a limp or refusal to weight bear. Extreme functional impairment with an almost complete reduction of range of motion in a joint suggests septic arthritis rather than osteomyelitis, where tenderness over a metaphyseal region of a long bone is more common. Blood cultures are positive in about 50% of the paediatric cases [16], while bone aspirates may give positive results in 70% of the cases. In a limping child the differential diagnosis should include traumatic, rheumatologic, and neoplastic diseases (Table 2). In a recent retrospective study [18] including 286 children with acute lymphoblastic leukemia, 20% had a joint-localized bone pain as presenting symptom and 17% of them were initially erroneously diagnosed to have osteomyelitis. Differential Diagnoses Reactive arthritis Juvenile arthritis Septic arthritis Trauma Cancer (osteoid osteoma, leukemia, eosinophilic granuloma, metastatic neuroblastoma, Ewings sarcoma, osteosarcoma) X-ray studies in the presented case showed an osteolytic lesion of the proximal metaphysis of the femur. Indeed, in the acute phase of the disease, X-ray sensitivity is low (43%–75%), while speciflcity is slightly higher (75%–83%) [19]. X-rays can be normal up to 14 days after the onset of symptoms, and even after two weeks, only 20% of the cases show radiographic changes. Nevertheless, performing an initial X-ray is important to rule out alternative diagnoses (i. Ultrasound scan is usually negative (sensitivity 46%–74%, speciflcity 63%–100%) and therefore has a limited use.

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Similar considerations regarding hazards and revision buy effient 10 mg on-line, excision arthroplasty cheap 10 mg effient with visa, or amputation buy 5mg effient with mastercard. Indeflnite chronic oral antimicrobial suppression and soft tissue has been surgically removed and there is no should follow regimens in Table 3 and be based on in vitro concomitant sepsis syndrome or bacteremia. Despite a signiflcant amount of basic and clinical research in this fleld, many questions pertaining to the optimal diagnostic strategies and management of these infections remain unan swered. The primary focus of these guidelines will be to provide a consensus statement that addresses selected current controversies in the diagnosis and treatment of infections involving prosthetic joints. In many situations, the panel has made recommendations based on expert opinion, realizing that the amount of data to support a speciflc recommendation is limited, and that there are diverse practice patterns which seem to be equally effective for a given clinical problem. An essential component of this therapeutic approach is the strong collaboration between all involved medical and surgical specialists (eg, orthopedic surgeons, plastic surgeons, infec tious disease specialists, general internists). The panel realizes that not all medical institutions will have the necessary resources to implement all the recommendations in these guidelines. Antimicrobials should be chosen based on in vitro susceptibility as well as patient drug allergies, intolerances, and potential drug interactions or contraindications to a specific antimicrobial. The possibility of Clostridium difficile colitis should also be discussed when using any antimicrobial. The Attributes of good guidelines include validity, reliability, repro process included a systematic weighting of the quality of the ducibility, clinical applicability, clinical flexibility, clarity, multi evidence and the grade of recommendation (Table 1)[5]. Topics on which consensus wound healing problems following prosthesis implantation, could not be reached were discussed by the panel members remote infections, current clinical symptoms, drug allergies and electronically, by teleconferences, and in person. All members intolerances, comorbid conditions, prior and current microbiolo of the panel approved the flnal draft. A diagnostic arthrocentesis should be performed in all pa tuting an actual, potential, or apparent conflict. Arthrocentesis is also advised developing products that might be affected by promulgation of in patients with a chronic painful prosthesis in whom there is the guideline. It may not be nec funding, expert testimony, and membership on company advi essary if in this situation surgery is planned and the result is not sory committees. Synovial fluid analysis should basis as to whether an individuals role should be limited as a include a total cell count and differential leukocyte count, as result of a conflict. Blood cultures for aerobic and anaerobic organisms vened to discuss potential changes. It should be performed at the time of revision lowing prosthesis implantation are classifled as delayed. Both prosthetic joint surgery, when available, if the presence of infec types of infection are believed to be acquired most often tion is in doubt based on the clinical suspicion of the surgeon during prosthesis implantation. At least 3 and optimally 5 or 6 periprosthetic intraoper have systemic symptoms such as fever and chills [4, 15]. When possible (see above), withholding antimicrobial distinguish from aseptic loosening by history and physical therapy for at least 2 weeks prior to collecting intraoperative exam. The presence of acute inflammation as seen on histo the prosthesis or a late manifestation of an infection acquired pathologic examination of the periprosthetic tissue at the time during prosthesis insertion. Hematogenous infections may of surgical debridement or prosthesis removal as deflned by the also occur early after prosthesis insertion [16]. Serial exams may be the to determine if this is the case after reviewing all the available most helpful. Infections that occur rate have been discussed at length by multiple authors [1, 4, within 1–3 months after implantation are classifled as early 21, 25, 26]. They are Intraoperative histopathological examination of the peri nonspeciflc tests and are associated with a signiflcant false prosthetic tissue has a relatively high sensitivity (>80%) and positive rate particularly immediately after prosthesis implan speciflcity (>90%) and is used to decide if revision arthroplasty tation or in patients with inflammatory arthritis [21]. There are recent data sug tive or both are negative may provide the best combination of gesting that acute inflammation is less common in infection positive and negative predictive values [21, 28–30]. Suspicion of infective endocarditis or the time that microbiology laboratories incubate periprosthetic presence of a cardiac pacemaker, for example, should also tissue specimens. The optimal duration of incubation of peri warrant the consideration of obtaining blood cultures and, prosthetic tissue specimens is unknown, but prolonged incu depending on the level of suspicion of the presence of infective bation of up to 14 days may help with pathogen isolation, endocarditis, a transesophageal echocardiogram. Novel processing submitted for cell count and differential, Gram stain, and techniques may also help with pathogen identiflcation [43]. The decision to withhold antimi and antimicrobials can be withheld prior to surgery. Sonication has been used to this cutoff is much lower than that used to suggest infection in dislodge bacteria from the surface of the prosthesis, and native joint septic arthritis. Its utility in other types of prostheses is the subject of cate-fluid culture for the diagnosis of prosthetic hip and knee ongoing research. A synovial fluid leukocyte count >27 800 infection was higher than that of culturing a single sample of cells/flL and differential of 89% polymorphonuclear neutro periprosthetic tissue, namely, 78. Thus the cell count and this technique is not validated for the isolation of fungal and its ability to predict infection must be interpreted in light of the mycobacterial organisms. The Gram stain is not routinely type of prosthesis and the time from prosthesis implantation. In Recommendations the situation of a positive Gram stain and negative tissue cul 17. Rapid diagnostic tests such as polymer thesis without a sinus tract who are within approximately 30 ase chain reaction are still not yet available for routine clinical days of prosthesis implantation or fewer than 3 weeks of onset application [48–50]. The panel believes that in selected circumstances, joint pain can be the result of occult infection or other non more than one 2-stage exchanges can be successful if the flrst infectious etiologies. There may be a greater risk of interpretation of these specimens) [21, 36–38, 53].

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A partial thickness burn involves epidermis and dermis at varying depths cheap effient 5mg visa, and a full thickness burn involves epidermis buy discount effient 10 mg online, dermis purchase effient no prescription, and at times deeper tissues. Electrical burns may cause considerable damage to deeper tissues by direct effect and by occlusion of blood vessels. The severity of damage is related to the temperature to which the area was exposed, the duration of exposure, and the thickness of the skin involved. Summary of Essential Features and Diagnostic Criteria Pain with the appropriate time course following burns. Differential Diagnosis Possibly hysterical conversion pain or pain of psychological origin may prolong or exacerbate the original effects of the injury. Start: gradual emergence intermittent at first, as mild diffuse ache or unpleasant feeling, increasing to a definite pain part of the time. Pain Quality: dull ache, usually does not throb; severe during exacerbations, often or almost always with throbbing. Occurrence and Duration: most days per week, usually every day for most of the day. Precipitants and Exacerbating Factors: emotional stress, anxiety and depression, physical exercise, alcohol. Associated Symptoms Many patients have anxiety, depression, irritability, or more than one of these combined. Signs Muscle tenderness occurs but may also be found in other conditions and in normal individuals. Relief Resolution or treatment of emotional problems, anxiety, or depression often diminishes symptoms. Anxiolytics may help but should be avoided since some patients become depressed and others develop dependence. Differential Diagnosis From delusional and conversion pains; from muscle spasm provoked by local disease; and from other causes of dysfunction in particular regions, e. X7b Note: b coding used to allow the a coding to be employed if an acute syndrome needs to be specified. Main Features Prevalence: rare; estimated to be present in less than 2% of patients with chronic pain without lesions. Age of Onset: not apparently reported in children; onset in late adolescence or at any time in adult life. Pain Quality: may be sensory or affective or both, not necessarily bizarre; essential characteristic is attribution of the pain by the patient to a specific delusional cause, e. Associated Symptoms and Modifying Factors May be exacerbated by psychological stress, relieved by treatment causing remission of illness. Complications In accordance with causal condition; usually lasts for a few weeks in manic-depressive or schizo-affective psychoses, may be sustained for months or years in established schizophrenia if resistant to treatment. Occasionally chronic pain without any formal delusions remits to be succeeded by a paranoid or schizophrenic psychosis. Social and Physical Disabilities In accordance with the mental state and its consequences. Essential Features Those required for diagnosis are pain, without a lesion or overt physical mechanism and founded upon a delusional or hallucinatory state. Differential Diagnosis From undisclosed or missed lesions in psychotic patients, or migraine, giving rise to delusional misinterpretations; from tension headaches; from hysterical, hypochondriacal, or conversion states. X9a Note: X = to be completed individually according to circumstances in each case. Site May be symmetrical; if lateralized, possibly more often on the left precordium, genitals; may be at any single point over the cranium or face, can involve tongue or oral cavity or any other body region. Frequency increases from general practice populations to specialized headache or pain clinics or psychiatric departments. Estimates of 11% and 43% have been found in psychiatric departments, depending on the sample. Sex Ratio: estimated female to male ratio 2:1 or greater-particularly if multiple complaints occur. Onset: may be at any time from childhood onward but most often in late adolescence. Pain Quality: described mostly in simple sensory terms, but complex or affective descriptions occur in some cases. Time Pattern: Pain is usually continuous throughout most of the waking hours but fluctuates somewhat in intensity, does not wake the patient from sleep. Associated Symptoms Loss of function without a physical basis (anesthesia, paralyses, etc. There may be frequent visits to physicians to obtain relief despite medical reassurance, or excessive use of analgesics as well as other psychotropic drugs for complaints of depression, neither type of remedy proving effective. Psychological interpretations are frequently not acceptable to the patient, although emotional conflict may have provoked the condition. The personality is often of a dependent-histrionic-labile type (hysterical personality or passive dependent personality). The first is largely monosymptomatic, is relatively rare, and consists of patients who have pain in one or two regions only, who have only recently developed pain, and who have clear evidence of emotional conflicts, perhaps with an associated paralysis or anesthesia, and a relatively good prognosis. Some patients who primarily have a depressive illness also present with pain as the main somatic symptom. Their pain may be interpreted delusionally or may be based on a tension pain, etc. The second type is of patients with more numerous or multiple complaints, often of many and varied types without a physical basis. In the history these often number more than 10, including classical conversion or pseudoneurological symptoms (paralyses, weakness, impairment of special senses, difficulty in swallowing, etc.

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The particle size is large enough to allow the Sn colloid to remain >99% within the injected joint discount effient uk, and yet is small enough to be readily engulfed by the inflammatory synovial macrophages purchase 5mg effient free shipping. A commercial Sn colloid formulation was well characterized with a validated shelf-life of 2 weeks and is finalizing a trial of dogs with naturally occurring elbow arthritis [476] purchase effient. It is composed of a homogeneous mixture of a defined chemical composition and can be manufactured from a large variety of starting materials, both natural and synthetic, and by many different preparation techniques. Depending upon the method of preparation and starting materials, a wide variety of particles or microspheres in terms of size, size distribution, composition, surface chemistry, topography and morphology can be obtained. While microspheres are completely spherical and homogeneous in size, particles less homogeneous in size and shape are generally termed microspheres as well. Depending on the preparation method and material used, microspheres show a typical size distribution which often deviates from the mono-sized ideal [185]. The selection of an appropriate method for the preparation of particles depends on the size of required particles and physicochemical characteristics. In this chapter, the method used for the preparation of particles include: fl Precipitation; fl Emulsion: fl Evaporation or extraction of solvent; fl Sol-gel; fl Spray-Drying; and fl Electro spraying processes. The techniques, principle, advantages and disadvantages of each preparation method are also the point of discussion. In precipitation method, the precursors used are mostly inorganic salts (nitrate, chloride, sulphate, etc. The solution is then subjected to pH adjustment and precipitated by the addition of precipitating reagents, usually hydroxides, carbonates, oxalates or citrates etc. Precipitation and their aggregation are influenced by the concentration of salt, temperature, the actual pH and the rate of pH change. In actual practice, the precipitate is heated to the required temperature in appropriate atmosphere to undergo condensation. Precipitation reactions involve the simultaneous occurrence of nucleation, growth, coarsening, and/or agglomeration processes. Nucleation is the formation within a super-saturated solution of the smallest particles of a precipitate (nuclei) capable of spontaneous growth. If the precipitation is carried out in such a manner as to produce numerous nuclei, precipitation will be rapid, individual crystals will be small, filtration and washing difficult, and purity low. On the other hand, if precipitation is carried out so that only a few nuclei are formed, precipitation will be slower, crystals larger, filtration easier, and purity higher. Hence, control of nucleation processes is of considerable significance in precipitation. Once the crystal nuclei are formed, crystal growth proceeds through diffusion of the ions to the surface of the growing crystal and deposition of those ions on the surface. This crystal growth continues until super-saturation of the precipitating material is eliminated and equilibrium solubility is attained. The reactions tend to exhibit the following characteristics: fl the products of precipitation reactions are generally sparingly soluble species formed under conditions of high super saturation; fl Such conditions dictate that nucleation will be a key step of the precipitation process and that a large number of small particles will be formed; 57 fl Secondary processes, such as the Ostwald ripening and aggregation, will dramatically affect the size, morphology, and properties of the products; and fl the super-saturation conditions necessary to induce precipitation are usually the result of a chemical reaction. Schematic illustration of the precipitation process Precipitations are generally carried out from dilute solutions adding the precipitant slowly with some form of agitation to a hot solution. Normally, the precipitant is then allowed to age before it is removed by filtration and washed. Due to the seemed necessity to avail particles of desired sizes, these precipitates are subsequently calcined at appropriate temperatures, cooled and sieved to obtain the final product. Each precipitation reaction requires its own precursor and precipitating reagent and at the same time each precipitation process requires to control the concentration of the solution, pH, temperature and stirring speed of the mixture in order to obtain the final product with required properties. Few commonly used steps that dictate the success of precipitation are: fl Taking appropriate stoichiometric amounts of starting materials; fl Making appropriate amount of solution of optimum pH; fl Maintaining optimum pH of the precipitation solution; and fl Performing filtration to remove water, undesired ions and impurities. A precipitation process should satisfy the following three main requirements: (1) Quantitative precipitation is a desirable proposition; (2) the precipitate formed should be amenable for filtration and should not creep; and (3) the precipitate should be obtained from known purity. Solubility of the larger crystals is less than that of smaller crystals due to exposure of less surface area to the solution. Gradual addition of dilute solution of the precipitant, with stirring, to a medium is desirable. Concentration of Ions and Solubility of Solids: the rate of precipitation not only depends on the concentration of ions in solution, but also on the solubility of the solids formed during the equilibrium process. While a solution containing an optimal concentration of ions sufficient to form a precipitate will slow down the process, it is advantageous owing to the ability to form larger crystals of lower solubility. Temperature: While precipitation at elevated temperatures is a desirable proposition to slow down the nucleation and crystal growth due to the increased thermal motion of the particles in solution, increase in solubility of the precipitate at elevated temperature is an impediment that reduces the precipitate yield. Digestion: Digestion is a process which involves heating the solid and mother liquor for a certain period of time. During digestion, the small crystals dissolve and larger crystals grow (Ostwald ripening). Digestion also reduces impurities (occluded ions) effectively as the process reduces the surface area for adsorption of foreign ions owing to the recrystallization of the small crystals and growth of larger crystals. During the process of digestion, impurities are replaced by the common ions that properly fit the crystal lattice. Solvent: the polarity of the solvent affects the solubility of an ionic solid (precipitate) in the solvent. Addition of other miscible solvent in the solution is avoided as it would alter the polarity. The polarity of water is reduced by the addition of alcohols, thereby reducing the solubility of precipitates. Common-ion concentration: Addition of the reagent exploiting the common ion effect for the complete precipitation of a particular ion of a sparingly soluble salt having a low value of solubility product is a practice routine. However, in some cases, excess presence of common ions increases the solubility of the precipitate by decreasing the activity of the ions in solution, as they become more concentrated in solution and deviate from ideal behaviour. Stirring: Stirring the solution during precipitation is desirable as it increases the motion of particles in solution and decreases the localized build-up of concentration of ions.


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