Use Of Fluorine Research Articles

A review: advancements in fluoro-based polymers for aggrandizing anti-galling and wear resistant characteristics

Galling is the surface phenomenon which involves adhesion of local contact points and creation of protrusions on the juxtaposition of surfaces owing to high friction, inappropriate tribological loading, starved lubrication and high contact pressure (~ 1000 kPa). All these factors result in severe plastic deformation varying from 8000 to 10,000 µe (e-strain) and diffusion of materials into one another, which consequently results in fatigue wear, surface roughness, tribocorrosion and seizing up of critical parts. The aim of the review is to analyze and summarizes the issue of galling, concurrently it also deals with the novel and economical mitigation method i.e. use of fluorine based coatings e.g. PTFE, owing to their lowest friction coefficient from 0.02 to 0.2 among other solids, high stiffness, high thermal stability and non-adherent characteristics that augments the mechanical and tribological properties and concurrently protect against hostile environments that eventually upsurges the life of components.

Synthesis and Optimization of Kv7 (KCNQ) Potassium Channel Agonists: The Role of Fluorines in Potency and Selectivity.

Based on the potent Kv7 agonist RL-81, we prepared new lead structures with greatly improved selectivity for Kv7.2/Kv7.3 over related potassium channels, i.e., Kv7.3/Kv7.5, Kv7.4, and Kv7.4/7.5. RL-36 and RL-12 maintain an agonist EC2x of ca. 1 μM on Kv7.2/Kv7.3 in a high-throughput assay on an automated electrophysiology platform in HEK293 cells but lack activity on Kv7.3/Kv7.5, Kv7.4, and Kv7.4/7.5, resulting in a selectivity index SI > 10. RL-56 is remarkably potent, EC2x 0.11 ± 0.02 μM, and still shows an SI = 2.5. We also identified analogues with significant selectivity for Kv7.4/Kv7.5 over Kv7.2/Kv7.3. The extensive use of fluorine in iterative core structure modifications highlights the versatility of these substituents, including F, CF3, and SF5, to span orders of magnitude of potency and selectivity in medicinal chemistry lead optimizations.

Computational Fluorine Scanning Using Free-Energy Perturbation.

We present perturbative fluorine scanning, a computational fluorine scanning approach using free-energy perturbation. This method can be applied to molecular dynamics simulations of a single compound and make predictions for the best binders out of numerous fluorinated analogues. We tested the method on nine test systems: renin, DPP4, menin, P38, factor Xa, CDK2, AKT, JAK2, and androgen receptor. The predictions were in excellent agreement with more rigorous alchemical free-energy calculations and in good agreement with experimental data for most of the test systems. However, the agreement with experiment was very poor in some of the test systems, and this highlights the need for improved force fields in addition to accurate treatment of tautomeric and protonation states. The method is of particular interest due to the wide use of fluorine in medicinal chemistry to improve binding affinity and ADME properties. The promising results on this test case suggest that perturbative fluorine scanning will be a useful addition to the available arsenal of free-energy methods.

Enamel remineralization and repair results of Biomimetic Hydroxyapatite toothpaste on deciduous teeth: an effective option to fluoride toothpaste

BackgroundDental caries is a recognized worldwide public health problem. Despite being one of the most effective strategies against dental caries, the excessive use of fluorine may result in a potential risk of developing dental fluorosis especially in children under age of six. The purpose of this work is to analyze a fluorine-free toothpaste containing Biomimetic Hydroxyapatite to assess enamel re-mineralizing and repairing properties.ResultsThe study was performed in vitro and in vivo, comparing the hydroxyapatite toothpaste with two others toothpaste containing different fluorine concentrations. The coating effect of the micro-structured Hydroxyapatite nanoparticles reintegrates the enamel with a biomimetic film reproducing the structure and the morphology of the biologic Hydroxyapatite of the enamel. As demonstrated, the coating is due to the deposit of a new layer of apatite, which presents fewer particles than the natural enamel, not based on the chemical—physical changes occurring in fluorinated toothpastes. Moreover, it shows resistance to brushing as a consequence of chemical bonds between the synthetic and natural crystals of the enamel.ConclusionsThe use of Biomimetic Hydroxyapatite toothpastes has proven to be a valuable prevention measure against dental caries in primary dentition since it prevents the risk of fluorosis.

Forensic Aspects of Fluorine Poisoning

In medical literature, existing studies show the opportunity to use fluorine for one�s health. The presence of this substance in the normal composition of all tissues and organs of the human body as well as deficiencies highlighted under certain circumstances support this aspect. They show both the positive effects of fluorine, such as the role of fluorine in increased calcium storing in the bones and teeth, and the negative effects, for example inhibition of phosphatases, (enzymes used in many metabolic processes). The double effect also appears in the use of fluorine in treatments, because when overcoming a critical threshold for the body it may produce adverse effects, sometimes leading to death. The present article analyzes these effects, the primary purpose being to raise awareness and identify the reactions of fluorine on the body.

SU58STRESS VARIABLES AND METHYLATION OF THE DDR1 GENE IN EARLY INTERVENTION PSYCHOTIC PATIENTS

The 19F nucleus has a complex role in vivo, particularly when it comes to in vivo imaging applications—ironically, endogenous fluorine is nearly invisible to imaging techniques despite its relatively high concentrations. This has been exploited in recent years with the increasing popularity of 19F magnetic resonance imaging (MRI), as the in vivo images are background free. 19F MRI has particular advantages when it comes to modern personalized medicine applications, such as cell therapies. However, fluorine has specific chemical properties that can complicate in vivo use. Moreover, high signal-to-noise ratio, within reasonable imaging time, is challenging. In this chapter, we will focus on the use of fluorine for MRI, particularly in cell-tracking applications and cardiac applications, covering this imaging modality from basic principle to the first clinical trial. Finally, we will briefly discuss other modalities of in vivo imaging using fluorine, such as 18F positron emission tomography and ultrasound imaging with perfluorocarbon gases.

Tuning the photoluminescence of graphene oxide quantum dots by photochemical fluorination

Tailoring the band gap and understanding the underlying mechanism are important for extending the applications of graphene quantum dots in optoelectronics. In this work, we synthesize fluorinated graphene oxide quantum dots (F-GOQDs) through a photochemical method, and study their optical properties. The obtained F-GOQDs exhibit a maximal blue-shift of photoluminescence (PL) emission of ca. 77 nm compared to that of the graphene oxide quantum dots (GOQDs). The PL shift results from the substitution of the hydroxyls and carbonyls groups with fluorine during the fluorination process, which can tune the band gap of the GOQDs. Density functional theory (DFT) calculations support our proposed mechanism for band gap tuning in the GOQDs through the use of fluorination.

Asbestos treatment technologies

The use of asbestos was banned because of the carcinogenic properties of its fibres, but asbestos-containing wastes are still present in great amounts. They are currently landfilled or encapsulated with resins, but these approaches led to the release of fibres in the environment. Hence, the destruction of asbestos fibres is now regarded as a preferable option. This study aims at reviewing the currently available technologies for the destruction of asbestos fibres, considering thermal, chemical and mechanochemical processes. The considered thermal treatments include both standard vitrification and thermal treatments with controlled recrystallization. Advantages and applications of the addition of other inorganic materials are described, and the use of microwaves and oxyhydrogen as heat carrier are discussed in full details. The best practices for chemical treatments based on strong acidic or basic solutions are reported, as well as the use of fluorine. This study also investigates the reaction of asbestos with reducing agents in the self-propagating high-temperature syntheses and the use of supercritical water in a hydrothermal treatment. Mechanochemical processes such as high-energy milling are also reviewed. A comparison is given in terms of energy costs, consumption of chemicals, emissions and final use of obtained byproducts.

P‐15: The Use of Fluorination to Enhance the Performance and the Reliability of Elevated‐Metal Metal‐Oxide Thin‐Film Transistors

The effects of fluorination on elevated‐metal metal‐oxide (EMMO) thin‐film transistors (TFT) were investigated. Attributed to the effective passivation of defects in the metal oxide, both the scalability and the reliability were enhanced on fluorinated indium‐gallium‐zinc oxide (IGZO) and indium‐tin‐zinc oxide (ITZO) EMMO TFTs.

Widely Applicable Hydrofluorination of Alkenes via Bifunctional Activation of Hydrogen Fluoride.

Expanding the use of fluorine in pharmaceuticals, agrochemicals and materials requires a widely applicable and more efficient protocol for the preparation of fluorinated compounds. We have developed a new generation nucleophilic fluorination reagent, KHSO4-13HF, HF 68 wt/wt %, that is not only easily handled and inexpensive but also capable of hydrofluorinating diverse, highly functionalized alkenes, including natural products. The high efficiency observed in this reaction hinges on the activation of HF using a highly “acidic” hydrogen bond acceptor.

WAYS OF PROCESSING AND RECYCLING OF FLUORINE-CONTAINING WASTE OF ALUMINUM INDUSTRY

The information on aluminum metal production volume, its application areas and ecological problems which go with aluminum production are described. The data on fluorine containing waste products types and quantity at aluminum production were reported. The aluminum production waste products negative influence on environment was identified. For hydrogen fluoride production the use of fluorine containing waste products as alternative man-made raw material is offered. Resource effective and resource saving method of aluminum production fluorine containing waste products processing is described in detail. Processing method consists waste oxidizing calcining to move away carbon component, interaction of sulfuric acid with fluorine containing particles to product hydrogen fluoride, dissolution of solid sulphatisation product and aluminum hydroxide precipitation. Aluminum oxide and sodium sulfate can be byproducts of describing wastes processing method. Aluminum oxide can be used for production run of aluminum metal electrolytic production. Sodium sulfate can be used in glass and cellulose production, in textile and tanning industries. The thermodynamic calculations of fluorine containing wastes components with sulfuric acid chemical interaction are given. The research of kinetics of fluorine containing wastes with sulfuric acid chemical interaction by method of reacting mixture unstoppable weighing with mass auto-registration have been carried out. The dependence of transformation (reaction) degree on the time in temperature range of 220 to 260 ºС has been identified. It was characterized by Krank-Gistling-Braunstein equation. On obtained dependence the reaction area and process rate-limiting step was determined. The methods of intensification of aluminum industry fluorine containing wastes interaction process in observed temperature range has been offered. The economic and ecologic effect of aluminum industry fluorine containing wastes processing method has been established.Forcitation:Petlin I.V., Lesnikova M.S. Ways of processing and recycling of fluorine-containing waste of aluminum industry. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 4. P. 108-113.

The Use of Fluorine to Protect β-Solidifying γ-TiAl-Based Alloys against High-Temperature Oxidation

ABSTRACTLight-weight alloys based on intermetallic titanium aluminides (TiAl) are structural materials considered for high-temperature applications, e.g. in aero engines or automotive engines. TiAl alloys of engineering interest consist of two phases, the γ-TiAl and the α2-Ti3Al-phase. Recent developments have led to the so-called TNM alloys (T = TiAl; N = Nb; M = Mo) with an Al-content of 43.5 at.%. These alloys also possess the disordered body centered cubic β-Ti(Al)-phase at elevated temperatures, which ensures a better hot-workability compared to conventional two-phase alloys. However, the relatively low Al content (< 45 at.%) limits the high-temperature capability due to reduced oxidation resistance. This impedes their application in a temperature range above 800°C. The present work shows how the fluorine effect counteracts this disadvantage due to the formation of a protective alumina layer. The performance of the TNM alloy with the nominal composition of Ti-43.5Al-4Nb-1Mo-0.1B (at.%) is compared with another TNM alloy variant containing additional elements, such as Si and C, and the so-called GE alloy (Ti-48Al-2Cr-2Nb; at.%), which is already in use for turbine blades. The results of isothermal and thermocyclic high-temperature exposure tests of untreated and fluorine treated specimens will be compared. The effect of composition and microstructure of the alloys on the oxidation behavior with and without fluorine treatment are discussed.

Development of the composition and technology of a caries preventive gel

Prevention of dental caries involves remineralization of the tooth surfaces with calcium and phosphorus medicines, but the use of fluorine- containing remedies in the form of a cream, gel and varnish is more effective. The aim of our work was to substantiate the composition and technology of a gel with cetylpyridinium hexafluorosilicate having the caries preventive action. A gelling agent – hydroxyethyl cellulose that provides stability and the essential structural and mechanical properties of the gel has been selected experimentally. Microscopic studies have substantiated introduction of the solubilizer PEG-40 hydrogenated castor oil in the concentration of 0.5% that promotes dissolution of the peppermint essential oil with preserving the gel transparency. The use of 10% sorbitol has been substantiated to provide the moderate osmotic properties and to prevent the gel drying. Microbiological studies have shown the necessity of using sodium benzoate as a preservative in the concentration of 0.3%. The temperature regimen of cetylpyridinium hexafluorosilicate introduction in the composition of the gel base has been substantiated by thermogravimetric studies. The technology of gel has been developed.

Ultrasonic Treatment to Molten FEM©™ Aluminum Alloy and Effects of Ultrasound Treatment Melt Temperature on Hardness

Today, in the industry of aluminum, the D. C. casting of billets and slabs is playing the major role. The producers of these slabs and billets are many. The end users of the product are OEMs. The degassing technology for producing these aluminum slabs and billets is provided by very few. There are two types of degassing methods currently in use. One of these, vacuum degassing, is used primarily in the steel industry and thus not generally used in the aluminum industry. The second method, generally employed in the aluminum industry, is rotary degassing, which uses finely dispersed argon, chlorine, fluorine to remove dissolved hydrogen and various salts from melt. The challenges associated with producing aluminum are reducing porosity due to hydrogen precipitation during casting through degassing processes; which generates detrimental effects on mechanical properties of alloy castings and removing impurities like; the Ca, Mg salts etc. from the molten metal. Looking at the degassing systems provided by these players, are going to be obsolete as the environment norms will become stricter in the next decade, because of the use of Fluorine and Chlorine for removing the Ca, Mg, etc. impurities from the molten metal as the ozone layer is getting depleted and process becomes more cumbersome and hazardous. So, the innovation in the technology is needed; which leads research interest on development of the ultrasonic degassing as a better option. During this research authors would be using ultrasonic technology over existing technology to compare the results of conventional degasser units available in the market such as LARSTM, SNIFTM, STASTM - ACDTM, AlpurTM, MDUTM etc., and would be finding out the better operating parameters of ultrasonic equipment for the process for replacement of Fluorine and Chlorine based old technology with Ultrasonic Technology. This research paper should underpin improvement in the process and hence improved hardness of material by elimination of the fluorine and chlorine usage by replacing it with ultrasonic technology with suitable mechanical design, metallurgical criteria and thermal analysis consideration. During the entire research and development authors had carried out various operations like Research on thermal and metallurgical behavior of the molten metal and alloys, Comparison of results achieved using ultrasonic technique over existing technique, Formulation of conclusion; making ultrasonic technique a proven technology, and Identifying the further scope of research and development. With the experiments carried out, authors found significant improvement in hardness of the material produced by ultrasonic degassing as compared with the hardness of material produced by conventional degassing.

Ultrasonic Treatment to Molten FEM©™ Aluminum Alloy and Effects of Ultrasound Treatment Melt Temperature on Porosity

Today, in the industry of aluminum, the D. C. casting of billets and slabs is playing the major role. The producers of these slabs and billets are many. The end users of the product are OEMs. The degassing technology for producing these aluminum slabs and billets is provided by very few. There are two types of degassing methods currently in use. One of these, vacuum degassing, is used primarily in the steel industry and thus not generally used in the aluminum industry. The second method, generally employed in the aluminum industry, is rotary degassing, which uses finely dispersed argon, chlorine, fluorine to remove dissolved hydrogen and various salts from melt. The challenges associated with producing aluminum are reducing porosity due to hydrogen precipitation during casting through degassing processes; which generates detrimental effects on mechanical properties of alloy castings and removing impurities like; the Ca, Mg salts etc. from the molten metal. Looking at the degassing systems provided by these players, are going to be obsolete as the environment norms will become stricter in the next decade, because of the use of Fluorine and Chlorine for removing the Ca, Mg, etc. impurities from the molten metal as the ozone layer is getting depleted and process becomes more cumbersome and hazardous. So, the innovation in the technology is needed; which leads research interest on development of the ultrasonic degassing as a better option. During this research authors would be using ultrasonic technology over existing technology to compare the results of conventional degasser units available in the market such as LARSTM, SNIFTM, STASTM - ACDTM, AlpurTM, MDUTM etc., and would be finding out the better operating parameters of ultrasonic equipment for the process for replacement of Fluorine and Chlorine based old technology with Ultrasonic Technology. This research paper should underpin improvement in the process and hence improved hardness of material by elimination of the fluorine and chlorine usage by replacing it with ultrasonic technology with suitable mechanical design, metallurgical criteria and thermal analysis consideration. During the entire research and development authors had carried out various operations like Research on thermal and metallurgical behavior of the molten metal and alloys, Comparison of results achieved using ultrasonic technique over existing technique, Formulation of conclusion; making ultrasonic technique a proven technology, and Identifying the further scope of research and development. With the experiments carried out, authors found significant improvement in hardness of the material produced by ultrasonic degassing as compared with the hardness of material produced by conventional degassing.

Conhecimento de alunos do Curso de Odontologia sobre o uso racional do flúor

INTRODUÇÃO: O uso do flúor sob a forma de fluoreto é o principal fator de proteção no controle da cárie dentária, em todo o mundo. O flúor pode ser oferecido à população de diversas formas, sendo as mais utilizadas a fluoretação da água de abastecimento e os dentifrícios fluoretados. Entretanto, a exposição ao flúor também pode ocorrer por meio das soluções para bochechos; de géis e materiais de uso odontológico, e da dieta, por meio de alimentos e bebidas industrializados. OBJETIVO: Este estudo objetivou verificar o conhecimento dos alunos de diferentes semestres do curso de Odontologia da Universidade Estadual do Sudoeste da Bahia sobre o uso racional do flúor. MATERIAL E MÉTODO: Realizou-se um estudo transversal, sendo a amostra composta por acadêmicos de diferentes semestres do curso de Odontologia, que responderam a um questionário para verificar seus conhecimentos em relação ao flúor. RESULTADO: Dos acadêmicos entrevistados, 58,16% consideraram o alto risco à cárie e a hipersensibilidade dentinária como os principais fatores para a indicação do flúor. Para 64,29%, o gel foi o produto fluoretado mais indicado na sua prática diária, e 67,35% indicaram o dentifrício fluoretado para crianças com idade superior a seis anos. Parte significativa da amostra afirmou saber sobre a presença de flúor em alimentos industrializados (91,84%) e reconhecer que o flúor é tóxico (93,88%). CONCLUSÃO: Apesar das informações sobre flúor adquiridas no decorrer do curso, expressiva parte dos alunos ainda não possui domínio sobre o assunto e mostrou-se insegura para poder recomendá-lo na sua prática clínica diária.

Fluorine in medicinal chemistry.

Since its first use in the steroid field in the late 1950s, the use of fluorine in medicinal chemistry has become commonplace, with the small electronegative fluorine atom being a key part of the medicinal chemist's repertoire of substitutions used to modulate all aspects of molecular properties including potency, physical chemistry and pharmacokinetics. This review will highlight the special nature of fluorine, drawing from a survey of marketed fluorinated pharmaceuticals and the medicinal chemistry literature, to illustrate key concepts exploited by medicinal chemists in their attempts to optimize drug molecules. Some of the potential pitfalls in the use of fluorine will also be highlighted.

Acute Post-Streptococcal Glomerulonephritis in Children – A Review

Acute post-streptococcal glomerulonephritis (APSGN) is characterized by abrupt onset of hematuria, edema, hypertension, oliguria and impaired renal function following streptococcal group A â hemolytic streptococcal throat and skin infection. There is a declining incidence of APSGN worldwide, particularly in industrialized nations because of easier and earlier access to competent medical treatment of streptococcal infections and the widespread use of fluorination of water since virulence factors in streptococcus pyogens are reduced with fluoride exposure. But in the underdeveloped world, global burden of APSGN continues to be significant with lower estimate of 9.3 to 9.8 cases per 1,00,000 population per year to higher estimates as high as three times these values. Furthermore, clusters of cases are more frequently reported in poor communities in industrialized countries while epidemics of more than 100 cases are reported in the middle ranger countries with mean annual health expenditure per capita of about 550 US dollars. APSGN typically follows 1to2 weeks after pharyngeal infection and 2 to 4 weeks after skin infection by nephritogenic strains of group A â hemolytic streptococcus in a range of 5 – 15 years of age. Subclinical cases are 4 – 10 times higher than symptomatic patients. The acute phase generally resolves within 4-8 weeks but microscopic hematuria may persist for 1-2 yr after the initial presentation. Acute complications of symptomatic patients are hypertensive heart failure, encephalopathy and retinopathy. There can be acute renal failure and rarely rapidly progressive ( crescentic) glomerulonephritis, hyperkalemia, hyperphosphatemia, hypocalcemia and acidosis. Treatment is directed towards reduction of hypertension, but prompt address of complications are essential to avoid immediate mortality. Heart failure is treated with diuretic and anti-hypertensive, digoxin is ineffective. Hypertensive encephalopathy is treated by I.V phenobarbitone for convulsion, supportive measures for unconsciousness and blood pressure control. Acute renal failure is managed by supportive measures, rarely requires dialysis. Short and long term prognosis is excellent, with1% mortality during acute stage and 1% ending up with chronic kidney disease, but in higher age group abnormal urinalysis are present in higher number of patients. DOI: http://dx.doi.org/10.3329/bjch.v38i1.20025 Bangladesh J Child Health 2014; VOL 38 (1) : 32-39

A One-Pot Diazotation–Fluorodediazoniation Reaction and Fluorine Gas for the Production of Fluoronaphthyridines

Several synthetic routes to 7-fluoro-2-methoxy-8-methyl-1,5-naphthyridine (1) are presented, and their suitability for scale-up is discussed. The way of introducing the fluorine atom is crucial. Early routes start from commercially available fluorinated building blocks or employ F+ reagents like SelectFluor and delivered up to 70 kg of 7-fluoro-2-methoxy-1,5-naphthyridine (18). To prepare for larger scales, the focus turned to the use of HF or elemental fluorine, both one of the cheapest sources of fluorine. The first method, a one-pot diazotation–fluorodediazoniation with 6-methoxy-1,5-naphthyridin-3-amine (9) in HF gave the fluorinated naphthyridine 18 in high yield and purity without isolation of the unstable diazonium salt, the latter being a severe drawback of the related Balz–Schiemann protocol. The second method relies on the use of fluorine gas for a surprisingly selective ortho-fluorination of 6-methoxy-1,5-naphthyridin-4-ol (10).

Advanced-stage Hodgkin Lymphoma: US/Chest Radiography for Detection of Relapse in Patients in First Complete Remission—A Randomized Trial of Routine Surveillance Imaging Procedures

To compare the use of fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) with the use of a combination of ultrasonography (US) and chest radiography for systematic follow-up of patients with high-risk Hodgkin lymphoma. Institutional review board approval and informed consent were obtained. In a single center between January 2001 and December 2009, patients with advanced-stage Hodgkin lymphoma who had responded completely to first-line treatment were randomly assigned (1:1) to follow-up with either PET/CT or US/chest radiography. Follow-up included clinical and imaging procedures at 4, 8, 12, 16, 20, 24, 30, 36, 48, 60, 84, and 108 months after treatment discontinuation. When clinical and/or imaging results were positive, recurrence was confirmed histologically. The primary endpoint was to compare the sensitivity of the two follow-up imaging approaches. Secondary endpoints were their specificity, positive and negative predictive values, time to recurrence detection, radiation risks, and costs. A total of 300 patients were randomized into the two arms. The study was closed after a median follow-up time of 60 months, with a relapse rate of 27%. Sensitivity for detection of Hodgkin lymphoma was similar for the two follow-up approaches. All of the relapses (40 of 40) were identified with FDG PET/CT (100%) and 39 of 40 relapses were identified with US/chest radiography (97.5%; P = .0001 for the equivalence test). US/chest radiography showed significantly higher specificity and positive predictive value than did PET/CT (96% [106 of 110] vs 86% [95 of 110], respectively; P = .02; and 91% [39 of 43] vs 73% [40 of 55], respectively; P = .01). Exposure to ionizing radiation was estimated to be 14.5 mSv for one PET/CT examination versus 0.1 mSv for one chest radiographic examination. Estimated cost per relapse diagnosed with routine PET/CT was 10-fold higher compared with that diagnosed with routine US/chest radiography. US and chest radiography are diagnostic tools that enable effective, safe, and low-cost routine surveillance imaging for patients at high risk of Hodgkin lymphoma relapse.