Fluor Concentration Research Articles

A feasibility study on distinguishing fluor concentrations in liquid scintillators from scintillation events observed by photomultiplier tubes using convolutional neural networks

A feasibility study on distinguishing fluor concentrations in liquid scintillators from scintillation events observed by photomultiplier tubes using convolutional neural networks

Feasibility Study on the Discrimination of Fluor Concentration in the Liquid Scintillator Using PMT Waveform and Short-Pass Filter

Neutrinos are difficult to detect because they weakly interact with matter, making their properties least known. The response of the neutrino detector depends on the optical properties of the liquid scintillator (LS). Monitoring any characteristic changes in the LS helps to understand the temporal variation of detector response. In this study, a detector filled with LS was used to study the characteristics of the neutrinos detector. We investigated a method to distinguish the concentrations of PPO and bis-MSB, which are fluors added to LS, through a photomultiplier tube (PMT) acting as an optical sensor. Conventionally, it is very challenging to discriminate the flour concentration dissolved in LS. We employed the information of pulse shape and PMT coupled with the short-pass filter. To date, no literature report on a measurement using such an experimental setup has been published. As the concentration of PPO was increased, changes in the pulse shape were observed. In addition, as the concentration of bis-MSB was increased, a decrease in the light yield was observed in the PMT equipped with the short-pass filter. This result suggests the feasibility of real-time monitoring of LS properties, which are correlated with the fluor concentration, using a PMT without extracting the LS samples from the detector during the data acquisition process.

COMPARISON FLUORIDE CONCENTRATION IN SALIVA BETWEEN FLUORIDE VARNISH AND GLASS IONOMER CEMENT

Background: Caries is one of the most common dental diseases. Caries prevention by improving dental health has become a major goal in the world of dentistry.Topical application of fluoride is one of the most effective ways to prevent caries.Glass ionomer cement and fluoride varnish has the effect of preventing dental caries because these materials release fluoride. There is no better treatment for demineralization than prevention itself. One of these steps is the combination of dental restorative materials with the application of topical fluoride as an additional source of fluoride.Method: A total of 32 permanent premolar teeth samples, immersed in artificial saliva before and after the application of fluoride varnish and glass ionomer cement. The measurement of fluoride levels in saliva was carried out using a spectrophotometric tool.Result: Independent T-test results obtained sig. below 0.05 indicates that there are differences in the level of fluoride levels between the fluoride varnish group and the glass ionomer cement.Conclusion: Fluoride varnish and glass ionomer cement can increase fluor concentration in salivaÂ

Concentración de flúor y arsénico en el agua de red de General Pico (Argentina) durante el periodo 2007-2013

Concentración de flúor y arsénico en el agua de red de General Pico (Argentina) durante el periodo 2007-2013

Surface Structure Study of Crystal Hydroxy-Apatite from Fluorosis Enamels

Fluorosis is a condition due to ingestion of excessive amounts of fluor which can cause the change in tooth structure and strength. However, there is still lack of explanation on the surface structure of crystal hydroxyapatite that influences the microscopic characteristic of fluorosis enamel. Objectives: To investigate the surface structure of crystal hydroxy-apatite in fluorosis enamel. Materials and Methods: Determination of fluor concentration and the surface structure of normal and fluorosis enamel specimen were carried out by using Scanning Electron Microscopy/Energy Disperse X-Ray (SEM/EDX). Results: Fluor concentration of fluorosis enamel was significantly higher with increased surface roughness and porosity than normal enamel. SEM observation also showed gaps areas between enamel rods and visible aprismatic zone in some regions. Conclusion: High level of fluor concentration on fluorosis enamel indicated the subtitution of OH- by F- increasing the surface roughness of enamel surface. DOI: 10.14693/jdi.v16i3.100

Development of polystyrene-based scintillation materials and its mechanisms

Scintillation materials based on polystyrene (PS) have been investigated. Para-terphenyl was employed as a fluorescent molecule (fluor) that functions as a wavelength shifter. A clear increase in photon yield of the scintillation materials relative to the pure PS was observed, which cannot be explained by the conventional theory of scintillation mechanism. Furthermore, the photon yield increased with flour concentration in accordance with a power-law. Here we reveal the emergence of a luminescence of PS-based scintillation materials and demonstrate that their photon yields can be controlled by the fluor concentration.

Relationship between salivary fluor concentration and caries index in 12–15 years old children

Background: Dental caries is a bacterial infection leading to dissolution and localized damage of hard tissues. The assessment of caries risk is based on several caries indicators including clinical conditions (DMF-T index), environment (fluor), and general health. Purpose: The objective of this study was to assess the relationship between salivary fluor concentration and caries index in children aging 12–15 years old at SMP Negeri 2 PTPN VIII Pangalengan. Methods: This study is an observational analytical study using crosssectional approach and is conducted in a field trial manner. The study sample consists of 80 students in the age of 12 to 15 years old at SMP Negeri 2 PTPN VIII selected through Probability Sampling manner using simple random sampling method. Results: The result of this study shows a DMF-T index of 4.32 and salivary fluor concentration mean of 0.018. Pearson Product Moment correlation test shows that there is a weak correlation between salivary fluor concentration and DMF-T index. Conclusion: It is concluded that the salivary fluor concentration has an insignificant correlation with the DMF-T index since the fluor concentration in saliva is very low.Latar belakang: Karies gigi adalah penyakit infeksi bakteri yang berakibat pada disolusi dan kerusakan terlokalisasi jaringan keras. Penilaian risiko karies berdasarkan atas beberapa indikator karies yaitu kondisi klinis (indeks DMF-T), lingkungan (fluor), dan kesehatan umum. Tujuan: Penelitian ini bertujuan untuk mengetahui hubungan konsentrasi fluor yang terdapat dalam saliva dengan indeks karies pada anak usia 12-15 tahun di SMP Negeri 2 PTPN VIII Pangalengan. Metode: Jenis penelitian ini adalah penelitian analitik observasional dengan pendekatan cross sectional yang dilakukan di lapangan. Sampel penelitian sebanyak 80 orang siswasiswi usia 12–15 tahun di SMP Negeri 2 PTPN VIII Pangalengan yang dipilih secara Probability Sampling dengan metode simple random sampling. Hasil: Hasil penelitian menunjukkan indeks DMF-T 4,32 dan rerata konsentrasi fluor dalam saliva sebesar 0,018. Tes korelasi Pearson Product Moment menunjukkan hubungan yang tidak kuat antara konsentrasi fluor dalam saliva dengan indeks DMF-T. Kesimpulan: Dapat disimpulkan konsentrasi fluor dalam saliva mempunyai hubungan dengan indeks DMF-T tetapi tidak signifikan dikarenakan nilai konsentrasi fluor dalam saliva yang sangat rendah.

Relationship between Fluor Concentration and Structure Pattern of Enamel Prism in Enamel Surface after Coffee and Black Tea Exposure

ABSTRACT Coffee and tea are often consumed by Indonesian and Aceh people. Based on previous research reported that concentration of fluor in coffee and tea affects pattern structure of enamel prism. Currently, little explanation about relationship between fluor concentrations and pattern structure of enamel prism in enamel surface after coffee and tea drinking water exposure. The purpose of this study is to explain relationship between fluor concentrations and pattern structure of enamel prism in enamel surface after coffee and tea drinking water exposure. Materials and methods Eight maxillary premolars were divided into control and treatment group. Positive control group exposure to NaCl 0.9%, negative control group exposure to sulfuric acid 50%, treatment groups are exposure to coffee and tea drinking water. This study conducted by scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX). Data analysis is descriptive qualitative. Results Fluor in tea increases the density of the enamel prism structure pattern. Surface enamel that exposed to tea has described better arrangement of enamel prism pattern than enamel surface that exposed to coffee. Conclusion Fluor concentration in drinking water has relationship with structure patterns of enamel prism. The structure patterns of enamel prism that exposed to tea have better arrangement than enamel that exposed to coffee. How to cite this article Nasution AI, Gani BA, Pospos RM. Relationship between Fluor Concentration and Structure Pattern of Enamel Prism in Enamel Surface after Coffee and Black Tea Exposure. World J Dent 2012;3(4):284-289.

Nanostructure of Crystal Hydroxyapatite from Fluorosis: Affected Enamel

ABSTRACT Fluorosis is a condition due to ingestion of excessive amounts of fluor which can cause the change the teeth structure and strength. Currently, a little explanation was available to describe the surface and change of nanostructure crystal hydroxyapatite which contribute to influence the macrocharacteristic of fluorosis enamel. Aims and objectives To describe the change of surface structure, c-axis, a-axis and grain size of crystal hydroxyapatite on fluorosis enamel. Materials and methods This research was carried out the fluorosis and normal enamel specimen by using scanning electron microscopy/ energy disperse X-ray (SEM/EDX) to determine fluor concentration and the surfaces structure of fluorosis enamel, and powder X-ray diffraction (XRD) to determine change of c- and a-axis of hydroxyapatite of fluorosis enamel. Results Fluor concentration were higher in fluorosis enamel and the surface increasingly roughness and porous. SEM/EDX also confirmed gaps areas between enamel rods and visible aprismatic zone in some regions. The axis on fluorosis enamel was a-axis = 9.3786 Å and c-axis = 6.8836 Å. The a-axis on normal enamel was = 9.4148 Å and c-axis = 6.8791 Å. Grain size of fluorosis enamel was 19.59 nm and normal enamel was 20.30 nm. Conclusion Fluor as most electronegative element changes the c-axis, a-axis, and grain size of crystal hydroxyapatite and generates the internal atomic bonding which influences the stability of enamel strength.

Nd loaded liquid scintillator to search for 150Nd neutrinoless double beta decay

The 150Nd is considered one of the most attractive candidate for searching neutrinoless double beta (0νββ-) decay, thanks to its high Q-value (3.367 MeV), that makes the external background issue less significative respect to other isotopes, and favorable computed matrix elements. The isotopic abundance of this isotope in natural neodimium is only 5.6% and up to now, it has been investigated only in low mass experiments. The next step is to increase the sensitivity of the experiments using larger mass of neodymium (10 ton-1 kton). This could be possible with a Nd loaded liquid scintillator (LS). At the Gran Sasso National Laboratory (LNGS), a joint INFN (Istituto Nazionale di Fisica Nucleare) and INR (Institute for Nuclear Research of Moscow) working group has been carrying out since 2001 an R&D activity aiming to develop organic liquid scintillators (LS) doped with metals. The achieved know-how and the satisfactory results obtained both with In and Gd allowed to face the development and production of Nd doped LS. The development of metal doped LS is challenging because the metal has to be embedded in a proper organic system that makes it soluble in an organic solvent minimizing the impact of the metal-organic compound on the optical and scintillation properties of the LS. A further challenge in the case of Nd is the presence of absorption bands of this element in the optical region with a transparent region around 400 nm, which is about at the maximum of the scintillator emission spectrum. A 2.5 1 Nd loaded LS has been produced diluting an originally developed Nd-Carboxylic (Nd-CBX) salt in pseudocumene (PC), the solvent of the Borexino liquid scintillator. The measured light yield, at [Nd] = 6.5 g/1 and [PPO] = 1.5 g/1, is ∼ 75% of pure PC at the same fluor concentration (~ 10000 ph/MeV). The Nd doped LS has been tested in a 2 1 quartz cell (wrapped by VM2000 reflector film) having dimensions 5x5x100 cm3. The light propagates in the cell by total internal reflection at the external quartz/air interface and is reflected by the VM2000 foil. The light is trasmitted at the windows of the cell where 3-inch PMTs (one for each end) are coupled. Two fillings have been performed: distilled PC (PPO-1.5 g/1) and Nd loaded LS (Nd-6.5 g/1, PPO-1.5 g/1, MSB-30 mg/1). In both cases, the cell is irradiated with a 137Cs source, scanning different positions along the cell axis. For each position the Compton Edge (CE) in the spectrum has been fitted. The optical attenuation length measured with this methodic is: 210±10 cm (only stat error, systematics not yet investigated). The measurements performed by ICP-MS of the radiopurity of the Nd2O3, that is the compound from which the Nd-CBX salt is synthesized, and of the content of optically active impurities show that a purification procedure is needed. Further investigations, at the ppt level, on the Th content in Nd2O3 is planned with the Borexino CTF.

Penanganan fluorosis pada gigi sulung dengan menggunakan teknik mikroabrasi

Fluorosis is a pathological endemic effect of ion intake of flour which is more than 1ppm. Enamel fluorosis is tooth enamel demineralization due to excessive flour intakeduring tooth calcification period. Fluorosis is disparity of tooth which is initially markedwith a white line across the enamel surface, and at severe level can change tooth form.Dental fluorosis is hypoplasia or hypomaturation of tooth enamel or dentine because ofchronic usage of excessive fluor at period and development of dentition. Dental fluorosisis qualitative defect of enamel, resulted from the increase of fluor concentration at cellmicroenvironment of ameloblast during development and tooth formation. Quantitativedefect of enamel can occur on severe type of dental fluorosis. Microabrasion, consist ofair abrasion and enamel microabrasion, is a method of reducing tooth structure which isthe best alternative rather than drilling method. The mechanism of air abrasion techniqueis blast pressure of abrasive particles to remove tooth caries. The principle of kineticenergy is the abrasive particles with high pressure and speed, hit the tooth, remove toothcaries, and reduce tooth structure.

Faktor - Faktor yang Berhubungan dengan Derajat Kaparahan Karies di Kecamatan Slawi Kabupaten Tegal Propinsi Jawa Tengah Tahun 1998

Residence of Slawi Subdistrict, Tegal District Central Java Province have a frequent tea drinking habit with specific characters of high concentrate tea without sugar or a lot of sugar. It is acknowledged that fluor content in tea can prevent dental caries, while sugar, a sucrose type of carbohydrate in the tea is most cariogenic. The subject of the study, regarding the tea drinking habit, is to obtain information about factors correlated to severity of dental caries in residence of the Slawi Subdistrict, Tegal Distric, Central Java Province. The study type is cross sectional with a sample size of 140. The subjects of the study were residents of Slawi Subdistric with age ranging from 18 to 44 years. An interview was conducted to obtain information of tea drinking characteristics. Samples of tea, water and sugar from each subject examined in a laboratory to obtain the information about fluor and and sugar contents in tea. Saliva examination was also conducted to know its buffer capacity and flow rate. Intra oral clinical examination was conducted to obtain DMF-T and plaque scores. Statistical analysis was applied with multiple linear regression methods using SPSS 7.5 and Stata version 4. The result of the study show that caries prevalence of 76.92% in subjects with tea drinking habit without sugar. The subjects had a 2.85 DMF-T score. Meanwhile caries prevalence was 98.15% for subjects with tea drinking habit with sugar. The subjects had a 6.15 DMF-T score. The mean of fluor concentration in all subjects drinking water was 0.11 mg/l, and 5.26% for sugar content. 68.94% of DMF-T score variation concluded in the multiple linear regression model, is showed by the factors in the model.

Characterization of fluor concentration and geometry in organic scintillators for in situ beta imaging

Development of a small area (1-2 cm/sup 2/) in situ beta imaging device includes optimization of the front end scintillation detector, which is fiber optically coupled to a remote photon detector. Thin plastic scintillation detectors, which are sensitive to charged particles, are the ideal detectors due to the low sensitivity to ambient gamma backgrounds. The light output of a new binary plastic scintillator was investigated with respect to increasing concentrations of the fluor (0.5-2.0% by weight) and varying thickness cylindrical configurations of the intended imaging detector. The fluor had an emission maximum increasing from 431 to 436 nm with increasing fluor concentration. The decay time(s) had two components (0.38 and 1.74 ns). There was an /spl sim/20% increase in light output with increasing fluor concentration, measured with both /sup 204/Tl betas and conversion electrons from /sup 207/Bi. The highest light output of this new scintillator was measured to be /spl sim/30% lower than BC404. Simulations predicted the 1.5 mm scintillator thickness at which light output and energy absorption for /spl sim/700 keV electrons (e.g., from /sup 204/Tl, /sup 18/F) were maximized, which corresponded with measurements. As beta continua are relatively featureless, energy calibration for the thin scintillators was investigated using Landau distributions, which appear as distinct peaks in the spectra. As the scintillators were made thinner, gamma backgrounds were shown to linearly decrease.

Readout of undoped CsI and CeF/sub 3/ crystals using scintillating fibers and bars

An investigation has been made of a readout technique for undoped cesium iodide and cerium fluoride crystals using scintillating fibers and bars. The method uses the fluors in the scintillator as wavelength shifters to absorb the primary UV scintillation light from the crystals and reemit it at a longer wavelength which can be more easily propagated over large distances. A study was made for various types of fibers (BCF-10, BCF-12 and BCF-20), giving the dependence of the light output on fluor type, fiber diameter and the spacing between fibers. Similar studies are made for several types of bars (BC-404 and BC-408) which compare the light output for various bar thicknesses, fluor concentrations and geometrical configurations. An initial investigation also showed that this technique can be used to read out CeF/sub 3/ crystals. >

A Feasability Study of Scintillator Microdosemeters for Measurement of the Biological Effectiveness of Ionising Radiations

Double-strand breaks in the intranuclear DNA are generally considered to be the precursors leading to the deleterious effects of ionising radiations in mammalian cells. If instrumentation can be designed with a detection response which simulates that of the DNA in cells then there is the possibility of developing a unified system of dosimetry which will be independent of radiation type. Interactions in site sizes of nanometre dimensions are involved. Active centres in the crystalline lattice of a scintillator, or the fluor solute in a plastic phosphor, have interaction cross sections for light emission which are typically a few nanometres squared. By adjusting the concentration of the activator, the mean of the random distance between centres can be modified to simulate the strand-pair distributions of the DNA in mammalian cells. To simulate the yield of initial damage (double-strand breaks), one must identify the number of pairs of sites activated which are separated by the requisite spacing of (2 nm and to distinguish these from unwanted pairs of sites that may be activated at different separation distances. Starting from a knowledge of the equilibrium slowing down electron spectrum in the material, a simplified approach is used to determine the yields of scintillation photons and paired events and their relationship to biological effectiveness. As may be expected, the results show that the combination from the paired events is very small compared to the normal scintillation yield but is of the same order as the ratio of double to single strand breaks for electron irradiation of mammalian cells cells. Both the theory and preliminary experimental investigation with a semi-infinite disc of plastic phosphor, 20 µm thick, reveals that the method is potentially promising but that more detailed study is required for optimisation of the fluor concentration and on the process for extraction of the desired signal from the practical device. Validation of the instrumental response function could be made by direct comparison with effect cross section data available for various damage end-points in mammalian cells.

A Radiocarbon Dating Protocol for use with Packard Scintillation Counters Employing Burst-Counting Circuitry

Considerable research has been carried out in this laboratory on the use of Packard scintillation counters employing burst-counting circuitry. The nature of the pulse-shape discrimination circuit has led to redefining our sample vialing philosophy and scintillation cocktail optimization. Results presented here demonstrate: 1) the enhancements in efficiency that are achievable using a two-component cocktail compared with the use of a primary fluor only; 2) the development of a cocktail in which efficiency and quenching are relatively unaffected by moderate variations in fluor concentrations and ratio; 3) the rationale behind the use of screw-cap vials rather than sealable ampules; 4) the advantage of nickel/chromium-plated brass caps over standard plastic caps.

High dose calorimetry with scintillating fibers

The authors discuss two ways of insuring plastic scintillators against radiation damage: shifting to longer secondary fluor emission wavelengths and increasing secondary fluor concentration. They describe a scintillating-fiber-based calorimeter which can be made compensating. The calorimeter recovers its original resolution less than one month after receiving a dose of 10 Mrad via 100-MeV electrons. >

Chemiluminescence from reactions of bis(pentachlorophenyl)oxalate, hydrogen peroxide and fluorescent compounds. Kinetics and mechanism

The chemiluminescence arising from the reaction between bis(pentachlorophenyl)oxalate (PCPO) and hydrogen peroxide in the presence of the fluor 9,10-diphenylanthracene (DPA) has been examined in detail. The effects of varying reactant, base catalyst and fluor concentrations on chemiluminescence decay rates and quantum yields have been investigated and a mechanism which accounts for the kinetics of the reaction has been proposed. The rate-determining step is a reaction between PCPO and the hydroperoxide anion (OOH–) and does not involve the fluorescent activator. The lifetime of the reactive intermediate formed in the rate-determining step is short (5 × 10–7 s) and consistent with the proposed mechanism.

Wavelength-shifted Cherenkov radiators

The scintillation and Cherenkov responses of plastic Cherenkov radiators containing different wavelength-shifting fluors in varying concentrations have been studied in beams of low energy protons and pions. For cosmic ray applications, where large Cherenkov to scintillation ratios are desired, the optimum fluor concentrations are 2.5 × 10 −5 by weight or less.