On the formulation and the calculation of the harmonic contributions to the Debye-Waller factor in metals (sodium)

The algebraic expressions for the anharmonic contributions to the Debye-Waller factor up to 0(A ) and 0 L% ) £ where ^ is the scattering wave-vector] have been derived in a form suitable for cubic metals with small ion cores where the interatomic potential extends to many neighbours. This has been achieved in terms of various wave-vector dependent tensors, following the work of Shukla and Taylor (1974) on the cubic anharmonic Helmholtz free energy. The contribution to the various wave-vector dependent tensors from the coulomb and the electron-ion terms in the interatomic metallic potential has been obtained by the Ewald procedure. All the restricted multiple whole B r i l l o u i n zone (B.Z.) sums are reduced to single whole B.Z. sums by using the plane wave representation of the delta function. These single whole B.Z. sums are further reduced to the •%?? portion of the B.Z. following Shukla and Wilk (1974) and Shukla and Taylor (1974). Numerical calculations have been performed for sodium where the Born-Mayer term in the interatomic potential has been neglected because i t is small £ Vosko (1964)3 • *n o^er to compare our calculated results with the experimental results of Dawton (1937), we have also calculated the r a t io of the intensities at different temperatures for the lowest five reflections (110), (200), (220), (310) and (400) . Our calculated quasi-harmonic results agree reasonably well with the experimental results at temperatures (T) of the order of the Debye temperature ( 0 ). For T » © ^ 9 our calculated anharmonic results are found to be in good agreement with the experimental results.The anomalous terms in the Debye-Waller factor are found not to be negligible for certain reflections even for T ^ ©^ . At temperature T yy Op 9 where the temperature is of the order of the melting temperature (Xm) » "the anomalous terms are found to be important almost for all the f i ve reflections.

Development of an electrochemical sensor based on nanostructured hausmannite-type manganese oxide for detection of sodium ions

The preparation and electrochemical characterization of hausmannite-type manganese oxide to use as a sensing material for sodium ion is described. This paper reports a new via synthetic to obtain of the hausmannite-type manganese oxide and its application in the construction of modified electrode as a voltammetric sensor. The electrochemical activity of hausmannite-type manganese oxide is controlled by intercalation/deintercalation of the sodium ions within the oxide lattice. The detection is based on the measurement of anodic current generated by oxidation of MnIII-MnIV at electrode surface. The best electrochemical response was obtained for a sensor composition of 20% (w/w) hausmannite oxide in the paste, a TRIS buffer solution of pH 6.0-7.0 and a scan rate of 50 mV s-1. A sensitive linear voltammetric response for sodium ions was obtained in the concentration range of 2.01 × 10 -5-2.09 × 10-4 mol L-1 with a slope of 355 μA L mmol-1 and a detection limit of 7.50 × 10 -6 mol L-1 using cyclic voltammetry. The use of hausmannite has significantly improved the selectivity of the sensor compared to the birnessite-type manganese oxide modified electrode. Under the working conditions, the proposed method was successfully applied to determination of sodium ions in urine samples. © 2013 Elsevier B.V.

Lack of DNA damage induced by fluoride on mouse lymphoma and human fibroblast cells by single cell gel (comet) assay

Fluoride has widely been used in Dentistry because it is a specific and effective caries prophylactic agent. However, excess fluoride may represent a hazard to human health, especially by causing injury on genetic apparatus. Genotoxicity tests constitute an important part of cancer research for risk assessment of potential carcinogens. In this study, the potential DNA damage associated with exposure to fluoride was assessed by the single cell gel (comet) assay in vitro. Mouse lymphoma and human fibroblast cells were exposed to sodium fluoride (NaF) at final concentration ranging from 7 to 100 μg/mL for 3 h at 37μC. The results pointed out that NaF in all tested concentrations did not contribute to DNA damage as depicted by the mean tail moment and tail intensity for both cellular types assessed. These findings are clinically important because they represent a valuable contribution for evaluation of the potential health risk associated with exposure to agents usually used in dental practice.

Base de dados de informação nutricional, relacionados com doenças crônicas não transmissíveis, de alimentos comercializados no Brasil

A recente evolução das doenças crônicas não transmissíveis (DCNT), possivelmente associadas às mudanças de hábitos alimentares, tem sido um desafio para a promoção da alimentação saudável em vários países, inclusive no Brasil, onde o sódio tem sido o foco de atenção, pela possibilidade da redução da sua elevada ingestão ser uma das medidas com melhor custo benefício para saúde pública. É necessário conhecer o conteúdo de sódio e de componentes específicos, relacionados às DCNT nos alimentos comercializados no país, para orientar o consumidor na seleção adequada dos alimentos e mesmo para modificar sua composição; no entanto, nas bases de dados, o conteúdo desse mineral está presente em um número reduzido de alimentos. O objetivo da presente pesquisa foi a elaboração de uma base de dados de alimentos processados com componentes específicos associados às DCNT, dando ênfase ao sódio, e avaliar o uso dessa base de dados para estimar a sua ingestão. Informações nutricionais de rótulos e de websites de indústrias de alimentos foram coletadas para inclusão na base de dados, elaborada de acordo com as diretrizes do International collaborative project to compare and monitor the nutritional composition of processed foods, coordenado pelo The George Institute for Global Health (Austrália). A avaliação da variação do conteúdo de sódio foi realizada para alguns alimentos processados presentes na base de dados, considerando os de maior consumo nacional. O conteúdo de sódio em refeições de restaurantes populares de São Paulo foi analisado por espectrofotometria de absorção atômica de chama e estimado pela base de dados elaborada para comparação. Na base de dados estão incluídas informações de 2.319 alimentos distribuídos em 14 grupos. Foi observada grande variação no conteúdo de sódio entre diferentes tipos de pães de forma industrializados, de salsichas, de linguiças, de queijos e iogurtes. O conteúdo de sódio analisado nas refeições (base integral) variou de 215,9 mg a 427,9 mg por 100 kcal, enquanto que o conteúdo de sódio estimado variou de 204,2 mg a 486,8 mg por 100 kcal (418 kJ). A análise do coeficiente de correlação entre valores analíticos e estimados do conteúdo de sódio em refeições mostrou forte correlação entre esses dados para dois restaurantes (r=0,703 e 0,897) e moderada correlação para outros dois (r=0,513 e 0,622) dos cinco restaurantes estudados, indicando que através da base de dados elaborada é possível obter uma estimativa da ingestão de sódio. A importância de se conhecer o conteúdo de sódio de refeições e/ou alimentos está na possibilidade de uso dessas informações para orientar a redução do sal empregado no preparo da refeição, e ampliar para o consumidor informações que permitam identificar alternativas para redução do consumo de sal.

Salt intakes, knowledge, and behavior in Samoa: monitoring salt-consumption patterns through the World Health Organization's Surveillance of Noncommunicable Disease Risk Factors (STEPS)

This project measured population salt intake in Samoa by integrating urinary sodium analysis into the World Health Organization's (WHO's) STEPwise approach to surveillance of noncommunicable disease risk factors (STEPS). A subsample of the Samoan Ministry of Health's 2013 STEPS Survey collected 24-hour and spot urine samples and completed questions on salt-related behaviors. Complete urine samples were available for 293 participants. Overall, weighted mean population 24-hour urine excretion of salt was 7.09 g (standard error 0.19) to 7.63 g (standard error 0.27) for men and 6.39 g (standard error 0.14) for women (P=.0014). Salt intake increased with body mass index (P=.0004), and people who added salt at the table had 1.5 g higher salt intakes than those who did not add salt (P=.0422). A total of 70% of the population had urinary excretion values above the 5 g/d cutoff recommended by the WHO. A reduction of 30% (2 g) would reduce average population salt intake to 5 g/d, in line with WHO recommendations. While challenging, integration of salt monitoring into STEPS provides clear logistical and cost benefits and the lessons communicated here can help inform future programs.

Sodium hydroxide enhances extractability and analysis of proanthocyanidins in ensiled sainfoin (onobrychis viciifolia)

Little information exists on the effects of ensiling on condensed tannins or proanthocyanidins. The acetone–butanol–HCl assay is suitable for measuring proanthocyanidin contents in a wide range of samples, silages included, but provides limited information on proanthocyanidin composition, which is of interest for deciphering the relationships between tannins and their bioactivities in terms of animal nutrition or health. Degradation with benzyl mercaptan (thiolysis) provides information on proanthocyanidin composition, but proanthocyanidins in several sainfoin silages have proved resistant to thiolysis. We now report that a pretreatment step with sodium hydroxide prior to thiolysis was needed to enable their analysis. This alkaline treatment increased their extractability from ensiled sainfoin and facilitated especially the release of larger proanthocyanidins. Ensiling reduced assayable proanthocyanidins by 29%, but the composition of the remaining proanthocyanidins in silage resembled that of the fresh plants.

Determination of sodium oxalate in Bayer liquor using flow-analysis incorporating an anion exchange column and tris(2,2`-bipyridyl)ruthenium(II) chemiluminescence detection

Semi-automated flow injection instrumentation, incorporating a small anion exchange column coupled with tris(2,2′-bipyridyl)ruthenium(II) (Ru(bipy)₃²⁺) chemiluminescence detection, was configured and utilised to develop rapid methodology for the determination of sodium oxalate in Bayer liquors. The elimination of both negative and positive interferences from aluminium(III) and, as yet, unknown concomitant organic species, respectively are discussed. The robustness of the methodology was considerably enhanced by using the temporally stable form of the chemiluminescence reagent, tris(2,2′-bipyridyl)ruthenium(III) perchlorate in dry acetonitrile. Real Bayer process samples were analysed and the results obtained compared well with those performed using standard methods within industrial laboratories.

Determination of sodium oxalate in Bayer process liquors using flow analysis with tris(2,2'-bipyridyl)ruthenium(II) chemiluminescence detection

The research was a detailed investigation into a challenging analytical chemistry problem for the alumina industry. The successful outcomes were derived through innovative reagent chemistry and novel instrumental development. The resultant methodology and instrumentation deployed on this most demanding sample matrix is more robust, reliable and less expensive than anything currently used in this industry worldwide.

Surface modification and properties analysis of shell powder with sodium stearate surface modifier

In this study, shell powder was modified by sodium stearate surface modifier for improving the compatibility of SP with polymer materials. The surface modifiers influence on the physical and chemical properties of SP were studied by scanning electron microscope(SEM), fourier infrared spectrum(FT-IR), surface contact angle meter, XRD diffraction analysis meter and other modern instruments and analysis method. The results showed that the surface modifier was successfully coupled to the shell powder surface. After surface modifier modification, the interfacial compatibility of the shell powder with polymer materials was effectively improved. The contact angle of shell powder surface increased from 73.5 ° to 110.8 °, along with the dosage of sodium stearate surface modifier was 4.0%. All results suggested that modified shell powder is promising for using as a reinforcement filler in polymer materials. © (2014) Trans Tech Publications, Switzerland.

Influence of enamel matrix derivative (Emdogain((R))) and sodium fluoride on the healing process in delayed tooth replantation: histologic and histometric analysis in rats

Although it has already been shown that enamel matrix derivative (Emdogain((R))) promotes periodontal regeneration in the treatment of intrabony periodontal defects, there is little information concerning its regenerative capacity in cases of delayed tooth replantation. To evaluate the alterations in the periodontal healing of replanted teeth after use of Emdogain((R)), the central incisors of 24 Wistar rats (Rattus norvegicus albinus) were extracted and left on the bench for 6 h. Thereafter, the dental papilla and the enamel organ of each tooth were sectioned for pulp removal by a retrograde way and the canal was irrigated with 1% sodium hypochlorite. The teeth were assigned to two groups:in group I, root surface was treated with 1% sodium hypochlorite for 10 min (changing the solution every 5 min), rinsed with saline for 10 min and immersed in 2% acidulated-phosphate sodium fluoride for 10 min; in group II, root surfaces were treated in the same way as described above, except for the application of Emdogain((R)) instead of sodium fluoride. The teeth were filled with calcium hydroxide (in group II right before Emdogain((R)) was applied) and replanted. All animals received antibiotic therapy. The rats were killed by anesthetic overdose 10 and 60 days after replantation. The pieces containing the replanted teeth were removed, fixated, decalcified and paraffin-embedded. Semi-serial 6-mu m-thick sections were obtained and stained with hematoxylin and eosin for histologic and histometric analyses. The use of 2% acidulated-phosphate sodium fluoride provided more areas of replacement resorption. The use of Emdogain((R)) resulted in more areas of ankylosis and was therefore not able to avoid dentoalveolar ankylosis. It may be concluded that neither 2% acidulated-phosphate sodium fluoride nor Emdogain((R)) were able to prevent root resorption in delayed tooth replantation in rats.

Microscopical analysis of Candida albicans biofilms on heat-polymerised acrylic resin after chlorhexidine gluconate and sodium hypochlorite treatments

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Delayed tooth replantation after root surface treatment with sodium hypochlorite and sodium fluoride: Histomorphometric analysis in rats

In cases of delayed tooth replantation, non-vital periodontal ligament remnants have been removed with sodium hypochlorite in an attempt to control root resorption. Nevertheless, reports of its irritating potential in contact with the alveolar connective tissue have been described. Therefore, this study evaluated the healing process on delayed replantation of rat teeth, after periodontal ligament removal by different treatment modalities. Twenty-four rats, assigned to 3 groups (n=8), had their upper right incisor extracted and left on the workbench for desiccation during 60 min. Afterwards, the teeth in group I were immersed in saline for 2 min. In group II, root surfaces were scrubbed with gauze soaked in saline for 2 min; and in group III, scrubbing was done with gauze soaked in 1% sodium hypochlorite solution. Thereafter, root surfaces were etched with 37% phosphoric acid and immersed in 2% acidulate-phosphate sodium fluoride solution, at pH 5.5. Root canals were filled with a calcium hydroxide-based paste and the teeth were replanted. The animals were sacrificed 60 days postoperatively and the pieces containing the replanted teeth were processed and paraffin- embedded. Semi-serial transversally sections were obtained from the middle third of the root and stained with hematoxylin and eosin for histomorphometric analysis. Data were analyzed statistically using Kruskal-Wallis and Dunn's tests. The results showed that root structure and cementum extension were more affected by resorption in group III (p<0.05). All groups were affected by root resorption but the treatment performed in group III was the least effective for its control. The treatment accomplished in groups I and II yielded similar results to each other.

Evaluation of the Interaction Between Sodium Hypochlorite and Several Formulations Containing Chlorhexidine and its Effect on the Radicular Dentin-SEM and Push-Out Bond Strength Analysis

The aim of the current study was to evaluate the presence of debris and smear layer after endodontic irrigation with different formulations of 2% chlorhexidine gluconate (CHX) and its effects on the push-out bond strength of an epoxy-based sealer on the radicular dentin. One hundred extracted human canines were prepared to F5 instrument and irrigated with 2.5% sodium hypochlorite and 17% ethylenediaminetetraacetic acid. Fifty teeth were divided into five groups (n=10), according to the final irrigation protocol with different 2% CHX formulations: G1 (control, no final rinse irrigation), G2 (CHX solution), G3 (CHX gel), G4 (Concepsis), and G5 (CHX Plus). In sequence, the specimens were submitted to scanning electron microscopy (SEM) analysis, in the cervical-medium and medium-apical segments, to evaluate the presence of debris and smear layer. The other 50 teeth were treated equally to a SEM study, but with the root canals filled with an epoxy-based endodontic sealer and submitted to a push-out bond strength test, in the cervical, middle, and apical thirds. G2, G3, G4, and G5 provided higher precipitation of the debris and smear layer than G1 (P<0.05), but these groups were similar to each other (P>0.05), in both segments. The values obtained in the push out test did not differ between groups, independent of the radicular third (P>0.05). The CHXs formulations caused precipitation of the debris and smear layer on the radicular dentin, but these residues did not interfere in the push-out bond strength of the epoxy-based sealer. Microsc. Res. Tech. 77:17-22, 2014. (c) 2013 Wiley Periodicals, Inc.