The complex multi-sectoral impacts of drought: Evidence from a mountainous basin in the Central Spanish Pyrenees.

We analyzed the impacts of drought severity on a variety of sectors in a topographically complex basin (the upper Aragón basin 2181 km2) in the Central Spanish Pyrenees. Using diverse data sources including meteorological and hydrological observations, remote sensing and tree rings, we analyze the possible hydrological implications of drought occurrence and severity on water availability in various sectors, including downstream impacts on irrigation water supply for crop production. Results suggest varying responses in forest activity, secondary growth, plant phenology, and crop yield to drought impacts. Specifically, meteorological droughts have distinct impacts downstream, mainly due to water partitioning between streamflow and irrigation channels that transport water to crop producing areas. This implies that drought severity can extend beyond the physical boundaries of the basin, with impacts on crop productivity. This complex response to drought impacts makes it difficult to develop objective basin-scale operational definitions for monitoring drought severity. Moreover, given the high spatial variability in responses to drought across sectors, it is difficult to establish reliable drought thresholds from indices that are relevant across all socio-economic sectors. The anthropogenic impacts (e.g. water regulation projects, ecosystem services, land cover and land use changes) pose further challenges to assessing the response of different systems to drought severity. This study stresses the need to consider the seasonality of drought impacts and appropriate drought time scales to adequately assess and understand their complexity.

Three-dimensional numerical simulation of dental implants as orthodontic anchorage.

Endosseous oral implants have been used as orthodontic anchorage in subjects with multiple tooth agenesis, and their application under orthodontic loading has been demonstrated clinically and experimentally. The aim of this investigation was to examine three-dimensional (3D) bone and implant finite element (FE) models. The first model assumed that there was no osseointegration and the second that full osseointegration had occurred. These models were used to determine the pattern and distribution of stresses within the ITI-Bonefit endosseous implant and its supporting tissues when used as an orthodontic anchorage unit. The study examined a threaded implant placed in an edentulous segment of a human mandible with cortical and cancellous bone. The results, using both models, indicated that the maximum stresses were always located around the neck of the implant, in the marginal bone. Thus, this area should be preserved clinically in order to maintain the bone-implant interface structurally and functionally.

Efecto de la suplementación oral con sobre en el perfíl lipídico de pacientes venezolanos hiperlipémicos / Effect of copper suplementation in lipid profile of Venezuelan hiperlipemic patients

Se considera que la mayoría de las dietas occidentales satisfacen los requerimientos diarios de cobre debido a su presencia ubicua en los alimentos. Estudios recientes han demostrado que el cobre alimentario se encuentra a menudo por debajo de sus requerimientos diarios, lo que puede determinar una carencia de este elemento. Esta carencia está asociada con hipercolesterolemia e hipertrigliceridemia, tanto en humanos como en animales experimentales. En el presente estudio de intervención se examonó el efecto de la administración de 5mg de Cu/día, en 73 pacientes (grupo tratado), de ambos géneros, con edades entre 26y 48 años, con niveles séricos elevados de colesterol total y triglicéridos sin tratamiento con drogas hipolipémicas y se comparó con 73 pacientes hiperlipémicos no sometidos a tratamiento con Cu (grupo control), quienes fueron agrupados por género, edad, peso corporal, consumo de cigarrillos, ingesta de calorías y grasas y actividad física. Antes de administrar el cobre, se extrajo una muestra de sangre para las determinaciones de cobre, cinc y lípidos séricos. Al final del período experimental (45 días), se obtuvo una muestra de sangre para las determinaciones correspondientes. Los resultados sufieren la existencia de una cerencia marginal del elemento traza en el 38 por ciento de los sujetos y demuestran que el cobre disminuye significativamente (p<0.05) los nivles séricos del colesterol total (r=-0.976), de triglicéricos (r=-0.972), de LDL-colesterol (r=-0.961) y de cinc (r=-0.980) con un ligero incremento (r=-0.984) del HDL- colesterol. Estos hallazgos demuestran que el cobre se puede emplear en el tratamiento de los pacientes con hipercolesterolemia e hipertrigliceridemia; aunque los mecanismos, que explican como el cobre determina estos cambios, no se conocen exactamente

Niveles séricos de cinc y de vitamina A en pacientes con cáncer / Levels serum of zinc and of vitamin A in patients with cáncer

Los estudios epidemiológicos, clínicos y experimentales asocian los bajos niveles dietéticos y/o séricos de diversos antioxidantes y vitaminas con la incidencia elevada de ciertos tipos de cáncer. El presente estudio investiga el efecto del cáncer sobre la concentración sérica del cinz (Zn) y de la vitamina A (VA). Por esta razón, los niveles de Zn y de VA se determinaron en las muestras de suero de 90 pacientes con diferentes tipos de cáncer (42 de semana, 16 de tracto gastrointestinal, 16 genitourinarios, 8 de piel y 8 en otros sitios) y se compararon con los de 110 personas sanas agrupadas por género e índice de masa corporal (IMC). Las concentraciones de Zn y de VA fueron menores (p<0.05) en los cancerosos. El género, el estado nutricional y el tratamiento no influyen en los niveles séricos de estos micronutrientes. El Zn disminuye significativamente (p<0.05) en los carcinomas del tracto digestivo y de próstata mientras que la vitamina A disminuye (p<0.05) en los carcinomas digestivos. Estos resultados sugieren que la disminución del Zn y de VA en el suero es un signo general de cáncer y la posibilidad de la existencia de una carencia de estos micronutrientes, que deberá ser investigadas en estudios futuros. Por consiguiente, las estrategias para el mejoramiento del estado nutricional del Zn y de la VA, y de otros micronutrientes, mejorarán la calidad de vida de estos pacientes

HPLC determination of Vitamin D(3) and its metabolite in human plasma with on-line sample cleanup.

A HPLC method with automated column switching and UV-diode array detection is described for the simultaneous determination of Vitamin D(3) and 25-hydroxyvitamin D(3) (25-OH-D(3)) in a sample of human plasma. The system uses a BioTrap precolumn for the on-line sample cleanup. A sample of 1ml of human plasma was treated with 2ml of a mixture of ethanol-acetonitrile (2:1 (v/v)). Following centrifugation, the supernatant was evaporated to dryness under a stream of dry and pure nitrogen. The residue was reconstituted in 250muL of a solution of methanol 5mmoll(-1) phosphate buffer, pH 6.5 (4:1 (v/v)), and a 200mul aliquot of this solution was injected onto the BioTrap precolumn. After washing during 5min with a mobile phase constituted by a solution of 6% acetonitrile in 5mmoll(-1) phosphate buffer, pH 6.5 (extraction mobile phase), the retained analytes were then transferred to the analytical column in the backflush mode. The analytical separation was then performed by reverse-phase chromatography in the gradient elution mode with the solvents A and B (Solvent A: acetonitrile-phosphate buffer 5mmoll(-1), pH 6.5; 20:80 (v/v); solvent B: methanol-acetonitrile-tetrahydrofuran, 65:20:15 (v/v)). The compounds of interest were detected at 265nm. The method was linear in the range 3.0-32.0ngml(-1) with a limit of quantification of 3.0ngml(-1). Quantitative recoveries from spiked plasma samples were between 91.0 and 98.0%. In all cases, the coefficient of variation (CV) of the intra-day and inter-day-assay precision was

[Effect of copper supplementation on lipid profile of Venezuelan hyperlipemic patients]. / Efecto de la suplementación oral con cobre en el perfil lipídico de pacientes Venezolanos hiperlipémicos.

It has been assumed that most Western diets satisfy the requirement of copper/day because of ubiquitous presence of this element in most foods. Recent studies have shown that dietary copper (Cu) may often fall below the estimated daily requirements, what could determine a deficiency of this trace element. This deficiency is associated with hypercholesterolemia and hypertrigliceridemia, both in human and experimental animals. In the present intervention study was examined the effect of the administration of 5 mg of Cu/day in 73 patients (treated group), of both genders, with ages between 26 and 48 years, with high serum levels of total cholesterol and triglycerides without pharmacological treatment and compared with 73 hyperlipemic subjects non-treated with copper (control group) who were matched by gender, age, body weight, smoking habits, calories and fat intake, and physical activity. Before copper administration, a sample of blood was obtained for serum determinations of copper, zinc and lipids. At the end of the experimental period (45 days), a new sample of blood was taken for the corresponding determinations. The results suggest the existence of a marginal deficiency of the trace element in 38% of the subjects and demonstrate that copper supplementation decreases (p < 0.05) serum levels of total cholesterol (r = -0.976), triglycerides (r = -0.972), LDL-cholesterol (r = -0.961) and zinc (r = -0.980) with a slight increment (r = 0.894) of HDL-cholesterol. These findings demonstrate that copper can be used in the treatment of the patients with hypercholesterolemia and hypertriglyceridemia. The mechanisms by which Cu determines these changes are not known.

[Effect of cooper supplementation on blood pressure values in patients with stable moderate hypertension]. / Efecto de la suplementación con cobre sobre los valores de presión arterial en pacientes con hipertensión moderada estable.

Copper (Cu) deficiency is associated with changes in arterial pressure. The effect depends of the age of initiation of the copper-deficient diet. Copper deficiency started at a young age causes hypotension. When initiated in older or adult animals, copper deficiency can cause hypertension. A case-control study was carried out to investigate the effect of administrating 5 mg Cu/d in 60 subjects, both genders, with mild stable hypertension, pharmacologically untreated (treated group) and compared with 60 hypertensives (control group) who were matched by gender, age, body weight, smoking habits, calories, fat and salt intake (NaCl), and physical activity. Hypertension was diagnosed when the blood pressure was > 150/95 mm Hg. Mean age, mean corporal weight and risk factors were similar in both groups. The results suggested the existence of a marginal deficiency of the trace element in 62% of subjects and demonstrated that Cu decreases systolic (r = -0.963) and diastolic (r = -0.981) blood pressures in treated group (p < 0.05). Control patients did not show significant changes in their arterial pressures. These findings indicate a functional alteration in human blood pressure regulation during mild copper depletion and suggest that Cu could be used in the treatment of stable moderate arterial hypertension. Further investigation is needed to determine the extent of this influence.

Efecto de la suplementación con cobre sobre los valores de presión arterial en pacientes con hipertensión moderada estable / Effect of cooper supplementation on blood pressure values in patients with stable moderate hypertension

Copper (Cu) deficiency is associated with changes in arterial pressure. The effect depends of the age of initiation of the copper-deficient diet. Copper deficiency started at a young age causes hypotension. When initiated in older or adult animals, copper deficiency can cause hypertension. A case-control study was carried out to investigate the effect of administrating 5 mg Cu/d in 60 subjects, both genders, with mild stable hypertension, pharmacologically untreated (treated group) and compared with 60 hypertensives (control group) who were matched by gender, age, body weight, smoking habits, calories, fat and salt intake (NaCl), and physical activity. Hypertension was diagnosed when the blood pressure was > 150/95 mm Hg. Mean age, mean corporal weight and risk factors were similar in both groups. The results suggested the existence of a marginal deficiency of the trace element in 62 per cent of subjects and demonstrated that Cu decreases systolic (r = -0.963) and diastolic (r = -0.981) blood pressures in treated group (p < 0.05). Control patients did not show significant changes in their arterial pressures. These findings indicate a functional alteration in human blood pressure regulation during mild copper depletion and suggest that Cu could be used in the treatment of stable moderate arterial hypertension. Further investigation is needed to determine the extent of this influence.

A three-dimensional numerical simulation of mandible fracture reduction with screwed miniplates.

A three-dimensional finite element model of a fractured human mandible treated with plating technique was developed to simulate and to study the biomechanical loads and the stress field distribution. Biomechanical properties of bone have been thoroughly investigated experimentally. In this work, using the finite element method, complete clinical conditions (after surgical reduction, post-operatory period, complete healing period) were simulated. The mandible fracture was located in the symphysis region and one or two titanium miniplates, fixed with monocortical screws, were evaluated. The behaviour of a reduced human mandible with screwed miniplates, as well as its complete healing, is investigated and described.

Determination of paraquat in human blood plasma using reversed-phase ion-pair high-performance liquid chromatography with direct sample injection.

This report describes the determination of paraquat (PQ) in human blood plasma samples by a direct-injection reversed-phase ion-pair chromatographic method. Blood plasma filtrate was injected directly into the LiChrospher(R) RP-18 alkyl-diol silica (ADS) precolumn integrated in a column switching system using a mixture of 3% 2-propanol and 10 mM sodium octane sulfonate (SOS) in a 0.05 M phosphate buffer (pH 2.8). After washing with this phase, the ADS precolumn was back-flushed with the analytical mobile phase consisting of 40% of methanol and 10 mM SOS in a 0.05 M phosphate buffer (pH 2.8) at a flow rate of 1.0 ml min(-1), in order to carry the analyte to a conventional reversed-phase analytical column, where the separation of PQ was achieved and finally detected by UV at 258 nm. The recoveries of PQ from human blood plasma samples ranged between 95.0 and 99.5% at nine different concentrations (from 0.05 to 3.00 microg of PQ ml(-1)) with coefficients of variation <2.5% (n=3). The precision expressed as relative standard deviation was below 3.5% for between-day and below 4.3% for within-day measurements (n=5). The detection limit (signal-to-noise ratio, S/N>3) was 0.005 microg ml(-1) with an injection volume of 200 microl. The proposed method is promising for the identification and quantification of PQ at low concentration levels and is suitable for its analysis in human blood plasma samples from intentional or accidental poisonings cases with a sample throughput of 5 samples per hour.

Flow analysis-hydride generation-Fourier transform infrared spectrometric determination of antimony in pharmaceuticals.

In this work, a flow analysis system with hydride generation and Fourier transform infrared (FTIR) spectrometric detection has been developed for the determination of antimony in pharmaceuticals. The method is based on the on-line mineralization/oxidation of the organic antimonials present in the sample and pre-reduction of Sb(V) to Sb(III) with K(2)S(2)O(8) and KI, respectively; prior to the stibine generation. The gaseous SbH(3) is separated from the solution in a gas phase separator, and transported by means of a nitrogen carrier into a short pathway (10 cm) IR gas cell, where the corresponding FTIR spectrum is acquired by accumulating 3 scans in a continuous mode. The 1893 cm(-1) band was used for the quantification of the antimony. The procedure is carried out in a closed system, which reduces sample handling and makes possible the complete automation of the antimony determination. The figures of merit of the proposed method (linear range: 0-600 mg l(-1), limit of detection (3sigma)=0.9 mg l(-1), limit of quantification (10sigma)=3 mg Sb l(-1), precision (R.S.D.) less than 1% and sample frequency=28 h(-1)), are appropriate for the designed application. Furthermore, precise and accurate results were found for the analysis of different antimonial pharmaceutical samples, indicating that the methodology developed represents a valid alternative for the determination of antimony in pharmaceuticals, which could be suitable for the routine control analysis.

Column-switching high-performance liquid chromatographic analysis of carbamazepine and its principal metabolite in human plasma with direct sample injection using an alkyl-diol silica (ADS) precolumn.

In this paper, the on-line coupling of solid-phase extraction, based on a restricted-access support with high-performance reverse phase chromatography for the analysis of carbamazepine (CBZ) and carbamazepine-10,11-epoxide (CBZ-E) in human plasma samples is described. A precolumn packed with 25 mum C(18) alkyl-diol support is used for direct plasma injection. Using column-switching techniques, the analytes were enriched on the precolumn by a 5 mM phosphate buffer (pH 7) with 2% of methanol solution at a flow-rate of 0.8 ml min(-1), while proteins and endogenous hydrophilic substances in plasma were washed off to waste. The enriched analytes were then back-flushed onto the analytical C(18) column, separated by a mixture of 10 mM phosphate buffer (pH 7) acetonitrile (70:30 v/v) solution at a flow-rate of 1.0 ml min(-1) and detected by the ultraviolet absorbance set at 212 and 285 nm and without transfer loss. Linear calibration graphs were obtained for sample injection volumes of 50 (0.2-4.0 of mug of CBZ ml(-1) and 0.1-5.0 mug of CBZ-E ml(-1), respectively), and 20 mul (5.0-20.0 mug of CBZ ml(-1)); in either case the r-value was >0.9963. Recoveries from spiked plasma samples were quantitative for both analytes and the coefficients of variation were below 3.83%. The lowest samples concentrations that can be quantified with acceptable accuracy and precision was 0.2 mug CBZ ml(-1) and 0.1 mug CBZ-E ml(-1) when a sample volume of 50 mul was injected. Concentrations of 0.08 and 0.05 mug ml(-1) of CBZ and CBZ-E were considered the limit of detection for a signal-to-noise ratio of 3. Furthermore, the developed column-switching method was successfully applied to the determination of CBZ and CBZ-E in plasma samples of patients submitted to CBZ therapy.

A flow injection-ETAAS system for the on-line determination of total and dissolved silica in waters.

In this work total (Si-tot) and 'soluble' or reactive (Si-sol) concentrations of silicon in natural and tap waters were sequentially determined by electrothermal atomic absorption spectrometry (ETAAS). First, samples were on-line diluted based on the merging-zone principle in order to allow the determination of Si-tot within the 300-1000 mugSil(-1) range. After the dilution process, a sub-sample was collected in the capillary of a sampling arm assembly (SAA). Thereafter, samples were subject to a precipitation/dissolution process in order to allow the determination of Si-sol within the 280-850 mugSil(-1). Si-sol was precipitated with ammonium chloride and collected on the walls of a knotted coil. The precipitate was dissolved with ammonium molybdate in an acidic medium (HNO(3)) and a sub-sample was then collected in the SAA. In both cases, 10 mul volumes of the sub-sample were injected into the atomizer with the previous introduction of 20 ng of Eu as chemical modifier (10 mul) by the spectrometer autosampler. The recovery values obtained with natural waters spiked samples were over 46% and the agreement between observed and certified samples values was good. The proportion of Si-sol in comparison with the Si-tot was high (85-95%) in most natural waters. The precision of the method was 2.4-3.5 and 4.5-6.2% (n=10) for the determination of Si-tot and Si-sol, respectively.

An on-line flow-injection microwave-assisted mineralization and a precipitation/dissolution system for the determination of molybdenum in blood serum and whole blood by electrothermal atomic absorption spectrometry.

An on-line flow injection (FI) precipitation-dissolution system with microwave-assisted sample digestion has been developed for the electrothermal atomic absorption spectrometry (ETAAS) determination of trace or ultratrace amounts of molybdenum in human blood serum and whole blood samples. After the exposure of the sample to microwave radiation, the on-line precipitation of molybdenum was achieved by the merging-zone of a 0.5-ml plug of sample with a plug of potassium ferrocyanide, which were carried downstream with a solution of 0.5 mol l(-1) of HNO(3). The interfering effects of iron and copper were minimized by the introduction of a flow of a 5% (w/v) sodium potassium tartrate (for iron) and 2% (w/v) of thiourea (for copper and zinc) in a 5% (v/v) ammonia and 2% (v/v) ammonium chloride solution previous to the precipitation reaction. The reddish-brown precipitate of molybdenyl ferrocyanide was collected on the walls of a knotted reactor. The precipitate was dissolved with the introduction of 1 ml of a 3.0 mol l(-1) NaOH solution and the best performance in terms of detection limit and precision was achieved when a sub-sample of 140 mul was collected in a capillary of a sampling arm assembly, to introduce 20 mul volumes into the atomizer by means of positive displacement with air through a time-based injector. A detection limit (3sigma) of 0.1 mug Mo l(-1) using an aqueous standard solution was obtained. The method is quantitative and is applied over the range 0.2-20.0 mug Mo l(-1). The precision of the method evaluated by ten replicate analyses of aqueous standard solutions containing 0.5 and 1.0 mug Mo l(-1) was 2.8 and 3.1% (relative standard deviation, RSD) (for n=5), respectively. Whereas, the precision evaluated by five replicate analysis of a serum and a whole blood sample were 3.3 and 3.8% RSD. An enrichment factor of ca. 3.5 was achieved with the introduction of 0.5 ml aqueous standard solutions at a sample flow rate of 1.0 ml min(-1). Recoveries of spiked molybdenum in blood serum and whole blood were in the ranges 96-102 and 94-98%, respectively. The results obtained for two human whole blood certified reference materials were in good agreement with the indicative values.

Relationships between heart rate variability, functional capacity, and left ventricular function following myocardial infarction: an evaluation after one week and six months.

BACKGROUND: Relationships between heart rate (HR) variability and different prognostic markers such as ejection fraction, functional capacity, and patency of the infarct-related artery, as well as the comparison of their time courses are not fully elucidated. HYPOTHESIS: The aim of study was to assess prospectively the early postinfarction changes in HR variability and its evolution over a period of 6 months: the relationships between HR variability and functional capacity in exercise testing; left ventricular function in cardiac catheterization: status of the infarct-related artery; and the comparison of their time courses. METHODS: In 42 patients with anterior myocardial infarction, a study was made of the early changes in HR variability analyzed by the complex demodulation method, its evolution over a period of 6 months. and the relationships between HR variability and (1) functional capacity in exercise testing, (2) left ventricular function in cardiac catheterization, and (3) status of the infarct-related artery. RESULTS: At 1 week HR variability parameters correlated directly with functional capacity indicators such as METS, percent change in HR from rest to peak exercise (%deltaHR), difference between initial and peak HR (HR range), percent peak theoretical HR (% peak HR), left ventricular ejection fraction (EF), and, inversely, with end-systolic volume (ESV). Stepwise multiple regression analysis to establish HR variability parameters (recorded at 1 week) as related to functional capacity and left ventricular function at 1 week and 6 months postinfarction established the following variables: (1) At 1 week: standard deviation (SD) of the RR cycles in relation to %deltaHR (r = 0.60, p <0.0001), HR range (r = 0.43, p < 0.01), and EF (r = 0.79, p < 0.0001). (2) At 6 months, the sole accepted HR variability parameter was the SD in relation to %deltaHR (r = 0.38, p < 0.05) and HR range (r = 0.45, p < 0.01). No variability parameter was accepted in relation to METS, % peak HR, or ESV. Relationship between EF or ESV and HR variability parameters was not significant when both were evaluated at 6 months. At that time, there was a significant increase in all HR variability parameters among all surviving patients (n = 39), with the exception of the LF/HF ratio and mean RR cycle. The percent increase in HR variability between the first week and 6 months was greater among those patients with the lowest basal EF. No relation was established between HR variability and patency of the infarct-related artery. CONCLUSION: The decrease in HR variability observed following myocardial infarction is associated with a diminished functional capacity and an increased alteration of the EF. This does not affect the recovery of HR variability, which was observed in all surviving patients.

On-line determination of antimony(III) and antimony(V) in liver tissue and whole blood by flow injection - hydride generation - atomic absorption spectrometry.

A new analytical procedure for the speciation of antimony in liver tissues is presented here. For this purpose, a flow injection system has been developed for the treatment of samples and the determination of antimony by hydride generation - atomic absorption spectrometry. The method involves the sequential and the on-line extraction of antimony(III) and antimony(V) from solid lyophilized blood and hamsters liver tissues, with 1.5 mol l(-1) acetic acid and 0.5 mol l(-1) sulfuric acid for Sb(III) and Sb(V), respectively. Reduction of Sb(V) to Sb(III) for stibine generation is effected by the on-line pre-reduction with l-cysteine. The linear ranges were 2.5-20 and 1.0-25 mug l(-1) of Sb(III) and Sb(V), respectively. The detection limits (3sigma) were 1.0 mug l(-1) for Sb(III) and 0.5 mug l(-1) for Sb(V). The relative standard deviation values for fifteen independent measurements were 2.1 and 1.8% for Sb(III) and Sb(V), respectively. The recovery studies performed with samples of cattle liver provided results from 98 to 100% for Sb(III) and from 100 to 103% for Sb(V) for samples spiked with single species. For samples spiked with both Sb(III) and Sb(V), the recovery varied from 97 to 103% for Sb(III) and from 101 to 103% for Sb(V).

Endocrine effects of lithium carbonate in healthy premenopausal women: relationship with body weight regulation.

The mechanisms involved in Li-induced weight gain remain unclear. The higher frequency of obesity in women than in men under Li treatment, suggests a role for reproductive hormones. The serum levels of the following hormones were evaluated in healthy young women at diverse stages of a control menstrual cycle, and during Li carbonate (900 mg/day) or placebo administration: prolactin, luteinizing hormone, follicle-stimulating hormone, 17-1 estradiol, progesterone, thyroxine, thyrotropin, cortisol, dehidroepiandrosterone sulfate, free testosterone, leptin and an oral glucose tolerance test, in order to measure the areas under the glucose and insulin curve. The body weight was assessed the day before and the last day of treatment. The Li serum levels 15 hours after the last dose were 0.31 +/- 0.1 mEq/L. No significant changes in body weight and in the normal fluctuations of the reproductive hormones along the menstrual cycle were observed during Li administration. An increase in the serum levels of thyrotropic hormone ( p = 0.0001) was the only significant effect of Li, which may predispose to excessive weight gain after prolonged administration of the cation. The remarkable lack of effects of Li on these hormones, question the pertinence of studies conducted in healthy volunteers for the comprehension of the obesity observed in psychiatric patients who may be particularly prone to gain weight under prolonged treatment with high dose of Li.

A 3d-fem Simulation of Highest Stress Lines in Mandible Fractures by Elastic Impact.

In this article, the more usual mandible fracture areas are located by identifying the highest stress lines using a three-dimensional (tetrahedral) finite element method. By taking into account the temporomandibular contact and the inertia effects, the mathematical model is considered to be a dynamic Signorini's problem, that is, a dynamic variational inequality which is discretized in time following Newmark's method. So, in each time step a stationary variational inequality is solved by a penalty-duality algorithm. Finally, some numerical results obtained by simulating the more usual fractures in the human mandible are presented and compared with clinical experimental information.

Determination of beryllium in natural and waste waters using on-line flow-injection preconcentration by precipitation/dissolution for electrothermal atomic absorption spectrometry.

A flow injection (FI) on-line precipitation-dissolution was developed for electrothermal atomic absorption spectrometry (ETAAS) determination of (ultra)trace amounts of beryllium in water samples. Beryllium was precipitated quantitatively with NH(4)OH+NH(4)Cl and collected in a knotted tube of Tygon without using a filter, while the other matrix components flowed downstream to waste. The precipitate was dissolved with nitric acid and a sub-sample was collected in a capillary of a sampling arm assembly, to introduce 10 mul volumes into the graphite tube by means of positive displacement with air through a time-based injector. This sequence was timed to synchronize with the previous introduction of 6 mug of Lu (in 20 mul) by the spectrometer autosampler. The effect of a number of possible cations on the beryllium precipitation process was studied. While, the addition of Ba(2+), Sr(2+), Ca(2+), Mg(2+), Mn(2+), Zn(2+), Co(2+) and Ni(2+) did not produce any perceptible precipitate on the reaction coil walls, the addition of Al(3+), Cr(3+) and Fe(3+) produced large precipitated particles. However, their tolerance limit was well above the levels at which theses species are commonly found in most natural waters. The detection limit (3sigma) of 25 ng l(-1) in the sample solution was obtained. The precision of the method, evaluated by ten replicate analyses of solutions containing 20 and 200 pg of beryllium were 4.8 and 4.0% (n=5), respectively. Enrichment factors from 7.0 to 10.3 and from 10.5 to 13.8 were obtained for precipitation times from 25 to 38 s and from 43 to 50 s for waste and tap waters, respectively. These results indicate that the enrichment factor was limited by the interference of some matrix metals which could precipitate as hydroxides (or related species) and be retained in the reaction coil. The integrated system permits fully automated operation, avoiding time-consuming manual work and enhancing the reproducibility and precision of the determination of beryllium. The results obtained for the determination of beryllium in certified reference materials (trace elements in water), together with the good recovery of spiked analytes, demonstrate the applicability of the procedure to the analysis of natural waters.

Sequential determination of Se(IV) and Se(VI) by flow injection-hydride generation-atomic absorption spectrometry with HCl/HBr microwave aided pre-reduction of Se(VI) to Se(IV).

In this study a flow injection (FI) system used in conjunction with hydride generation (HG), atomic absorption spectrometry (AAS) and microwave (MW) aided pre-reduction of selenite (Se(IV)) to selenate (Se(IV)) with HCl:HBr has been developed in order to differentiate both inorganic selenium species. As full control of the MW reduction step is possible, the experimental approach allows the use of milder acidic conditions (10% v/v of HCl and HBr) than those conventionally accomplished with hydrochloric acid alone (>/=50% v/v). Experimental parameters were optimized by the univariate optimization method. In either case, the linear range was from 1.0 to 30 mug l(-1). The detection limits based on 3sigma of the blank signal were 0.25 mug l(-1) for Se(IV) and 0.30 mug l(-1) for Se(VI). The reproducibility, about 3% RSD and recoveries of different amounts of Se(VI) and Se(IV) added to water and orange juice samples (97-103%) were good. The main advantage of the proposed method is that the sequential determination of Se(IV) and Se(VI) is performed at a high sampling frequency (ca. 50 samples per h) in a closed system without Se losses, and with a minimum sample waste, operator attention, and sample manipulation.