131,430 research outputs found
Influenza delle tecniche di sterilizzazione rapida sulle proprietà meccaniche degli strumenti endodontici
No full textR.P.E. y Endor en (Gd,Bi)2 Mg3 (NO3)12 . 24 H2O
No full textEste trabajo está relacionado con las medidas de los parámetros del hamiltoniano de spin para el caso del 155Cd+++ y 157Cd+++ en Bi2 Mg3 (N03)12 24H2O. Con tal fin fueron usadas técnicas de resonancia paramagnética electrónica y ENDOR(Electron Nuclear double resonance). Fue utilizado un hamiltoniano generalizado incluyendo términos Zeeman e interacción hiperfina de orden superior. Este hamiltoniano fue diagonalizado por medio de un programa decomputadora. La separación espectroscópica de campo cero fue calculada teóricamente y comparada con el valor experimental.Fil: Butti, Carlos Horacio. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina
R.P.E. y Endor en (Gd,Bi)2 Mg3 (NO3)12 . 24 H2O
No full textEste trabajo está relacionado con las medidas de los parámetros del hamiltoniano de spin para el caso del 155Cd+++ y 157Cd+++ en Bi2 Mg3 (N03)12 24H2O. Con tal fin fueron usadas técnicas de resonancia paramagnética electrónica y ENDOR(Electron Nuclear double resonance). Fue utilizado un hamiltoniano generalizado incluyendo términos Zeeman e interacción hiperfina de orden superior. Este hamiltoniano fue diagonalizado por medio de un programa decomputadora. La separación espectroscópica de campo cero fue calculada teóricamente y comparada con el valor experimental.Fil: Butti, Carlos Horacio. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina
High-throughput, multi-batch system for the efficient microwave digestion of biological samples
No full textIn this paper, we proposed a high-throughput microwave digestion system based on multi-batch reactors (three quartz test tubes inside commercial PTFE vessels). This original configuration was validated by ICP-MS analysis of several elements in biological certified reference materials (fish tissues and plankton). The proposed system was proved to be free from contamination showing very low LODs. The improved hardware configuration is therefore highly beneficial for the detection of trace elements in microsamples from the marine food web
A high-throughput, straightforward procedure for biomonitoring organomercury species in human hair
No full textMercury is a pervasive and concerning pollutant due to its toxicity, mobility, and tendency to biomagnify in aquatic and terrestrial ecosystems. Speciation analysis is crucial to assess exposure and risks associated with mercury, as different mercury species exhibit varying properties and toxicities. This study aimed at developing a selective detection method for organic mercury species in a non-invasive biomonitoring matrix like human hair. The method is based on frontal chromatography (FC) in combination with inductively coupled plasma mass spectrometry (ICP-MS), using a low pressure, homemade, anion exchange column inserted in a standard ICP-MS introduction system, without requiring high-performance liquid chromatography (HPLC) hyphenation. In addition to the extreme simplification and cost reduction of the chromatographic equipment, the proposed protocol involves a fast, streamlined and fully integrated sample preparation process (in contrast to existing methods): the optimized procedure features a 15-min ultrasonic assisted extraction procedure and 5 min analysis time. Consequently, up to 100 samples could be analyzed daily, making the method highly productive and suitable for large-scale screening programs in public and environmental health. Moreover, the optimized procedure enables a limit of detection (LOD) of 5.5 μg/kg for a 10 mg hair microsample. All these features undeniably demonstrate a significant advancement in routine biomonitoring practices. To provide additional evidence, the method was applied to forty-nine human hair samples from individuals with varying dietary habits successfully finding a clear correlation between methylmercury levels (ranging from 0.02 to 3.2 mg/kg) in hair and fish consumption, in line with previous literature data
Biomimetic Orthodontic treatments: preferences of adult patients and analysis of the willingness-to-pay index
No full textOBJECTIVES: Minimal knowledge is available concerning adult patient preferences and evaluations in terms of biomimetic orthodontic treatments. The first objective of this study was to evaluate the degree of acceptance of an orthodontic treatment accomplished with three different highly aesthetic orthodontic appliances: 1) clear removable aligners, group CA; 2) fixed vestibular appliances with aesthetic ceramic brackets, group FV; 3) fixed lingual appliances with customized brackets, group FL. The second objective was to analyse the strength of preference in a Western population of adult patients, expressed according to the Willingness-To-Pay (WTP) method, against an orthodontic treatment delivered with these appliances. MATERIALS AND METHODS: WTP values were recorded in 83 subjects on the basis of a starting bid of 3,000 £ (one year of therapy) modifiable through increases or decreases (100 £). Data were collected through an individually delivered online questionnaire. Specific information and details regarding the appliances were provided by means of an interactive web-area of the survey. Population characteristics and choices, median and WTP values and associations with socio-demographic parameters (Mann-Whitney and Kruskal-Wallis tests), correlations between variables (Chi-square test in contingency tables) and significant parameters for predicting WTP values obtained in a multiple linear regression model were revealed. RESULTS: The visualization of details about "limitations and complications" associated with the use of the three appliances was most frequent (31% of requests); the other two major areas of interest were "duration of therapy" (21%) and "discomfort" (13%). The appliances preferred by patients for treatment were, in decreasing order, CA (51.2%), FL (28.8%) and FV (20%); the recorded WTP median values were 3,500, 3,000 and 2,000 £ for FV, CA and FL respectively; no significant difference was found by comparing medians in the three groups (Wilcoxon test: p = 0.2254). An annual income higher than 30,000 £ and regular dental check-ups (once/year) were positive predictors (p = 0.0167 and p = 0.0020, respectively) of the WTP values (regression analysis). CONCLUSIONS: Over half the investigated population (51.2%) indicated the removable clear aligner as the preferential choice for a biomimetic treatment. Despite the high aesthetic value of CA and FL, patients didn't show a greater willingness to put efforts and money for a treatment specifically accomplished with one of those appliances
Effects of vitamin D and retinoic acid on human glioblastoma cell lines.
No full textThe biological significance of vitamin D receptors expressed by glioblastoma and other glial tumours is still unclear. In an effort to clarify this issue we studied the effects of increasing concentrations of 25-dihydroxyvitamin D3 and its metabolite 1 alpha,25-dihydroxyvitamin D3 on two human glioblastoma cell lines. Both substances were capable of inducing a significant (> 50%) reduction in growth of the two glioblastoma cell lines at dosages over 5 microM. When the HU 70 cell line was treated by increasing dilutions of 25-dihydroxyvitamin D3 combined with 1 microM all trans-retinoic acid, significant inhibition was apparent even after addition of 25-dihydroxyvitamin D3 in the nanomolar range. Reduction of growth index was mainly due to induced cell death. Our results provide in vitro evidence that vitamin D metabolites alone or in combination with retinoids may be potentially useful agents in the differentiation therapy of human malignant gliomas
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