Crack propagation and fracture in silicon wafers under thermal stress

The behaviour of microcracks in silicon during thermal annealing has been studied using in situ X-ray diffraction imaging. Initial cracks are produced with an indenter at the edge of a conventional Si wafer, which was heated under temperature gradients to produce thermal stress. At temperatures where Si is still in the brittle regime, the strain may accumulate if a microcrack is pinned. If a critical value is exceeded either a new or a longer crack will be formed, which results with high probability in wafer breakage. The strain reduces most efficiently by forming (hhl) or (hkl) crack planes of high energy instead of the expected low-energy cleavage planes like {111}. Dangerous cracks, which become active during heat treatment and may shatter the whole wafer, can be identified from diffraction images simply by measuring the geometrical dimensions of the strain-related contrast around the crack tip. Once the plastic regime at higher temperature is reached, strain is reduced by generating dislocation loops and slip bands and no wafer breakage occurs. There is only a small temperature window within which crack propagation is possible during rapid annealing

Observation of nano-indent induced strain fields and dislocation generation in silicon wafers using micro-raman spectroscopy and white beam x-ray topography

In the semiconductor manufacturing industry, wafer handling introduces micro-cracks at the wafer edge. During heat treatment these can produce larger, long-range cracks in the wafer which can cause wafer breakage during manufacture. Two complimentary techniques, micro-Raman spectroscopy (μRS) and White Beam Synchrotron X-ray Topography (WBSXRT) were employed to study both the micro-cracks and the associated strain fields produced by nano-indentations in Si wafers, which were used as a means of introducing controlled strain in the wafers. It is shown that both the spatial lateral and depth distribution of these long range strain fields are relatively isotropic in nature. The Raman spectra suggest the presence of a region under tensile strain beneath the indents, which can indicate a crack beneath the indent and the data strongly suggests that there exists a minimum critical applied load below which cracking will not initiate

Asociación entre variantes genéticas relacionadas con el metabolismo lipídico y energético y la pérdida de peso tras una intervención en adolescentes con sobrepeso u obesidad

Background: Some SNPs related to lipid and energy metabolism may be implicated not only in the development of obesity and associated comorbidities, but also in the weight loss response after a nutritional intervention. Objective: In this context, the present study analyzed four SNPs located within four genes known to be associated with obesity and other obesity-related complications, and their putative role in a weight-loss intervention in overweight/obese adolescents. Methods: The study population consisted of 199 overweight/obese adolescents (13-16 yr old) undergoing 10 weeks of a weight loss multidisciplinary intervention: the EVASYON programme (www.estudioevasyon.org). Adolescents were genotyped for 4 SNPs, and anthropometric measurements and biochemical markers were analyzed at the beginning and after the intervention. Results: Interestingly, APOA5(rs662799) was associated with the baseline anthropometric and biochemical outcomes, whereas FTO (rs9939609) seemed to be related with the change of these values after the 10-week intervention. The other two SNPs, located in the CETP (rs1800777) and the APOA1 (rs670) genes, showed important relationships with adiposity markers. Specifically, a combined model including both SNPs turned up to explain up to 24% of BMI-SDS change after 10 weeks of the multidisciplinary intervention, which may contribute to under - stand the weight loss response. Conclusion: Common variants in genes related to lipid and energy metabolism may influence not only biochemical outcomes but also weight loss response after a multidisciplinary intervention carried out in obese/overweight adolescents..Antecedentes: Algunas variantes genéticas relacionadas con el metabolismo lipídico y energético pueden estar implicadas en la respuesta a una intervención nutricional además de estar asociadas con el desarrollo de obesidad y comorbilidades asociadas. Objetivo: En este sentido, este artículo analiza cuatro polimorfismos situados en cuatro genes que han sido previamente asociados con la obesidad u otras complicaciones asociadas a la misma, así como su posible papel en la respuesta a una intervención para la pérdida de peso en adolescentes con sobrepeso u obesidad. Métodos: La población en estudio está formada por 199 adolescentes con sobrepeso u obesidad (13-16 años) llevando a cabo una intervención multidisciplinar de 10 semanas para la pérdida de peso: programa EVASYON (www.estudioevasyon.org). Los adolescentes fueron genotipados para los 4 SNPs y tanto al comienzo como al final de la intervención se analizaron marcadores bioquímicos y se tomaron medidas antropométricas. Resultados: Rs662799 del gen APOA5 se asoció al inicio con parámetros antropométricos y bioquímicos, mientras que el rs9939609 del gen FTO parecía estar asociado con el cambio de estas variables tras 10 semanas de intervención. Las variantes rs1800777 del gen CETP y rs670 del gen APOA1 mostraron una importante asociación con marcadores de adiposidad. Concretamente, un modelo combinado incluyendo los dos polimorfismos logró explicar hasta un 24% del cambio en el IMC-SDS tras 10 semanas de intervención. Conclusión: Variantes genéticas previamente relacionadas con el metabolismo lipídico y energético, pueden repercutir no solamente en valores bioquímicos sino también en la respuesta a una intervención multidisciplinar para la pérdida de peso en adolescentes con sobrepeso u obesidad.Research relating to this abstract was funded by grants from the Health Research Fund from the Carlos III Health Institute from Ministry of Health and Consumption, FIS (PI051579, PI051080) for the EVASYON project, Línea Especial, Nutrición y Obesidad (University of Navarra), CIBERobn and RETICS (Gob Navarra). The scholarships to A. Moleres from the Navarra Government is fully acknowledged

Changes in plasma fatty acid composition are associated with improvements in obesity and related metabolic disorders: A therapeutic approach to overweight adolescents

Background & aims: In recent years, obesity has reached alarming levels among children and adolescents. The study of plasma fatty acid (FA) composition, as a reflection of diet, and its associations with other parameters, that are closely linked to obesity and the cardiometabolic profile, may be useful for setting nutritional goals for obesity treatment and prevention. This study explored the relationship between plasma FA levels and body fat and cardiometabolic risk markers, in overweight adolescents. Methods: A multidisciplinary weight loss program was followed by 127 overweight and obese adolescents aged 12-17 years old. Plasma FA composition, anthropometric indicators of adiposity and biochemical parameters were analyzed at baseline, two months (the end of the intensive intervention phase) and six months (the end of the extensive phase). Results: While saturated fatty acid (SFA) and n-6 polyunsaturated fatty acid (PUFA) levels decreased significantly during the intervention, monounsaturated fatty acid (MUFA) and n-3 PUFA showed the opposite trend. The decrease in SFA C14:0 was associated with a reduction in total and LDL cholesterol, apolipoprotein B and insulin. The increase in MUFAs, especially C18:1n-9, was related to a reduction in weight, fat mass, fat mass index and glucose. Regarding PUFAs, changes in the n-3 series were not associated with any of the parameters studied, whereas the reduction in n-6 PUFA5 was directly related to weight, fat mass, total and HDL cholesterol, apolipoprotein Al, glucose and insulin, and inversely associated with diastolic blood pressure. The adolescents with greater weight loss presented significant changes in MUFAs, n-6 PUFA5 and C14:0. Conclusions: Modifications in plasma FA composition were associated with adiposity reduction and cardiometabolic profile improvement in an anti-obesity program aimed at adolescents. The changes observed in FA composition were related to the success of the treatment, since the individuals most affected by these variations were those who presented the greatest weight loss

Relation between plasma antioxidant vitamin levels, adiposity and cardio-metabolic profile in adolescents: Effects of a multidisciplinary obesity programme

Background & aims In vivo and in vitro evidence suggests that antioxidant vitamins and carotenoids may be key factors in the treatment and prevention of obesity and obesity-associated disorders. Hence, the objective of the present study was to determine the relationship between plasma lipid-soluble antioxidant vitamin and carotenoid levels and adiposity and cardio-metabolic risk markers in overweight and obese adolescents participating in a multidisciplinary weight loss programme. Methods A therapeutic programme was conducted with 103 adolescents aged 12–17 years old and diagnosed with overweight or obesity. Plasma concentrations of a-tocopherol, retinol, ß-carotene and lycopene, anthropometric indicators of general and central adiposity, blood pressure and biochemical parameters were analysed at baseline and at 2 and 6 months of treatment. Results Lipid-corrected retinol (P < 0.05), ß-carotene (P = 0.001) and a-tocopherol (P < 0.001) plasma levels increased significantly, whereas lipid-corrected lycopene levels remained unaltered during the treatment. Anthropometric indicators of adiposity (P < 0.001), blood pressure (P < 0.01) and biochemical parameters (P < 0.05) decreased significantly, whereas fat free mass increased significantly (P < 0.001). These clinical and biochemical improvements were related to changes in plasma lipid-corrected antioxidant vitamin and carotenoid levels. The adolescents who experienced the greatest weight loss also showed the largest decrease in anthropometric indicators of adiposity and biochemical parameters and the highest increase in fat free mass. Weight loss in these adolescents was related to an increase in plasma levels of lipid-corrected a-tocopherol (P = 0.001), ß-carotene (P = 0.034) and lycopene (P = 0.019). Conclusions Plasma lipid-soluble antioxidant vitamin and carotenoid levels are associated with reduced adiposity, greater weight loss and an improved cardio-metabolic profile in overweight and obese adolescents

Valoración del cambio de composición corporal en adolescentes con sobrepeso y obesidad incluidos en un tratamiento multidisciplinar: Estudio EVASYON

La adolescencia se considera una etapa vulnerable desde el punto de vista nutricional. La obesidad en la infancia y adolescencia se considera una enfermedad compleja, que preocupa tanto a padres como a profesionales sanitaros debido a su alta prevalencia y a sus consecuencias en la edad adulta. Por ello, los objetivos generales de este trabajo son: 1) valorar los índices antropométricos sencillos como predictores de los cambios de grasa corporal, empleando absorciometría dual de rayos X como método de referencia; 2) identificar los predictores cognitivos y conductuales del abandono de un estudio de intervención, y calcular la tasa de abandono; 3) valorar los cambios de composición corporal en niños y adolescentes, empleando diferentes métodos de composición corporal; y 4) valorar si el cumplimiento de la intervención dietética y el índice de calidad de la dieta son predictores de los cambios de composición corporal durante un seguimiento de 13 meses de una intervención multidisciplinar..

Design and evaluation of a treatment programme for Spanish adolescents with overweight and obesity. The EVASYON Study

<p>Abstract</p> <p>Background</p> <p>The prevalence of overweight and obesity (OW/OB) among adolescents worldwide has increased since the 60 s. Spain has reached one of the highest OW/OB prevalence rates among adolescents from European countries. The aim of this methodological paper is to describe the design and evaluation in the EVASYON study (Development, implementation and evaluation of the efficacy of a therapeutic programme for adolescents with OW/OB: integral education on nutrition and physical activity).</p> <p>Methods/Design</p> <p>The EVASYON was planned by a multidisciplinary team to treat OW/OB in Spanish adolescents. The EVASYON is a multi-centre study conducted in 5 hospitals in 5 Spanish cities (Granada, Madrid, Pamplona, Santander and Zaragoza) and two hundred and four OW/OB Spanish adolescents were recruited for this intervention. The treatment was implemented for approximately one-year follow-up. The adolescents were treated in groups of a maximum of 10 subjects; each group had 20 visits during the treatment period in two phases: intensive during the first 2 months (1^stto 9^thvisits), and extensive during the last 11 months (10^thto 20^thvisits). In order to assess the efficacy of the treatment, 8 dimensions were measured: diet; physical activity and fitness; eating behaviour; body composition; haematological profile; metabolic profile; minerals and vitamins; immuno-inflammatory markers. Moreover, genetic polymorphisms were also determined.</p> <p>Discussion</p> <p>The treatment programme developed in the EVASYON study was designed as a national pilot study to be implemented as an effective treatment for adolescents with OW/OB into the Spanish Health Care Service.</p

Design and evaluation of a treatment programme for Spanish adolescents with overweight and obesity. The EVASYON Study

Background The prevalence of overweight and obesity (OW/OB) among adolescents worldwide has increased since the 60 s. Spain has reached one of the highest OW/OB prevalence rates among adolescents from European countries. The aim of this methodological paper is to describe the design and evaluation in the EVASYON study (Development, implementation and evaluation of the efficacy of a therapeutic programme for adolescents with OW/OB: integral education on nutrition and physical activity). Methods/Design The EVASYON was planned by a multidisciplinary team to treat OW/OB in Spanish adolescents. The EVASYON is a multi-centre study conducted in 5 hospitals in 5 Spanish cities (Granada, Madrid, Pamplona, Santander and Zaragoza) and two hundred and four OW/OB Spanish adolescents were recruited for this intervention. The treatment was implemented for approximately one-year follow-up. The adolescents were treated in groups of a maximum of 10 subjects; each group had 20 visits during the treatment period in two phases: intensive during the first 2 months (1st to 9th visits), and extensive during the last 11 months (10th to 20th visits). In order to assess the efficacy of the treatment, 8 dimensions were measured: diet; physical activity and fitness; eating behaviour; body composition; haematological profile; metabolic profile; minerals and vitamins; immuno-inflammatory markers. Moreover, genetic polymorphisms were also determined. Discussion The treatment programme developed in the EVASYON study was designed as a national pilot study to be implemented as an effective treatment for adolescents with OW/OB into the Spanish Health Care Service

An Organic Spin Crossover Material in Water from a Covalently Linked Radical Dyad

A covalently linked viologen radical cation dyad acts as a reversible thermomagnetic switch in water. Cycling between diamagnetic and paramagnetic forms by heating and cooling is accompanied by changes in optical and magnetic properties with high radical fidelity. Thermomagnetic switches in water may eventually find use as novel biological thermometers and in temperature-responsive organic materials where the changes in properties originate from a change in electronic spin configuration rather than a change in structure