Brown University

About: Brown University is a education organization based out in Providence, Rhode Island, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 35778 authors who have published 90896 publications receiving 4471489 citations. The organization is also known as: brown.edu & Brown.

Fabrication of solid-state nanopores with single-nanometre precision.

Abstract: Single nanometre-sized pores (nanopores) embedded in an insulating membrane are an exciting new class of nanosensors for rapid electrical detection and characterization of biomolecules. Notable examples include α-hemolysin protein nanopores in lipid membranes1,2 and solid-state nanopores3 in Si3N4. Here we report a new technique for fabricating silicon oxide nanopores with single-nanometre precision and direct visual feedback, using state-of-the-art silicon technology and transmission electron microscopy. First, a pore of 20 nm is opened in a silicon membrane by using electron-beam lithography and anisotropic etching. After thermal oxidation, the pore can be reduced to a single-nanometre when it is exposed to a high-energy electron beam. This fluidizes the silicon oxide leading to a shrinking of the small hole due to surface tension. When the electron beam is switched off, the material quenches and retains its shape. This technique dramatically increases the level of control in the fabrication of a wide range of nanodevices.

On the relationship between critical tensile stress and fracture toughness in mild steel

Abstract: SUMMARY AN ANALYSIS is presented which relates the critical value of tensile stress (a,) for unstable cleavage fracture to the fracture toughness (K,,) for a high-nitrogen mild steel under plane strain conditions. The correlation is based on (i) the model for cleavage cracking developed by E. Smith and (ii) accurate plastic*lastic solutions for the stress distributions ahead of a sharp crack derived by J. R. Rice and co-workers. Unstable fracture is found to be consistent with the attainment of a stress intensification close to the tip such that the maximum principal stress a,, exceeds a, over a characteristic distance, determined as twice the grain size. The model is seen to predict the experimentally determined variation of K,, with temperature over the range -150 to -75°C from a knowledge of the yield stress and hardening properties. It is further shown that the onset of fibrous fracture ahead of the tip can be deduced from the position of the maximum achievable stress intensiiication. The relationship between the model for fracture ahead of a sharp crack, and that ahead of a rounded notch, is discussed in detail.

Benefits of Modest Weight Loss in Improving Cardiovascular Risk Factors in Overweight and Obese Individuals With Type 2 Diabetes

Abstract: OBJECTIVE Overweight and obese individuals are encouraged to lose 5–10% of their body weight to improve cardiovascular disease (CVD) risk, but data supporting this recommendation are limited, particularly for individuals with type 2 diabetes. RESEARCH DESIGN AND METHODS We conducted an observational analysis of participants in the Look AHEAD (Action For Health in Diabetes) study ( n = 5,145, 40.5% male, 37% from ethnic/racial minorities) and examined the association between the magnitude of weight loss and changes in CVD risk factors at 1 year and the odds of meeting predefined criteria for clinically significant improvements in risk factors in individuals with type 2 diabetes. RESULTS The magnitude of weight loss at 1 year was strongly ( P P = 0.79). Compared with weight-stable participants, those who lost 5 to 1c (odds ratio 3.52 [95% CI 2.81–4.40]), a 5-mmHg decrease in diastolic blood pressure (1.48 [1.20–1.82]), a 5-mmHg decrease in systolic blood pressure (1.56 [1.27–1.91]), a 5 mg/dL increase in HDL cholesterol (1.69 [1.37–2.07]), and a 40 mg/dL decrease in triglycerides (2.20 [1.71–2.83]). The odds of clinically significant improvements in most risk factors were even greater in those who lost 10–15% of their body weight. CONCLUSIONS Modest weight losses of 5 to

Silicon-based Nanomaterials for Lithium-Ion Batteries - A Review

Abstract: There are growing concerns over the environmental, climate, and health impacts caused by using non-renewable fossil fuels. The utilization of green energy, including solar and wind power, is believed to be one of the most promising alternatives to support more sustainable economic growth. In this regard, lithium-ion batteries (LIBs) can play a critically important role. To further increase the energy and power densities of LIBs, silicon anodes have been intensively explored due to their high capacity, low operation potential, environmental friendliness, and high abundance. The main challenges for the practical implementation of silicon anodes, however, are the huge volume variation during lithiation and delithiation processes and the unstable solid-electrolyte interphase (SEI) films. Recently, significant breakthroughs have been achieved utilizing advanced nanotechnologies in terms of increasing cycle life and enhancing charging rate performance due partially to the excellent mechanical properties of nanomaterials, high surface area, and fast lithium and electron transportation. Here, the most recent advance in the applications of 0D (nanoparticles), 1D (nanowires and nanotubes), and 2D (thin film) silicon nanomaterials in LIBs are summarized. The synthetic routes and electrochemical performance of these Si nanomaterials, and the underlying reaction mechanisms are systematically described.

Analysis of shared heritability in common disorders of the brain

Abstract: Disorders of the brain can exhibit considerable epidemiological comorbidity and often share symptoms, provoking debate about their etiologic overlap. We quantified the genetic sharing of 25 brain disorders from genome-wide association studies of 265,218 patients and 784,643 control participants and assessed their relationship to 17 phenotypes from 1,191,588 individuals. Psychiatric disorders share common variant risk, whereas neurological disorders appear more distinct from one another and from the psychiatric disorders. We also identified significant sharing between disorders and a number of brain phenotypes, including cognitive measures. Further, we conducted simulations to explore how statistical power, diagnostic misclassification, and phenotypic heterogeneity affect genetic correlations. These results highlight the importance of common genetic variation as a risk factor for brain disorders and the value of heritability-based methods in understanding their etiology.