Publications

Prenucleation Clusters

'Prenucleation Clusters' published in 'Encyclopedia of Nanotechnology'

Organic Surface Chemistry: Polymers and Self-Assembled Monolayers

Friction between van der Waals Solids during Lattice Directed Sliding

Nanometer-scale crystals of the two-dimensional oxide molybdenum trioxide (MoO3) were formed atop the transition metal dichalcogenides MoS2 and MoSe2. The MoO3 nanocrystals are partially commensurate with the dichalcogenide substrates, being aligned only along one of the substrate's crystallographic axes. These nanocrystals can be slid only along the aligned direction and maintain their alignment with the substrate during motion. Using an AFM probe to oscillate the nanocrystals, it was found that the lateral force required to move them increased linearly with nanocrystal area. The slope of this curve, the interfacial shear strength, was significantly lower than for macroscale systems. It also depended strongly on the duration and the velocity of sliding of the crystal, suggesting a thermal activation model for the system. Finally, it was found that lower commensuration between the nanocrystal and the substrate increased the interfacial shear, a trend opposite that predicted theoretically.

On the determination of elastodynamic crack tip stress fields

A linear elastic body in plane strain which contains a stationary crack and which is initially at rest and stress free is considered. It is shown that if the elastodynamic displacement field and stress intensity factor are known, as functions of crack length, for any symmetrical distribution of time-varying forces which acts on the body, subsequent to t=0, then the stress intensity factor due to any other symmetrical load system whatsoever which acts on the same body may be directly determined. The other load system may be of arbitrary spatial distribution and time variation. Further, that part of the elastodynamic displacement field due to the other load system, which arises from the presence of the crack, may also be directly determined. The results are obtained by extension of Rice's mode of derivation of the corresponding Bueckner-Rice elastostatic results to Laplace-transformed elastodynamic variables. Likewise, the existence of a universal elastodynamic “weight function” for any given cracked body is demonstrated. As an application, Freund's recent result for the stress intensity factor due to suddenly applied concentrated forces on the crack surfaces is derived directly by our method, from de Hoop's earlier solution for suddenly applied uniform pressures.

Parallel (‖) ELLPACK: an expert system for parallel processing of partial differential equations

We are developing an expert system environment for solving elliptic partial differential equations (PDEs) defined on two and three dimensional domains on MIMD type parallel machines. According to its design objectives, it will provide a uniform programming environment for implementing parallel MIMD PDE solution solvers, an automatic partitioning and allocation of the PDE computation, a very high level problem specification language, an interactive high level environment for grid selection, a domain partitioning and mapping facility, a uniform environment for obtaining software engineering measurements and a graphical display of solution output. The ‖ELLPACK is implemented on a hardware facility consisting of a graphics workstation supporting X11 window system and connected to NCUBE and SEQUENT machines through a wide bandwidth local network. The software infrastructure includes (i) a PDE problem oriented language processor, (ii) a geometry processing tool which is capable of generating fixed meshes and domain decompositions automatically and interactively, (iii) an algorithm mapper facility for partitioning and mapping the underlying PDE computation and (iv) an expert front end that selects the discretization mesh, the parallel algorithm⧸machine pair and its configuration. In order to support the solution of elliptic PDEs on fixed meshes, we are building a library of finite difference and element discretization methods and direct⧸iterative solvers for the NCUBE and SEQUENT machines.

Multistability of segmented rings by programming natural curvature

Multistable structures have widespread applications in the design of deployable aerospace systems, mechanical metamaterials, flexible electronics, and multimodal soft robotics due to their capability of shape reconfiguration between multiple stable states. Recently, the snap-folding of rings, often in the form of circles or polygons, has shown the capability of inducing diverse stable configurations. The natural curvature of the rod segment (curvature in its stress-free state) plays an important role in the elastic stability of these rings, determining the number and form of their stable configurations during folding. Here, we develop a general theoretical framework for the elastic stability analysis of segmented rings (e.g., polygons) based on an energy variational approach. Combining this framework with finite element simulations, we map out all planar stable configurations of various segmented rings and determine the natural curvature ranges of their multistable states. The theoretical and numerical results are validated through experiments, which demonstrate that a segmented ring with a rectangular cross-section can show up to six distinct planar stable states. The results also reveal that, by rationally designing the segment number and natural curvature of the segmented ring, its one- or multiloop configuration can store more strain energy than a circular ring of the same total length. We envision that the proposed strategy for achieving multistability in the current work will aid in the design of multifunctional, reconfigurable, and deployable structures.

Nut and Peanut Butter Consumption and Risk of Type 2 Diabetes in Women

Obstetrical & Gynecological Survey 58(4):p 258-259, April 2003. | DOI: 10.1097/01.OGX.0000058685.18516.86

ChemInform Abstract: INTERMEDIAERE RADIKALE BEI DER RK. VON NEOPHYLLITHIUM MIT SAUERSTOFF

Abstract Aus der Bildung von tert.‐Butylbenzol sowie 1,1‐Dimethyl‐ und 2,2‐Dimethyl‐ 2‐phenyl‐äthanol bei der Oxidation von Neophyllithium in n‐Pentan und n‐Hep tan (nicht in Gegenwart von z.B. Tetrahydrofuran) wird auf die intermediäre Bildung von Neophylradikalen geschlossen.

[Dongfeng-Tongji cohort: methodology of the survey and the characteristics of baseline and initial population of follow-up program].

The DFTJ cohort study offered us an opportunity to explore the effects of environmental, genetic, as well as their interactions with major chronic diseases in a Chinese occupational population.

910 A systematic review and meta-analysis of candidate gene association studies of lower urinary tract symptoms in men

Sex Differences of Infant and Child Mortality in China

The purpose of this paper was to study the sex differences in infant mortality and mortality before the age of 5 in China, and the differences between urban and rural areas on the one hand and urban areas of mainland China and Hong Kong on the other. Published data from the 1982 and 1990 national censuses, the mortality survey of 1976, and UN's publications were used to calculate sex differences and sex ratios of mortality. Infant mortality of both sexes decreased notably from the 1970's onwards, the sex ratios of mortality being 1.15 in 1973–75, 1.06 in 1981 and 0.86 in 1990. A remarkable decline of mortality before the age of 5 was also seen in both sexes, but the sex ratios of mortality were not greatly altered, remaining less than 1 from the 1970's on. In rural areas female infants and young children had a higher mortality compared with males than in urban areas. In Hong Kong, the sex differences of infant and early child mortality were much smaller than in urban areas of mainland China.

Does CRP Play a Causal Role in the Development of Coronary Heart Disease: Results of a Mendelian Randomisation Experiment Involving 128,935 People

Background: C-reactive protein (CRP) is associated with risk of coronary heart disease (CHD). Whether CRP is causally associated with CHD or merely a marker of underlying atherosclerosis is uncerta...

Sedentary lifestyle and risk of obesity and type 2 diabetes

Abstract Obesity and type 2 diabetes have reached epidemic proportions in the United States. It is well‐established that increasing physical activity plays an important role in reducing rick of obesity and diabetes. Few studies, however, have examined the association between sedentary behaviors such as prolonged television (TV) watching and obesity and diabetes. Using data from a large prospective cohort study, the Health Professionals’ Follow‐up Study, we have demonstrated that increasing TV watching is strongly associated with obesity and weight gain, independent of diet and exercise. Also, prolonged TV watching is associated with a significantly increased risk of type 2 diabetes. Men who watched TV more than 40 h per week had a nearly threefold increase in the risk of type 2 diabetes compared with those who spent less than 1 h per week watching TV. The increased risk was not entirely explained by the decreased physical activity and unhealthy eating patterns associated with TV watching. Thus, public health campaigns to reduce the risk of obesity and type 2 diabetes should promote not only increasing exercise levels but also decreasing sedentary behaviors, especially prolonged TV watching.

Tricarboxylic acid cycle related-metabolites and risk of atrial fibrillation and heart failure

Nanowire Photonic Circuit Elements

No abstract is provided for this article.

Diet-Quality Scores and the Risk of Type 2 Diabetes in Men

OBJECTIVE To 1) compare associations of diet-quality scores, which were inversely associated with cardiovascular disease, with incident type 2 diabetes and 2) test for differences in absolute-risk reduction across various strata. RESEARCH DESIGN AND METHODS Men from the Health Professionals Follow-Up Study, who were initially free of type 2 diabetes, cardiovascular disease, or cancer (n = 41,615), were followed for ≤20 years. The Healthy Eating Index (HEI) 2005, the alternative HEI (aHEI) the Recommended Food Score, the alternative Mediterranean Diet (aMED) Score, and the Dietary Approaches to Stop Hypertension (DASH) Score were calculated from food-frequency questionnaires. Cox proportional hazard models with time-varying covariates were used to assess risk by quintiles and continuous intervals. RESULTS There were 2,795 incident cases of type 2 diabetes. After multivariate adjustment, the aHEI, aMED, and DASH scores were significantly associated with reduced risk. A 1-SD increase was associated with 9–13% reduced risk (P < 0.01), and the DASH score was associated with lower risk independent of other scores. These scores were associated with lower absolute risk among those who were overweight or obese compared with normal weight (P for interaction < 0.01). CONCLUSIONS Several diet-quality scores were associated with a lower risk of type 2 diabetes and reflect a common dietary pattern characterized by high intakes of plant-based foods such as whole grains; moderate alcohol; and low intakes of red and processed meat, sodium, sugar-sweetened beverages, and trans fat. High-quality diets may yield the greatest reduction in diabetes cases when followed by those with a high BMI.

Abstract 030: Dietary Inflammatory Potential is Associated with Cardiovascular Disease Risk in Two Large Prospective Cohort Studies of US Men and Women

Introduction: Chronic inflammation plays a pathogenic role in cardiovascular disease (CVD) development. Dietary factors have been implicated in CVD etiology and may have an impact on chronic inflammation. Hypothesis: Proinflammatory diets are associated with higher CVD risk. Methods: We include74,544 women in the Nurses’ Health Study (from 1984 through 2012) and 43,904 men in the Health Professionals Follow-up Study (from 1986 through 2012), who were free of heart disease, stroke, and cancer at baseline. Dietary inflammatory potentials were assessed using an empirical dietary inflammatory pattern (EDIP) score that has been pre-defined by 18 food components based on their associations with circulating levels of systemic inflammation markers C-reactive protein, interleukin-6, and tumor necrosis factor-α receptor 2. Adjusted hazard ratios (HRs) and 95% confidence internals (CIs) for CVD were calculated using Cox regressions. Results: During 2,831,128 person-years of follow-up, we documented 13,249 incident CVD cases, including 8,178 coronary heart disease cases and 5,182 stroke cases. After adjusting for established risk factors and potential confounders including body-mass index and aspirin or other nonsteroidal anti-inflammatory medication use, a higher EDIP score was associated with an increased risk of CVD (in pooled analyses, HR [95% CI] comparing the highest to the lowest quintiles were 1.29 [1.22 to 1.37]; P trend <0.001), CHD (HR = 1.32[1.23 to 1.42]; P trend <0.001), and stroke (HR = 1.25 [1.14 to 1.37]; P trend <0.001). Associations were similar among subgroups of participants, including by age, sex, family history, BMI, physical activity, and alcohol intake; but were stronger among non/past-smoking than current smoking women ( P interaction <0.002). Conclusions: Findings from two large US prospective cohort studies suggest that inflammation may be a potential mechanism linking dietary patterns to CVD progression. Reducing the proinflammatory potentials of the diet may assist CVD prevention.

Injectable ventral spinal stimulator evokes programmable and biomimetic hindlimb motion

Spinal cord neuromodulation can restore partial to complete loss of motor functions associated with neuromotor disease and trauma. Current technologies have made substantial progress, but have limitations as dorsal epidural or intraspinal devices that are either remote to ventral motor neurons or subject to surgical intervention in the spinal tissue. Here, we describe a flexible and stretchable spinal stimulator design with nanoscale thickness that can be implanted by minimally-invasive injection through a polymeric catheter to target the ventral spinal space of mice. Ventrolaterally implanted devices exhibited substantially lower stimulation threshold currents and more precise recruitment of motor pools than comparable dorsal epidural implants. Functionally relevant and novel hindlimb movements were achieved via specific stimulation patterns of the electrodes. This approach holds translational potential for improving controllable limb function following spinal cord injury or neuromotor disease.