Non-isothermal Mold Filling and Curing Simulation in Thin Cavities with Preplaced Fiber Mats

A numerical model for non-isothermal mold filling and curing simulation in thin cavities with preplaced fiber mats was developed based on the control volume method. Both lumped temperature system (i.e. local thermal equilibrium between the resin and the fiber) and unlumped temperature system (i.e. thermal non-equilibrium locally) were considered. A Lagrangian coordinate system was used in the flow front region to improve the energy transfer calculation. Several molding simulation results were presented to show the effect of fiber mat presence (in the mold cavity) on the inlet pressure and temperaturedistribution.

The diagnostic value of white cell count, C-reactive protein and bilirubin in acute appendicitis and its complications

INTRODUCTION

Inflammatory markers such as white cell count (WCC) and C-reactive protein (CRP) and, more recently, bilirubin have been used as adjuncts in the diagnosis of appendicitis. The aim of this study was to determine the diagnostic accuracy of the above markers in acute and perforated appendicitis as well as their value in excluding the condition.

METHODS

A retrospective analysis of 1,169 appendicectomies was performed. Patients were grouped according to histological examination of appendicectomy specimens (normal appendix = NA, acute appendicitis = AA, perforated appendicitis = PA) and preoperative laboratory test results were correlated. Receiver operating characteristic (ROC) curve area analysis (area under the curve [AUC]) was performed to examine diagnostic accuracy.

RESULTS

ROC analysis of all laboratory variables showed that no independent variable was diagnostic for AA. Good diagnostic accuracy was seen for AA when all variables were combined (WCC/CRP/bilirubin combined AUC: 0.8173). In PA, the median CRP level was significantly higher than that of AA (158mg/l vs 30mg, p<0.0001). CRP also showed the highest sensitivity (100%) and negative predictive value (100%) for PA. CRP had the highest diagnostic accuracy in PA (AUC: 0.9322) and this was increased when it was combined with WCC (AUC: 0.9388). Bilirubin added no diagnostic value in PA. Normal levels of WCC, CRP and bilirubin could not rule out appendicitis.

CONCLUSIONS

CRP provides the highest diagnostic accuracy for PA. Bilirubin did not provide any discriminatory value for AA and its complications. Normal inflammatory markers cannot exclude appendicitis, which remains a clinical diagnosis.

Development of new photon-counting detectors for single-molecule fluorescence microscopy

Two optical configurations are commonly used in single-molecule fluorescence microscopy: point-like excitation and detection to study freely diffusing molecules, and wide field illumination and detection to study surface immobilized or slowly diffusing molecules. Both approaches have common features, but also differ in significant aspects. In particular, they use different detectors, which share some requirements but also have major technical differences. Currently, two types of detectors best fulfil the needs of each approach: single-photon-counting avalanche diodes (SPADs) for point-like detection, and electron-multiplying charge-coupled devices (EMCCDs) for wide field detection. However, there is room for improvements in both cases. The first configuration suffers from low throughput owing to the analysis of data from a single location. The second, on the other hand, is limited to relatively low frame rates and loses the benefit of single-photon-counting approaches. During the past few years, new developments in point-like and wide field detectors have started addressing some of these issues. Here, we describe our recent progresses towards increasing the throughput of single-molecule fluorescence spectroscopy in solution using parallel arrays of SPADs. We also discuss our development of large area photon-counting cameras achieving subnanosecond resolution for fluorescence lifetime imaging applications at the single-molecule level.

Past, present, and future of endovascular stroke therapies

Endovascular therapy in the acute management of ischemic stroke has become more common with technologic advances, such as easier navigation into the intracranial circulation and improved treatment efficacy with the advent of revascularization devices. This select review outlines milestones in the application of endovascular therapy in acute ischemic stroke (AIS) and offers some insight into important factors influencing the future directions of endovascular AIS treatment. In particular, we discuss the evolution of endovascular devices for AIS and how ingenuity continues to offer novel treatments. With these advances, the future of endovascular AIS treatment is promising.

Ages at different reproductive events, numbers of menstrual cycles in between and breast cancer risk

One hundred and seventy-five pathologically confirmed new cases of female breast cancer in National Taiwan University Hospital were selected as the case group. Four hundred and fifty-seven inpatient controls were individually matched for each case by age and date of admission. Information of reproductive factors and potential confounders were collected from questionnaire interview and medical records. Menstrual cycles before and after first fuIl-term pregnancy were estimated from the questionnaire. Conditional logistic regression was used to estimate the effects of reproductive risk factors and numbers of menstrual cycles before and after first full-term pregnancy. After adjusting for educational level, body mass index, family history of breast cancer and oral contraceptive use, age at menarche and menopause only showed borderline significance. Age at first full-term birth predicted breast cancer risk better. Parity was the most important protective factor. Number of menstrual cycles before first full-term pregnancy was also positively associated with breast cancer risk with linear trends.

Accuracy of noninvasive quantification of brain NAA concentrations using PRESS sequence: verification in a swine model with external standard

The metabolite ratios had been employed in the field of MR spectroscopy (MRS) for a long period. The main drawback of metabolite ratio is that ratio results are not comparable with absolute metabolite concentration in vivo. The purpose of this study was to examine the accuracy of noninvasive quantification of brain N-acetylaspartate (NAA) concentrations using previously reported MR external standard method. Eight swine were scanned on a GE 1.5 T scanner with a standard head coil. The external standard method was utilized with a sphere filled with NAA, GABA, glutamine, glutamate, creatine, choline chloride, and myo-inositol. The position resolved spectroscopy (PRESS) sequence was used with TE=135 msec, TR=1500 msec, and 128 scan averages. The analysis of MRS was done with SAGE/IDL program. In vivo NAA concentration was obtained using the equation S=N * e(-TE/T₂) * [1-e(-TR/T₁). In vitro NAA concentration was measured by high performance liquid chromatography (HPLC). In the MRS group, the mean concentration of NAA was 10.03 plusmn 0.74 mmol/kg. In the HPLC group, the mean concentration of NAA was 9.22 plusmn 0.55 mmol/kg. There was no significant difference between the two groups (p = 0.46). However, slightly higher value was observed in the MRS group (7/8 swine), compared with HPLC group. The range of differences was between 0.02~2.05 mmol/kg. MRS external reference method could be more accurate than internal reference method. ¹H MRS does not distinguish between N-acetyl resonance frequencies and other N-acetylated amino acids.

Tuning the performance of organic spintronic devices using x-ray generated traps

X rays produced during electron-beam deposition of metallic electrodes drastically change the performance of organic spintronic devices. The x rays generate traps with an activation energy of ≈0.5  eV in a commonly used organic. These traps lead to a dramatic decrease in spin-diffusion length in organic spin valves. In organic magnetoresistive (OMAR) devices, however, the traps strongly enhance magnetoresistance. OMAR is an intrinsic magnetotransport phenomenon and does not rely on spin injection. We discuss our observations in the framework of currently existing theories.

Involvement of fatty acid metabolism in the hepatotoxicity induced by divalproex sodium

Divalproex sodium is an antiepileptic drug. Hepatotoxicity is one of the most common side effects induced by divalproex sodium. Impaired fatty acid metabolism is considered to play an important role in the drug-induced hepatotoxicity. The sterol regulatory element-binding protein 1c (SREBP-1c) and peroxisome proliferator-activated receptor α (PPARα) are two key transcription factors involved, respectively, in fatty acid synthesis and degradation in liver. In the present study, we investigated the hepatotoxicity induced by divalproex sodium and its potential mechanism. The results indicated that divalproex sodium significantly decreased the cell viability and increased lactate dehydrogenase leakage in hepatocytes. The activities of alanine aminotransferase and aspartate transaminase were increased in hepatocytes treated with divalproex sodium. Furthermore, divalproex sodium activated SREBP-1c and increased the mRNA expressions of acetyl-CoA carboxylase 1, fatty acid synthase and stearoyl-CoA desaturase 1. Divalproex sodium also inhibited PPARα and decreased the messenger RNA expressions of 3-hydroxy-3-methylglutaryl-CoA synthase 2 and carnitine palmitoyltransferase 1A. These results suggest that the hepatotoxicity induced by divalproex sodium may be related with fatty acid synthesis and degradation mediated by SREBP-1c and PPARα in hepatocytes.

Are existing measures of overall diet quality associated with peak bone mass in young premenopausal women?

BACKGROUND

  Low peak bone mass in young adulthood is associated with an increased risk of osteoporosis and fracture after menopause, and an understanding of the modifiable factors that contribute to low peak bone mass is important for fracture prevention. Diet is an important modifiable factor linked to bone health and, although studies have examined the role of individual dietary components in bone health, bone growth and maintenance are complex processes, and such studies may not adequately represent the role of diet in these processes.

METHODS

  To address this issue, a cross-sectional analysis of 226 healthy, premenopausal women aged 18-30 years was conducted to determine whether existing indices of overall diet quality are associated with bone density in premenopausal women nearing peak bone mass. Bone density was measured using dual-energy X-ray absorptiometry and diet quality was measured using two overall diet scores based on current dietary guidelines: the Recommended Food Score and the Alternate Healthy Eating Index (AHEI).

RESULTS

  In the multiple linear regression, bone density did not increase across quartiles of either diet quality score and was not associated with continuous diet quality variables. Furthermore, none of the individual AHEI components (e.g. fruit intake, vegetable intake) were associated with bone density.

CONCLUSIONS

  These findings suggest that existing diet quality scores are not appropriate for studies of peak bone mass, most likely because they do not give sufficient weight to foods and nutrients important to bone health. We recommend the development of a diet pattern index that better predicts bone mass measures.

Parallel multispot smFRET analysis using an 8-pixel SPAD array

Single-molecule Förster resonance energy transfer (smFRET) is a powerful tool for extracting distance information between two fluorophores (a donor and acceptor dye) on a nanometer scale. This method is commonly used to monitor binding interactions or intra- and intermolecular conformations in biomolecules freely diffusing through a focal volume or immobilized on a surface. The diffusing geometry has the advantage to not interfere with the molecules and to give access to fast time scales. However, separating photon bursts from individual molecules requires low sample concentrations. This results in long acquisition time (several minutes to an hour) to obtain sufficient statistics. It also prevents studying dynamic phenomena happening on time scales larger than the burst duration and smaller than the acquisition time. Parallelization of acquisition overcomes this limit by increasing the acquisition rate using the same low concentrations required for individual molecule burst identification. In this work we present a new two-color smFRET approach using multispot excitation and detection. The donor excitation pattern is composed of 4 spots arranged in a linear pattern. The fluorescent emission of donor and acceptor dyes is then collected and refocused on two separate areas of a custom 8-pixel SPAD array. We report smFRET measurements performed on various DNA samples synthesized with various distances between the donor and acceptor fluorophores. We demonstrate that our approach provides identical FRET efficiency values to a conventional single-spot acquisition approach, but with a reduced acquisition time. Our work thus opens the way to high-throughput smFRET analysis on freely diffusing molecules.

Fast and direct measurements of the electrical properties of graphene using micro four-point probes

We present measurements of the electronic properties of graphene using a repositionable micro four-point probe system, which we show here to have unique advantages over measurements made on lithographically defined devices; namely speed, simplicity and lack of a need to pattern graphene. Measurements are performed in ambient, vacuum and controlled environmental conditions using an environmental scanning electron microscope (SEM). The results are comparable to previous results for microcleaved graphene on silicon dioxide (SiO(2)). We observe a pronounced hysteresis of the charge neutrality point, dependent on the sweep rate of the gate voltage; and environmental measurements provide insight into the sensor application prospects of graphene. The method offers a fast, local and non-destructive technique for electronic measurements on graphene, which can be positioned freely on a graphene flake.

A randomized trial of punctuated antiretroviral therapy in Ugandan HIV-seropositive adults with pulmonary tuberculosis and CD4⁺ T-cell counts of ≥ 350 cells/μL

BACKGROUND

Optimal treatment of human immunodeficiency virus (HIV)-associated tuberculosis in patients with high CD4⁺ T-cell counts is unknown. Suppression of viral replication during therapy for tuberculosis may block effects of immune activation on T cells and slow HIV disease progression.

METHODS

We conducted a randomized trial in 214 HIV-infected patients with active tuberculosis and CD4⁺ T-cell counts of ≥ 350 cells/μL to determine whether 6 months of antiretroviral therapy given during tuberculosis treatment would improve clinical outcomes. Subjects were randomized to receive 6 months of abacavir-lamivudine-zidovudine concurrent with tuberculosis therapy or delayed antiretroviral therapy. Endpoints were CD4⁺ T-cell counts of < 250 cells/μL, AIDS, or death.

RESULTS

Intervention and comparison arms had similar median CD4⁺ counts (517 and 534 cells/μL, respectively) and HIV RNA levels (4.6 and 4.7 log₁₀ copies/μL, respectively). Viral suppression was achieved in 86% of patients allocated to intervention. Seventeen subjects (15.6%) in the intervention arm developed study outcome compared to 25 subjects (22.8%) in the comparison arm (P = .17). Grade 3 or 4 adverse events were less frequent in the intervention arm. By 2 months, 90% of subjects in both arms were culture-negative for tuberculosis.

CONCLUSIONS

Short-term antiretroviral therapy during tuberculosis treatment in patients with CD4⁺T-cell counts of >350 cells/μL was safe and associated with clinical benefits.