Optimal design and quantum limit for second harmonic generation in semiconductor heterostructures

The optimal design for infrared second harmonic generation (SHG) is determined for a GaAs-based quantum device using a recently developed genetic approach. Both compositional parameters and electric field are simultaneously optimized, and the quantum limit for SHG, set by the trade-off between large dipole moments (favouring electron delocalization) and large overlaps (favouring electron localization), is determined. Optimal devices are generally obtained with an asymmetric double quantum well shape with narrow barriers and a graded region sideways to the largest well. An electric field is not found to lead to improved SHG if compositional parameters are optimized.Comment: 5 pages, 2 figures embedded. To apper in J. App. Phys. (Jan 2nd, 2001

Factors affecting ventilation effectiveness in SARS wards

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Pharmacokinetic and pharmacodynamic evaluation of a new sustained-release capsules using starch-sponge matrix (SSM) release system for nifedipine in rats

We conducted a performance assessment study for a new sustained-release capsule including starch-sponge matrix (SSM). The SSM, which is a support medium for drug release, was made from 2.5% cornstarch glue by means of freezing dry method. The SSM capsule was applied for nifedipine (NFP), a calcium channel blocker, and evaluated pharmacokinetic and pharmacodynamic (PK/PD) profiles of NFP after intraduodenal administration of SSM capsules including 2.5 or 5.0 mg of NFP per capsule to rats. Plasma NFP concentrations from the SSM capsules showed dose-dependent increases with a Michaelis-Menten like behavior over 360 minutes after intraduodenal administration. The values of area under the concentration vs. time curve from time zero to 360 min (AUC0-360) of NFP declined in making SSM capsules as compared to control capsules due to a simple physical mixture of NFP and cornstarch, but the values of mean residence time (MRT0-360) extended and abidingness of SSM capsules were admitted with dose-dependent manner. As for a PD parameter, the mean arterial blood pressure (mABP) derived from the SSM capsules showed 15~20% decrease of baseline within 120min after intraduodenal administration, and thereafter the mABP in 2.5 mg SSM capsule was gradually recovered, while a relatively smooth and even change was found in the mABP at 5.0 mg SSM capsule. The relationships between plasma NFP concentration and sampling-time corresponding mABP after intraduodenal administration of SSM capsules showed no rapid change in the mABP, indicating that a sustained-release mechanism due to the SSM functions sufficiently to avoid a fluctuating blood pressure accompanied by going up and down of plasma levels of NFP. The SSM capsules exhibited a sustained-release pharmacokinetics of NFP, and made the fluctuation range with blood pressure small compared to the physical mixture preparations. Thus, it was evidenced that the SSM capsule is useful device to provide a sustained-release systems and optimal therapeutic efficacy of drugs.Keywords: Controlled-release, Cornstarch, Matrix, Nifedipine, Pharmacokinetics, Pharmacodynamics

Consumption of dried fruit of Crataegus pinnatifida (hawthorn) suppresses high-cholesterol diet-induced hypercholesterolemia in rats

Author name used in this publication: Mabel Yin-Chun YauAuthor name used in this publication: Peter Hoi-Fu Yu2009-2010 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe

2011-2012 Master Class - Elmar Oliveira (Violin)

https://spiral.lynn.edu/conservatory_masterclasses/1062/thumbnail.jp

Use of liver stiffness measurement for liver resection surgery: correlation with indocyanine green clearance testing and post-operative outcome

Background:Liver stiffness measurement (LSM) using transient elastography has recently become available for the assessment of liver fibrosis. Whether LSM can predict the functional liver reserve in patients undergoing liver resection is not certain.Aim:To correlate liver stiffness measurement (LSM) with indocyanine green (ICG) clearance test and liver biochemistry, and to determine its usefulness in predicting postoperative outcomes in patients undergoing liver resection.Patients and Methods:Transient elastography and ICG clearance test were performed pre-operatively in 44 patients with hepatocellular carcinoma. The LSM and ICG retention rate at 15 minutes (R15) were correlated with pre-operative factors and post-operative outcomes.Results:There was significant correlation between ICG R15 and LSM. In patients with LSM ≥11 kPa vs <11 kPa, there was significantly higher ICG R15 (17.1% vs 10.0% respectively, p = 0.025). For patients with ICG R15≥10% compared to those <10%, there was significantly higher LSM (12.0 vs 7.6 kPa respectively, p = 0.015). Twenty-eight patients proceeded to resection. There was a significant correlation between LSM and the peak INR after liver resection (r = 0.426, p = 0.024). There was a significant correlation between ICG R15 and the post-operative peak AST level (r = -0.414, p = 0.029) and peak ALT level (r = -0.568, p = 0.002). The operative time was a significant independent factor associated with post-operative complications and peak INR.Conclusion:LSM correlated well with ICG R15 in patients undergoing liver resection, and predicted early post-operative complications. Addition of LSM to ICG R15 testing may provide better prognostic information for patients undergoing resection. © 2013 Fung et al.published_or_final_versio

Quantification of Influenza Virus RNA in Aerosols in Patient Rooms

The potential for human influenza viruses to spread through fine particle aerosols remains controversial. The objective of our study was to determine whether influenza viruses could be detected in fine particles in hospital rooms. METHODS AND FINDINGS: We sampled the air in 2-bed patient isolation rooms for four hours, placing cyclone samplers at heights of 1.5m and 1.0m. We collected ten air samples each in the presence of at least one patient with confirmed influenza A virus infection, and tested the samples by reverse transcription polymerase chain reaction. We recovered influenza A virus RNA from 5/10 collections (50%); 4/5 were from particles>4 μm, 1/5 from 1-4 μm, and none in particles<1 μm. CONCLUSIONS: Detection of influenza virus RNA in aerosols at low concentrations in patient rooms suggests that healthcare workers and visitors might have frequent exposure to airborne influenza virus in proximity to infected patients. A limitation of our study was the small sample size. Further studies should be done to quantify the concentration of viable influenza virus in healthcare settings, and factors affecting the detection of influenza viruses in fine particles in the air.published_or_final_versio

ABO(H) blood group A and B glycosyltransferases recognize substrate via specific conformational changes.

The final step in the enzymatic synthesis of the ABO(H) blood group A and B antigens is catalyzed by two closely related glycosyltransferases, an alpha-(1-->3)-N-acetylgalactosaminyltransferase (GTA) and an alpha-(1-->3)-galactosyltransferase (GTB). Of their 354 amino acid residues, GTA and GTB differ by only four "critical" residues. High resolution structures for GTB and the GTA/GTB chimeric enzymes GTB/G176R and GTB/G176R/G235S bound to a panel of donor and acceptor analog substrates reveal "open," "semi-closed," and "closed" conformations as the enzymes go from the unliganded to the liganded states. In the open form the internal polypeptide loop (amino acid residues 177-195) adjacent to the active site in the unliganded or H antigen-bound enzymes is composed of two alpha-helices spanning Arg(180)-Met(186) and Arg(188)-Asp(194), respectively. The semi-closed and closed forms of the enzymes are generated by binding of UDP or of UDP and H antigen analogs, respectively, and show that these helices merge to form a single distorted helical structure with alternating alpha-3(10)-alpha character that partially occludes the active site. The closed form is distinguished from the semi-closed form by the ordering of the final nine C-terminal residues through the formation of hydrogen bonds to both UDP and H antigen analogs. The semi-closed forms for various mutants generally show significantly more disorder than the open forms, whereas the closed forms display little or no disorder depending strongly on the identity of residue 176. Finally, the use of synthetic analogs reveals how H antigen acceptor binding can be critical in stabilizing the closed conformation. These structures demonstrate a delicately balanced substrate recognition mechanism and give insight on critical aspects of donor and acceptor specificity, on the order of substrate binding, and on the requirements for catalysis

Synergistic drug combinations from electronic health records and gene expression.

ObjectiveUsing electronic health records (EHRs) and biomolecular data, we sought to discover drug pairs with synergistic repurposing potential. EHRs provide real-world treatment and outcome patterns, while complementary biomolecular data, including disease-specific gene expression and drug-protein interactions, provide mechanistic understanding.MethodWe applied Group Lasso INTERaction NETwork (glinternet), an overlap group lasso penalty on a logistic regression model, with pairwise interactions to identify variables and interacting drug pairs associated with reduced 5-year mortality using EHRs of 9945 breast cancer patients. We identified differentially expressed genes from 14 case-control human breast cancer gene expression datasets and integrated them with drug-protein networks. Drugs in the network were scored according to their association with breast cancer individually or in pairs. Lastly, we determined whether synergistic drug pairs found in the EHRs were enriched among synergistic drug pairs from gene-expression data using a method similar to gene set enrichment analysis.ResultsFrom EHRs, we discovered 3 drug-class pairs associated with lower mortality: anti-inflammatories and hormone antagonists, anti-inflammatories and lipid modifiers, and lipid modifiers and obstructive airway drugs. The first 2 pairs were also enriched among pairs discovered using gene expression data and are supported by molecular interactions in drug-protein networks and preclinical and epidemiologic evidence.ConclusionsThis is a proof-of-concept study demonstrating that a combination of complementary data sources, such as EHRs and gene expression, can corroborate discoveries and provide mechanistic insight into drug synergism for repurposing