Block copolymers as polymeric stabilizers in non‐aqueous emulsion polymerization

This review summarizes the background and recent advances of block copolymer stabilized oil‐in‐oil emulsions. For non‐polymerizable emulsions which have promising application possibilities for biomedical and cosmetic formulations, it is shown that tailor‐made block copolymers are by far the most efficient stabilizers with respect to low molecular weight surfactants. The characteristic features of oil‐in‐oil emulsions comprising one polymerizable phase are described. These types of non‐aqueous emulsions are of interest as nanoreactor systems for the polymerization of moisture‐sensitive monomers or catalysts. Furthermore they are the starting point of novel heterophase polymerization processes for the preparation of sterically stabilized polymer particles, as well as of ‘liquid‐filled polymeric materials’. The concept of oil‐in‐oil emulsions is finally extended to those systems where the two phases are polymerizable by distinct polymerization mechanisms. This approach could offer attractive possibilities for the development of special coatings with neither water nor solvent evaporation in their drying or curing step. Copyright © 2011 Society of Chemical Industry     

A Fast DC Current Breaker

A fast dc current breaker circuit is presented and analyzed. Relevant design and control parameters are also derived. Furthermore, logic control implementation and power circuit component protection are discussed. It is shown that a simple control strategy is best suited for static loads at predefined load current levels. Also theoretical results are compared with experimental results.     

A Raman study of CdSe and ZnSe nanostructures

Raman studies have been carried out on CdSe nanotubes and ZnSe nanorods produced by surfactant-assisted synthesis. The Raman spectrum of CdSe nanotubes shows modes at 207.5 and 198 cm-1; the former arises from the longitudinal optic phonon mode red-shifted with respect to the bulk mode because of phonon confinement, and the latter is the l = 1 surface phonon. Analysis based on the phonon confinement model demonstrates that the size of the nanoparticle responsible for the red-shift is about 4 nm, close to the estimate from the blue-shift of the photoluminescence. The Raman spectrum of ZnSe nanorods shows modes at 257 and 213 cm-1, assigned to longitudinal and transverse optic phonons, blue-shifted with respect to the bulk ZnSe modes because of compressive strain. The mode at 237 cm-1 is the surface phonon.     

Estimation of missing markers in human motion capture

Motion capture is a prevalent technique for capturing and analyzing human articulations. A common problem encountered in motion capture is that some marker positions are often missing due to occlusions or ambiguities. Most methods for completing missing markers may quickly become ineffective and produce unsatisfactory results when a significant portion of the markers are missing for extended periods of time. We propose a data-driven, piecewise linear modeling approach to missing marker estimation that is especially beneficial in this scenario. We model motion sequences of a training set with a hierarchy of low-dimensional local linear models characterized by the principal components. For a new sequence with missing markers, we use a pre-trained classifier to identify the most appropriate local linear model for each frame and then recover the missing markers by finding the least squares solutions based on the available marker positions and the principal components of the associated model. Our experimental results demonstrate that our method is efficient in recovering the full-body motion and is robust to heterogeneous motion data.     

Power quality of small rural industries

Successful and economical operation of small rural industries (e.g. grain, dairy, irrigation, pig, poultry, beef feedlots, etc.) is a fundamental objective of society. However, when the performance and life expectancy of industrial electronic and electrical equipment is significantly affected by power supply anomalies caused by polluting loads at an industrial site and by utility normal operational activities, the economic benefits of this technology are quickly eradicated. This work presents the results of a detailed power supply quality survey of 23 small rural industries sponsored by the Canadian Electrical Association and provides a knowledge base on rural power quality and the possible origins of power supply anomalies. The major power quality problems experienced at the various industrial sites are summarized. The results of the survey provide a basis for mitigating actions by the electric utilities and their rural industrial customers to design and operate their electrical systems to minimize the effects of power supply anomalies     

Interfacial reactions of Sn-Ag-Cu solders modified by minor Zn alloying addition

The near-ternary eutectic Sn-Ag-Cu alloys have been identified as leading Pb-free solder candidates to replace Pb-bearing solders in microelectronic applications. However, recent investigations on the processing behavior and solder joints reliability assessment have revealed several potential reliability risk factors associated with the alloy system. The formation of large Ag₃Sn plates in Sn-Ag-Cu joints, especially when solidified in a relatively slow cooling rate, is one issue of concern. The implications of large Ag₃Sn plates on solder joint performance and several methods to control them have been discussed in previous studies. The minor Zn addition was found to be effective in reducing the amount of undercooling required for tin solidification and thereby to suppress the formation of large Ag₃Sn plates. The Zn addition also caused the changes in the bulk microstructure as well as the interfacial reaction. In this paper, an in-depth characterization of the interfacial reaction of Zn-added Sn-Ag-Cu solders on Cu and Au/Ni(P) surface finishes is reported. The effects of a Zn addition on modification of the interfacial IMCs and their growth kinetics are also discussed.     

A high-risk method for studying psychosocial antecedents of chronic pain: The prospective investigation of herpes zoster.

Although patients with chronic pain (CP) are often psychologically distressed, it has been difficult to determine whether this distress is an antecedent of CP or whether it is caused by the experience of living with CP. This investigation aimed to develop a method that would allow individuals who are at risk for the development of CP to be studied before the pain has become chronic. Patients with acute herpes zoster (HZ) were assessed with demographic, medical, pain, and psychosocial measures. Pain was assessed in follow-up interviews at 6 wks and 3, 5, 8, and 12 mo after these initial assessments. There were no significant differences between Ss who developed short-term HZ pain and Ss who did not develop short-term pain for any of the measures at the initial assessment, except for 1 measure of pain intensity. Ss who developed HZ CP, however, had significantly greater pain intensity, higher state and trait anxiety, greater depression, lower life satisfaction, and greater disease conviction at the initial assessment than Ss who did not develop CP. In discriminant analyses, disease conviction, pain intensity, and state anxiety each made a unique contribution to discriminating Ss who did and did not develop CP. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The duration of viral suppression during protease inhibitor therapy for HIV-1 infection is predicted by plasma HIV-1 RNA at the nadir

OBJECTIVE: To determine markers that are associated with the durability of virologic response to therapy with HIV protease inhibitors in HIV-infected individuals. DESIGN: This study encompassed two retrospective analyses of the duration of virologic response to protease inhibitor therapy. The first analysis included 29 patients receiving either monotherapy or combination therapy with the protease inhibitor ritonavir whose plasma HIV RNA levels rebounded from the point of greatest decline with mutations associated with resistance to ritonavir. The second analysis included a cohort of 102 patients who initially responded to randomized treatment with either monotherapy with ritonavir or combination therapy with ritonavir and zidovudine. METHODS: Durability of response was defined as the time from the initiation of therapy to the point at which plasma HIV RNA displayed a sustained increase of at least 0.6 log10 copies/ml from the nadir value. In the first analysis, durability of response was analyzed with respect to baseline HIV RNA, HIV RNA at the nadir, and the drop in HIV RNA from baseline to the nadir. In the second analysis, time to rebound was examined using Kaplan-Meier analysis, stratifying by either baseline HIV RNA or HIV RNA at the nadir. RESULTS: In both analyses, the durability of response was not highly associated with either baseline RNA or the magnitude of RNA decline from baseline. Instead, a strong relationship was observed between the durability of response and the nadir plasma HIV-1 RNA value (P < 0.01). The nadir in viral load was generally reached after 12 weeks of randomized therapy. CONCLUSIONS: Viral RNA determinations at intermediate timepoints may be prognostic of impending virologic failure of protease inhibitor therapy. Therapeutic strategies that allow intensification of initial antiretroviral regimens in the subset of patients with incomplete virological response before the emergence of high level resistance should be investigated.     

Single- versus multiple-dose antimicrobial prophylaxis for major surgery: a systematic review

BACKGROUND: Single-dose antimicrobial prophylaxis for major surgery is a widely accepted principle; recommendations have been based on laboratory studies and numerous clinical trials published in the last 25 years. In practice, single-dose prophylaxis has not been universally accepted and multiple-dose regimens are still used in some centres. Moreover, the principle has recently been challenged by the results of an Australian study of vascular surgery. The aim of this current systematic review is to determine the overall efficacy of single versus multiple-dose antimicrobial prophylaxis for major surgery and across surgical disciplines. METHODS: Relevant studies were identified in the medical literature using the MEDLINE database and other search strategies. Trials included in the review were prospective and randomized, had the same antimicrobial in each treatment arm and were published in English. Rates of postoperative surgical site infections (SSI) were extracted, 2 x 2 tables prepared and odds ratios (OR) [with 95% confidence intervals (95% CI)] calculated. Data were then combined using fixed and random effects models to provide an overall figure. In this context, a high value for the combined OR, with 95% CI > 1.0, indicates superiority of multiple-dose regimens and a low OR, with 95% CI < 1.0, suggests the opposite. A combined OR close to 1.0, with narrow 95% CI straddling 1.0, indicates no clear advantage of one regimen over another. Further subgroup analyses were also performed. RESULTS: Combined OR by both fixed (1.06, 95% CI, 0.89-1.25) and random effects (1.04, 95% CI, 0.86-1.25) models indicated no clear advantage of either single or multiple-dose regimens in preventing SSI. Likewise, subgroup analysis showed no statistically significant differences associated with type of antimicrobial used (beta-lactam vs other), blinded wound assessment, length of the multiple-dose arm (> 24 h vs 24 h or less) or type of surgery (obstetric and gynaecological vs other). CONCLUSIONS: Continued use of single-dose antimicrobial prophylaxis for major surgery is recommended. Further studies are required, especially in previously neglected surgical disciplines.