Determination of mass density, dielectric, elastic, and piezoelectric constants of bulk GaN crystal

Mass density, dielectric, elastic, and piezoelectric constants of bulk GaN crystal were determined. Mass density was obtained from the measured ratio of mass to volume of a cuboid. The dielectric constants were determined from the measured capacitances of an interdigital transducer (IDT) deposited on a Z-cut plate and from a parallel plate capacitor fabricated from this plate. The elastic and piezoelectric constants were determined by comparing the measured and calculated SAW velocities and electromechanical coupling coefficients on the Z- and X-cut plates. The following new constants were obtained: mass density p = 5986 kg/m(3); relative dielectric constants (at constant strain S) ε(S)(11)/ε(0) = 8.6 and ε(S)(11)/ε(0) = 10.5, where ε(0) is a dielectric constant of free space; elastic constants (at constant electric field E) C(E)(11) = 349.7, C(E)(12) = 128.1, C(E)(13) = 129.4, C(E)(33) = 430.3, and C(E)(44) = 96.5 GPa; and piezoelectric constants e(33) = 0.84, e(31) = -0.47, and e(15) = -0.41 C/m(2).     

Creation of arteriovenous fistulae for hemodialysis in octogenarians

Elderly patients, defined as octogenarians and nonagenarians, are an increasing population entering renal replacement therapy. Advanced age appears as an exclusive factor negatively influencing dialysis practice. Elderly patients are referred late for the initiation of hemodialysis and more likely are offered catheters rather than arteriovenous fistulae (AVF), which increase mortality and negatively affect quality of life. We present our approach to the creation of vascular access for hemodialysis in this demanding population. In 2006–2012, 39 patients aged 85.9 ± 2.05 with end‐stage renal disease, mainly resulting from ischemic nephropathy, were admitted to the Department of Nephrology to establish permanent vascular access for hemodialysis: preferably AVF. Temporary dialysis catheters were implanted in uremic emergency to bridge the time to fistula creation/maturation. AVF was attempted in 87.2% of the patients. Primary AVF function was achieved in 54% of the patients. Cumulative proportional survival of AVF at months 12 and 24 was 81.5%. Ninety‐four percent of AVF were localized on the forearm: 74% in the distal and 20% in the proximal part. Mean duration of hemodialysis therapy was 20.80 ± 19.45 months. The mean time of AVF use was 15.9 ± 20.2 months. Until present, 38% have been dialyzed using AVF for 31.0 ± 18.8 months. Five patients died with functioning fistula. Eight patients initiated hemodialysis therapy with fistula. During further observation, the use of AVF increased to 62%. Elderly patients should not be denied creation of AVF as a rule. The outcome of AVF benefits more from acknowledging individual vascular conditions rather than age of the patient.     

Bright superior mirages

Superior mirages of unusual brightness are occasionally observed. Two such cases, photographed over the frozen surface of Lake Winnipeg, Canada, are documented. Visually, these mirages appear as featureless bright barriers far out on the lake. They are just images of the lake ice, yet the luminance in one case was 2.5 times (in the other, 1.7 times) the luminance of the ice surface in front of the mirage. The mirage itself can be modeled by means of a conduction inversion, but a proper explanation of the brightness is not yet available.     

Protection of normal cells from irradiation bystander effects by silica-flufenamic acid nanoparticles

The development of a myriad of nanoparticles types has opened new possibilities for the diagnostics and treatment of many diseases, especially for cancer. However, most of the researches done so far do not focus on the protection of normal cells surrounding a tumor from irradiation bystander effects that might lead to cancer recurrence. Gap-junctions are known to be involved in this process, which leads to genomic instability of neighboring normal cells, and flufenamic acid (FFA) is included in a new group of gap-junction blockers recently discovered. The present work explores the use of mesoporous silica nanoparticles MCM-41 functionalized with 3-Aminopropyltriethoxysilane (APTES) for anchoring the flufenamic acid for its prolonged and controlled release and protection from radiation bystander effects. MCM-41 and functionalized samples were structurally and chemically characterized with multiple techniques. The biocompatibility of all samples was tested in a live/dead assay performed in cultured MRC-5 and HeLa cells. HeLa cells cultured were exposed to 50?Gy of gamma-rays and the media transferred to fibroblast cells cultured separately. Our results show that MCM-41 and functionalized samples have high biocompatibility with MCR-5 and HeLa cells, and most importantly, the FFA delivered by these NPs was able to halt apoptosis, one of main bystander effects.     

Single‐lumen tunneled catheter: An old but useful option

We report a case of long‐term uneventful catheter use in a patient with previous recurrent vascular access dysfunction and infection. A single‐lumen tunneled catheter was inserted into the left internal jugular vein after a failed attempt of dual‐lumen permanent catheter placement. The follow‐up since device implantation has exceeded 5 years without any complications related to vascular access.     

Optimal versus heuristic scheduling of surface mount technology lines

This paper presents and compares an exact and a heuristic approach for scheduling of printed wiring board assembly in surface mount technology (SMT) lines. A typical SMT line consists of several assembly stations in series and/or in parallel, separated by finite intermediate buffers. The objective of the scheduling problem is to determine the detailed sequencing and timing of all assembly tasks for each individual board, so as to maximize the line's productivity, which is defined in terms of makespan for a mix of board types. The limited intermediate buffers between stations result in a scheduling problem with machine blocking, where a completed board may remain on a machine and block it until a downstream machine becomes available. In addition, limited machine availability due to scheduled downtimes is considered. The exact approach is based on a mixed integer programming formulation that can be used for optimization of assembly schedules by using commercially available software for integer programming, whereas the heuristic approach is designed as a combination of tabu search and a set of dispatching rules. Numerical examples modelled after real-world SMT lines and some computational results are provided to illustrate and compare the two approaches.     

Gallium phosphide nanowires as a substrate for cultured neurons

Dissociated sensory neurons were cultured on epitaxial gallium phosphide (GaP) nanowires grown vertically from a gallium phosphide surface. Substrates covered by 2.5 microm long, 50 nm wide nanowires supported cell adhesion and axonal outgrowth. Cell survival was better on nanowire substrates than on planar control substrates. The cells interacted closely with the nanostructures, and cells penetrated by hundreds of wires were observed as well as wire bending due to forces exerted by the cells.     

Prinzip-Analyse von zwei Röntgen-Verformungsmeßverfahren

Erläuterung der Methoden zur Ermittlung mechanischer Spannungen unter besonderer Berücksichtigung der räumlichen Verhältnisse bei der Röntgenmessung. Darstellung der Verformungsgeometrie und der daraus abgeleiteten Meßverfahren. Vergleichende Gegenüberstellung des Röntgen-φ-Integralverfahrens mit dem Röntgen-ψ-Integralverfahren.     

Ceranapril and cerebral blood flow autoregulation

In order to investigate the levels of the polycyclic aromatic hydrocarbons, mainly benzo[a]pyrene because of its carcinogenicity, 55 samples of smoke flavour and smoked foods were analysed. The samples tested included 11 samples of liquid smoke flavour and 44 samples of smoked foods like bacon, loin, turkey, sausage, ox rib, etc. from different brands. A liquid chromatographic method was developed using a fluorescence detector. Benzo[a]pyrene was found in 73% of the liquid smoke flavour samples analysed. The levels varied from 0.1 to 336.6 micrograms/kg. Three liquid smoke flavour samples showed levels of benzo[a]pyrene above the maximum level recommended by FAO/WHO (10 micrograms/kg). From the total of 44 smoked food samples analysed, benzo(a)pyrene was detected in 23 samples (52%). The levels varied from 0.1 to 5.9 micrograms/kg. Anthracene and fluoranthene, non-carcinogenic polycyclic aromatic hydrocarbons, were found in almost all the samples analysed. Benzo[ghi]perylene, 3,4-benzofluoranthene and 1,2,3,4-dibenzopyrene were not found in any of the 55 samples analysed.     

Content of amino acids and the quality of protein in Brussels sprouts,both raw and prepared for consumption

The aim of the investigation was to evaluate the content of amino acids and the quality of protein in Brussels sprouts. The investigation included the raw material, cooked sample and two types of frozen product stored at ?20 °C for 12 months and then prepared for consumption. The frozen products investigated were obtained using the traditional method (blanching before freezing) and the modified method (cooking before freezing, then defrosting and heating in microwave oven after refrigerated storage) of the ready-to-eat type. Brussels sprouts, both fresh and prepared for consumption, were a good source of protein and amino acids. Proline and glutamic acid were dominating; leucine and tyrosine with phenylalanine were limiting amino acids. The product obtained by modified method contained 16% less amino acids in 16 g N than the raw material and 14% less than the raw material after cooking, and also 10% lower than that of the traditionally obtained product.