Centrosymmetric, Skew Centrosymmetric and Centrosymmetric Cauchy Tensors

Recently, Zhao and Yang introduced centrosymmetric tensors. In this paper, we further introduce skew centrosymmetric tensors and centrosymmetric Cauchy tensors, and discuss properties of these three classes of structured tensors. Some sufficient and necessary conditions for a tensor to be centrosymmetric or skew centrosymmetric are given. We show that, a general tensor can always be expressed as the sum of a centrosymmetric tensor and a skew centrosymmetric tensor. Some sufficient and necessary conditions for a Cauchy tensor to be centrosymmetric or skew centrosymmetric are also given. Spectral properties on H-eigenvalues and H-eigenvectors of centrosymmetric, skew centrosymmetric and centrosymmetric Cauchy tensors are discussed. Some further questions on these tensors are raised

Cell signaling promoting protein carbonylation does not cause sulfhydryl oxidation: implications to the mechanism of redox signaling

Reactive oxygen species (ROS) have been recognized as second messengers, however, targeting mechanisms for ROS in cell signaling have not been defined. While ROS oxidizing protein cysteine thiols has been the most popular proposed mechanism, our laboratory proposed that ligand/receptor-mediated cell signaling involves protein carbonylation. Peroxiredoxin-6 (Prx6) is one protein that is carbonylated at 10 min after the platelet-derived growth factor (PDGF) stimulation of human pulmonary artery smooth muscle cells. In the present study, the SulfoBiotics Protein Redox State Monitoring Kit Plus (Dojindo Molecular Technologies) was used to test if cysteine residues of Prx6 are oxidized in response to the PDGF stimulation. Human Prx6 has a molecular weight of 25 kDa and contains two cysteine residues. The Dojindo system adds the 15 kDa Protein-SHifter if these cysteine residues are reduced in the cells. Results showed that, in untreated cells, the Prx6 molecule predominantly exhibited the 55 kDa band, indicating that both cysteine residues are reduced in the cells. Treatment of cells with 1 mM H 2O 2 caused the disappearance of the 55 kDa band and the appearance of a 40 kDa band, suggesting that the high concentration of H 2O 2 oxidized one of the two cysteine residues in the Prx6 molecule. By contrast, PDGF stimulation had no effects on the thiol status of the Prx6 molecule. We concluded that protein carbonylation is a more sensitive target of ROS during ligand/receptor-mediated cell signaling than sulfhydryl oxidation

Microstructures and mechanical properties of tungsten wire/particle reinforced Zr57Nb5Al10Cu15.4Ni12.6 metallic glass matrix composites

Tungsten wire or particle reinforced metallic glass matrix composites are produced by infiltrating liquid Zr57Nb5Al10Cu15.4Ni12.6 (Vit106) into tungsten reinforcements at 1150 and at 1425 K. X-ray diffraction, differential scanning calorimetry, and scanning electron microscopy are carried out to characterize the composite. The matrix of the composite processed at 1150 K is mostly amorphous, with some embedded crystals. During processing, tungsten dissolves in the glass-forming melt and upon quenching precipitates over a relatively narrow zone near the interface between the tungsten and matrix. In the composites processed at 1425 K, tungsten dissolves in the melt and diffuses through the liquid medium, and then reprecipitates upon quenching. The faster kinetics at this high temperature results in a uniform distribution of the crystals throughout the matrix. Mechanical properties of the differently processed composites containing wires and particles are compared and discussed. The composites exhibit a plastic strain failure of up to 16% without sacrificing the high-failure strength, which is comparable to monolithic Vit106

Production Of Crude Biopolymer From Bacteria In Drainage System

This work focuses on the extraction of biopolymer from bacteria in relation to wastewater treatment, specifically in flocculation process. Three isolates of bacterial strain (WIR, WRA, WIA) which are able to produce biopolymers as flocculants were identified from industrial and residential drainage systems. These bacteria were identified as Bacillus megaterium BMRA, Bacillus megaterium BMIR and Bacillus subtilis BSIA through physiological characteristics (mucoid, slimy and ropy) and the partial sequences of their 16SrRNA. Crude biopolymers CWIR (industrial + residential) and CWRA (residential) were produced by Bacillus megaterium BMIR and BMRA while CWIA (industrial) was extracted from Bacillus subtilis BSIA. These bacteria produced their respective biopolymers at 40ºC given a two-day incubation period, with pH 7.0 ± 0.03. The crude biopolymers were recovered from the supernatant of the culture broth by ethanol precipitation and vacuum-dried in vacuum oven. CWIR, CWRA and CWIA contained 4.01%, 5.20% and 5.45% of protein respectively. Total sugar content in each biopolymer was 1.48% for CWIR, 1.65% for CWRA and 1.79% for CWIA. Elemental analyses showed that the CWIR obtained had 31.60% of C, 4.81% of H and 6.32% of N, while WRA contained 31.37% of C, 5.02% of H and 6.12% of N. WIA showed a composition comprising 31.25% of C, 4.88% of H and 5.69% of N. The molecular weight for each of the biopolymers CWIA, CWIR and CWRA was measured at 31.788 kDa, 55.344 kDa and 38.791 kDa respectively

The Caltech Submillimeter Observatory

A brief description of the history and technology of the Caltech Submillimeter Observatory (CSO) is presented. The design of the 10.4 m Leighton telescope is discussed and also the methods used for fine adjustments of the surface. The dome design is explained, plus a short description is given of the technology of the detectors

Supporting the planning of a community fisheries monitoring and evaluation database: a collaborative project undertaken by CFDO, FLD, STREAM, VSO and AYAD

Cambodia is one of the poorest countries in the world; much of its population live in rural areas and many live below the local poverty line. The management of common property aquatic resources is of over-riding importance to food security and sustainable rural development in Cambodia. Aquatic resources are utilized principally by subsistence fishers and the landless, for whom aquatic resource use is an important livelihood activity. Subsistence fishers access mainly the rivers, lakes and inundated forests in Tonle Sap provinces, the lower Mekong and Bassac regions and the upper part of the Mekong. Freshwater capture fisheries probably contribute more to national food security and the national economy in Cambodia than in any other country in the world. (PDF contains 52 pages