Tunable Ampere phase plate for low dose imaging of biomolecular complexes

A novel device that can be used as a tunable support-free phase plate for transmission electron microscopy of weakly scattering specimens is described. The device relies on the generation of a controlled phase shift by the magnetic field of a segment of current-carrying wire that is oriented parallel or antiparallel to the electron beam. The validity of the concept is established using both experimental electron holographic measurements and a theoretical model based on Ampere’s law. Computer simulations are used to illustrate the resulting contrast enhancement for studies of biological cells and macromolecules

Micromachining with square-Shaped 1 ns-Long pulses from an all-Fiber Yb-Doped laser-Amplifier system

We demonstrate micromachining with 1ns-long pulses from an all-fiber laser. Fiber lasers generating uncompressible long pulses have been ignored as undesired operational modes, however their robust, low-repetition-rate operation is well suited to micromachining. © 2011 Optical Society of America

The role of the family in attributing meaning to living with HIV and its stigma in Turkey

Stigma attached to HIV/AIDS remains a global problem, with severe negative consequences for people living with HIV (PLHIV). Family support is fundamental for PLHIV’s psychological and physical well-being. HIV-related stigma is high in Turkey, where HIV/AIDS prevalence is low and the epidemic is not considered a priority. Based on qualitative data generated with HIV-positive women and men, this article explores the process of stigmatization, as experienced and perceived by PLHIV in Turkey, focusing on the institution of the family. Results indicated that enacted stigma from family members is lower than anticipated. While most participants’ narratives showed patterns of support rather than rejection from families, the strong expectations around the cultural value attributed to “the family” are found to be the main facilitators of internalized stigma. The article critically discusses the meaning and implications of family support, addressing the role of patriarchal values attributed to womanhood, manhood, and sexuality in Turkey

Understanding atmospheric organic aerosols via factor analysis of aerosol mass spectrometry: a review

Organic species are an important but poorly characterized constituent of airborne particulate matter. A quantitative understanding of the organic fraction of particles (organic aerosol, OA) is necessary to reduce some of the largest uncertainties that confound the assessment of the radiative forcing of climate and air quality management policies. In recent years, aerosol mass spectrometry has been increasingly relied upon for highly time-resolved characterization of OA chemistry and for elucidation of aerosol sources and lifecycle processes. Aerodyne aerosol mass spectrometers (AMS) are particularly widely used, because of their ability to quantitatively characterize the size-resolved composition of submicron particles (PM1). AMS report the bulk composition and temporal variations of OA in the form of ensemble mass spectra (MS) acquired over short time intervals. Because each MS represents the linear superposition of the spectra of individual components weighed by their concentrations, multivariate factor analysis of the MS matrix has proved effective at retrieving OA factors that offer a quantitative and simplified description of the thousands of individual organic species. The sum of the factors accounts for nearly 100% of the OA mass and each individual factor typically corresponds to a large group of OA constituents with similar chemical composition and temporal behavior that are characteristic of different sources and/or atmospheric processes. The application of this technique in aerosol mass spectrometry has grown rapidly in the last six years. Here we review multivariate factor analysis techniques applied to AMS and other aerosol mass spectrometers, and summarize key findings from field observations. Results that provide valuable information about aerosol sources and, in particular, secondary OA evolution on regional and global scales are highlighted. Advanced methods, for example a-priori constraints on factor mass spectra and the application of factor analysis to combined aerosol and gas phase data are discussed. Integrated analysis of worldwide OA factors is used to present a holistic regional and global description of OA. Finally, different ways in which OA factors can constrain global and regional models are discussed

Effects of enzymatic treatment on various spun yarn fabrics [Efekt obróbki enzymatycznej dzianin wykonanych z prz?dz snutych ró·znymi sposobami]

Pilling and fuzz, which were not a problem at all in previous years (especially for cotton fabrics), have become a major problem recently. Fibre type, the yarn spinning system, fabric type, and finishing process play an important role in the pilling properties of fabrics. In this study, single jersey fabrics knitted with 100% combed, carded and open-end cotton yarns were used. An enzymatic process for fuzz reduction was applied at different stages, and the effect of this on pilling, strength, weight loss and the colour differences of the fabric were tested. Previous studies on this subject were carried out with small-scale samples, and therefore do not reflect the facts exactly. For this reason, all the phases of this study were specifically carried out under common working conditions like those prevailing in industry

Schulz-Snyder Phase Retrieval Algorithm as an Alternating Minimization Algorithm

We derive the Schulz-Snyder phase retrieval algorithm as an alternating minimization method, and discuss its advantages and drawbacks. An annealing-type Schulz-Snyder algorithm is proposed to avoid convergence to nonglobal solutions. Numerical experiments which suggest the effectiveness of the proposed method are presented

Antioxidant responses of tolerant and sensitive barley cultivars to boron toxicity

Effect of boron toxicity on antioxidant response of sensitive (Hamidiye) and tolerant (Anadolu) barley (Holgarium vulgar) cultivars was investigated. Eight days old hydroponically grown seedlings were subjected to 5 and 10 mM boric acid treatments for 5 days. Growth parameters (dry-wet weight), protein, proline, MDA, H2O2 contents, membrane damage and activities of superoxide dismutase (SOD). ascorbate peroxidase (APX), catalase (CAT) and glutathion reductase (GR) was evaluated in root and shoot tissues. Compared with controls (no boric acid treatment) boron toxicity resulted in a reduction in root weights and did not cause any significant change in protein contents. Boric acid treatment did not cause significant (P > 0.05) changes in proline and H2O2 contents of both tissues and cultivars. On contrary, NIDA contents and electrolyte leakage exhibited a dose dependent increase in shoots whereas no significant change was observed in root tissues. Higher extend of membrane damage was observed in leaves of the sensitive cultivar. Total SOD, CAT and GR activities in shoot tissue of both cultivars did not change significantly whereas significantly higher APX activities was observed at 10 mM boric acid treatments. Significant increases in total SOD, CAT and decrease in GR activities was observed in roots of the sensitive cultivar. Roots of resistant cultivar, on contrary, exhibited enhanced CAT and decreased APX activity whereas no significant changes was observed in total SOD and GR activities. Our data suggest that. boron toxicity induced membrane damage in barley leaves, do not involve active oxygen species and antioxidant enzyme activity is not a critical factor in boron toxicity tolerance mechanism. To the best of our knowledge, this is the first report on antioxidant response of barley seedlings under boron toxicity. (C) 2003 Elsevier Science Ireland Ltd. All rights reserved

Identification and characterization of hydrolytic enzymes from the midgut of Sunn Pest of wheat (Eurygaster integriceps)

To help in the development of Sunn Pest-resistant transgenic plants employing protease or alpha-amylase inhibitors, midgut hydrolytic enzymes of Sunn Pest (Eurygaster integriceps, Put.) (Heteroptera: Scutelleridae) were identified and characterized biochemically. We observed levels of very low proteolytic activity of trypsin (3 nmoles/min/mg), elastase (0.66 nmoles/min/mg) and leucine aminopeptidase-like (14.4 nmoles/min/mg) proteases, but no chymotrypsin and papain-like activity. Proteolytic activities were insensitive to inhibition by soybean trypsin inhibitor (SBTI) and aprotinin, but were inhibited to varying degrees (40-100%) by the synthetic protease inhibitors PMSF, TPCK, CdCl2 and CuCl2. Compared to proteolytic activity, significantly higher amylolytic activity (4.45 mmoles/min/mg) was observed. Alpha-amylase activity was found to be resistant to inhibition by bean and chickpea alpha-amylase inhibitors, and only slightly inhibited by wheat (36.9 +/- 1.8%) and maize (40.2 +/- 2.8) alpha-amylase inhibitors. Here, we report on the biochemical properties of digestive enzymes from Sunn Pest midgut, and their inhibition patterns by several synthetic and natural hydrolytic enzyme inhibitors