The dependence of the ideality factor on the charge density of a conjugated polymer (MEH-PPV) doped with some laser dyes

Blends made of poly[2-methyl-5-(2-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) conducting polymer and cresyl violet 670 (CV) and coumarin 460 (C₄₆₀) have been utilized for preparation of organic Schottky diodes. The I–V characteristics of these diodes are then determined and interpreted in terms of thermoionic emission (TIE) conduction process. Upon blending MEH-PPV with CV and C₄₆₀ dyes, the conduction is seen to completely be through TIE conduction. The turn on voltage for MEH-PPV diode is found to be 2.0 V and decreases with CV blending in contrast to the blend of MEH-PPV-C₄₆₀. The Schottky parameters are determined where the potential barrier is found to be around 0.75 V which is consistent with reported values. The charge densities of the respective blends are calculated and found to reduce by in MEH-PPV-C₄₆₀ blends while it has been enhanced in the CV samples by an order of magnitude compared that of MEH-PPV. The correlation between the ideality factor with the dielectric constant and the charge density is inspected. It is found that the ratio between the charge density of the polymeric blend and the charge density of the Al-electrode is crucial for obtaining low ideality factor.     

Berchemins A and B: Novel Enzyme‐Inhibiting Dimeric Lignan Glycosides from Berchemia pakistanica

Phytochemical investigation of Berchemia pakistanica by extensive bioassay‐guided fractionation resulted in the isolation of two novel dimeric lignan glycosides, berchemin A ( 1 ) and berchemin B ( 2 ), and of the four known compounds β‐sitosterol, β‐sitosterol 3‐O‐β‐D ‐glucoside, vavain, and daphnetin 8‐β‐D ‐glucoside. The structures of 1 and 2 were elucidated with the help of modern spectroscopic techniques, and the known compounds were identified by comparing their spectral data with those reported in the literature. Berchemins A and B were found to inhibit lipoxygenase and α‐glucosidase enzymes in a concentration‐dependent fashion.     

Pomegranate fruit extract inhibits UVB-induced inflammation and proliferation by modulating NF-κB and MAPK signaling pathways in mouse skin

There is considerable interest in the identification of natural agents capable of affording protection to skin from the adverse effects of solar ultraviolet B (UVB) radiation. Pomegranate (Punica granatum L.) fruit possesses as strong antioxidant, anti-inflammatory and antiproliferative properties. Recently, we have shown that oral feeding of pomegranate fruit extract (PFE) to mice afforded substantial protection from the adverse effects of single UVB radiation via modulation in early biomarkers of photocarcinogenesis. This study was designed to investigate the photochemopreventive effects of PFE (0.2%, wt/vol) after multiple UVB irradiations (180 mJ cm(-2), on alternative day, for a total of seven treatments) to the skin of SKH-1 hairless mice. Oral feeding of PFE to SKH-1 mice inhibited UVB-induced epidermal hyperplasia, infiltration of leukocytes, protein oxidation and lipid peroxidation. Immunoblot analysis demonstrated that oral feeding of PFE to mice inhibited UVB-induced (1) nuclear translocation and phosphorylation of nuclear factor kappa B/p65, (2) phosphorylation and degradation of IκBα, (3) activation of IKKα/ΙΚΚβ and (4) phosphorylation of mitogen-activated protein kinase proteins and c-Jun. PFE consumption also inhibited UVB-induced protein expression of (1) COX-2 and iNOS, (2) PCNA and cyclin D1 and (3) matrix metalloproteinases-2,-3 and -9 in mouse skin. Taken together, these data show that PFE consumption afforded protection to mouse skin against the adverse effects of UVB radiation by modulating UVB-induced signaling pathways.     

Determination of water soluble trace metals in airborne particulate matter using a dynamic extraction procedure with on-line inductively coupled plasma optical emission spectrometric detection

A novel continuous-flow system for the dynamic extraction of water soluble metal fractions in airborne particulate matter (APM) with subsequent inductively coupled plasma optical emission spectrometric (ICP-OES) analysis of derived extracts is presented. The fully automated extraction system with on-line multi-element detection offers enhanced sensitivity when compared to batch-wise counterparts; additionally it provides information about the extraction process. With the developed procedure detection limits in the order of 1.5 (Ba) to 8.0 (Ni) ng extractable mass per investigated sample could be achieved, which translates to method detection limits for soluble metal concentrations in APM ranging from 0.2 ng m⁻³ (Ba) to 0.9 ng m⁻³ (Fe). Reproducibility of analysis was determined by replicate measurement (n = 6) of an APM sample with an aerodynamic diameter ≤10 μm (PM10), derived results varied between 3.5% (Mn) and 12.1% (Ni) relative standard deviation. Method validation was accomplished by comparison of extracted soluble and remaining non-soluble fractions with the total metal contents of the investigated PM10 samples, showing an excellent mass balance for all elements. Application of the developed procedure for the analysis of water soluble metal fractions in PM10 samples (n = 16) from Linz (Austria) indicated a high variability of extractable fractions ranging from 11.7 ± 7.2% (Fe) to 48.8 ± 15.4% (Mn) of the total metal contents.     

The role of Ga substitution on magnetic and electromagnetic properties of nano-sized W-type hexagonal ferrites

A series of nano-sized single phase W-type SrGa_xZn₂Fe_16?xO₂₇ (x = 0.0, 0.1, 0.2, 0.3, 0.4) hexaferrites prepared by sol gel technique and sintered at 950 °C have been investigated. The thermal decomposition behavior of nitrate–citrate gel of as prepared powder was investigated by means of DTA/TGA analysis. The sintered powders were characterized by FTIR, XRD, SEM, VSM and vector network analyzer (VNA). X-ray diffraction patterns for pure and substituted W-type hexaferrites show the single phase structure with no impurity phase. The lattice parameters (a and c) decrease with the increase of Ga contents (x). The grain size estimated from SEM images is in the range of 139–76 nm which confirms the nanocrystalline nature of the investigated samples. The saturation magnetization (M_s) decreases whereas coercivity (H_c) increases with the increase of Ga contents (x). The values of H_c for all of the investigated samples lie in the range of few hundred oersteds which is one of the necessary conditions for EM materials. The microwave absorption property is enhanced in the frequency (with respect to ?20 dB) from 0.5 to 13 GHz, and the bandwidth reaches 0.899 GHz. The attenuation peak value is ?32 dB at the matching thickness of 3.4 mm.     

Pressure induced frequency shifts in the atomic iodine laser

The frequency of oscillation of an iodine photodissociation laser has been measured for argon buffer gas pressures up to 7 atmospheres. The variation in frequency of the 1.315 μm transition can be explained solely by the overlapping of the hyperfine split transitions at high pressures, and no evidence is obtained for a collisional frequency shift. A pressure broadening parameter of 4.5 MHz/torr for argon-iodine collisions is deduced from the observed frequency shifts.