Wide angle crystal spectrometer for angularly and spectrally resolved X-ray scattering experiments

A novel wide angle spectrometer has been implemented with a highly oriented pyrolytic graphite crystal coupled to an image plate. This spectrometer has allowed us to look at the energy resolved spectrum of scattered x rays from a dense plasma over a wide range of angles (approximately 30 degrees ) in a single shot. Using this spectrometer we were able to observe the temporal evolution of the angular scatter cross section from a laser shocked foil. A spectrometer of this type may also be useful in investigations of x-ray line transfer from laser-plasmas experiments.

PCR-based determination of internal transcribed spacer (ITS) regions of ribosomal DNA of giant intestinal fluke, Fasciolopsis buski (Lankester, 1857) Looss, 1899

Fasciolopsis buski, the zoonotic intestinal flukes of pigs in South and Southeast Asia, is commonly prevalent in regions across Northeast India. Populations of the fluke collected from different parts of the region exhibit variations in morphology. The main objective of our study was to provide molecular characterization of the parasite so as to supplement morphological criteria, using ribosomal DNA cluster (rDNA), which is flanked by more conserved internal transcribed spacer (ITS) regions. We describe herein the ITS sequences of the parasite collected from swine hosts of Assam region. The ITS sequences of both egg and adult origins were found to be identical in length and composition. Phylogenetically, F. buski resembles closely the other members of family Fasciolidae, showing significant expectation value in the alignment. The results corroborate that the ITS sequences are not stage specific and are conserved through different stages of development of the fluke, and thus could be used as species markers.

Intermolecular complexation and phase separation in aqueous solutions of oppositely charged biopolymers

Turbidity measurements performed at 450nm were used to follow the process of complex formation, and phase separation in gelatin-agar aqueous solutions. Acid (Type-A) and alkali (Type-B) processed gelatin (polyampholyte) and agar (anionic polyelectrolyte) solutions, both having concentration of 0.1% (w/v) were mixed in various proportions, and the mixture was titrated (with 0.01 M HCl or NaOH) to initiate associative complexation that led to coacervation. The titration profiles clearly established observable transitions in terms of the solution pH corresponding to the first occurrence of turbidity (pH(C), formation of soluble complexes), and a point of turbidity maximum (pH(phi), formation of insoluble complexes). Decreasing the pH beyond pH(phi) drove the system towards precipitation. The values of pH(C) and pH(phi) characterized the initiation of the formation of intermolecular charge neutralized soluble aggregates, and the subsequent formation of microscopic coacervate droplets. These aggregates were characterized by dynamic light scattering. It was found that Type-A and -B gelatin samples formed soluble intermolecular complexes (and coacervates) with agar molecules through electrostatic and patch-binding interactions, respectively.

Study of gelatin–agar intermolecular aggregates in the supernatant of its coacervate

Intermolecular interaction leading to formation of aggregates between gelatin, a polyampholyte, and agar, a polysaccharide was studied in the supernatant of the complex coacervate formed by these biopolymers. Electrophoresis, laser light scattering and viscometry data were used to determine the interaction and the physical structure of these intermolecular soluble complexes by modeling these to be prolate ellipsoids of revolution (rod-like structures with well defined axial ratio and Perrin's factor). Solution ionic strength was found to reduce the axial ratio of these complexes implying the presence of screened polarization-induced electrostatic interaction between the two biopolymers.

Observation of extremely long spin relaxation times in an organic nanowire spin valve

Organic semiconductors that are pi-conjugated are emerging as an important platform for 'spintronics', which purports to harness the spin degree of freedom of a charge carrier to store, process and/or communicate information. Here, we report the study of an organic nanowire spin valve device, 50 nm in diameter, consisting of a trilayer of ferromagnetic cobalt, an organic, Alq3, and ferromagnetic nickel. The measured spin relaxation time in the organic is found to be exceptionally long-between a few milliseconds and a second-and it is relatively temperature independent up to 100 K. Our experimental observations strongly suggest that the primary spin relaxation mechanism in the organic is the Elliott-Yafet mode, in which the spin relaxes whenever a carrier scatters and its velocity changes.

A cohort study of correlation between body mass index and age at menarche in healthy Bengali girls

There are contradictory reports of lowering of age at menarche due to increasing body mass index (BMI) in the population. It is not known if a greater BMI at menarche is associated with a lower menarcheal age in healthy Bengali girls of normal nutrition. In this study the age at menarche was determined in 273 Bengali girls of middle income families. It was assessed whether BMI standard deviation scores (SDS) at menarche, BMI SDS at one year preceding menarche and BMI increments during that year were in correlation with age at menarche. The age of the girls with adequate nutrition was 8-16 years. They were examined for BMI, pubertal breast staging and age at menarche over a 4-year follow-up period. BMI SDS were calculated from National Center for Health Statistics (NCHS) normative data. The median age at menarche of 12.0 (range 10.0 - 16.0) years did not correlate with BMI SDS at menarche or BMI SDS at one year preceding menarche in this cohort. In univariate analysis, BMI increments for a given breast stage did not significantly lower the age at menarche. The change of BMI in the year preceding menarche did not correlate with age at menarche. The age at menarche in healthy Bengali girls of middle income families was similar to that of other Indian observations. There was no influence of BMI increments or that of BMI SDS prior to or at menarche on age at menarche.

Metal specificity of an iron-responsive element in Alzheimer's APP mRNA 5'untranslated region, tolerance of SH-SY5Y and H4 neural cells to desferrioxamine, clioquinol, VK-28, and a piperazine chelator

Iron closely regulates the expression of the Alzheimer's Amyloid Precursor Protein (APP) gene at the level of message translation by a pathway similar to iron control of the translation of the ferritin L- and H mRNAs by Iron-responsive Elements in their 5' untranslated regions (5'UTRs). Using transfection based assays in SH-SY5Y neuroblastoma cells we tested the relative efficiency by which iron, copper and zinc up-regulate IRE activity in the APP 5'UTR. Desferrioxamine (high affinity Fe3+ chelator), (ii) clioquinol (low affinity Fe/Cu/Zn chelator), (iii) piperazine-1 (oral Fe chelator), (iv) VK-28 (oral Fe chelator), were tested for their relative modulation of APP 5' UTR directed translation of a luciferase reporter gene. Iron chelation based therapeutic strategies for slowing the progression of Alzheimer's disease (and other neurological disorders that manifest iron imbalance) are discussed with regard to the relative neural toxic action of each chelator in SH-SY5Y cells and in H4 glioblastoma cells.

Magnetic reconnection and plasma dynamics in two-beam laser-solid interactions

We present measurements of a magnetic reconnection in a plasma created by two laser beams (1 ns pulse duration, 1 x 10(15) W cm(-2)) focused in close proximity on a planar solid target. Simultaneous optical probing and proton grid deflectometry reveal two high velocity, collimated outflowing jets and 0.7-1.3 MG magnetic fields at the focal spot edges. Thomson scattering measurements from the reconnection layer are consistent with high electron temperatures in this region.

Electric field modulation of infrared absorption at room temperature in electrochemically self assembled quantum dots

We report observation of electric-field-modulated infrared absorption at room temperature in electrochemically self-assembled CdS quantum dots produced by electrodepositing the semiconductor in 50-nm pores of an anodic alumina film. The absorption is associated with photoassisted real space transfer of electrons from the CdS dots to surrounding trap sites in the alumina. Similar absorption was observed in the past [Appl. Phys. Lett. 79, 4423 (2001)] and was the basis of a room temperature near infrared photodetector. An electric field modulates this absorption by altering the overlap between the wavefunctions of electronic states in the quantum dots and the trap states in the surrounding alumina, thereby affecting the matrix element for radiative transitions, similar to the quantum confined Stark or Franz-Keldysh effect. The ability to electrically modulate absorption in these structures can result in inexpensive infrared signal processing devices operating at room temperature.

Effect of microwave irradiated Methanosarcina barkeri DSM-804 on biomethanation

Methanosarcina barkeri DSM-804, a methanogenic bacterium, when exposed to microwave radiation of frequencies ranging from 13.5 to 36.5 GHz, showed faster growth in comparison to the unirradiated bacterial culture. Methane concentration in the biogas generated from the irradiated culture was higher than that from unirradiated one, which was to 76.3% on the 15th day of incubation at a microwave radiation frequency of 31.5 GHz, 10 dbm power when irradiated for 2 h. Microscopic study of pure culture revealed that the cells of M. barkeri were more in number and their cell diameter was enlarged by 20%. Inoculation of the culture in a biogas digester containing a combination of jute waste and vegetable market waste as substrate increased the efficacy of biomethanation and reduced its lag phase significantly.

HPV viral load determination during pregnancy as a possible cervical cancer risk

Pregnancy may be a risk factor for cervical human papillomavirus (HPV) infection due to associated increased hormonal level and immunosuppression. Although a majority of such infections are transient, persistent infection may lead to premalignant/malignant cervical lesion. The viral burden is thought to be an indicator for persistence of the infection and malignant transformation. To assess pregnancy as a risk factor for cervical HPV infection, we compared HPV prevalence and viral load among 25 pregnant women to those of 24 non-pregnant and 28 cervical cancer cases. HPV DNA was detected in the cervical cells by PCR using MY09/MY11 primers. HPV positive cases were retested with a low stringency PCR method to ascertain the viral load. HPV prevalences of 68%, 25% and 89% were observed among pregnant women, non-pregnant women and in the cervical cancer cases, respectively. High viral load was frequently (40%) observed in cervical cancer patients. Median viral copy number/cell did not vary much between the non-pregnant and pregnant women. However, pregnant women had a predominantly moderate viral load whereas the low viral load was more frequent in non-pregnant women. High viral load was found to be associated with the presence of HPV 16 in the cervical cancer cases as compared to pregnant/non-pregnant HPV infected women.

Survival of a patient with endopharyngeal common carotid blow out due to parapharyngeal abscess as an unusual complication of cholesteatoma

Parapharyngeal abscess as a complication of cholesteatoma is an uncommon entity. Endopharyngeal common carotid artery rupture due to parapharyngeal abscess is also uncommon, and these cases usually end fatally. We present a 17-year-old male with parapharyngeal abscess due to cholesteatoma who developed an endopharyngeal common carotid blow out and survived after common carotid ligation without any neurological sequalae.

Egr3 stimulation of GABRA4 promoter activity as a mechanism for seizure-induced up-regulation of GABA(A) receptor alpha4 subunit expression

GABA is the major inhibitory transmitter at CNS synapses. Changes in subunit composition of the pentameric GABA(A) receptor, including increased levels of alpha4 subunit in dentate granule cells and associated functional alterations such as increased zinc blockade of GABA currents, are hypothesized to be critical components of epileptogenesis. Here, we report that the minimal promoter of the human alpha4 subunit gene (GABRA4p), when used to drive reporter gene expression from adeno-associated viral vectors, controls condition-specific up-regulation in response to status epilepticus, defining a transcriptional mechanism for seizure-induced changes in levels of alpha4 subunit containing GABA(A) receptors. Transfection studies in primary hippocampal neurons show that inducible early growth response factor 3 (Egr3) up-regulates GABRA4p activity as well as the levels of endogenous alpha4 subunits. Given that Egr3 knockout mice display approximately 50% less GABRA4 mRNAs in the hippocampus and that increases in alpha4 and Egr3 mRNAs in response to pilocarpine-induced status epilepticus are accompanied by increased binding of Egr3 to GABRA4 in dentate granule cells, our findings support a role for Egr3 as a major regulator of GABRA4 in developing neurons and in epilepsy.

TEM/AFM investigation of size and surface properties of nanocrystalline ceria

A series of ceria nanoparticles were synthesized by using a microemulsion method. The effect of relative concentration of surfactant/water on the size and the surface roughness of ceria nanoparticles was examined using transmission electron microscopy (TEM) and atomic force microscopy (AFM) respectively. The investigation confirmed a relationship between the size and the roughness properties of the nanoceria as a function of the water to surfactant ratio. With increasing dilution of the surfactant, the size distribution became narrow such that average particle size decreased linearly as the ratio increased without affecting lower size threshold of particles (approximately 10 nm). The surface roughness, on the other hand was found to increase with increasing water to surfactant ratio implying diluted surfactant would provide rougher surface of ceria nanoparticles. The information can be used to tailor the adhesion properties of nanoceria by optimizing the size distribution as well as surface roughness as a function of water to surfactant ratio.

Selective anxiolysis produced by ocinaplon, a GABA(A) receptor modulator

Benzodiazepines remain widely used for the treatment of anxiety disorders despite prominent, often limiting side effects including sedation, muscle relaxation, and ataxia. A compound producing a robust anxiolytic action comparable to benzodiazepines, but lacking these limiting side effects at therapeutic doses (an anxioselective agent), would represent an important advance in the treatment of generalized anxiety disorder, and perhaps other anxiety disorders. Here we report that the pyrazolo[1,5-a]-pyrimidine, ocinaplon, exhibits an anxioselective profile in both preclinical procedures and in patients with generalized anxiety disorder, the most common of the anxiety disorders. In rats, ocinaplon produces significant muscle relaxation, ataxia, and sedation only at doses >25-fold higher than the minimum effective dose (3.1 mg/kg) in the Vogel "conflict" test. This anticonflict effect is blocked by flumazenil (Ro 15-1788), indicating that like benzodiazepines, ocinaplon produces an anxiolytic action through allosteric modulation of GABA(A) receptors. Nonetheless, in eight recombinant GABA(A) receptor isoforms expressed in Xenopus oocytes, the potency and efficacy of ocinaplon to potentiate GABA responses varied with subunit composition not only in an absolute sense, but also relative to the prototypical benzodiazepine, diazepam. In a double blind, placebo controlled clinical trial, a 2-week regimen of ocinaplon (total daily dose of 180-240 mg) produced statistically significant reductions in the Hamilton rating scale for anxiety scores. In this study, the incidence of benzodiazepine-like side effects (e.g., sedation, dizziness) in ocinaplon-treated patients did not differ from placebo. These findings indicate that ocinaplon represents a unique approach both for the treatment and understanding of anxiety disorders.

Switching time of nanowire memory

Cadmium sulfide nanowires of 10-nm diameter, electrodeposited in porous anodic alumina films, exhibit an electronic bistability that can be harnessed for non-volatile memory. The current-voltage characteristics of the wires show two stable conductance states that are well-separated (conductances differ by more than 4 orders of magnitude) and long lived (longevity > 1 year at room temperature). These two states can encode binary bits 0 and 1. Here we report measurements of the switching time to switch from the high- to the low-conductance state. These measurements also shed some light on the physical mechanisms underlying the bistability.