S. S. Hussain

Enhanced and reproducible neutron emission from a plasma focus with pre-ionization induced by depleted uranium (U238)

The effect of pre-ionization induced by depleted uranium (92U238) around the insulator sleeve on the neutron emission of (1.8?3.3?kJ) plasma focus device is investigated by employing time resolved and time integrated neutron detectors. The maximum average neutron yield of 2.5 ? 108 is recorded at 3.5?mbar without pre-ionization, which increases up to 3.85 ? 108 with pre-ionization. It is found that the pre-ionization enhances neutron yield, about (50 ? 5)%, broadens the neutron emission pressure range and improves shot-to-shot reproducibility of plasma focus operation for neutron emission. The pinhole images of charged particles emitting zones indicate that the pre-ionization increases the high temperature plasma volume.

X-ray emission from a plasma focus with high-Z inserts at the anode tip

X-ray emission in different energy windows, from a low energy Mather-type plasma focus by employing high Z inserts at the anode tip is investigated. Quantrad Si pin diodes with differential filtering are employed as time-resolved x-ray detectors, whereas a pinhole camera is used for time-integrated analysis. The x-ray flux from the focus region is found to be measurable within the pressure range 0.25–3.5 mbar of hydrogen. The maximum emission in 4π-geometry is found to be 29.4±0.2 J, 3.43±0.05 J and 4.00±0.02 J with Pb, W and Mo inserted anodes, respectively, and corresponding wall plug efficiencies for x-ray generation are 1.28%, 0.15% and 0.2%. The x-ray emission is found predominantly as a result of electron beam activity on the anode tip, which is confirmed by the images recorded by the pinhole camera.

SOFT X-RAY EMISSION IN THE (1.0–1.5 KEV) WINDOW WITH NITROGEN FILLING IN A LOW ENERGY PLASMA FOCUS

A study of soft X-ray emission in the 1.0–1.5 keV energy range from a low energy (1.15 kJ) plasma focus has been conducted. X-rays are detected with the combination of Quantrad Si PIN-diodes masked with Al (50 μm), Mg (100 μm) and Ni (17.5 μm) filters and with a pinhole camera. The X-ray flux is found to be measurable within the pressure range of 0.1–1.0 mbar nitrogen. In the 1.0–1.3 keV and 1.0–1.5 keV windows, the X-ray yield in 4π-geometry is 1.03 J and 14.0-J, respectively, at a filling pressure of 0.25 mbar and the corresponding efficiencies are 0.04% and 1.22%. The total X-ray emission in 4π-geometry is 21.8 J, which corresponds to the system efficiency of about 1.9%. The X-ray emission is found dominantly as a result of the interaction of energetic electrons in the current sheath with the anode tip. Images recorded by the pinhole camera confirm the emission of X-rays from the tip of the anode.

Mutation in the Tight-Junction Gene Claudin 19 (CLDN19) and Familial Hypomagnesemia, Hypercalciuria, Nephrocalcinosis (FHHNC) and Severe Ocular Disease

Background/Aims: Familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC) is a rare renal tubular disorder complicated by progressive renal failure during childhood or adolescence. Recently, causative mutations in the CLDN19 gene have been identified in FHHNC patients presenting with severe ocular involvement. The aim of the study was to investigate the molecular genetic defect underlying FHHNC in a consanguineous Pakistani family. Methods: Clinical and biochemical parameters of the proband were studied during the follow-up period over 5 years. Genotyping of 7 members of the family was performed by amplifying microsatellite markers, tightly linked to the CLDN16 and CLDN19 genes. The two genes were sequenced directly in an automated sequencer. PCR-RFLP assay and bioinformatic analysis were performed to verify the identified mutation. Results: Genotyping revealed that the proband was homozygous for the marker loci tightly linked to the CLDN19 gene. Sequence analysis in the proband revealed homozygosity for a novel missense mutation in exon 3 of the CLDN19 gene (389G>A) resulting in G130D amino acid substitution. Bioinformatic analysis supported the pathogenicity of the identified mutation. Family screening revealed nephrolithiasis in 3 of 6 (50%) heterozygous carriers of the pathogenic mutation. Conclusion: This study supports the fundamental role of claudin 19 for magnesium homeostasis, normal tubular structures in the kidney, and undisturbed organization and development of the retina.

Molecular study of X-linked ichthyosis: report of a novel 2-bp insertion mutation in the STS and a very rare case of homozygous female patient.

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Effect of preionization on soft x-ray emission and plasma dynamics in a small plasma focus system

A conventional plasma focus device is operated in a volumetric mixture ratio of Ne+He (50:50) to produce a hot and dense plasma without and with preionization which emits radiation in the soft x-ray region. A ring of depleted uranium is employed as a preionization source. Quantrad silicon PIN diodes and a multipinhole camera with suitable filters are used for x-ray analysis. X-ray emission in 4π geometry is measured as a function of Ne+He mixture filling pressure. The experimental results show that preionization not only enhances the yield of the soft x-rays but also increases the focus duration and shot to shot reproducibility of plasma focus. The x-ray images reveal that preionization makes the focus filament symmetric and also enhances its volume.

Trace-Rare-Gas Optical Emission Spectroscopy of Nitrogen Plasma Generated at a Frequency of 13.56 MHz

Optical emission spectroscopic measurement of trace rare gas is carried out to determine the density of nitrogen (N) atom, in a nitrogen plasma, as a function of filling pressure and RF power applied. 2% of argon, used as an actinometer, is mixed with nitrogen. In order to normalize the changes in the excitation cross section and electron energy distribution function at different operational conditions, the Ar-I emission line at 419.83 nm is used, which is of nearly the same excitation efficiency coefficient as that of the nitrogen emission line at 493.51 nm. It is observed that the emission intensity of the selected argon and atomic nitrogen lines increases with both pressure and RF power, as does the nitrogen atomic density.

Effect of anode shape on correlation of neutron emission with pinch energy for a 2.7kJ Mather-type plasma focus device

Correlation of neutron emission with pinch energy for a Mather-type plasma focus energized by a single capacitor 12.5μF, 21kV (2.7kJ) is investigated by employing time resolved and time integrated detectors for two different anode shapes. The maximum average neutron yield of about 1.3×108 per shot is recorded with cylindrical anode, that increases to 1.6×108 per shot for tapered anode. At optimum pressure the input energy converted to pinch energy is about 24% for cylindrical anode as compared to 36% for tapered anode. It is found that the tapered anode enhances neutron flux about 25±5% both in axial and radial directions and also broadens the pressure range for neutron emission as well as pinch energy. The neutron yield and optimum gas filling pressures are found strongly dependent on the anode shape.

Characterization of RF He-N2/Ar mixture plasma via Langmuir probe and optical emission spectroscopy techniques

A Magnetic Pole Enhanced inductively coupled RF He-  N2/  Ar plasma is characterized using a Langmuir probe and optical emission spectroscopy (OES) techniques. The effect of helium mixing on electron density  (ne) and temperature  (Te), electron energy probability functions (EEPFs), [ N] atomic density, and N2  dissociation is investigated. A Langmuir probe and a zero slope method based on trace rare gas-optical emission spectroscopy (TRG-OES) are employed to measure the electron temperature. It is noted that the electron temperature shows an increasing trend for both methods. However, the temperature measured by a zero slope method Te(Z·S) approaches the temperature measured by a Langmuir probe; Te(L·P) at 56% and above helium concentration in the discharge. “Advance actinometry” is employed to monitor the variation in [ N] atomic density with helium concentration and gas pressure. It is noted that [ N] atomic density increases at 56% and above helium in the discharge, which is consistent with the trend ...

Study of the effect of antiviral therapy on homocysteinemia in hepatitis C virus- infected patients.

BackgroundHepatitis C virus (HCV) infection is one of the leading causes of chronic liver disease (CLD). About 80% of those exposed to the virus develop a chronic infection. Hyperhomocysteinemia, which is an independent risk factor for atherosclerotic vascular disease and thromboembolism, may develop in HCV-infected patients although altered alanine amino transferase (ALT) enzyme levels are generally associated with damage to liver cells. The gold standard therapy for chronic hepatitis C patients is pegylated interferon combined with an anti-viral drug (ribavirin). The current study aimed to investigate the effect of antiviral therapy on plasma homocysteine (Hcy) levels in HCV patients in addition to other parameters.Methods532 HCV-infected patients and 70 healthy controls were recruited for the study. All patients were subjected to laboratory investigations including HCV-RNA levels, complete blood cell counts, serum levels of homocysteine, ALT, alkaline phosphatase (ALP), lipid profile and liver ultrasonographic examination. The outcome of treatment with pegylated interferon α plus ribavirin treatment and sustained virologic response (SVR) was determined 6–9 months post-therapy.ResultsHyperhomocysteinemia was found in 91.35% of HCV-infected patients. The difference in plasma Hcy concentrations reached statistical significance between the patient and control groups. ALT, cholesterol and triglycerides (TGs) levels were found higher than normal in the patients group. After receiving a combined therapy for 24 weeks, 43.66% patients showed an SVR (responders); 30.98% patients were non-responders while 25.35% patients initially responded to therapy but again retrieved positive status of HCV infection six months post-therapy (relapse-cirrhotic patients). The mean levels of plasma Hcy, ALT and ALP were significantly reduced in responders within 10 weeks of therapy when compared with non-responders and relapse-cirrhotic patients.ConclusionElevated homocysteine levels in serum due to HCV infection can be reduced to normal range with the standard interferon α plus ribavirin treatment. This study highlights the significance of the measurement of serum homocysteine levels in the diagnosis and monitoring of HCV infection treatment in addition to other laboratory parameters.