Search Results - (Author, Cooperation:Z. Hussain)

2018-09-19

American Physical Society (APS)

0031-9007

1079-7114

Physics

Condensed Matter: Electronic Properties, etc.

2014-01-18

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

2011-03-26

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

2018-11-10

Institute of Physics (IOP)

1757-8981

1757-899X

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

2018-12-14

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Geosciences

Computer Science

Medicine

Natural Sciences in General

Physics

Materials Science, Physics

1089-7550

AIP Digital Archive

Physics

Electronic Resource

1089-7550

AIP Digital Archive

Physics

The reduction of pentavalent vanadium ions in aqueous solutions upon laser irradiation has been confirmed by using optical absorption and fluorescence techniques. X-ray photoelectron spectroscopy (XPS) study revealed that V2O5 was reduced to lower oxides upon laser treatment. Furthermore, the presence of reduced valence states of vanadium has been detected through XPS in vanadium-containing solids such as V2O5/P2O5 glass, thin films prepared separately from V2O5 powder and the glass.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

The optical absorption spectra of fine grained polycrystalline thin films of lithium tungsten bronze are reported. The results are similar to the previously reported data for hydrogen and sodium tungsten bronzes: pointing to the secondary importance of the nature of the guest atom. The visible blue color band, peaking in the near infrared, is attributed to electron transitions from the conduction band to higher lying states. The absence of free carrier absorption in material, which is very small grained polycrystalline material (tens of nm and less) is tentatively attributed to a modified electron–phonon interaction. The main gap of the bronze, which is indirect, is effectively increased by electron filling of the conduction band, this effect is overwhelmed by bandgap shifts associated with crystallographic changes, which are a function of the guest atom type and concentration.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Transmission and reflection spectra in the range of 0.5–4.1 eV have been obtained for HxWO3 polycrystalline thin films of 5-nm mean grain size. The composition range x=0–0.16 has been investigated. The measurements were refined to give the absorption coefficient and other optical parameters versus photon energy. The data have been interpreted in terms of the interband transition model due to Green and Travlos [Philos. Mag. B 51, 501 (1985)]. It is noted that main gap changes because of changes in crystal structure, and there is a sensitivity of the main gap value to grain size which may have its origins in quantum confinement effects.

Electronic Resource

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

Using multilayer linear polarizers, we have characterized the polarization state of radiation from bend-magnet beamline 9.3.2 at the Advanced Light Source as a function of vertical opening angle at photon energies of 367 and 722 eV. Both a fine slit and a coarse semi-aperture were stepped across the beam to accept different portions of the vertical radiation fan. Polarimetry yields the degree of linear polarization directly and the degree of circular polarization indirectly assuming an immeasurably small amount of unpolarized radiation based on the close agreement of the theoretical and experimental results for linear polarization. The results are in good agreement with theoretical calculations, with departures from theory resulting from uncertainty in the effective aperture of the measured beam. The narrow 0.037-mrad aperture on the orbit plane transmits a beam whose degree of linear polarization exceeds 0.99 at these energies. The wide semi-aperture blocking the beam from above and below transmits a beam with a maximum figure of merit, given by the square root of flux times the degree of circular polarization, when the aperture edge is on the orbit plane thus blocking only half of the total available flux. © 1996 American Institute of Physics.

Electronic Resource

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

Bending magnet beamline 9.3.2 at the Advanced Light Source (ALS) was designed for high resolution spectroscopy with the capability for delivering circularly polarized light in the soft x-ray energy region using three gratings. The monochromator is a fixed included-angle spherical grating monochromator (SGM) and was originally used at SSRL as a prototype for later insertion-device-based monochromators for the ALS. For operation at the ALS, the toroidal pre-mirror used at SSRL was replaced by a horizontally focusing and a vertically focusing mirror in the Kirkpatrick-Baez configuration. Circularly polarized radiation is obtained by inserting a water-cooled movable aperture in front of the vertically focusing mirror to allow selecting the beam either above or below the horizontal plane. To maintain a stable beam intensity through the entrance slit, the photocurrent signals from the upper and lower jaws of the entrance slit are utilized to set a feedback loop with the vertically deflecting mirror piezoelectric drive. The beamline end station has a movable platform that accommodates two experimental chambers enabling the synchrotron radiation to be directed to either one of the two experimental chambers without breaking the vacuum. © 1996 American Institute of Physics.

Electronic Resource

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

A resolving power, E/ΔE, of ≥13 000 has been achieved with the modified 6 m/160° toroidal grating monochromator (TGM) installed on Beam Line 8-1 at the Stanford Synchrotron Radiation Laboratory. The resolving power of the TGM was increased by replacing the entrance and exit slits with high-precision slits, masking the horizontal part (short radius) of the grating, and improving the TGM scanning mechanisms. To determine the performance of the monochromator, we measured the dependences of resolution and photon flux on the entrance- and exit-slit widths, the exit-slit position, and the masking of the grating. The monochromator resolution in the energy range of 25–65 eV was derived from photoionization measurements of extremely narrow core-excitation resonances in He and Ne. With 10-μm vertical entrance- and exit-slit widths and 32% mask opening of the grating, the monochromator has a resolution (full-width at half maximum) of 5.0±0.7 meV at a photon energy of 64.5 eV and a flux of 2×107 photons/s/100 mA. The results suggest a simple procedure for converting a TGM with moderate resolution into a high-resolution monochromator with a moderate reduction in photon flux due to masking the grating, beyond the reduction attributable to the slit widths.

Electronic Resource

1524-475X

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Hypothesis:  Both hypoxia and lactate independently induce VEGF synthesis. However, an adequate supply of oxygen is required for new vessels to mature.Materials and Methods:  We used in vivo matrigel (growth factor reduced) angiogenesis assay and Swiss Webster mice n = 36 (3 groups of 12 with 6 control and 6 experimental in each). Each mouse received a 1 ml subcutaneous matrigel injection. Matrigel solidifies into a gel implant when injected subcutaneously. Control injections/implants were matrigel with no added substance and experimental implants were matrigel supplemented with 30 mgs of crushed lactate polymer or PL (poly DL-Lactide-co-Glycolide 50:50; av. mol.wt. 50–75,000 kilo Daltons). The first group of mice was maintained in 12–14% oxygen, the second group in 21% oxygen, and the third group in 50–52% oxygen continuously for 11 days, at which time the implants were harvested, fixed, sectioned, and stained with Mason’s Trichrome to identify new vessels and collagen.Results:  1. 13% oxygen control: Half showed new blood vessels with thin or incomplete walls and hemorrhages. Few collagen fibers2. 13% oxygen with PL: same as above3. 21% oxygen control: none showed new blood vessels/collagen fibers4. 21% oxygen with PL: five out of six showed new blood vessels. Almost all were mature, with complete walls, collagen fibers, and no hemorrhages5. 51% oxygen control: None showed new blood vessels/collagen fibers6. 51% oxygen with PL: all six developed new vessels with some hemorrhage seen in two out of six. Collagen fibers presentNote: matrigel contains collagen and stained a pale blue, collagen fibers were seen as dark blue, endothelial cells and RBCs as dark red and red. All blood vessels contained RBCs.Conclusions:  Hypoxia and lactate induce VEGF. However, hypoxia limits vascular growth by inhibiting collagen deposition. The largest and most mature new vessels result from a combination of oxygen and lactate.

Electronic Resource

1524-475X

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Introduction: Vascular Endothelial Growth Factor (VEGF) mediated angiogenesis plays a key role in wound healing. Insulin-like Growth Factor I (IGF-I) has been reported to be angiogenic. However, the mechanism is not known. Recently, a link between transcriptional activity and inhibition of poly(ADP-Ribose)polymerase (PARP) has been reported. We investigated whether IGF-I increases VEGF expression and whether this effect is regulated by the inhibition of PARP. Material and methods: Subconfluent monolayers of human umbilical vein cells were cultured and serum starved. Cultures were treated with Long-R3-IGF-I for 20 h. VEGF in the supernatant was measured by ELISA and lactate by a lactate analyser. PARP activity was assessed by measuring the incorporation of 14C-radiolabeled NAD+. All experiments were performed in triplicate. Results are given as percent change compared to control ± SD; p 〈 0.05 calculated by Student‘s t-test was considered significant. Results: IGF-I increased both VEGF (20 ± 10%, 50 ± 16%(p = 0.01) and 79 ± 13%(p = 0.0003)) and lactate production (12 ± 11%, 20 ± 12% and 48 ± 16%(p = 0.01)) in a dose dependent manner (25, 50 and 100 ng/ml). Blocking glucose utilization by 2-desoxyglucose, decreased lactate by 70 ± 11%(p = 0.0001), but not VEGF expression. Inhibitors of MAP-kinase (PD 98059) and Proteinkinase C (Staurosporine) reduced the IGF-I effect on VEGF expression by 40 ± 6%(p = 0.0003) and 30 ± 7%(p = 0.01). 3-Aminobenzamide and nicotinamide alone, inhibitors of PARP, stimulated VEGF production by 66 ± 5%(p = 0.0003) and 32 ± 8%(p = 0.002), respectively. IGF-I inhibited PARP by 44 ± 3%(p = 0.01). Conclusion: IGF-I enhances VEGF protein expression in endothelial cells. This is mediated through signal transduction and by inhibition of PARP.

Electronic Resource

1524-475X

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

INTRODUCTION: High concentrations of lactate approx. 10 mM are characteristic of wound healing. We have previously shown that lactate instigates release of VEGF from macrophages and endothelial cells. Our present study uses an in vivo murine Matrigel model to study how lactate enhances vascular development and repair.METHODS: Matrigel is a reconstituted basement membrane complex, a liquid at 4 degree C. When injected subcutaneously, it reconstitutes as a gel. 30 mgs of finely divided polylactate polymer (DL-lactide-co-glycolide) was mixed with 1cc of Matrigel, and 2 injections were made into the dorsum of each of 60 (average 7/group), 6-month-old Swiss Webster mice. The gel implants were harvested at 3, 6, 9, 11 and 16 days post injection, and were fixed in buffered formalin or frozen. Cell migration and vascular development were assessed using H&E, anti-CD31 and anti-MAC3 antibody stainings for leukocytes, fibroblasts, endothelial cells, and macrophages. Cells and vessels were quantified microscopically.RESULTS: Control implants (without polylactate) developed little or no inflammation or angiogenesis. Polylactated implants developed highly significant number of endothelial cells and recognizable vessels at 6 and 9 days. At 11 and 16 days, sizeable vessels with surrounding connective tissue were found. Though a moderate inflammation occurred in the lactate groups, no foreign body reaction was seen. Larger implants of high molecular weight instigated little inflammation and few vessels.CONCLUSION: Slowly released lactate leads to the formation of new vessels. Our results provide support for further clinical applications of lactate polymer in wounds.NIH/NIGMS Trauma Training Grant

Electronic Resource

1365-2044

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Electronic Resource

1359-0189

Air borne contamination ; Environmental contamination ; Polymeric track detectors ; Radon ; Specific gravity

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Electrical Engineering, Measurement and Control Technology

Physics

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] The superconducting gap—an energy scale tied to the superconducting phenomena—opens on the Fermi surface at the superconducting transition temperature (Tc) in conventional BCS superconductors. In underdoped high-Tc superconducting copper oxides, a ...

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] Coupling between electrons and phonons (lattice vibrations) drives the formation of the electron pairs responsible for conventional superconductivity. The lack of direct evidence for electron–phonon coupling in the electron dynamics of the high-transition-temperature superconductors has ...

Electronic Resource

0038-1098

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Physics

Electronic Resource