Athermal all-polymer arrayed-waveguide grating multiplexer

An athermal arrayed-waveguide grating (AWG) multiplexer relying on an all-polymer approach is reported. The all-polymer AWG consisting of polymer waveguides fabricated on a polymer substrate exhibits excellent performance. By properly adjusting the coefficient of thermal expansion of the polymer substrate, athermal and polarisation-independent AWG devices featuring a wavelength shift of less than ±0.05 nm in the 25-65°C temperature range could be demonstrated     

Catalytic oxidation of 1,2-dichlorobenzene over ABO3-type perovskites

Several ABO₃-type perovskite oxides (A = La, Y, Nd or Gd; B = Fe, Mn, Cr or Co) have been investigated as catalysts for the oxidation of 1,2-dichlorobenzene (o-DCB), a model compound for the highly toxic polychlorinated dibenzodioxins. Initial transient and steady state activity measurements were conducted with all catalysts in the absence and presence of water. Perovskites containing Cr in the B-site were more active than perovskites containing other transition metals, with YCrO₃ being the most active catalyst among the different systems studied. Furthermore, YCrO₃ did not show any loss of its initial activity after several hours on stream. Other perovskites lost 10–20% of their initial activity within the first 5–10 h on stream. This loss was associated with a corresponding loss in BET surface area. With the exception of LaCoO₃, all perovskites retained their crystalline structure upon exposure to o-DCB under reaction conditions. LaCoO₃ was converted to LaOCl and Co₃O₄. The presence of water appeared to enhance the catalytic activity of some perovskites. This effect can be attributed to a faster removal of Cl⁻ ions from the catalyst surface via their reaction with water.     

Ultrafast pulse generation in photoconductive switches

Carrier and field dynamics in photoconductive switches are investigated by electrooptic sampling and voltage-dependent reflectivity measurements. We show that the nonuniform field distribution due to the two-dimensional nature of coplanar photoconductive switches, in combination with the large difference in the mobilities of holes and electrons, determine the pronounced polarity dependence. Our measurements indicate that the pulse generation mechanism is a rapid voltage breakdown across the photoconductive switch and not a local field breakdown     

Nephroprotection by long-term ACE inhibition with ramipril in spontaneously hypertensive stroke prone rats

BACKGROUND: The effect of life-long treatment with the ACE inhibitor ramipril on hypertension-induced histological changes in the kidney was tested in stroke-prone spontaneously hypertensive rats (SHR-SP). METHODS: One-month-old pre-hypertensive SHR-SP were randomized into three groups of 45 animals each, and exposed via drinking water for their lifetime to a dose of: 1 mg.kg-1.d-1 ramipril (antihypertensive dose, HRA); 10 micrograms.kg-1.d-1 slight dose of ramipril (non-antihypertensive dose, LRA); or placebo. Histological and biochemical assessments were conducted after 15 months in ten rats each, when about 80% of the placebo group had died. RESULTS: Kidneys from placebo treated SHR-SP showed pronounced arterial wall hypertrophy and sclerosis, arterial fibrinoid necrosis, glomerulopathy and tubular interstitial injury that were, in concert with normalized blood pressure, completely prevented by HRA treatment. LRA treatment did not affect any blood pressure increase, and also attenuated the development of arterial wall hypertrophy, sclerosis and arterial fibrinoid necrosis, though to a minor extent only, but did not change glomerular and tubulointerstitial degeneration. These effects of ramipril were associated with a dose-dependent inhibition of plasma and renal tissue ACE activities as well as lower serum concentrations of creatinine, but there were no changes in serum potassium. CONCLUSIONS: Life-long HRA-induced ACE inhibition protects against hypertension-induced renal damages in SHR-SP. This is associated with a doubling of the lifespan in these animals.     

Plasma volume expansion with oral fluids in hypohydrated men at rest and during exercise

A case of malignant fibrous histiocytoma (MFH) in a 29-year-old man was reported. CT scans revealed an iso density mass which was homogeneously enhanced by contrast medium. MRI demonstrated that the right frontal tumor showed slight low signal intensity in T1-weighted image, and iso signal intensity in T2-weighted image. Gadolinium-enhanced T1-weighted image showed a homogeneously enhanced multinodular tumor. Right carotid angiogram revealed a tumor stain fed by the precentral artery. On operation, en-bloc resection was performed successfully. Postoperatively, local irradiation of 60Gy was performed. Microscopically, fibroblast-like cells arranged in storiform pattern were observed, and bizarre multinucleated giant cells were also observed. Ki-67 labelling index was 54%. We considered the tumor was a MFH and arose from an intracerebral mesenchymal tissue. We reviewed some literature and briefly discussed clinicopathological features and therapy of intracranial MFH.     

Monitoring of toxic compounds in air using a handheld rectilinear ion trap mass spectrometer

A miniature, handheld mass spectrometer, based on the rectilinear ion trap mass analyzer, has been applied to air monitoring for traces of toxic compounds. The instrument is battery-operated, hand-portable, and rugged. We anticipate its use in public safety, industrial hygiene, and environmental monitoring. Gaseous samples of nine toxic industrial compounds, phosgene, ethylene oxide, sulfur dioxide, acrylonitrile, cyanogen chloride, hydrogen cyanide, acrolein, formaldehyde, and ethyl parathion, were tested. A sorption trap inlet was constructed to serve as the interface between atmosphere and the vacuum chamber of the mass spectrometer. After selective collection of analytes on the sorbent bed, the sorbent tube was evacuated and then heated to desorb analyte into the instrument. Sampling, detection, identification, and quantitation of all compounds were readily achieved in times of less than 2 min, with detection limits ranging from 800 parts per trillion to 3 parts per million depending on the analyte. For all but one analyte, detection limits were well below (3.5-130 times below) permissible exposure limits. A linear dynamic range of 1-2 orders of magnitude was obtained over the concentration ranges studied (sub-ppbv to ppmv) for all analytes.