Design of fiber Bragg grating-based Fabry–Perot sensor for simultaneous measurement of humidity and temperature

A new sensor for simultaneous measurement of humidity and temperature is proposed. The sensor consists of Fabry–Perot cavity formed by two identical uniform fiber Bragg gratings. To make the cavity serves as humidity sensor, moisture sensitive polymer, which is polyimide, is coated on the FBG and on the cavity with different thickness. When the sensor is exposed to the relative humidity change, the polyimide will expand and stretch the fiber and induces strain on the FBG and on the cavity. The induced strain alters the grating period, cavity length and effective refractive index of fiber. The simulation results show that the humidity sensitivity and thermal sensitivity are 1.92 pm/%RH and 8.87 pm/°C, respectively, for polyimide coating thickness of 10 μm on the FBG and 15 μm on the cavity.     

Efficient enantioselective synthesis of tetramic acids and lactams from threonine

Regioselective Dieckmann and aldol cyclisations using an N-acyloxazolidine derived from threonine give substituted tetramic acids and pyroglutamates in high yield and enantioselectivity. These are easily deprotected under mild conditions to give products, some of which exhibit antibacterial activity.     

Numerical investigation of natural convection inside an inclined parallel‐walled channel

Steady two‐dimensional natural convection in an inclined parallel‐walled channel was investigated numerically. The full elliptic forms of conservation equations were solved together and the velocity vectors, temperature contours and local and average Nusselt number distribution were obtained. The comparisons of local and average Nusselt number with published experimental and numerical results indicate very good agreement. Results are presented for a single aspect ratio, L/b=24, over the range of Rayleigh number of 3–1000 and angle of inclination 0–90°. The results indicate that the overall channel average Nusselt number is reduced as the inclination angle is increased. Significant reductions in the overall Nusselt number are exhibited at high angle of channel inclination. Copyright © 2005 John Wiley & Sons, Ltd.     

“0.75 eV killer centre” in red-emitting GaP LEDs

Dark transient capacitance measurements have been used to investigate the deeplevel content of red GaP LEDs. Thermal emission rate data is obtained and the 0.75 eV “killer” centre is identified from the signature.     

Studies on tungstate gels

Summary The magnetic susceptibilities of certain vanadium pentoxide systems supported by kieselgur have been determined in the temperature interval 30° to 400° C. The plot of reciprocal susceptibility against temperature for all the systems studied indicates sudden deflections at temperatures which are about 150° lower than those of optimum catalytic activity. It has been suggested that these points may mark the temperatures of commencement of structural changes which may be responsible for the activity of these catalysts.

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Zusammenfassung Die magnetische Susceptibilit?t gewisser Vanadium-Pentoxyd-Systeme mit Kieselgur als Tr?ger wurden im Temperaturintervall zwischen 30 und 400° C bestimmt. Die Auftragung der reziproken Susceptibilit?t gegen die Temperatur zeigt für alle untersuchten Systeme pl?tzliche Knicke bei Temperaturen, die etwa 150° niedriger liegen als die optimale katalytische Aktivit?t. Es wird vermutet, da? diese Knickpunkte die Temperaturen des Beginns von Struktur?nderungen zeigen, die für die Aktivit?t dieser Katalysatoren verantwortlich sind.

     

trans-cis Photoisomerization of a photoactive yellow protein model chromophore in crystalline phase

We have studied the photoinduced trans/cis isomerization of the protonated form of p-hydroxycinnamic thiophenyl ester, a model chromophore of the photoactive yellow protein (PYP), in crystalline phase, by both fluorescence and infrared spectroscopies. The conversion from trans to cis configuration is revealed by a shift of the fluorescence peak and by inspection of the infrared maker bands. The crystal packing apparently stabilizes the cis photoproduct, suggesting different environmental effects from the solvent molecules for this model chromophore in liquid solutions or from the amino acid residues for the PYP chromophore.     

Differential functional theory and molecular docking studies of newly synthesized carbamates

Four new carbamates (RZ1–RZ4) were synthesized from different amine moieties through reported methods. The reaction was monitored using thin layer chromatography and characterization was done using m.p., fourier‐transform infrared spectroscopy (FTIR), and X‐ray diffraction (XRD) techniques. Density functional theory (DFT) studies were carried out using Gaussian 09 software to compare the theoretical and practical parameters of the synthesized compounds. Highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) were also drawn to calculate the energy difference between orbitals. In‐vitro enzyme inhibition potential against acetylcholine esterase (AChE), butyrylcholine esterase (BChE), and protease was checked through standard protocols that suggested moderate inhibition against selected enzymes. Docking studies were also carried out, which depicted that these compounds have ability to bind on the active site of AChE and BChE.     

Bejan flow visualization of free convection in a Jeffrey fluid from a semi-infinite vertical cylinder

Journal of Thermal Analysis and Calorimetry - This article studies the pattern of heat lines in free convection non-Newtonian flow from a semi-infinite vertical cylinder via Bejan’s heat...     

Effect of Trichoderma reesei Proteinases on the Affinity of an Inorganic-Binding Peptide

An inorganic-binding peptide sequence with high affinity to silica-containing materials was fused to a glycoside hydrolase GH26 mannanase, ManA, from the extremely thermophilic bacterium Dictyoglomus thermophilum. The resulting recombinant enzyme produced in Escherichia coli, ManA-Linker, displayed high binding affinity towards synthetic zeolite while retaining its catalytic activity at 80 °C. ManA-Linker was able to bind to the zeolite at different pH levels, indicating a true pH-independent binding. However, complete degradation of the peptide linker was observed when the recombinant ManA-Linker was exposed to the supernatant from the filamentous fungus Trichoderma reesei. This degradation was caused by extracellular proteinases produced by T. reesei during its growth phase. Several derivatives of ManA-Linker were designed and expressed in E. coli. All the derivatives carrying a single sequence of the linker were still susceptible to T. reesei proteinase degradation. Complete substitution of the linker sequence by (GGGGS)₁₆ resulted in a proteinase-resistant ManA derivative, ManA-Linker-(GGGGS)₁₆, which was able to bind to zeolite in a pH-dependent manner.