Synthetic and biological studies on a cyclopolypeptide of plant origin

Objective： A natural cyclic peptide previously isolated from Citrus medica was synthesized by coupling of tetrapeptide units Boc-Leu-Pro-Trp-Leu-OMe and Boc-Ile-Ala-Ala-Gly-OMe after proper deprotection at carboxyl and amino terminals followed by cyclization of linear octapeptide segment. Methods： Solution phase technique was adopted for the synthesis of cyclooctapeptide-sarcodactylamide. Required tetrapeptide units were prepared by coupling of Boc-protected dipeptides viz. Boc-Leu-Pro-OH and Boc-Ile-Ala-OH with respective dipeptide methyl esters Trp-Leu-OMe and Ala-Gly-OMe. Cyclization of linear octapeptide unit was done by p-nitrophenyl ester method. The structure of synthesized cyclopolypeptide was elucidated by FTIR, ^1H NMR, ^13C NMR, FABMS spectral data and elemental analysis. The newly synthesized peptide was evaluated for dif- ferent pharmacological activities including antimicrobial, anthelmintic and cytotoxic activities. Results： Synthesis of sarcodactylamide was accomplished with 〉78% yield utilizing dicyclohexylcarbodiimide （DCC） as coupling agent. Newly synthesized peptide possessed potent cytotoxic activity against Dalton＇s lymphoma ascites （DLA） and Ehrlich＇s ascites carcinoma （EAC） cell lines, in addition to moderate anthelmintic activity against earthworms Megascoplex konkanensis, Pontoscotex corethruses and Eudrilus sp. Moreover, cyclopolypeptide displayed good antimicrobial activity against pathogenic fungi Candida albicans and Gram-negative bacteria Pseudomonas aeruginosa, in comparison to standard drugs griseofulvin and ciprofloxacin. Conclusion： Solution phase technique employing DCC and triethylamine （TEA） as base proved to be effective for the synthesis of natural cyclooctapeptide. N-methyl morpholine （NMM） was found to be a better base for the cyclization of linear octapeptide unit in comparison to TEA and pyridine.     

Strong coupling of a single photon to a superconducting qubit using circuit quantum electrodynamics

The interaction of matter and light is one of the fundamental processes occurring in nature, and its most elementary form is realized when a single atom interacts with a single photon. Reaching this regime has been a major focus of research in atomic physics and quantum optics for several decades and has generated the field of cavity quantum electrodynamics. Here we perform an experiment in which a superconducting two-level system, playing the role of an artificial atom, is coupled to an on-chip cavity consisting of a superconducting transmission line resonator. We show that the strong coupling regime can be attained in a solid-state system, and we experimentally observe the coherent interaction of a superconducting two-level system with a single microwave photon. The concept of circuit quantum electrodynamics opens many new possibilities for studying the strong interaction of light and matter. This system can also be exploited for quantum information processing and quantum communication and may lead to new approaches for single photon generation and detection.     

Mapping multiple features in the population response of visual cortex

Stimulus features such as edge orientation, motion direction and spatial frequency are thought to be encoded in the primary visual cortex by overlapping feature maps arranged so that the location of neurons activated by a particular combination of stimulus features can be predicted from the intersections of these maps. This view is based on the use of grating stimuli, which limit the range of stimulus combinations that can be examined. We used optical imaging of intrinsic signals in ferrets to assess patterns of population activity evoked by the motion of a texture (a field of iso-oriented bars). Here we show that the same neural population can be activated by multiple combinations of orientation, length, motion axis and speed. Rather than reflecting the intersection of multiple maps, our results indicate that population activity in primary visual cortex is better described as a single map of spatiotemporal energy.     

运动的连续平直面上边界层流之解的渐近性质

Falkner-Skan方程描述磁场中连续平直面上不可压缩粘性流的边界层流,本文研究此方程初值问题之解的渐近性质。     

A preliminary report onγ-irradiated protein-dye complexes

Summary In spectral studies of -irradiated protein-dye complexes, influences of concentrations of the components and changes in dye character are mainly noted.I thank Mr K. L. Bhattacharya, Officer in Charge of this Centre for encouragement, Prof. K. M. Khanna of Birla Institute of Technology, Ranchi, for discussion and the authorities of Chittaranjan Cancer Hospital, Calcutta, for irradiation facilities.     

Effects of γ-rays on DNA-cholesterol complex

Summary Effects of -rays on the DNA-cholesterol complex have been studied. Radiation-induced changes are found and compared with those on DNA-dye or drug complexes.Acknowledgment. Thanks are due to P. K. Roy, K. L. Bhattacharya and K. M. Khanna (Department of Physics, Birla Institute of Technology, Ranchi) for helpful discussions and the Chittaranjan Cancer Hospital (Calcutta) for irradiation facilities.     

Development of a new coated electrode with low nickel content for welding ductile iron and its response to austempering

Coated Electrodes with small amounts of nickel were developed for welding ductile iron (DI) and conversion of the same into austempered ductile iron (ADI) after austempering. Among six electrodes, Trials 3 and 4 were selected for establishing crack-free weld deposits via preheating and post-weld heat treatment. Austenitization was performed at 900℃ for 2 h and austempering at 300 or 350℃ for three different holding times to observe the results of austempering with respect to the microstructure, hardness, and austempering kinetics of the samples. The microstructures of the weld deposits showed needle-like bainitic ferrite with small amounts of retained austenite when treated at 300℃ and feathery bainitic ferrite with large amounts of retainedaustenite when treated at 350℃. The electrode labeled with Trial 3 revealed greater austenite contents than that labeled with Trial 4 when treated with a 2 h holding time regardless of the austempering temperature applied. The transformation rate of the bainitic ferrite of Trial 3 was relatively higher than that of Trial 4 and showed a lower rate constant, leading to a higher diffusion rate of carbon in austenite.     

Synthesis and characterization of copper foams through a powder metallurgy route using a compressible and lubricant space-holder material

In the present work, a compressible and lubricating space-holder material commonly known as “acrawax” was used to process Cu foams with various pore sizes and various porosities. The foams were processed without using binders to avoid contamination of their metal matrices. The lubricant space-holder material was found to facilitate more uniform flow and distribution of metal powder around the surface of the space holder. In addition, the use of acrawax as a space-holder material yielded considerably dense cell walls, which are an essential prerequisite for better material properties. The foams processed with a smaller-sized space holder were found to exhibit better electrical and mechanical properties than those processed with a coarser-sized space holder. The isotropic pore shape, uniform pore distribution throughout the metal matrix, and uniform cell wall thickness were found to enhance the properties pertaining to fine-pore foam samples. The processed foams exhibit properties similar to those of the foams processed through the lost-carbonate sintering process.     

Karkata,a new genus of gecarcinucid freshwater crab with two new species,and four new species of Pilarta Bahir and Yeo, 2007 and Cylindrotelphusa Alcock, 1909 (Decapoda: Brachyura) from Kerala,India

A new genus of freshwater crab, Karkata gen. nov., with two species, K. ghanarakta sp. nov. (type species) and K. kusumbha sp. nov., and two new species each of Pilarta Bahir and Yeo, 2007 (P. aroma sp. nov. and P. punctatissima sp. nov.) and Cylindrotelphusa Alcock, 1909 (C. breviphallus sp. nov. and C. longiphallus sp. nov.), are described from Kerala, India. Additionally, C. granulata (Pillai, 1951) comb. et stat. nov. is recognised as a distinct species. Karkata gen. nov. is distinguished from other Indian gecarcinucid genera by a suite of carapace and gonopod characters, including a moderately arched, smooth carapace, the presence of a prominent suture between male thoracic sternites 2, 3 and 3, 4, the absence of a flagellum on the third maxilliped exopod, a very short terminal segment of the male first gonopod (G1), and a short distal segment of the male second gonopod (G2). Karkata ghanarakta sp. nov. is differentiated from K. kusumbha sp. nov. by the shape of the G1 subterminal segment and its live colouration. Pilarta punctatissima sp. nov. is distinct among the congeners mainly by its densely punctate carapace, densely setose anterolateral and posterolateral margins of the carapace, stouter G1 terminal segment, and relatively long G2 distal segment whereas P. aroma sp. nov. can be separated from P. anuka Bahir and Yeo, 2007 by its relatively smooth carapace, deep H-shaped groove, relatively long G1 terminal segment, and almost straight outer margins of the G1 terminal and subterminal segments. Cylindrotelphusa breviphallus sp. nov. is differentiated from C. longiphallus sp. nov. and C. steniops (Alcock, 1909) by its stout G1, with a stout, short terminal segment. Cylindrotelphusa longiphallus sp. nov. is distinguished from the congeners by its shallow, narrow cervical grooves and relatively slender ambulatory legs. An identification key to the species of Karkata, Pilarta and Cylindrotelphusa is provided.

http://zoobank.org/urn:lsid:zoobank.org:pub:AB9B01DA-B23F-4AC2-9349-75ADDBBBF707