Adhesion and growth of electrically-active cortical neurons on polyethyleimine patterns microprinted on PEO-PPO-PEO triblockcopolymer-coated hydrophobic surfaces

This paper describes the adhesion and growth of dissociated cortical neurons on chemically patterned surfaces over a time period of 30 days. The presence of neurons was demonstrated by measurement of spontaneous bioelectrical activity on a micropatterned multielectrode array. Chemical patterns were prepared with a combination of neurophobic layers of polyethylenoxide-polypropylenoxide-polyethylenoxide (PEO-PPO-PEO) triblockcopolymers adsorbed onto hydrophobic surfaces and neurophilic microprinted tracks of polyethylenimine (PEI). Results showed that commercially available PEO-PPO-PEO triblockcopolymers F108 and F127 (Synperonics, ICI) significantly reduced the adhesion of neuronal tissue when adsorbed on hydrophobic Polyimide (PI) and Fluorocarbon (FC) surfaces over a time period of eight days. In general, both F108- and F127-coated PI displayed equal or better neurophobic background properties after 30 days. Viability of neuronal tissue after 30 days on PEI microprinted F108- and F127-coated PI was comparable with relatively high viability factors between 0.9 and 1 (scale from 0 to 1). Summarizing, the strategy to combine the neurophobic adsorbed triblock-copolymers F108 and F127 onto hydrophobic surfaces with neurophilic microprinted PEI resulted in relatively long-term neuronal pattern preservation with high numbers of viable neurons present after 30 days

Detailed comparison of injection-seeded and self-seeded performance of a 1060nm gain-switched Fabry-Perot laser diode

We investigate and compare the performance of a gain-switched picosecond Fabry-Perot laser diode operated at 1.06 µm under both injection- and self-seeded conditions. Our experiments show that comparable performance can be obtained for both modes of operation, with the self-seeding arrangement offering overall benefits in terms of reduced system complexity and cost, providing the associated quantization of available pulse repetition rate can be tolerated

High quality 5ps pulse generation at 10 Gbit/s using a fibre Bragg grating compensated gain-switched laser diode

A fibre Bragg grating is designed to spectrally filter and perfectly compensate the chirped pulses from a gain-switched laser diode. This design is based on the exact characterisation of the intensity and phase profiles using an electro-optic pulse characterisation technique. This results in a compact pulse source that should produce high quality 5 ps duration pulses with a 50 dB pedestal suppression

Editorial

We use a linear FROG technique based on electro-optic modulation to fully characterise for the first time pulses from a 1.06 µm FP laser diode and design a grating to provide optimum pulse compression

On the modelling of biological effects on morphology in estuaries and seas

Morphological modelling aims to explain and predict the changes in rivers, seas and estuaries due to these interaction. In recent history, a lot of progress has been made, especially with stability analysis approaches. However, so far only the physical interactions have been taken into account. It is known however, that biological factors are important to the dynamics of the water systems. In this paper a first step is made in the inclusion of biology into the morphodynamic models. This inclusion is based on the effect that benthic organisms have on the erodibility of the bed. This can easily be included by a change of the critical bed shear stress. These changes in the critical bed shear stress then influence the morphology. This idea has been applied to two cases. The results of the first case indicate that this approach can reproduce the influence of benthic organisms on the mud content of the bed in estuaries. The second case shows that even low numbers of organisms can influence the characteristics of large bed forms

Study on the Changes in Common Laboratory Parameters in Dengue Patients with Secondary Bacterial Infection

Secondary bacterial infection can adversely affect the clinical course of primary viral infection in dengue fever. Time consuming microbiological culture confirmations and false negative culture results delay the timely initiation of antibiotics. The objective of this study was to describe the variation in the common laboratory parameters during the illness, identify criteria that may predict secondary bacterial infection before microbial culture confirmation, identify the common organisms causing secondary bacterial infections and their antibiotic sensitivity patterns. A retrospective case-control study was carried out at the Dengue Management Unit of the National Institute of Infectious Diseases, Sri Lanka. Patients treated with antibiotics upon suspicion or culture confirmation of secondary bacterial infections and patients not treated with antibiotics were selected for the study. Total WBC count, absolute neutrophil count, platelet count, HCT (Hematocrit), CRP (C Reactive Protein) and average body temperature were recorded. Independent sample t-test was used to analyze the data. Study results showed that most positive microbial cultures were detected on the 6th and 7th days of illness. Staphylococcus, Streptococcus, and non-speciated Gram-positive cocci were the commonly isolated organisms. Patients with confirmed secondary bacterial infection had significantly higher neutrophil count (3.32±0.35x103/μL, p<0.05) and lower platelet counts (49.33±7.66x103/μL, p<0.05) on the 6th and 5th day of illness respectively. The average body temperature was significantly higher in the study group than the control from the fever day 3 onwards (p<0.05). The study subjects were more likely to have significantly lower HCT values (38.62±1.12%, p<0.05) than their controls on the third and fourth days of fever. Overall, the present study suggests that bacterial co-infection increases the mortality rate in dengue patients. The variation in absolute neutrophil count, platelet count, and body temperature pattern compared to the illness day can be used along for early prediction of secondary bacterial infection. Keywords:  dengue, bacterial infection, antibiotics, platelet count, HC

Experimental and molecular docking studies on DNA binding interaction of derivative of N-Arylhydroxamic Acid

Binding affinity towards DNA for small molecules such as derivatives of Hydroxamic acids is very important in the development of new therapeuticreagents The binding interaction of N- (o-chloro) phenyl benzoh ydroxamicacid (N-(o-chloro)PBHA) with Ct-DNA was measured by four methods, (i) UV absorption, (ii) fluorescence emission, (iii) viscosity and (iv)molecular docking. It showed that N-(o-chloro) PBHA-DNA complex has less absorption intensity than compound only. Significant enhancement of fluorescence intensity was observed for the N-(o-chloro) PBHA-DNA complex. The values of binding constant, Kb, is 7.87x 10-3 and Stern Volmer constant Ksv is 3.0x10-3 ng-1 μl were obtained by UV absorption and fluorescence spectral methods, respectively. The binding interaction trend was further confirmed by viscosity on–Ct-DNA complex which shows the increase in viscosity. The molecular docking of N-(o-chloro) PBHA with the DNA showed the groove binding nature. This observation further confirmed and supplemented the experimental results. The study revealed that the hydroxamic acid derivative seems to have promising anti-cancer drug like nature