Optimizing the Sensing Efficiency of Plasmonic Based Gas Sensor

Plasmonics - This paper investigates the behavior of the surface plasmon polaritons (SPPs) on dielectric-metal interface using Ag thin film on glass substrate. The Kretschman configuration, which...     

Tumor Necrosis Factor -α, Interleukin-10, Intercellular and Vascular Adhesion Molecules Are Possible Biomarkers of Disease Severity in Complicated Plasmodium vivax Isolates from Pakistan

Background

Cytokine-mediated endothelial activation pathway is a known mechanism of pathogenesis employed by Plasmodium falciparum to induce severe disease symptoms in human host. Though considered benign, complicated cases of Plasmodium vivax are being reported worldwide and from Pakistan. It has been hypothesized that P.vivax utilizes similar mechanism of pathogenesis, as that of P.falciparum for manifestations of severe malaria. Therefore, the main objective of this study was to characterize the role of cytokines and endothelial activation markers in complicated Plasmodium vivax isolates from Pakistan.

Methods and Principle Findings

A case control study using plasma samples from well-characterized groups suffering from P.vivax infection including uncomplicated cases (n=100), complicated cases (n=82) and healthy controls (n=100) were investigated. Base line levels of Tumor necrosis factor-α (TNF-α), Interleukin-6 (IL-6), Interleukin-10 (IL-10), Intercellular adhesion molecule-1 (ICAM-1), Vascular adhesion molecule-1(VCAM-1) and E-selectin were measured by ELISA. Correlation of cytokines and endothelial activation markers was done using Spearman’s correlation analysis. Furthermore, significance of these biomarkers as indicators of disease severity was also analyzed. The results showed that TNF-α, IL-10, ICAM-1and VCAM-1 were 3-fold, 3.7 fold and 2 fold increased between uncomplicated and complicated cases. Comparison of healthy controls with uncomplicated cases showed no significant difference in TNF-α concentrations while IL-6, IL-10, ICAM-1, VCAM-1 and E-selectin were found to be elevated respectively. In addition, significant positive correlation was observed between TNF-α and IL-10/ ICAM-1, IL-6 and IL-10, ICAM-1 and VCAM-1.A Receiver operating curve (ROC) was generated which showed that TNF-α, IL-10, ICAM-1 and VCAM-1 were the best individual predictors of complicated P.vivax malaria.

Conclusion

The results suggest that though endothelial adhesion molecules are inducible by pro-inflammatory cytokine TNF-α, however, cytokine-mediated endothelial activation pathway is not clearly demonstrated as a mechanism of pathogenesis in complicated P.vivax malaria cases from Pakistan.     

An Optimal Au Grating Structure for Light Absorption in Amorphous Silicon Thin Film Solar Cell

Plasmonics - Effect of different gold (Au) grating structures on light absorption in solar cell is investigated by finite elemental analysis using COMSOL multiphysics-RF module. The geometry of the...     

Coupling Efficiency of Surface Plasmon Polaritons for 1D Plasmonic Gratings: Role of Under- and Over-Milling

This paper reports the successful excitation of surface plasmon polaritons (SPPs) through 1D metallic grating on higher refractive index GaP substrate. Coupling efficiency (η) of a free-space transverse-magnetic (TM) plane-wave mode into a SPP mode is crucial for many plasmonic devices. This η predominantly depends on the fabrication (milling) parameters and the factors (under- and over-milling) affecting the η is investigated experimentally and numerically. First of all, η is estimated by measuring the transmission spectra obtained through the plasmonic grating structures by varying the slit width (a) for a fixed period (Λ) and the thickness (t) of the gold (Au) film in which the grating is formed. The wave vector of the incident light is tuned to match the wave vector of the SPP, to get maximum η. For an optimum Au film thickness, a slit width of half of the periodicity of 770 nm in the grating device yields a maximum η. Such grating devices support only a fundamental plasmonic mode because the profile/shape of the slit in the grating device is more like a sinusoidal nature. Furthermore, such grating offers intermediate scattering to the incident light and the SPP as well which in-truns couple more incident energy to the SPPs. Moreover, over-milling results in decreased η where the crystalline plane of the substrate is disturbed. Finite element method (FEM) in COMSOL modeling is used to understand the underlying physics. This study is very useful for the development of the device application in real word.     

A central source of movement variability

Movements are universally, sometimes frustratingly, variable. When such variability causes error, we typically assume that something went wrong during the movement. The same assumption is made by recent and influential models of motor control. These posit that the principal limit on repeatable performance is neuromuscular noise that corrupts movement as it occurs. An alternative hypothesis is that movement variability arises before movements begin, during motor preparation. We examined this possibility directly by recording the preparatory activity of single cortical neurons during a highly practiced reach task. Small variations in preparatory neural activity were predictive of small variations in the upcoming reach. Effect magnitudes were such that at least half of the observed movement variability likely had its source during motor preparation. Thus, even for a highly practiced task, the ability to repeatedly plan the same movement limits our ability to repeatedly execute the same movement.     

Constitutive expression of CCR2 chemokine receptor and inhibition by MCP-1/CCL2 of GABA-induced currents in spinal cord neurones

In the CNS, immune-like competent cells (microglia and astrocytes) were first described as potential sites of chemokine synthesis, but more recent evidence has indicated that neurones might also express chemokines and their receptors. The aim of the present work was to investigate further, both in vivo and in vitro, CC Chemokine Family Receptor 2 (CCR2) expression and functionality in rat spinal cord neurones. First, we demonstrated by RT-PCR and western blot analysis that CCR2 mRNA and protein were present in spinal extracts. Furthermore, we showed by immunolabelling that CCR2 was exclusively expressed by neurones in spinal sections of healthy rat. Finally, to test the functionality of CCR2, we used primary cultures of rat spinal neurones. In this model, similar to what was observed in vivo, CCR2 mRNA and protein were expressed by neurones. Cultured neurones stimulated with Monocyte Chemoattractant Protein-1 (MCP-1)/CCL2, the best characterized CCR2 agonist, showed activation of the Akt pathway. Finally, patch-clamp recording of cultured spinal neurones was used to investigate whether MCP-1/CCL2 could modulate their electrophysiological properties. MCP-1 alone did not affect the electrical properties of spinal neurones, but potently and efficiently inhibited GABA(A)-mediated GABAergic responses in these neurones. These data constitute the first demonstration of a modulatory role of MCP-1 on GABAergic neurotransmission and contribute to our understanding of the roles of CCR2 and MCP-1/CCL2 in spinal cord physiology, in particular with respect to nociceptive transmission, as well as the implication of this chemokine in neuronal adaptation or dysfunction during neuropathy.     

Continuous degradation of maltose by enzyme entrapment technology using calcium alginate beads as a matrix

Maltase from Bacillus licheniformis KIBGE-IB4 was immobilized within calcium alginate beads using entrapment technique. Immobilized maltase showed maximum immobilization yield with 4% sodium alginate and 0.2 M calcium chloride within 90.0 min of curing time. Entrapment increases the enzyme–substrate reaction time and temperature from 5.0 to 10.0 min and 45 °C to 50 °C, respectively as compared to its free counterpart. However, pH optima remained same for maltose hydrolysis. Diffusional limitation of substrate (maltose) caused a declined in V_max of immobilized enzyme from 8411.0 to 4919.0 U ml^?1 min^?1 whereas, K_m apparently increased from 1.71 to 3.17 mM ml^?1. Immobilization also increased the stability of free maltase against a broad temperature range and enzyme retained 45% and 32% activity at 55 °C and 60 °C, respectively after 90.0 min. Immobilized enzyme also exhibited recycling efficiency more than six cycles and retained 17% of its initial activity even after 6th cycles. Immobilized enzyme showed relatively better storage stability at 4 °C and 30 °C after 60.0 days as compared to free enzyme.     

The chemokine BRAK/CXCL14 regulates synaptic transmission in the adult mouse dentate gyrus stem cell niche

The chemokine BRAK/CXCL14 is an ancient member of the chemokine family whose functions in the brain are completely unknown. We examined the distribution of CXCL14 in the nervous system during development and in the adult. Generally speaking, CXCL14 was not expressed in the nervous system prior to birth, but it was expressed in the developing whisker follicles (E14.5) and subsequently in the hair follicles and skin. Postnatally, CXCL14 was also highly expressed in many regions of the brain, including the cortex, basal ganglia, septum and hippocampus. CXCL14 was also highly expressed in the dorsal root ganglia. We observed that in the hippocampal dentate gyrus (DG) CXCL14 was expressed by GABAergic interneurons. We demonstrated that CXCL14 inhibited GABAergic transmission to nestin-EGFP-expressing neural stem/progenitor cells in the adult DG. CXCL14 inhibited both the tonic and phasic effects of synaptically released GABA. In contrast CXCL12 enhanced the effects of GABA at these same synapses. CXCL14 increased [Ca(2+)](i) in neural stem cells cultured from the postnatal brain indicating that they expressed the CXCL14 receptor. These observations are consistent with the view that CXCL12 and CXCL14 may normally act as positive and negative regulators of the effects of GABA in the adult DG stem cell niche.