Surface functionalized perovskite nanocrystals: a design strategy for organelle-specific fluorescence lifetime multiplexing

Fluorescent molecules or materials with high photoluminescence quantum yields and stability towards photobleaching are ideally suited for multiplex imaging. Despite complying with such properties, perovskite nanocrystals (Pv-NCs) are rarely used for bioimaging owing to their toxicity and limited stability in aqueous media and towards human physiology. We aim to address these deficiencies by designing core–shell structures with Pv-NCs as the core and surface-engineered silica as the shell (SiO2@Pv-NCs) since silica is recognized as a biologically benign carrier material and is known to be excreted through urine. The post-grafting methodology is adopted for developing [SiO2@Pv-NCs]tpm and [SiO2@Pv-NCs]tsy (tpm: triphenylphosphonium ion, tsy: tosylsulfonamide) for specific imaging of mitochondria and endoplasmic reticulum (ER) of the live HeLa cell, respectively

Distinct repeat motifs at the C-terminal region of CagA of Helicobacter pylori strains isolated from diseased patients and asymptomatic individuals in West Bengal, India

Background: Infection with Helicobacter pylori strains that express CagA is associated with gastritis, peptic ulcer disease, and gastric adenocarcinoma. The biological function of CagA depends on tyrosine phosphorylation by a cellular kinase. The phosphate acceptor tyrosine moiety is present within the EPIYA motif at the C-terminal region of the protein. This region is highly polymorphic due to variations in the number of EPIYA motifs and the polymorphism found in spacer regions among EPIYA motifs. The aim of this study was to analyze the polymorphism at the C-terminal end of CagA and to evaluate its association with the clinical status of the host in West Bengal, India. Results: Seventy-seven H. pylori strains isolated from patients with various clinical statuses were used to characterize the C-ternimal polymorphic region of CagA. Our analysis showed that there is no correlation between the previously described CagA types and various disease outcomes in Indian context. Further analyses of different CagA structures revealed that the repeat units in the spacer sequences within the EPIYA motifs are actually more discrete than the previously proposed models of CagA variants. Conclusion: Our analyses suggest that EPIYA motifs as well as the spacer sequence units are present as distinct insertions and deletions, which possibly have arisen from extensive recombination events. Moreover, we have identified several new CagA types, which could not be typed by the existing systems and therefore, we have proposed a new typing system. We hypothesize that a cagA gene encoding higher number EPIYA motifs may perhaps have arisen from cagA genes that encode lesser EPIYA motifs by acquisition of DNA segments through recombination events

Evolution of strangeness in equilibrating and expanding quark-gluon plasma

We evaluate the strangeness production from equilibrating and transversely expanding quark gluon plasma which may be created in the wake of relativistic heavy ion collisions. We consider boost invariant longitudinal and cylindrically symmetric transverse expansion of a gluon dominated partonic plasma, which is in local thermal equilibrium. Initial conditions obtained from the self screened parton cascade model are used. We empirically find that the final extent of the partonic equilibration rises almost linearly with the square of the initial energy density. This along with the corresponding variation with the number of participants may help us distinguish between various models of parton production.Comment: RevTex, 10 pages including 6 figures comprising 11 postscript files, text modified considerably with an added figure (Fig. 6) and this version accepted for publication in Phys. Rev.

Post-Synthetic Modification of Covalent Organic Frameworks via in Situ Polymerization of Aniline for Enhanced Capacitive Energy Storage

Covalent organic frameworks (COFs) with layered architecture with open nanochannels and high specific surface areas are promising candidates for energy storage. However, the low electrical conductivity of two-dimensional COFs often limits their scope in energy storage applications. The conductivity of COFs can be enhanced through post-synthetic modification with conducting polymers. Herein, we developed polyaniline (PANI) modified triazine-based COFs via in situ polymerization of aniline with the porous frameworks. The composite materials showed high conductivity of 1.4-1.9 x 10-2 S cm-1 at room temperature with 10-fold enhancement in specific capacitance than the pristine frameworks. The fabricated supercapacitor exhibited a high energy density of 24.4 W h kg-1 and a power density of 200 W kg-1 at 0.5 A g-1 current density. Moreover, the device fabricated using the conducting polymer-triazine COF composite can light up a green light-emitting diode for 1 min after being charged for 10 s.</div

Single-Component White Light Emitting CdSexSy Alloy Nanocrystals Through Phosphine-Free Route

Semiconductor nanocrystals are promising for display and lighting devices. Herein, we report a facile one-pot synthetic route to fabricate white light emitting CdSexSy nanocrystals with enhanced quantum yield using CdO, S powder, and Se powder as precursors. The phosphine-free route was adopted, employing paraffin oil as the reducing agent and solvent for the fabrication. The optical properties can be effectively tailored by controlling the reaction time and the molar ratio of Se/S. The emission of pristine CdSexSy nanocrystals covered a broad visible range from 400 to 750 nm. The CdSexSy nanocrystals (Se/S = 0.4) exhibited white-light emission with quantum yield of 50 ± 3 % and Commission Internationale de l\u27Eclairage (CIE) chromaticity coordinates of (0.30, 0.31). The band-edge (~400-450 nm) to trap-state (~550-750 nm) emissions was tuned by controlling the Se/S ratio, and the different shades of white light were obtained. Furthermore, the quantum yield and CIE coordinates of the CdSexSy nanocrystals (Se/S = 0.4) were found to be similar even after 30 days of fabrication, showing the high stability of nanocrystals. The white light emission was retained in nanocrystals-embedded poly(methyl methacrylate) (PMMA) thin film and also in the hydrogel matrix. The one-pot, low-cost, scalable fabrication of white light emitting CdSexSy nanocrystals demonstrated in the present study offers promising scope in the solid-state display applications. <br /

Do the Learners are inclining towards the student credit card scheme? the reality and its prospect

Recently, taking an educational loan is a major concern of matter in the economics of education research. The researchers attempted to understand the perception of postgraduates’ students about the student credit card scheme launched by the state government of West Bengal in India. Three hundred fifty-four students were chosen randomly from 12 universities. Five points Likert-type scale was used to measure the perception of the students about student credit card. The researchers used a quasi-mixed method. Data were analysed by the use of descriptive, inferential statistics and also qualitatively by thematic analysis. The study found that the perception of the postgraduates ‘students about student credit card schemes has changed significantly due to their duration of study in university. But, perception about the same scheme has not been influenced by gender, age, academic stream, residential location, family income, caste category, availed or not of the scheme. Study also found that thirty six percent of students are satisfied with the scheme. On the other side large percent (47%) students are opposing the scheme in terms of either they feel not satisfied directly, or criticise this policy due to various reasons. However, some students favour it as the scheme has an inherent motive to promote students to receive higher education

Cerebral infarction following intracranial hemorrhage in pediatric Moyamoya disease – A case report and brief review of literature

Moyamoya disease is a clinical entity characterized by progressive cerebrovascular occlusion with spontaneous development of a collateral vascular network called Moyamoya vessels. This disease mainly manifests as cerebral ischemia. Intracranial bleeding is another major presentation of patients with Moyamoya disease. We report here a 12-year-old male child who presented with severe headache, vomiting and meningismus. Initial neuroimaging study with noncontrast computed tomography scan revealed fresh intraventricular hemorrhage in right-sided lateral ventricle. Magnetic resonance imaging with angiography of brain was done 5 days later when the child developed right-sided hemiparesis, and the diagnosis of Moyamoya disease was confirmed along with lacunar infarction of right posterior peri and paraventricular area and in the left paraventricular area and centrum semiovale. Simultaneous presence of cerebral infarction along with intraventricular hemorrhage in adult with bleeding-type Moyamoya disease is reported in literature, but it is a rare entity in a child

Performance of additive manufactured Stellite 6 tools in friction stir processing of CuCrZr sheet

In the recent time friction stir welding (FSW), a solid state welding process has rapidly gained attention for joining high melting point materials like Cu, Fe, Ti and their alloys apart from Al alloys due to its several advantages over fusion welding techniques. AISI H13, a versatile chromium–molybdenum hot work hardened steel, has been the most commonly used as a tool material for aluminium alloys. However, low tool life due to plastic deformation and wear at elevated temperatures is limiting its application in welding of high melting point materials. In the present work the performances of as-received, heat treated, laser remelted and Stellite 6 hardfaced H13 steel tools in friction stir processing (FSP) of CuCrZr have been investigated. Stellite 6 hardfaced FSW tools are developed by additive manufacturing (AM) process on H13 steel as a base material. In all these cases except the Stellite 6 hardfaced tool, the shoulder and pin are found to deform plastically with significant wear of shoulder along with the diffusion of CuCrZr into tool from tool pin-shoulder interface. However, tools developed by AM process are found to remain intact without any significant deformation or wear

Probing Conformational Stability and Dynamics of Erythroid and Nonerythroid Spectrin: Effects of Urea and Guanidine Hydrochloride

<div><p>We have studied the conformational stability of the two homologous membrane skeletal proteins, the erythroid and non-erythroid spectrins, in their dimeric and tetrameric forms respectively during unfolding in the presence of urea and guanidine hydrochloride (GuHCl). Fluorescence and circular dichroism (CD) spectroscopy have been used to study the changes of intrinsic tryptophan fluorescence, anisotropy, far UV-CD and extrinsic fluorescence of bound 1-anilinonapthalene-8-sulfonic acid (ANS). Chemical unfolding of both proteins were reversible and could be described as a two state transition. The folded erythroid spectrin and non-erythroid spectrin were directly converted to unfolded monomer without formation of any intermediate. Fluorescence quenching, anisotropy, ANS binding and dynamic light scattering data suggest that in presence of low concentrations of the denaturants (up-to 1M) hydrogen bonding network and van der Waals interaction play a role inducing changes in quaternary as well as tertiary structures without complete dissociation of the subunits. This is the first report of two large worm like, multi-domain proteins obeying twofold rule which is commonly found in small globular proteins. The free energy of stabilization (ΔG_u^H₂⁰) for the dimeric spectrin has been 20 kcal/mol lesser than the tetrameric from.</p></div