Inhibited spontaneous emission of quantum dots weakly coupled to off resonant silver nanoplatelets and silver nanowires

Spontaneous emission (SE) rate of any light emitters directly scales with the locally available modes for photons. The emission rate can be modified, by changing the dielectric environment of light emitters. Generally cavities with modes in resonance to light emission frequency, are used to amplify the light emission rate. The Fermi golden rule predicts that if the cavity modes are offresonant to the emission frequency, then the SE rate is suppressed. In this study, we demonstrate that the SE of colloidal alloyed quantum dots is inhibited by coupling them to chemically synthesized Silver nanowires and Silver nanoplatelet systems. The silver nanoplatelet and silver nanowire plasmonic resonance modes are in ultraviolet and infrared regions of the electromagnetic spectrum. The quantum dots emit in visible region of light. This off-resonant weak coupling of emitters and cavities results in emission rate suppression and is quantified by time resolved photoluminescence (TRPL) measurements. TRPL decay profiles show that the emission rate can be suppressed by coupling self assembled quantum dot monolayers to a single silver nanoplatelet and a single silver nanowire respectively

Antimicrobial resistance pattern, clustering mechanisms and correlation matrix of drug-resistant Escherichia coli in black Bengal goats in West Bengal, India

A cross-sectional study covering four agro-climatic zones of West Bengal, India, was carried out to understand the risk-factors, antimicrobial resistance mechanism and clustering of the resistance characteristics of Escherichia coli isolated from healthy (170) and diarrhoeic (74) goats reared under intensive (52) and semi-intensive (192) farming practices. Of the 488 E. coli isolates, the majority, including the extended spectrum (n: 64, 13.11%) and AmpC β-lactamase (ACBL) (n: 86, 17.62%) producers, were resistant to tetracycline (25.2%), followed by enrofloxacin (24.5%), cefotaxime (21.5%) and amikacin (20.5%). Statistical modelling revealed that the isolates from diarrhoeic animals (p < 0.001) are likely to be more ACBL-positive than those from the healthy counterparts. Similarly, cefotaxime (p < 0.05) and enrofloxacin-resistance (p < 0.01) were significantly higher in diarrhoeic goats and in goats reared intensively. The isolates (n = 35) resistant to multiple drugs revealed the presence of β-lactamase [blaCTXM-1-(21), blaSHV-(7), blaTEM-(3), blaCMY-6-(1), blaCITM-(3)]; quinolone [qnrB-(10), qnrS-(7), aac(6’)-Ib-cr-(3)]; tetracycline [tetA-(19), tetB-(4)] and sulphonamide resistance determinants [sul1-(4)]; multiple plasmids, especially those belonging to the IncF and IncI1 replicon types; and active acrAB efflux pumps. Further, two isolates harbored the carbapenem resistance (blaNDM-5) gene and eight were strong biofilm producers. This first ever study conducted to unravel the status of AMR in goat farming reveals that not only the intensive farming practices but also certain clinical ailments such as diarrhoea can increase the shedding of the drug-resistant isolate. The emergence of multi-drug resistant (MDR) E. coli in goats, particularly those that are carbapenem resistant, is a cause for concern that indicates the spread of such pathogens even in the livestock sub-sector generally considered as naive

Tackling Child Undernutrition in India: Governance Challenges Need More Attention

This article puts a governance lens on India's current approach to tackling undernutrition through DFID's governance framework of state capability, accountability and responsiveness. State capability is analysed in terms of strength of political leadership to tackle undernutrition and to mobilise cross government actions. Accountability for results is assessed in the Integrated Child Development Scheme (ICDS) – India's foremost programme for children under six years of age with nutrition and health as one of the programme components. Finally, state responsiveness is assessed especially with respect to the Right?to?Food (RTF) campaign that has taken a legal route to advocacy by successfully petitioning the Supreme Court (SC) that has directed the Government of India (GoI) to improve the functioning of ICDS – with a special focus on the disadvantaged sections of the population

Microstructure control and wear of Al2O3-SiC-(Al,Si) composites made by melt oxidation

Ceramic matrix composites of Al2O3-SiC-(Al,Si) have been fabricated by directed melt oxidation of aluminum alloys into SiC particulate preforms. The proportions of Al2O3, alloy, and porosity in the composite can be controlled by proper selection of SLC particle size and the processing temperature. The wear resistance of composites was evaluated in pin-on-disk experiments against a hard steel substrate. Minimum wear rate comparable to conventional ceramics such as ZTA is recorded for the composition containing the highest fraction of alloy, owing to the development of a thin and adherent tribofilm with a low coefficient of friction

Sympathetic ophthalmitis following vitreoretinal surgery: Does antecedent trauma make a difference?

Background: Sympathetic ophthalmitis (SO) has been reported following vitrectomy; however, there is a lack of data on the role of antecedent penetrating ocular trauma impacting the disease manifestation in eyes developing SO following vitrectomy. Aim: To report differences in the presentation and outcomes of SO in eyes with or without a history of antecedent penetrating trauma; SO being diagnosed after vitreoretinal (VR) surgery. Design: Comparative case series. Methods: Seventeen consecutive patients presenting with SO following VR surgery, diagnosed between 1995 and 2011 were included. Eyes with and without prior penetrating injury were included in Group I (n = 7) and Group II (n = 10), respectively. All Group I patients had received systemic steroids prior to presentation. Demographic and clinical parameters were evaluated. Results: Differences were observed between Group I and Group II mainly with regards to time interval between VR surgery and diagnosis of SO (1.5 months vs. 8 months, P = 0.10), presence of neurosensory detachments (100% vs. 30%, P = 0.01), and the inciting eye vision at presentation (nil light perception in 28.5% vs. 80%, P = 0.049). Other differences observed though not statistically significant were optic disc and retinal vessel involvement (42% vs. 70%, P = 0.28), Dalen-Fuchs nodules (localized vs. diffuse) and leaks on fundus fluorescein angiography (pin-head vs. pin-point leak). Conclusion: SO in patients with antecedent penetrating ocular trauma present early with the central serous chorioretinopathy-like picture. Prior use of systemic steroids might have a bearing on the differences in presentation and the visual acuities between the two groups

Tuberculous uveitis presenting as pigmented hypopyon – A case report

Purpose: Hypopyon in the eye is an alarming sign. A case of tuberculous uveitis which presented with pigmented hypopyon has been described. The aim of this paper is to report pigmented hypopyon, a rare presentation of tuberculous uveitis in a diabetic patient. Observations: A 42-year-old patient with diabetes with a known history of miliary tuberculosis, on anti-tubercular therapy since two months presented with complaints of pain and redness followed by diminution of vision in the right eye since one month. Visual acuity was counting fingers close to face in right eye. Anterior chamber (AC) showed grade 4 cells and flare with a pigmented hypopyon measuring two mm. Fundus details were not made out. B scan revealed increased choroidal thickness with moderate vitritis. Routine blood counts revealed leucopenia and anemia suggestive of an immunosuppressed state. AC tap analysis was not helpful in diagnosis initially. Patient was lost to follow up and presented one month later with three - fourth of AC having hypopyon. AC wash was done and the AC sample evaluation revealed acid fast bacilli. Polymerase chain reaction results confirmed it to be Mycobacterium tuberculosis. Conclusions and importance: Tuberculous anterior uveitis thus presenting as pigmented hypopyon is very rare and can cause diagnostic difficulties. High index of suspicion in tuberculosis endemic areas is a must for a prompt diagnosis. A possible association between immunosuppression and pigmented hypopyon may exist and needs to be studied further

Cell-Membrane-Mimicking Lipid-Coated Nanoparticles Confer Raman Enhancement to Membrane Proteins and Reveal Membrane-Attached Amyloid-beta Conformation

Identifying the structures of membrane bound proteins is critical to understanding their function in healthy and diseased states. We introduce a surface enhanced Raman spectroscopy technique which can determine the conformation of membrane-bound proteins, at low micromolar concentrations, and also in the presence of a substantial membrane-free fraction. Unlike conventional surface enhanced Raman spectroscopy, our approach does not require immobilization of molecules, as it uses spontaneous binding of proteins to lipid bilayer-encapsulated Ag nanoparticles. We apply this technique to probe membrane-attached oligomers of Amyloid-beta(40) (A beta(40)), whose conformation is keenly sought in the context of Alzheimer's disease. Isotope-shifts in the Raman spectra help us obtain secondary structure information at the level of individual residues. Our results show the presence of a beta-turn, flanked by two beta-sheet regions. We use solid-state NMR data to confirm the presence of the beta-sheets in these regions. In the membrane-attached oligomer, we find a strongly contrasting and near-orthogonal orientation of the backbone H-bonds compared to what is found in the mature, less-toxic A beta fibrils. Significantly, this allows a ``porin'' like beta-barrel structure, providing a structural basis for proposed mechanisms of A beta oligomer toxicity

Involvement of ROS in Chlorogenic Acid-Induced Apoptosis of Bcr-Abl+ CML Cells

Chlorogenic acid (Chl) has been reported to possess a wide range of biological and pharmacological properties including induction of apoptosis of Bcr-Abl+ chronic myeloid leukemia (CML) cell lines and clinical leukemia samples via inhibition of Bcr-Abl phosphorylation. Here we studied the mechanisms of action of Chl in greater detail. Chl treatment induced an early accumulation of intracellular reactive oxygen species (ROS) in Bcr-Abl+ cells leading to downregulation of Bcr-Abl phosphorylation and apoptosis. Chl treatment upregulated death receptor DR5 and induced loss of mitochondrial membrane potential accompanied by release of cytochrome c from the mitochondria to the cytosol. Pharmacological inhibition of caspase-8 partially inhibited apoptosis, whereas caspase-9 and pan-caspase inhibitor almost completely blocked the killing. Knocking down DR5 using siRNA completely attenuated Chlinduced caspase-8 cleavage but partially inhibited apoptosis. Antioxidant NAC attenuated Chl-induced oxidative stress-mediated inhibition of Bcr-Abl phosphorylation, DR5 upregulation, caspase activation and CML cell death. Our data suggested the involvement of parallel death pathways that converged in mitochondria. The role of ROS in Chl-induced death was confirmed with primary leukemia cells fromCML patients in vitro as well as in vivo in nude mice bearing K562 xenografts. Collectively, our results establish the role of ROS for Chl-mediated preferential killing of Bcr-Abl+ cells