A chitosan grafted mesoporous carbon aerogel for ultra-sensitive voltammetric determination of isoniazid

A screen-printed carbon electrode (SPCE) was modified with chitosan (Chit) supported on carbon aerogel (CA) to obtain an electrochemical sensor for the tuberculosis drug isoniazid (INZ). The interconnected mesoporous structure of Chit/CA provides a large surface area (S_BET = 461 m² g^-1) and good porosity (V_Tot = 0.69 cm³ g^-1). Besides, the modified SPCE displayed enhanced electrocatalytic activity due to the presence of numerous active sites (such as >C=O, -NH-, -NH₂, -OH). Figures of merit include (a) a typical working voltage of 0.28 V (vs. Ag/AgCl), (b) high sensitivity (8.09 μA μM^-1 cm^-2), (c) a wide linear response to INZ (0.01-115 μM) and (d) a low detection limit (8 nM). The modified electrode has successfully been applied to the determination of INZ in spiked serum and urine, and recoveries ranged from 97.8 to 99.8%. Graphical abstract Schematic illustration of preparation and applications of a nanocomposite consisting of chitosan (Chit; CS) supported on carbon aerogel (CA) for electrochemical detection of isoniazid.

Efficient nitrogen-vacancy centers' fluorescence excitation and collection from micrometer-sized diamond by a tapered optical fiber in endoscope-type configuration

Using an optical fiber to both excite the nitrogen-vacancy (NV) center in diamond and collect its fluorescence is essential to build NV-based endoscope-type sensor. Such endoscope-type sensor can reach inaccessible fields for traditional NV-based sensors built by bulky optical components and extend the application areas. Since single NV's fluorescence is weak and can easily be buried in fluorescence from optical fiber core's oxide defects excited by the green laser, fixing a micrometer size diamond containing high-density NVs rather than a nanodiamond containing single NV or several NVs on the apex of an optical fiber to build an endoscope-type sensor is more implementable. Unfortunately, due to small numerical aperture (NA), most of the optical fibers have a low fluorescence collection efficiency, which limits the sensitivity and spatial resolution of the NV-based endoscope-type sensor. Here, using a tapered optical fiber (TOF) tip, we significantly improve the efficiency of the laser excitation and fluorescence collection of the NV ensembles in diamond. This could potentially enhance the sensitivity and spatial resolution of the NV-based endoscope-type sensor. Numerical calculations show that the TOF tip delivers a high NA and has a high NV excitation and fluorescence collection efficiency. Experiments demonstrate that such TOF tip can obtain up to over 7-fold excitation efficiency and over 15-fold fluorescence collection efficiency of that from a flat-ended fiber (non-TOF) tip.

Effect of Bi-functional Hierarchical Flower-like CoS Nanostructure on its Interfacial Charge Transport Kinetics, Magnetic and Electrochemical Behaviors for Supercapacitor and DSSC Applications

Metal sulfides are of great interest for future electrode materials in supercapacitor and solar cell applications owing to their superior electrochemical activity and excellent electrical conductivity. With this scope, a binary transition metal sulfide (CoS) is prepared via one-step hydrothermal synthesis. Hexagonal phase of CoS with space group of P6₃/mmc(194) is confirmed by XRD analysis. Additional cubic Co₃S₄ phase in the prepared sample originates the mixed valence state of Co (Co²⁺ and Co³⁺) is affirmed from XPS analysis. Morphological features are visualized using HRSEM images that shows nanoflower shaped star-anise structure. Employing the prepared CoS as active electrode material, interfacial charge transport kinetics is examined by EIS-Nyquist plot. The supercapacitive performances are tested in two and three-electrode system which exhibited respective specific capacitances of 57 F/g and 348 F/g for 1 A/g. Further, the fabricated asymmetric CoS//AC supercapacitor device delivers an appreciable energy density of 15.58 Wh/kg and power density of 700.12 W/kg with excellent cyclic stability of 97.9% and Coulombic efficiency of 95% over 2000 charge-discharge cycles. In addition, dye-sensitized solar cells are fabricated with CoS counter electrode and the obtained power conversion efficiency of 5.7% is comparable with standard platinum based counter electrode (6.45%). Curie-Weiss plot confirms the transition of paramagnetic nature into ferrimagnetic behavior at 85 K and Pauli-paramagnetic nature at 20 K respectively. Temperature dependent resistivity plot affirms the metallic nature of CoS sample till 20 K and transition to semiconducting nature occurs at <20 K owing to Peierl’s transition effect.

Enhancement of superconducting properties and flux pinning mechanism on Cr0.0005NbSe2 single crystal under Hydrostatic pressure

Superconducting properties of Cr_0.0005NbSe₂ (T_c~6.64 K) single crystals have been investigated through the temperature dependent resistivity (~8 GPa) and DC magnetization (~1 GPa) measurements. Further, the critical current density (J_c) as a function of applied magnetic field has been studied from magnetic isotherms. The vortex pinning mechanisms have also been systematically analyzed using weak collective pinning theory as a function of pressure. The J_c corresponds to the flux flow enhanced by the application of pressure due to increase of T_c and vortex changes. We found that the pressure is responsible for the spatial variations in the charge carrier mean free path (δl pinning). We find that core point pinning is more dominant than surface pinning which is caused by the application of pressure. In addition, J_c(H = 0) increases from 3.9 × 10⁵ (0 GPa) to 1.3 × 10⁶ (1.02 GPa) A/cm² at 2 K as the pressure is increased from normal pressure to 1.02 GPa. The pressure dependence of T_c (dT_c/dP) becomes 0.91 K/GPa and 0.75 K/GPa from magnetization and resistivity measurements respectively. We found that the pressure promotes the anisotropy nature, and decrease of coherence length and resulting in pathetic interface of the vortex core with pinning centers.

The Evidence for External Beam Radiotherapy in High-Risk Neuroblastoma of Childhood: A Systematic Review

AIMS

External beam radiotherapy is widely used in various ways in the management of neuroblastoma. Despite extensive clinical experience, the precise role of radiotherapy in neuroblastoma remains unclear. The purpose of this systematic review was to survey the published literature to identify, without bias, the evidence for the clinical effectiveness of external beam radiotherapy as part of the initial multimodality treatment of high-risk neuroblastoma. We considered four areas: treatment of the tumour bed and residual primary tumour, identification of any dose-response relationship, treatment of metastatic sites, identification of any technical advances that may be beneficial. We also aimed to define uncertainties, which may be clarified in future clinical trials.

MATERIALS AND METHODS

Bibliographic databases were searched for neuroblastoma and radiotherapy. Reviewers assessed 1283 papers for inclusion by title and abstract, with consensus achieved through discussion. Data extraction on 57 included papers was carried out by one reviewer and checked by another. Studies were assessed for their level of evidence and risk of bias, and a descriptive analysis of data was carried out.

RESULTS

Fifteen papers provided some evidence that radiotherapy to the tumour bed and residual tumour may possibly be of value. However, there is a significant risk of bias and no evidence that all subgroups will benefit. There is some suggestion from six papers that dose may be important, but no hard evidence. It remains unclear whether irradiation of metastatic sites is helpful. Technical advances may be of value in radiotherapy of high-risk neuroblastoma.

CONCLUSIONS

There are data that show that radiotherapy is of some efficacy in the management of high-risk neuroblastoma, but there is no level one evidence that shows that it is being used in the best possible way. Prospective randomised trials are necessary to provide more evidence to guide development of optimal radiotherapy treatment schedules.

Pretreatment loss to follow-up of tuberculosis patients in Chennai, India: a cohort study with implications for health systems strengthening

Background

Pretreatment loss to follow-up (PTLFU) is a barrier to tuberculosis (TB) control in India’s Revised National TB Control Programme (RNTCP). PTLFU studies have not been conducted in India’s mega-cities, where patient mobility may complicate linkage to care.

Methods

We collected data from patient registries for May 2015 from 22 RNTCP designated microscopy centers (DMCs) in Chennai and audited addresses and phone numbers for patients evaluated for suspected TB to understand how missing contact information may contribute to PTLFU. From November 2015 to June 2016, we audited one month of records from each of these 22 DMCs and tracked newly diagnosed smear-positive patients using RNTCP records, phone calls, and home visits. We defined PTLFU cases as including: (1) patients who did not start TB therapy within 14 days and (2) patients who started TB therapy but were lost to follow-up or died before official RNTCP registration. We used multivariate logistic regression to identify factors associated with PTLFU.

Results

In the audit of May 2015 DMC registries, out of 3696 patients evaluated for TB, 1273 (34.4%) had addresses and phone numbers that were illegible or missing. Out of 344 smear-positive patients tracked from November 2015 to June 2016, 40 (11.6%) did not start TB therapy within 14 days and 36 (10.5%) started therapy but were lost to follow-up or died before official RNTCP registration, for an overall PTLFU rate of 22.1% (95%CI: 17.8%—26.4%). Of all PTLFU patients, 55 (72.4%) were lost to follow-up and 21 (27.6%) died before starting treatment or before RNTCP registration. In the regression analysis, age > 50 years (OR 2.9, 95%CI 1.4—6.5), history of prior TB (OR 3.9, 95%CI 2.2—7.1), evaluation at a high patient volume DMC (OR 3.2, 95% CI 1.7—6.3), and absence of legible patient contact information (OR 4.5, 95%CI 1.3—15.1) were significantly associated with PTLFU.

Conclusions

In an Indian mega-city, we found a high PTLFU rate, especially in patients with a prior TB history, who are at greater risk for having drug-resistance. Enhancing quality of care and health system transparency is critical for improving linkage of newly diagnosed patients to TB care in urban India.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3039-3) contains supplementary material, which is available to authorized users.

Development of METAL-ACTIVE SITE and ZINCCLUSTER tool to predict active site pockets

The advent of whole genome sequencing leads to increasing number of proteins with known amino acid sequences. Despite many efforts, the number of proteins with resolved three dimensional structures is still low. One of the challenging tasks the structural biologists face is the prediction of the interaction of metal ion with any protein for which the structure is unknown. Based on the information available in Protein Data Bank, a site (METALACTIVE INTERACTION) has been generated which displays information for significant high preferential and low-preferential combination of endogenous ligands for 49 metal ions. User can also gain information about the residues present in the first and second coordination sphere as it plays a major role in maintaining the structure and function of metalloproteins in biological system. In this paper, a novel computational tool (ZINCCLUSTER) is developed, which can predict the zinc metal binding sites of proteins even if only the primary sequence is known. The purpose of this tool is to predict the active site cluster of an uncharacterized protein based on its primary sequence or a 3D structure. The tool can predict amino acids interacting with a metal or vice versa. This tool is based on the occurrence of significant triplets and it is tested to have higher prediction accuracy when compared to that of other available techniques.

γ-MnS films with 3D microarchitectures: comprehensive study of the synthesis, microstructural, optical and magnetic properties

A simple procedure to synthesize 3D microarchitectures of γ-MnS films at low temperature is described in the present work.

Effect of pressure on normal and superconducting state properties of iron based superconductor PrFeAsO0.6F y (y = 0.12, 0.14)

The effect of high pressure (up to 8 GPa) on normal and superconducting state properties of PrFeAsO_0.6F_0.12, an 1111-type iron based superconductor close to optimal doped region, has been investigated by measuring the temperature dependence of resistivity. Initially, the superconducting transition temperature (T _c ) is observed to increase slowly by about 1 K as pressure (P) increases from 0 to 1.3 GPa. With further increase in pressure above 1.3 GPa, T _c decreases at the rate of ~1.5 K/GPa. The normal-state resistivity decreases monotonically up to 8 GPa. We have also measured the pressure dependence of magnetization (M) on the same piece of PrFeAsO_0.6F_0.12 sample up to 1.1 GPa and observed T _c as well as the size of the Meissner signal to increase with pressure in this low-pressure region. In contrast, for an over-doped PrFeAsO_0.6F_0.14 sample, magnetization measurements up to 1.06 GPa show that both T _c and the Meissner signal decrease with pressure. The present study clearly reveals two distinct regions in the dome-shaped (T _c -P) phase diagram of PrFeAsO_0.6F_0.12.

Enhancement of superconducting critical current density by Fe impurity substitution in NbSe2 single crystals and the vortex pinning mechanism

Magnetization measurements have been used to determine the effect of magnetic impurities (Fe) on the Larkin-Ovchinnikov (LO) 3D collective pinning model in NbSe₂ single crystals. Upon increasing the concentration of Fe impurities, the superconducting critical current density enhances appreciably compared to pure NbSe₂ reflecting the fact that the addition of magnetic impurities assists in improving the practical applicability of NbSe₂. The random pinning potential that is introduced by the Fe impurities also shows a considerable change in the interaction between the vortices and the core region, resulting in a competitive nature of single vortex, small bundle and large bundle pinning regimes in the H-T phase diagram. The intrinsic disorder in pure NbSe₂ single crystals shows δT_c flux pinning; however, the extrinsic disorder created by Fe atoms in NbSe₂ shows δl flux pinning. Furthermore, the field dependence of the pinning force on both NbSe₂ and Fe-incorporated NbSe₂ represents the existence of point pinning and the surface pinning mechanism with a broadening of the f_p curves in the Fe-incorporated single crystals.

Real time molecular detection of Chikungunya and dengue virus in the female Aedes mosquitoes collected in Chennai, Tamilnadu, India

Monsoon favors the breeding sites of many mosquito borne viral vectors resulting in increased outbreaks of vector borne infections, such as Chikungunya and dengue infections in the post monsoon period. Hence a pre-monsoon surveillance study of competent vectors carrying Chikungunya and dengue virus would help in better management of vectors and infections. Thus a surveillance study was carried out in Chennai before the onset of monsoon to study the distribution of competent vectors and detection of Chikungunya and dengue virus in female Aedes mosquitoes. Mosquitoes were collected from north, south, east and west zone of Chennai during March to July 2014. Chikungunya (CHIKV) and Dengue virus (DENV) were detected from the collected mosquitoes by Reverse Transcription Real time PCR (RT-PCR) followed by virus isolation in Vero cells. The most predominant species was Culex quinquefasciatis followed by Culex pipiens in the premonsoon period in our study. Viral infection rate during March to July (Premonsoon period) with respect to CHIKV and DENV virus were 0.456. The central zones of Chennai were highly found to inhabit the Aedes species in comparison to other zones surveyed during the premonsoon period. Viral infection rate of CHIKV and DENV were very low in female Aedes mosquitoes during the Pre-Monsoon period in Chennai.

Crystal Growth, Structure, Resistivity, Magnetic, and Photoelectric Properties of One-Dimensional Selenometallate Ba2 BiFeSe5

Low-dimensional materials have attracted extensive research interest in recent years owing to their interesting structural chemistry and physical properties, which will greatly deepen our knowledge of these materials and could lead to additional breakthroughs in the future. Herein we have synthesized and characterized Ba₂ BiFeSe₅ , which adopts a quasi-one-dimensional structure and possesses some fascinating physical properties. The sharp divergences between the field-cooled (FC) and the zero-field-cooled (ZFC) data and the rather small magnetic moment per Fe³⁺ (0.07 μ_B ) strongly suggest that the title compound is weakly ferromagnetic with a high magnetic transition temperature above room temperature, which is controlled by competing super-exchange interactions within and between [FeBiSe₅ ]_∞ anionic ladders. Moreover, with its narrow bandgap of 0.95 eV, Ba₂ BiFeSe₅ shows photoelectric properties with a photocurrent density of approximately 30 mA cm² at 5 V. Our study demonstrates that Ba₂ FeBiSe₅ might be a new type of multifunctional material that deserves further investigation.

Performance study of a laboratory model shallow solar pond with and without single transparent glass cover for solar thermal energy conversion applications

The thermal performance of a shallow solar pond with and without the single transparent glass cover has been investigated experimentally. This experiment has been performed during the summer season of 2014 under the operational condition for five different storage volumes of water upto a maximum of 10liter. The pond performance is investigated in terms of the rate of energy collected and its collection efficiency. A Low Density Polyethylene (LDPE) black sheet liner of 200μm thickness was laid on all the interior sides of the pond for solar energy absorption. A clear transparent PVC plastic sheet of 150μm thickness was laid over the water surface as evaporation suppressing membrane. Calibrated Copper constantan thermocouples were used to measure the temperatures of the system. A highest temperature of 81.5°C has been achieved for the stored volume of 2liter of water, when the pond was used with a single transparent glass cover of 5mm thickness. When the shallow solar pond was used without the transparent glass cover the system attained a maximum temperature of 62°C for the same stored volume of 2liter. A comparison between the two conditions of with and without the transparent glass cover, on the thermal performance of the SSP has been reported. A shallow solar pond system of the present type could be used us a source of warm water, of desired temperature, below 10°C which are required for the domestic and industrial utilities. The global warming is increased day by day; inorder to reduce global warming a typical method of small scale shallow solar pond has been used to absorb the radiation from the sun to convert it to useful heat energy by the source of water. The SSP is an eco friendly way to generate energy without polluting our environment and in an environment safety manner. Based on environmental safety this study has experimentally investigated the thermal performance of the shallow solar pond.

Evaluation of New Antibacterial Drugs and their Combinations in a Murine Model to Identify Short Duration Alternative Chemotherapy for Leprosy

The objective of the research is to test the efficacy of new drugs and drug combinations in mice infected with Mycobacterium leprae (M. leprae) as alternative to current WHO MDT. Individual drugs tested were Rifampicin (RMP), Rifapentine (RPT) and Moxifloxacin (MOXI). Drug combinations were RMP, Clarithromycin (CLARI), Minocycline (MINO) and RMP, MINO and Ofloxacin (OFLO). RPT drug combinations were RPT, CLARI, MINO and RPT, OFLO, MINO. Both the drugs and drug combinations were used as daily regimen and intermittent regimen. WHO MB MDT served as a positive control. Mice pre-inoculated with M. leprae were allotted to daily and intermittent groups and administered selected drugs and drug combinations. At the end of 12 months post sub-inoculation, mice were sacrificed and the proportion % of viable bacilli were counted using Spearman and Karber method. It was noted that RMP, RPT and Moxifloxacin indicated a range of 89.99% to 99.99% bactericidal effect when used in daily or intermittent doses in both normal and TR mice. Drug combinations showed bactericidal effect comparable to that of WHO MDT. From the study it was concluded that if the present duration of MDT has to be shortened then daily dose regimen with RMP/MINO/OFLO or RPT/CLARI/MINO are recommended for a clinical trial.

Evaluation of anti-bacterial activity of Rifapentine, Clarithromycin, Minocycline, Moxifloxacin, Ofloxacin and their combinations in Murine Model of Rifampicin Resistant Leprosy

Leprosy, a debilitating disease of the skin and peripheral nerves is caused by Mycobacterium leprae (M. leprae) and is treated by multidrug therapy (MDT) comprising of Dapsone, Rifampicin and Clofazimine. Resistance to any of these drugs poses a threat to the current disease control strategies. With the emergence of Rifampicin resistance in leprosy, it is important that alternative drugs need to be tested to develop a treatment strategy to combat drug resistant leprosy. In the current study, we have investigated WHO MDT, Rifapentine, Clarithromycin, Minocycline, Moxifloxacin, Ofloxacin and their combinations in intermittent and daily dose regimens in rifampicin resistant strains of M. leprae through mouse foot pad experiments in order to determine the loss in viability of M. leprae in response to these drugs and their combinations. Our findings suggest that WHO MDT is still the best combination in Rifampicin resistance cases. Combination of Moxifloxacin with Minocycline and Clarithromycin may also be taken up for clinical trials in cases with Rifampicin resistant leprosy. Rifapentine and Moxifloxacin can be effective alternative drugs to replace Rifampicin where required either in daily dose shorter duration regimens or intermittent dose longer regimen to treat resistant strains.

Effect of Fe on the Martensitic Transition, Magnetic and Magnetocaloric Properties in Ni-Mn-In Melt-spun Ribbons

The effect of Fe on the martensitic transitions, magnetic and inverse magnetocaloric effect in Ni47Mn40-xFexIn13 ribbons (x = 1, 2, 3 and 5) has been investigated. All the ribbon compositions under study have shown the presence of austenite phase at room temperature. The variation of martensitic transition with the increase in Fe-content is non-monotonic. The thermal hysteresis of the martensitic transition increased with the increase in Fe-content. The martensitic transitions shifted to lower temperatures in the presence of high magnetic fields. A maximum magnetic entropy change (∆SM) of 50 Jkg-1K-1 has been achieved in the Ni47Mn38Fe2In13 (x = 1) ribbon at 282 K for an applied field of 5 T.