Simultaneous removal of organic and inorganic pollutants from water by Ni/NiO/SnO2 nanoparticles.

Herein, we report a facile synthesis of Ni/NiO/SnO2 hybrids where the core-shell-type Ni/NiO nanoparticle is decorated with the SnO2 nanoparticle to make a heterojunction and their potential evaluation for simultaneous removal of organic and inorganic pollutants. The metallic nickel core of the nanoparticle helps to separate easily from water magnetically and restricts the possible secondary contamination. The formation of semiconductor-semiconductor heterojunction enhances the photocatalytic activity to degrade the organic pollutants. The nanomaterial was characterized using microscopic, spectroscopic, and BET analyses. Results indicated an efficient degradation of ~ 94% of crystal violet in 40 min. An adsorption capacity of ~ 530 mg g-1 and ~ 650 mg g-1 of cadmium and lead ions, respectively, was found for single-component adsorption experiments, and ~ 520 mg g-1 and ~ 720 mg g-1 of cadmium and lead ions, respectively, were found for multi-component experiments. This observation suggested that the lead and cadmium ion adsorption process is affected by the synergistic and antagonistic effects, respectively. However, no significant change in the photocatalytic activity was observed for multi-component experiments. Results indicated that the process followed the Langmuir isotherm and pseudo-second-order kinetics irrespective of the number of pollutants present. An excellent adsorption capacity of metal ions and photodegradation capability of organic dye in multi-component solution, and possible reusability of the nanoparticle, make the Ni/NiO/SnO2 a potential material for simultaneous removal of organic and inorganic pollutants.

L-cysteine functionalized graphene quantum dots for sub-ppb detection of As (III).

Here, we report functionalized graphene quantum dots (GQDs) for the optical detection of arsenic at room temperature. GQDs with the fluorescence of three fundamental colors (red, green, and blue) were synthesized and functionally capped with L-cysteine (L-cys) to impart selectively towards As (III) by exploiting the affinity of L-cys towards arsenite. The optical characterization of GQDs was carried out using UV-vis absorption spectroscopy, Fourier transform infrared spectroscopy, and fluorescence spectrometry, and the structural characterizations were performed using transmission electron microscopy. The fluorescence results showed instantaneous quenching in intensity when the GQDs came in contact with As (III) for all test concentrations over a range from 0.025 to 25 ppb, which covers the permissible limit of arsenic in drinking water. The experimental results suggested excellent sensitivity and selectivity towards As (III).

Unique photoluminescence response of MoS2quantum dots over a wide range of As (III) in aqueous media.

We report the solvothermal synthesis of MoS2based quantum dots (QDs) and the performance evaluation of bare QDs for the detection of aqueous As (III) oxidative state at room temperature and neutral pH over a vast range (0.1-1000 ppb). Concentration-dependent photoluminescence (PL) of the QDs enhances up to 50 ppb and then suppresses till 1000 ppb. It shows two distinctive slopes for enhancement and suppression. The enhancement is possibly due to the passivation of trap states or defects. The formation of tiny glassy As2S3particles on the QD surface may be the possible reason for suppression. The pattern of optical absorption of QDs follows the similar patterns of PL. Still, it shows an enhanced absorbance in the near UV range below ≤300 nm, which increases with As (III) concentration up to 50 ppb and then decreases following the PL pattern. The MoS2QDs were characterized by using transmission electron microscopy, x-ray diffraction, UV-Vis, and PL spectroscopy. The enhancement and suppression results were excellently fitted with the modified Stern-Volmer equation. The detection of arsenic is possible using these linear fit equations as calibration curves.

Potassium Iodide-Functionalized Polyaniline Nanothin Film Chemiresistor for Ultrasensitive Ozone Gas Sensing.

Polyaniline (PANI) nanostructures have been widely studied for their sensitivity to atmospheric pollutants at ambient conditions. We recently showed an effective way to electropolymerize a PANI nanothin film on prefabricated microelectrodes, and demonstrated its remarkable sensing performance to be comparable to that of a one-dimensional nanostructure, such as PANI nanowires. In this work, we report further progress in the application of the PANI nanothin film chemiresistive sensor for the detection of ozone (O3) by modifying the film with potassium iodide (KI). The KI-PANI sensor exhibited an excellent sensitivity to O3 (8⁻180 ppb O3 concentration rage) with a limit of detection of 230 ppt O3, and exquisite selectivity against active chemicals such as nitrogen dioxide (NO2) and sulfur dioxide (SO2). The sensing mechanism of the sensor relied on iodometric chemistry of KI and O3, producing triiodide ( I 3 - ) that partially doped and increased electrical conductivity of the PANI film. The sensitivity and selectivity of the KI-functionalized PANI film demonstrates the potential use for KI-PANI-based O3 sensing devices in environmental monitoring and occupational safety.

Evaluation of facial artery perforator-based flaps in reconstruction of facial defects.

INTRODUCTION: Several flaps have been described for reconstructing facial or oral defects. Flaps such as forehead and pectoralis major are often too bulky for small-to-moderate-sized defects, for which nasolabial flaps are often ideal. However, nasolabial flaps have limited mobility and reach and may need two stages, particularly for intraoral defects. According to recent literatures, facial artery provides numerous small cutaneous perforators, based on which skin flaps can be islanded, with greater mobility and reach for reconstruction of small-to-moderate-sized intraoral and facial defects in one stage. Our study aims to evaluate the reliability and versatility of facial artery perforator-based flaps in the reconstruction of such defects. MATERIALS AND METHODS: A ethical committee-approved retrospective study was conducted on data of the patients attending our outpatient department between February 2014 and October 2015 with small-to-moderate-sized facial/oral lesions. The total sample size was 23. We studied the relation of flap survival with size of flap, route of inset and neck dissection, functional and aesthetic outcomes and feasibility of adjuvant therapy in cases of malignancies. RESULTS AND ANALYSIS: A wide range of facial defects, especially intraoral defects, could be reconstructed in one stage using facial artery perforator-based flaps. The flaps were reliable. Complications included only partial skin loss of the flaps in a few cases. Complications were directly related to the length of the flaps and the route of inset. Functional and aesthetic outcomes were satisfactory and none of the flaps showed any significant post-radiotherapy changes. CONCLUSIONS: We concluded that facial artery perforator flap can be a simple, safe, versatile and one-stage alternative to the traditional flaps in the reconstruction of small-to-moderate-sized facial defects. Neck dissection can be safely done in the same sitting.

A miniature chemiresistor sensor for carbon dioxide.

A carpet-like nanostructure of polyaniline (PANI) nanothin film functionalized with poly(ethyleneimine), PEI, was used as a miniature chemiresistor sensor for detection of CO2 at room temperature. Good sensing performance was observed upon exposing the PEI-PANI device to 50-5000 ppm CO2 in presence of humidity with negligible interference from ammonia, carbon monoxide, methane and nitrogen dioxide. The sensing mechanism relied on acid-base reaction, CO2 dissolution and amine-catalyzed hydration that yielded carbamates and carbonic acid for a subsequent pH detection. The sensing device showed reliable results in detecting an unknown concentration of CO2 in air.

Carbon nanotubes-based label-free affinity sensors for environmental monitoring.

Nanostructures, such as nanowires, nanobelts, nanosprings, and nanotubes, are receiving growing interest as transducer elements of bio/chemical sensors as they provide high sensitivity, multiplexing, small size, and portability. Single-walled carbon nanotubes (SWNTs) are one such class of nanostructure materials that exhibit superior sensing behavior due to its large-surface carbon atoms that are highly responsive to surface adsorption events. Further, their compatibility with modern microfabrication technologies and facile functionalization with molecular recognition elements make them promising candidates for bio/chemical sensors applications. Here, we review recent results on nanosensors based on SWNTs modified with biological receptors such as aptamers, antibodies, and binding proteins, to develop highly sensitive, selective, rapid, and cost-effective label-free chemiresistor/field-effect transistor nanobiosensors for applications in environmental monitoring.

Blast injuries to the hand: Pathomechanics, patterns and treatment.

PURPOSE: To characterize the common patterns of injury in detail in cases of blast injuries to the hand and to outline the possible pathomechanics of these patterns of injury while describing the treatment modalities for the same as practiced in our center. MATERIALS AND METHODS: A review of admitted patients in our department from september 2009 through december 2010 of blast injuries to the hand was made. Each patient had a careful characterization of their injuries as mild, moderate or severe with the help of X-rays, clinical photographs and operative notes. The treatment of these patients during hospital stay was also documented. RESULTS: Of the 55 patients studied, 5 patients suffered mild injuries with no bony injuries or dislocations, 26 patients had moderate injuries characterized by fractures and dislocations in addition to soft tissue injuries and 24 patients had severe injuries characterized by variable degrees of amputations. The most common injury type was to the radial aspect of the hand characterized by a first web split and a dislocation of the CMC joint of the thumb associated with fracture of the central metacarpals and amputations of the index and long fingers in some cases. Injury to the ulnar aspect was rare. Injuries were treated by repair as well as replacement done mostly in a serial fashion. CONCLUSION: Depending on the mode of injury, blast injuries to the hand can have varying patterns of injury, which can have important implications in the treatment and rehabilitation of a patient.

Label-free chemiresistive biosensor for mercury (II) based on single-walled carbon nanotubes and structure-switching DNA.

Herein, we present a sensitive, selective, and facile label-free DNA functionalized single-walled carbon nanotube (SWNT)-based chemiresistive biosensor for the detection of Hg(2+). SWNTs were functionalized with Hg(2+) binding 15-bases long polyT oligonucleotide through covalent attachment using a bilinker molecule. The polyT was further hybridized with polyA to form a polyT-polyA duplex. When exposed to Hg(2+) the polyT-polyA duplex was dehybridized combined with switching of polyT structure, leading to change in resistance/conductance of the SWNT chemiresistor device. The device provided a significant response within 100 to 1000 nM of Hg(2+) concentration with a 6.72 × 10(-3) nM(-1) sensitivity.

Porphyrins-Functionalized Single-Walled Carbon Nanotubes Chemiresistive Sensor Arrays for VOCs.

Single-walled carbon nanotubes (SWNTs) have been used extensively for sensor fabrication due to its high surface to volume ratio, nanosized structure and interesting electronic property. Lack of selectivity is a major limitation for SWNTs-based sensors. However, surface modification of SWNTs with a suitable molecular recognition system can enhance the sensitivity. On the other hand, porphyrins have been widely investigated as functional materials for chemical sensor fabrication due to their several unique and interesting physico-chemical properties. Structural differences between free-base and metal substituted porphyrins make them suitable for improving selectivity of sensors. However, their poor conductivity is an impediment in fabrication of prophyrin-based chemiresistor sensors. The present attempt is to resolve these issues by combining freebase- and metallo-porphyrins with SWNTs to fabricate SWNTs-porphyrin hybrid chemiresistor sensor arrays for monitoring volatile organic carbons (VOCs) in air. Differences in sensing performance were noticed for porphyrin with different functional group and with different central metal atom. The mechanistic study for acetone sensing was done using field-effect transistor (FET) measurements and revealed that the sensing mechanism of ruthenium octaethyl porphyrin hybrid device was governed by electrostatic gating effect, whereas iron tetraphenyl porphyrin hybrid device was governed by electrostatic gating and Schottky barrier modulation in combination. Further, the recorded electronic responses for all hybrid sensors were analyzed using a pattern-recognition analysis tool. The pattern-recognition analysis confirmed a definite pattern in response for different hybrid material and could efficiently differentiate analytes from one another. This discriminating capability of the hybrid nanosensor devices open up the possibilities for further development of highly dense nanosensor array with suitable porphyrin for E-nose application.

Thermal hysteresis of some important physical properties of nanoparticles.

Gold nanoparticles show thermal hysteresis with properties such as surface plasmon absorption, conductivity, and zeta potential. The direction of the incremental change in plasmon peak position and its extinction depend on the nature of surface conjugation. The thermal profile of a surface plasmon resonance spectrum for nanoparticles may serve as a signature for the associated small molecule or macromolecule on which it is seeded. The thermal responses of zeta potential and conductivity profile are found to be independent of the surface conjugation with the later being subjected to a phase transition phenomenon as revealed by a temperature criticality.

Gold nanoparticle-based tool to study protein conformational variants: implications in hemoglobinopathy.

The size of gold nanoparticles is shown here to gradually decrease if it is allowed to grow on a protein template, and the protein is subjected to unfolding by a nonionic denaturant. The correlation between size of the gold nanoparticle formed and the plasmon frequency observed remains linear, except at stages where protein folding intermediates are formed. Higher population of exposed tyrosine residues, number of sulfhydryl groups of the protein, and the overall exposition of the inner hydrophobic core may lead to the generation of smaller particles. The method provides a simple colorimetric sensing of protein conformation and has been tested for both nonheme and heme proteins (hemoglobin and bovine serum albumin). Similarly, protein variants with defects in folding (caused by subunit misassembly or mutation) can also be classified. Possible application of this approach in hemoglobinopathy (e.g., thalassemia carrier detection) is discussed in the text.