Rice is the main staple food in most of the Asian countries and rice crops generate a huge amount of rice straw as crop residue in the fields. Unsustainable use of rice straw and open burning of crop ...in the field not only produces threat to environment by producing large amount of greenhouse gas (GHG) emission, but also make farmer׳s loose a very viable by-product. Rice straw can be used in bio-ethanol production and bring additional income and sustainable utilization. It will also provide clean energy solution to ever increasing energy demand in India. However, it becomes more important to study the sustainability of bio-ethanol production from rice straw and how it can make sense in today׳s Indian agricultural scenario. Although, the bioethanol obtained from rice straw is a carbon neutral in nature, but the concerns of environmental impacts have been raised for the whole process i.e. from rice cultivation, rice logistics, pretreatment techniques, bioethanol generation and transportation. The present review focuses on the environmental sustainability issues arising from use of rice straw for bioethanol production. The environmental impacts are assessed by studying the emission of greenhouse gases from each stage of life cycle. The paper presents an outlook on current status and future prospects of ethanol blending in the country.
Label-free and sensitive detection of PSA (Prostate Specific Antigen) is still a big challenge in the arena of prostate cancer diagnosis in males. We present a comparative study for label-free PSA ...aptasensor and PSA immunosensor for the PSA-specific monoclonal antibody, based on graphene quantum dots-gold nanorods (GQDs-AuNRs) modified screen-printed electrodes. GQDs-AuNRs composite has been synthesized and used as an electro-active material, which shows fast electron transfer and catalytic property. Aptamer or anti-PSA has immobilized onto the surface of modified screen printed electrodes. Three techniques are used simultaneously, viz. cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedence spectroscopy (EIS) to investigate the analytical performance of both PSA aptasensor and PSA immunosensor with its corresponding PSA antigen. Under optimum conditions, both sensors show comparable results with an almost same limit of detection (LOD) of 0.14 ng mL
. The results developed with aptasensor and anti-PSA is also checked through the detection of PSA in real samples with acceptable results. Our study suggests some advantages of aptasensor in terms of better stability, simplicity and cost effectiveness. Further our present work shows enormous potential of our developed sensors for real application using voltammetric and EIS techniques simultaneous to get reliable detection of the disease.
Abstract
A series of Eu
3+
ions doped Ca
0.05
Y
1.93-
xO
3
:0.02Ho
3+
(CYO:Ho
3+
,xEu
3+
) nanophosphors having multicolour tuneability have been synthesised by following a simplistic solution ...combustion approach. The synthesised samples have been characterised by employing X-ray diffraction (XRD), Transmission electron microscope (TEM), and Fourier transforms infrared spectroscopy (FTIR). The optical properties have been engrossed by UV–visible and photoluminescent excitation and emission spectra, and decay lifetimes measurements. The characteristic emission, which occurs due to the f-f transition of Ho
3+
and Eu
3+
has been observed in emission spectra with excitation of 448 nm. By adjusting the doping ratio of Ho
3+
/Eu
3+
, the as-synthesized nanophosphor accomplishes multicolour tunability from green-yellow to red. Emission spectra and decay lifetime curve recommend dipole–dipole interaction causes energy transfer from Ho
3+
→ Eu
3+
. The energy transfer process from Ho
3+
to Eu
3+
has been confirmed through electric dipole–dipole interaction with critical distance 15.146 Å. Moreover, temperature dependent emission spectra show the high thermal stability with an activation energy ⁓ 0.21 eV, with the quantum efficiency of 83.6%. CIE coordinate illustrates that the singly doped Ho
3+
and Eu
3+
lie in the green and red region, respectively, while the as-synthesized CYO:Ho
3+
,xEu
3+
shows tunability from green to red with low CCT and high colour purity values. Hence, the CYO:Ho
3+
,xEu
3+
nanophosphor may be a near-UV excited multicolour colour-tunable pertinent candidate with potential prospects for multicolour- display and near-ultraviolet lighting applications.
Herein, we demonstrate the fabrication of highly capacitive activated carbon (AC) using a bio-waste Kusha grass (
Desmostachya bipinnata
), by employing a chemical process followed by activation ...through KOH. The as-synthesized few-layered activated carbon has been confirmed through X-ray powder diffraction, transmission electron microscopy, and Raman spectroscopy techniques. The chemical environment of the as-prepared sample has been accessed through FTIR and UV–visible spectroscopy. The surface area and porosity of the as-synthesized material have been accessed through the Brunauer–Emmett–Teller method. All the electrochemical measurements have been performed through cyclic voltammetry and galvanometric charging/discharging (GCD) method, but primarily, we focus on GCD due to the accuracy of the technique. Moreover, the as-synthesized AC material shows a maximum specific capacitance as 218 F g
−1
in the potential window ranging from − 0.35 to + 0.45 V. Also, the AC exhibits an excellent energy density of ~ 19.3 Wh kg
−1
and power density of ~ 277.92 W kg
−1
, respectively, in the same operating potential window. It has also shown very good capacitance retention capability even after 5000th cycles. The fabricated supercapacitor shows a good energy density and power density, respectively, and good retention in capacitance at remarkably higher charging/discharging rates with excellent cycling stability. Henceforth, bio-waste Kusha grass-derived activated carbon (DP-AC) shows good promise and can be applied in supercapacitor applications due to its outstanding electrochemical properties. Herein, we envision that our results illustrate a simple and innovative approach to synthesize a bio-waste Kusha grass-derived activated carbon (DP-AC) as an emerging supercapacitor electrode material and widen its practical application in electrochemical energy storage fields.
•1. Importance and necessity: Many different approaches have been developed for detection of H2O2 till date including different electrochemical methods, spectrophotometry, chromatography as well as ...fluorescence. Recently fluorescent semiconductor or quantum dots (QDS) have attracted much attention due to their broad absorption with narrow emission with high brightness and good stability. However, the synthesis of QDS is little difficult with multiple step and need some specific equipment. Nowadays, rare earth ions doped luminescent materials are highlighted as fluorescent materials with high yield, which have been used in various field including solar cell, phosphor, color display etc.•2. Originality and novelty: In the present work, we have prepared a highly dispersed Eu:Y2O3 fluorescent flexible film of poly vinyl alcohol (EYCP film) for non-enzymatic detection of H2O2 by turn off probe for fluorescence using a solution combustion method.•3. Contribution and impact: The fluorescence spectra of EYCP has a number of emission sharp peak ranging from 560 nm to 700 nm corresponding to electrical dipole and magnetic dipole transition from excited 5D0→7Fj (j = 0, 1, 2, 3, 4) energy levels of doped Eu+3 ion in Y2O3 host. These excitation energy bands are attributed to charge transfer from the 2p orbital of oxygen to the 4f orbital of europium. The intense intensity peaks occurs at ∼611 nm corresponding to 5D0→7F2 transition. The EYCP film shows excellent fluorescence quenching in presence of H2O2 by significantly increasing concentration of H2O2 and completely quenched at ∼150 μM. This work gives insight for synthesis of rare earth metal doped oxide flexible film with great fluorescence properties and makes a room for further development of high quality of film for bio sensing with efficient performance. A linear relationship is observed between 0.0 and 60 μM with a correlation coefficient of 0.0989. This study is expected to have a significant impact on further study of the Eu:Y2O3 fluorescent flexible film for wide range application.•We also believe that our work represents a methodological and scientific approach We are excited to share our manuscript with you and look forward to your positive response.
In this work, a novel sensing scaffold consisting highly dispersed Eu:Y2O3 fluorescent flexible film of poly vinyl alcohol (EYCP) was synthesized by simple mixing method and applied to facilitate non-enzymatic detection of hydrogen peroxide (H2O2) by turn off probe of fluorescence. The fluorescence spectra of EYCP consisting number of emission sharp transitions from excited, 5D0→7Fj (j=0, 1, 2, 3, 4) energy levels of doped Eu3+ ion in Y2O3 host. In the presence of H2O2, the fluorescence intensity of the EYCP film was quenched due to the reduction of electron–hole pair recombination in Eu centers by electron transfer from Eu–O excited state to H2O2 energy level rather than 5D0 state of Eu3+, which reduces the number of electron in 5D0 state. The EYCP film shows excellent fluorescence quenching in presence of H2O2 by significantly increasing concentration of H2O2 and completely quenched at ∼150μM. A linear relationship is observed between 0.0 and 60μM with a correlation coefficient of 0.989. H2O2 sensing is also compared with the EYC nanoparticles. This study is expected to have a significant impact on further study of the Eu:Y2O3 fluorescent flexible film for wide range applications.
During T cell-dependent responses, B cells can either differentiate extrafollicularly into short-lived plasma cells or enter follicles to form germinal centers (GCs). Interactions with T follicular ...helper (Tfh) cells are required for GC formation and for selection of somatically mutated GC B cells. Interleukin (IL)-21 has been reported to play a role in Tfh cell formation and in B cell growth, survival, and isotype switching. To date, it is unclear whether the effect of IL-21 on GC formation is predominantly a consequence of this cytokine acting directly on the Tfh cells or if IL-21 directly influences GC B cells. We show that IL-21 acts in a B cell-intrinsic fashion to control GC B cell formation. Mixed bone marrow chimeras identified a significant B cell-autonomous effect of IL-21 receptor (R) signaling throughout all stages of the GC response. IL-21 deficiency profoundly impaired affinity maturation and reduced the proportion of IgG1(+) GC B cells but did not affect formation of early memory B cells. IL-21R was required on GC B cells for maximal expression of Bcl-6. In contrast to the requirement for IL-21 in the follicular response to sheep red blood cells, a purely extrafollicular antibody response to Salmonella dominated by IgG2a was intact in the absence of IL-21.
Herein, we report the electrochemical detection of roxarsone (ROX) on a two-dimensional (2D) activated carbon (AC)-modified glassy carbon electrode (GCE). Meso/microporous 2D-AC is synthesized from a ...natural biomass Desmostachya bipinnata, commonly known as Kusha in India. This environment-friendly material is synthesized by chemical activation using potassium hydroxide (KOH) and used as a sensitive electrochemical platform for the determination of ROX. It is an arsenic-based medicine, also used as a coccidiostat drug. It is widely used in poultry production as a feed additive to increase weight gain and improve feed efficiency. Long-term exposure to arsenic leads to serious health problems in humans and demands an urgent call for sensitive detection of ROX. Therefore, the green synthesis of 2D-AC is introduced as new carbon support for the electrochemical sensing of ROX. It provides a large surface area and efficiently supports enhanced electron transfer. Its electrocatalytic activity is seen in potassium ferri/ferrocyanide by cyclic voltammetry, where the 2D-AC-modified GCE delivered five to six times higher electrochemical performance as compared to the unmodified GCE. Electrochemical impedance spectroscopy is also performed to show that the prepared material has faster electron transfer and permits a diffusion-controlled process. It works well in real samples and also on disposable screen-printed carbon electrodes, thereby showing great potential for its application in clinical diagnosis. Our results exemplify a modest and innovative style for the synthesis of excellent electrode material in the electrochemical sensing platform and thus offer an inexpensive and highly sensitive novel approach for the electrochemical sensing of ROX and other similar drugs.
Fatty acid molecules 9,12,15-octadecatrienoic acid (C18:3), 9,12-octadecadienoic acid (C18:2), and hexadecanoic acid (C16:0) possessing active functional groups with the capability of fast electron ...transfer have been established for effective corrosion inhibition of mild steel. In this regard, a microalga Scenedesmus sp. is isolated and its fatty acids have been studied to corroborate the adsorption behavior, attributing the anticorrosion efficacy on mild steel in 1 M HCl solution by forming metal–inhibitor framework. Electrochemical analysis has been used to ascertain the surpassing corrosion inhibition efficiency at an optimal concentration of 36 ppm with maximum 95.1% inhibitive performance. The results of metallography with or without the inhibitor molecules have indicated significant changes in surface morphology of mild steel specimen for gradual enhancement in immersion time (72 h). Hydrogen evolution reaction has been emphasized to observe the tendency of significant decrease in the bubble formation in the presence of inhibitor compared to 1 M HCl solution only. Surface morphometric studies (scanning electron microscopy and atomic force microscopy) have also revealed the excellent adsorption capacity of Scenedesmus fatty acids on metal surface. Quantum chemical calculations, performed by density functional theory, determined significant adsorption effectiveness, based on the donor–acceptor capability between metallic surface and inhibitor molecules.
Interaction configurations and Current–Voltage characteristics of (a) Cu-B-Graphene-H2O-As, (b) Cu-N-Graphene - H2O-As complexes and (c) Response of pristine and functionalized sheets.
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•Presence of Arsenic in drinking water detected using pristine and Cu decorated graphene sheets.•The interaction of Cu and N atom with As analyzed through electronic and transport properties.•Cu functionalization of N-graphene improvises the response of the sheet by 189%.•The response of pristine graphene is observed to be 19% at the low biasing voltage.•Cu-N-Graphene detected arsenic with improved response at low operating voltage of ~200mV.
The pristine graphene (G) and copper decorated boron/nitrogen doped graphene (Cu-B/NG) nanosheets have been computationally analyzed and demonstrated for their detection ability towards Arsenic, presence in the aqueous environment. The sheet’s detection ability has been analyzed in terms of it’s interaction stability and the observed variations in electronic and transport properties. The results reveal that the interaction stability of As has improved significantly for the Cu-BG/NG sheets in comparison to the pristine graphene. The computed electronic properties deduce the adsorption of As, transforms the semiconducting behavior of the Cu-BG/NG sheets into metallic, leading to the variation in its conductance. The observed variation in conductance found to be 25% and 55% for Cu-BG and Cu-NG sheets, respectively, which are relatively higher than the one computed for its pristine (19%) counterpart. Thus, the above results confirm that the functionalization of graphene sheet via doping and decoration with nitrogen and copper, respectively (Cu-NG), enhances the sheet's response by 189%, compared to the pristine sheet. Therefore, Cu-NG nanosheet can be implemented as a potential candidate as Arsenic detector in the aqueous environment.
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•Rectangular ZnO Nanowire modeled for gas sensing application.•Adsorption of CO2 explored in terms of electronic and transport properties of ZnO nanowire.•The sensitivity of ...rectangular ZnO nanowire towards CO2 ∼ 5 times higher than earlier reports.
We report the toxic gas sensing ability of ZnO Nanowire performed by using Density Functional Theory (DFT) based first principle approach. The ZnO Nanowire with rectangular morphology has been modeled and investigated for its energetic stability, analysed in terms of binding energy. The adsorption of a single molecule of carbon dioxide (CO2) gas on the fully relaxed rectangular ZnO Nanowire has been analysed through its dynamic response discussed in terms of conductance. The sensing ability has been evaluated further through adsorption energy, electronic band structure, density of states, Mullikan population and current-voltage analysis of the Nanowire. It has been observed that CO2 is physisorbed on the rectangular ZnO Nanowire via van-der-Waals interaction and relatively shows higher sensitivity of this morphology over other reports, defends this as a good candidate for CO2 sensing using ZnO structures.
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