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18,976 result(s) for "Ansari, S."
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Influence of nanotechnology on herbal drugs: A Review
Herbal medicines have been widely used all over the world since ancient times and have been recognized by physicians and patients for their better therapeutic value as they have fewer adverse effects as compared with modern medicines. Phytotherapeutics need a scientific approach to deliver the components in a sustained manner to increase patient compliance and avoid repeated administration. This can be achieved by designing novel drug delivery systems (NDDS) for herbal constituents. NDDSs not only reduce the repeated administration to overcome non-compliance, but also help to increase the therapeutic value by reducing toxicity and increasing the bioavailability. One such novel approach is nanotechnology. Nano-sized drug delivery systems of herbal drugs have a potential future for enhancing the activity and overcoming problems associated with plant medicines. Hence, integration of the nanocarriers as a NDDS in the traditional medicine system is essential to conflict more chronic diseases like asthma, diabetes, cancer, and others.
IgE and IgG Antibodies as Regulators of Mast Cell and Basophil Functions in Food Allergy
Food allergy is a major health issue, affecting the lives of 8% of U.S. children and their families. There is an urgent need to identify the environmental and endogenous signals that induce and sustain allergic responses to ingested allergens. Acute reactions to foods are triggered by the activation of mast cells and basophils, both of which release inflammatory mediators that lead to a range of clinical manifestations, including gastrointestinal, cutaneous, and respiratory reactions as well as systemic anaphylaxis. Both of these innate effector cell types express the high affinity IgE receptor, FcϵRI, on their surface and are armed for adaptive antigen recognition by very-tightly bound IgE antibodies which, when cross-linked by polyvalent allergen, trigger degranulation. These cells also express inhibitory receptors, including the IgG Fc receptor, FcγRIIb, that suppress their IgE-mediated activation. Recent studies have shown that natural resolution of food allergies is associated with increasing food-specific IgG levels. Furthermore, oral immunotherapy, the sequential administration of incrementally increasing doses of food allergen, is accompanied by the strong induction of allergen-specific IgG antibodies in both human subjects and murine models. These can deliver inhibitory signals via FcγRIIb that block IgE-induced immediate food reactions. In addition to their role in mediating immediate hypersensitivity reactions, mast cells and basophils serve separate but critical functions as adjuvants for type 2 immunity in food allergy. Mast cells and basophils, activated by IgE, are key sources of IL-4 that tilts the immune balance away from tolerance and towards type 2 immunity by promoting the induction of Th2 cells along with the innate effectors of type 2 immunity, ILC2s, while suppressing the development of regulatory T cells and driving their subversion to a pathogenic pro-Th2 phenotype. This adjuvant effect of mast cells and basophils is suppressed when inhibitory signals are delivered by IgG antibodies signaling via FcγRIIb. This review summarizes current understanding of the immunoregulatory effects of mast cells and basophils and how these functions are modulated by IgE and IgG antibodies. Understanding these pathways could provide important insights into innovative strategies for preventing and/or reversing food allergy in patients.
Synthesis of Hollow Pt-Ni Nanoboxes for Highly Efficient Methanol Oxidation
In direct methanol fuel cell technology, highly stable electrochemical catalysts are critically important for their practical utilization at the commercial scale. In this study, sub ~10 nm hollow Pt-Ni (1:1 at. ratio) nanoboxes supported on functionalized Vulcan carbon (Pt-Ni/C-R2) were synthesized through a facile method for the efficient electrooxidation of methanol. Two reaction procedures, namely, a simultaneous reduction and a modified sequential reduction method using a reverse microemulsion (RME) method, were adopted to synthesize solid Pt-Ni NPs and hollow nanoboxes, respectively. To correlate the alloy composition and surface structure with the enhanced catalytic activity, the results were compared with the nanocatalyst synthesized using a conventional NaBH 4 reduction method. The calculated electroactive surface area for the Pt-Ni/C-R2 nanoboxes was 190.8 m 2 .g −1 , which is significantly higher compared to that of the Pt-Ni nanocatalyst (96.4 m 2 .g −1 ) synthesized by a conventional reduction method. Hollow nanoboxes showed 34% and 44% increases in mass activity and rate of methanol oxidation reaction, respectively, compared to solid NPs. These results support the nanoreactor confinement effect of the hollow nanoboxes. The experimental results were supported by Density Functional Theory (DFT) studies, which revealed that the lowest CO poisoning of the Pt 1 Ni 1 catalyst among all Pt m -Ni n mixing ratios may account for the enhanced methanol oxidation. The synthesized hollow Pt-Ni/C (R2) nanoboxes may prove to be a valuable and highly efficient catalysts for the electrochemical oxidation of methanol due to their low cost, numerous catalytically active sites, low carbon monoxide poisoning, large electroactive surface area and long-term stability.
A Generalization of Reciprocal Exponential Model: Clayton Copula, Statistical Properties and Modeling Skewed and Symmetric Real Data Sets
We introduce a new extension of the reciprocal Exponential distribution for modeling the extreme values. We used the Morgenstern family and the clayton copula for deriving many bivariate and multivariate extensions of the new model. Some of its properties are derived. We assessed the performance of the maximum likelihood estimators (MLEs) via a graphical simulation study. The assessment was based on the sample size. The new reciprocal model is employed for modeling the skewed and the symmetric real data sets. The new reciprocal model is better than some other important competitive models in statistical modeling.
IgG:FcγRIIb Signaling on Mast Cells Blocks Allergic Airway Inflammation
IgG antibodies, signaling via the inhibitory receptor, FcγRIIb, are potent inhibitors of IgE-mediated mast cell activation. We have previously reported that in addition to blocking mast cell degranulation, inhibitory IgG signals shut down a proinflammatory transcriptional program in which mast cells produce cytokines and chemokines known to drive type 2 tissue inflammation. To determine whether such effects of allergen-specific IgG can modulate allergic inflammation in vivo, we examined the airways of mice sensitized to ovalbumin (OVA) by intraperitoneal injection and then challenged with intranasal OVA. Pretreatment with allergen-specific IgG significantly reduced the recruitment of inflammatory cells, including macrophages and eosinophils, into the lungs of OVA-sensitized mice. The bronchoalveolar lavage fluid of OVA-challenged mice contained elevated levels of chemokine ligands (CCL2 and CCL24) and interleukin-5, a response that was markedly blunted in animals receiving allergen-specific IgG. IgG-treated animals exhibited attenuated allergen-induced production of IgE, IL-4, and IL-13, along with impaired OVA-induced goblet cell hyperplasia and Muc5ac expression and suppressed airway hyperresponsiveness, consistent with a shift away from a Th2 response. Using mice with a lineage-specific deletion of FcγRIIb, we demonstrated that each of these protective effects of IgG was dependent upon the expression of this receptor on mast cells. Overall, our findings establish that allergen-specific IgG can reduce allergen-driven airway inflammation and airway hyperresponsiveness and point to a mechanistic basis for the therapeutic benefit of aeroallergen-specific IgG therapy.
Electronic Structure, Optical and Transport Properties of Double Perovskite La2NbMnO6: A Theoretical Understanding from DFT Calculations
Double perovskite La2NbMnO6 was systematically studied using the first-principles calculations. The structural, electronic, optical and transport properties of this compound were calculated. Spin resolved band structure predicted this material as a half-metal with an energy gap of 3.75 eV in spin down state. The optical coefficients including optical conductivity, reflectivity and electron energy loss are calculated for photon energy up to 30.00 eV to understand the optical response of this perovskite. The strong absorption of all the ultraviolet and infrared frequencies of the spectrum by this material may suggest the potential application of this material for the optoelectronic devices in ultraviolet and infra-red region. Also, the thermoelectric properties with a speculation from the half-metallic electronic structure are reported. Subsequently, the Seebeck coefficient, electrical and thermal conductivity coefficients are calculated to predict the thermoelectric figure of merit (zT), the maximum of which is found out to be 0.14 at 800 K.
The maxima in northerly wind speeds and wave heights over the Arabian Sea, the Arabian/Persian Gulf and the Red Sea derived from 40 years of ERA5 data
Recent studies point out the importance of northerly winds and waves in the Arabian Sea, especially those due to shamal and makran events in addition to the northeast monsoon system. We have analyzed climatology and trends of northerly maximum wind speed and significant wave height (Hs) in the Arabian Sea and the connected marginal seas, Arabian/Persian Gulf and the Red Sea, during non-monsoon season derived from 40 years of ERA5 wind and wave data, and estimated monthly, annual and decadal extreme climate and their trends. The study brings out an increasing trend in the northerly maximum wind speed (0.8–1.2 cm/s/year) and Hs (0.42–0.88 cm/year) in the southern and central Arabian Sea, which is consistent with the global trend in extreme wind speed and Hs. The northern Arabian Sea including the Sea of Oman exhibits significant decreasing trend in northerly maximum wind speed (− 1.4 cm/s/year) and Hs (− 0.67 cm/year), while the Gulf and the Red Sea exhibit sectorial contrasting trend, indicating the dominance of localized effects in modifying the regional climate. Distinct features identified in the climate and trends of northerly winds and waves are further discussed.
Immune dysregulation caused by homozygous mutations in CBLB
CBL-B is an E3 ubiquitin ligase that ubiquitinates proteins downstream of immune receptors to downregulate positive signaling cascades. Distinct homozygous mutations in CBLB were identified in 3 unrelated children with early-onset autoimmunity, one of whom also had chronic urticaria. Patient T cells exhibited hyperproliferation in response to anti- CD3 cross-linking. One of the mutations, p.R496X, abolished CBL-B expression, and a second mutation, p.C464W, resulted in preserved CBL-B expression. The third mutation, p.H285L in the SH2 domain of CBL-B, was expressed at half the normal level in the patient's cells. Mice homozygous for the CBL-B p.H257L mutation, which corresponds to the patient's p.H285L mutation, had T and B cell hyperproliferation in response to antigen receptor cross-linking. [Cblb.sup.H257L] mice had increased percentages of T regulatory cells (Tregs) that had normal in vitro suppressive function. However, T effector cells from the patient with the p.H285L mutation and [Cblb.sup.H257L] mice were resistant to suppression by WT Tregs. Bone marrow- derived mast cells from [Cblb.sup.H257L] mice were hyperactivated after Fc[epsilon]RI cross-linking, and [Cblb.sup.H257L] mice demonstrated exaggerated IgE-mediated passive anaphylaxis. This study establishes CBL-B deficiency as a cause of immune dysregulation.
Uniform blue emitting carbon nanodots synthesized from fig fruit using reverse diffusion purification
In this investigation, blue-emitting carbon nanodots (B.CNDs) with exceptional color purity were successfully synthesized from fresh fig fruit using a one-step pyrolysis method. These B.CNDs are small and spherical (3.7 nm) with an amorphous carbon core encapsulated inside a passivated layer primarily composed of oxygen-related functional groups. They demonstrated an emission property that is independent of excitation, showing the highest emission intensity in the deep blue region at 450 nm with a narrow full-width at half maximum (FWHM) at 44 nm and a quantum yield of 15.5%. This exceptional value of FWHM is attributed to the remarkable uniformity in both morphological and chemical composition that was achieved through the utilization of the reverse diffusion technique combined with the dialysis method for purification and separation of B.CNDs. This work not only contributes to the expanding field of carbon nanomaterials but also introduces a novel and sustainable approach to fabricate CDs with unparalleled color purity and optical performance.
Nanostructured Cuprous-Oxide-Based Screen-Printed Electrode for Electrochemical Sensing of Picric Acid
The sensitive and selective electrochemical detection of picric acid (PA), a toxic, harmful environmental pollutant and an explosive, using different morphologies of cuprous oxide (Cu2O) is reported. The different Cu2O morphologies, synthesized by a hydrothermal method for 8 h, 10 h, and 12 h, were characterized using various techniques to confirm their morphological, optical, compositional, and structural properties. Sensors, fabricated in the form of screen-printed electrodes using these different morphologies of Cu2O, were used to study the electrochemical sensing capabilities of the nanomaterials for PA (7.8 μ M to 10.0 mM). Cyclic voltammetry studies revealed a distinct change in the redox peak current as a function of PA concentration, which was further confirmed by electrochemical impedance spectroscopy studies, as the charge-transfer resistance increased with an increase in PA concentration. Scan rate studies showed that the electrochemical sensing of PA is a surface-controlled process, involving rapid electron transfer. Among the different morphologies, Cu2O synthesized for 8 h showed a reproducible and reliable sensitivity of 130.4 μA mM−1 cm−2 with a limit of detection of 39 μM and good linearity over a wide range of PA concentrations. Interference studies with other phenolic compounds revealed the presence of distinct peaks corresponding to PA, indicating that the fabricated sensor shows specificity and selectivity for PA.