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1.
Nanotechnology ; 35(29)2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38604130

RESUMO

Numerous efforts have been undertaken to mitigate the Debye screening effect of FET biosensors for achieving higher sensitivity. There are few reports that show sub-femtomolar detection of biomolecules by FET mechanisms but they either suffer from significant background noise or lack robust control. In this aspect, deformed/crumpled graphene has been recently deployed by other researchers for various biomolecule detection like DNA, COVID-19 spike proteins and immunity markers like IL-6 at sub-femtomolar levels. However, the chemical vapor deposition (CVD) approach for graphene fabrication suffers from various surface contamination while the transfer process induces structural defects. In this paper, an alternative fabrication methodology has been proposed where glass substrate has been initially texturized by wet chemical etching through the sacrificial layer of synthesized silver nanoparticles, obtained by annealing of thin silver films leading to solid state dewetting. Graphene has been subsequently deposited by thermal reduction technique from graphene oxide solution. The resulting deformed graphene structure exhibits higher sensor response towards glial fibrillary acidic protein (GFAP) detection with respect to flat graphene owing to the combined effect of reduced Debye screening and higher surface area for receptor immobilization. Additionally, another interesting aspect of the reported work lies in the biomolecule capture by dielectrophoretic (DEP) transport on the crests of the convex surfaces of graphene in a coplanar gated topology structure which has resulted in 10 aM and 28 aM detection limits of GFAP in buffer and undiluted plasma respectively, within 15 min of application of analyte. The detection limit in buffer is almost four decades lower than that documented for GFAP using biosensors which is is expected to pave way for advancing graphene FET based sensors towards ultrasensitive point-of-care diagnosis of GFAP, a biomarker for traumatic brain injury.


Assuntos
Técnicas Biossensoriais , Proteína Glial Fibrilar Ácida , Grafite , Humanos , Técnicas Biossensoriais/métodos , Eletroforese/métodos , Vidro/química , Proteína Glial Fibrilar Ácida/análise , Grafite/química , Limite de Detecção , Nanopartículas Metálicas/química , Prata/química , Transistores Eletrônicos
2.
Cryo Letters ; 45(2): 122-133, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38557991

RESUMO

BACKGROUND: Acorus calamus Linn. is a medicinally valuable monocot plant belonging to the family Acoraceae. Over-exploitation and unscientific approach towards harvesting to fulfill an ever-increasing demand have placed it in the endangered list of species. OBJECTIVE: To develop vitrification-based cryopreservation protocols for A. calamus shoot tips, using conventional vitrification and V cryo-plate. MATERIALS AND METHODS: Shoot tips (2 mm in size) were cryopreserved with the above techniques by optimizing various parameters such as preculture duration, sucrose concentration in the preculture medium, and PVS2 dehydration time. Regenerated plantlets obtained post-cryopreservation were evaluated by random amplified polymorphic DNA (RAPD) to test their genetic fidelity. RESULTS: The highest regrowth of 88.3% after PVS2 exposure of 60 min was achieved with V cryo-plate as compared to 75% after 90 min of PVS2 exposure using conventional vitrification. After cryopreservation, shoot tips developed into complete plantlets in 28 days on regrowth medium (0.5 mg/L BAP, 0.3 mg/L GA3, and 0.3 mg/L ascorbic acid). RAPD analysis revealed 100% monomorphism in all cryo-storage derived regenerants and in vitro donor (120-days-old) plants. CONCLUSION: Shoot tips of A. calamus that were cryopreserved had 88.3% regrowth using V cryo-plate technique and the regerants retained genetic fidelity. https://doi.org/10.54680/fr24210110412.


Assuntos
Acorus , Plantas Medicinais , Criopreservação/métodos , Plantas Medicinais/genética , Técnica de Amplificação ao Acaso de DNA Polimórfico , Brotos de Planta/genética , Vitrificação , Crioprotetores
3.
Cryo Letters ; 44(4): 219-228, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37883139

RESUMO

BACKGROUND: Podophyllum hexandrum is a highly endangered valuable medicinal plant of the Himalayas belonging to family Berberidaceae. This plant needs conservation efforts due to the over-exploitation and unscrupulous harvesting from the wild because of its ever-increasing demand. OBJECTIVE: To establish a long-term cryopreservation method for Podophyllum hexandrum using two techniques: Vitrification and V Cryo-plate. MATERIALS AND METHODS: Zygotic embryos were cryopreserved using vitrification and V cryo-plate by optimization of parameters including preculture time, loading time and PVS2 dehydration time. Recovery of zygotic embryos was performed on different regrowth media for plantlet formation. RESULTS: With V cryo-plate, 90% regrowth was obtained as compared to 73.3% with vitrification. V Cryo-plate conditions were pre-culture of zygotic embryos in 0.3 M sucrose for 4 days, treatment in loading solution with 0.8 M sucrose for 20 min, dehydration in PVS2 for 50 min, LN exposure, unloading in 1.2 M sucrose for 20 min and transfer of zygotic embryos to regrowth medium for recovery. During recovery, the maximum number of shoots (4.2) and highest shoot length (5.1 cm) were observed on regrowth medium with 1.5 mg per liter BAP and 0.1 mg per liter IAA (R7). CONCLUSION: Zygotic embryos of Podophyllum hexandrum were cryopreserved with 90% regrowth using a V cryoplate technique and plantlets were produced directly after cryopreservation. Doi: 10.54680/fr23410110712.


Assuntos
Plantas Medicinais , Vitrificação , Criopreservação/métodos , Desidratação , Crioprotetores/farmacologia , Brotos de Planta , Sacarose
4.
Med J Armed Forces India ; 79(2): 141-151, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36969131

RESUMO

Background: Cancer incidence is rising across the globe. The incidence and patterns of various cancers among Armed Forces Personnel and Veterans is not known. We did the analysis of registry data maintained at our hospital. Methods: A retrospective analysis was performed of all patients registered at our hospital cancer registry between 01st January 2017 and 31st December 2019. Patients were registered with unique identification number. Baseline demographics and cancer subtype data were retrieved. Patients with histopathologically proven diagnosis and age ≥18 years were studied. Armed Forces Personnel (AFP) were defined as those who are in active service, and Veterans as those who had retired from service at the time of registration. Patients with Acute and Chronic Leukemias were excluded. Results: New cases registered were 2023, 2856 and 3057 in year 2017, 2018, 2019 respectively. AFP, Veterans and dependents among them were 9.6%, 17.8%, and 72.6% respectively. Haryana, Uttar Pradesh and Rajasthan represented 55% of all cases with male to female ratio 1.14:1 and median age was 59 years. The median age among AFP was 39 years. Among AFP as well as veterans, Head and Neck cancer was the most common malignancy. Cancer incidence was significantly higher in adults >40 years as compared to <40 years. Conclusion: Seven percent rise per year of new cases in this cohort is alarming. Tobacco-related cancers were the most common. There is an unmet need to establish a prospective centralized Cancer Registry to better understand the risk factors, outcomes of treatment and strengthen the policy matters.

5.
J Appl Microbiol ; 131(3): 1147-1161, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33544959

RESUMO

AIMS: In the age where bacterial resistance to conventional antibiotics is increasing at an alarming rate, the use of the traditional plant, herb extracts or other bioactive constituents is gradually becoming popular as an anti-virulence agent to treat pathogenic diseases. Carvacrol, a major essential oil fraction of Oregano, possesses a wide range of bioactivities. Therefore, we aimed to study the effect of sub-inhibitory concentrations of carvacrol on major virulence traits of Vibrio cholerae. METHODS AND RESULTS: We have used in vitro as well as ex vivo models to access the anti-pathogenic role of carvacrol. We found that the sub-inhibitory concentration of carvacrol significantly repressed bacterial mucin penetrating ability. Carvacrol also reduced the adherence and fluid accumulation in the rabbit ileal loop model. Reduction in virulence is associated with the downregulated expression of tcpA, ctxB, hlyA and toxT. Furthermore, carvacrol inhibits flagellar synthesis by downregulating the expression of flrC and most of the class III genes. CONCLUSIONS: Carvacrol exhibited anti-virulence activity against V. cholerae, which involved many events including the inhibition of mucin penetration, adhesion, reduced expression of virulence-associated genes culminating in reduced fluid accumulation. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings indicate that carvacrol possesses inhibitory activity against V. cholerae pathogenesis and might be considered as a potential bio-active therapeutic alternative to combat cholera.


Assuntos
Cólera , Óleos Voláteis , Origanum , Vibrio cholerae , Animais , Proteínas de Bactérias , Cólera/tratamento farmacológico , Cimenos , Óleos Voláteis/farmacologia , Coelhos , Vibrio cholerae/genética , Virulência
6.
J Environ Manage ; 295: 113035, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34167061

RESUMO

Several industrial wastes including biomass, fly ashes, red mud, mill scales, water treatment residues, have significant concentrations of metal oxides: Fe2O3, Al2O3, TiO2, SiO2 etc. Several efforts have been made towards recovering metals within these wastes. Rather than recovering one metal at a time, we report a novel approach for simultaneously extracting multiple metals from mixed oxides in a single process step. Using three distinct furnaces/heating regimes, the carbothermic reduction of Fe2O3/Al2O3/SiO2 system was investigated at 1450-1700 °C for up to 2 h over a wide composition range. Complete reduction was achieved for both Fe2O3 and SiO2 in all cases leading to the formation of Fe and Fe-Si alloys. The reduction of alumina at moderate temperatures was the key challenge. No alumina reduction was observed during reductions at 1450 °C. A partial reduction of alumina and the formation of Fe-Al alloys was detected in the Al2O3/Fe2O3/C system at 1550 °C. The formation of Fe-Si-Al alloys was also observed in the Fe2O3/SiO2/Al2O3/C system at 1550 °C. Complete reduction of alumina was observed at 1600-1700 °C, even for up to 50 wt% alumina in the system. Optimal operating conditions and reference standards were established for the simultaneous recovery of multiple metals from waste oxides. While conserving natural resources, this novel route will lower the burden on waste storage facilities with significant contributions to the economic and environmental sustainability of industrial waste management.


Assuntos
Resíduos Industriais , Ferro , Óxido de Alumínio , Cinza de Carvão , Resíduos Industriais/análise , Dióxido de Silício
7.
Cryo Letters ; 42(5): 300-308, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-35363851

RESUMO

BACKGROUND: Valeriana jatamansi Jones is a medicinal plant of the Himalayan region with high trade value. Since overexploitation of this wild species led it to be listed as threatened, a comprehensive conservation strategy is needed. Cryopreservation would be a useful complementary method to conventional conservation methods. OBJECTIVE: To develop a cryopreservation protocol for V. jatamansi with maintenance of biosynthetic stability of regenerants. MATERIALS AND METHODS: In vitro shoot tips were cryopreserved using vitrification with either PVS2 or PVS3 and the efficacy of the two cryoprotectant mixtures compared. Regenerated plantlets were evaluated by HPLC analysis for contents of four valepotriates viz. valtrate, acevaltrate, didrovaltrate and IVHD valtrate. RESULTS: The highest shoot recovery (91.6%) after transfer to liquid nitrogen was obtained when shoot tips were treated with PVS2 at 0°C for 110 min, which was significantly higher than the highest recovery (73.3%) obtained using PVS3 for any duration tested. Evaluation of biosynthetic stability showed no variation in valepotriate contents between in vitro maintained and cryopreserved derived plantlets. CONCLUSION: This protocol will be useful for the long-term conservation of this species as high frequency recovery and biosynthetic stability after cryopreservation were obtained.


Assuntos
Plantas Medicinais , Valeriana , Criopreservação/métodos , Brotos de Planta , Vitrificação
8.
Philos Trans A Math Phys Eng Sci ; 377(2149): 20190007, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31130099

RESUMO

Magnetic materials with strong local interactions but lacking long-range order have long been a curiosity of physicists. Probing their magnetic interactions is crucial for understanding the unique properties they can exhibit. Metal-organic frameworks have recently gathered more attention as they can produce more exotic structures, allowing for controlled design of magnetic properties not found in conventional metal-oxide materials. Historically, magnetic diffuse scattering in such materials has been overlooked but has attracted greater attention recently, with advances in techniques. In this study, we investigate the magnetic structure of metal-organic formate frameworks, using heat capacity, magnetic susceptibility and neutron diffraction. In Tb(DCO2)3, we observe emergent magnetic order at temperatures below 1.2 K, consisting of two k-vectors. Ho(DCO2)3 shows diffuse scattering above 1.6 K, consistent with ferromagnetic chains packed in a frustrated antiferromagnetic triangular lattice, also observed in Tb(DCO2)3 above 1.2 K. The other lanthanides show no short- or long-range order down to 1.6 K. The results suggest an Ising-like one-dimensional magnetic order associated with frustration is responsible for the magnetocaloric properties, of some members in this family, improving at higher temperatures. This article is part of the theme issue 'Mineralomimesis: natural and synthetic frameworks in science and technology'.

9.
Artigo em Inglês | MEDLINE | ID: mdl-29866870

RESUMO

Central-line-associated bloodstream infections are increasingly recognized to be associated with intraluminal microbial biofilms, and effective measures for the prevention and treatment of bloodstream infections remain lacking. This report evaluates a new commercially developed antimicrobial catheter lock solution (ACL), containing trimethoprim (5 mg/ml), ethanol (25%), and calcium EDTA (Ca-EDTA) (3%), for activity against bacterial and fungal biofilms, using in vitro and in vivo (rabbit) catheter biofilm models. Biofilms were formed by bacterial (seven different species, including vancomycin-resistant Enterococcus [VRE]) or fungal (Candida albicans) species on catheter materials. Biofilm formation was evaluated by quantitative culture (CFU) and scanning electron microscopy (SEM). Treatment with ACL inhibited the growth of adhesion-phase biofilms in vitro after 60 min (VRE) or 15 min (all others), while mature biofilms were completely inhibited after exposure for 2 or 4 h, compared to control. Similar results were observed for drug-resistant bacteria. Compared to the heparinized saline controls, ACL lock therapy significantly reduced the catheter bacterial (3.49 ± 0.75 versus 0.03 ± 0.06 log CFU/catheter; P = 0.016) and fungal (2.48 ± 1.60 versus 0.55 ± 1.19 log CFU/catheter segment; P = 0.013) burdens in the catheterized rabbit model. SEM also demonstrated eradication of bacterial and fungal biofilms in vivo on catheters exposed to ACL, while vigorous biofilms were observed on untreated control catheters. Our results demonstrated that ACL was efficacious against both adhesion-phase and mature biofilms formed by bacteria and fungi in vitro and in vivo.


Assuntos
Antifúngicos/farmacologia , Bactérias/efeitos dos fármacos , Biofilmes/efeitos dos fármacos , Antibacterianos/farmacologia , Candida albicans/efeitos dos fármacos , Enterococcus/efeitos dos fármacos , Microscopia Eletrônica de Varredura
10.
J Assoc Physicians India ; 66(8): 40-44, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31324083

RESUMO

OBJECTIVE: To determine the diagnostic accuracy of Stress Myocardial Perfusion Imaging (MPI) in diagnosing Stable Ischemic Heart Disease (SIHD). METHODS: To analyze the sensitivity and specificity of Stress Myocardial Perfusion Imaging (MPI) in diagnosing Stable Ischemic Heart Disease (SIHD) by comparing with "gold standard" Coronary Angiogram. RESULTS: A total of 80 patients were studied (51 male, 29 female). 52 patients had significant stenosis in coronary angiography and 49 patients had reversible perfusion defect in myocardial perfusion imaging (MPI). MPI had a sensitivity of 88.46% and a specificity of 89.29% in diagnosing stable ischemic heart disease. CONCLUSION: Coronary Angiography remains the near gold standard in diagnosing ischemic heart disease but is associated with serious complications like stroke, arrhythmias, acute renal failure, infection, etc. Though Myocardial perfusion imaging cannot replace coronary angiogram, it can be used as a reliable and sensitive non-invasive alternate investigation to diagnose stable ischemic heart disease in high risk individuals who are unwilling for angiogram.


Assuntos
Doença da Artéria Coronariana/diagnóstico por imagem , Isquemia Miocárdica/diagnóstico por imagem , Imagem de Perfusão do Miocárdio , Angiografia Coronária , Feminino , Humanos , Masculino , Sensibilidade e Especificidade , Tomografia Computadorizada de Emissão de Fóton Único
11.
J Antimicrob Chemother ; 71 Suppl 1: i3-19, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-27048580

RESUMO

OBJECTIVES: To provide susceptibility data for community-acquired respiratory tract isolates of Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae and Moraxella catarrhalis collected in 2012-14 from four Asian countries. METHODS: MICs were determined using Etest(®) for all antibiotics except erythromycin, which was evaluated by disc diffusion. Susceptibility was assessed using CLSI, EUCAST and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints. For macrolide/clindamycin interpretation, breakpoints were adjusted for incubation in CO2 where available. RESULTS: Susceptibility of S. pneumoniae was generally lower in South Korea than in other countries. Penicillin susceptibility assessed using CLSI oral or EUCAST breakpoints ranged from 21.2% in South Korea to 63.8% in Singapore. In contrast, susceptibility using CLSI intravenous breakpoints was much higher, at 79% in South Korea and ∼95% or higher elsewhere. Macrolide susceptibility was ∼20% in South Korea and ∼50%-60% elsewhere. Among S. pyogenes isolates (India only), erythromycin susceptibility (∼20%) was lowest of the antibiotics tested. In H. influenzae antibiotic susceptibility was high except for ampicillin, where susceptibility ranged from 16.7% in South Korea to 91.1% in India. South Korea also had a high percentage (18.1%) of ß-lactamase-negative ampicillin-resistant isolates. Amoxicillin/clavulanic acid susceptibility for each pathogen (PK/PD high dose) was between 93% and 100% in all countries except for H. influenzae in South Korea (62.5%). CONCLUSIONS: Use of EUCAST versus CLSI breakpoints had profound differences for cefaclor, cefuroxime and ofloxacin, with EUCAST showing lower susceptibility. There was considerable variability in susceptibility among countries in the same region. Thus, continued surveillance is necessary to track future changes in antibiotic resistance.


Assuntos
Antibacterianos/farmacologia , Infecções Comunitárias Adquiridas/microbiologia , Farmacorresistência Bacteriana , Haemophilus influenzae/efeitos dos fármacos , Moraxella catarrhalis/efeitos dos fármacos , Infecções Respiratórias/microbiologia , Streptococcus/efeitos dos fármacos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Sudeste Asiático/epidemiologia , Criança , Pré-Escolar , Infecções Comunitárias Adquiridas/epidemiologia , Monitoramento Epidemiológico , Haemophilus influenzae/isolamento & purificação , Humanos , Índia/epidemiologia , Lactente , Recém-Nascido , Masculino , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Moraxella catarrhalis/isolamento & purificação , Infecções Respiratórias/epidemiologia , Streptococcus/classificação , Streptococcus/isolamento & purificação , Adulto Jovem
12.
Scand J Immunol ; 83(2): 92-101, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26478541

RESUMO

An avirulent, live transconjugant Shigella hybrid (LTSHΔstx) strain was constructed in our earlier study by introducing a plasmid vector, pPR1347, into a Shiga toxin gene deleted Shigella dysenteriae 1. Three successive oral administrations of LTSHΔstx to female adult mice produced comprehensive passive heterologous protection in their offspring against challenge with wild-type shigellae. Production of NO and different cytokines such asIL-12p70, IL-1ß and IL-23 in peritoneal mice macrophages indicated that LTSHΔstx induced innate and adaptive immunity in mice. Furthermore, production of IFN-γ, IL-10 and IL-17 in LTSH-primed splenic CD4+ T cell suggested that LTSHΔstx may induce Th1 and Th17 cell-mediated immune responses. Exponential increase of the serum IgG and IgA titre against whole shigellae was observed in immunized adult mice during and after the immunization with the highest peak on day 35. Antigen-specific sIgA was also determined from intestinal lavage of immunized mice. The stomach extracts of neonates from immunized mice, mainly containing mother's milk, contained significant levels of anti-LTSHΔstx immunoglobulin. These studies suggest that the LTSHΔstx could be a new live oral vaccine candidate against shigellosis in the near future.


Assuntos
Shigella/imunologia , Células Th1/imunologia , Células Th17/imunologia , Administração Oral , Animais , Animais Recém-Nascidos , Anticorpos Antibacterianos/biossíntese , Antígenos de Bactérias/genética , Vacinas Bacterianas/administração & dosagem , Vacinas Bacterianas/genética , Vacinas Bacterianas/imunologia , Conjugação Genética , Modelos Animais de Doenças , Disenteria Bacilar/imunologia , Disenteria Bacilar/microbiologia , Disenteria Bacilar/prevenção & controle , Feminino , Deleção de Genes , Genes Bacterianos , Imunidade Celular , Imunização Passiva , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Toxina Shiga/genética , Shigella/genética , Shigella/patogenicidade , Shigella dysenteriae/genética , Shigella dysenteriae/imunologia , Shigella dysenteriae/patogenicidade , Especificidade da Espécie , Vacinas Atenuadas/administração & dosagem , Vacinas Atenuadas/genética , Vacinas Atenuadas/imunologia , Virulência/genética
13.
Cell Mol Neurobiol ; 35(2): 197-204, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25212825

RESUMO

Docosahexaenoic acid (DHA), an omega-3 fatty acid family member, is obtained by diet or synthesized from dietary essential omega-3 linolenic acid and delivered systemically to the choriocapillaris, from where it is taken up by the retinal pigment epithelium (RPE). DHA is then transported to the inner segments of photoreceptors, where it is incorporated in phospholipids during the biogenesis of outer segment disk and plasma membranes. As apical photoreceptor disks are gradually shed and phagocytized by the RPE, DHA is retrieved and recycled back to photoreceptor inner segments for reassembly into new disks. Under uncompensated oxidative stress, the docosanoid neuroprotectin D1 (NPD1), a potent mediator derived from DHA, is formed by the RPE and displays its bioactivity in an autocrine and paracrine fashion. The purpose of this study was to determine whether photoreceptors have the ability to synthesize NPD1, and whether or not this lipid mediator exerts bioactivity on these cells. For this purpose, 661W cells (mouse-derived photoreceptor cells) were used. First we asked whether these cells have the ability to form NPD1 by incubating cells with deuterium (d4)-labeled DHA exposed to dark and bright light treatments, followed by LC-MS/MS-based lipidomic analysis to identify and quantify d4-NPD1. The second question pertains to the potential bioactivity of these lipids. Therefore, cells were incubated with 9-cis-retinal in the presence of bright light that triggers cell damage and death. Following 9-cis-retinal loading, DHA, NPD1, or vehicle were added to the media and the 661W cells maintained either in darkness or under bright light. DHA and NPD1 were then quantified in cells and media. Regardless of lighting conditions, 661W cells acquired DHA from the media and synthesized 4-9 times as much d4-NPD1 under bright light treatment in the absence and presence of 9-cis-retinal compared to cells in darkness. Viability assays of 9-cis-retinal-treated cells demonstrated that 34 % of the cells survived without DHA or NPD1. However, after bright light exposure, DHA protected 23 % above control levels and NPD1 increased protection by 32 %. In conclusion, the photoreceptor cell line 661W has the capability to synthesize NPD1 from DHA when under stress, and, in turn, can be protected from stress-induced apoptosis by DHA or NPD1, indicating that photoreceptors effectively contribute to endogenous protective signaling mediated by NPD1 under stressful conditions.


Assuntos
Citoproteção/efeitos da radiação , Ácidos Docosa-Hexaenoicos/biossíntese , Ácidos Docosa-Hexaenoicos/farmacologia , Luz , Estresse Oxidativo/efeitos da radiação , Células Fotorreceptoras Retinianas Cones/metabolismo , Animais , Linhagem Celular , Citoproteção/efeitos dos fármacos , Diterpenos , Camundongos , Estresse Oxidativo/efeitos dos fármacos , Retinaldeído
14.
Nanotechnology ; 26(40): 405705, 2015 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-26376675

RESUMO

High quality Fe/γ-Fe2O3 core/shell, core/void/shell, and hollow nanoparticles with two different sizes of 8 and 12 nm were synthesized, and the effect of morphology, surface and finite-size effects on their magnetic properties including the exchange bias (EB) effect were systematically investigated. We find a general trend for both systems that as the morphology changes from core/shell to core/void/shell, the magnetization of the system decays and inter-particle interactions become weaker, while the effective anisotropy and the EB effect increase. The changes are more drastic when the nanoparticles become completely hollow. Noticeably, the morphological change from core/shell to hollow increases the mean blocking temperature for the 12 nm particles but decreases for the 8 nm particles. The low-temperature magnetic behavior of the 12 nm particles changes from a collective super-spin-glass system mediated by dipolar interactions for the core/shell nanoparticles to a frustrated cluster glass-like state for the shell nanograins in the hollow morphology. On the other hand for the 8 nm nanoparticles core/shell and hollow particles the magnetic behavior is more similar, and a conventional spin glass-like transition is obtained at low temperatures. In the case of the hollow nanoparticles, the coupling between the inner and outer spin layers in the shell gives rise to an enhanced EB effect, which increases with increasing shell thickness. This indicates that the morphology of the shell plays a crucial role in this kind of exchange-biased systems.

15.
Langmuir ; 30(15): 4465-73, 2014 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-24678973

RESUMO

In this work, we demonstrate two important features that arise out of introducing a liquid-crystalline (LC) compound into the rotator phase matrix and the consequent competition between the anisometric segments of the LC moieties and the aliphatic units. First, we show that the change in the structural character of the mixed medium depends on which of the entities forms the minority concentration: in the case of this being the alkane, the two components of the binary system are nanophase segregated, whereas if the LC molecules are present in a small concentration, then the layered structure merely gets roughened without any segregation. The second and more significant result of the calorimetric and X-ray experiments, at low LC concentrations, is the induction of a rotator phase that leads to unusual phase sequence not reported hitherto. Possible scenarios for the molecular arrangement are discussed. A Landau model is also presented that explains some of the observed features.

16.
Phys Chem Chem Phys ; 16(11): 5066-70, 2014 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-24487648

RESUMO

This work reports on the use of an internal electrostatic field to facilitate charge separation at inorganic-organic interfaces, analogous to those in hybrid solar cells. Systematic charge transfer studies show that the donor-acceptor charge transfer rate is highly sensitive to the direction of the internal electric field.

17.
J Opt Soc Am A Opt Image Sci Vis ; 31(2): 379-87, 2014 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-24562037

RESUMO

Pupil plane filtering by radial Walsh filters is a convenient technique for tailoring the axial intensity distribution near the focal plane of a rotationally symmetric imaging system. Radial Walsh filters, derived from radial Walsh functions, form a set of orthogonal phase filters that take on values either 0 or π phase, corresponding to +1 or -1 values of the radial Walsh functions over prespecified annular regions of the circular filter. Order of these filters is given by the number of zero-crossings, or equivalently phase transitions within the domain over which the set is defined. In general, radial Walsh filters are binary phase zone plates, each of them demonstrating distinct focusing characteristics. The set of radial Walsh filters can be classified into distinct groups, where the members of each group possess self-similar structures. Self-similarity can also be observed in the corresponding axial intensity distributions. These observations provide valuable clues in tackling the inverse problem of synthesis of phase filter in accordance with prespecified axial intensity distributions. This paper reports our observations on self-similarity in radial Walsh filters of various orders and corresponding axial intensity distributions.

18.
Phys Rev Lett ; 111(24): 243201, 2013 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-24483657

RESUMO

We present an experimental determination of the 2p3d(1Po)→1s3d(1De) x-ray line emitted from He-like Si, S, and Cl projectile ions, excited in collisions with thin carbon foils, using a high-resolution bent-crystal spectrometer. A good agreement between the observation and state-of-the-art relativistic calculations using the multiconfiguration Dirac-Fock formalism including the Breit interaction and QED effects implies the dominance of fluorescent decay over the autoionization process for the 2p3d(^{1}P^{o}) state of He-like heavy ions. This is the first observation of the fluorescence-active doubly excited states in He-like Si, S, and Cl ions.

19.
Indian J Lepr ; 85(2): 59-64, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24236364

RESUMO

Secular trends in incidence of leprosy serve as a powerful tool in determining progress in reaching eradication. However, the interpretation of these trends must take into account both operational and epidemiological factors. A study was done to assess a time trend in the ratios of MB & PB from 2001 to 2010 based on the leprosy patients registered in a referral hospital in UP, India. Data were analyzed based on the gender, age and residence. Regardless of these factors, MB proportion shows no significant trends. These findings are discussed and it is concluded that we are no more close to eradication as compared to the status over a decade ago. Hence, much greater efforts will be required to promote early detections of MB cases, whether children or adults, male or female.


Assuntos
Hanseníase Multibacilar/epidemiologia , Hanseníase Paucibacilar/epidemiologia , Adulto , Criança , Feminino , Humanos , Índia/epidemiologia , Masculino , Estudos Retrospectivos , Centros de Atenção Terciária/estatística & dados numéricos
20.
Eur Phys J E Soft Matter ; 35(4): 9705, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22526979

RESUMO

Using the Landau model, the temperature and frequency dependence of the complex non-linear dielectric effect in the isotropic phase above the isotropic-smectic-A phase transition is calculated. Comparing the results of the calculations with existing data, we finally conclude that the model provides a description of the isotropic-smectic-A transition that takes all experimentally known features of the non-linear dielectric effect in the isotropic phase into account in a qualitatively correct way.


Assuntos
Cristais Líquidos/química , Modelos Químicos , Transição de Fase , Anisotropia , Simulação por Computador , Condutividade Elétrica , Temperatura
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