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1.
J Phys Condens Matter ; 34(3)2021 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-34598178

RESUMO

We probe quantum oscillations in nodal line semimetals (NLSM) by considering an NLSM continuum model under strong magnetic field and report the characteristics of the Landau level (LL) spectra and the fluctuations in the Fermi level as the field in a direction perpendicular to the nodal plane is varied through. Based on the results on parallel magnetization, we demonstrate the growth of quantum oscillation with field strength as well as its constancy in period when plotted against 1/B. We find that the density of states (DOS) which show series of peaks in succession, witness bifurcation of those peaks due to Zeeman effect. For field normal to nodal plane, such bifurcations are discernible only if the electron effective mass is considerably smaller than its free value, which usually happens in these systems. Though a reduced effective massm* causes the Zeeman splitting to become small compared to LL spacings, experimental results indicate a manifold increase in the Landegfactor which again amplifies the Zeeman contribution. We also consider magnetic field in the nodal plane for which the DOS peaks do not repeat periodically with energy anymore. The spectra become more spread out and the Zeeman splittings become less prominent. We find the low energy topological regime, that appears with such in-plane field set up, to shrink further with reducedm* values. However, such topological regime can be stretched out in case there are smaller Fermi velocities for electrons in the direction normal to the nodal plane.

2.
Artigo em Inglês | MEDLINE | ID: mdl-35010473

RESUMO

AIM: To assess the knowledge and perceptions of COVID-19 among pediatric dentists based on their dependent source of information. METHODS: A descriptive-analytical cross-sectional survey using a self-administered questionnaire with 23 questions was sent via Google forms to pediatric dentists. All participants were divided into three groups [postgraduate residents (PGs), private practitioners (PP), and faculty (F)]. The comparison of knowledge and perception scores was made based on occupation, source of information, and descriptive statistics used for the analysis using SPSS 21.0 (IBM, Armonk, NY, USA). RESULTS: A total of 291 pediatric dentists completed the survey, and the majority of them were females (65%). Overall, good mean scores were obtained for knowledge (9.2 ± 1.07) and perceptions (5.6 ± 1.5). The majority of the participants used health authorities (45%) to obtain updates on COVID-19, while social media (35.1%) and both (19.6%) accounted for the next two. A statistically significant difference (p < 0.05) was found among different pediatric dentists groups for relying on the source of information. CONCLUSION: Overall good pediatric dentists showed sufficient knowledge regarding COVID-19. The pediatric dentists' age, occupation, and source of information influenced knowledge regarding COVID-19, whereas perceptions were influenced by age and gender of the participants. Health authorities successfully educated pediatric dentists than the social media.


Assuntos
COVID-19 , Criança , Controle de Doenças Transmissíveis , Estudos Transversais , Odontólogos , Feminino , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Padrões de Prática Odontológica , SARS-CoV-2 , Inquéritos e Questionários
3.
Langmuir ; 34(42): 12653-12663, 2018 10 23.
Artigo em Inglês | MEDLINE | ID: mdl-30265540

RESUMO

The synthesis of a series of dual thermosensitive nonionic-ionic random copolymers with varying compositions by reversible addition-fragmentation chain transfer polymerization is described. These copolymers contain oligo(2-ethyl-2-oxazoline)acrylate (OEtOxA) and either triphenyl-4-vinylbenzylphosphonium chloride ([VBTP][Cl]) or 3- n-butyl-1-vinylimidazolium bromide ([VBuIm][Br]) ionic liquid (IL) units. The copolymers having low content of ionic poly(ionic liquid) (PIL) (P[VBTP][Cl]/P[VBuIm][Br]) segments show only lower critical solution temperature (LCST)-type phase transition with almost linear increase of their cloud points with increasing percentage of ionic PIL segments. Furthermore, LCST-type cloud points ( TcLs) are found very sensitive and tunable with respect to the nature and concentration of halide ions (X- = Cl-, Br-, and I-) and copolymer compositions. However, copolymers with high content of ionic PIL segments show both LCST-type followed by upper critical solution temperature (UCST)-type phase transitions in the presence of halide ions. Dual LCST- and UCST-type phase behaviors are prominent and repeatable for many heating/cooling cycles. Both types of cloud points are found to be sensitive to copolymer compositions, concentration, and nature and concentration of the halide ions. The phase behaviors of both types of copolymers with a very high ionic content (>90%) are exactly similar to that of P[VBTP][Cl] or P[VBuIm][Br] homopolymers showing only UCST-type phase transition in the presence of halide ions. The inherent biocompatibility of the P(OEtOxA) segment along with the interesting dual thermoresponsiveness makes these copolymers highly suitable candidates for biomedical applications including drug delivery.

4.
J Phys Chem B ; 120(4): 813-24, 2016 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-26735171

RESUMO

We report on the synthesis of photocleavable poly(2-ethyl-2-oxazoline)-block-poly(2-nitrobenzyl acrylate) (PEtOx-b-PNBA) block copolymers (BCPs) with varying compositions via combination of microwave-assisted cationic ring-opening polymerization (CROP) and atom transfer radical polymerization (ATRP) using α-bromoisobutyryl bromide as an orthogonal initiator. The amphiphilic nature of this BCP causes them to self-assemble into primary micelles in THF/H2O, which further undergo secondary aggregation into nanostructured compound micelles as established through DLS, FESEM, and TEM. Upon UV irradiation (λ = 350 nm), the photocleavage of the PNBA block of the PEtOx-b-PNBA BCP takes place, and that leads to the formation of the doubly hydrophilic poly(2-ethyl-2-oxazoline)-b-poly(acrylic acid) (PEtOx-b-PAA) BCP causing the rupture of compound micelles as confirmed by spectroscopic and microscopic techniques. Encapsulation of a model hydrophobic guest molecule, nile red (NR), into the photocleavable BCP micellar core in aqueous solution and its UV-induced release is also investigated by fluorescence emission measurements. PEtOx-b-PNBA BCP amphiphiles are also shown to self-assemble into spherical nanostructures (∼90 nm) in dichloromethane as established by DLS and TEM analysis. These are referred to as reverse micelles and are able to encapsulate anionic hydrophilic dye, Eosin B, and facilitate its solubilization in organic media.

5.
Macromol Biosci ; 14(7): 929-35, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24687698

RESUMO

A fluorescent amphiphilic poly(ethylene glycol)-peptide-fluorophore-peptide-poly(ethylene glycol) (PEG-Pep-F-Pep-PEG) triblock conjugate with a hydrophobic fluorophore moiety at the centre of the chain is synthesized by "grafting to" technique based on Schiff-base coupling chemistry. The conjugate is characterized by nuclear magnetic resonance (NMR), circular dichroism (CD), and fluorescence spectroscopy techniques. The aqueous solution of the triblock conjugate emits blue light and exhibits a fluorescence emission band at 430 nm. The amphiphilic conjugate molecules undergo self-assembly into micelles (D ≈ 15-20 nm) in aqueous solution as confirmed from transmission electron microscopy (TEM) and dynamic light scattering (DLS). The critical aggregation concentration is determined by pyrene fluorescence assay and is found to be 0.051 mg mL(-1) . The highly stable and low toxic fluorescent PEG-Pep-F-Pep-PEG conjugate micelles are used for imaging of HeLa cells.


Assuntos
Micelas , Imagem Molecular/métodos , Polietilenoglicóis/química , Tensoativos/química , Células HeLa , Humanos , Microscopia Eletrônica de Transmissão , Polietilenoglicóis/síntese química , Soluções , Espectrometria de Fluorescência , Espectrofotometria Ultravioleta
6.
Indian J Gastroenterol ; 33(2): 136-40, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23999685

RESUMO

INTRODUCTION: Orthotopic liver transplantation has become a routinely applied therapy for an expanding group of patients with end-stage liver disease. Shortage of organs has led centers to expand their criteria for the acceptance of marginal donors. There is current debate about the regulation and results of liver transplantation using marginal grafts. METHODS: The study included data of all patients who received deceased donor liver grafts between March 2007 to December 2011. Patients with acute liver failure, living donor transplantation, split liver transplantation, and retransplantation were excluded. Early allograft dysfunction, primary nonfunction, patient survival, and incidence of surgical complications were measured. RESULTS: A total of 33 patients were enrolled in this study. There were 20 marginal and 13 nonmarginal grafts. The two groups were well matched regarding age, sex and indication of liver transplantation, model for end-stage liver disease score, technique of transplant, requirement of vascular reconstruction, warm ischemia time, blood loss, mean operative time, etc. In our study, posttransplant peak level of liver enzymes, international normalization ratio, and bilirubin were not statistically significant in the marginal and nonmarginal group. Wound infection occurred in 10 % of marginal compared with 7.7 % of nonmarginal graft recipients (p > 0.05). In the marginal group, the incidences of vascular complications, hepatic artery thrombosis (four), and portal vein thrombosis (one) were not statistically significant compared to the nonmarginal group. Acute rejection was observed in a total of seven patients (21.2 %)-five (25 %) in the marginal group and two (15.4 %) in the nonmarginal graft recipients. Primary nonfunction occurred in three (9.1 %) patients-two (10 %) in the marginal and one (7.7 %) in the nonmarginal group. Average patient survival for the whole group was 91 % at 1 week, 87.8 % at 3 months, and 84.8 % at 6 months. CONCLUSION: Because organ scarcity persists, additional pressure will build to use a greater proportion of the existing donor pool. The study, although small, clearly indicates that marginal livers can assure a normal early functional recovery after transplantation.


Assuntos
Doença Hepática Terminal/cirurgia , Transplante de Fígado/métodos , Disfunção Primária do Enxerto/diagnóstico , Obtenção de Tecidos e Órgãos/métodos , Adulto , Idoso , Feminino , Sobrevivência de Enxerto , Humanos , Fígado/fisiologia , Fígado/fisiopatologia , Masculino , Pessoa de Meia-Idade , Seleção de Pacientes , Disfunção Primária do Enxerto/etiologia , Recuperação de Função Fisiológica , Doadores de Tecidos/provisão & distribuição , Resultado do Tratamento , Adulto Jovem
7.
Med J Armed Forces India ; 68(2): 110-7, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24669047

RESUMO

BACKGROUND: This study retrospectively analyses the initial experience of liver transplantation (LT) in the Indian Armed Forces. METHODS: Fifty-three patients underwent LT at Army Hospital (R&R) Delhi Cantt. between March 2007 and March 2011. Of these 35 patients underwent deceased donor liver transplantation (DDLT) and living donor liver transplantation (LDLT) was carried out in 18 patients. The surgical techniques, complications and mortality were analysed. RESULTS: A high consent rate of 35.9% for organ donation was achieved by the Armed Forces Organ Retrieval and Transplantation Authority (AORTA). Biliary complications occurred in five patients (9.4%). However, most of them could be managed by endoscopic interventions. Hepatic artery thrombosis (HAT) occurred in five patients (9.4%). Of these, two DDLT grafts were revascularised following HAT, by creating extra-anatomic arterial conduits with excellent outcome. The overall mortality was 18.8% (n = 10). There was no significant difference in the overall complications or mortality in patients undergoing DDLT or LDLT. CONCLUSION: The overall survival and morbidity in this study is comparable to those from other centres. Urgent revascularisation of grafts following HAT should be attempted as it can salvage grafts with satisfactory outcome. There is a reduction in the incidence of biliary complications with refinements in surgical techniques.

9.
Liver Transpl ; 15(11): 1443-7, 2009 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-19877266

RESUMO

Organ donation following brain stem death is infrequent in India. There is no prospective study on prevalence of brain stem death and causes of non-donation. Consecutive patients admitted to intensive care unit from Sep 2006 to Sep 2008 were studied prospectively. Families of those with brain stem death were approached for organ donation by transplant coordinator. Extensive awareness drive was launched. Reasons for non-donation, if any, were documented. Of 2820 patients admitted, 994 (35%) were on mechanical ventilator and 657 (23%) died. Brain stem death could be diagnosed in 55, 37 males, median age 46 years (range 7 to 87 years) i.e., 1.9% of all admissions and 8.3% of all deaths. Among neurology and neurosurgery patients brain stem death was seen in 45 of 1037 (4.3%) admissions and 45 of 161 (27.9%) deaths. Complications of brain stem death were hypotension in 49, diabetes insipidus in 17 and hypertension in 5 patients. Of 33 families counselled, 16(48%) consented to organ donation. In 14(42%), organs and tissues retrieved and transplanted included 13 livers, 23 kidneys, 25 corneas and 5 cardiac valves. Consent was more likely in females (10 of 14 as compared to 6 of 19 males, p = 0.037). Consent did not correlate with age of donor or medico-legal issues (p = 0.227 & 0.579 respectively). Trained staff with requisite systems in place produced significant organ donation rates. Religious issues and medico legal concerns were not a major hurdle towards organ donation. Female patients with brain stem were more likely to become organ donors.


Assuntos
Atitude Frente a Morte/etnologia , Morte Encefálica , Recusa de Participação/etnologia , Obtenção de Tecidos e Órgãos/estatística & dados numéricos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Tronco Encefálico , Criança , Feminino , Humanos , Índia/epidemiologia , Unidades de Terapia Intensiva/estatística & dados numéricos , Masculino , Pessoa de Meia-Idade , Prevalência , Estudos Prospectivos , Recusa de Participação/psicologia , Recusa de Participação/estatística & dados numéricos , Adulto Jovem
11.
J Cytol ; 26(2): 55-9, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21938153

RESUMO

BACKGROUND: Computed tomography (CT)-guided fine needle aspiration cytology (FNAC) is regarded as a rapid, safe, and accurate diagnostic tool in examining thoracic mass lesions for the last three decades. AIMS: To assess the role of CT-guided FNAC in thoracic mass lesions, to analyse the results, and to compare the results with other studies. MATERIALS AND METHODS: Fifty-seven patients were studied over a year (July 2007 to June 2008) for their age, sex, and topographic distribution, pleural infiltration (based on CT findings), and cytological diagnoses. RESULTS: Out of 57 cases, 78.9% (n = 45) were male and 21.1% (n = 12) were female. The age range varied from 34 to 79 years with the peak in the fifth decade. There were 54 parenchymal (lung) tumors and the remaining three tumor cases were mediastinal. The most common tumor was squamous cell carcinoma (42.6%) followed by adenocarcinoma (29.6%) and small cell carcinoma. Postprocedural complications were minimal and were noted in only three cases (a little pulmonary hemorrhage in two and hemoptysis in one). CONCLUSIONS: CT-guided FNAC of thoracic mass lesions provides a rapid and safe diagnostic procedure with minimal complications. The categorical diagnosis can also be achieved on the basis of cytomorphology. The figures obtained from this study are comparable with other studies except for a few differences.

12.
J Gastroenterol Hepatol ; 20(5): 777-83, 2005 May.
Artigo em Inglês | MEDLINE | ID: mdl-15853994

RESUMO

BACKGROUND: With induction of Indian Army to heights over 5000 m above mean sealevel (MSL), several new complications of long-term stay at extreme altitude have come to light. The authors' experience with soldiers who developed symptomatic portal system thrombosis (SPST) is described here. METHODS: Clinical data were prospectively collected between April 1998 and April 2003, on all patients hospitalized for SPST from high-altitude areas (HAA, >3000 m above MSL) and those from non-high-altitude areas (NHAA). Site of thrombosis was confirmed by imaging and included splenic, portal, superior mesenteric, or inferior mesenteric vein thrombosis. Patients were investigated to rule out known predisposing factors and prothrombotic conditions. RESULTS: A total of 37 cases of SPST were seen during the study period, of which 26 were from HAA. Mean age of cases from HAA was 27 +/- 4.6 years and all were male. Mean stay at high altitude was 11.7 +/- 6.2 months. First symptom was pain in abdomen in almost all the cases, later followed by gastrointestinal bleeding and fever in 14 each, and vomiting in 19. Clinical examination showed ascites (81%), splenomegaly (76.9%), and hepatomegaly (69.2%). Diagnosis was made by imaging scans (23 cases) and on surgery in three cases. A known prothrombotic state was detected in five cases from HAA and in eight cases from NHAA (P < or = 0.01). Ultrasound Doppler scan picked up collaterals as early as 12-45 days after onset of symptoms. CONCLUSIONS: Extended stay at HAA may be a risk factor for development of symptomatic portal system thrombosis.


Assuntos
Altitude , Militares , Sistema Porta , Trombose Venosa/etiologia , Adulto , Testes de Coagulação Sanguínea , Estudos de Casos e Controles , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de Risco , Fatores de Tempo , Trombose Venosa/sangue , Trombose Venosa/diagnóstico
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