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1.
Sci Rep ; 14(1): 986, 2024 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-38200112

RESUMO

Transboundary pollutant transport is considered as one of the primary factors causing the seasonal air quality deterioration in Delhi, India's capital. The highest standard deviations exceeding days in winter for NO2 (7.14-9.63%) and SO2 (4.04-7.42%) in 2019-2022 underscore the role of meteorological conditions in Delhi's pollution. In contrast, the post-monsoon season shows the highest pollutant exceedance days (4.52-8.00%) for CO due to stubble burning (SB) in Punjab (68,902 fires/year). Despite the government's assertions of decreasing SB events (14.68%), the city's CO exceedance days persistently rose by 6.36%. CAMS data is used for assessing contribution hotspots through back-trajectory analysis at multiple heights. An overlap hotspot of 111 sq. km area is identified in the Southeast parts of Punjab that have a higher contribution to the CO levels in Delhi during the post-monsoon season of 2019. Similarly, hotspots are also observed for SO2 over industrial areas of Punjab during the post-monsoon and pre-monsoon seasons. The same seasons show similar contributing patterns for NO2 highlighting the influence of consistent emission patterns and meteorological conditions. The clear delineation of hotspots using the receptor model at multiple heights coupled with source apportionment studies will assist decision-makers in addressing the pollution sources outside Delhi.

2.
Protein J ; 42(6): 685-697, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37421558

RESUMO

The lack of specific antiviral therapy and complications associated with the existing peste des petits ruminants (PPR) vaccines accentuates the search of novel antiviral blocking agents in order to curtail the PPR infection at initial level. The synthetic hemagglutinin-neuraminidase (HN) homologous peptides may compete with the natural HN protein of PPR virus for binding to signaling lymphocytic activation molecule (SLAM) receptor, consequently, may disrupt peste des petits ruminants virus (PPRV) at entry level. Therefore, insilico analysis, synthesis, purification and subsequent characterization of HN homologous peptides were conducted in this study. The HN homologous peptides were synthesized by means of solid phase chemistry and were purified by reversed-phase-high performance liquid chromatography. The mass as well as sequence of HN homologous peptides were assessed by mass spectroscopy while its secondary structure was elucidated by circular dichroism spectroscopy. The binding (interaction) efficacy of HN homologous peptides with PPRV antibodies was assessed via indirect enzyme linked immunosorbent assay, visual detection test (red wine to purple), bathochromic shift under UV-Vis spectrophotometry and lateral flow immunochromatographic strip test. The antiviral properties and cytotoxicity of these peptides were also assessed in B95a cell line with changes in cytopathic effect and titer of PPRV (Sungri/96). The presence of green fluorescein isothiocyanate over the B95a cell surface pointed towards the binding of HN homologous peptides with surface SLAM receptor. Moreover, the intact beta sheet configuration in water and lower cytotoxicity [cytotoxic concentration 50 (CC50) > 1000 µg/ml] of these peptides signifies its in vivo use. Among HN homologous peptides, the binding efficacy and antiviral properties of pep A was relatively high in comparison to pep B and Pep ppr peptides. The prerequisite concentration of HN homologous peptides (pep A = 12.5 µg/ml; pep B = 25 µg/ml; pep ppr = 25 µg/ml) to exemplify its antiviral effect was much lower than its CC50 level. Hence, this study signifies the therapeutic potential of synthetic HN homologous peptides.

3.
Appl Radiat Isot ; 199: 110860, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37290268

RESUMO

A successful attempt was made to fabricate a thin foil of natural Mo target on a thick Au backing with Indium in between to improve adhesion between the foils. Rolling at elevated temperature was considered to fabricate Mo foil while gold foil was fabricated employing conventional rolling technique. The heating of Mo foil under natural environment lead to the oxidation or carbonization on foil surface which was confirmed through Energy Dispersive X-ray Spectroscopy (EDS) measurements. Indium of thickness ∼86µg/cm2 was evaporated on Mo foil to improve adhesion between Mo and Au foils. The characterization of fabricated thin Mo foil was done using the Energy Dispersive X-ray Spectroscopy (EDS) and the Scanning Electron microscope (SEM) techniques. Thickness measurement of the target (Mo-Au) was done using Energy Dispersive X-ray Fluorescence (EDXRF) technique, in the measurements the thickness of the Mo foil and of gold backing are found out to be 1.3 mg/cm2 and 9 mg/cm2 respectively.

4.
J Immunol Methods ; 514: 113438, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36738767

RESUMO

Canine distemper is an emerging disease, caused by the Canine morbillivirus (CDV) of the Paramyxoviridae family. The virus has evolved as a multi-host pathogen as it affects many wildlife animal species. The development of specific and sensitive diagnostic tests is the need for a control program. Several diagnostic tests are available for the detection of CDV antigen and antibody. Lateral flow assay (LFA) is the most promising point of care diagnostic test because of its specificity, easy use, and instant result. This study was designed to develop a lateral flow assay using the in-house developed monoclonal antibody (mAb) against the nucleocapsid protein (N) of the 'CDV/dog/bly/Ind/2018' isolate, which represents the circulating strains of India. The two mAbs included in the study showed high binding affinity in indirect ELISA and dot blot assay. Out of two, one mAb was selected due to its comparatively higher binding affinity in LFA format, and less non-specific binding to the biological matrix and buffer components. The limit of detection was found to be 106.5 TCID50/ml with the assay run time of 5 min. The fresh clinical samples collected on the spot were distinctly detected by the LFA, whereas the stored samples with a reduced titre of the virus showed inconsistent results. Moreover, the blood samples showed a clear distinction of positive and negative than the swab and tissue homogenates. The RNA extraction from the strip was successful with the some modifications in the Trizol RNA extraction method and the N and H gene fragments were amplified. Therefore, the study concludes that the LFA is suitable for CDV antigen detection in the field conditions and the strips can be used as the sample substitute for molecular study.


Assuntos
Vírus da Cinomose Canina , Cinomose , Animais , Cães , Vírus da Cinomose Canina/genética , Cinomose/diagnóstico , Proteínas do Nucleocapsídeo/genética , Anticorpos Antivirais , Anticorpos Monoclonais , RNA
5.
Int J Biol Macromol ; 215: 1-11, 2022 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-35718140

RESUMO

L-asparaginase, an antileukemic enzyme, is indispensable to the treatment of Acute Lymphoblastic Leukemia (ALL). However, the intrinsic glutaminase activity entails various side effects to the patients; thus, an improved version of the enzyme lacking glutaminase activity would be a requisite for effective treatment management of ALL. The present study highlights the biochemical and molecular characteristics of the recombinant glutaminase-free L-asparaginase from Bacillus australimaris NJB19 (BaAsp). Investigation of the active site architecture of the protein unraveled the binding interactions of BaAsp with its substrate. Comparative analysis of the L-asparaginase sequences revealed few substitutions of key amino acids in the BaAsp that could construe its substrate selectivity and specificity. The purified heterologously expressed protein (42 kDa) displayed maximum L-asparaginase activity at 35-40 °C and pH 8.5-9, with no observed L-glutaminase activity. The kinetic parameters, Km and Vmax, were determined as 45.6 µM and 0.16 µmoles min-1, respectively. Furthermore, in silico analysis revealed a conserved zinc-binding site in the protein, which is generally implicated in inhibiting the L-asparaginase activity. However, BaAsp was not inhibited by zinc at 1 mM concentration. Therefore, the findings provide insights on the biochemical and molecular details of BaAsp, which could be valuable in formulating it for alternate antileukemic drug therapy.


Assuntos
Antineoplásicos , Bacillus , Leucemia-Linfoma Linfoblástico de Células Precursoras , Antineoplásicos/química , Asparaginase/química , Humanos , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Especificidade por Substrato , Zinco
6.
J Opt Soc Am A Opt Image Sci Vis ; 39(4): 759-765, 2022 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-35471402

RESUMO

We present a speckle-based deep learning approach for orbital angular momentum (OAM) mode classification. In this method, we have simulated the speckle fields of the Laguerre-Gauss (LG), Hermite-Gauss (HG), and superposition modes by multiplying these modes with a random phase function and then taking the Fourier transform. The intensity images of these speckle fields are fed to a convolutional neural network (CNN) for training a classification model that classifies modes with an accuracy >99%. We have trained and tested our method against the influence of atmospheric turbulence by training the models with perturbed LG, HG, and superposition modes and found that models are still able to classify modes with an accuracy >98%. We have also trained and tested our model with experimental speckle images of LG modes generated by three different ground glasses. We have achieved a maximum accuracy of 96% for the most robust case, where the model is trained with all simulated and experimental data. The novelty of the technique is that one can do the mode classification just by using a small portion of the speckle fields because speckle grains contain the information about the original mode, thus eliminating the need for capturing the whole modal field, which is modal dependent.

8.
Br J Oral Maxillofac Surg ; 59(9): 1024-1030, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34563354

RESUMO

COVID-19 is a new disease that presents mainly with respiratory symptoms. However, it can present with a multitude of signs and symptoms that affect various body systems and several oral manifestations have also been reported. We carried out a systematic review to explore the types of oral mucosal lesions that have been reported in the COVID-19-related literature up to 25 March 2021. A structured electronic database search using Medline, Embase, and CINAHL, as well as a grey literature search using Google Scholar, revealed a total of 322 studies. After the removal of duplicates and completion of the primary and secondary filtering processes, 12 studies were included for final appraisal. In patients with COVID-19 infection, we identified several different types of oral mucosal lesions at various locations within the oral cavity. Most of the studies appraised had a high risk of bias according to the Joanna Briggs Institute checklist. The current published literature does not allow differentiation as to whether the oral lesions were caused by the viral infection itself, or were related to oral manifestations secondary to existing comorbidities or the treatment instigated to combat the disease. It is important for healthcare professionals to be aware of the possible link between COVID-19 and oral mucosal lesions, and we hereby discuss our findings.


Assuntos
COVID-19 , Úlceras Orais , Pessoal de Saúde , Humanos , SARS-CoV-2
9.
Br J Oral Maxillofac Surg ; 59(9): 1090-1094, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34454777

RESUMO

An increasing elderly population in the United Kingdom has led to an increasing number of older patients with head and neck cancer, resulting in a greater demand for complex head and neck reconstructive surgery in this potentially high-risk age group. A possible perceived poorer tolerance to such major treatment risks under-treating some of these patients. The purpose of this study was to assess the outcomes in the elderly population (older than 80 years) who had undergone free flap reconstruction following head and neck cancer resection. A retrospective review of 127 patients was performed. Eighteen patients were 80 or older (14.2%) and 109 under 80 (85.8%). The elderly group experienced increased number of postoperative medical complications (p=0.01), but the surgical complications were not significantly different in the two groups (p=0.4). The average length of hospital stay was significantly longer in the older group (p=0.01). There was one flap failure during the study period, which belonged to the younger group of patients. Elderly patients undergoing free flap reconstruction experience an increased rate of postoperative medical complications resulting in an increased length of hospital stay. However, good surgical outcomes can still be achieved in this age group, and therefore age alone should not be considered as a primary factor in head and neck cancer management.


Assuntos
Retalhos de Tecido Biológico , Neoplasias de Cabeça e Pescoço , Procedimentos de Cirurgia Plástica , Idoso , Idoso de 80 Anos ou mais , Neoplasias de Cabeça e Pescoço/cirurgia , Humanos , Tempo de Internação , Complicações Pós-Operatórias/epidemiologia , Estudos Retrospectivos , Resultado do Tratamento
11.
Br J Oral Maxillofac Surg ; 59(6): 716-719, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33975765

RESUMO

We previously published a study on the provision of emergency maxillofacial services during the first UK COVID-19 pandemic national lockdown. We repeated the study during the second lockdown and now present our findings that highlight the main differences and learning issues as the services have evolved.


Assuntos
COVID-19 , Pandemias , Controle de Doenças Transmissíveis , Humanos , SARS-CoV-2 , Reino Unido
12.
Lett Appl Microbiol ; 72(5): 570-577, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33474743

RESUMO

Effect of rhizobial inoculation and nitrate application on the content of bioactive compounds in legume plants is an interesting aspect for interactions among microbes, plants and chemical fertilizers, as well as for cultivated practice of legumes. In this study, nitrate (0, 5 and 20 mmol l-1 ) and Bradyrhizobium arachidis strain CCBAU 051107T were applied, individually or in combination, to the root rhizosphere of the medicinal legume Sophora flavescens Aiton (SFA). Then the plant growth, nodulation and active ingredients including (oxy)matrine of SFA were determined and compared. Rhizobial inoculation alone significantly increased the numbers and fresh weight of root nodules. Nodulation was significantly inhibited due to nitrate (5 and 20 mmol l-1 ). Only oxymatrine was detected in the control plants without rhizobial inoculation and nitrate supplement, while both oxymatrine and matrine were synthesized in plants treated with inoculation of B. arachidis or supplied with nitrate. The content of oxymatrine was the highest in plants inoculated solely with rhizobia and was not significantly altered by additional application of nitrate. Combinations of B. arachidis inoculation and different concentrations of nitrate did not significantly change the concentrations of (oxy)matrine in the plant. In conclusion, sole rhizobial inoculation was the best approach to increase the contents of key active ingredients oxymatrine and matrine in the medicinal legume SFA.


Assuntos
Alcaloides/análise , Bradyrhizobium/metabolismo , Nodulação/fisiologia , Raízes de Plantas/microbiologia , Quinolizinas/análise , Fertilizantes/análise , Nitratos/farmacologia , Rizosfera , Sophora/química , Sophora/microbiologia , Simbiose/fisiologia , Verduras , Matrinas
13.
J Phys Condens Matter ; 33(13)2021 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-33406510

RESUMO

Recently topological semimetals emerge as a new platform to realise topological superconductivity. Here we report the emergent superconductivity in single-crystals of Re doped type-II Weyl semimetal NiTe2. The magnetic and transport measurements highlight that Re substitution in Ni-site induces superconductivity at a maximum temperature of 2.36 K. Hall effect and specific heat measurements indicate that Re substitution is doping hole and facilitates the emergence of superconductivity by phonon softening and enhancing the electron-phonon coupling.

14.
Int J Biol Macromol ; 174: 527-539, 2021 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-33508362

RESUMO

L-asparaginase is a cardinal biotherapeutic drug for treating acute lymphoblastic leukemia, which is highly prevalent in children worldwide. In the current investigation, L-asparaginase producing marine bacterial isolate, Bacillus australimaris NJB19 (MG734654), was observed to be producing extracellular glutaminase free L-asparaginase (13.27 ± 0.4 IU mL-1). Production of L-asparaginase was enhanced by the Box-Behnken design approach that enumerated the significant variables affecting the enzyme production. The optimum levels of the derived variables resulted in 2.8-fold higher levels of the enzyme production (37.93 ± 1.06 IU mL-1). An 1146 bp L-asparaginase biosynthetic gene of Bacillus australimaris NJB19 was identified and cloned in E. coli DH5α, fused with a histidine tag. The in silico analysis of the protein sequence revealed the presence of a signal peptide and classified it as a type II L-asparaginase. Toxic peptide prediction disclosed no toxin domain in the protein sequence, hence suggesting it as a non-toxic protein. The secondary structure analysis of the enzyme displayed a comparable percentage of alpha-helical and random coil structure, while 14.39% and 6.57% of amino acid residues were composed of extended strands and beta-turns, respectively. The functional sites in the three-dimensional structural model of the protein were predicted and interestingly had a few less conserved residues. Bacillus australimaris NJB19 identified in this study produces type-II L-asparaginase, known for its high affinity for asparagine and effectiveness against leukemic cells. Hence, these observations indicate the L-asparaginase, thus obtained, as a potentially significant and novel therapeutic drug.


Assuntos
Asparaginase/química , Asparaginase/metabolismo , Bacillus/enzimologia , Clonagem Molecular/métodos , Sequência de Aminoácidos , Asparaginase/genética , Asparagina/metabolismo , Bacillus/classificação , Bacillus/genética , Bacillus/isolamento & purificação , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Simulação por Computador , Escherichia coli/genética , Escherichia coli/crescimento & desenvolvimento , Sedimentos Geológicos/microbiologia , Modelos Moleculares , Filogenia , Estrutura Secundária de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo
15.
Saudi J Kidney Dis Transpl ; 32(6): 1646-1654, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-35946277

RESUMO

Emphysematous pyelonephritis (EPN) is a rare but life-threatening acute suppurative infection of the kidney among diabetics. There is no current consensus on the management of EPN. A prospective observational study was conducted at the Department of General Surgery, RML Institute of Medical Sciences, Lucknow, as well as at Eras Lucknow Medical College, Lucknow, from 2015 to 2018 to look for clinical, microbial profile and treatment outcome of diabetic patients with EPN. A total of 76 diabetic patients diagnosed with pyelonephritis were identified, of which 15 patients were diagnosed with EPN (26.3%). The mean age of the patients was 58.4 ± 6.5 years. The mean duration of diabetes was 5.3 ± 3.3 years. 12 (82%) of the 15 patients with diabetes mellitus had a glycosylated hemoglobin level higher than 7.5. Renal dysfunction at presentation was seen in 11 (73.3%) patients. Among the unilateral involvement, the left kidney was more affected. Escherichia coli in 11 (73.3%), Klebsiella sp. in one (6.6%), Pseudomonas in one (6.6%), and one each with polymicrobial and fungal urinary tract infection, respectively. Of 15 EPN patients, 13 (86.6 %) survived, and one (6.6 %) expired. Two of them underwent nephrectomy both survived. All patients with Stage I, II, and IIIa EPN (n = 12) were managed with antibiotics with or without percutaneous catheter drainage (PCD). In EPN Stage IIIb/IV (n = 3), all the three (20%) patients were managed with antibiotics and PCD, and later two (13.3%) needed nephrectomy. Only time to diagnosis, altered sensorium, shock at presentation, and thrombocytopenia were associated with poor outcome in EPN patients (P <0.05) Multiple logistic regression tests showed shock (P = 0.04) and disturbance of consciousness (P = 0.05) on (hospital admission as being the independent factors for poor outcome. EPN in diabetics needs a high index of suspicion, timely diagnosis, and good multidisciplinary approach with adequate antibiotics and surgical management for better patient outcomes.


Assuntos
Complicações do Diabetes , Diabetes Mellitus Tipo 2 , Enfisema , Pielonefrite , Antibacterianos/uso terapêutico , Complicações do Diabetes/complicações , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/tratamento farmacológico , Enfisema/complicações , Enfisema/diagnóstico , Enfisema/terapia , Escherichia coli , Humanos , Pessoa de Meia-Idade , Pielonefrite/complicações , Pielonefrite/diagnóstico , Pielonefrite/terapia
16.
Int J Biol Macromol ; 167: 934-946, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33189758

RESUMO

Bone repair using BMP-2 is a promising therapeutic approach in clinical practices, however, high dosages required to be effective pose issues of cost and safety. The present study explores the potential of low dose BMP-2 treatment via tissue engineering approach, which amalgamates 3-D macro/microporous-nanofibrous bacterial cellulose (mNBC) scaffolds and low dose BMP-2 primed murine mesenchymal stem cells (C3H10T1/2 cells). Initial studies on cell-scaffold interaction using unprimed C3H10T1/2 cells confirmed that scaffolds provided a propitious environment for cell adhesion, growth, and infiltration, owing to its ECM-mimicking nano-micro-macro architecture. Osteogenic studies were conducted by preconditioning the cells with 50 ng/mL BMP-2 for 15 min, followed by culturing on mNBC scaffolds for up to three weeks. The results showed an early onset and significantly enhanced bone matrix secretion and maturation in the scaffolds seeded with BMP-2 primed cells compared to the unprimed ones. Moreover, mNBC scaffolds alone were able to facilitate the mineralization of cells to some extent. These findings suggest that, with the aid of 'osteoinduction' from low dose BMP-2 priming of stem cells and 'osteoconduction' from nano-macro/micro topography of mNBC scaffolds, a cost-effective bone tissue engineering strategy can be designed for quick and excellent in vivo osseointegration.


Assuntos
Proteína Morfogenética Óssea 2/farmacologia , Celulose/química , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/efeitos dos fármacos , Nanofibras/química , Polissacarídeos Bacterianos/química , Engenharia Tecidual , Alicerces Teciduais , Fator de Crescimento Transformador beta/farmacologia , Animais , Osso e Ossos , Calcificação Fisiológica , Diferenciação Celular , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Fenômenos Químicos , Camundongos , Nanofibras/ultraestrutura , Osteogênese/efeitos dos fármacos , Proteínas Recombinantes/farmacologia , Termogravimetria , Difração de Raios X
17.
Appl Spectrosc ; 74(8): 913-920, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32602354

RESUMO

Stark broadening parameters have been estimated for resonant lines of Al(I) using time resolved measurements. The relation between the various emission line characteristics at different phases of opacity have been utilized to obtain the value of plasma temperature and Stark width parameters from the experimental data. The observed value of the center line intensity and Lorentzian component of the line width are compared against a simulated value of these parameters for optically thin case. The plasma temperature and Stark broadening parameters are obtained for the best fit condition by matching the experimentally observed and the simulated values of intensity and line widths. The time resolved measurements result in much better estimates for Stark parameters by allowing multiple points for fitting keeping the number of variables limited. The Stark shift parameters are also obtained from the slope of the plot of observed central wavelength shifts versus observed electron number density which is measured as a function of time. Hence, a method utilizing multiple-time observation data to obtain the Stark broadening parameters for lines showing self-absorption has been demonstrated.

18.
Br J Oral Maxillofac Surg ; 58(6): 698-703, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32482348

RESUMO

The global pandemic of Coronavirus disease (COVID-19) represents one of the greatest challenges to healthcare systems, and has forced medical specialties to rapidly adapt their approaches to patient care. Oral and Maxillofacial Surgery is considered particularly at risk of disease transmission due to aerosol generation during surgical interventions, patient proximity and operating environment. On day 2 (26th March, 2020) of when severe restrictions in population movement were instigated in the United Kingdom, we began a study to prospectively monitor the presentation and management of maxillofacial emergencies at five hospital trusts. Data was collected onto an online live database fed through a smartphone application. Of the total 529 patients over six weeks, 395 attended for face-to-face consultations and 134 patients received remote consultations via telephone or video link. There were 255 trauma related cases, 221 infection and 48 cases of postoperative complications. Most trauma cases were minor soft tissue injury related to slip, trip or fall at home. There were 44 cases of facial fractures with a tendency for conservative treatment. 19 cases were related to domestic violence or self-harm. Of the 216 dental related emergencies, 68% could have been managed in the primary care setting. A quarter of all emergency patients were satisfactorily managed by remote consultations. There was a significant change in the provision of emergency maxillofacial service during the pandemic lockdown. We discuss the study findings as well as the potential implications in relation to planning for possible further COVID- 19 spikes and future pandemics.


Assuntos
Betacoronavirus , Infecções por Coronavirus , Pandemias , Pneumonia Viral , COVID-19 , Infecções por Coronavirus/epidemiologia , Feminino , Humanos , Masculino , Pneumonia Viral/epidemiologia , SARS-CoV-2 , Reino Unido/epidemiologia
20.
J Opt Soc Am A Opt Image Sci Vis ; 37(5): 780-786, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32400711

RESUMO

Far-field slit diffraction of circular optical-vortex (OV) beams is efficient for measurement of the topological charge (TC) magnitude but does not reveal its sign. We show that this is because in the common diffraction schemes the diffraction plane coincides with the incident OV waist plane. Based on the examples of Laguerre-Gaussian incident beams containing a spherical wavefront component, we demonstrate that the far-field diffracted beam profile possesses an asymmetry depending on the incident wavefront curvature and the TC sign. This finding enables simple and efficient ways for the simultaneous diagnostics of the TC magnitude and sign, which can be useful in many OV applications, including OV-assisted metrology and information processing.

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