AIM Toll like receptors plays a significant anti-viral role in different infections. The aim of this study was to look into the role of toll like receptor 4(TLR4) in hepatitis B virus(HBV) infection.METHODS Real time ...AIM Toll like receptors plays a significant anti-viral role in different infections. The aim of this study was to look into the role of toll like receptor 4(TLR4) in hepatitis B virus(HBV) infection.METHODS Real time PCR was used to analyze the transcription of TLR4 signaling molecules, cell cycle regulators and HBV DNA viral load after triggering the Hep G2.2.15 cells with TLR4 specific ligand. Nuclear factor(NF)-κB translocation on TLR4 activation was analyzed using microscopic techniques. Protein and cell cycle analysis was done using Western Blot and FACS respectively.RESULTS The present study shows that TLR4 activation represses HBV infection. As a result of HBV suppression, there are several changes in host factors which include partial release in G1/S cell cycle arrest and changes in host epigenetic marks. Finally, it was observed that anti-viral action of TLR4 takes place through the NF-κB pathway.CONCLUSION The study shows that TLR4 activation in HBV infection brings about changes in hepatocyte microenvironment and can be used for developing a promising therapeutic target in future.展开更多
Medicinal plants, vegetables and fruits are the sources of huge number of bioactive lead/scaffolds with therapeutic and nutraceutical importance. Bioautography is a means of target-directed isolation of active molecul...Medicinal plants, vegetables and fruits are the sources of huge number of bioactive lead/scaffolds with therapeutic and nutraceutical importance. Bioautography is a means of target-directed isolation of active molecules on chromatogram. Organic solvents employed in chromatographic separation process can be completely removed before biological detection because these solvents cause inactivation of enzymes and/or death of living organisms. They offer a rapid and easy identification of bioactive lead/scaffolds in complex matrices of plant extracts. Bioautography is a technique to isolate hit（s）/lead（s） by employing a suitable chromatographic process followed by a biological detection system. This review critically describes the methodologies to identify antimicrobial, antioxidant, enzyme inhibitor lead/scaffolds by employing bioautography. A significant number of examples have been incorporated to authenticate the methodologies.展开更多
Very small nickel oxide nanoparticles were prepared by a sol-gel procedure using nickel nitrate hexahydrate and ammonium hydroxide as precursors. The particles are in the range of 5 nm-11 rim. The x-ray diffraction （...Very small nickel oxide nanoparticles were prepared by a sol-gel procedure using nickel nitrate hexahydrate and ammonium hydroxide as precursors. The particles are in the range of 5 nm-11 rim. The x-ray diffraction （XRD） crystallography and high resolution transmission electron microscopy （HRTEM） were employed to characterize the samples. They were found to be polycrystalline in nature and fcc （NaCl-type） in structure, with the lattice parameter varying with annealing temperature. HRTEM pictures show that the as-prepared samples are hexagonal in shape. Positron annihilation spectroscopy was used to investigate the Doppler-broadened spectra of the samples. The S and W parameters revealed that the chemical surroundings and momentum distribution of the vacancy clusters vary with crystallite size.展开更多
Nanocrystalline samples of highly pure lead oxide were prepared by the sol-gel route of synthesis.X-ray diffraction and transmission electron microscopic techniques confirmed the nanocrystallinity of the samples,and t...Nanocrystalline samples of highly pure lead oxide were prepared by the sol-gel route of synthesis.X-ray diffraction and transmission electron microscopic techniques confirmed the nanocrystallinity of the samples,and the average sizes of the crystallites were found within 20 nm to 35 nm.The nanocrystallites exhibited specific anomalous properties,among which a prominent one is the increased lattice parameters and unit cell volumes.The optical band gaps also increased when the nanocrystallites became smaller in size.The latter aspect is attributable to the onset of quantum confinement effects,as seen in a few other metal oxide nanoparticles.Positron annihilation was employed to study the vacancy type defects,which were abundant in the samples and played crucial roles in modulating their properties.The defect concentrations were significantly larger in the samples of smaller crystallite sizes.The results suggested the feasibility of tailoring the properties of lead oxide nanocrystallites for technological applications,such as using lead oxide nanoparticles in batteries for better performance in discharge rate and resistance.It also provided the physical insight into the structural build-up process when crystallites were formed with a finite number of atoms,whose distributions were governed by the site stabilization energy.展开更多
Steady state and time resolved fluorescence spectroscopy, combined with molecular dynamics simulation, have been used to explore the interactions of a therapeutically important bioflavonoid, genistein, with normal hum...Steady state and time resolved fluorescence spectroscopy, combined with molecular dynamics simulation, have been used to explore the interactions of a therapeutically important bioflavonoid, genistein, with normal human hemoglobin (HbA). Binding constants estimated from the fluorescence studies were K = (3.5 ± 0.32) ×104M-1 for genistein. Specific interactions with HbA were confirmed from flavonoid-induced fluorescence quenching of the tryptophan in the protein HbA. The mechanism of this quenching involves both static and dynamic components as indicated by: (a) increase in the values of Stern-Volmer quenching constants with temperatures, (b) / is slightly > 1 (where and are the unquenched and quenched tryptophan fluorescence lifetimes (averaged) respectively). Molecular docking and dynamic simulations reveal that genistein binds between the subunits of HbA, ~18?? away from the closest heme group of chain α1, emphasizing the fact that the drug does not interfere with oxygen binding site of HbA.展开更多
The focus of this article is based on the aqueous dispersed state properties of inorganic ZnO nanoparticles (average size ≤ 4 nm), their surface modification and bio-functionalization with folic acid at physiological...The focus of this article is based on the aqueous dispersed state properties of inorganic ZnO nanoparticles (average size ≤ 4 nm), their surface modification and bio-functionalization with folic acid at physiological pH ~ 7.5, suitable for bio-imaging and targeted therapeutic application. While TEM studies of the ZnO nano-crystallites have been performed to estimate their size and morphology in dry state, the band gap properties of the freshly prepared samples, the hydrodynamic size in aqueous solution phase and the wide fluorescence range in visible region have been investigated to establish the fact that the sol is particularly suitable for bio-medical purpose in the aqueous dispersed state.展开更多
Chromomycin A3 (CHR, pKa = 7.0), an aureolic acid group of antitumor antibiotic, undergoes self-association in aqueous solution in neutral and anionic forms. Self-association processes of neutral and anionic CHR have ...Chromomycin A3 (CHR, pKa = 7.0), an aureolic acid group of antitumor antibiotic, undergoes self-association in aqueous solution in neutral and anionic forms. Self-association processes of neutral and anionic CHR have been studied in pH 5.0 and pH 9.0, respectively using different spectroscopic methods such as absorbance, fluorescence, CD, NMR and isothermal titration calorimetry (ITC). Results from these studies reveal that at low concentration (2 + CHR (CHR)3 and (CHR)3 + CHR (CHR)4. Analysis of NMR spectra of 100 μM and 1 mM CHR indicates that the self-association of CHR (neutral and anionic form) is most likely to happen via hydrophobic interaction involving the sugar moieties and surrounding water molecules. Calorimetric studies indicate that self-association of both anionic and neutral CHR is entropy driven. These observations imply that sugar substituents play a major role in their state of aggregation after biosynthesis from a gene cluster. The self-association features of the antibiotic have been compared with those of Mithramycin, an antibiotic of the same group.展开更多
The cathode of biofuel cell reduces molecular oxygen to water using four electrons, an enzyme of multicopper oxidase family, laccase, is contained, though its electron transfer efficiency from the electrode resulted i...The cathode of biofuel cell reduces molecular oxygen to water using four electrons, an enzyme of multicopper oxidase family, laccase, is contained, though its electron transfer efficiency from the electrode resulted in rate determining process. To improve this electron, transfer via mediators, we have investigated several mediator metal complexes between the electrode and laccase, in particular hydrophobic pocket on the surface. We have discussed DFT computational results and selected experimental data of new Mn(III/II) Schiff base complexes having redox active (anthraquinone) ligands and photochromic (azobenzene) ligands about azobenzene moiety at the sole molecular level. Moreover, we carried out computational docking simulation of laccase and complexes considering trans-cis photoisomerization (electronic states) and Weigert effect (molecular orientation to fit better) of azobenzene moiety. Additionally, actual experimental data also presented to indicate the expected merits for mediators.展开更多
Background The response of superheated emulsion detector with different halocarbons as active liquid to poly-energetic and mono-energetic neutrons has been carried out by different workers.The C_(2)H_(2)F_(4)detectors...Background The response of superheated emulsion detector with different halocarbons as active liquid to poly-energetic and mono-energetic neutrons has been carried out by different workers.The C_(2)H_(2)F_(4)detectors have not been explored much.This liquid has shown the potentiality of sensitivity to low-mass dark matter.The previous calibration of this liquid was carried out with the poly-energetic neutrons.Purpose In the present work,to better characterize the detector with neutrons,it is irradiated with quasi-mono-energetic neutrons and the results are compared with neutrons from 241Am-Be.To run the detector for the dark matter search,it is required to calibrate it with neutrons,preferably with mono-energetic neutrons.But mono-energetic neutron is not available at all establishments;hence,it was calibrated with quasi-mono-energetic neutrons.Method The response of superheated emulsion consisting of the droplets of C_(2)H_(2)F_(4)has been studied using the quasi-mono-energetic neutrons.The superheated droplets have been fabricated in a visco-elastic gel matrix.The shock waves generated by the passage of the energetic particles are detected by the acoustic sensors coupled to the emulsion.The measurement has also been carried out for the blank target and beam-off conditions.Results and conclusion It is observed that the(Pvar)response of the emulsion in the low-frequency range is sharper for the quasi-mono-energetic neutrons from 7Li(p,n)reaction and wider for the poly-energetic neutrons from 241Am-Be.The fundamental frequency associated with bubble nucleation(FF values)is similar for the neutrons from 7Li-target and 241Am-Be source.The precise characterization of such detector is required for the application in neutron measurement as well as for the dark matter search experiment apart from the basic understanding of the radiation-induced bubble nucleation.展开更多
The excitation function of the 58Ni(n,p)58Co reaction was measured using the well-established neutron activation technique andγ-ray spectroscopy.Neutrons in the energy range of 1.7 to 2.7 MeV were generated using the...The excitation function of the 58Ni(n,p)58Co reaction was measured using the well-established neutron activation technique andγ-ray spectroscopy.Neutrons in the energy range of 1.7 to 2.7 MeV were generated using the 7Li(p,n)reaction.The neutron flux was measured using the standard 115In(n,n’)115mIn monitor reaction.The results of the neutron spectrum averaged cross-section of 58Ni(n,p)58Co reactions were compared with existing cross-section data available in the EXFOR data library as well as with various evaluated data libraries such as ENDF/B-VIII.0,JEFF-3.3,JENDL-4.0,and CENDL-3.2.Theoretical calculations were performed using the nuclear reaction code TALYS.Various nuclear level density(NLD)models were tested,and their results were compared with the present findings.Realistic NLDs were also obtained through the spectral distribution method(SDM).The cross-section results,along with the absolute errors,were obtained by investigating the uncertainty propagation and using the covariance technique.Corrections forγ-ray true coincidence summing,low-energy background neutrons,andγ-ray self attenuation were performed.The experimental cross-section obtained in the present study is consistent with previously published experimental data,evaluated libraries,and theoretical calculations carried out using the TALYS code.展开更多
A serious problem in secondary ion mass spectrometry (SI MS ) analysis is its “matrix effect” that hinders the quantification of a certain species in a sample and consequently, appropriate corrective measures are ta...A serious problem in secondary ion mass spectrometry (SI MS ) analysis is its “matrix effect” that hinders the quantification of a certain species in a sample and consequently, appropriate corrective measures are taken to calibrate the secondary ion currents into respective concentrations for accu rate compositional analysis. Use of “calibration standards” is necessary for t his purpose. Detection of molecular MCs_n+ ions (M-element to be analyz ed , n=1, 2, 3,….) under Cs+ ion bombardment is a possible mean to minimiz e such matrix effect, enabling one to quantify without the need of calibration sta ndards. Our recent studies on MCs_n+ molecular ions aim towards the understanding of their formation mechanisms, which are important to know their e ffects on SIMS quantification. In-depth quantitative analysis is a major strength of SIMS for which ‘depth resolution’ is of significant relevance. The optimal choice of the impact pa rameters during SIMS analyses can play an effective role in obtaining data with ultra-high depth resolution. SIMS is possible at depth resolution in the nm or even sub-nm rang e, with quantifiable data obtained from the top monolayer onwards into the material. Wi th optimized experimental conditions, like extremely low beam current (down to ～10 nA), and low bombarding energy (below 1 keV), ultra-high depth resolution SIMS has e nabled interfacial composition analysis of ultra-thin films, quantum wells, heterostru ctures, etc. and complex low-dimensional structures with high precision and re peatability.展开更多
Biological sequence alignment is one of the most important problems in computational biology. The objective of the alignment process is to maximize the alignment score between two given sequences of varying or equal l...Biological sequence alignment is one of the most important problems in computational biology. The objective of the alignment process is to maximize the alignment score between two given sequences of varying or equal length. The alignment score of two sequences is calculated based on matches, mismatches and gaps in the alignment. We have proposed a new genetic approach for finding optimized match between two DNA or protein sequences. The process is compared with two well known relevant sequence alignment techniques.展开更多
The purpose of thepresent study is to determine whether a long range correlation is present in BZ （Belousov-Zhabotinskii） reaction and how this correlation varies with the change in concentration of the solution. To...The purpose of thepresent study is to determine whether a long range correlation is present in BZ （Belousov-Zhabotinskii） reaction and how this correlation varies with the change in concentration of the solution. To explore the dynamics of the system with change in concentration, phase space plot and power spectrum are studied. Hurst exponent is estimated using log log plot and R/S technique. We discuss the results which uncover how the system changes from an excitable steady stateto a limit cycle,展开更多
Amyloid precursor protein intracellular domain （AICD） is one of the potential candidates in deciphering the complexity of Alzheimer＇s disease. It plays important roles in determining cell fate and neurodegeneration...Amyloid precursor protein intracellular domain （AICD） is one of the potential candidates in deciphering the complexity of Alzheimer＇s disease. It plays important roles in determining cell fate and neurodegeneration through its interactions with several adaptors. The pres- ence or absence of phosphorylation at specific sites determines the choice of partners. In this study, we identified 20 novel AICD- interacting proteins by in vitro pull down experiments followed by 2D gel electrophoresis and MALDI-MS analysis. The identified proteins can be grouped into different functional classes including molecular chaperones, structural proteins, signaling and transport molecules, adaptors, motor proteins and apoptosis determinants. Interactions of nine proteins were further validated either by colocal- ization using confocal imaging or by co-immunoprecipitation followed by immunoblotting. The cellular functions of most of the proteins can be correlated with AD. Hence, illustration of their interactions with AICD may shed some light on the disease pathophysiology.展开更多
Beta catenin has been well documented in previous studies to be involved in non small cell lung cancer(NSCLC).Beta catenin abundance and transcriptional activity are significantly regulated by several factors.Though i...Beta catenin has been well documented in previous studies to be involved in non small cell lung cancer(NSCLC).Beta catenin abundance and transcriptional activity are significantly regulated by several factors.Though it is well known that Akt and Gsk3 beta are respective positive and negative regulators of beta catenin,however,no single study has so far documented how the expression and activity of both positive as well as negative regulators play favorable role on beta catenin expression and activity in NSCLC.In this study,we compared expression and activity of beta catenin and its regulators in normal lung cell WI38 and NSCLC cell A549 by western blot,qRT-PCR and luciferase assay.We observed that beta catenin positive regulators(Akt and Hsp90)and negative regulators(Gsk3 beta and microRNA-214)have differential expression and/or activity in NSCLC cell A549.However the differentially altered statuses of both the positive and negative regulators rendered cumulative positive effect on beta catenin expression and activity in A549.Our study thus suggests that chemotherapeutic modulations of regulating factors are crucial when abrogation and/or inhibition of key oncogenic proteins are necessary for cancer chemotherapy.展开更多
Objective:The purpose of this work is the clinical commissioning of a recently developed in-vivo range verification system for the head treatment of pediatric medulloblastoma patients.Inaccurate beam range for such tr...Objective:The purpose of this work is the clinical commissioning of a recently developed in-vivo range verification system for the head treatment of pediatric medulloblastoma patients.Inaccurate beam range for such treatment could lead to either inadequate dose coverage of the target volume or excessive dose to the head skin resulting permanent alopecia.Methods:The in-vivo range verification system is designed to perform pre-treatment range verification and adjustment.An array of Si-diode detectors is to be placed on the patient immobilization mask in the exit direction of a whole-brain field;signal is analyzed,and the extracted water equivalent path length(WEPL)is compared to the expected one,revealing if a range correction is needed.The method was tested in solid water and anthropomorphic head phantom,with validation based on independent WEPL measurements.The measured WEPL were compared to those computed by the treatment planning system(TPS).Results:The accuracy for the WEPL measurements by the diode system in both solid water and anthropomorphic head phantom were on average within a millimeter from more accurate measurement by the dose-extinction technique,with the error range for the two phantoms as(0–1 mm)and(0–1.3 mm),respectively.When compared to the WEPL calculated by the treatment planning system,the measured values were on average within 1%(range 0–3%)of the beam range.The accuracy of dose measurements by the diodes in the fall-off part of the depth dose profile was validated against the reference Markus chamber.No need for further correction(due to different beam parameters and detector dose ageing effects)was found.Conclusions:The range verification workflow was successfully tested in the anthropomorphic head phantom.The performance of the in-vivo range verification system and related workflow meet the clinical requirements in terms of the needed WEPL accuracy for pretreatment range verification.展开更多
基金Supported by the Indian Council of Medical Research(ICMR)intramural projectDas C acknowledges the financial support from Biomolecular Assembly,Recognition and Dynamics (BARD) project(Grant 12-R&D-SIN-5.04-0103)from Department of Atomic Energy(DAE),Government of India and Ramalingaswami Fellowship,Department of Biotechnology,Government of India
文摘AIM Toll like receptors plays a significant anti-viral role in different infections. The aim of this study was to look into the role of toll like receptor 4(TLR4) in hepatitis B virus(HBV) infection.METHODS Real time PCR was used to analyze the transcription of TLR4 signaling molecules, cell cycle regulators and HBV DNA viral load after triggering the Hep G2.2.15 cells with TLR4 specific ligand. Nuclear factor(NF)-κB translocation on TLR4 activation was analyzed using microscopic techniques. Protein and cell cycle analysis was done using Western Blot and FACS respectively.RESULTS The present study shows that TLR4 activation represses HBV infection. As a result of HBV suppression, there are several changes in host factors which include partial release in G1/S cell cycle arrest and changes in host epigenetic marks. Finally, it was observed that anti-viral action of TLR4 takes place through the NF-κB pathway.CONCLUSION The study shows that TLR4 activation in HBV infection brings about changes in hepatocyte microenvironment and can be used for developing a promising therapeutic target in future.
文摘Medicinal plants, vegetables and fruits are the sources of huge number of bioactive lead/scaffolds with therapeutic and nutraceutical importance. Bioautography is a means of target-directed isolation of active molecules on chromatogram. Organic solvents employed in chromatographic separation process can be completely removed before biological detection because these solvents cause inactivation of enzymes and/or death of living organisms. They offer a rapid and easy identification of bioactive lead/scaffolds in complex matrices of plant extracts. Bioautography is a technique to isolate hit（s）/lead（s） by employing a suitable chromatographic process followed by a biological detection system. This review critically describes the methodologies to identify antimicrobial, antioxidant, enzyme inhibitor lead/scaffolds by employing bioautography. A significant number of examples have been incorporated to authenticate the methodologies.
文摘Very small nickel oxide nanoparticles were prepared by a sol-gel procedure using nickel nitrate hexahydrate and ammonium hydroxide as precursors. The particles are in the range of 5 nm-11 rim. The x-ray diffraction （XRD） crystallography and high resolution transmission electron microscopy （HRTEM） were employed to characterize the samples. They were found to be polycrystalline in nature and fcc （NaCl-type） in structure, with the lattice parameter varying with annealing temperature. HRTEM pictures show that the as-prepared samples are hexagonal in shape. Positron annihilation spectroscopy was used to investigate the Doppler-broadened spectra of the samples. The S and W parameters revealed that the chemical surroundings and momentum distribution of the vacancy clusters vary with crystallite size.
基金Project supported by the University Grants Commission(UGC),New Delhi,India,for the departmental CAS scheme(No.F.530/5/CAS/2011(SAP-Ⅰ))the Department of Science and Technology(DST),Govt.of India under FIST(Fund for Improvement in Science&Technology)Program(Grant No.SR/FST/PS-Ⅱ-001/2011)。
文摘Nanocrystalline samples of highly pure lead oxide were prepared by the sol-gel route of synthesis.X-ray diffraction and transmission electron microscopic techniques confirmed the nanocrystallinity of the samples,and the average sizes of the crystallites were found within 20 nm to 35 nm.The nanocrystallites exhibited specific anomalous properties,among which a prominent one is the increased lattice parameters and unit cell volumes.The optical band gaps also increased when the nanocrystallites became smaller in size.The latter aspect is attributable to the onset of quantum confinement effects,as seen in a few other metal oxide nanoparticles.Positron annihilation was employed to study the vacancy type defects,which were abundant in the samples and played crucial roles in modulating their properties.The defect concentrations were significantly larger in the samples of smaller crystallite sizes.The results suggested the feasibility of tailoring the properties of lead oxide nanocrystallites for technological applications,such as using lead oxide nanoparticles in batteries for better performance in discharge rate and resistance.It also provided the physical insight into the structural build-up process when crystallites were formed with a finite number of atoms,whose distributions were governed by the site stabilization energy.
文摘Steady state and time resolved fluorescence spectroscopy, combined with molecular dynamics simulation, have been used to explore the interactions of a therapeutically important bioflavonoid, genistein, with normal human hemoglobin (HbA). Binding constants estimated from the fluorescence studies were K = (3.5 ± 0.32) ×104M-1 for genistein. Specific interactions with HbA were confirmed from flavonoid-induced fluorescence quenching of the tryptophan in the protein HbA. The mechanism of this quenching involves both static and dynamic components as indicated by: (a) increase in the values of Stern-Volmer quenching constants with temperatures, (b) / is slightly > 1 (where and are the unquenched and quenched tryptophan fluorescence lifetimes (averaged) respectively). Molecular docking and dynamic simulations reveal that genistein binds between the subunits of HbA, ~18?? away from the closest heme group of chain α1, emphasizing the fact that the drug does not interfere with oxygen binding site of HbA.
文摘The focus of this article is based on the aqueous dispersed state properties of inorganic ZnO nanoparticles (average size ≤ 4 nm), their surface modification and bio-functionalization with folic acid at physiological pH ~ 7.5, suitable for bio-imaging and targeted therapeutic application. While TEM studies of the ZnO nano-crystallites have been performed to estimate their size and morphology in dry state, the band gap properties of the freshly prepared samples, the hydrodynamic size in aqueous solution phase and the wide fluorescence range in visible region have been investigated to establish the fact that the sol is particularly suitable for bio-medical purpose in the aqueous dispersed state.
文摘Chromomycin A3 (CHR, pKa = 7.0), an aureolic acid group of antitumor antibiotic, undergoes self-association in aqueous solution in neutral and anionic forms. Self-association processes of neutral and anionic CHR have been studied in pH 5.0 and pH 9.0, respectively using different spectroscopic methods such as absorbance, fluorescence, CD, NMR and isothermal titration calorimetry (ITC). Results from these studies reveal that at low concentration (2 + CHR (CHR)3 and (CHR)3 + CHR (CHR)4. Analysis of NMR spectra of 100 μM and 1 mM CHR indicates that the self-association of CHR (neutral and anionic form) is most likely to happen via hydrophobic interaction involving the sugar moieties and surrounding water molecules. Calorimetric studies indicate that self-association of both anionic and neutral CHR is entropy driven. These observations imply that sugar substituents play a major role in their state of aggregation after biosynthesis from a gene cluster. The self-association features of the antibiotic have been compared with those of Mithramycin, an antibiotic of the same group.
文摘The cathode of biofuel cell reduces molecular oxygen to water using four electrons, an enzyme of multicopper oxidase family, laccase, is contained, though its electron transfer efficiency from the electrode resulted in rate determining process. To improve this electron, transfer via mediators, we have investigated several mediator metal complexes between the electrode and laccase, in particular hydrophobic pocket on the surface. We have discussed DFT computational results and selected experimental data of new Mn(III/II) Schiff base complexes having redox active (anthraquinone) ligands and photochromic (azobenzene) ligands about azobenzene moiety at the sole molecular level. Moreover, we carried out computational docking simulation of laccase and complexes considering trans-cis photoisomerization (electronic states) and Weigert effect (molecular orientation to fit better) of azobenzene moiety. Additionally, actual experimental data also presented to indicate the expected merits for mediators.
文摘Background The response of superheated emulsion detector with different halocarbons as active liquid to poly-energetic and mono-energetic neutrons has been carried out by different workers.The C_(2)H_(2)F_(4)detectors have not been explored much.This liquid has shown the potentiality of sensitivity to low-mass dark matter.The previous calibration of this liquid was carried out with the poly-energetic neutrons.Purpose In the present work,to better characterize the detector with neutrons,it is irradiated with quasi-mono-energetic neutrons and the results are compared with neutrons from 241Am-Be.To run the detector for the dark matter search,it is required to calibrate it with neutrons,preferably with mono-energetic neutrons.But mono-energetic neutron is not available at all establishments;hence,it was calibrated with quasi-mono-energetic neutrons.Method The response of superheated emulsion consisting of the droplets of C_(2)H_(2)F_(4)has been studied using the quasi-mono-energetic neutrons.The superheated droplets have been fabricated in a visco-elastic gel matrix.The shock waves generated by the passage of the energetic particles are detected by the acoustic sensors coupled to the emulsion.The measurement has also been carried out for the blank target and beam-off conditions.Results and conclusion It is observed that the(Pvar)response of the emulsion in the low-frequency range is sharper for the quasi-mono-energetic neutrons from 7Li(p,n)reaction and wider for the poly-energetic neutrons from 241Am-Be.The fundamental frequency associated with bubble nucleation(FF values)is similar for the neutrons from 7Li-target and 241Am-Be source.The precise characterization of such detector is required for the application in neutron measurement as well as for the dark matter search experiment apart from the basic understanding of the radiation-induced bubble nucleation.
基金One of the authors(A.H.)sincerely acknowledges the Department of Science and Technology(DST),Government of Indiafor the INSPIRE Fellowship award(No.DST/INSPIRE Fellowship/2019/IF190924)+1 种基金partial support from the SERBwith grants No.SIR/2022/000566 and CRG/2021/000101,respectively。
文摘The excitation function of the 58Ni(n,p)58Co reaction was measured using the well-established neutron activation technique andγ-ray spectroscopy.Neutrons in the energy range of 1.7 to 2.7 MeV were generated using the 7Li(p,n)reaction.The neutron flux was measured using the standard 115In(n,n’)115mIn monitor reaction.The results of the neutron spectrum averaged cross-section of 58Ni(n,p)58Co reactions were compared with existing cross-section data available in the EXFOR data library as well as with various evaluated data libraries such as ENDF/B-VIII.0,JEFF-3.3,JENDL-4.0,and CENDL-3.2.Theoretical calculations were performed using the nuclear reaction code TALYS.Various nuclear level density(NLD)models were tested,and their results were compared with the present findings.Realistic NLDs were also obtained through the spectral distribution method(SDM).The cross-section results,along with the absolute errors,were obtained by investigating the uncertainty propagation and using the covariance technique.Corrections forγ-ray true coincidence summing,low-energy background neutrons,andγ-ray self attenuation were performed.The experimental cross-section obtained in the present study is consistent with previously published experimental data,evaluated libraries,and theoretical calculations carried out using the TALYS code.
文摘A serious problem in secondary ion mass spectrometry (SI MS ) analysis is its “matrix effect” that hinders the quantification of a certain species in a sample and consequently, appropriate corrective measures are taken to calibrate the secondary ion currents into respective concentrations for accu rate compositional analysis. Use of “calibration standards” is necessary for t his purpose. Detection of molecular MCs_n+ ions (M-element to be analyz ed , n=1, 2, 3,….) under Cs+ ion bombardment is a possible mean to minimiz e such matrix effect, enabling one to quantify without the need of calibration sta ndards. Our recent studies on MCs_n+ molecular ions aim towards the understanding of their formation mechanisms, which are important to know their e ffects on SIMS quantification. In-depth quantitative analysis is a major strength of SIMS for which ‘depth resolution’ is of significant relevance. The optimal choice of the impact pa rameters during SIMS analyses can play an effective role in obtaining data with ultra-high depth resolution. SIMS is possible at depth resolution in the nm or even sub-nm rang e, with quantifiable data obtained from the top monolayer onwards into the material. Wi th optimized experimental conditions, like extremely low beam current (down to ～10 nA), and low bombarding energy (below 1 keV), ultra-high depth resolution SIMS has e nabled interfacial composition analysis of ultra-thin films, quantum wells, heterostru ctures, etc. and complex low-dimensional structures with high precision and re peatability.
文摘Biological sequence alignment is one of the most important problems in computational biology. The objective of the alignment process is to maximize the alignment score between two given sequences of varying or equal length. The alignment score of two sequences is calculated based on matches, mismatches and gaps in the alignment. We have proposed a new genetic approach for finding optimized match between two DNA or protein sequences. The process is compared with two well known relevant sequence alignment techniques.
文摘The purpose of thepresent study is to determine whether a long range correlation is present in BZ （Belousov-Zhabotinskii） reaction and how this correlation varies with the change in concentration of the solution. To explore the dynamics of the system with change in concentration, phase space plot and power spectrum are studied. Hurst exponent is estimated using log log plot and R/S technique. We discuss the results which uncover how the system changes from an excitable steady stateto a limit cycle,
基金supported by the Structural Proteomics and Genomics of Human Genetic Disorders Project of Department of Atomic Energy
文摘Amyloid precursor protein intracellular domain （AICD） is one of the potential candidates in deciphering the complexity of Alzheimer＇s disease. It plays important roles in determining cell fate and neurodegeneration through its interactions with several adaptors. The pres- ence or absence of phosphorylation at specific sites determines the choice of partners. In this study, we identified 20 novel AICD- interacting proteins by in vitro pull down experiments followed by 2D gel electrophoresis and MALDI-MS analysis. The identified proteins can be grouped into different functional classes including molecular chaperones, structural proteins, signaling and transport molecules, adaptors, motor proteins and apoptosis determinants. Interactions of nine proteins were further validated either by colocal- ization using confocal imaging or by co-immunoprecipitation followed by immunoblotting. The cellular functions of most of the proteins can be correlated with AD. Hence, illustration of their interactions with AICD may shed some light on the disease pathophysiology.
基金This work was supported by DAE,Government of India.We thank Prof.Nitai Pada Bhattacharyya,Former Professor,Saha Institute of Nuclear Physics,Kolkata-700064 for providing the empty U61 and miR-214-U61 plasmids and primers of U6 snRNA and miR-214.
文摘Beta catenin has been well documented in previous studies to be involved in non small cell lung cancer(NSCLC).Beta catenin abundance and transcriptional activity are significantly regulated by several factors.Though it is well known that Akt and Gsk3 beta are respective positive and negative regulators of beta catenin,however,no single study has so far documented how the expression and activity of both positive as well as negative regulators play favorable role on beta catenin expression and activity in NSCLC.In this study,we compared expression and activity of beta catenin and its regulators in normal lung cell WI38 and NSCLC cell A549 by western blot,qRT-PCR and luciferase assay.We observed that beta catenin positive regulators(Akt and Hsp90)and negative regulators(Gsk3 beta and microRNA-214)have differential expression and/or activity in NSCLC cell A549.However the differentially altered statuses of both the positive and negative regulators rendered cumulative positive effect on beta catenin expression and activity in A549.Our study thus suggests that chemotherapeutic modulations of regulating factors are crucial when abrogation and/or inhibition of key oncogenic proteins are necessary for cancer chemotherapy.
文摘Objective:The purpose of this work is the clinical commissioning of a recently developed in-vivo range verification system for the head treatment of pediatric medulloblastoma patients.Inaccurate beam range for such treatment could lead to either inadequate dose coverage of the target volume or excessive dose to the head skin resulting permanent alopecia.Methods:The in-vivo range verification system is designed to perform pre-treatment range verification and adjustment.An array of Si-diode detectors is to be placed on the patient immobilization mask in the exit direction of a whole-brain field;signal is analyzed,and the extracted water equivalent path length(WEPL)is compared to the expected one,revealing if a range correction is needed.The method was tested in solid water and anthropomorphic head phantom,with validation based on independent WEPL measurements.The measured WEPL were compared to those computed by the treatment planning system(TPS).Results:The accuracy for the WEPL measurements by the diode system in both solid water and anthropomorphic head phantom were on average within a millimeter from more accurate measurement by the dose-extinction technique,with the error range for the two phantoms as(0–1 mm)and(0–1.3 mm),respectively.When compared to the WEPL calculated by the treatment planning system,the measured values were on average within 1%(range 0–3%)of the beam range.The accuracy of dose measurements by the diodes in the fall-off part of the depth dose profile was validated against the reference Markus chamber.No need for further correction(due to different beam parameters and detector dose ageing effects)was found.Conclusions:The range verification workflow was successfully tested in the anthropomorphic head phantom.The performance of the in-vivo range verification system and related workflow meet the clinical requirements in terms of the needed WEPL accuracy for pretreatment range verification.
