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1.
J Chem Eng Data ; 69(2): 307-319, 2024 Feb 08.
Artículo en Inglés | MEDLINE | ID: mdl-38352074

RESUMEN

Data for several key thermodynamic and transport properties needed for technologies using hydrogen (H2), such as underground H2 storage and H2O electrolysis are scarce or completely missing. Force field-based Molecular Dynamics (MD) and Continuous Fractional Component Monte Carlo (CFCMC) simulations are carried out in this work to cover this gap. Extensive new data sets are provided for (a) interfacial tensions of H2 gas in contact with aqueous NaCl solutions for temperatures of (298 to 523) K, pressures of (1 to 600) bar, and molalities of (0 to 6) mol NaCl/kg H2O, (b) self-diffusivities of infinitely diluted H2 in aqueous NaCl solutions for temperatures of (298 to 723) K, pressures of (1 to 1000) bar, and molalities of (0 to 6) mol NaCl/kg H2O, and (c) solubilities of H2 in aqueous NaCl solutions for temperatures of (298 to 363) K, pressures of (1 to 1000) bar, and molalities of (0 to 6) mol NaCl/kg H2O. The force fields used are the TIP4P/2005 for H2O, the Madrid-2019 and the Madrid-Transport for NaCl, and the Vrabec and Marx for H2. Excellent agreement between the simulation results and available experimental data is found with average deviations lower than 10%.

2.
Plant Dis ; 2022 Oct 21.
Artículo en Inglés | MEDLINE | ID: mdl-36269591

RESUMEN

Fox nut also known as Gorgon nut, Makhana (Euryale ferox Salisb.) is a high value aquatic crop belonging to the family Nymphaeaceae. In India, it is generally grown in flood prone areas of North Bihar, lower Assam, parts of West Bengal, Odisha, Manipur and Tripura (Jana et al., 2018). India contributes nearly 70-80% of the global fox nut production. During September 2021, a phytoplasma like symptom was noticed on fox nut leaves at Basudeopur Farm of Research Centre for Makhana, Darbhanga, Bihar, India (23° 9' N and 65° 53' E). The characteristic symptom was that some portion of leaf lamina deformed along the veins with wrinkled and raised overgrowth or hypertrophy. The veins were thickened and reddened in the infected leaf area. The infection occurs in petiole as well as in flower stalk. The disease incidence was found as high as 30% which caused severe yield loss which was calculated to be 40% in that particular field. Total of 20 sampled fox nut plants, 10 symptomatic and 10 asymptomatic ones, were collected and tested for the presence of phytoplasma. A nested PCR assay using the phytoplasma universal 16S rRNA primer pairs: P1/P7 followed by R16F2n/R16R2 (J. Jovic et al. 2011) amplified the expected ~1.2-kb 16S rDNA fragment in all 10 symptomatic samples. No amplification was detected from asymptomatic samples. One of the ten 1.2-kb nested 16S rDNA PCR products was gel purified, cloned into the pGEM-T-easy plasmid vector (Promega, Madison, WI), and sequenced and was deposited in NCBI under the Accession no.OL873590. BLAST analysis showed that the sequence of the PCR 16S rDNA product was 100% identical to several GenBank sequences of Ca. P. solani (16SrXII Stolbur group) viz. KF907506. Furthermore, analysis by iPhyClassifier software showed that the virtual restriction fragment length polymorphism (RFLP) pattern of the sequenced PCR 16S rDNA product is identical (similarity coefficient 1.00) to the reference pattern of the 16SrXII-A subgroup. Identification of 'Ca. P. solani' was conducted following the STOL11 stolbur-specific protocol (Radonjic et al. 2009). Sequencing of tuf gene (Elongation factor Tu) was performed by using tuf marker genes (Cvrkovic et al. 2014) from 10 symptomatic and 10 asymptomatic samples. Sequence of the amplified gene (896 bp) was deposited in GenBank under Accession number OM174272. The presence of 'Ca. P. solani' was detected in all symptomatic samples, while all control plants tested negative. The RFLP analysis of tuf gene nested PCR products using HpaII endonuclease (Fermentas) revealed uniform tuf-b type in all positive samples. Nucleotide blast analyses showed that the tuf gene was 100% identical to STOL11 strain of C. P. solani subgroup 16SrXII-A (Accession No JQ797670). For developing a suitable management strategy, identification of the vector is essential. Leaf hoppers visiting the infected plants as well as nearby crop fields will be tested for presence of the phytoplasma. To the best of our knowledge, this is the first report of Candidatus Phytoplasma solani' (16SrXII-A) infecting Fox nut (Euryale ferox Salisb.) in India. References Cvrkovic et al. 2014. Plant Pathol. 63:42. https://doi.org/10.1111/ppa.12080 Jana, B. R., et al. 2018. Int. J. Curr. Microbiol. App. Sci. 7(12): 578-587. https://doi.org/10.20546/ijcmas.2018.712.072 Jovic, J. et al. 2011. B. Insectol. 64:S83. ISI Radonjic, S. et al. 2009. J. Phytopathol. 157:682. https://doi.org/10.1111/j.1439- 0434.2009.01560.

3.
Genomics ; 113(3): 1037-1047, 2021 05.
Artículo en Inglés | MEDLINE | ID: mdl-33482327

RESUMEN

The 297 winter rice accessions of Assam, North East India were genotyped by sequencing (GBS). The 50,985 high-quality SNPs were filtered and assigned to 12 rice chromosomes. The population structure analysis revealed three major subgroups SG1, SG2, and SG3 consisting of 30, 8, and 143 accessions respectively. The remaining 116 accessions were grouped as admixture population. Phenotypic data were recorded on13 agronomical traits for genome-wide association studies (GWAS). The 60 significant marker-trait associations (MTAs) were identified for 11 agronomical traits, which explained 0 to 15% of phenotypic variance (PV). A QTL 'hot spot' was detected near the centromeric region on chromosome 6. The identified QTLs may be validated and utilized in 'genomics assisted breeding' for improvement of existing rice cultivars of Assam and North East India.


Asunto(s)
Estudio de Asociación del Genoma Completo , Oryza , Oryza/genética , Fenotipo , Fitomejoramiento , Polimorfismo de Nucleótido Simple , Sitios de Carácter Cuantitativo
4.
Opt Express ; 29(23): 38415-38428, 2021 Nov 08.
Artículo en Inglés | MEDLINE | ID: mdl-34808895

RESUMEN

Imaging interferometric microscopy (IIM) is an optical microscopy resolution enhancement technique involving combining multiple sub-images to increase resolution. Several image reconstruction challenges can degrade the image quality including the frequency, phase deviations between sub-images, and maintenance of a uniform frequency response across the entire space. This work proposes methods to address these issues. The methods are first compared in simulation using a Manhattan structure of 260-nm critical dimension with 2-µm-pitch calibration grating on the sides. The proposed correction methods are then applied to the experimental results and found to be effective in improving the image quality of IIM.

5.
J Postgrad Med ; 67(1): 12-17, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33565472

RESUMEN

BACKGROUND: Craving plays an important role in maintenance of alcohol dependence. Earlier studies have analyzed the role of ghrelin in craving and their results have been heterogenous. Acyl ghrelin is its more active form as it crosses the blood brain barrier. Hence we aimed to examine the relationship between plasma acyl ghrelin and craving in Indian patients having alcohol dependence syndrome. METHODS: The present study was a hospital-based prospective study. A total of 60 drug-naive patients of alcohol dependence and 30 healthy controls were included. After taking informed consent fasting blood samples were collected from them on day 1 and tested for plasma acyl ghrelin level. Fasting blood samples were repeated in all cases on day 14. During this time, we also assessed the patients' cravings by obsessive compulsive drinking scale, and alcohol craving questionnaire; and withdrawal by clinical institute withdrawal assessment for alcohol scale. These scales were repeated on day 14. Data analysis was done by SPSS version 25.0. RESULTS: Plasma concentrations of acyl ghrelin increased significantly during early abstinence in patients from day 1 to day 14 (P < 0.0001). Pearson correlation test revealed a trend of positive correlation between plasma concentration of acyl ghrelin on day 14 and severity of craving on day 1. CONCLUSION: Our results suggest the plasma concentration of acyl ghrelin may be a predictor of severity of alcohol craving during early abstinence. Anti-craving drugs acting on acyl ghrelin level in brain may open an innovative avenue for optimum treatment of alcohol dependence.


Asunto(s)
Consumo de Bebidas Alcohólicas/epidemiología , Alcoholismo/sangre , Ansia , Ghrelina/sangre , Adulto , Consumo de Bebidas Alcohólicas/sangre , Alcoholismo/epidemiología , Alcoholismo/psicología , Biomarcadores/sangre , Estudios de Casos y Controles , Femenino , Humanos , India/epidemiología , Masculino , Persona de Mediana Edad , Prevalencia , Estudios Prospectivos , Encuestas y Cuestionarios , Adulto Joven
6.
Encephale ; 47(3): 189-194, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33309007

RESUMEN

BACKGROUND: Internet is being used extensively throughout the world from last decade. In India internet service has entered into new generation called 4G. Medical students are particularly vulnerable group for problematic internet use on account of the time they spend online. This might have negative effects on their physical, psychological and social health. Hence they are more prone to internet addiction. AIMS: To compare use and effect of internet service among medical students before and after the availability of 4G service. STUDY DESIGN: Institution based cross sectional study. METHODS AND MATERIAL: Predesigned validated questionnaires were provided to the medical students in the year 2014. The questionnaire included demographics, pattern of internet use and Young's internet addiction test. Again in the year 2018 the similar procedure was carried out after introduction of 4G service. The data was collected and compared. Analysis was done using SPSS 25. STATISTICAL ANALYSIS: Descriptive statistics, Chi2 test and Mann-Whitney test was applied. RESULTS: Among 424 medical students 207 students were assessed in the year 2014 and 217 students in 2018.There was a significant change of pattern of use. Also significant increase in number of female users and severity of internet addiction in 2018. The ill effect of internet was on rise after availability of 4G service. CONCLUSIONS: The prevalence of internet addiction and its ill effect on behavior among medical students was higher after availability of 4G service in same college. So appropriate preventive and interventional strategies need to be developed in professional institutions.


Asunto(s)
Conducta Adictiva , Estudiantes de Medicina , Conducta Adictiva/epidemiología , Estudios Transversales , Femenino , Humanos , India/epidemiología , Internet , Uso de Internet
7.
Cytopathology ; 29(3): 288-293, 2018 06.
Artículo en Inglés | MEDLINE | ID: mdl-29575183

RESUMEN

INTRODUCTION: Cytology of giant cell tumour of tendon sheath (GCTTS) is often sufficient to diagnose this lesion and has been previously described in small series. The present study was undertaken to evaluate detailed cytomorphological features and differential diagnostic entities and pitfalls in the diagnosis. METHODS: All the cases of GCTTS reported on FNAC were retrieved from July 2007 to June 2017. The cases were reviewed for various cytomorphological features, which were correlated with follow-up histopathology wherever available. RESULTS: A total of 72 cases of GCTTS were retrieved, follow-up histopathology was available in 20 cases. The common sites of involvement were fingers and palm followed by wrists, elbow, knee, ankle and shoulder. The characteristic cytomorphology consisted of mononuclear cells, multinucleated giant cells and pigment laden macrophages in variable numbers. There were four discordant cases that were confirmed on histopathology as sarcoidosis, melanoma, fibrous histiocytoma and eumycetoma. CONCLUSIONS: GCTTS can be confused cytologically with giant cell rich lesions of bone and soft tissue and pigment containing lesions including melanoma. Ladybird cell is a characteristic feature seen in this lesion. Proper clinicoradiological correlation is essential before offering a diagnosis of GCTTS on cytology.


Asunto(s)
Tumor de Células Gigantes de las Vainas Tendinosas/patología , Tumores de Células Gigantes/patología , Células Gigantes/patología , Tendones/patología , Adolescente , Adulto , Anciano , Niño , Preescolar , Femenino , Humanos , Lactante , Masculino , Persona de Mediana Edad , Centros de Atención Terciaria , Adulto Joven
8.
Phys Rev Lett ; 119(13): 137401, 2017 Sep 29.
Artículo en Inglés | MEDLINE | ID: mdl-29341682

RESUMEN

Using time-resolved Kerr rotation, we measure the spin-valley dynamics of resident electrons and holes in single charge-tunable monolayers of the archetypal transition-metal dichalcogenide (TMD) semiconductor WSe_{2}. In the n-type regime, we observe long (∼130 ns) polarization relaxation of electrons that is sensitive to in-plane magnetic fields B_{y}, indicating spin relaxation. In marked contrast, extraordinarily long (∼2 µs) polarization relaxation of holes is revealed in the p-type regime, which is unaffected by B_{y}, directly confirming long-standing expectations of strong spin-valley locking of holes in the valence band of monolayer TMDs. Supported by continuous-wave Kerr spectroscopy and Hanle measurements, these studies provide a unified picture of carrier polarization dynamics in monolayer TMDs, which can guide design principles for future valleytronic devices.

9.
Lett Appl Microbiol ; 65(1): 2-10, 2017 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-28421612

RESUMEN

As virulence of many pathogenic bacteria is regulated by the phenomenon of quorum sensing (QS), the present study aimed to find the QS-inhibiting (QS-I) property (if any) in 61 Indian medicinal plants. The presence of QS-I compound in the leaf extract was evaluated by its ability to inhibit production of pigment in Chromobacterium violaceum MTCC 2656 (violacein) and Pseudomonas aeruginosa MTCC 2297 (pyocyanin) or swarming of P. aeruginosa MTCC 2297. Extracts of three plants, Astilbe rivularis, Fragaria nubicola and Osbeckia nepalensis, have shown a dose-dependent inhibition of violacein production with no negative effect on bacterial growth. Inhibition of pyocyanin pigment production and swarming motility in P. aeruginosa MTCC 2297 was also shown. Based on the results obtained by gas chromatography-mass spectroscopy (GC-MS) and thin-layer chromatography-direct bioautography (TLC-DB), it was concluded that triterpenes and flavonoid compounds found in the three plant extracts could have QS-I activity. SIGNIFICANCE AND IMPACT OF THE STUDY: A novel alternative prospect to prevent bacterial infections without inhibiting the growth is to apply chemicals that inhibit quorum sensing mechanism of the pathogens. Antiquorum property of 61 medicinal plants was evaluated by the ability of their leaf extract(s) to inhibit production of pigment (violacein in Chromobacterium violaceum MTCC 2656, pyocyanin in Pseudomonas aeruginosa MTCC 2297) or swarming in P. aeruginosa MTCC 2297. The most prospective plants (for the development of quorum sensing inhibitor), showing inhibition of violacein production without affecting bacterial growth, were Astilbe rivularis, Fragaria nubicola and Osbeckia nepalensis.


Asunto(s)
Chromobacterium/efectos de los fármacos , Flavonoides/farmacología , Indoles/metabolismo , Pseudomonas aeruginosa/efectos de los fármacos , Piocianina/biosíntesis , Percepción de Quorum/efectos de los fármacos , Triterpenos/farmacología , Antibacterianos/farmacología , Fragaria/química , Medicina Tradicional , Melastomataceae/química , Extractos Vegetales/farmacología , Hojas de la Planta/química , Plantas Medicinales/química , Estudios Prospectivos , Saxifragaceae/química
10.
Cytopathology ; 28(2): 140-148, 2017 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-27510614

RESUMEN

BACKGROUND: Exfoliated endometrial cells can be seen in cervical smears in association with a wide variety of conditions ranging from normal proliferative endometrium to endometrial malignancies. It is often difficult to differentiate between benign, atypical and malignant endometrial cells using cytomorphology alone. This study was conducted to evaluate if morphometric analysis of endometrial nuclei on liquid-based cervical samples could be of help in differentiating between these endometrial cells. MATERIALS AND METHODS: Three groups of cervical samples with histopathological correlation were selected: Group A: showing benign endometrial cells; Group B: showing atypical endometrial cells and Group C: showing malignant endometrial cells. There were 30 cases each in Group A and B and 39 cases in Group C. Image J, NIH, USA was used for selecting the endometrial nuclei and performing the morphometric measurements. MANOVA was used for statistical analysis. RESULTS: The mean nuclear area and nuclear perimeter were significantly different between the three groups of endometrial cells with a P-value <0.05. However, the mean standard deviation of the nuclear area (SDNA) was not significantly different between atypical and malignant endometrial cells (P = 0.765) and the mean nuclear diameter was not statistically different between benign and atypical cells (P = 0.112). Also, the difference in the mean integrated gray density amongst all three groups was not statistically significant (P = 0.397, 0.844, 0.732). CONCLUSION: We conclude that the morphometric parameters of the nuclear area and nuclear perimeter are helpful in differentiating between benign, atypical and malignant endometrial nuclei even in liquid-based cervical cytology samples.


Asunto(s)
Adenocarcinoma/patología , Hiperplasia Endometrial/patología , Neoplasias Endometriales/patología , Endometrio/patología , Adenocarcinoma/diagnóstico , Adulto , Anciano , Núcleo Celular/patología , Hiperplasia Endometrial/diagnóstico , Neoplasias Endometriales/diagnóstico , Femenino , Humanos , Persona de Mediana Edad , Prueba de Papanicolaou/métodos , Frotis Vaginal/métodos
12.
Phys Rev Lett ; 116(12): 127402, 2016 Mar 25.
Artículo en Inglés | MEDLINE | ID: mdl-27058100

RESUMEN

We systematically investigate the excitonic dephasing of three representative transition-metal dichalcogenides, namely, MoS_{2}, MoSe_{2}, and WSe_{2} atomic monolayer thick and bulk crystals, in order to gain a proper understanding of the factors that determine the optical coherence in these materials. Coherent nonlinear optical spectroscopy and temperature dependent absorption, combined with theoretical calculations of the phonon spectra, indicate electron-phonon interactions, to be the limiting factor. Surprisingly, the excitonic dephasing, differs only slightly between atomic monolayers and high quality bulk crystals, which indicates that material imperfections are not the limiting factor in atomically thin monolayer samples. The temperature dependence of the electronic band gap and the excitonic linewidth combined with "ab initio" calculations of the phonon energies and the phonon density of states reveal a strong interaction with the E' and E" phonon modes.

13.
Phys Rev Lett ; 116(15): 157401, 2016 04 15.
Artículo en Inglés | MEDLINE | ID: mdl-27127985

RESUMEN

In modulation doped quantum wells, the excitons are formed as a result of the interactions of the charged holes with the electrons at the Fermi edge in the conduction band, leading to the so-called "Mahan excitons." The binding energy of Mahan excitons is expected to be greatly reduced and any quantum coherence destroyed as a result of the screening and electron-electron interactions. Surprisingly, we observe strong quantum coherence between the heavy hole and light hole excitons. Such correlations are revealed by the dominating cross-diagonal peaks in both one-quantum and two-quantum two-dimensional Fourier transform spectra. Theoretical simulations based on the optical Bloch equations where many-body effects are included phenomenologically reproduce well the experimental spectra. Time-dependent density functional theory calculations provide insight into the underlying physics and attribute the observed strong quantum coherence to a significantly reduced screening length and collective excitations of the many-electron system.

14.
Cytopathology ; 27(6): 452-455, 2016 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-27019215

RESUMEN

BACKGROUND: Papanicolaou (Pap) staining is used with various modifications for the staining of cervical smears. It gives a good contrast with sharp nuclear features which aid in accurate interpretation. However, it utilises ethyl alcohol, which is expensive and difficult to purchase. We have attempted to devise a rapid Pap technique which uses acetic acid instead of ethyl alcohol, and yet provides good staining for correct diagnosis. METHODS: Liquid-based cytology samples were collected from 102 patients as a part of routine screening. Two smears were prepared from each sample, which were stained with conventional as well as rapid Pap. In the rapid Pap method, the smears were fixed in methanol and dehydration was performed before and after OG6 with 0.5% acetic acid. The final dehydration was performed with methanol. Smears from both techniques were compared by two independent observers for staining quality. RESULTS: With the rapid Pap stain, nuclear staining was comparable with that of conventional Pap (P < 0.05). Cytoplasmic staining was optimal in 69.6% of cases; however, the suboptimal staining in the rest of the smears did not pose any diagnostic problem. CONCLUSION: The rapid Pap technique is a cost-effective alternative to conventional Pap which also saves time and provides good staining quality without compromising the diagnostic interpretation.


Asunto(s)
Citodiagnóstico/métodos , Prueba de Papanicolaou/métodos , Neoplasias del Cuello Uterino/diagnóstico , Frotis Vaginal/métodos , Femenino , Humanos , Neoplasias del Cuello Uterino/patología
15.
Cytopathology ; 27(6): 418-426, 2016 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-27121698

RESUMEN

BACKGROUND: Pseudomyxoma peritonei (PMP) is a rare clinical syndrome characterised by distension of the peritoneum by jelly-like ascites. Cytological evaluation of peritoneal fluid is often an initial diagnostic test for possible ovarian and/or appendiceal primary tumours. AIMS AND OBJECTIVES: The present work was conducted to study the usefulness of peritoneal fluid cytomorphology in the early diagnosis of PMP and to evaluate the significance of the presence of epithelial cell (EC) clusters and their prognostic implications. MATERIALS AND METHODS: We evaluated the detailed cytological features of 21 cases of PMP retrospectively. Both conventional and liquid-based cytology smears of peritoneal fluid were reviewed, cytological features were compared with histological findings and cases were classified into disseminated peritoneal adenomucinosis (DPAM) and peritoneal mucinous carcinomatosis (PMCA). RESULTS: In our study, the common causes of PMP were primary gastrointestinal malignancies (appendix and colorectal, 57.14%), followed by primary ovarian mucinous neoplasms (28.57%) and synchronous ovarian and appendicular tumours (14.28%). Thick mucinous material was present in all cases (100%). ECs were present in 18 of 21 (85.17%) patients, with mild nuclear atypia in the majority of cases. Histiocytes, mesothelial cells and fibroblast-like, spindle-shaped cells with entrapped mucin were also noted in the background. The cases of PMCA showed greater numbers of EC clusters in cytology smears and these patients had recurrent episodes of PMP. CONCLUSION: On cytomorphology, high-grade tumours were more cellular and frequently showed EC clusters with moderate to severe atypia, prominent nucleoli and mitosis, and were more prone to PMCA.


Asunto(s)
Neoplasias del Apéndice/diagnóstico , Citodiagnóstico , Neoplasias Ováricas/diagnóstico , Neoplasias Peritoneales/diagnóstico , Seudomixoma Peritoneal/diagnóstico , Adenocarcinoma Mucinoso/diagnóstico , Adenocarcinoma Mucinoso/patología , Adulto , Anciano , Anciano de 80 o más Años , Neoplasias del Apéndice/patología , Líquido Ascítico/patología , Diagnóstico Diferencial , Células Epiteliales/patología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Neoplasias Ováricas/patología , Neoplasias Peritoneales/patología , Seudomixoma Peritoneal/patología
16.
Malays J Pathol ; 38(3): 321-325, 2016 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-28028304

RESUMEN

Most cases of Zollinger-Ellison syndrome (ZES) are described in adults. It is a rare disorder in childhood. Most cases present with abdominal pain due to peptic ulceration and chronic diarrhoea not responding to general measures. The symptom complex is initially confused with other more common diseases, which lead to a delay in diagnosis. We present a rare case of a-12-year boy who initially presented with abdominal pain, diarrhoea, vomiting and progressive weight loss for over a two-year period before he was finally diagnosed as a case of ZES with the primary tumour in the pancreatic head and with multiple metastasis in both the liver and lymph nodes.


Asunto(s)
Síndrome de Zollinger-Ellison/complicaciones , Síndrome de Zollinger-Ellison/diagnóstico , Dolor Abdominal/etiología , Niño , Enfermedad Crónica , Diarrea/etiología , Humanos , Masculino , Vómitos/etiología , Pérdida de Peso
17.
J Chem Phys ; 142(21): 212422, 2015 Jun 07.
Artículo en Inglés | MEDLINE | ID: mdl-26049442

RESUMEN

Nonlinear two-dimensional Fourier transform (2DFT) and linear absorption spectroscopy are used to study the electronic structure and optical properties of excitons in the layered semiconductor GaSe. At the 1s exciton resonance, two peaks are identified in the absorption spectra, which are assigned to splitting of the exciton ground state into the triplet and singlet states. 2DFT spectra acquired for co-linear polarization of the excitation pulses feature an additional peak originating from coherent energy transfer between the singlet and triplet. At cross-linear polarization of the excitation pulses, the 2DFT spectra expose a new peak likely originating from bound biexcitons. The polarization dependent 2DFT spectra are well reproduced by simulations using the optical Bloch equations for a four level system, where many-body effects are included phenomenologically. Although biexciton effects are thought to be strong in this material, only moderate contributions from bound biexciton creation can be observed. The biexciton binding energy of ∼2 meV was estimated from the separation of the peaks in the 2DFT spectra. Temperature dependent absorption and 2DFT measurements, combined with "ab initio" theoretical calculations of the phonon spectra, indicate strong interaction with the A1 (') phonon mode. Excitation density dependent 2DFT measurements reveal excitation induced dephasing and provide a lower limit for the homogeneous linewidth of the excitons in the present GaSe crystal.

18.
Br J Cancer ; 111(3): 486-96, 2014 Jul 29.
Artículo en Inglés | MEDLINE | ID: mdl-25003666

RESUMEN

BACKGROUND: Cancer stem cells (CSCs) contribute towards disease aggressiveness and drug resistance. Specific identification of CSC maintenance genes and targeting can improve the efficiency of currently available treatment modalities. Pancreatic differentiation 2 (PD2) has a major role in the self-renewal of mouse embryonic stem cells. In the present study, we investigated the role of PD2 in pancreatic CSCs. METHODS: Characterisation of CSCs and non-CSCs from mouse models, pancreatic cancer cells and human tissues by CSC and self-renewal marker analysis using confocal assay. Effect of PD2 knockdown in CSCs (after gemcitabine treatment) was studied by immunoblot and apoptosis assays. RESULTS: A subpopulation of cells displayed PD2 overexpression in mouse (Kras(G12D); Pdx1-Cre and Kras(G12D); Trp53(R172H/+); Pdx1-Cre) and human pancreatic tumours, which co-express CSC markers. Cancer stem cells exhibited elevated expression of PD2 and self-renewal markers, such as Oct3/4, Shh and ß-catenin. Gemcitabine treatment maintained the CSC population with simultaneous maintenance of PD2 and CSC marker expression. Knockdown of PD2 in CSCs resulted in reduced viability of cells and enhanced apoptosis along with abrogated expression of CD133 and MDR2. CONCLUSIONS: Our results suggest that PD2 is a novel CSC maintenance protein, loss of which renders the CSCs more susceptible to drug-induced cell death.


Asunto(s)
Carcinoma Ductal Pancreático/metabolismo , Proliferación Celular , Resistencia a Antineoplásicos , Células Madre Neoplásicas/metabolismo , Proteínas Nucleares/fisiología , Neoplasias Pancreáticas/metabolismo , Animales , Antimetabolitos Antineoplásicos/farmacología , Biomarcadores de Tumor/metabolismo , Carcinoma Ductal Pancreático/patología , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Desoxicitidina/análogos & derivados , Desoxicitidina/farmacología , Técnicas de Silenciamiento del Gen , Humanos , Ratones , Ratones Transgénicos , Células Madre Neoplásicas/efectos de los fármacos , Neoplasias Pancreáticas/patología , Células de Población Lateral/efectos de los fármacos , Células de Población Lateral/metabolismo , Factores de Transcripción , Gemcitabina
20.
J Chem Phys ; 141(13): 134505, 2014 Oct 07.
Artículo en Inglés | MEDLINE | ID: mdl-25296819

RESUMEN

The dephasing of the Fermi edge singularity excitations in two modulation doped single quantum wells of 12 nm and 18 nm thickness and in-well carrier concentration of ∼4 × 10(11) cm(-2) was carefully measured using spectrally resolved four-wave mixing (FWM) and two-dimensional Fourier transform (2DFT) spectroscopy. Although the absorption at the Fermi edge is broad at this doping level, the spectrally resolved FWM shows narrow resonances. Two peaks are observed separated by the heavy hole/light hole energy splitting. Temperature dependent "rephasing" (S1) 2DFT spectra show a rapid linear increase of the homogeneous linewidth with temperature. The dephasing rate increases faster with temperature in the narrower 12 nm quantum well, likely due to an increased carrier-phonon scattering rate. The S1 2DFT spectra were measured using co-linear, cross-linear, and co-circular polarizations. Distinct 2DFT lineshapes were observed for co-linear and cross-linear polarizations, suggesting the existence of polarization dependent contributions. The "two-quantum coherence" (S3) 2DFT spectra for the 12 nm quantum well show a single peak for both co-linear and co-circular polarizations.

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