831 research outputs found
Nanoparticle size characterization by laser light scattering
Spherical semiconductor nanoparticles (ZnS) were specially fabricated by
an inexpensive chemical route. The scattering profile of the nanoparticles was
investigated by laser light scattering technique. A beam of polarized light from a
diode laser (.0˜ 630 nm) was allowed to fall on the nanospheres embedded in flexible
host matrix Polyvinyl Alcohol (PVA). The light scattered from the samples were
detected by means of analyzer mounted photodiode array from 10° to 170° in steps of
1°. Signals from the detectors were interfaced with a high resolution data
acquisition system and the whole experiment was carried out in differential mode.
Size of the nanoparticles was obtained by using Mie theory and verified by T-matrix
approach. The results obtained agree with the XRD and TEM results.Nanoparticle size characterization by laser light scattering
A Gogoi*, G A Ahmed and A Choudhury
Optoelectronics and Photonics Laboratory, Department of Physics,
Tezpur University, Tezpur-784 028, Assam, India
E-mail : [email protected] and Photonics Laboratory, Department of Physics,
Tezpur University, Tezpur-784 028, Assam, Indi
Can social accountability initiatives improve maternal health in India?
Susan A. Papp, Aparajita Gogoi, and Catherine Campbell present a case study of efforts to improve service accountability in Odisha, India, focusing on the role of local women, intermediary groups, health providers and elected politicians
Steady State Photo Carrier Grating Technique for Measurement of Charge Carrier Diffusion Length
On spectra of Hermitian Randic matrix of second kind
We propose the Hermitian Randi\'c matrix , where
and if
is an unoriented edge, if , if , and 0
otherwise. This appears to be more natural because of
and . In this paper, we investigate
some features of this novel Hermitian matrix and study a few properties like
positiveness, bipartiteness, edge-interlacing etc. We also compute the
characteristic polynomial for this new matrix and obtain some upper and lower
bounds for the eigenvalues and the energy of this matrix
Unravelling multi-temperature dust populations in the dwarf galaxy Holmberg II
Holmberg II - a dwarf galaxy in the nearby M81 group - is a very informative
source of distribution of gas and dust in the interstellar discs.
High-resolution observations in the infrared (IR) allows us to distinguish
isolated star-forming regions, photodissociation (PDR) and HII regions,
remnants of supernovae (SNe) explosions and, as such, can provide information
about more relevant physical processes. In this paper we analyse dust emission
in the wavelength range 4.5 to 160 micron using the data from IR space
observatories at 27 different locations across the galaxy. We observe that the
derived spectra can be represented by multiple dust populations with different
temperatures, which are found to be independent of their locations in the
galaxy. By comparing the dust temperatures with the far ultraviolet (FUV)
intensities observed by the UVIT instrument onboard AstroSat, we find that for
locations showing a 100 micron peak, the temperature of cold (20 to 30 K) dust
grains show a dependence on the FUV intensities, while such dependence is not
observed for the other locations. We believe that the approach described here
can be a good tool in revealing different dust populations in other nearby
galaxies with available high spatial resolution data.Comment: 7 pages, 4 figures, submitted to Letters to MNRA
From confined spinons to emergent fermions: Observation of elementary magnetic excitations in a transverse-field Ising chain
We report on spectroscopy study of elementary magnetic excitations in an
Ising-like antiferromagnetic chain compound SrCoVO as a function of
temperature and applied transverse magnetic field up to 25 T. An optical as
well as an acoustic branch of confined spinons, the elementary excitations at
zero field, are identified in the antiferromagnetic phase below the N\'{e}el
temperature of 5 K and described by a one-dimensional Schr\"{o}dinger equation.
The confinement can be suppressed by an applied transverse field and a quantum
disordered phase is induced at 7 T. In this disordered paramagnetic phase, we
observe three emergent fermionic excitations with different transverse-field
dependencies. The nature of these modes is clarified by studying spin dynamic
structure factor of a 1D transverse-field Heisenberg-Ising (XXZ) model using
the method of infinite time evolving block decimation. Our work reveals
emergent quantum phenomena and provides a concrete system for testifying
theoretical predications of one-dimension quantum spin models.Comment: 8 pages and 6 figure
Hybrid Spectral-IRDx: Near-IR and Ultrasound Attenuation System for Differentiating Breast Cancer from Adjacent Normal Tissue
OBJECTIVE: While performing surgical excision for breast cancer (lumpectomy), it is important to ensure a clear margin of normal tissue around the cancer to achieve complete resection. The current standard is histopathology; however, it is time-consuming and labour-intensive requiring skilled personnel. METHOD: We describe a Hybrid Spectral-IRDx - a combination of the previously reported Spectral-IRDx tool with multimodal ultrasound and NIR spectroscopy techniques. We show how this portable, cost-effective, minimal-contact tool could provide rapid diagnosis of cancer using formalin-fixed (FF) and deparaffinized (DP) breast biopsy tissues. RESULTS: Using this new tool, measurements were performed on cancerous/fibroadenoma and its adjacent normal tissues from the same patients (N=14). The acoustic attenuation coefficient () and reduced scattering coefficient (s) (at 850, 940, and 1060 nm) for the cancerous/fibroadenoma tissues were reported to be higher compared to adjacent normal tissues, a basis of delineation. Comparing FF cancerous and adjacent normal tissue, the difference in s at 850 nm and 940 nm were statistically significant (p=3.17e-2 and 7.94e-3 respectively). The difference in between the cancerous and adjacent normal tissues for DP and FF tissues were also statistically significant (p=2.85e-2 and 7.94e-3 respectively). Combining multimodal parameters and s (at 940 nm) show highest statistical significance (p=6.72e-4) between FF cancerous/fibroadenoma and adjacent normal tissues. CONCLUSION: We show that Hybrid Spectral-IRDx can accurately delineate between cancerous and adjacent normal breast biopsy tissue. SIGNIFICANCE: The results obtained establish the proof-of-principle and large-scale testing of this multimodal breast cancer diagnostic platform for core biopsy diagnosis
Differentially expressed genes in platinum-resistant high-grade serous ovarian cancer
Objectives: The purpose of this study was to identify genes and pathways differentially expressed in platinum resistant high grade serous ovarian cancer (HGSOC) when compared to sensitive HGSOC.
Methods: A total of 37 patients with HGSOC tissue samples underwent RNA sequencing performed by TEMPUS (N=37, 21 platinum sensitive, 16 resistant; 85% Stage III-IV; 58% received neoadjuvant chemotherapy). RNA gene expression data and significantly impacted pathways were analyzed using Advaita Bio\u27s iPathwayGuide. Differentially expressed (DE) genes were identified using FDR of 0.05 and fold-change of 1.5. Genes from several impacted canonical metabolic pathways were validated by PCR against external data sets in a separate ovarian cancer sample group (n=15), platinum resistant ovarian cancer mouse tumor model, and wild-type sensitive and platinum resistant ovarian cancer cell lines. Relative gene expression was calculated using the comparative Ct method, also referred to as the “2 DDCT”, using L27 as internal control gene.
Results: We identified 177 differentially expressed (DE) genes out of a total of 16,607 genes (1.1%) with measured expression. 15 pathways were found to be significantly impacted. Of the 15 canonical pathways, all were up regulated in the resistant HGSOC and the majority of the most significantly altered (5/10) were related to metabolism (Retinol metabolism (p-value = 0.002); Tyrosine Metabolism (p-value = 0.005); Tryptophan Metabolism (p-value = 0.009); and Phenylalanine Metabolism (p-value = 0.012); CYP Drug Metabolism (p-value = 0.022)). A total of 3 separate genes from the CYP family and two from the Dopa Decarboxylase family of genes were validated against an external data set of human ovarian tissue samples, cell lines, mouse ovarian tumor model, and found to have similarly increased gene expression in the genes tested in the platinum resistant groups. Compilation of KEGG analysis and the common network genes revealed pathways associated with amino acid metabolism to be most significantly altered.
Conclusions: We describe the identification of a unique transcriptomic profile associated with platinum resistance. Interestingly, the main pathways identified are related to metabolism, suggesting that the survival to chemotherapy demands a major metabolic adaptation. These findings also represent a first step towards the identification of biomarkers for the detection of chemo-resistant disease and metabolism-based drug targets specific for chemo-resistant tumors. Further validation of this model is required in order to determine its clinical value
- …