Internal noise driven generalized Langevin equation from a nonlocal continuum model

Starting with a micropolar formulation, known to account for nonlocal microstructural effects at the continuum level, a generalized Langevin equation (GLE) for a particle, describing the predominant motion of a localized region through a single displacement degree-of-freedom (DOF), is derived. The GLE features a memory dependent multiplicative or internal noise, which appears upon recognising that the micro-rotation variables possess randomness owing to an uncertainty principle. Unlike its classical version, the new GLE qualitatively reproduces the experimentally measured fluctuations in the steady-state mean square displacement of scattering centers in a polyvinyl alcohol slab. The origin of the fluctuations is traced to nonlocal spatial interactions within the continuum. A constraint equation, similar to a fluctuation dissipation theorem (FDT), is shown to statistically relate the internal noise to the other parameters in the GLE

Ultra-narrow and widely tunable Mn^(2+) Emission from Single Nanocrystals of ZnS-CdS alloy

Extensively studied Mn-doped semiconductor nanocrystals have invariably exhibited photoluminescence (PL) over a narrow energy window of width <= 149 meV in the orange-red region and a surprisingly large spectral width (>= 180 meV), contrary to its presumed atomic-like origin. Carrying out emission measurements on individual single nanocrystals and supported by ab initio calculations, we show that Mn PL emission, in fact, can (i) vary over a much wider range (~ 370 meV) covering the deep green-deep red region and (ii) exhibit widths substantially lower (~ 60-75 meV) than reported so far, opening newer application possibilities and requiring a fundamental shift in our perception of the emission from Mn-doped semiconductor nanocrystals.Comment: 5 pages, 5 figure

Transcriptional profiling and consensus molecular subtype (CMS) assignment to understand response and resistance to anti-EGFR therapy in colorectal cancer

View full abstracthttps://openworks.mdanderson.org/leading-edge/1057/thumbnail.jp

Asymmetric rotations and dimerization driven by normal to modulated phase transition in 4-biphenylcarboxy coupled L-phenylalaninate

Amongst the derivatives of 4-biphenylcarboxylic acid and amino acid esters, the crystal structure of 4-biphenylcarboxy-(L)-phenylalaninate is unusual owing to its monoclinic symmetry within a pseudo-orthorhombic lattice. The distortion is described by disparate rotational property around the chiral centers ($\varphi_{\mathrm{chiral}}$ $\simeq$ -129 degrees and 58 degrees) of the two molecules in the asymmetric unit. Each of these molecules comprise of planar biphenyl moieties ($\varphi_{\mathrm{biphenyl}}$ = 0 degrees). Using temperature dependent single crystal X-ray diffraction experiments we show that the compound undergoes a phase transition below $T$ $\sim$ 124 K that is characterized by a commensurate modulation wave vector, $\mathbf{q}$ = $\delta(101)$, $\delta$ = $\frac{1}{2}$. The (3+1) dimensional modulated structure at $T$ = 100 K suggests that the phase transition drives the biphenyl moieties towards non coplanar conformations with significant variation of internal torsion ($\varphi^{\mathrm{max}}_{\mathrm{biphenyl}}$ $\leq$ $20$ degrees). These intramolecular rotations lead to dimerization of the molecular stacks that are described predominantly by intermolecular tilts and small variations in intermolecular distances. Atypical of modulated structures and superstructures of biphenyl and other polyphenyls, the rotations of individual molecules are asymmetric ($\Delta$$\varphi_{\mathrm{biphenyl}}$ $\approx$ 5 degrees) while $\varphi_{\mathrm{biphenyl}}$ of one independent molecule is two to four times larger than the other. Crystal-chemical analysis and phase relations in superspace suggest multiple competing factors involving intramolecular steric factors, intermolecular H--C${\cdot}{\cdot}{\cdot}$C--H contacts and weak C--H${\cdot}{\cdot}{\cdot}$O hydrogen bonds that govern the distinctively unequal torsional property of the molecules

Appendiceal Adenocarcinoma PDX Models Have Improved Tumor Growth in an Orthotopic Tumor Environment

https://openworks.mdanderson.org/sumexp23/1085/thumbnail.jp

Insulin secretory actions of polyphenols of <i>Momordica charantia</i> regulate glucose homeostasis in alloxan-induced type 2 diabetic rats

Objective Momordica charantia, commonly known as bitter gourd, is traditionally used as remedies for various diseases including diabetes. The main objective of this study is to investigate the in vitro and in vivo insulinotropic and anti-diabetic effects of an 80% ethanolic extract of Momordica charantia (EEMC) fruit, as well as the underlying molecular mechanism involved and preliminary phytochemical screening. Methods The insulin secretion was measured using clonal pancreatic BRIN-BD11 β-cells and isolated mouse islets. The ability of EEMC to inhibit carbohydrate digestive enzymes and glucose absorption and, scavenge free radicals were assessed via starch digestion, glucose diffusion and DPPH assay methods. The effects of EEMC on a variety of metabolic parameters were evaluated in alloxan-induced type 2 diabetic rats, including lipid profile. Finally, a preliminary phytochemical screening was conducted to identify the active phytoconstituents. Key findings EEMC increased insulin release through the KATP-dependent/cAMP pathway, which depolarizes the β-cell membrane and elevates intracellular calcium. It also inhibited glucose absorption and free radicals, suggesting its potential to delay gastric emptying, attenuate oxidative stress, and reduce inflammatory cytokines. In vivo studies showed that EEMC improves oral glucose tolerance, food intake, fasting blood glucose, plasma insulin, lipids, and promotes intestinal motility. The active phytoconstituents in EEMC, such as flavonoids, alkaloids, tannins, saponins, steroids, and glycosides, are likely responsible for these effects. Conclusion The antihyperglycemic properties of EEMC indicate that it might be a promising candidate for diabetes management. However, additional study into the application of Momordica charantia in type 2 diabetes is essential

Goblet Cell Tumors of the Appendix: Clinical & Molecular Features

View full abstracthttps://openworks.mdanderson.org/leading-edge/1047/thumbnail.jp

Utility of plasma tumor marker levels in management of patients with appendiceal adenocarcinoma

View full abstracthttps://openworks.mdanderson.org/leading-edge/1049/thumbnail.jp