Monitoring structural fluctuations of discotic liquid crystal during phase transitions.

The discotic liquid crystal 4-((2, 3, 4-tris (octyloxy) phenyl) diazenyl) benzoic acid, hereafter referred as DLC A8, exhibited in dimeric form has been studied using a combination of quantum chemical approaches and vibrational spectroscopy. This study investigates the structural alteration of DLC A8 associated with phase transition. The phase transitions of DLC A8 are Iso â†’ Discotic nematic â†’ Columnar â†’ Crystalline, which have been investigated using differential scanning calorimetry (DSC) accompanied with polarized optical microscopy (POM). Monotropic columnar mesophase was observed during the cooling cycle while discotic nematic mesophase was observed in both the heating and cooling cycles. Density functional theory (DFT) along with IR and Raman spectroscopic techniques were utilized to study the dynamics of molecules during phase transition. To predict the most stable conformation of the molecule, one-dimensional PES scans have been performed along 31 flexible bonds using DFT/B3LYP/6-311G++(d,p) method. Vibrational normal modes were analyzed in detail, taking potential energy contribution into account. The spectral analysis of FT-IR and FT-Raman was done by deconvoluting the structural sensitive bands. The agreement between the calculated IR and Raman spectra and the observed FT-IR and Raman spectra at room temperature confirms our theoretically predicted molecular model of investigated discotic liquid crystal. Moreover, our studies have unraveled the existence of intact intermolecular H-bonding of dimers throughout the phase transitions.

Lived Experiences of Mistreatment in a General Surgery Residency.

OBJECTIVE: Explore the lived experiences of General Surgery residents to identify how they perceive, define mistreatment, and which factors can contribute to or mitigate mistreatment within the Clinical Learning Environment. DESIGN: This is a phenomenological study conducted during 2019-2020 using Giorgi's psychological descriptive phenomenology methodology. Researcher bias, trustworthiness, and triangulation were addressed using bracketing, check-ins with program leadership, comparisons to resident survey, and team consensus based on Consensual Qualitative Research. SETTING: General Surgery Residency program at Long School of Medicine, UT Health San Antonio, Texas. PARTICIPANTS: All residents in the general surgery program were invited to participate (n= 66, 43% female and 63% non-Hispanic). Specific demographic and identifying data for each participant was not collected. Approximately 50 (76% of program) residents from General Surgery participated. RESULTS: We were able to identify four themes that helped to delineate the lived experience of residents including program cultural factors, resident internal processing, and perceived effects of mistreatment by the residents. The resulting psychological structure and conceptual framework help clarify the interrelations between the themes and the Clinical Learning Environment. The scenarios discussed were adapted and depersonalized to use as prompts for the Forum Theater intervention. This project set out to explore resident's lived experiences and allow the data to reveal the main outcomes. The data was coded and analyzed following strict guidelines from descriptive psychological phenomenology and Consensual Qualitative Research with the aim of informing a later experiential intervention based on Forum Theater. CONCLUSIONS: The lived experience of general surgery residents helped identify cultural factors and behaviors that contribute to and/or mitigate mistreatment providing information to plan interventions at the resident and faculty level. Mitigating or stopping mistreatment can improve the Clinical Learning Environment and hence, the quality of training.

Glacier mass balance estimation in Garhwal Himalaya using improved accumulation area ratio method.

Water requirements of the mountain communities living in the Himalaya are supported by snow and glacier melt. The availability of water from the source depends on numerous climatic and glacier parameters. One key parameter is mass balance, which helps to assess the glacier health and future water availability. We have used the improved accumulation area ratio (IAAR) method to estimate mass balance in Alaknanda and Bhagirathi basins, constituting 1055 glaciers covering ~1609 km2. The mean Equilibrium Line Altitude (ELA) of the Alaknanda and Bhagirathi basins are estimated as 6147 ± 130 and 5985 ± 130 m.a.s.l, respectively. The mass balance is estimated using the accumulation area ratio (AAR)-mass balance relationship. The mean specific mass balance of the Alaknanda and Bhagirathi for 2001-2013 is estimated as -1.1 ± 0.03 m.w.e.a-1 and -1.01 ± 0.07 m.w.e.a-1, respectively. Total mass loss from the study area is calculated as ~21.4 ± 1.1Gt during this period. The loss of glaciers in the mountain area will increase the vulnerability of communities living in the region. It suggests a need for better adaptation strategies to improve the resilience of high mountain communities.

Lived experience of medical veterans transitioning from military service to civilian nursing education.

BACKGROUND: Many veterans take advantage of the educational benefits afforded them after service. As veterans, students in higher education are a special population with subsequent needs. PURPOSE: The purpose of this study was to explore the lived experience of medic student veterans attending a full-time Bachelor of Science in Nursing (BSN) program. METHOD: This study used the hermeneutic phenomenology research approach to explore the lived experiences of student veterans with military medic experience enrolled in a Bachelor of Science in Nursing (BSN) program. RESULTS: While our study revealed diverse student experiences among these veterans, common themes included staying true to military training, normal life, and fitting in as a university student. CONCLUSIONS: Findings in this study substantiate medic student veterans attending nursing school represent a unique cohort which can benefit from customized services from the university.

Pseudopolar smectic-C phases of azo-substituted achiral bent-core hockey-stick-shaped molecules.

We report experimental studies on an azo-substituted compound consisting of bent-core hockey-stick-shaped molecules. The experimental results establish two pseudopolar tilted smectic phases, which are characterized by an in-plane axial-vector order parameter in addition to tilt order in the smectic layers. Electro-optical measurements in the mesophases indicate that the birefringence of the sample strongly depends on the applied electric field. We develop a theoretical model to account for this observation. The change in the birefringence of the sample arises from the field-induced reorientation of the tilt plane of the molecules in the layer above a threshold field. The effect is analogous to the field-induced Freedericksz transition which is quadratic in the applied electric field.

Ferroelectric Nematic and Ferrielectric Smectic Mesophases in an Achiral Bent-Core Azo Compound.

Here, we report the observation of ferroelectric nematic and ferrielectric smectic mesophases in an achiral bent-core azo compound consisting of nonsymmetrical molecules with a lateral fluoro substitution on one of the wings. These mesophases are enantiotropic in nature with fairly low transition temperatures and wide mesophase ranges. The liquid crystalline properties of this compound are investigated using polarizing optical microscope, differential scanning calorimeter, X-ray diffraction, and electro-optical studies. As revealed by X-ray diffraction measurements, the nematic mesophase is composed of skewed cybotactic clusters and, in the smectic mesophase, the molecules are tilted with respect to the layer normal. The polar order in these mesophases was confirmed by the electro-optical switching and dielectric spectroscopy measurements. The dielectric study in the nematic mesophase shows a single relaxation process at low frequency ( f < 1 kHz) measured in the range 10 Hz to 5 MHz, which is attributed to the collective motion of the molecules within cybotactic clusters. The formation of local polar order in these clusters leads to a ferroelectric-like polar switching in the nematic mesophase. Of particular interest is the fact that the smectic phase exhibits a field induced ferrielectric state, which can be exploited for designing of the potential optical devices due to multistate switching.

Phase transition analysis of V-shaped liquid crystal: Combined temperature-dependent FTIR and density functional theory approach.

Temperature-dependent Fourier transform infrared spectroscopy (FTIR) combined with density functional theory (DFT) is employed to study the mechanism of phase transitions of V-shaped bent-core liquid crystal. Since it has a large number of flexible bonds, one-dimensional potential energy scan (PES) was performed on the flexible bonds and predicted the most stable conformer I. A detailed analysis of vibrational normal modes of conformer I have been done on the basis of potential energy distribution. The good agreement between the calculated spectrum of conformer I and observed FTIR spectrum at room temperature validates our theoretical structure model. Furthermore, the prominent changes observed in the stretching vibrational bands of CH3/CH2, CO, ring CC, ring CO, ring CH in-plane bending, and ring CH out-of-plane bending at Iso→nematic phase transition (at 155°C) have been illustrated. However, the minor changes in the spectral features observed for the other phase transitions might be due to the shape or bulkiness of molecules. Combined FTIR and PES study beautifully explained the dynamics of the molecules, molecular realignment, H-bonding, and conformational changes at the phase transitions.

Effect of CH-35, a novel anti-tumor colchicine analogue, on breast cancer cells overexpressing the ßIII isotype of tubulin.

The subunit protein of microtubules is tubulin, which has been the target for some of the most successful and widely used anti-tumor drugs. Most of the drugs that target tubulin bind to the ß subunit. There are many isotypes of ß-tubulin and their distributions differ among different tissues. The ßIII isotype is over-expressed in many tumors, particularly those that are aggressive, metastatic, and drug resistant. We have previously reported the design and synthesis of a series of compounds to fit the colchicine site on ßIII but not on the other isotypes. In the current study, we tested the toxicity and the anti-tumor activity of one of these compounds, CH-35, on the human breast tumor MDA-MB-231 over-expressing ßIII in a xenogeneic mouse model. We found that CH-35 was as toxic as Taxol® in vivo. Although the ßIII-over-expressing cells developed into very fast-growing tumors, CH-35 was more effective against this tumor than was Taxol. Our results suggest that CH-35 is a promising candidate for future drug development.

The G protein-coupled oestrogen receptor 1 agonist G-1 disrupts endothelial cell microtubule structure in a receptor-independent manner.

The G protein-coupled oestrogen receptor GPER1, also known as GPR30, has been implicated in oestrogen signalling, but the physiological importance of GPER1 is not fully understood. The GPER1 agonist G-1 has become an important tool to assess GPER1-mediated cellular effects. Here, we report that this substance, besides acting via GPER1, affects the microtubule network in endothelial cells. Treatment with G-1 (3 µM) for 24 h reduced DNA synthesis by about 60 % in mouse microvascular endothelial bEnd.3 cells. Treatment with 3 µM G-1 prevented outgrowth of primary endothelial cells from mouse aortic explants embedded in Matrigel. Treatment with G-1 (0.3-3 µM) for 24 h disrupted bEnd.3 cell and HUVEC microtubule structure in a concentration-dependent manner as assessed by laser-scanning confocal immunofluorescence microscopy. G-1-induced (3 µM) disruption of microtubule was observed also after acute (3 and 6 h) treatment and in the presence of the protein synthesis inhibitor cycloheximide. Disruption of microtubules by 3 µM G-1 was observed in aortic smooth muscle cells obtained from both GPER1 knockout and wild-type mice, suggesting that G-1 influences microtubules through a mechanism independent of GPER1. G-1 dose dependently (10-50 µM) stimulated microtubule assembly in vitro. On the other hand, microtubules appeared normal in the presence of 10-50 µM G-1 as determined by electron microscopy. We suggest that G-1-promoted endothelial cell anti-proliferation is due in part to alteration of microtubule organization through a mechanism independent of GPER1. This G-1-promoted mechanism may be used to block unwanted endothelial cell proliferation and angiogenesis such as that observed in, e.g. cancer.

Raman scattering study of phase biaxiality in a thermotropic bent-core nematic liquid crystal.

Polarized Raman spectroscopy was used to investigate the development of orientational order and the degree of phase biaxiality in a bent-core mesogenic system. The values of the uniaxial order parameters and , and biaxial order parameters , , and , and their evolution with temperature were determined. The temperature dependence of almost all order parameters reveals a second order transition from the uniaxial to biaxial nematic phase with increasing to ∼0.22 before a first order transition to the smectic-C phase, upon cooling.

Role of molecular structure on X-ray diffraction in uniaxial and biaxial phases of thermotropic liquid crystals.

X-ray diffraction is one of the most definitive methods to determine the structure of condensed matter phases, and it has been applied to unequivocally infer the structures of conventional calamitic and lyotropic liquid crystals. With the advent of bent-core and tetrapodic mesogens and the discovery of the biaxial nematic phase in them, the experimental results require more careful interpretation and analysis. Here, we present ab-initio calculations of X-ray diffraction patterns in the isotropic, uniaxial nematic, and biaxial nematic phases of bent-core mesogens. A simple Meier-Saupe-like molecular distribution function is employed to describe both aligned and unaligned mesophases. The distribution function is decomposed into two, polar and azimuthal, distribution functions to calculate the effect of the evolution of uniaxial and biaxial nematic orientational order. The calculations provide satisfactory semiquantitative interpretations of experimental results. The calculations presented here should provide a pathway to more refined and quantitative analysis of X-ray diffraction data from the biaxial nematic phase.

Localization of betav tubulin in the cochlea and cultured cells with a novel monoclonal antibody.

Tubulin, the dimeric structural protein of microtubules, is a heterodimer of alpha and beta subunits; both alpha and beta exist as numerous isotypes encoded by different genes. In vertebrates the sequence differences among the beta(I), beta(II), beta(III), beta(IV) and beta(V) isotypes are highly conserved in evolution, implying that the isotypes may have functional significance. Isotype-specific monoclonal antibodies have been useful in determining the cellular and sub-cellular distributions and possible functions of the beta(I), beta(II), beta(III), and beta(IV) isotypes; however, little is known about the beta(V) isotype. We here report the creation and purification of a monoclonal antibody (SHM.12G11) specific for beta(V). The antibody was designed to be specific for the C-terminal sequence EEEINE, which is unique to rodent and chicken beta(V). The antibody was found to bind specifically to the C-terminal peptide EEEINE, and does not cross-react with the carboxy-termini of either alpha-tubulin or the other beta-tubulin isotypes. However, the antibody also binds to the peptide EEEVNE, but not to the peptide EEEIDG, corresponding respectively to the C-terminal peptides of bovine and human beta(V). Immunofluorescence analysis indicates that beta(V) is found in microtubules of both the interphase network and the mitotic spindle. In gerbils, beta(V) also occurs in the cochlea where it is found largely in the specialized cells that are unique in containing bundled microtubules with 15 protofilaments.

Thermotropic uniaxial and biaxial nematic and smectic phases in bent-core mesogens.

Two azo substituted achiral bent-core mesogens have been synthesized. Optical polarizing microscopy and synchrotron X-ray scattering studies of both compounds reveal the existence of the thermotropic uniaxial and biaxial nematic and three smectic phases at different temperatures in these single component small molecule systems. The transition from the uniaxial to biaxial nematic phase is confirmed to be second order. The transitions from the biaxial nematic to the underlying smectic phase and between the smectic phases have barely discernible heat capacity signatures and thus are also second order.