The mode-coupling glass transition in a fluid confined by a periodic potential

We show that a fluid under strong spatially periodic confinement displays a glass transition within mode-coupling theory (MCT) at a much lower density than the corresponding bulk system. We use fluctuating hydrodynamics, with confinement imposed through a periodic potential whose wavelength plays an important role in our treatment. To make the calculation tractable we implement a detailed calculation in one dimension. Although we do not expect simple 1d fluids to show a glass transition, our results are indicative of the behaviour expected in higher dimensions. In a certain region of parameter space we observe a three-step relaxation reported recently in computer simulations [S.H. Krishnan, PhD thesis, Indian Institute of Science (2005); Kim et al., Eur. Phys. J-ST 189, 135-139 (2010)] and a glass-glass transition. We compare our results to those of Krakoviack, PRE 75, 031503 (2007) and Lang et al., PRL 105, 125701 (2010).Comment: This is the published version of the paper, minor modification, few more references adde

Performance of a fast fiber based UV/Vis multiwavelength detector for the analytical ultracentrifuge

The optical setup and the performance of a prototype UV/Vis multiwavelength analytical ultracentrifuge (MWL-AUC) is described and compared to the commercially available Optima XL-A from Beckman Coulter. Slight modifications have been made to the optical path of the MWL-AUC. With respect to wavelength accuracy and radial resolution, the new MWL-AUC is found to be comparable to the existing XL-A. Absorbance accuracy is dependent on the light intensity available at the detection wavelength as well as the intrinsic noise of the data. Measurements from single flashes of light are more noisy for the MWL-AUC, potentially due to the absence of flash-to-flash normalization in the current design. However, the possibility of both wavelength and scan averaging can compensate for this and still give much faster scan rates than the XL-A. Some further improvements of the existing design are suggested based on these findings

Anomalous structural evolution and glassy lattice in mixed-halide hybrid perovskites

Hybrid halide perovskites have emerged as highly promising photovoltaic materials because of their exceptional optoelectronic properties, which are often optimized via compositional engineering like mixing halides. It is well established that hybrid perovskites undergo a series of structural phase transitions as temperature varies. In this work, the authors find that phase transitions are substantially suppressed in mixed-halide hybrid perovskite single crystals of MAPbI3-xBrx (MA = CH3NH3+ and x = 1 or 2) using a complementary suite of diffraction and spectroscopic techniques. Furthermore, as a general behavior, multiple crystallographic phases coexist in mixed-halide perovskites over a wide temperature range, and a slightly distorted monoclinic phase, hitherto unreported for hybrid perovskites, is dominant at temperatures above 100 K. The anomalous structural evolution is correlated with the glassy behavior of organic cations and optical phonons in mixed-halide perovskites. This work demonstrates the complex interplay between composition engineering and lattice dynamics in hybrid perovskites, shedding new light on their unique properties.Peer ReviewedPostprint (published version

Minimal information for studies of extracellular vesicles (MISEV2023): From basic to advanced approaches

Extracellular vesicles (EVs), through their complex cargo, can reflect the state of their cell of origin and change the functions and phenotypes of other cells. These features indicate strong biomarker and therapeutic potential and have generated broad interest, as evidenced by the steady year-on-year increase in the numbers of scientific publications about EVs. Important advances have been made in EV metrology and in understanding and applying EV biology. However, hurdles remain to realising the potential of EVs in domains ranging from basic biology to clinical applications due to challenges in EV nomenclature, separation from non-vesicular extracellular particles, characterisation and functional studies. To address the challenges and opportunities in this rapidly evolving field, the International Society for Extracellular Vesicles (ISEV) updates its 'Minimal Information for Studies of Extracellular Vesicles', which was first published in 2014 and then in 2018 as MISEV2014 and MISEV2018, respectively. The goal of the current document, MISEV2023, is to provide researchers with an updated snapshot of available approaches and their advantages and limitations for production, separation and characterisation of EVs from multiple sources, including cell culture, body fluids and solid tissues. In addition to presenting the latest state of the art in basic principles of EV research, this document also covers advanced techniques and approaches that are currently expanding the boundaries of the field. MISEV2023 also includes new sections on EV release and uptake and a brief discussion of in vivo approaches to study EVs. Compiling feedback from ISEV expert task forces and more than 1000 researchers, this document conveys the current state of EV research to facilitate robust scientific discoveries and move the field forward even more rapidly

Effects of Radiotherapy on Ehrlich’s Ascetic Carcinoma in Swiss Albino Mice: An Experimental Study

Background: Experimental tumors have great importance in modeling, and Ehrlich ascites carcinoma (EAC) is one of the most common tumors. EAC is referred to as an undifferentiated carcinoma and is originally hyperdiploid, has high transplantable capability, no-regression, rapid proliferation, shorter life span, 100% malignancy, and also does not have tumor-specific transplantation antigen. The current concepts that radiotherapy alone or with cancer chemotherapy is administered at a dose to the maximum a patient can tolerate before the onset of severe and even life-threatening toxicity is still in wide clinical use. This study was conducted to evaluate the response of radiotherapy in the treatment of EAC. Materials and Methods: A mouse bearing the tumor strain was taken from our laboratory in the Department of Pathology, IPGMER, Kolkata, where the strain was being maintained serially by inoculation of malignant cells into healthy mice every 8–10 days. In our work, altogether 25 mice were taken for each set of experimental work. They were divided in four groups of 5–10 mice in each group. The various parameters to assess the response of various therapeutic schedules were regression of tumor by decrease in body weight of mice and decrease in abdominal girth; cell count of ascetic fluid and morphological changes of tumor cells after treatment with drugs and to study the percentage viability of the cells. Results: All the mice in Group I gained weight steadily. Mice of Group II were unaffected by single dose whole body radiation and they behaved as mice of Group I. All mice of Group III died within 20–25 days. Conclusion: Cell changes were observed but not as marked. Cell viability was as high as 65% after treatment as compared to tumor control which showed a viability of about 75%

Anion tuning of Zn2+ architectures using a Tris-base salicylic ligand

In this study, a hydroxyl-rich Schiff base ligand, HL, and its resulting complexes with ZnCl, Zn(CHCOO) and Zn(ClO) were explored. Interestingly, depending on the zinc salt and/or the crystallisation method, four unique structures were obtained. A synthesis with ZnCl gave 1, a mononuclear structure ((HL)Zn), while with Zn(CHCOO), a trinuclear system [(HL)Zn(CHCOO)], 2, was found. Interestingly two multinuclear architectures were observed with Zn(ClO). Firstly, diethyl ether diffusion of a methanolic reaction mixture with minimal atmospheric air volume gave 3, a hexanuclear architecture of the type [(HL)(HL)Zn](ClO), while slow evaporation of a similar mixture gave 4, a nonanuclear architecture with the formula [(HL)Zn(CO)](ClO). Compound 4 unexpectedly fixed atmospheric CO as CO, incorporating it into the architecture. As expected, a diethyl ether diffusion with a larger volume of air (∼100 mL) of a similar methanolic reaction mixture gave a mixture of 3 and 4. In addition, bulk samples of all compounds were also investigated by PXRD, and results are in good agreement with the observed single crystal data. Furthermore, complexes 1-4 were characterised using FT-IR and simultaneous thermal analysis (STA), and additionally the photophysical properties of HL and complexes 1-4 have also been explored

Direct monitoring of spin transitions in a dinuclear triple-stranded helicate iron(II) complex through X-ray photoelectron spectroscopy

A dinuclear helical iron(ii) complex of a new ditopic thiazolylimine ligand (L) has been synthesised via supramolecular assembly. The resulting dinuclear helical cylinder [Fe2L3].4BF4 was investigated by variable temperature X-ray crystallography, ESI high resolution mass spectrometry, CHN analysis, FT-IR and UV-Vis spectroscopy. The nature of the spin transition was investigated by magnetic susceptibility measurements, and confirmed by VT-SCXRD and X-ray photoelectron spectroscopy. [Fe2L3].4BF4 displays a complete spin transition with a gradual-abrupt character at T1/2 = 348 K and represents a new example of a dinuclear iron(ii) complex exhibiting a spin transition at high temperature. Both VT-SCXRD and XPS measurements show excellent correlation with the magnetic susceptibility experiments, demonstrating the power of XPS not just to confirm, but also to clearly follow the spin-state transition in Fe(ii) SCO complexes

Unique Spin Crossover Pathways Differentiated by Scan Rate in a New Dinuclear Fe(II) Triple Helicate: Mechanistic Deductions Enabled by Synchrotron Radiation Studies

The achievement of targeted properties in spin crossover (SCO) materials is complicated by often unpredictable cooperative interactions in the solid state. Herein, we report a dinuclear Fe(II) triple helicate 1, which is a rare example of a SCO material possessing two distinct magnetic behaviors that depend upon the thermal scan rate. Desolvated 1 was seen to undergo spin transition (ST) which was complete following slow cooling (1 K min-1), but incomplete ST (corresponding to 50% conversion) on fast cooling (10 K min-1). The incomplete ST observed in the latter case was accompanied by a higher temperature onset of ST, differing from TIESST (Temperature-Induced Excited Spin-State Trapping) materials. The two SCO pathways have been shown to arise from the interconversion between two structural phases (a and b), with both phases having associated high spin (HS) and low spin (LS) states. SCXRD (Single Crystal X-ray Diffraction) experiments using controlled cooling rates and a synchrotron light source enabled short collection times (2-3 minutes per dataset) which has enabled the identification of a mechanism by which the slow-cooled material may fully relax. In contrast, fast-cooled materials exhibit disordered arrangements of multiple structural phases, which has in turn revealed that the [HS-LS] ↔ [LS-HS] equilibria are controllable in the solid by varying the scan rate. Such behavior has been previously observed in solution studies, but its control in solids has not been reported up to now. This study demonstrates how intermolecular cooperativity can allow multiple distinct magnetic behaviors, and provides some insight into how [HS-LS] ↔ [LS-HS] equilibria can be controlled in the solid state, which may assist in the design of next-generation logic and signaling devices

Unique spin crossover pathways differentiated by scan rate in a new dinuclear Fe(II) triple helicate : mechanistic deductions enabled by synchrotron radiation studies

The achievement of targeted properties in spin crossover (SCO) materials is complicated by often unpredictable cooperative interactions in the solid state. Herein, we report a dinuclear Fe(II) triple helicate 1 , (single crystals ( 1 ·4(MeCN)5.75(H 2 O)Et 2 O), and air dried bulk samples 1 ·6H 2 O and desolvated 1 ), which represents a rare example of a SCO system possessing two distinct magnetic behaviours that depend upon the thermal scan rate. Desolvated 1 was seen to undergo spin transition (ST) which was complete following slow cooling (1 K min −1 ), but incomplete ST (corresponding to 50% conversion) on fast cooling (10 K min −1 ). The incomplete ST observed in the latter case was accompanied by a higher temperature onset of ST, differing from TIESST (Temperature-Induced Excited Spin-State Trapping) materials. The two SCO pathways have been shown to arise from the interconversion between two structural phases ( a and b ), with both phases having associated high spin (HS) and low spin (LS) states. SCXRD (Single Crystal X-ray Diffraction) experiments of 1 ·4(MeCN)5.75(H 2 O)Et 2 O using controlled cooling rates and a synchrotron light source enabled short collection times (2-3 minutes per dataset) which has enabled the identification of a mechanism by which the slow-cooled material may fully relax. In contrast, fast-cooled materials exhibit disordered arrangements of multiple structural phases, which has in turn revealed that the [HS-LS] ↔ [LS-HS] equilibria are controllable in the solid by varying the scan rate. Such behaviour has been previously observed in solution studies, but its control in solids has not been reported up to now. This study demonstrates how intermolecular cooperativity can allow multiple distinct magnetic behaviours, and provides some insight into how [HS-LS] ↔ [LS-HS] equilibria can be controlled in the solid state, which may assist in the design of next-generation logic and signalling devices