Transmission Electron Microscopy Studies Research Articles

Investigation of the thermal decomposition of Pu(IV) oxalate: a transmission electron microscopy study

The degradation of the internal structure of plutonium (IV) oxalate during calcination was investigated with Transmission Electron Microscopy (TEM), electron diffraction, Electron Energy-Loss Spectroscopy (EELS), and 4D Scanning TEM (STEM). TEM lift-outs were prepared from samples that had been calcined at 300°C, 450°C, 650°C and 950°C. The resulting phase at all calcination temperatures was identified as PuO2 with electron diffraction. The grain size range was obtained with high-resolution TEM. In addition, 4D STEM images were analyzed to provide grain size distributions. In the 300°C calcined sample, the grains were <10 nm in diameter, at 650°C, the grains ranged from 10 to 20 nm, and by 950°C, the grains were 95–175 nm across. Using the Kolmogorov-Smirnov (K-S) two sample test, it was shown that morphological measurements obtained from 4D-STEM provided statistically significant distributions to distinguish samples at the different calcination conditions. Using STEM-EELS, carbon was shown to be present in the low temperature calcined samples associated with oxalate but had formed carbon (possibly graphite) deposits in the 950°C calcined sample. This work highlights the new methods of STEM-EELS and 4D-STEM for studying the internal structure of special nuclear materials (SNM).

Ameliorative Potential of Bone Marrow-Derived Mesenchymal Stem Cells Versus Prednisolone in a Rat Model of Lung Fibrosis: A Histological, Immunohistochemical, and Biochemical Study.

Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease of unknown origin with limited treatment options and poor prognosis. The encouraging findings from preclinical investigations utilizing mesenchymal stem cells (MSCs) indicated that they could serve as a promising therapeutic alternative for managing chronic lung conditions, such as IPF. The objective of this study was to compare the efficiency of bone marrow-derived MSCs (BM-MSCs) versus prednisolone, the standard anti-inflammatory medication, in rats with bleomycin (BLM)-induced lung fibrosis. Four groups were created: a control group, a BLM group, a prednisolone-treated group, and a BM-MSCs-treated group. To induce lung fibrosis, 5 mg/kg of BLM was administered intratracheally. BLM significantly increased serum levels of pro-inflammatory cytokines and oxidative stress markers. The disturbed lung structure was also revealed by light and transmission electron microscopic studies. Upregulation in the immune expression of alpha-smooth muscle actin, transforming growth factor beta-1, and Bax was demonstrated. Interestingly, all findings significantly regressed on treatment with prednisolone and BM-MSCs. However, treatment with BM-MSCs showed better results than with prednisolone. In conclusion, BM-MSCs could be a promising approach for managing lung fibrosis.

Crystal structures of two new high-pressure oxynitrides with composition SnGe4N4O4, from single-crystal electron diffraction.

SnGe4N4O4 was synthesized at high pressure (16 and 20 GPa) and high temperature (1200 and 1500°C) in a large-volume press. Powder X-ray diffraction experiments using synchrotron radiation indicate that the derived samples are mixtures of known and unknown phases. However, the powder X-ray diffraction patterns are not sufficient for structural characterization. Transmission electron microscopy studies reveal crystals of several hundreds of nanometres in size with different chemical composition. Among them, crystals of a previously unknown phase with stoichiometry SnGe4N4O4 were detected and investigated using automated diffraction tomography (ADT), a three-dimensional electron diffraction method. Via ADT, the crystal structure could be determined from single nanocrystals in space group P63mc, exhibiting a nolanite-type structure. This was confirmed by density functional theory calculations and atomic resolution scanning transmission electron microscopy images. In one of the syntheses runs a rhombohedral 6R polytype of SnGe4N4O4 could be found together with the nolanite-type SnGe4N4O4. The structure of this polymorph was solved as well using ADT.

Biochemical and immunomodulatory insights of extracellular matrix from decellularized human whole cervix: recellularization and in vivo ECM remodeling interplay

Extracellular matrix (ECM) rich whole organ bio-scaffolds, preserving structural integrity and essential growth factors, has potential towards regeneration and reconstruction. Women with cervical anomalies or trauma can benefit from clinical cervicovaginal repair using constructs rich in site specific ECM. In this study, complete human cervix decellularization was achieved using a modified perfusion-based stir bench top decellularization method. This was followed by physico-chemical processes including perfusion of ionic agents, enzymatic treatment and washing using detergent solutions for a duration of 10–12 d. Histopathological analysis, as well as DNA quantification confirmed the efficacy of the decellularization process. Tissue ultrastructure integrity was preserved and the same was validated via scanning electron microscopy and transmission electron microscopy studies. Biochemical analysis and structural characterizations like Fourier transform infrared, Raman spectroscopy of decellularized tissues demonstrated preservation of important proteins, crucial growth factors, collagen, and glycosaminoglycans. In vitro studies, using THP-1 and human umbilical vein endothelial cell (HUVEC) cells, demonstrated macrophage polarization from M1 to M2 and vascular functional genes enhancement, respectively, when treated with decellularized human cervical matrix (DHCp). Crosslinked DHC scaffolds were recellularized with site specific human cervical epithelial cells and HUVEC, showing non-cytotoxic cell viability and enhanced proliferation. Furthermore, DHC scaffolds showed immunomodulatory effects in vivo on small rodent model via upregulation of M2 macrophage genes as compared to decellularized rat cervix matrix scaffolds (DRC). DHC scaffolds underwent neo-vascularization followed by ECM remodeling with enhanced tissue integration.

Histochemical and ultrastructural localization of triterpene saponins in Medicago truncatula.

In the Medicago genus, saponins are complex mixtures of triterpene pentacyclic glycosides extensively studied for their different and economically relevant biological and pharmaceutical properties. This research is aimed at determining for the first time the tissue and cellular localization of triterpene saponins in vegetative organs of Medicago truncatula, a model plant species for legumes, by histochemistry and transmission electron microscopy. The results showed that saponins are present mainly in the palisade mesophyll layer of leaves, whereas in stems they are mostly located in the primary phloem and the subepidermal cells of cortical parenchyma. In root tissue, saponins occur in the secondary phloem region. Transmission electron microscopy revealed prominent saponin accumulation within the leaf and stem chloroplasts, while in the roots the saponins are found in the vesicular structures. Our results demonstrate the feasibility of using histochemistry and transmission electron microscopy to localize M. truncatula saponins at tissue and cellular levels and provide important information for further studies on biosynthesis and regulation of valuable bioactive saponins on agronomic relevant Medicago spp., such as alfalfa (Medicago sativa L.). RESEARCH HIGHLIGHTS: The Medicago genus represents a valuable rich source of saponins, one of the most interesting groups of secondary plant metabolites, which possess relevant biological and pharmacological properties. Plant tissue and cellular localization of saponins is of great importance to better understand their biological functions, biosynthetic pathway, and regulatory mechanisms. We elucidate the localization of saponins in Medicago truncatula with histochemical and transmission electron microscopy studies.

SDPR expression in human trabecular meshwork and its potential role in racial disparities of glaucoma

In order to identify how differential gene expression in the trabecular meshwork (TM) contributes to racial disparities of caveolar protein expression, TM dysfunction and development of primary open angle glaucoma (POAG), RNA sequencing was performed to compare TM tissue obtained from White and Black POAG surgical (trabeculectomy) specimens. Healthy donor TM tissue from White and Black donors was analyzed by PCR, qPCR, immunohistochemistry staining, and Western blot to evaluate SDPR (serum deprivation protein response; Cavin 2) and CAV1/CAV2 (Caveolin 1/Caveolin 2). Standard transmission electron microscopy (TEM) and immunogold labeled studies were performed. RNA sequencing demonstrated reduced SDPR expression in TM from Black vs White POAG patients’ surgical specimens, with no significant expression differences in other caveolae-associated genes, confirmed by qPCR analysis. No racial differences in SDPR gene expression were noted in healthy donor tissue by PCR analysis, but there was greater expression as compared to specimens from patients with glaucoma. Analysis of SDPR protein expression confirmed specific expression in the TM regions, but not in adjacent tissues. TEM studies of TM specimens from healthy donors did not demonstrate any racial differences in caveolar morphology, but a significant reduction of caveolae with normal morphology and immuno-gold staining of SDPR were noted in glaucomatous TM as compared to TM from healthy donors. Linkage of SDPR expression levels in TM, POAG development, and caveolar ultrastructural morphology may provide the basis for a novel pathway of exploration of the pathologic mechanisms of glaucoma. Differential gene expression of SDPR in TM from Black vs White subjects with glaucoma may further our understanding of the important public health implications of the racial disparities of this blinding disease.

Synthesis and multifunctional characterizations of Gd2 O3 and Sm2 O3 modified ZnO nanoparticles

In the present communication multifunctional characterizations suitable for spintronics and memory storage devices are described. Double doped (Gd3+, Sm3+) ZnO nanoparticles are prepared from Sol-Gel method using poly vinyl alcohol (PVA) as chelating agent. The as prepared powders are annealed at 500 °C–1000 °C with a step size of 100 °C. The genesis of single phase hexagonal wurtzite structure, morphological and topographical changes, optical, magnetic and mechanical properties were studied with XRD (X-ray diffraction), SEM (scanning electron microscopy), TEM (transmission electron microscopy), EDS (energy dispersive spectroscopy), UV- DRS (ultraviolet diffuse reflective spectroscopy), PL (photoluminescence), VSM (vibrating sample magnetometer) and pin on disc tribometer. XRD study untangled the crystallite size and found to be in the range23-50nm. Polycrystalline nanoparticles of spherical geometry with induced porosity is observed from SEM study. The particle size associated with the samples annealed at 500 °C and 900 °C is 24 nm and 27 nm respectively from TEM study. Analyzed the proximity of functional groups, molecular vibrations in the range of 400-4000 cm−1 employing FTIR (Fourier transform infrared spectroscopy). EDS results revealed the stoichiometry of the produced samples. The pronounced optoelectronic applications of Zn1-x Gdx Smx O (ZGS) can be attributed to the large band gap (3.50–3.02 eV) associated with the materials with rise in annealing temperature. The room temperature ferromagnetism was evidenced with double doped ZnO nanomaterials. The wear coefficient, and friction coefficient were evaluated using pin-on-disc tribometer. The utility of materials as solid state lubricants was confiscated from the range of frictional coefficient values (0.067–0.893).

Enhanced photo-electro catalytic CO2 conversion using transition metal doped TiO2 nanoparticles

The Fe, Co, and Ni-doped TiO2 were synthesised by sol–gel process, and the nanomaterials were coated on electrodes through a slurry with Nafion. This study aims to use prepared nanoparticles of Fe, Co, and Ni-doped TiO2 to enhance the photo-electrocatalytic conversion of CO2. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and electrochemical analyses were utilized to characterise the doped and undoped TiO2 nanoparticles. Transmission electron microscopy (TEM) studies revealed that the nanomaterials had an average size below 20 nm. Tauc plot analysis for optical absorption studies shown a reduction in band gap when doped with Fe, Co and Ni, with the most significant decrease observed for Fe-doped TiO2, following the order Fe < Co < Ni. Electrochemical CO2 conversion efficiencies were investigated through cyclic voltammetry (CV) curves, electrochemical impedance spectroscopy (ESI), and linear sweep voltammetry (LSV) studies. The results were analysed based on various scan rates and photo exposure, indicating superior performance for Fe-TiO2, aligning with the observed band gap trends. Gas chromatography (GC) analysis of the reduction products revealed the generation of hydrocarbons, with Fe-TiO2 exhibiting the most favourable outcomes. This research provides valuable insights into tailoring TiO2 nanoparticles for efficient photo-electro catalytic reduction of CO2.

Advanced modelling tool to extract the structural state boundaries from the hardness-strain experiments

High pressure torsion (HPT) is the way to form nanostructured materials with high strength properties. HPT hardening mechanisms in BCC metals, such as niobium and vanadium, are not fully understood. Here, we have demonstrated that a recently proposed piecewise model can extract from the hardness-strain experimental data the different structural states in BCC metals. The piecewise model, with overlapped stages, is based on an assumption that two separate deformation mechanisms which are responsible for the type of structure have overlapped strain region. To confirm/disprove extracted boundary values, we performed a transmission electron microscopic study of the HPT niobium and vanadium. We found that the piecewise model provides accurate extraction of the boundaries in niobium and vanadium. We proposed an explanation for the observed difference in the structure formation/transformation in niobium and vanadium upon HPT.

Mitochondrial involvement in the metabolic defects evoked by hepatocyte-specific BBSome deficiency

The BBSome, a protein complex of 8 Bardet-Biedl syndrome (BBS) proteins including BBS1, has emerged as an important regulator of metabolic function. BBSome deficient human and mice display several metabolic features including obesity and type 2 diabetes. Here, we show that mice lacking the BBSome specifically in liver which were generated by crossing the Bbs1fl/fl mice with liver-specific (albumin) AlbCre mice exhibit significantly higher lipid droplets in liver, by Oil Red-O staining, and in primary cultured hepatocytes (5.7%±0.4% vs 2.4%±0.6%, control), and by Transmission electron microscope (TEM). AlbCre/Bbs1flox also have elevated fasting glucose (169± 14 vs 136±8 mg/dL, p&lt;0.05) and impaired insulin sensitivity. In addition, insulin-induced activation of AKT was significantly decreased in the liver (2.6±0.07 vs 6.6± 0.34 AU, p&lt;0.05), but not in white adipose tissue and skeletal muscle, of AlbCre/Bbs1flox mice. Using immunohistochemistry, we found that insulin receptor level in plasma membrane was decreased by 24.2±6.8% in primary cultured hepatocytes derived from AlbCre/Bbs1flox mice which explains the insulin resistance. Our previous work implicating the BBSome in the regulation of mitochondria led us to hypothesize that mitochondria dysfunction contributes to the development of metabolic defects in AlbCre/Bbs1flox mice. TEM studies revealed that mitochondria were significantly larger and longer in hepatocytes of AlbCre/Bbs1flox mice than controls. This was associated with decreased levels of Dynamin-related protein 1 (DRP1), which critically regulates mitochondrial function through fission. Next, we asked whether the mitochondrial defects may explain the insulin receptor mistraffcking in BBSome deficient hepatocytes. To test this, hepatocytes were infected with feline immunodeficiency virus that express an active mutant form of DRP1 (FIV-DRP1S637A). Interestingly, insulin receptor localization in the plasma membrane was significantly higher in hepatocytes of Bbs1fl/fl/AlbCre­ mice infected with FIV-DRP1S637A pointing to mitochondrial defects as the underlying cause of insulin receptor mislocalization induced by hepatic BBSome deficiency. Taken together, these findings demonstrate that BBSome regulation of metabolic function involve mitochondria. NIH and VA. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Borides Mn3-x{Rh,Ir}5B2 with Ti3Co5B2-type: X-ray single crystal and TEM data, physical properties.

A cursory investigation of the phase relations in the Mn-{Rh,Ir}-B systems prompted for each system a ternary compound, Mn3-x{Rh,Ir}5B2, the crystal structure of them was determined from X-ray single crystal data to be isotypic with the Ti3Co5B2-type (space group P4/mbm, No. 127). In both cases the Mn-site in 2a at the origin of the unit cell exhibits a significant defect (or Mn/B substitution). As transmission electron microscopy studies confirm the absence of a superstructure related to these defects/disorder. The two phases, Mn3-xRh5B2 (x∼0.34) and Mn3-xIr5B2 (x∼0.85) at 950°C show rather limited homogeneity regions pointing towards higher Mn-contents. Whereas temperature dependent magnetization and specific heat measurements of Mn2.15Ir5B2 do not reveal any indication for a magnetic phase transition in the temperature range from 3 to 300 K, a broad specific heat anomaly at around 200 K and a tilde shape of the temperature dependent magnetization of Mn2.66Rh5B2 appears indicative of an antiferromagnetic phase transition. The latter is also reflected by an anomaly of the electrical resistivity (ρ; 4 to 300 K) of Mn2.66Rh5B2 which displays a non-monotonous temperature dependence, whereas ρ(T) of Mn2.15Ir5B2 displays a simple metallic-like behavior dominated by scattering from defects. Elastic moduli and Poisson’s ratio were determined at room temperature from Resonant Ultrasonic Spectroscopy (RUS) data yielding Young's moduli of E ∼ 170 GPa for Mn2.66Rh5B2 and E ∼ 210 GPa for Mn2.15Ir5B2. Vickers hardness HV is lower for Mn2.66Rh5B2 (HV = 590 ≅ 5.79 GPa) than for Mn2.15Ir5B2 (HV = 655 ≅ 6.42 GPa). The indentation fracture toughness for Mn2.15Ir5B2 was IKC = 0.71±0.5 MPa m1/2.

Influences of morphology, cation distribution and surface spin canting on magnetic and hyperfine properties of mechanically activated and subsequently heat treated nanosized Co0.8Zn0.2Fe2O4 exhibiting excellent catalytic activity

Herein, we have shown that the particle size, cation redistribution, interparticle interactions, surface spin disorder and strain induced anisotropy play a pivotal role in shaping the magnetic and hyperfine properties of nanosized Co0.8Zn0.2Fe2O4 samples prepared by coprecipitation method followed by high energy ball milling and subsequent thermal treatment. Three samples with different particle size viz., 23 nm (CZ1), 34 nm (CZ2) and 42 nm (CZ3) are characterized by powder x-ray diffraction, transmission electron microscopy and energy dispersive x-ray spectroscopy studies. The samples are well-crystalline, single-phase spinel with appropriate stoichiometry, assorted size and shape. All three samples are magnetically ordered at 300 K with MSAT and HC values 75.22, 81.07, 82.89 emu g−1, respectively, and 530, 460, 420 Oe, respectively. The values of coercivity at 10 K are remarkably high. Cation distribution of CZ1, CZ2 and CZ3 as estimated by taking into account the results of infield Mössbauer spectroscopic study and powder x-ray diffraction in conjugation are: (Co0.272+Zn0.202+Fe0.533+)A[Co0.532+Fe1.473+]BO4 (core region of CZ1), (Co0.432+Zn0.202+Fe0.373+)A,[Co0.372+Fe1.633+]BO4 (shell region of CZ1), (Co0.282+Zn0.202+Fe0.523+)A[Co0.522+Fe1.483+]BO4 and (Co0.242+Zn0.202+Fe0.563+)A[Co0.562+Fe1.443+]BO4, respectively. Further, this result has been validated theoretically. Owing to the core-shell structure (ferrimagnetically ordered core surrounded by a disordered shell), sample CZ1 having particle size below calculated critical diameter (∼ 27 nm) exhibits exchange bias effect. All three samples display excellent catalytic activity in the multicomponent reaction for the synthesis of coumarin-3-carboxamide. CZ1 shows best catalytic activity owing to its high surface to volume ratio.

Berberine HCl and diacerein loaded dual delivery transferosomes: Formulation and optimization using Box-Behnken design

Introduction: Berberine is a poorly water-soluble alkaloid compound showing significant anti-inflammatory characteristics. It reduces the levels of pro-inflammatory and inflammatory cytokines, including tumour necrosis factor (TNF-????, IFN-????) and interleukin (IL-23, IL-12, and IL-23). Diacerein significantly reduces the splenomegaly associated with psoriasis. It downregulates the production of TNF-α and IL-12. Method: This study reported the development of transferosomes containing berberine HCl and diacerein using a film hydration method followed by optimization using a Box-Behnken design. Sodium deoxycholate was used as an edge activator. The impact of independent variables (amount of phosphatidylcholine, amount of edge activator, and sonication cycles) on dependent variables (particle size and entrapment efficiency) was examined. The optimized formulation was characterized for polydispersity index, vesicle size, entrapment efficiency, ζ potential, spectral analysis like Fourier transform infrared, thermal analysis, X-ray diffraction, deformability, transmission electron microscopy, antioxidant assay, in-vitro release, and ex-vivo skin permeation studies. Results: The optimized formulation had a particle size of 110.90±2.8 nm with high entrapment efficiency (89.50±1.5 of berberine HCl and 91.23±1.8 of diacerein). Deformability, polydispersity index, ζ potential, and antioxidant activity of the optimized formulation were 2.44, 0.296, -13.3, and 38.36 %, respectively. Optimized transferosomes exhibited 82.093±0.81 % and 85.02±3.81 % release of berberine HCl and diacerein after 24 h of dissolution study. The transdermal flux of optimized formulation was 0.0224 µg cm-2 h-1 (2.24 cm h-1 permeation coefficient) and 0.0462 µg cm-2 h-1 (4.62 cm h-1 permeation coefficient), respectively, for berberine HCl and diacerein. Raman analysis of treated pig skin confirmed that the transferosomes can permeate the skin. No change in the skin condition or irritation was observed in BALB/c mice. Formulation stored at 4 and 25±2 °C / 60±5 % relative humidity was stable for 3 months. Conclusions: Thus, the results demonstrated successful optimization of the transferosomes for the efficient topical delivery of berberine HCl and diacerein in the effective management of psoriasis.

Sustainable hybrid green nanofiller based on cellulose nanofiber for enhancing the properties of epoxy resin

Herein, a novel hybrid nano filler (CNF/cloisite 30B) for epoxy was designed and developed from cellulose nanofiber (CNF) and montmorillonite clay (cloisite 30B). The hybrid nanofiller has a morphology of exfoliated clay layers inside fibrous network of CNF as evident by transmission electron microscopy (TEM) and X-ray diffraction (XRD) studies. The crystallinity index of hybrid nanofiller was calculated as 17% from Segal equation. Upon incorporation of hybrid nanofiller, thermal, mechanical and flame-retardant properties of the epoxy was simultaneously increased. A surge in the impact strength (101%) was observed for epoxy/0.5 hybrid nanocomposites. Fracture toughness of the epoxy increases with the addition of hybrid nanofiller, 0.5 phr loading shows the maximum fracture toughness value. Besides this, inclusion of hybrid nanofiller makes the fracture surface of epoxy rougher as confirmed by field emission scanning electron microscopy (FESEM). A significant improvement in the glass transition temperature (Tg) was observed for the fabricated epoxy/hybrid nanocomposites. Compared to pristine epoxy, about 16% and 10% improvement in Tg was observed for 0.5 phr and 1.0 phr CNF/cloisite30 B hybrid loading, respectively. Well-dispersed hybrid nanofiller in the epoxy matrix and the resulting filler matrix interaction restrict the chain mobility by forming several constrained regions in the nanocomposites, which in turn enhances the glass transition temperature of the hybrid nanocomposites. Hybrid nanocomposites exhibited remarkable flame retardancy due to the formation of thick char layer and the reduction in the total heat released (THR) was 34% and 20% compared to neat epoxy resin. The current work ensures that the developed hybrid green filler can be a potential, low cost, and eco-friendly reinforcing agent for polymers.

Green synthesis of Nyctanthes arbor-tristis flower-decorated gold nanoparticles: Sustainable approaches for enhancing antimicrobial and supercapacitor performance

The physiochemical and electrochemical characteristics of gold nanoparticles (AuNPs) produced by phytosynthesis technique at varying concentrations of Nyctanthes arbor-tristis flower (NAF) are presented in this study. The final porous carbon decorated AuNPs have possible applications in antibacterial research as well as energy storage field. Transmission electron microscopy (TEM) studies revealed tiny spherical shaped nanoparticles, and UV–visible spectroscopy showed size-dependent optical properties. Significant antibacterial efficacy against Pseudomonas aeruginosa was shown by the NAF-derived AuNPs. A symmetric supercapacitor with 64 F g−1 specific capacitance at 1 A g−1 and 97% cycling stability after 5000 charge-discharge cycles was produced using the as-synthesized electrode. This study provides a sustainable method for producing multifunctional nanomaterials by highlighting the potential of NAF-derived AuNPs for dual applications in the antibacterial and supercapacitor areas.

Tau-borides (Mnx{Ru,Os,Ir}1-x)23B6: X-ray single crystal and TEM data, physical properties

Investigation (electron microprobe and X-ray powder and single crystal diffraction analyses) of the phase relations in the Mn-rich corner (> 45 at% Mn) of the systems Mn-{Ru,Os,Ir}-B, prompted in all three systems a ternary compound with formula (Mnx{Ru,Os,Ir}1-x)23B6. For the systems Mn-Ru-B, Mn-Ir-B phase equilibria have been determined at 950°C (Ru), 900°C (Ir) revealing in both cases a small homogeneity region at constant B-content (Mn1-xRux)23B6 (0.29 < x < 0.37); (Mn1-xOsx)23B6 (0.33 < x < 0.37), as well as (Mn1-xIrx)23B6 (0.29 < x < 0.34). The crystal structure of the three compounds was determined from single crystal and X-ray powder intensity data analyses to be isotypic with the Cr23B6-type (so-called tau-phase, space group Fm3¯m, No. 225). In all cases Mn atoms fully occupy the 4a site (0,0,0) at the origin of the unit cell. For the 8c site (¼,¼,¼) we observed a random distribution of Mn1-x(PM)x with decreasing PM content (PM stands for a platinum group metal atom) going from Ru to Os and Ir, where Mn atoms fully occupy 8c. Whereas the remaining sites (48h, 32f) show various ratios of the two metal species, boron atoms fully occupy the centers (24e site) of the Archimedean metal atom antiprisms. A transmission electron microscopic study confirms the absence of superstructures related to these metal atom disorder, thus Mn and PM atoms randomly share their sites. The latter is well reflected in the behavior of the electrical resistivity of these compounds, which is dominated by disorder scattering. For (Mn0.6{Ru,Os}0.4)23B6, temperature dependent dc magnetization studies reveal distinct antiferromagnetic-like anomalies at TN ≅ 72 K and 114 K, respectively. Low field dc and ac magnetic susceptibility data of (Mn0.7Ir0.3)23B6 display a distinct ferromagnetic-like transition at TC = 280 K, consistent with a pronounced specific heat anomaly and a rather continuous temperature dependent evolution of magnetic anisotropy effects. Mechanical properties (hardness) characterize the tau phases among rather hard and brittle intermetallics (about 5–6 GPa).

Ultrastructural, molecular and haemato-immunological changes: Multifaceted toxicological effects of microcystin-LR in rohu, Labeo rohita

No water body is resilient to afflicts of algal bloom, if goes unmanaged. With the increasing trend of intensification, eutrophication and climate change, Labeo rohita (rohu) is highly anticipated to suffer from the deleterious effects of bloom and eventually its toxins. A comprehensive study was conducted to understand the toxicopathological effects of microcystin-LR (MC-LR) in rohu following intraperitoneal injection of 96 h-LD50 dose i.e., 713 μg kg−1. Substantial changes in micro- and ultrastructural level were evident in histopathology and transmission electron microscope (TEM) study. The haematological, biochemical, cellular and humoral innate immune biomarkers were significantly altered (p < 0.05) in MC-LR treated fish. The mRNA transcript levels of IL-1β, IL-10, IgM and IgZ in liver and kidney tissues were significantly up-regulated in 12 hpi and declined in 96 hpi MC-LR exposed fish. The relative mRNA expression of caspase 9 in the liver and kidney indicates mitochondrial-mediated apoptosis which was strongly supported by TEM study. In a nutshell, our study illustrates for the first time MC-LR induced toxicological implications in rohu displaying immunosuppression, enhanced oxidative stress, pathophysiology, modulation in mRNA transcription, genotoxicity, structural and ultrastructural alterations signifying it as a vulnerable species for MC-LR intoxication.

Oligomerization states of the Mycobacterium tuberculosis RNA polymerase core and holoenzymes.

During the past few decades, a wealth of knowledge has been made available for the transcription machinery in bacteria from the structural, functional and mechanistic point of view. However, comparatively little is known about the homooligomerization of the multisubunit M. tuberculosis RNA polymerase (RNAP) enzyme and its functional relevance. While E. coli RNAP has been extensively studied, many aspects of RNAP of the deadly pathogenic M. tuberculosis are still unclear. We used biophysical and biochemical methods to study the oligomerization states of the core and holoenzymes of M. tuberculosis RNAP. By size exclusion chromatography and negative staining Transmission Electron Microscopy (TEM) studies and quantitative analysis of the TEM images, we demonstrate that the in vivo reconstituted RNAP core enzyme (α2ββ'ω) can also exist as dimers in vitro. Using similar methods, we also show that the holoenzyme (core + σA) does not dimerize in vitro and exist mostly as monomers. It is tempting to suggest that the oligomeric changes that we see in presence of σA factor might have functional relevance in the cellular process. Although reported previously in E. coli, to our knowledge we report here for the first time the study of oligomeric nature of M. tuberculosis RNAP in presence and absence of σA factor.

OSW-1 triggers necroptosis in colorectal cancer cells through the RIPK1/RIPK3/MLKL signaling pathway facilitated by the RIPK1-p62/SQSTM1 complex.

Necroptosis has emerged as a novel molecular pathway that can be targeted by chemotherapy agents in the treatment of cancer. OSW-1, which is derived from the bulbs of Ornithogalum saundersiae Baker, exerts a wide range of pharmacological effects. To explore whether OSW-1 can induce necroptosis in colorectal cancer (CRC) cells, thereby expanding its range of clinical applications. We performed a sequence of functional experiments, including Cell Counting Kit-8 assays and flow cytometry analysis, to assess the inhibitory effect of OSW-1 on CRC cells. We utilized quantitative proteomics, employing tandem mass tag labeling combined with liquid chromatography-tandem mass spectrometry, to analyze changes in protein expression. Subsequent bioinformatic analysis was conducted to elucidate the biological processes associated with the identified proteins. Transmission electron microscopy (TEM) and immunofluorescence studies were also performed to examine the effects of OSW-1 on necroptosis. Finally, western blotting, siRNA experiments, and immunoprecipitation were employed to evaluate protein interactions within CRC cells. The results revealed that OSW-1 exerted a strong inhibitory effect on CRC cells, and this effect was accompanied by a necroptosis-like morphology that was observable via TEM. OSW-1 was shown to trigger necroptosis via activation of the RIPK1/RIPK3/MLKL pathway. Furthermore, the accumulation of p62/SQSTM1 was shown to mediate OSW-1-induced necroptosis through its interaction with RIPK1. We propose that OSW-1 can induce necroptosis through the RIPK1/RIPK3/MLKL signaling pathway, and that this effect is mediated by the RIPK1-p62/SQSTM1 complex, in CRC cells. These results provide a theoretical foundation for the use of OSW-1 in the clinical treatment of CRC.

Facile combustion-synthesis, structural, morphological, vibrational, photoluminescence, dielectric, and electrical properties of ZnFe2O4 nanostructures: an effect of citric acid concentrations

In the current report, we have facilely synthesized the ZnFe2O4 nanoparticles (ZFO NPs) using the flash combustion route at 600 °C with various concentrations of citric acid (CA). The structural, vibrational, and elemental/homogeneity analyses through XRD, Raman, and energy dispersive X-ray spectroscopy/Scanning electron microscopy e-mapping confirmed the cubic phase and composition of synthesized ZFO NPs. The crystallite size was estimated using Scherrer and Williamson-Hall plot methods and noticed to be reduced with an increasing amount of CA in ZFO and found between 15 and 30 nm, which was also supported by scanning electron and transmission electron microscopic studies. X-ray photoelectron spectroscopy analysis confirmed the synthesis of ZnFe2O4. The ZFO NPs were excited at 417 nm to record the luminescence spectra and found the emission peaks at 456±2, 530±3, and 625±5 nm. The dielectric constant was found to be between 147 and 165 with low loss values, and the electrical conductivity was found to be enhanced with CA content in ZFO NPs. The magnetic properties were also studied at 300 K and disused. These outcomes indicate that the properties of ZFO NPs have been greatly influenced by crystallite/grain size variation, which resulted from different CA concentration-assisted synthesis of ZFO and possess the potential for optoelectronic and energy storage devices.