Clinicopathological profile of ependymomas with special reference to survival data - Experiences of a tertiary care center'.

BACKGROUND AND AIMS: Ependymomas exhibit heterogeneity across age, location, histology, molecular nature and survival suggestive of an epigenetic component in its pathogenesis. The CNS WHO classification (2021) classifies ependymomas based on DNA methylation profiles. Studies suggest that molecular sub-types remain stable throughout the course of disease. Immunohistochemical expression of L1CAM, has been identified as a surrogate marker for ZFTA/c11orf95-RELA fusion in supratentorial ependymomas. This study aims at realising its utility specially in resource-poor setups. MATERIALS AND METHODS: Forty-three histopathologically-proven cases of ependymoma under treatment over the period of three years were selected. Histopathological examination followed by routine IHC staining for GFAP, S-100, EMA and Ki-67 in all cases and L1CAM in the supratentorial ependymomas was done. We have followed-up almost all cases during our study period and was correlated with the IHC expression patterns and clinico-pathological parameters, including survival. RESULTS: In our study the commonest location for ependymomas was spine in adults and posterior fossa in pediatric age group. Majority cases belonged to CNS WHO Grade 2 both in adults and in the paediatric age group. Supratentorial location of ependymomas with positive immuno-reactivity for L1CAM and a higher Ki-67 labelling index were associated with poor survival. CONCLUSION: Our study revealed that L1CAM is an effective surrogate marker for supratentorial ependymomas possibly carrying the ZFTA Fusion gene product. The L1CAM immuno-reactivity also corresponded with the survival data. However, larger population-based studies are required to validate these results further.

Unusual Dzyaloshinskii-Moriya Interaction in Graphene/Fe3GeTe2 Van der Waals Heterostructure.

Dzyaloshinskii-Moriya interaction (DMI) is shown to induce a topologically protected chiral spin texture in magnetic/nonmagnetic heterostructures. In the context of van der Waals spintronic devices, graphene emerges as an excellent candidate material. However, due to its negligible spin-orbit interaction, inducing DMI to stabilize topological spins when coupled to 3d-ferromagnets remains challenging. Here, it is demonstrated that, despite these challenges, a sizeable Rashba-type spin splitting followed by significant DMI is induced in graphene/Fe3GeTe2. This is made possible due to an interfacial electric field driven by charge asymmetry together with the broken inversion symmetry of the heterostructure. These findings reveal that the enhanced DMI energy parameter, resulting from a large effective electron mass in Fe3GeTe2, remarkably contributes to stabilizing non-collinear spins below the Curie temperature, overcoming the magnetic anisotropy energy. These results are supported by the topological Hall effect, which coexists with the non-trivial breakdown of Fermi liquid behavior, confirming the interplay between spins and non-trivial topology. This work paves the way toward the design and control of interface-driven skyrmion-based devices.

Naphthalimide-based new architecture for fluorescence turn-on sensing of Cu2+ and colorimetric detection of F-/CN.

A new molecular structure 1 has been developed on naphthalimide motif. The amine and triazole binding groups have been employed at the 4-position of naphthalimide to explore the sensing behavior of molecule 1. Single crystal x-ray diffraction and other spectroscopic techniques confirm the identity of 1. Compound 1 exhibits high selectivity and sensitivity for Cu2+ ions in CH3CN. The binding of Cu2+ shows âˆ¼ 70-fold enhancement in emission at 520 nm. The binding follows 1:1 interaction and the detection limit is determined to be 6.49 × 10-7 M. The amine-triazole binding site in 1 also corroborates the detection of F- through a colour change in CH3CN. Initially H-bonding and then deprotonation of amine -NH- in the presence of F- are the sequential steps involved in F- recognition with a detection limit of 4.13 × 10-7 M. Compound 1 is also sensible to CN- like F- ion and they are distinguished by Fe3+ ion. Cu2+-ensemble of 1 fluorimetrically recognizes F- among the tested anions and vice-versa. The collaborative effect of amine and triazole motifs in the binding of both Cu2+ and F-/CN- has been explained by DFT calculation.

Polymeric copper(ii) and dimeric oxovanadium(v) complexes of amide-imine conjugate: bilirubin recognition and green catalysis.

An exceptionally simple amide-imine conjugate, (E)-N'-(4-(diethylamino)-2-hydroxybenzylidene)-4-methylbenzohydrazide (L), derived by the condensation of 4-methyl-benzoic acid hydrazide (PTA) with 4-(diethylamino)-2-hydroxybenzaldehyde was utilized to prepare a dimeric oxo-vanadium (V1) and a one-dimensional (1D) copper(ii) coordination polymer (C1). The structures of L, V1 and C1 were confirmed by single crystal X-ray diffraction analysis. The experimental results indicate that V1 is a promising green catalyst for the oxidation of sulfide, whereas C1 has potential for a C-S cross-coupling reaction in a greener way. Most importantly, C1 is an efficient 'turn-on' fluorescence sensor for bilirubin that functions via a ligand displacement approach. The displacement equilibrium constant is 7.78 × 105 M-1. The detection limit for bilirubin is 1.15 nM in aqueous chloroform (chloroform/water, 1/4, v/v, PBS buffer, and pH 8.0).

Origin of metamagnetism in skyrmion host Cu[Formula: see text]OSeO[Formula: see text].

Skyrmion host chiral Cu[Formula: see text]OSeO[Formula: see text] has attracted researchers due to several intriguing properties. Observation of metamagnetism in low-temperature and low-field makes the magnetic properties of Cu[Formula: see text]OSeO[Formula: see text] more complex. Here, we present an investigation on metamagnetism in Cu[Formula: see text]OSeO[Formula: see text] by analyzing its structural and magnetic properties. Study of magnetic properties reveal spin-flip of one of the Cu[Formula: see text] ions, embedded in square pyramidal CuO[Formula: see text] polyhedra, due to the development of strain in low-temperature and low-field regime. The spin-flip is found to be the main reason for field-induced first-order metamagnetic transition. Magnetic phase diagram of Cu[Formula: see text]OSeO[Formula: see text] has been constructed with the help of magnetization analyses. It is argued that the metamagnetic hysteretic field region may be low-temperature skyrmion phase with additional spiral and tilted-conical phases. A tricritical point has been observed in the phase diagram at which first-order metamagnetic hysteretic field range ceases to exist.

High-Performance MnO2 Nanowire/MoS2 Nanosheet Composite for a Symmetrical Solid-State Supercapacitor.

To improve the production rate of MoS2 nanosheets as an excellent supercapacitor (SC) material and enhance the performance of the MoS2-based solid-state SC, a liquid phase exfoliation method is used to prepare MoS2 nanosheets on a large scale. Then, the MnO2 nanowire sample is synthesized by a one-step hydrothermal method to make a composite with the as-synthesized MoS2 nanosheets to achieve a better performance of the solid-state SC. The interaction between the MoS2 nanosheets and MnO2 nanowires produces a synergistic effect, resulting in a decent energy storage performance. For practical applications, all-solid-state SC devices are fabricated with different molar ratios of MoS2 nanosheets and MnO2 nanowires. From the experimental results, it can be seen that the synthesized nanocomposite with a 1:4 M ratio of MoS2 nanosheets and MnO2 nanowires exhibits a high Brunauer-Emmett-Teller surface area (∼118 m2/g), optimum pore size distribution, a specific capacitance value of 212 F/g at 0.8 A/g, an energy density of 29.5 W h/kg, and a power density of 1316 W/kg. Besides, cyclic charging-discharging and retention tests manifest significant cycling stability with 84.1% capacitive retention after completing 5000 rapid charge-discharge cycles. It is believed that this unique, symmetric, lightweight, solid-state SC device may help accomplish a scalable approach toward powering forthcoming portable energy storage applications.

Different Critical Exponents on Two Sides of a Transition: Observation of Crossover from Ising to Heisenberg Exchange in Skyrmion Host Cu_{2}OSeO_{3}.

We present experimental investigation on critical phenomena in Cu_{2}OSeO_{3} by analyzing the critical behavior of magnetization using a new method. This is necessary as a crossover from 3D Ising to 3D Heisenberg has been observed in Cu_{2}OSeO_{3}. The proposed method is applicable to explore the physics for a wide range of materials showing trivial or nontrivial critical behavior on two sides of the transition. A magnetic phase diagram has been constructed from the critical analysis. Multiple critical points due to multiple phases and transition between them have been observed in the phase diagram of Cu_{2}OSeO_{3}.

Squash cytology of clear cell meningioma: Report of a case.

Clear cell meningioma (CCM) is a rare histological variant of meningioma. It is commonly located at the cerebellopontine angle and the spine particularly around the cauda equina. Squash cytology finding of meningioma is well-established, however there is sparse literature available on squash cytology of CCM. Here we describe a case of CCM occurring in the lumbar spine in a young woman. Initially, on squash cytology a diagnosis of a low grade glioma favouring an ependymoma was considered. Eventually histopathological examination along with immunohistochemistry helped us reach the diagnosis of a CCM. In this article we discuss the cytomorphology of CCM along with its cytological differentials and the hurdles to an accurate diagnosis.

Multiple magnetic phase transitions with different universality classes in bilayer La[Formula: see text]Sr[Formula: see text]Mn[Formula: see text]O[Formula: see text] manganite.

Here, we report three magnetic transitions at 101 K (T[Formula: see text]), 246 K (T[Formula: see text]) and 295 K (T[Formula: see text]) in bilayer La[Formula: see text]Sr[Formula: see text]Mn[Formula: see text]O[Formula: see text]. The second order phase transitions have been identified at these transition points with the help of change in entropy analysis and modified Arrott plots (MAPs). The critical behavior around T[Formula: see text], T[Formula: see text] and T[Formula: see text] have been studied by MAPs and Kouvel-Fisher method. Based on these analyses four magnetic phases are: (1) 2D Ising ferromagnetic (FM) below T[Formula: see text],(2) 2D Heisenberg canted antiferromagnetic (CAFM-I) and FM clusters in temperature range T[Formula: see text] < T < T[Formula: see text], (3) 2D Heisenberg CAFM-II and FM clusters with non magnetically interacting planes in temperature range T[Formula: see text] < T < T[Formula: see text] and (4) paramagnetic for T > T[Formula: see text].

Magnetism in quasi-two-dimensional tri-layer La2.1Sr1.9Mn3O10 manganite.

The tri-layer La[Formula: see text]Sr[Formula: see text]Mn[Formula: see text]O[Formula: see text] manganites of Ruddlesden-Popper (RP) series are naturally arranged layered structure with alternate stacking of ω-MnO[Formula: see text] (ω = 3) planes and rock-salt type block layers (La, Sr)[Formula: see text]O[Formula: see text] along c-axis. The dimensionality of the RP series manganites depends on the number of perovskite layers and significantly affects the magnetic and transport properties of the system. Generally, when a ferromagnetic material undergoes a magnetic phase transition from ferromagnetic to paramagnetic state, the magnetic moment of the system becomes zero above the transition temperature (T[Formula: see text]). However, the tri-layer La[Formula: see text]Sr[Formula: see text]Mn[Formula: see text]O[Formula: see text] shows non-zero magnetic moment above T[Formula: see text] and also another transition at higher temperature T[Formula: see text] 263 K. The non-zero magnetization above T[Formula: see text] emphasizes that the phase transition in tri-layer La[Formula: see text]Sr[Formula: see text]Mn[Formula: see text]O[Formula: see text] not a ferromagnetic to paramagnetic state. We show here the non-zero magnetic moment above T[Formula: see text] is due to the quasi-two-dimensional nature of the tri-layer La[Formula: see text]Sr[Formula: see text]Mn[Formula: see text]O[Formula: see text] manganite. The scaling of the magnetic entropy change confirms the second-order phase transition and the critical behavior of phase transition has been studied around T[Formula: see text] to understand the low dimensional magnetism in tri-layer La[Formula: see text]Sr[Formula: see text]Mn[Formula: see text]O[Formula: see text]. We have obtained the critical exponents for tri-layer La[Formula: see text]Sr[Formula: see text]Mn[Formula: see text]O[Formula: see text], which belong to the short-range two-dimensional (2D)-Ising universality class. The low dimensional magnetism in tri-layer La[Formula: see text]Sr[Formula: see text]Mn[Formula: see text]O[Formula: see text] manganite is also explained with the help of renormalization group theoretical approach for short-range 2D-Ising systems. It has been shown that the layered structure of tri-layer La[Formula: see text]Sr[Formula: see text]Mn[Formula: see text]O[Formula: see text] results in three different types of interactions intra-planer ([Formula: see text]), intra-tri-layer ([Formula: see text]) and inter-tri-layer ([Formula: see text]) such that [Formula: see text] and competition among these give rise to the canted antiferromagnetic spin structure above T[Formula: see text]. Based on the similar magnetic interaction in bi-layer manganite, we propose that the tri-layer La[Formula: see text]Sr[Formula: see text]Mn[Formula: see text]O[Formula: see text] should be able to host the skyrmion below T[Formula: see text] due to its strong anisotropy and layered structure.

Cost effective liquid phase exfoliation of MoS2 nanosheets and photocatalytic activity for wastewater treatment enforced by visible light.

Scalable production of high-quality MoS2 nanosheets remains challenging for industrial applications and research in basic sciences. N-methyl-2pyrrolidine (NMP) is a commonly used solvent for exfoliation of MoS2 nanosheets having further disadvantage of slow volatility rate. The present study demonstrates a cost-effective facile chemical route to synthesize few-layer MoS2 nanosheets using acetone as a solvent and by varying bulk initial concentration of samples to scale up the production in large scale to fulfill the demand for potential applications. In our study, we aim to obtain stable growth of high quality few layer MoS2 nanosheets by long sonication times. Optical absorption spectra, Raman spectra, size of nanosheets and layer thickness of as-grown MoS2 nanosheets were found to be matching with those obtained from other synthesis methods. Effective photocatalytic performance of MoS2 nanosheets without being consumed as a reactant was experimented by decomposing Methylene Blue dye in aqueous solution under irradiation of visible light. This study provides an idea to synthesize low-cost, sustainable and efficient photocatalytic material in large scale for the next generation to control water pollution quite efficiently by protecting the environment from the contamination coming from these dyes.

A polynuclear Cu(ii) complex for real time monitoring of mitochondrial cytochrome C release during cellular apoptosis.

A new amide-imine conjugate, 2-hydroxybenzoic acid-(2-hydroxybenzylidene)-hydrazide (L1), is employed to prepare a single crystal X-ray structurally characterized poly-nuclear Cu(ii) complex (M1). M1 selectively and spatially interacts with cytochrome C (Cyt C) to allow fluorescence imaging of intracellular translocation events in living cells. Thus, direct visualization of a Cyt C translocation event during an apoptotic process is achieved for the first time. The binding constant and LOD are 7.52 × 104 M-1 and 34.0 nM, respectively.

3D-Ising like ferromagnetism in skyrmionic-bubbles host infinite-layer La0.825Sr0.175MnO3 manganite perovskite.

The critical behavior of infinite-layer La0.825Sr0.175MnO3 of Ruddlesden-Popper series manganite has been studied around the transition temperature ([Formula: see text]). To reveal the universality class that explains the critical behavior in La0.825Sr0.175MnO3 several methods, such as modified Arrott plots, Kouvel-Fisher, entropy and critical isotherm analysis have been employed. The critical exponent [Formula: see text] for infinite-layer is obtained independently from critical magnetization isotherm and found to satisfy the Widom scaling relation [Formula: see text]. The universality class of the critical phenomenon in infinite-layer La0.825Sr0.175MnO3 manganite can be explained with the help of renormalization group theory approach for three dimensional (3D) systems. We have shown that a short-range 3D-Ising type interaction is responsible for ferromagnetic and second-order phase transition to paramagnetic phase.

Carrier Induced Hopping to Band Conduction in Pentacene.

Charge transport in organic thin films which are generally polycrystalline is typically limited by the localization of the carriers at lattice defects resulting in low carrier mobilities and carriers move from one state to another state by hopping. However, charge transport in organic semiconductors in their single crystalline phase is coherent due to band conduction and mobilities are not limited by disorder resulting in higher carrier mobility. So it is a challenge to enhance the carrier mobility in a thin film which is the preferred choice for all organic devices. Here, we show that it is possible to increase the carrier mobility in polycrystalline thin films by injecting sufficient carriers such that Fermi level can be moved into the region of high density in Gaussian density of states of molecular solids. When the hopping transport happens through the molecular energy levels whose density is low, mobility is decided by incoherent transport however, when the the hopping transport happens through the energy levels with high density, mobility is decided by coherent transport, as in band conduction. We present results highlighting the observation of both band-like and hopping conduction in polycrystalline organic thin films by varying the concentration of injected charge. More importantly the transition from hopping to band transport is reversible. The observed carrier mobilities in both the regimes match well with theoretical estimates of hopping mobility and band mobility determined from first principles density functional theory.

Ferromagnetism from non-magnetic ions: Ag-doped ZnO.

To develop suitable ferromagnetic oxides with Curie temperature (TC) at or above room temperature for spintronic applications, a great deal of research in doping ZnO with magnetic ions is being carried out over last decade. As the experimental results on magnetic ions doped ZnO are highly confused and controversial, we have investigated ferromagnetism in non-magnetic ion, Ag, doped ZnO. When Ag replaces Zn in ZnO, it adopts 4d9 configuration for Ag2+ which has single unpaired spin and suitable exchange interaction among these spins gives rise to ferromagnetism in ZnO with above room temperature TC. Experimentally, we have observed room temperature ferromagnetism (RTFM) in Ag-doped ZnO with Ag concentration varied from 0.03% to 10.0%. It is shown that zinc vacancy (VZn) enhances the ferromagnetic ordering (FMO) while oxygen vacancy (VO) retards the ferromagnetism in Ag-doped ZnO. Furthermore, the theoretical investigation revealed that VZn along with Ag2+ ions play a pivotal role for RTFM in Ag-doped ZnO. The Ag2+-Ag2+ interaction is ferromagnetic in the same Zn plane whereas anti-ferromagnetic in different Zn planes. The presence of VZn changes the anti-ferromagnetic to ferromagnetic state with a magnetic coupling energy of 37 meV. Finally, it has been established that the overlapping of bound magnetic polarons is responsible for RTFM in low doping concentration. However, anti-ferromagnetic coupling sets in at higher doping concentrations and hence weakens the FMO to a large extent.

Effective Utilization of Waste Red Mud for High Performance Supercapacitor Electrodes.

In recent years, metal oxide-based, inexpensive, stable electrodes are being explored as a potent source of high performance, sustainable supercapacitors. Here, the employment of industrial waste red mud as a pseudocapacitive electrode material is reported. Mechanical milling is used to produce uniform red mud nanoparticles, which are rich in hematite (Fe2O3), and lower amounts of other metal oxides. A comprehensive supercapacitive study of the electrode is presented as a function of ball-milling time up to 15 h. Ten-hour ball-milled samples exhibit the highest pseudocapacitive behavior with a specific capacitance value of ≈317 F g-1, at a scan rate of 10 mV s-1 in 6 m aqueous potassium hydroxide electrolyte solution. The modified electrode shows an extraordinary retention of ≈97% after 5000 cycles. A detailed quantitative electrochemical analysis is carried out to understand the charge storage mechanism at the electrode-electrolyte interface. The formation of uniform nanoparticles and increased electrode stability are correlated with the high performance. This work presents two significant benefits for the environment; in energy storage, it shows the production of a stable and efficient supercapacitor electrode, and in waste management with new applications for the treatment of red mud.

Utility of Squash Cytology in Spinal Lesions with Special Reference to Ki67 Immunostain.

BACKGROUND: Squash cytology is of significant importance in intraoperative consultation of central nervous system (CNS) pathology. There are several studies on squash cytology of CNS lesions, and only a few of them deal with spinal lesions alone. AIMS: (1) To evaluate intraoperative squash cytology of spinal lesions. (2) To correlate cytological diagnosis with histopathological diagnosis and assess the diagnostic accuracy. (3) To study Ki67 expression on squash smears and determine whether it can assist in grading spinal tumours on cytology. MATERIALS AND METHODS: A prospective study was conducted on 68 patients with clinico-radiologically diagnosed lesions of the spine. Intraoperative squash smears were stained with haematoxylin-eosin (H&E) stain, Papanicolaou (Pap) stain, and May-Grünwald-Giemsa (MGG) stain. Subsequently, histological diagnosis was made. Ki67 immunostaining was performed on squash smears and histology sections. RESULTS: The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of squash cytology in spinal lesions were 84.6, 100, 100, 23.1, and 80.88%, respectively. On immunocytochemistry, the mean Ki67 labelling indices for grade I, II, and III tumours were 0, 0.33 and 9%, respectively. CONCLUSION: Squash smear cytology is a rapid intraoperative technique for diagnosing spinal lesions, with high specificity and high positive predictive value. It is more effective in diagnosing neoplasms than non-neoplastic lesions. Ki67 immunostaining can be done on cytology smears to effectively differentiate between WHO grade I and grade II spinal tumours.

Origin of ferromagnetism in Cu-doped ZnO.

It is widely reported during last decade on the observation of room temperature ferromagnetism (RTFM) in doped ZnO and other transition metal oxides. However, the origin of RTFM is not understood and highly debated. While investigating the origin of RTFM, magnetic ion doped oxides should be excluded because it is not yet settled whether RTFM is intrinsic or due to the magnetic ion cluster in ZnO. Hence, it is desirable to investigate the origin of RTFM in non-magnetic ion doped ZnO and Cu-doped ZnO will be most suitable for this purpose. The important features of ferromagnetism observed in doped ZnO are (i) observation of RTFM at a doping concentration much below than the percolation threshold of wurtzite ZnO, (ii) temperature independence of magnetization and (iii) almost anhysteretic magnetization curve. We show that all these features of ferromagnetism in ZnO are due to overlapping of bound magnetic polarons (BMPs) which are created by exchange interaction between the spin of Cu2+ ion and spin of the localized hole due to zinc vacancy [Formula: see text]. Both the experimental and theoretical investigation show that the exchange interaction between Cu2+-Cu2+ ions mediated by [Formula: see text] is responsible for RTFM in Cu-doped ZnO.

Bi-enzyme functionalized electro-chemically reduced transparent graphene oxide platform for triglyceride detection.

Recently, increased attention has been drawn to application of graphene and its derivatives for construction of biosensors, since they can be used to rapidly detect the presence of bio-analytes. Present paper establishes the preparation of a unique transducer which relies on toluidine blue (TB), absorbed by electrochemically reduced graphene oxide (ERGO) transparent thin film onto the surface of the indium tin-oxide (ITO) glass electrode. The proposed TB/ERGO/ITO electrode shows excellent reversible electro-chemical properties. The novel platform has been explored to fabricate a triglyceride (TG) biosensor via co-immobilizing of lipase (LIP) and glycerol dehydrogenase (GDH) onto TB/ERGO/ITO electrode surface. The fabricated bioelectrode (LIP-GDH/TB/ERGO/ITO) directly oxidizes glycerol (produced by catalytic hydrolysis of tributyrin acting as a model TG) in the presence of GDH. The developed bioelectrode replaces unstable biological irreversible redox mediators NAD+/NADH, involved in the triglyceride breakdown reaction. NADH causes fouling on the bioelectrode surface in bi-enzymatic estimation of TG and reduces the shelf-life of biosensor. Electrochemical response studies carried out using cyclic voltammetry reveal that the fabricated electrode can detect tributyrin in the range of 50-400 mg dL-1 with high sensitivity of 29 pA mg-1 dL, low response time of 12 s, long-term stability and a low apparent Michaelis-Menten constant (Kappm) of 0.18 mM, indicating high enzyme affinity of LIP-GDH/TB/ERGO/ITO bioelectrode towards tributyrin. Furthermore, this modified bioelectrode has been explored for estimation of TG with negligible interference in human serum samples. The proposed bi-enzymatic bioelectrode for TG analysis offers an efficient and novel interface for application of graphene and its derivatives in the field of bioelectronic devices.