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CDKL5 deficiency disorder (CDD) is a rare, X-linked, developmental and epileptic encephalopathy characterised by severe global developmental impairment and seizures that can begin in the first few months after birth and are often treatment refractory. Ganaxolone, an investigational neuroactive steroid, reduced seizure frequency in an open-label, phase 2 trial that included patients with CDD. We aimed to further assess the efficacy and safety of ganaxolone in patients with CDD-associated refractory epilepsy.In the double-blind phase of this randomised, placebo-controlled, phase 3 trial, done at 39 outpatient clinics in eight countries (Australia, France, Israel, Italy, Poland, Russia, the UK, and the USA), patients were eligible if they were aged 2-21 years with a pathogenic or probably pathogenic CDKL5 variant and at least 16 major motor seizures (defined as bilateral tonic, generalised tonic-clonic, bilateral clonic, atonic, or focal to bilateral tonic-clonic) per 28 days in each 4-week period of an 8-week historical period. After a 6-week prospective baseline period, patients were randomly assigned (1:1) via an interactive web response system to receive either enteral adjunctive ganaxolone or matching enteral adjunctive placebo (maximum dose 63 mg/kg per day for patients weighing ≤28 kg or 1800 mg/day for patients weighing28 kg) for 17 weeks. Patients, caregivers, investigators (including those analysing data), trial staff, and the sponsor (other than the investigational product manager) were masked to treatment allocation. The primary efficacy endpoint was percentage change in median 28-day major motor seizure frequency from the baseline period to the 17-week double-blind phase and was analysed (using a Wilcoxon-rank sum test) in all patients who received at least one dose of trial treatment and for whom baseline data were available. Safety (compared descriptively across groups) was analysed in all patients who received at least one dose of trial treatment. This study is registered with ClinicalTrials.gov, NCT03572933, and the open-label extension phase is ongoing.Between June 25, 2018, and July 2, 2020, 114 patients were screened for eligibility, of whom 101 (median age 6 years [IQR 3 to 10]) were randomly assigned to receive either ganaxolone (n=50) or placebo (n=51). All patients received at least one dose of a study drug, but seizure frequency for one patient in the ganaxolone group was not recorded at baseline and so the primary endpoint was analysed in a population of 100 patients. There was a median percentage change in 28-day major motor seizure frequency of -30·7% (IQR -49·5 to -1·9) in the ganaxolone group and of -6·9% (-24·1 to 39·7) in the placebo group (p=0·0036). The Hodges-Lehmann estimate of median difference in responses to ganaxolone versus placebo was -27·1% (95% CI -47·9 to - 9·6). Treatment-emergent adverse events occurred in 43 (86%) of 50 patients in the ganaxolone group and in 45 (88%) of 51 patients in the placebo group. Somnolence, pyrexia, and upper respiratory tract infections occurred in at least 10% of patients in the ganaxolone group and more frequently than in the placebo group. Serious adverse events occurred in six (12%) patients in the ganaxolone group and in five (10%) patients in the placebo group. Two (4%) patients in the ganaxolone group and four (8%) patients in the placebo group discontinued the trial. There were no deaths in the double-blind phase.Ganaxolone significantly reduced the frequency of CDD-associated seizures compared with placebo and was generally well tolerated. Results from what is, to our knowledge, the first controlled trial in CDD suggest a potential treatment benefit for ganaxolone. Long-term treatment is being assessed in the ongoing open-label extension phase of this trial.Marinus Pharmaceuticals.

A relatively recent method called the Hermite Wavelet Method (HWM) is used to design a simple strategy for solving the Fokker-Planck equation (FPE) for a given pair of drift and diffusion functions in stochastic phenomena. The Fokker-Plank equation is analyzed for Morse, Hulthen and logarithmic potentials. The joint and marginal probability density functions of FPE are obtained. The strategy is efficient to apply to many linear and nonlinear problems and can significantly reduce computing labour. To demonstrate the applicability and effectiveness of the approach and to obtain the probability distribution functions of FPE, illustrative examples are provided. Mathematical subject classification: 35K20

Variable energy positron beam with Doppler broadening spectroscopy (DBS) was used to investigate the depth-resolved defects formed by two fluencies of 130 keV N+ implanted in Semi Insulating (SI) 6H-SiC. The implanted ions induced damages near the surface and to a depth of 300 nm as simulated by SRIM analysis. Defects recovery, accumulation, and its behavior with two annealing temperatures were also considered. Defect types and its effect on annealing were analyzed from the changes in electron momentum and modeled as layers using variable energy positron fitting (VEPFIT) methods. Inclusion of electric field strength in the fitting procedure supported layer characteristics and the state of charge carriers. Di-vacancies, vacancy complexes observed in the damaged layers were agglomerated at the surface and tend to cure on annealing.

A cylindrical latent heat thermal storage system having a phase change material, HS89, encased in spherical capsules and stacked in rows to form a packed bed phase change material containment was considered for the experimental investigation. The heat is stored at 89 °C which is very useful for many process industry applications using solar water heaters. Three different aspect ratios were considered for experimentation. The temperature profiles of the phase change material containment and the heat transfer fluid at various heights were measured and monitored continuously. These temperature values were used to determine the variation in charging efficiency, stratification number and Richardson number of the storage system which are very useful parameters to design a storage system. The results presented in this paper will be very useful to design a phase change material based thermal storage for solar thermal applications.

Nanofluids are an emerging technology in heat transfer field. Nanofluids can be used in a variety of industrial applications because of improved thermo-physical properties. In this field, the nano sized materials are suspended with the base fluid. This nanoparticles suspended base fluid enhances heat transfer properties such as thermal conductivity, dynamic viscosity and density. Thus, the enhanced properties of base fluid may enhance the efficiency of diffuser heat exchanger. This will lead to the increase in testing time of the engine. In this study a methodology to estimate the thermal properties of nanofluids is discussed.

The nano garnet particle is dispersed into SN500 grade lubricating oil through Digital probe sonicator for formulating garnet nanofluids. The temperature and particle concentration dependent density and heat dissipation rate are experimentally investigated. The results show that the density of base fluid increases with the addition of nanoparticles. Also, the homogeneous dispersion of garnet nanoparticles into the base fluid has the considerable effect on the nanoparticle concentration and temperature dependent thermal energy dissipation capability.

A series of relatively small studies collectively suggest that zonisamide may be effective in the treatment of infantile spasms. Using a large single‐center cohort of children with infantile spasms, we set out to evaluate the efficacy and safety of zonisamide. We retrospectively identified all patients with infantile spasms who were treated with zonisamide at our center. For each patient, we recorded dates of birth, infantile spasms onset, response (if any), and most recent follow‐up. To quantify zonisamide exposure, we recorded daily dosage and patient weight at each sequential encounter so as to allow calculation of peak and weighted‐average weight‐based dosage. We identified 87 children who were treated with zonisamide, of whom 78 had previously been treated with hormonal therapy or vigabatrin. Peak and weighted‐average zonisamide dosage were 7.1 (interquartile range 3.6, 10.2) and 5.4 (interquartile range 3.0, 8.9) mg/kg/day, respectively. Whereas five (6%) patients exhibited resolution of epileptic spasms, only two (2%) patients exhibited video‐EEG confirmed resolution of both epileptic spasms and hypsarrhythmia (electroclinical response). Importantly, both electroclinical responders had not previously been treated with hormonal therapy or vigabatrin; in contrast, none of the 78 children with prior failure of hormonal therapy or vigabatrin subsequently responded to zonisamide. Zonisamide was well tolerated, and there were no deaths. This study suggests that zonisamide exhibits favorable tolerability but very limited efficacy among patients who do not respond to first‐line therapy.

To investigate spatial correlation between interictal HFOs and neuroimaging abnormalities, and to determine if complete removal of prospectively identified interictal HFOs correlates with post-surgical seizure-freedom.Interictal fast ripples (FRs: 250-500 Hz) in 19 consecutive children with pharmacoresistant focal epilepsy who underwent extra-operative electrocorticography (ECoG) recording were prospectively analyzed. The interictal FRs were sampled at 2000 Hz and were visually identified during 10 min of slow wave sleep. Interictal FRs, MRI and FDG-PET were delineated on patient-specific reconstructed three-dimensional brain MRI.Interictal FRs were observed in all patients except one. Thirteen out of 18 patients (72%) exhibited FRs beyond the extent of neuroimaging abnormalities. Fifteen of 19 children underwent resective surgery, and survival analysis with log-rank test demonstrated that complete resection of cortical sites showing interictal FRs correlated with longer post-operative seizure-freedom (p 0.01). Complete resection of seizure onset zones (SOZ) also correlated with longer post-operative seizure-freedom (p = 0.01), yet complete resection of neuroimaging abnormalities did not (p = 0.43).Prospective visual analysis of interictal FRs was feasible, and it seemed to accurately localize epileptogenic zones.Topological extent of epileptogenic region may exceed what is discernible by multimodal neuroimaging.

Implementation of a state of the art data acquisition and analysis program for variable low energy positron beam using LabVIEW based automation software is described. The program does the following functions: (a) controlling the remote programmable high voltage–power supply to bias the sample negatively (i.e., to vary the positron beam energy), (b) control of Windows based PCI MCA card, (c) calculating the S, W, R and ortho-positronium self-annihilation fraction (fPs) parameters, errors, and other relevant parameters, (d) saving the raw spectra, results and log data file and (e) dynamic display of raw spectrum and S, W, fPs versus energy for easy visualization of progress of the experiment. The USB based interfacing standard of this design provides easy connectivity to the personal computers.

A signal tapping circuit has been designed to derive the fast timing signal from the Chevron type, 2 stage MCP having phosphor screen as a readout device. Using this, the timing property of the MCP-BaF2 system has been studied using the digital storage oscilloscope in which a timing resolution of ~ 500 ps has been obtained. The applicability of MCP with phosphor screen configuration for timing measurements has been demonstrated.

The study is intended to investigate the low energy nitrogen ion implantation induced behavior and re-crystallization in semi-insulating 6H-SiC from surface to 5 µm, by Raman spectroscopy. The nature of defects accumulation related to the SiC bond breakages and re-crystallization on vacuum annealing were analyzed from the A1(LO) phonon mode and probed at successive depth from the surface. Variations on the asymmetrical A1(LO) peaks of as-implanted samples were made to order upon annealing, and the mode regained. The peak intensity variation of A1(LO) mode indicated the disorder accumulation. The identified damage depth was in good agreement with Stopping and Ranges of Ions in Matter (SRIM). The changes in Si-Si, deformed-Si-C, C-C vibrations and crystalline-SiC were used to explain the defect role in the implanted and annealed samples.

Positron beam measurements carried out on high temperature Ni+ implanted FeCrCoNi show no void formation but only presence of monovacancies. With thermal treatment, evidence for the formation of nano sized σ-CoCr are obtained from positron based ratio curve analysis in the temperature range 973–1123 K. Corroborative evidence for the presence of these precipitates are obtained from EBSD and GIXRD measurements. Further annealing beyond 1150 K leads to coarsening of these precipitates and they no longer trap the positrons.

The formation of hydrogen and helium associated defect complexes and their influence on the nucleation and growth of helium bubbles in Indian Reduced Activation Ferritic/Martensitic steel have been investigated using positron annihilation spectroscopy. Isochronal annealing study has been performed on the samples individually irradiated with H and He ions, and sequentially irradiated with both H and He ions. All the as-irradiated samples show higher S-parameter as compared to the unirradiated sample due to the presence of irradiation-induced vacancy-type defects. Among the single ion irradiated samples, hydrogen irradiated sample shows the presence of H-vacancy complexes having high hydrogen content in the as-irradiated state, an increase in S-parameter due to the release of hydrogen from these complexes at 373 K, and complete defect recovery after annealing at 673 K. The helium irradiated sample shows three distinct stages of annealing; a defect annealing stage with decrease in S-parameter from as-irradiated to 573 K, bubble nucleation stage with a stable S-parameter from 573 to 673 K and the bubble growth region characterized by an increase in S-parameter is observed from 673 to 973 K. Among the sequential irradiated samples, the sample irradiated with helium first and then with hydrogen shows a reduced S-parameter which is due to the saturation of helium-induced vacancies by hydrogen or the formation of H-He-vacancy complexes. Both the sequential irradiated samples show a reduced S-parameter from 573 to 673 K due to the formation of H-He-vacancy complexes under post-irradiation annealing. The nucleation and growth stage of helium bubbles observed under isochronal annealing is independent of the sequence of irradiation. Both the sequential irradiated samples show the bubble nucleation and growth stage similar to helium irradiated sample and further, the presence of hydrogen has no noticeable role in this stage.

Objective Delta-gamma phase-amplitude coupling in EEG is useful for localizing epileptic sources and evaluate severity in children with infantile spasms. We (1) develop an automated EEG preprocessing pipeline to clean data using artifact subspace reconstruction (ASR) and independent component (IC) analysis (ICA) and (2) evaluate delta-gamma modulation index (MI) as a method to distinguish children with epileptic spasms (cases) from normal controls during sleep and awake. Methods Using 400 scalp EEG datasets (200 sleep, 200 awake) from 100 subjects, we calculated MI after applying high-pass and line-noise filters (Clean 0), and after ASR followed by either conservative (Clean 1) or stringent (Clean 2) artifactual IC rejection. Classification of cases and controls using MI was evaluated with Receiver Operating Characteristics (ROC) to obtain area under curve (AUC). Results The artifact rejection algorithm reduced raw signal variance by 29-45% and 38-60% for Clean 1 and Clean 2, respectively. MI derived from sleep data, with or without preprocessing, robustly classified the groups (all AUC > 0.98). In contrast, group classification using MI derived from awake data was successful only after Clean 2 (AUC = 0.85). Conclusions We have developed an automated EEG preprocessing pipeline to perform artifact rejection and quantify delta-gamma modulation index.

In recent times, Social Networks became ubiquitous in our daily life. These networks can be used to obtain high-volume data related to any given event or topic. Twitter, one of the famous networks, became the wealthy supply of discussed topics. The users on Twitter express their point of views or opinions by tweets concerning different topics in a variety of fields. The data generated on Twitter can be extracted via Sentiment Analysis. In this proposed system, an artificial intelligence concept (NLP) is applied that understands the sentiment of extracted data and polarizes them into positive, negative, or neutral. These polarized data are then grouped based on their similarities and differences through a grouping algorithm. The data obtained is then represented graphically in form of a bar-chart. The information obtained from this text, an analysis based on emotions is used to create daily trends related to the event which is used to identify emerging patterns of this data or the current user sentiments related to the given event or topic

OBJECTIVE Favorable neurodevelopmental outcomes in epileptic spasms (ES) are tied to early diagnosis and prompt treatment, but uncertainty in the identification of the disease can delay this process. Therefore, we investigated five categories of computational electroencephalographic (EEG) measures as markers of ES. METHODS We measured 1) amplitude, 2) power spectra, 3) Shannon entropy and permutation entropy, 4) long-range temporal correlations, via detrended fluctuation analysis (DFA) and 5) functional connectivity using cross-correlation and phase lag index (PLI). EEG data were analyzed from ES patients (n = 40 patients) and healthy controls (n = 20 subjects), with multiple blinded measurements during wakefulness and sleep for each patient. RESULTS In ES patients, EEG amplitude was significantly higher in all electrodes when compared to controls. Shannon and permutation entropy were lower in ES patients than control subjects. The DFA intercept values in ES patients were significantly higher than control subjects, while DFA exponent values were not significantly different between the groups. EEG functional connectivity networks in ES patients were significantly stronger than controls when based on both cross-correlation and PLI. Significance for all statistical tests was p < 0.05, adjusted for multiple comparisons using the Benjamini-Hochberg procedure as appropriate. Finally, using logistic regression, a multi-attribute classifier was derived that accurately distinguished cases from controls (area under curve of 0.96). CONCLUSIONS Computational EEG features successfully distinguish ES patients from controls in a large, blinded study. SIGNIFICANCE These objective EEG markers, in combination with other clinical factors, may speed the diagnosis and treatment of the disease, thereby improving long-term outcomes.

ObjectiveFavorable neurodevelopmental outcomes in epileptic spasms (ES) are tied to early diagnosis and prompt treatment, but uncertainty in the identification of the disease can delay this process. Therefore, we investigated five computational electroencephalographic (EEG) measures as markers of ES.MethodsWe measured 1) amplitude, 2) power spectra, 3) entropy, 4) long-range temporal correlations, via detrended fluctuation analysis (DFA) and 5) functional connectivity of EEG data from ES patients (n=40 patients) and healthy controls (n=20 subjects), with multiple blinded measurements during wakefulness and sleep for each patient.ResultsIn ES patients, EEG amplitude was significantly higher in all electrodes. Shannon and permutation entropy were lower in ES patients than control subjects, while DFA intercept values in ES patients were significantly higher than control subjects. DFA exponent values were not significantly different between the groups. EEG functional connectivity networks in ES patients were significantly stronger than controls. Using logistic regression, a multi-attribute classifier was derived that accurately distinguished cases from controls (area under curve of 0.96).ConclusionsComputational EEG features successfully distinguish ES patients from controls in a large, blinded study.SignificanceThese objective EEG markers, in combination with other clinical factors, may speed the diagnosis and treatment of the disease, thereby improving long-term outcomes.HighlightsObjective computational EEG features may aid diagnosis of epileptic spasms (ES)ES EEG has increased delta and theta power and decreased entropy relative to controlsStronger functional connectivity networks differentiate ES patients from controls

Purpose Epileptic spasms are often preceded by focal (or multifocal) seizures. Based on a series of case reports suggesting that carbamazepine and oxcarbazepine may induce epileptic spasms, we set out to rigorously evaluate the potential association between exposure to voltage-gated sodium channel blockade and latency to epileptic spasms. Methods We identified 50 cases (children with focal seizures and evolution to epileptic spasms) and 50 controls (children with focal seizures without evolution to epileptic spasms). For each patient, we reviewed all sequential neurology encounters between onset of epilepsy and emergence of epileptic spasms. For each encounter we recorded seizure-frequency and all anti-seizure therapy exposures. Using multivariable Cox proportional hazards regression, we evaluated the association between voltage-gated sodium channel exposure (carbamazepine, oxcarbazepine, lacosamide, or phenytoin) and latency to epileptic spasms onset, with adjustment for etiology and seizure-frequency. Results Latency to epileptic spasms onset was independently associated with exposure to sodium channel blockade (hazard ratio = 2.4; 95% CI 1.1–5.2; P = 0.03) and high-risk etiology (hazard ratio = 2.8; 95% CI 1.5–5.1; P = 0.001). With assessment for interaction between sodium channel blockade and etiology, we identified an estimated 7-fold increased risk of epileptic spasms with the combination of sodium channel blockade and high-risk etiology (hazard ratio = 7.0, 95% CI 2.5–19.8; P Conclusion This study suggests that voltage-gated sodium channel blockade may induce epileptic spasms among children at risk on the basis of etiology. Further study is warranted to replicate these findings, ascertain possible drug- and dose-specific risks, and identify potential mechanisms of harm.

An experimental study has been established to understand the effective cylinder wall heat transfer rate and temperature of a direct injection diesel engine. Temperatures were calculated under a wide range of load at different locations in the cylinder block and cylinder head of the engine using pre-arranged thermocouples to acquire the temperature gradient and consequently realize the equivalent heat transfer rate, cylinder wall temperatures, heat transfer co-efficient and engine speed. Diesel and biodiesel blends (B20 and B100) are used as fuels and the temperature readings are found using a ‘k-type’ thermocouple and temperature readings are noted. Raise in the cylinder temperature is observed as the engine torque increases for the diesel and biodiesel. As the engine speed increases, the exhaust gas velocity involved in and out of the engine will increases and this lead to an increase in the heat transfer co-efficient for diesel and biodiesel.

Businesses running software applications are moving more towards vendor-agnostic approaches. Integration testing becoming more demanding and complex than ever. Determining integration testing requires a solid dependency pattern among different software applications. We would like to use here an NLP (Natural language processing) & Machine learning Classification model-based approach to identify the dependency graph between different component across applications. There are existing approaches eliciting about package dependencies and source code-based dependencies. In this paper, we would like to introduce an approach to understand the communication dependencies between products rather than just high-level package or install dependencies. The communication dependencies will be prioritized based on the frequency and criticality of usage. The prioritization helps us in determining the software inter-dependency patterns for Integration testing.

Preparation of superconducting thin films of the Cu-doped Ruthenocuprate superconductor GdSr2Ru0.9Cu2.1O8 has been attempted by pulsed laser deposition method. Thin films were deposited on different substrates employing different laser ablation parameters with the idea of obtaining good-quality films which exhibit superconductivity. The crystal structure and morphology of the thin films were characterized by X-ray diffraction and scanning electron microscopy measurements and optical characteristics by Raman scattering measurements. High-temperature ex situ oxygen annealing led to the formation of homogeneous films with the occurrence of an onset of superconductivity, traced by electrical resistivity measurements. Increasing the annealing time has led to a systematic improvement in the sample quality and the physical properties. However, prolonged high-temperature annealing seems to cause deterioration in properties as seen from electrical resistivity and Raman scattering measurements. The studies reveal the importance of an optimal high-temperature oxygen annealing procedure to induce superconductivity in thin films of this Ruthenocuprate system.

Positron beam-based Doppler broadening results on He ion-implanted FeCrCoNi show distinct changes in defect-sensitive S-parameter corresponding to the formation of helium-vacancy complexes, nucleation/ growth of helium bubbles, and finally the helium bubble rupture, with isochronal annealing. Data analyses of the positron beam-based ratio curves provide clear information on the kinetics of bubble growth and rupture. The difference data in S-parameter (ΔS), which corresponds to the bubble growth, displays a maximum at 1123 K, with annealing temperature. Comparing the ΔS value to that reported for nickel, it is concluded that FeCrCoNi has higher bubble growth resistance than nickel.

Indian reduced activation ferritic-martensitic steel was irradiated with 1.1 MeV Fe ions to various doses from 1 to100 dpa at room temperature. The depth profiling of irradiation-induced vacancy-ty...

Fly ash is used in concrete industry to reduce the amount of cement and to enhance the durability of concrete. Nuclear industry recently adopted fly ash concrete as a government initiative to reduce carbon footprint and also to provide an impermeable skin for the several structures in the cooling water system exposed to marine environment for enhanced durability. Earlier detailed studies on fly ash concrete has shown that despite its superiority over conventional concrete with respect to strength and durability, some concerns such as delayed setting and hydration, low early-age strength, and higher carbonation may pose a problem for its wider application. The present work is an attempt to overcome these deficiencies by nanophase modification of concrete with the incorporation of nano-titania and nano-calcium carbonate at 2% by weight of cement. Four different types of concrete mix were arrived and specimens of different sizes were cast in order to explore the various properties of concrete. After 28 days of curing in potable water, the samples were exposed to seawater at Nuclear Desalination Demonstration Plant (NDDP) sump at Kalpakkam and were withdrawn for testing at different ages like 56, 90, 180 and 365 days. Nanophase modification increased the pozzolanic activity resulting in faster hydration, early-age strength and long-term compressive and split tensile strength, permissible electrical resistivity for corrosion, lower chloride ion penetration, carbonation depth biofilm formation and higher internal pH. Among the different mixes, the synergy of 1% NC and 1% NT emerged superior with excellent concrete properties related to mechanical properties, pore structure, durability and optimum antibacterial activity.

Owing to the attractive front-end styling and restricted available space in the automotive underhood zone, both upstream and downstream directions of heat exchangers are subjected to obstructions in the cooling airflow path. These obstructions disturb the airflow distribution and influence the thermal performance of the heat exchanger. As obstructions are inevitable in the cooling airflow path, a new approach must be developed to study and control the influence of obstructions on the heat exchanger performance. In this paper, a new methodology is proposed to predict the heat transfer performance of automotive radiator for practical range of blockage areas. The air velocity distribution over the heat exchanger face is investigated using a computational fluid dynamics tool under an obstructed airflow path. The thermal performance of the heat exchanger is evaluated with the existing correlation. The obtained results are validated with experimental results. Further, the consideration of obstructions/blockage in the cooling airflow path, along with an existing radiator performance testing study (IS 13687:1993), can provide better input to the front-end design of vehicles.

Electrochemical measurements combined with high resolution transmission electron microscopy studies have been used to follow the microstructure changes in nanoporous Au subjected to electro-oxidation and oxygen reduction reactions. The microscopy results reveal that different types of lattice defects such as stacking fault tetrahedra present in as-dealloyed and oxide formed nanoporous Au. It is shown that Au inter-planar spacing in the defect concentrated regions in as-dealloyed nanoporous Au has increased by 8%. This anomalous change may be attributed to the binding of oxygen containing ads-species in the electrolyte on Au atoms, albeit weakly, in the presence of defects.

The molecular structure of 2,4−dinitroanisole (DNAN) is optimized using Gaussian 09W program, two stable molecular structures with different methoxy group orientations are obtained and vibrational frequencies are calculated for the two optimized molecular structures. DNAN crystal structure is optimized using CASTEP and VASP codes and phonon frequencies are calculated and assigned. Computed frequencies compare well with experimental values. Pressure dependent phase transformation in DNAN is investigated by Raman spectroscopy and X-ray diffraction. Differences between the Raman spectra of DNAN and trinitrotoluene (TNT) point to a larger phonon energy gap in DNAN to be a possible reason for the lower impact sensitivity of DNAN. Appearance of new Raman bands and discontinuity of the bands above 1.3 GPa indicates a phase transformation. Changes in the X-ray diffraction patterns confirm the phase transformation. The transformation of the ambient monoclinic to an orthorhombic structure starts at around 2 GPa. At 6.8 GPa the monoclinic structure completely transforms into orthorhombic with a volume collapse of 10%. Bulk moduli for the monoclinic and orthorhombic phases are estimated as ∼12 GPa and 27 GPa respectively, pointing to a lower impact sensitivity of the orthorhombic phase.

Diisopropylammonium salts have drawn attention in recent years due to their room temperature ferroelectric properties. Triclinic diisopropylammonium perchlorate (DIPAP) exhibits ferroelectricity at room temperature. We have carried out density functional theory calculations to assign the phonon modes in DIPAP. High pressure Raman spectra of DIPAP were recorded up to ~3 GPa. Discontinuity in the NH2 bending and stretching mode frequencies and appearance of new bands at 0.7 GPa suggests a phase transition by a rearrangement in hydrogen network. Broadening of lattice modes at 1.3 -1.7 GPa indicates loss of crystalline nature above 1.7 GPa. High pressure synchrotron x-ray diffraction of DIPAP shows an isostructural phase transition at 0.6 GPa and confirms amorphization at 1.5 GPa that may lead to loss of ferroelectricity above this pressure. The ambient phase is reversible after releasing pressure. Bulk modulus of DIPAP was determined to be 16.7 GPa.

Single crystal samples of NbAs2 semimetal have been synthesized and characterized by Raman spectroscopy. Magneto-transport experiments have been carried out in a temperature range of 2.5 K to 300 K under a magnetic field between 0 T and 14 T. The metallic temperature variation of resistivity without a magnetic field exhibits a huge magneto- resistance ∼105 % with 14 T at the lowest measured temperature. The non-linear Hall resistance evinces the role of multiple carriers in the transport and the positive Hall coefficient indicates a hole dominant system. Strongly temperature dependent carrier mobility below 75 K attains ultra-high values at low temperatures. Magnetization measurements display de Haas van Alphen oscillations that is anisotropic with respect to the crystal axes. Cyclotron mass and Dingle temperature have been estimated from the amplitude variation of oscillation in a varying field. The studies show that the low carrier mass and the resulting high mobility is the reason for the large magneto-resistance in NbAs2.