Probing the solute-drag effect and its role in stabilizing the orthorhombic phase in bulk La-doped HfO2 by X-ray and gamma ray spectroscopy

The recent observation of ferroelectricity in ultra thin films of hafnium oxide (HfO2) has been attributed to the orthorhombic (o) phase of HfO2 with space group Pca21. Although this oxide is polymorphic in nature, this polar o-phase is known to be stabilized in the doped thin film oxide. The objective of the present experiment is to stabilize the o-phases in La doped bulk polycrystalline HfO2 and investigate their evolution with the doping concentration through Time Differential Perturbed Angular Correlation (TDPAC), X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) measurements. The present work reports the presence of both the polar Pca21 phase and the antipolar Pbca phase at different La-concentrations. Two o-phases of HfO2 with space groups Pca21 and Pbca, difficult to distinguish by other complimentary methods, could be unambiguously identified by utilizing the atomic scale sensitivity of the electric field gradient (EFG) embedded in TDPAC spectroscopy. The determination of the oxidation state and the local environment of La-atoms by XANES and EXAFS measurements illuminates the microscopic role of the dopant in stabilizing the o-phase. The "solute drag model" proposes a critical crystallite size for the nucleation of the o-phase in bulk HfO2 and explains the role of the La-dopant in stabilizing the o-phase. Thus the present study shows the possibility of stabilizing the polar o-phase and hence attaining ferroelectricity in bulk HfO2 to augment the scope of future application for this ferroelectric device.

Hunting down the X17 boson at the CERN SPS

Recently, the ATOMKI experiment has reported new evidence for the excess of e + e - events with a mass ∼ 17 MeV in the nuclear transitions of 4 He, that they previously observed in measurements with 8 Be. These observations could be explained by the existence of a new vector X 17 boson. So far, the search for the decay X 17 → e + e - with the NA64 experiment at the CERN SPS gave negative results. Here, we present a new technique that could be implemented in NA64 aiming to improve the sensitivity and to cover the remaining X 17 parameter space. If a signal-like event is detected, an unambiguous observation is achieved by reconstructing the invariant mass of the X 17 decay with the proposed method. To reach this goal an optimization of the X 17 production target, as well as an efficient and accurate reconstruction of two close decay tracks, is required. A dedicated analysis of the available experimental data making use of the trackers information is presented. This method provides independent confirmation of the NA64 published results [1], validating the tracking procedure. The detailed Monte Carlo study of the proposed setup and the background estimate show that the goal of the proposed search is feasible.

Measurement of the Low-Energy Antideuteron Inelastic Cross Section

In this Letter, we report the first measurement of the inelastic cross section for antideuteron-nucleus interactions at low particle momenta, covering a range of 0.3≤p<4  GeV/c. The measurement is carried out using p-Pb collisions at a center-of-mass energy per nucleon-nucleon pair of sqrt[s_{NN}]=5.02  TeV, recorded with the ALICE detector at the CERN LHC and utilizing the detector material as an absorber for antideuterons and antiprotons. The extracted raw primary antiparticle-to-particle ratios are compared to the results from detailed ALICE simulations based on the geant4 toolkit for the propagation of (anti)particles through the detector material. The analysis of the raw primary (anti)proton spectra serves as a benchmark for this study, since their hadronic interaction cross sections are well constrained experimentally. The first measurement of the inelastic cross section for antideuteron-nucleus interactions averaged over the ALICE detector material with atomic mass numbers ⟨A⟩=17.4 and 31.8 is obtained. The measured inelastic cross section points to a possible excess with respect to the Glauber model parametrization used in geant4 in the lowest momentum interval of 0.3≤p<0.47  GeV/c up to a factor 2.1. This result is relevant for the understanding of antimatter propagation and the contributions to antinuclei production from cosmic ray interactions within the interstellar medium. In addition, the momentum range covered by this measurement is of particular importance to evaluate signal predictions for indirect dark-matter searches.

Search for Axionlike and Scalar Particles with the NA64 Experiment

We carried out a model-independent search for light scalar (s) and pseudoscalar axionlike (a) particles that couple to two photons by using the high-energy CERN SPS H4 electron beam. The new particles, if they exist, could be produced through the Primakoff effect in interactions of hard bremsstrahlung photons generated by 100 GeV electrons in the NA64 active dump with virtual photons provided by the nuclei of the dump. The a(s) would penetrate the downstream HCAL module, serving as a shield, and would be observed either through their a(s)→γγ decay in the rest of the HCAL detector, or as events with a large missing energy if the a(s) decays downstream of the HCAL. This method allows for the probing of the a(s) parameter space, including those from generic axion models, inaccessible to previous experiments. No evidence of such processes has been found from the analysis of the data corresponding to 2.84×10^{11} electrons on target, allowing us to set new limits on the a(s)γγ-coupling strength for a(s) masses below 55 MeV.

Studies on volatilization behavior of RuO4 from nitric acid medium

This paper reports volatilization behavior of RuO4 from nitric acid medium using UV–Vis spectroscopy. Ruthenium (III) solution was oxidized to Ru (VIII) using potassium metaperiodate. The absorption peak of RuO4 at 385 nm was used to measure Ru(VIII) concentration in solution. The volatilization kinetics has been studied at different temperature and used to derive rate constant and activation energy values. Almost 82% Ruthenium (VIII) has been volatilized from nitric acid medium at 70 °C whereas it is only 15% at 25 °C. Effect of different parameters like temperature, potassium metaperiodate concentration and nitric acid concentration on volatilization has been studied in depth and reported in this paper.

0669 The Effects Of Continuous Positive Airway Pressure Therapy In Moderate To Severe Obstructive Sleep Apnea: A High-density EEG Study

Introduction

A previous high-density electroencephalography (EEG) investigation in asymptomatic OSA showed regional deficits in sleep EEG power particularly slow wave activity (SWA) during NREM sleep in the parietal region. It is unclear whether treatment with CPAP can reverse local sleep EEG abnormalities in OSA, and whether any recovery is related to improvement in sleep-dependent memory consolidation.

Methods

Fifteen male participants (age 50.4±6.5yrs, AHI 51.7±23.5/h) with moderate-severe OSA (AHI&gt;15/h) underwent overnight polysomnography with 256-channel high-density EEG at baseline and following 3 months of CPAP therapy. A word paired associates declarative memory task was administered before and after sleep. After artefact removal, spectral analysis was performed for all channels. Topographical power maps were calculated for standard frequency ranges for NREM sleep (164 channels within a 0.57 radius from the vertex). Maps were compared using both absolute and normalized power (z-scores computed for each subject) and differences between baseline and treatment were determined by statistical nonparametric mapping.

Results

In 11 CPAP compliant patients (intolerant of CPAP [n=3]/high-density EEG [n=1]), analysis of polysomnographic variables showed that total sleep time did not differ but N1 (baseline vs. treatment: 66.9 vs. 39.5 mins,p=0.008) and N2 (195.0 vs. 150.6 mins,p=0.002) sleep was lower and N3 (89.8 vs. 128.7 mins,p=0.003) was higher after CPAP. Topographic analysis of high-density EEG data revealed a regional increase in SWA (1-4.5Hz) EEG power during N3 sleep in a cluster of electrodes overlying the centro-parietal cortex (cluster mean t-value=2.87,p=0.02). The change in overnight declarative memory consolidation (% recognition) after CPAP was significantly correlated with the change in slow spindle frequency activity in frontal regions (cluster mean r=0.875,p=0.003).

Conclusion

CPAP treatment may enhance localised deficits in sleep EEG activity in OSA, and specific regional recovery may translate to memory improvements in the short-term. These data also highlight the potential for long-term therapeutic effects on cognitive outcomes in OSA.

Support

 

Exploring functionalized titania for task specific application of efficient separation of trivalent f-block elements

Functionalized titania, obtained by grafting the dipicolinic acid functionality, was explored for task specific application of highly efficient separation of trivalent f-block elements.

Use of transient elastography in detection of liver fibrosis in psoriasis patients – A cross- sectional study

Background and Aims:

Methods:

Results:

Limitations:

Conclusion:

Dark Matter Search in Missing Energy Events with NA64

A search for sub-GeV dark matter production mediated by a new vector boson A^{'}, called a dark photon, is performed by the NA64 experiment in missing energy events from 100 GeV electron interactions in an active beam dump at the CERN SPS. From the analysis of the data collected in the years 2016, 2017, and 2018 with 2.84×10^{11} electrons on target no evidence of such a process has been found. The most stringent constraints on the A^{'} mixing strength with photons and the parameter space for the scalar and fermionic dark matter in the mass range ≲0.2  GeV are derived, thus demonstrating the power of the active beam dump approach for the dark matter search.

Preparation of chitosan functionalized polyamidoamine for the separation of trivalent lanthanides from acidic waste solution

The manuscript deals with the sorption of Am(III) and Eu(III) from pH medium using chitosan functionalized with dendrimer like polyamidoamine (PAMAM) polymers up to third generation. The PAMAM polymers were introduced into chitosan by two step processes and were characterized by various instrumental techniques like FTIR, XRD, TG-DTA. The sorption process was highly pH dependent for both Am(III) and Eu(III) with increasing trend for higher pH of the solution. Kinetics of equilibration was found to be fast with equilibrium attained in 10 min for both the metal ions. Pseudo 2nd order kinetics mechanism was found to be followed for both Am(III) and Eu(III). The sorption process of Eu(III) was found to fit the Langmuir isotherm model with maximum sorption capacity of 6.01 mg/g. There was no effect on the generation of PAMAM Dendron on the efficiency, kinetics or sorption capacity for Am(III) as well as Eu(III). The synthesized different generation of PAMAM functionalized chitosan is a promising material for removal of actinides and lanthanides from waste water solution.

Management of Acute Admissions of Heart Failure Patients with Kidney Disease

Acute heart failure (HF) admissions are common. They are often associated with prolonged hospitalisations and poor outcomes. One-third of chronic HF patients also suffer from chronic kidney disease (CKD). Hence, acute admissions of HF with CKD are common and are associated with longer length of stay and increased mortality. Hyperkalaemia and acute on chronic renal impairment are important challenges in the management of these cases. Cautious introduction of high-dose diuretic therapy, followed by the re-commencement of renin-angiotensin-aldosterone (RAAS) inhibitors, improves length of stay, quality of life, and prognosis. During an admission on to the medical assessment unit careful monitoring and management of the patient's clinical condition and biochemistry is essential.

Enablers and Barriers of Follow-Up Care: An Experience From an HPV DNA Detection–Based Cervical Cancer Screening Program in Rural India

Background: Success of a cervical cancer screening program is intrinsically linked with appropriate management of women detected positive on screening tests. While routine screening can be done in any setting, the follow-up care of screen positive women is linked with settings that are equipped with diagnostic and treatment facilities, and trained medical providers. In low resource settings, the major obstacles to deliver follow-up care are lack of adequate healthcare infrastructure and trained service providers at district or subdistrict levels. Aim: To assess feasibility of implementing community based interventions to increase uptake of follow-up care of screen positive women in a HPV detection based screening program conducted by Chittaranjan National Cancer Institute (CNCI), Kolkata. Strategy: A network of key stakeholders including government authorities and civil society organizations was developed to deliver continuum of care at the doorsteps of screen positive women. The infrastructure of government's primary health care delivery system was used to set up temporary clinics at district and subdistrict levels. The clinics were organized on prescheduled dates and times that were convenient to the women. Community health workers (CHWs) were trained in community mobilization strategies to increase uptake of follow-up services. All instruments, equipment and consumables required for providing follow-up services were carried to the clinics in a vehicle. Program: The CHWs played a key role in counseling and recalling the screen positive women. The temporary clinics were arranged in the government primary health centers. A team of trained doctors and paramedics provided the diagnostic and treatment services. Colposcopy was performed on all screen positive women using portable colposcopes and guided biopsies were taken as indicated. Women who were eligible for ablative treatment were counseled and treated in the same sitting. All women were advised yearly follow-up. Outcomes: A total of 43,325 women were screened by HC2 test during July 2010 to March 2015, and 2045 (4.7%) women were detected to be high-risk HPV positive. Compliance to first recall was good with 78.6% (1608/2045) of women undergoing diagnostic evaluation at field clinics. But overall compliance to at least one follow-up visit after 1 year was poor (23.2%). Follow-up compliance rate was higher in women who were diagnosed with CIN1 as compared with those with normal diagnosis ( P < 0.001). What was learned: Diagnostic and treatment services could be effectively organized in the community in convergence with existing healthcare delivery system. High compliance to initial diagnostic evaluation and treatment was achieved by making the services available close to the doorsteps of the women. The reasons for low compliance to yearly follow-up were lack of understanding of future cancer risk, unwilling to undergo speculum examination again, and lack of cooperation of spouse/family.

Search for a Hypothetical 16.7 MeV Gauge Boson and Dark Photons in the NA64 Experiment at CERN

We report the first results on a direct search for a new 16.7 MeV boson (X) which could explain the anomalous excess of e^{+}e^{-} pairs observed in the excited ^{8}Be^{*} nucleus decays. Because of its coupling to electrons, the X could be produced in the bremsstrahlung reaction e^{-}Z→e^{-}ZX by a 100 GeV e^{-} beam incident on an active target in the NA64 experiment at the CERN Super Proton Synchrotron and observed through the subsequent decay into a e^{+}e^{-} pair. With 5.4×10^{10} electrons on target, no evidence for such decays was found, allowing us to set first limits on the X-e^{-} coupling in the range 1.3×10^{-4}≲ε_{e}≲4.2×10^{-4} excluding part of the allowed parameter space. We also set new bounds on the mixing strength of photons with dark photons (A^{'}) from nonobservation of the decay A^{'}→e^{+}e^{-} of the bremsstrahlung A^{'} with a mass ≲23  MeV.

1D-2D hybrids as efficient optoelectronic materials: a study on graphitic carbon nitride nanosheets wrapped with zinc oxide rods

Zinc oxide (ZnO) nanorods (NRs) wrapped with graphitic carbon nitride (GCN) nanosheet (NS) hybrids have been synthesized by a simple chemical process. The as-prepared samples are characterized by X-ray diffraction, field emission scanning electron microscopy, high resolution transmission electron microscopy, Fourier transformed infrared spectroscopy, UV-Vis spectroscopy and photoluminescence spectroscopy. The images obtained from the transmission electron microscopic study and the existence of C-N stretching modes as observed from Fourier transform infrared spectroscopy confirm the successful attachment of GCN NSs onto the ZnO NRs. It is seen that hybrid samples show broad photoluminescence (PL) emission with enhanced defect related emission along with a quenching effect due to the charge transfer mechanism. The results have been explained by taking into consideration the three different types of electron transitions occurring within the type-II band structure of the hybrid samples. Moreover a study on the conductivity of the samples is carried out under dark conditions and also under ultraviolet (UV) light irradiation. It is observed that the hybrid samples show significantly improved conductivity under both dark and UV irradiated conditions. The absorbance of the samples in the UV range shows better conductivity under UV conditions as compared to dark conditions.

Unraveling doping induced anatase–rutile phase transition in TiO2 using electron, X-ray and gamma-ray as spectroscopic probes

The present work reports the microscopic details of anatase (A) to rutile (R) phase transformation in a Mn-doped TiO₂ system.

Graphene-Anchored p-Type CuBO2 Nanocrystals for a Transparent Cold Cathode

CuBO₂ nanostructures were synthesized by employing a low-cost hydrothermal technique to combine into the CuBO₂-RGO nanocomposite for the first time using chemically prepared graphene sheets. The nanohybrid samples were characterized for structural information using X-ray diffraction (XRD) that revealed the proper crystalline phase formation of CuBO₂ unaltered by composite formation with graphene. Raman spectroscopic studies were employed to confirm the presence of graphene. A morphological study with field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) suggested the proper wrapping of RGO sheets over CuBO₂ nanocubes. Moreover, the close proximity of lattice planes of CuBO₂ and RGO to each other was observed in high-resolution TEM studies that were correlated with the Raman spectroscopic studies. Finally, the samples were characterized to study the field emission (FE) properties of the same using a laboratory-made high-vacuum field-emission setup. Finite-element-based theoretical simulation studies were carried out to explain and compare the field emission properties with the experimental results. The FE properties of the composite samples were found to be tuned by the nature of wrapping the RGO sheets over the CuBO₂ nanocubes, which was typically dependent upon the spiky morphology of the nanocubes.

Insights into Cruciform Sample Design

Four different cruciform sample designs, based on the work of Abu-Farha et al., were studied in this paper. Key features of this design are a recessed pocket with fillet and re-entrant corners. These samples were shown via digital image correlation to achieve widely differing strain values inside and outside the pocket. From the results of these tests, there are two competing failure mechanisms in the sample. The pocket region is affected by stress concentrations caused by the fillet, and re-entrant notches lead to strain limited constraints similar to diffuse and localized necks in uniaxial samples. Balancing these two constraints determines the success or premature failure of the sample.

Removal of radiocesium from low level radioactive effluents by hexacyanoferrate loaded synthetic zeolite: laboratory to pilot plant scale demonstration

Present paper reports removal of radiocesium from low level waste using a modified sorbent (13X-CFC) prepared by in-situ precipitation of potassium copper hexacyanoferrate(II) inside the macropores of a synthetic zeolite. The Cs exchange isotherm of the sorbent is established and it found to follow Fruendlich absorption isotherm equation. It is varified that presence of hexacyanoferrate on zeolite facilitates rapid Cs uptake performance. This is further confirmed in laboratory scale column tests, wherein excellent Cs removal performance from low level waste simulant was observed even at higher flow rates (40 bed volumes per hour). The utility of the sorbent is established through successful demonstration in a pilot scale (50 L) trial with almost complete removal of 137Cs from more than 14,000 bed volumes of actual low level waste. The sorbent, owing to its low cost and excellent 137Cs removal performance, is expected to find application in treatment of very low active waste streams.

Search for Invisible Decays of Sub-GeV Dark Photons in Missing-Energy Events at the CERN SPS

We report on a direct search for sub-GeV dark photons (A^{'}), which might be produced in the reaction e^{-}Z→e^{-}ZA^{'} via kinetic mixing with photons by 100 GeV electrons incident on an active target in the NA64 experiment at the CERN SPS. The dark photons would decay invisibly into dark matter particles resulting in events with large missing energy. No evidence for such decays was found with 2.75×10^{9} electrons on target. We set new limits on the γ-A^{'} mixing strength and exclude the invisible A^{'} with a mass ≲100  MeV as an explanation of the muon g_{μ}-2 anomaly.