Role of the Recoil Ion in Single-Electron Capture and Single-Ionization Processes for Collisions of Protons with He and Ar Atoms

In this work the single-electron capture and single-ionization processes are studied for proton collisions with He and Ar atoms at impact energies in the range 25–100 keV. Classical trajectory Monte Carlo simulations are benchmarked against experimental data obtained at the reaction microscope in Bariloche, Argentina, which employs the cold target recoil-ion momentum spectroscopy technique. Special emphasis is placed on describing the momentum transfer to the recoil ion for these collision systems

Properties of Mosquito Repellent-Plasticized Poly(lactic acid) Strands

This article belongs to the Special Issue Thermal and Rheological Characterization of Polymeric Materials[Abstract] Poly(lactic acid) (PLA) is an attractive candidate for replacing petrochemical polymers because it is fully biodegradable. This study investigated the potential of PLA as a sustainable and environmentally friendly alternative material that can be developed into commercially viable wearable mosquito repellent devices with desirable characteristics. PLA strands containing DEET and IR3535 were prepared by twin screw extrusion compounding and simultaneously functioned as plasticizers for the polymer. The plasticizing effect was investigated by thermal and rheological studies. DSC studies showed that the addition of DEET and IR3535 into PLA strands reduced the glass transition temperature consistent with predictions of the Fox equation, thus proving their efficiency as plasticizers. The rheology of molten samples of neat PLA and PLA/repellents blends, evaluated at 200 °C, was consistent with shear-thinning pseudoplastic behaviour. Raman studies revealed a nonlinear concentration gradient for DEET in the PLA strand, indicating non-Fickian Type II transport controlling the desorption process. Release data obtained at 50 °C showed initial rapid release followed by a slower, near constant rate at longer times. The release rate data were fitted to a novel modification of the Peppas-Sahlin desorption modelThis work was financially supported from the Deutsche Forschungsgemeinschaft (DFG), Germany [Grant number AN 212/22-2] and University of Pretoria (UP) Postdoctoral Fellowship programme. The research has been also supported by Spanish MINECO grant MTM2017-82724-R through the ERDFDeutsche Forschungsgemeinschaft (DFG); AN 212/22-2https://www.mdpi.com/journal/molecules/special_issues/Thermal_Rheological_Polymeric_Material

A study of solvent debinding variables on Ti6Al4V green bodies

Debinding is one of the most critical and time consuming stage in metal injection moulding (MIM). German and Bose (1997) reported that early debinding practice relied on thermal binder degradation, requiring up to 300 hours for complete binder removal. Today multi-stage debinding techniques are introduced cutting down the debinding time to as little as 2 hours. This work investigates solvent debinding variables for samples made by MIM Ti6Al4V powder prior to thermal debinding. Solvent debinding is carried out in n-heptane. Wax and stearic acid are the target binder components being leached out from the green bodies, with wax as the major constituent in the binder formulation. Debinding is conducted at 50, 55, 60 and 65°C for 1-4 hours at each temperature. Weight loss measurements were done. For porosity and surface appearance, scanning electron microscope (SEM) analysis and visual inspection were done.Samples debound at 65°C showed an appreciable amount of mass loss; however, surface cracks and warping were observed. A 60°C temperature and time of 4 hours demonstrated best results i.e. a satisfactory mass loss, absence of surface cracks and no warping. Mass loss is directly proportional to temperature and time. SEM results are discussed in the paper.http://www.ttp.net/1022-6680.htmlhb201

On the nature of the first transient Z-source XTE J1701-462: its accretion disk structure, neutron star magnetic field strength, and hard tail

Using the data from the Rossi X-Ray Timing Explorer satellite, we investigate the spectral evolution along a "Z" track and a "v" track on the hardness-intensity diagrams of the first transient Z source XTE J1701-462. The spectral analyses suggest that the inner disk radius depends on the mass accretion rate, in agreement with the model prediction, R_in \propto ((dM/dt)_disk)^{2/7}, for a radiation pressure dominated accretion disk interacting with the magnetosphere of a neutron star (NS). The changes in the disk mass accretion rate (dM/dt)_disk are responsible for the evolution of the "Z" or "v" track. The radiation pressure thickens the disk considerably, and also produces significant outflows. The NS surface magnetic field strength, derived from the interaction between the magnetosphere and the radiation pressure dominated accretion disk, is ~(1--3)X10^9 G, which is possibly between normal atoll and Z sources. A significant hard tail is detected in the horizontal branches and we discuss several possible origins of the hard tail

USA Observation of Spectral and Timing Evolution During the 2000 Outburst of XTE J1550-564

We report on timing and spectral observations of the 2000 outburst of XTE J1550-564 made by the Unconventional Stellar Aspect (USA) Experiment on board the Advanced Research and Global Observation Satellite (ARGOS). We observe a low-frequency quasi-periodic oscillation (LFQPO) with a centroid frequency that tends to increase with increasing flux and a fractional rms amplitude which is correlated with the hardness ratio. The evolution of the hardness ratio (4--16 keV/1--4 keV) with time and source flux is examined. The hardness-intensity diagram (HID) shows a cyclical movement in the clockwise direction and possibly indicates the presence of two independent accretion flows. We observe a relationship between the USA 4--16 keV count rate and radio observations and discuss this in the context of previously observed correlations between X-ray, radio, optical and IR data. We examine our results in the context of models invoking two accretion flows: a thin disk and a hot sub-Keplerian flow.Comment: 11 pages, 2 figure

Defining Meyer's loop-temporal lobe resections, visual field deficits and diffusion tensor tractography

Anterior temporal lobe resection is often complicated by superior quadrantic visual field deficits (VFDs). In some cases this can be severe enough to prohibit driving, even if a patient is free of seizures. These deficits are caused by damage to Meyer's loop of the optic radiation, which shows considerable heterogeneity in its anterior extent. This structure cannot be distinguished using clinical magnetic resonance imaging sequences. Diffusion tensor tractography is an advanced magnetic resonance imaging technique that enables the parcellation of white matter. Using seed voxels antero-lateral to the lateral geniculate nucleus, we applied this technique to 20 control subjects, and 21 postoperative patients. All patients had visual fields assessed with Goldmann perimetry at least three months after surgery. We measured the distance from the tip of Meyer's loop to the temporal pole and horn in all subjects. In addition, we measured the size of temporal lobe resection using postoperative T1-weighted images, and quantified VFDs. Nine patients suffered VFDs ranging from 22% to 87% of the contralateral superior quadrant. In patients, the range of distance from the tip of Meyer's loop to the temporal pole was 24–43 mm (mean 34 mm), and the range of distance from the tip of Meyer's loop to the temporal horn was –15 to +9 mm (mean 0 mm). In controls the range of distance from the tip of Meyer's loop to the temporal pole was 24–47 mm (mean 35 mm), and the range of distance from the tip of Meyer's loop to the temporal horn was –11 to +9 mm (mean 0 mm). Both quantitative and qualitative results were in accord with recent dissections of cadaveric brains, and analysis of postoperative VFDs and resection volumes. By applying a linear regression analysis we showed that both distance from the tip of Meyer's loop to the temporal pole and the size of resection were significant predictors of the postoperative VFDs. We conclude that there is considerable variation in the anterior extent of Meyer's loop. In view of this, diffusion tensor tractography of the optic radiation is a potentially useful method to assess an individual patient's risk of postoperative VFDs following anterior temporal lobe resection

Temporal Properties of Cygnus X-1 During the Spectral Transitions

We report the results from our timing analysis of 15 RXTE observations of Cygnus X-1 throughout its 1996 spectral transitions. The entire period can be divided into 3 distinct phases: (1) transition from the hard to soft state, (2) soft state, and (3) transition from the soft state back to the hard state. The observed X-ray properties in phases 1 and 3 are remarkably similar, suggesting that the same physical processes are likely involved in triggering such transitions. The power density spectrum (PDS) during the transition can be characterized by a red noise component, followed by a white noise component which extends to roughly 1-3 Hz where it is cut off, and a steeper power law at higher frequencies. The X-ray flux also exhibits apparent quasi-periodic oscillation (QPO) with the centroid frequency varying in the range of 4-12 Hz. The QPO shows no correlation with the source flux, but becomes more prominent at higher energies. This type of PDS bears resemblance to that of other black hole candidates often observed in a so-called very high state, although the origin of the observed QPO may be very different. The low-frequency red noise has not been observed in the hard state, thus seems to be positively correlated with the disk mass accretion rate which is presumably low in the hard state and high in the soft state; in fact, it completely dominates the PDS in the soft state. In the framework of thermalComptonization models, Cui et al. (see astro-ph/9610071 and astro-ph/9610072) speculated that the difference in the observed spectral and timing properties between the hard and soft states is due to the presence of a ``fluctuating'' Comptonizing corona during the transition. Here we present the measured hard X-ray time lags and coherence functions between various energy bands, and show that the results strongly support such a scenario.Comment: AASTex file. 29 pages including 11 figures. To appear in Ap

Importance of access to epilepsy monitoring units during the COVID-19 pandemic: Consensus statement of the International League against epilepsy and the International Federation of Clinical Neurophysiology

Restructuring of healthcare services during the COVID-19 pandemic has led to lockdown of Epilepsy Monitoring Units (EMUs) in many hospitals. The ad-hoc taskforce of the International League Against Epilepsy (ILAE) and the International Federation of Clinical Neurophysiology (IFCN) highlights the detrimental effect of postponing video-EEG monitoring of patients with epilepsy and other paroxysmal events. The taskforce calls for action to continue functioning of Epilepsy Monitoring Units during emergency situations, such as the COVID-19 pandemic. Long-term video-EEG monitoring is an essential diagnostic service. Access to video-EEG monitoring of the patients in the EMUs must be given high priority. Patients should be screened for COVID-19, before admission, according to the local regulations. Local policies for COVID-19 infection control should be adhered to during the video-EEG monitoring. In cases of differential diagnosis where reduction of antiseizure medication is not required, consider home video-EEG monitoring as an alternative in selected patients

Cellulose acetate/organoclay nanocomposites as controlled release matrices for pest control applications

This study aimed to develop cellulose-based polymer matrices as controlled release devices for plant-based insect repellents and attractants, with the aim of finding sustainable and environmentally friendly pest control methods for agricultural applications. Citronellol, terpineol and methyl salicylate were the selected active compounds for this study. Their compatibility with cellulose diacetate was predicted using Hansen Solubility Parameters, which predicted terpineol as the most compatible with cellulose diacetate, followed by methyl salicylate and citronellol. This was consistent with the plasticization efficiency trend from DMA results of solvent cast cellulose diacetate films containing the active compounds. The chemical identity of the films and cellulose diacetate-active compound intermolecular interactions were verified by FTIR. TGA demonstrated the thermal stability of cellulose diacetate/active compound/clay formulations at temperatures not exceeding 170 °C. Cellulose diacetate/organoclay nanocomposite matrices containing the active compounds at 35 wt-% were prepared by twin screw extrusion compounding, with the active compounds also functioning as plasticizers. The amount of active compound in the strands was determined by solvent extraction and TGA. Both methods showed that small amounts of active compound were lost during the compounding process. SEM demonstrated the effect of organoclay on the internal morphology of the matrix, whereas TEM showed clay dispersion and intercalation within the matrix. The matrix served as a reservoir for the active compounds while simultaneously controlling their release into the environment. Release profiles, obtained through oven ageing at 40 °C for 70 days, were fitted to existing Log-logistic and Weibull models, and novel Diffusion and Modified Weibull release models. Citronellol was released the fastest, followed by methyl salicylate and terpineol. The findings suggest that cellulose diacetate/organoclay strands are promising controlled-release matrices for pest control purposes.he Paper Manufacturers Association of South Africa (PAMSA) and the Department of Science and Innovation (DSI) and the National Research Foundation of South Africa (NRF).https://link.springer.com/journal/10570hj2023Chemical EngineeringUP Centre for Sustainable Malaria Control (UP CSMC

RXTE Observation of Cygnus X-1 In Its High State

We present the results from the RXTE observations of Cygnus X-1 in its high state. In the energy range of 2-200 keV, the observed X-ray spectrum can be described by a model consisting of a soft blackbody component and a broken power-law with a high energy cutoff. The low energy spectrum (below about 11 keV) varies significantly from observation to observation while the high energy portion changes little. The X-ray flux varies on all timescales down to milliseconds. The power density spectrum (PDS) can be characterized by excess red noise (``1/f'') at low frequencies and a white noise component that extends to 1-3 Hz before being cut off. At higher frequencies, the PDS becomes power-law again, with a slope of roughly -2 (i.e., ``1/f^2''). Broad peaks in the range of 3-9 Hz are present, and might be due to quasi-periodic oscillations. The PDS shows interesting spectral dependence: the 1/f component becomes more prominent when the low-energy spectrum becomes softer. The difference in the observed spectral and timing properties between the low and high states is qualitatively consistent with a simple ``fluctuating corona'' model.Comment: 11 pages including 3 figures, LaTeX (aaspp4.sty). Accepted for publication in ApJ Letter