Donut and dynamic polarization effects in proton channeling through carbon nanotubes

We investigate the angular and spatial distributions of protons of the energy of 0.223 MeV after channeling through an (11,~9) single-wall carbon nanotube of the length of 0.2 $\mu$m. The proton incident angle is varied between 0 and 10 mrad, being close to the critical angle for channeling. We show that, as the proton incident angle increases and approaches the critical angle for channeling, a ring-like structure is developed in the angular distribution - donut effect. We demonstrate that it is the rainbow effect. When the proton incident angle is between zero and a half of the critical angle for channeling, the image force affects considerably the number and positions of the maxima of the angular and spatial distributions. However, when the proton incident angle is close to the critical angle for channeling, its influence on the angular and spatial distributions is reduced strongly. We demonstrate that the increase of the proton incident angle can lead to a significant rearrangement of the propagating protons within the nanotube. This effect may be used to locate atomic impurities in nanotubes as well as for creating nanosized proton beams to be used in materials science, biology and medicine.Comment: 17 pages, 14 figure

Parathion content in individual tissues of acutely poisoned rats

Određivan je paration u mozgu, jetri i mišićnom tkivu pacova nakon jednokratne intraperitonealne aplikacije otrova. Određivanje je vršeno metodom gasno-tečne hromatografije, hromatografom firme Varian, model 2100-20, opremljenim fosfornim detektorom. Kolona je punjena smešom dve stacionarne faze (silikonsko ulje DC-200 i QF-1) na Chromosorb W-HMDS, kao nosaču. U mozgu nisu nađene merljive količine parationa. Takođe, nije nađen paration u jetri i trbušnim mišićima u toku prvih 60 minuta trovanja. U dužim vremenskim intervalima nađene količine parationa iznosile su 0,125-7,158 µg/g tkiva.Parathion determinations were carried out in brain liver and muscle tissues of the rats poisoned by a single intraperitoneal injection, using gas-liquid chromatography. »Varian« chromatograph, model 2100-20, was used, equipped with a phosphorus detector. The column was packed with a mixture of two stationary phases (silicone oil DC-200 and OF-1) on Chromosorbe W-HMDS. No measurable quantities of parathion were found in the brain. During the first 60 minutes after the poison injection there was no parathion in the liver or abdominal muscles either. In longer time intervals, the detected quantities of parathion were in the range from 0.125 to 7.158 µg/g of the tissue

Some clinical and biochemical parameters in workers occupationally exposed to pesticldes

U radu je ispitivana profesionalna izloženost radnika pesticidima i njihov uticaj na pojedine kliničke i biohemijske parametre. Klinički i biohemijski pokazatelji efekata pesticida praćeni su standardnim internističkim pregledom, rendgenografskim, elektrokardiografskim, spirometrijskim i laboratorijskim istraživanjima. Dobijeni rezultati su upoređeni sa rezultatima kontrolne grupe, a dobijene razlike su testirane Studentovim t-testom i x2-testom. Osim toga ispitivana je i linearna korelacija vrednosti pojedinih parametara zdravstvenog stanja i dužine izloženosti. Razmatrani su mogući mehanizmi nastajanja uočenih promena posmatranih parametara zdravstvenog stanja kod grupe radnika profesionalno Izložene pesticidima.Occupational exposure to pesticides and its effect on some clinical and biochemical parameters were studied in a group of workers. Radiographic, electrocardiographic and spirometric examinations were performed in addition to standard medical check-up. Laboratory tests included blood and urine analyses The results were compared with the data for the control group and the differences were analysed by means of Student\u27s t-test and the chi-squared test. There was a linear correlation between certain health parameters and length of exposure

Some neurophysiological, psychomotor, and psychological parameters in workers after long-term exposure to cholinesterase-inhibiting insecticides

U radu je ispitivana profesionalna izloženost radnika insekticidima inhibitorima holinesteraze i njihov uticaj na pojedine neurofiziološke, psihomotorne i psihološke parametre. Praćenje parametara je obuhvatilo merenje aktivnosti holinesteraze eritrocita, bioelektrične aktivnosti kore velikog mozga, reakcionih vremena, vizuelne diskriminacije, vizuelne identifikacije i profil indeks emocija. Dobijeni rezultati su upoređivani sa rezultatima kontrolnih grupa, a dobijene razlike su testirane Studentovim t-testom. Osim toga ispitivana je i linearna korelacija pojedinih parametara istraživanja. Razmatrani su mogući mehanizmi nastajanja uočenih promena posmatranih parametara kod grupe radnika profesionalno izloženih insekticidima inhibitorima holinesteraze.The paper deals with the effects of insecticides, cholinesterase inhibitors, on certain neurophysiological, psychomotor, and psychological parameters in occupationally exposed workers. The parameters measured were: the activities of erythrocyte cholinesterase, the bioelectrical activity of the cerebrum core, reaction times, visual discrimination, visual identification and the emotion index profile. The results were compared to the results from control groups, and the differences were analysed by Student\u27s test. The linear correlation of certain parameters was also examined. Possible mechanisms responsible for the changes in parameters are discussed

Transmission Studies With Ion Beams Within FAMA

FAMA is a user facility for materials science with low-energy ion beams in the Vinča Institute of Nuclear Sciences, Belgrade, Serbia. It includes a heavy ion source, a light ion source, two channels for modification of materials, and two channels for analysis of materials. Recently, the designing of a channel for transmission studies within FAMA has begun. The initial studies to be undertaken in this channel are related to the rainbow e ffects with very thin electrostatic lenses and two-dimensional materials.27th Russian Particle Accelerator Conference (RuPAC'21), Alushta, Russia, 27 September-01 October 202

Dynamic polarization effects on the angular distributions of protons channeled through carbon nanotubes in dielectric media

The best level of ordering and straightening of carbon nanotube arrays is often achieved when they are grown in a dielectric matrix, so such structures present the most suitable candidates for future channeling experiments with carbon nanotubes. Consequently, we investigate here how the dynamic polarization of carbon valence electrons in the presence of various surrounding dielectric media affects the angular distributions of protons channeled through (11,~9) single-wall carbon nanotubes. Proton speeds between 3 and 10 a.u., corresponding to energies of 0.223 and 2.49 MeV, are chosen with the nanotube's length varied between 0.1 and 1 $\mu$m. We describe the repulsive interaction between a proton and the nanotube's atoms in a continuum-potential approximation based on the Doyle-Turner potential, whereas the attractive image force on a proton is calculated using a two-dimensional hydrodynamic model for the dynamic response of the nanotube valence electrons, while assigning to the surrounding medium an appropriate (frequency dependent) dielectric function. The angular distributions of channeled protons are generated using a computer simulation method which solves the proton equations of motion in the transverse plane numerically. Our analysis shows that the presence of a dielectric medium can strongly affect both the appearance and positions of maxima in the angular distributions of channeled protons.Comment: 14 pages, 11 figures, Accepted for publication in Phys. Rev.

Mass spectrometric investigation of silver clusters

Silver clusters were produced by two different synthesis procedures, related with different reduction species. PVA (polyvinyl alcohol) was successfully utilized as a source to reduce silver (Ag) metal ions without using any additional reducing agents to obtain Ag clusters. Silver clusters with atoms numbering 5-29 are registered through mass spectrometry using MALDI TOF and MALDI TOF/TOF techniques. Analysis showed that clusters with magic numbers are the largest, while those with an odd number of atoms are larger than clusters with an even number of atoms. Stability of these molecules, magic number actually, is in relation with their electronic configuration

Titration to target dose of bisoprolol vs. carvedilol in elderly patients with heart failure: the CIBIS-ELD trial

AIMS: Various beta-blockers with distinct pharmacological profiles are approved in heart failure, yet they remain underused and underdosed. Although potentially of major public health importance, whether one agent is superior in terms of tolerability and optimal dosing has not been investigated. The aim of this study was therefore to compare the tolerability and clinical effects of two proven beta-blockers in elderly patients with heart failure. METHODS AND RESULTS: We performed a double-blind superiority trial of bisoprolol vs. carvedilol in 883 elderly heart failure patients with reduced or preserved left ventricular ejection fraction in 41 European centres. The primary endpoint was tolerability, defined as reaching and maintaining guideline-recommended target doses after 12 weeks treatment. Adverse events and clinical parameters of patient status were secondary endpoints. None of the beta-blockers was superior with regards to tolerability: 24% [95% confidence interval (CI) 20-28] of patients in the bisoprolol arm and 25% (95% CI 21-29) of patients in the carvedilol arm achieved the primary endpoint (P= 0.64). The use of bisoprolol resulted in greater reduction of heart rate (adjusted mean difference 2.1 b.p.m., 95% CI 0.5-3.6, P= 0.008) and more, dose-limiting, bradycardic adverse events (16 vs. 11%; P= 0.02). The use of carvedilol led to a reduction of forced expiratory volume (adjusted mean difference 50 mL, 95% CI 4-95, P= 0.03) and more, non-dose-limiting, pulmonary adverse events (10 vs. 4%; P < 0.001). CONCLUSION: Overall tolerability to target doses was comparable. The pattern of intolerance, however, was different: bradycardia occurred more often in the bisoprolol group, whereas pulmonary adverse events occurred more often in the carvedilol group. This study is registered with controlled-trials.com, number ISRCTN34827306

Implications of serial measurements of natriuretic peptides in heart failure: insights from BIOSTAT‐CHF

No abstract available

A Comparative Analysis of Techniques for PAPR Reduction of OFDM Signals

In this paper the problem of high Peak-to-Average Power Ratio (PAPR) in Orthogonal Frequency-Division Multiplexing (OFDM) signals is studied. Besides describing three techniques for PAPR reduction, SeLective Mapping (SLM), Partial Transmit Sequence (PTS) and Interleaving, a detailed analysis of the performances of these techniques for various values of relevant parameters (number of phase sequences, number of interleavers, number of phase factors, number of subblocks) depending on applied technique, is carried out. Simulation of these techniques is run in Matlab software. Results are presented in the form of Complementary Cumulative Distribution Function (CCDF) curves for PAPR of 30000 randomly generated OFDM symbols. Simulations are performed for OFDM signals with 32 and 256 subcarriers, oversampled by a factor of 4. A detailed comparison of these techniques is made based on Matlab simulation results