bluuebunny/crossref_metadata_2025 huggingface dataset:
Unsupervised machine learning can delineate central sulcus by using the spatiotemporal characteristic of somatosensory evoked potentials
Authors: Asman Priscella , Prabhu Sujit , Bastos Dhiego , Tummala Sudhakar , Bhavsar Shreyas , McHugh Thomas Michael , Ince Nuri Firat
Published: April 2021

Objective. Somatosensory evoked potentials (SSEPs) recorded with electrocorticography (ECoG) for central sulcus (CS) identification is a widely accepted procedure in routine intraoperative neurophysiological monitoring. Clinical practices test the short-latency SSEPs for the phase reversal over strip electrodes. However, assessments based on waveform morphology are susceptible to variations in interpretations due to the hand area’s localized nature and usually require multiple electrode placements or electrode relocation. We investigated the feasibility of unsupervised delineation of the CS by using the spatiotemporal patterns of the SSEP captured with the ECoG grid. Approach. Intraoperatively, SSEPs were recorded from eight patients using ECoG grids placed over the sensorimotor cortex. Neurosurgeons blinded to the electrophysiology identified the sensory and motor gyri using neuronavigation based on sulcal anatomy. We quantified the most discriminatory time points in SSEPs temporal profile between the primary motor (M1) and somatosensory (S1) cortex using the Fisher discrimination criterion. We visualized the amplitude gradient of the SSEP over a 2D heat map to provide visual feedback for the delineation of the CS based on electrophysiology. Subsequently, we employed spectral clustering using the entire the SSEP waveform without selecting any time points and grouped ECoG channels in an unsupervised fashion. Main results. Consistently in all patients, two different time points provided almost equal discrimination between anterior and posterior channels, which vividly outlined the CS when we viewed the SSEP amplitude distribution as a spatial 2D heat map. The first discriminative time point was in proximity to the conventionally favored ∼20 ms peak (N20), and the second time point was slightly later than the markedly high ∼30 ms peak (P30). Still, the location of these time points varied noticeably across subjects. Unsupervised clustering approach separated the anterior and posterior channels with an accuracy of 96.3% based on the time derivative of the SSEP trace without the need for a subject-specific time point selection. In contrast, the raw trace resulted in an accuracy of 88.0%. Significance. We show that the unsupervised clustering of the SSEP trace assessed with subdural electrode grids can delineate the CS automatically with high precision, and the constructed heat maps can localize the motor cortex. We anticipate that the spatiotemporal patterns of SSEP fused with machine learning can serve as a useful tool to assist in surgical planning.
A novel Boundary Element model for solving stationary inhomogeneous heat conduction problems
Authors: Barcelos H M , Loeffler C F , Lara L O C
Published: April 2021

A new formulation of BEM applied to steady heat conduction problems, governed by the inhomogeneous Laplace Equation will be presented. The thermal property is isotropic, but varies according to a function known throughout the domain. DIBEM and DST are used together to generate the numerical model. Being used in the interpolation process, two distinct RBF will be used to evaluate the formulation performance. In order to show the generality and capacity of the proposed model, the heat flux variation in a machine tool temperature sensor is calculated. The comparison of the quality of the results achieved is made using FEM.
Correlating ultrasonic pulse velocity and compression resistance of dry concretes at 54 kHz and 500 kHz
Authors: Santos E W J , Pinto E S F , Santos F D G , Dourado T C , Costa-Félix R P B
Published: April 2021

Nondestructive tests applying ultrasound in concrete is used for more than halfcentury. However, the difficulties in making transit time measurement in heterogeneous media have limited the spread use of these applications. The objective of this work is to present a metrological protocol to determine the correlation between the compressive strength of concrete specimens with about 1 year of cure with their respective longitudinal ultrasonic pulse velocity (UPV). From excitation signals sent through a tunable square wave using the direct transmission method, two pairs of transducers with central frequencies of 54 kHz and 500 kHz were used. UPV is determined by the relation between the length and the propagation time of flight the waveform travels within the concrete test specimens. The pieces were constructed according to ABNT NBR 5738:2015 (Concrete – Procedure for molding and curing of concrete specimens) and tested for compression according to ABNT NBR 5739:2007 (Cylindrical specimen compression test – Method of the test). The preliminary results obtained discloses a coherent increase in UPV and concrete strength. Moreover, the highest frequency leads to higher UPV. With the findings presented in this paper, it is possible to define a dual-frequency nondestructive ultrasound method to evaluate concrete resistance more reliable than the traditional approach.
Determining the LOD and LOQ in steel alloys analysis using NITON spectrometer
Authors: Krummenauer A , Dias P R , Veit H M
Published: April 2021

Low concentrations standards spectrometric analysis using the NITON spectrometer require the LOD and LOQ to be determined from the analytical method along with identification of the sample matrix. The LOD (the smallest quantity of analyte that can be detected but not necessarily quantified) and LOQ (the smallest quantity of analyte that can be measured with acceptable accuracy) must be determined for each individual matrix because the energy dispersive X-ray fluorescence (EDXRF) method used by NITON spectrometer is strongly influenced by the matrix effect. This study determined LODs and LOQs for steel alloy samples using certified reference materials with low analyte concentration and compared the calculated LODs and LOQs to those specified by the manufacturer using a two-way ANOVA analysis for each chemical element.
Ensuring the validity of results of hydrophone calibration by a mutual comparison calibration method
Authors: Oliveira E G , Alvarenga A V , Costa-Felix R P B
Published: April 2021

Hydrophone calibration is one of the most important basic metrology activities in ultrasound. Hydrophones are used in many different calibrations and testing methods in industry, for instance, the evaluation of medical electrical equipment basic safety and essential performance. Ensuring the validity of results of metrological services is a major concern for any laboratory. Primary calibration of measuring instrument or standard is a widely understood way to assure good results, despite it is not enough, it is not the unique way, neither it is easy to get in some circumstances. For instance, hydrophone calibration is a service restricted to a few laboratories worldwide, which demands a logistic effort and may be quite expensive. An alternative method to guarantee the traceability by in-house check is of interest. This paper presents a method to ensure the traceability of hydrophones after mutual calibrations. Eight previously calibrated hydrophones from different manufactures and characteristics (membrane and needle) were mutually calibrated, by comparison, all of them acting as standards and calibration items. Calibrations were performed from 1 MHz to 10 MHz and the results were evaluated by pair-difference chi-squared statistics. Uncertainties typically laid between 6% to 13% and sensitivities were between 33 to 318 nV Pa−1. After statistics analyses, 4 hydrophones were considered reliable to be used as standards, as their sensitivity keep on stable even after several years since the last calibration. The method can be used by the industry, accredited laboratories, or national metrology institutes to perform functional checks for virtually any measuring instrument or standard, being the limit the number of available devices to properly apply the statistical analysis.
Evaluation of measurement uncertainty of speed of sound in soybean oil
Authors: Oliveira P A , Baesso R M , Alvarenga A V , Costa-Félix R P B
Published: April 2021

Ultrasound can be used to measure several physical and acoustic properties of oils and fuels. However, most studies do not introduce an assessment of measurement uncertainty. It is well known that uncertainty assessment is important to ensure the quality of measurement results. This work presents the evaluation of the factors that influence the measurement uncertainty of the speed of sound in soybean oil. A detailed uncertainty budget of measurement was shown. The speed of sound in soybean oil was measured by the pulse-echo technique (@ 1 MHz), and the result was 1483.4 m·s−1 ± 2.8 m·s−1 (k = 1.96; p = 0.95).
Monitoring and evaluation of relationship marketing initiatives in service companies: proposition of a multicriteria model for selecting indicators and metrics
Authors: Meneses Cristiana Valente , Almeida Maria Fatima Ludovico de
Published: April 2021

With an attempting to fill the research gap concerning common metrics for advancing research in the field of relationship marketing, this paper aims to propose a conceptual model for monitoring and evaluating relationship marketing initiatives carried out by service companies, with the support of a hybrid multicriteria decision-making method. To demonstrate the applicability of this conceptual model in the context of a service company in Brazil, an empirical study focusing on a relationship marketing initiative of Light SESA was developed during the applied phase of the research. As main results, we can highlight the tool for selecting and hierarchizing indicators and respective metrics; and a consistent set of indicators, aiming at the continuous improvement of RM initiatives in service companies.
Understanding the Radiation Thermometers
Authors: Sohn R S T M
Published: April 2021

Radiation thermometers use the laws of thermal radiation to compute the temperature as a function of the measured spectral radiance. The more precise calculations involve the integration of Planck’s Law, which turns the mathematical developments more complex. In this article, whenever possible we use the concept of monochromatic radiation thermometers, which has the advantage of facilitating mathematical developments and allowing the reader to obtain more easily an overview of the instrument behaviour. In addition, we deal with three important types of thermometers: total radiation, spectral band, and ratio thermometers. Some concepts such as radiance and exitance were also presented.
Development and validation of ICP OES methodologies for the determination of metals in powder milk for in proficiency test applications
Authors: Câmara V , Araújo T , Caciano de Sena R , Osorio A , Almeida M
Published: April 2021

The main purpose of this work was the development and validation of methods for measuring the macro and microelements (Ca, Na, Mg, P, Fe, and Zn) in powder milk by inductively coupled plasma optical emission spectrometry (ICP OES). The validated methods were applied for measuring these elements in commercial samples in order to choose a suitable mix sample to prepare a reference material batch and use it for organizing a proficiency test. This comparison will be used to evaluate the performance of national laboratories for measuring the mass fraction of essential elements in powder milk. Samples were digested in a microwave reaction system and the elements were measured using the external calibration approach. The standard uncertainty for the mass fractions of Mg, P, Fe and Zn ranged from 1.2% to 2.8%. The method accuracy was evaluated using certified reference material (SRM 1849a) from the National Institute of Standards and Technology (NIST). The results obtained from the SRM 1849a and the measured values with the proposed methodologies was checked, and the results obtained for Mg, P, Fe, and Zn were considered consistent with the certified values, but not for Ca and Na. In this case, we need to perform additional studies in order to reevaluate these last two methods. After we checked the performance of methods, five commercial samples were chosen to determine the mass fraction of Mg, P, Fe, and Zn. Among these samples, in only one all elements were present at a suitable mass fraction for organizing a proficiency test.
Analysis and development of optical methods to re-use optical stimulated luminescent dosimeters
Authors: Silva C R E , Souza L F , Nogueira M S , Meira-Belo L C
Published: April 2021

Optically Stimulated Luminescence (OSL) is a worldwide used technique in ionizing radiation dosimetry applications, such as personal and environmental monitoring. At the CDTN-CNEN facilities is produced a ceramic detector of α-Al2O3:C, which is used in the routine environmental monitoring and for research purposes. In order to reuse these detectors, it was developed, at Luminescent Dosimetry Laboratory an optical bleaching device, which can operate with green and blue LED illumination modes. The present work describes the use of such device to bleach the optically accessible traps, taking the detectors to its background signal levels. Reference dosimeters α-Al2O3:C commercial and magnesium tetraborate were used also for comparison. As a general procedure, before any irradiation, the used detectors were optically bleached by 36 hours. For the best efficiency of bleaching, after irradiation, the ceramic and commercial aluminum oxide detectors were optically bleached under blue LED light for 3 and 6 hours, respectively. For tetraborate detectors, the required time of optical bleaching was 2 hours, under blue LED illumination.
Calibration of two portable detection devices for in vivo measurements of high-energy photon emitters incorporated by humans in accidental situations
Authors: Soares A. B. , Lucena E. A. , Dantas A. L. A. , Dantas B. M.
Published: April 2021

This work presents the evaluation of the applicability and sensitivity of two portable detection devices specially designed for in vivo measurement of high-energy photon emitters incorporated by humans. The calibration was performed at the In-Vivo Monitoring Laboratory of the IRD. The equipment consist of a NaI(Tl) 3”x3” and a NaI(Tl) 3”x1.5” scintillation detectors assembled on tripods. The detectors and their compact associated electronics are connected via USB cable to a portable PC. Spectrum acquisition and analysis are controlled by specific commercially available software. The calibrations were performed using a standard liquid source of 152Eu contained in 3.3 L polyethylene bottles. The evaluation of the systems is based on the estimation of the minimum committed effective doses associated to the minimum detectable activities, calculated using current biokinetic and dosimetric models available in the literature. The dose detection limits for selected radionuclide of interest in an emergency scenario have shown to be far below 1 mSv, allowing the system to be useful in accident situation.
The use of Augmented Reality for the teaching of dosimetry and metrology of ionizing radiation at IRD
Authors: Gonçalves GL , Delgado JU , Razuck FB
Published: April 2021

It can be said that ionizing radiation are of great importance to society, considering the range of applications of nuclear technology. In this sense, the Institute for Radiation Protection and Dosimetry (IRD) acts in favor of the health and safety of the population and workers exposed to radiation, promoting the preservation of the environment. Therefore, safety is extremely important in the construction of knowledge in Ionizing Radiation Metrology (IRM), due to the use of radioactive sources in its practice. Then, the adoption of safe methodologies is fundamental in the teaching-learning process. Thus, technological tools such as Augmented Reality (AR) are being increasingly used to present, in real environment, virtual elements such as equipment, spaces, concepts and practices, avoiding contact with radioactive sources. In this case, AR is a technology that dramatically displaces the location and time of learning and training. New information and communication technologies are not only powerful and compact tools for delivering AR experiences through personal computers and mobile devices, but also developed and sophisticated in order to combine the real world with improved information interactively. The objective of this work is to demonstrate the possibility of using AR as a pedagogical tool for the learning of radiation protection in IRD courses, as well as assisting in the training of professionals and students in the nuclear safety area.
Fading estimation of SOL-GEL α-Al2O3 detectors
Authors: Polo I O , Caldas L V E
Published: April 2021

The OSL and the TL techniques are used in several fields of radiation dosimetry. The dosimeters are affected by a signal loss in the time between the irradiation and readout (fading). This undesirable characteristic can cause an underestimation of the irradiation dose. The fading estimation of SOL-GEL α-Al2O3 with several different concentrations of impurities is reported. The thermal fading and the light-induced fading of the SOL-GEL α-Al2O3 detectors were estimated. Furthermore, the exponential equations used to interpolate the experimental results were presented.
Influence of the dosimeter calibration conditions on the mean glandular dose in mammography
Authors: Bianchi Vivian C R N , Silva Claudete R E , Da Silva Teógenes A
Published: April 2021

Digital technology in mammography and breast tomosynthesis introduced the use of W and Rh target x-ray tubes with Al, Mo, Rh and Ag additional filters. In Brazil, due to the limited capability of metrology laboratories, x-ray dosimetry in mammography is done with different types of dosimeters that may not be calibrated for such specific clinical beams. The objective of this work was to study the influence of different calibration conditions on the determination of the mean glandular dose in dosimetry in mammography beams.
Preliminary Monte Carlo simulation of non-laser light sources for photodynamic therapy
Authors: Alva-Sánchez M S , Quevedo A , Bonatto A , Pianoschi T
Published: April 2021

In photodynamic therapy (PDT), a photosensitizing agent is administered following irradiation on the target volume. The wavelength beam to activate the photosensitizer is ranging from 400 nm to 800 nm. Such wavelengths are generated by laser and non-laser light sources. However, the use of x-ray induced in photodynamic therapy has been investigated as a combination of radiotherapy and PDT. Moreover, x-rays are used for deeper penetration into tissue, extending the use of this therapy for tumours that would not be reachable by conventional PDT. In general, x-rays with keV to MeV energies are used for X-PDT. The aim of the present work is to investigate the use of monochromatic, low-energy beams for photodynamic therapy applications. Monte Carlo simulations are performed for distinct target volumes irradiated by a nonlaser (low-energy x-rays). Models of soft tissue and a mixture some photosensitizer plus soft tissue were considered. For each case, the energy fluence distribution at a given depth was calculated. A higher percentage difference of ∼20% was found when comparing the beam profile between soft tissue and the mixing Hpd, Photofrin, ALA, PpIX with soft tissue for low energy x-ray. Preliminary results showed that simulated x-ray beams could work for PDT.
Study on electronic equilibrium of 137Cs gamma radiation for 3D printed phantoms using OSL dosimetry
Authors: Villani D. , Rodrigues Jr O. , Mascarenhas Y.M. , Campos L. L.
Published: April 2021

With the popularization of 3D printing technologies, it is now possible to develop patient specific simulators and various other accessories using this technology in medical physics and dosimetry. This work aims to evaluate the electronic equilibrium of 3D printed phantoms using PLA and ABS filaments compared to PMMA for 137Cs gamma rays using OSL dosimetry. A Landauer microStar ii commercial OSL system was commissioned and it was used nanoDot dosimeters. Phantom plates with 2.5, 3.0 and 5.0 mm thickness were used to obtain electronic equilibrium for 137Cs gamma rays. Measurements were compared with PMMA measurements at standard conditions. Results show that measurements with ABS and PLA thicknesses of 2.5 and 3.0 mm presents dosimetry results within irradiation uncertainty. More accuracy is obtained using 3.0 mm for both PLA and ABS phantoms, with differences in less than 0.5%. It can be concluded that PLA and ABS 3D phantom plates has similar properties of PMMA for 137Cs gamma rays dosimetry and can be used for developing dosimetry accessories for this energy photon beam.
Use of CFD by IDQBRN for Radiological Defense Using CTBTO Radionuclide Measurements
Authors: Bonfim C E S , Barbosa F O , da Silva J A V , Brum T
Published: April 2021

The Institute of Chemical, Biological, Radiological and Nuclear Defense (IDQBRN) is part of the Brazilian Army’s Chemical, Biological and Nuclear Defense System (SisDQBRNEx), based on the lines of research conducted in its laboratory complex. Through its Computational Fluid Dynamics Laboratory (LFC), has been inserting into its research activities the use of CTBTO data to simulate various scenarios containing the dispersion of radionuclides in the atmosphere, thus predicting response and specific emergency actions. In this work, data inversion was performed to determine the amount of 137Cs released during the Fukushima Daichi nuclear accident, followed by a CFD simulation to analyze the behavior of the radioactive cloud at obstacles near the emission source, the dose received and the concentration level of 137Cs in the atmosphere.
Method for calibration of SPAD detectors using photon time of arrival statistics
Authors: Tavares VS , Costa Monteiro E , Temporão GP
Published: April 2021

Single-photon Avalanche Detectors (SPAD) are widely used in modern quantum optics experiments and applications. This work proposes an alternative method for calibrating SPADs by optical attenuation, based on the recognition of the statistical distribution of time intervals between consecutive detections.
Experimental-numerical approach to the estimation of uncertainty in robot pose measurement
Authors: Porath M C , Gross C F D , Eger J S
Published: April 2021

Accurate pose measurements are crucial for the reliability of the kinematic calibration and performance evaluation of a robotic manipulator. Spherical coordinate measurement systems such as laser trackers and total stations are commonly used to collect sets of 3D points from which position and orientation of a moving coordinate frame attached to the end-effector in relation to a reference coordinate frame are calculated. Estimating the uncertainty of this specific measurement task is necessary to provide traceability to these measurements. In this paper we propose combing measurements of calibrated artefacts with Monte Carlo simulations to estimate this task-specific measurement uncertainty. The application of this method has been demonstrated for the performance evaluation of a Stewart Platform using a robotic total station. Expanded uncertainties between 0.40 mm and 0.63 mm have been estimated for position. Expanded uncertainty was 0.10° for all orientation results.
A case study on electromagnetic field assessment and uncertainty evaluation
Authors: Travassos X L , Grubsic S , Porath M C , Souza Filho A L
Published: April 2021

This paper presents a radiofrequency electromagnetic field exposure assessment carried out in an observatory open for general public, where there are multiple radio and television transmitters in the surrounding area. An uncertainty evaluation is presented, considering that the main broadcast stations reduced their transmitted power to comply with the regulatory limits throughout the observatory area. A discussion is done about uncertainty of measurement result and its use or not in both precautionary measure and sanctioning process applied by regulatory authority.
Design of a current switching system for high accuracy current sources in AC-DC Transfer applications
Authors: Hernández Prada CF , Sáchica Avellaneda M , Martínez López A
Published: April 2021

A current switching system for AC-DC transfer applications using Single Junction Thermal Converters (SJTC) was designed and tested at Instituto Nacional de Metrología (INM). This switch design can directly commute between a DC reference current source and an unknown AC current source generated by high accuracy calibrators such as Fluke 5720A and Fluke 5730A. Two vacuum latch relays with an estimated switching speed of less than 10 ms were used. A control unit developed over a MSP430 Microcontroller allowed the switching control and serial communication with instruments through LabVIEW. It was found that, it takes between 2 s and 3 s for high accuracy calibrators to switch between an operating DC current and an AC current, or vice versa; therefore, the current commutation time is limited by the calibrator. By using two calibrators and the implemented current switching system it was possible to reduce the commutation time to about 300 ms, which is less than the reported SJTC thermal time constant. The switching system must be fast enough to avoid the calibrators to go to a standby state. The research work showed that the switching system could be used to improve thermal converters operation for the calibration of high accuracy AC current sources and multimeters.
Development of a voltage curve prediction model for lithium-ion battery based on destructive tests
Authors: Teixeira R. S. D. , Louzada D. R. , Gusmão L. A.P. , Calili R. F.
Published: April 2021

With the increasing development of portable devices, research on mobile power sources have been an important goal. Thus, the improvement on their safety, energy density and degradation rate is the current challenge of different researchers. The present work seeks to develop an algorithm, based on artificial neural networks, to predict the voltage curve of a lithium-ion battery based on destructive tests. It was found that the developed system can define the condition of the battery in the test and generates voltage curves that allow the estimation of the batterys charge and its charging time.
The application of modified polyetheleneterphthalate (pet) nanofibers; characterization and isotherm study
Authors: Ahmed H A , Saleem P H , Yasin S A , Saeed I A
Published: April 2021

In this study, dibenzo crown ether (DB18C6) is used to chemically modify the Electrospun Polyethylene Terephthalate (PET) nanofibers. The main parameters influence on the PET nanofiber’s surface modification with crown ether concentration and other solvents has been tested. The PET nanofibers with and without (DB18C6) are put into comparison by scrutinizing FTIR, TGA, SEM, and EDX results. It is to be mentioned that the modification of the PET nanofibers with crown ether is utilized for the extraction of methylene blue (MB) from aqueous solutions. For the purpose of evaluating the potential of the chemically modified PET nanofibers as adsorbents to remove MB from aqueous solutions, experiments of batch adsorption are carried out. The effect of MB concentration, solution pH, and shaking time are optimized. Several isotherm models such as Langmuir, Freundlich, Tempkin, and Dubinin - Radushkevich (D-R) equations are utilized to test the equilibrium results. Owing to the high correlation coefficient (R2), the adsorption of MB into the modified PET is detected through Langmuir model. ΔGo, ΔHo, and ΔSo quantities are estimated. The negative ΔG° values, the positive ΔHo, and ΔSo values indicate that the adsorption process is spontaneous and endothermic.
Synthesis and characterization of new compounds derived from 2-hydrazinobenzothiazole and evaluated their antibacterial activity
Authors: Khalil M I , Khalal Q Z
Published: April 2021

A series of new benzothiazole hydrazide derivatives starting from 2-mercaptobenzothiazole have been synthesized. 2-hydrazinobenzothiazole [M1] was prepared by refluxing of a mixture of hydrazine hydrate. H2O (80%) with 2-mercaptobenzothiazole. The reaction of the compound [M1] with the synthesized esters and amino esters [M2-M7 afforded benzothiazole hydrazide derivatives [M8-M13]. Compounds [M2-M7] were prepared from the reaction of different amino acids and carboxylic acids with absolute ethanol in presence of concentrated sulfuric acid. The structures of all synthesized compounds were established on the basis of FT-IR and some of them by 1H-NMR. The synthesized compounds have been evaluated for antimicrobial activity against Gram-positive and Gram-negative bacteria. Among thirteen synthesized compounds, in which four compounds (M8-M12) exhibited promising antibacterial activity.
Electrochemical study of Fe II/Fe III on modified GCE with PAN and PMMA at different temperatures using cyclic voltammetry
Authors: Ibrahim A I , Radhi M M
Published: April 2021

Poly (Methyl Methacrylate) (PMMA) was studied as a chemical compound used almost universally for teeth base manufacture. The study was focused on the effect of different temperatures of potassium ferricyanide K3[Fe(CN)6] in 1M KCl as an electrolyte using CV technique at modified glassy carbon electrode (GCE ) with poly-acrylonitrile (PAN) and PMMA as working electrode (PAN/PMMA/GCE). The thermodynamic functions such as activated enthalpy (ΔH*), free energy (ΔG*) and entropy (ΔS*) for redox current peaks of K3[Fe(CN)6] in 1M KCl on (PAN/PMMA/GCE) electrodes, using Eyring was explored. The determination of the activation energy (Ea*) determined by Arrhenius equations for the oxidation-reduction current peaks of K3[Fe(CN)6] to compare values obtained by K3[Fe(CN)6] in 1M KCl on various electrodes was studied.
Photodegradation of lauth’s violet dye using GO-Fe3O4-TiO2 nanocomposite under solar light
Authors: Hashim A , Al-Abodi E E
Published: April 2021

TFGO nanocomposite was synthesized from limited amounts of Titanium dioxide nanoparticles and Iron oxide nanoparticles as well as Graphene oxide nanosheets, by a situ method preparation. The producting materials were identify by (FTIR) and (AFM). The photocatalysis activity of TFGO nanocomposite was investigated by applying it in advanced oxidation processes (AOP) to degradation of Lauth’s violet or Thionine acetate (LV) dye under solar light. The photodegradation efficiency of LV dye could be gained 98% at existance of TFGO nanocomposite as photocatalyst within 320 min. Photocatalytic processes experiments were happen at different effects like temperatures and existence of light.
Comparison between nano zero valent iron supporting onto activated carbon collected via two types of reagents statistically: Carbon for cationic dye removal
Authors: Hammed A K , Al-Asfoor I K , Al-Dahan A K
Published: April 2021

One of the important substances was the carbon which was used to prepare adsorbents like, Nano zero-valent iron on carbon as supporting materials by sodium borohydride as a reducing agent. Nitric acid was used with heating at a temperature of 90 ° C and stirring for two hours to generate active groups on the surface of the activated carbon. The new zero-valent iron adsorbent was loaded on the surface of the functionalized activated carbon (NZVI/AC) and characterized using X-ray diffraction (XRD), the surface area measurement (SBET), and the Field emission scanning electron microscopy (FESEM). The synthesized (NZVI/AC) was applied for the removal of cationic dye as methylene blue (MB) from simulated wastewater. On the other hand, the adsorption and the kinetic studies for the MB removal were investigated via both kinetic models as the pseudo-first and the pseudo-second-order kinetic models. Also, the initial concentration of the MB adsorption studies was with a concentration of 20 mg/L, the adsorbent dosage of 0.1 g, the contact time of 60 minutes with high uptake value at natural pH solution. It was found that the removal efficiency of the adsorbent NZVI/AC was higher than the AC without Nanomaterial’s with values of 96.70% and 84.16% respectively. It is noted that the removal rate increased almost 12 times in comparison between AC and NZVI/AC. In the kinetic studies; the second-order kinetic model was more favorable than the first-order kinetic model in the adsorption mechanism. Thermodynamically, the Gibbs free energy (ΔG°) was found to be with a negative value indicating the spontaneity of the process, while the change in the entropy ΔS° and the enthalpy ΔH° with positive values indicating the adsorption of MB was an endothermic process. It could conclude that the new adsorbent NZVI/AC had significant potential for the cationic dye removal than the activated carbon AC in the environmental application.
Synthesis of some new organotellurium compounds based on 1-substituted tetrazole
Authors: Abbas S H , Al-Fregi A A , Al-Yaseen A A
Published: April 2021

New organotellurium compounds are derived from 1-butyl-5H-tetrazole (1). 1-butyl tetrazole-5-yl mercury (II) chloride (2) was synthesized from the reaction of compound 1 with mercury acetate and sodium chloride. The 1:1 and 1:2 ratio reactions of tellurium tetrabromide with compound 2 gave 1-butyl tetrazole-5-yl tellurium tribromide (3) and di (1-butyl tetrazole-5-yl) tellurium dibromide (4), respectively. The reduction of compounds 3 and 4 by the alcoholic solution of aqueous hydrazine gave di (1-butyl tetrazole-5-yl) ditelluride (5) and di (1-butyl tetrazole-5-yl) telluride (6), respectively. The reaction of compound 5 with iodine and thionyl chloride gave 1-butyl tetrazole-5-yl tellurium triiodide (7) and 1-butyl tetrazole-5-yl tellurium trichloride (8), respectively. The reaction of compound 6 with iodine and thionyl chloride gave di (1-butyl tetrazole-5-yl) tellurium diiodide (9) and di (1-butyl tetrazole-5-yl) tellurium dichloride (10), respectively. The prepared compounds were characterized and the molar conductivities proved that the compounds 2–3 and 7–10 behaved as electrolytes (1:1).
Synthesis of peptide derivative as bio adhesive
Authors: Al-Salami F MA , Al-Shuwaili R K
Published: April 2021

Bio adhesive material is a protein adhesive, which has recently been highlighted as an attractive biologically based and highly functional adhesive as a new chemo enzymatic synthesis of co polypeptide. The bio adhesive polymer was prepared by modification of pepsin structure with vinyl monomer such as maleic anhydride using ceric ammonium nitrate as an initiator, then the grafted copolymer was substituted with amino drugs. This design carries controlled delivery over an extended period of time due to its digesting nature. The new drug copolymer was investigated using common spectroscopy methods, such as FTIR, 1H-NMR and UV Spectroscopy. The physical properties for the prepared polymers were tested. Our results show that deprotonated is required for drug copolymers when analyzed in different pH values at 37 °C in vitro study and controlled drug release was compared at zero time and after three days. The rate of hydrolysis in basic medium was higher than acidic medium. It was concluded There are several advantages of sustain release by modified drug with slow release and in vivo performance was noted to be promising using for applications of polymer used different mice and rabbits infected with bacteria and wounds.
Extraction methods of Alhagi Maurorum (camel thorn) and its therapeutic applications
Authors: Urabee M C , Abdulsattar J O , Nasif Z N , Al-Garawi Z S
Published: April 2021

Alhagi maurorum (A. maurorum) is one of the medicinally important plants that belongs leguminasae family, commonly known as Camel thorn. This article we will present the methods of Alhagi maurorum plant extraction, the compounds of the extract and the compounds in the plant extract and its various therapeutic applications in the medical field and highlight the importance of plant extracts as alternatives to manufactured medicines with multiple side effects, the plant extracts has many compounds the most important is flavonoid and phenolic because of their therapeutic properties such as anti-oxidants and anti-inflammatory.
Characterization of some biochemical parameters in respiratory system diseases
Authors: Mosa M J , Alkazazz F F
Published: April 2021

This review article presents a general investigation about respiratory diseases starting with definition and classification also we are focus on the parameters which are useful to diagnose this disease, finally the treatment methods of all respiratory diseases were mentioned in. There are two common types of respiratory disease were expressed in detail with the define by physiological and biochemical causes of each diseases or illness. Chemical tests, biological investigations, and imagining techniques are three ways to diagnose the infection of respiratory system with multiple abilities to recognize between different diseases by all the diagnosis methods. Treatment of all types of respiratory diseases achieved by the elimination of inflammation by special drugs or by last therapeutic option the Lung transplant. Finally, we concluded there are several types of respiratory diseases differ from each other by many considerations and the diagnosis of respiratory diseases can be doing by biochemical and biological tests also we find the treatment of all types of respiratory diseases achieved by the elimination of inflammation or transplant the lung.
A review on autoimmune diseases Myasthenia Gravis: Causes, pathogenesis, symptoms and treatment
Authors: JarAllah S A , Al-Garawi Z S
Published: April 2021

Native and foreign microorganisms, such as viruses, bacteria, and parasites, are actively protected by the immune system. This defense can however be improperly misdirected against tissues and cells in some people, giving rise to autoimmunity and eventually autoimmune diseases. Autoimmune disorders are a wide variety of illnesses which can affect any part of the body, either localized (such as thyroiditis) or systemic to specific organs or tissues and affect several organs or tissues (such as systemic lupus erythematosus). As an example of autoimmune diseases that affect the voluntary muscles, myasthenia gravis (MG) is an autoimmune neuromuscular junction disease (NMJ) triggered by antibodies that target postsynaptic membrane components, impede neuromuscular transmission and contribute to skeletal muscle weakness and fatigue. Here is a review of the past and clinical aspects of MG to explain the mechanisms of AChR, MuSK and Lrp4 antibodies, the history and clinical aspects of MG are explored with an emphasis on the structure and role of myasthenic autoantigens at the NMJ and how they are influenced by the pathogenic mechanisms of the autoantibodies.
Investigation of the influence of the scanning speed and step in laser marking and engraving of aluminum
Authors: Balchev I , Atanasov A , Lengerov A , Lazov L
Published: April 2021

Marking and engraving of aluminum was carried out by a CuBr (copper bromide) laser operating at the wavelength of 511 nm with a pulse duration of 30 ns. The reflection was investigated of the laser-ablated aluminum surface depending on the laser beam scanning speed and the distance between the laser lines. The changes of the aluminum surface were observed before and after laser processing by an optical microscope and visually. The laser marking quality was estimated by measuring the reflection of the irradiated aluminum surface by an optical spectrometer. The dependence was analyzed of the contrast on the speed for different steps in laser marking of areas of the surface of aluminum samples. Marking by a CuBr laser shows a potential for good quality marking of barcodes and QR codes on aluminum products.
Modelling of the diffraction efficiency of surface relief gratings with varying spatial frequency, height and shape of the relief
Authors: Blagoeva B , Berberova N , Nazarova D , Nedelchev L , Mateev G , Stoykova E , Otsetova-Dudin E , Sharlandjiev P
Published: April 2021

An important goal in the development of diffractive optical elements is to achieve high diffraction efficiency. One class of these elements are the surface relief gratings recorded by polarization holography. For recording media, we used azopolymer (poly[1-[4-(3-carboxy-4-hydroxyphenylazo) benzenesulfonamido]-1,2-ethanediyl, sodium salt]), shortly denoted as PAZO. The aim of the present work is to simulate a highly efficient surface relief grating formed in the azopolymer PAZO. The model is based on experimental results already obtained by our group. The tasks of the research are related to the analysis of the diffraction efficiency in the spectral range from 300 nm to 800 nm and for: 1) range of grating spatial frequencies from 1200 ln/mm to 1800 ln/mm, 2) surface relief height varying from 100 nm to 400 nm and 3) different shapes of the formed relief.
Nd:YAG laser ablation of micro-crystalline graphite in a water suspension
Authors: Milenov T , Dimov D , Nikolov A , Stankova N , Avramova I , Avdeev G , Russev S , Karashanova D , Georgieva B , Kostadinov I , Karaivanova D , Kolev S , Valcheva E
Published: April 2021

The aim of this work was to obtain graphene-like phases (defected graphene, graphene oxide and reduced graphene oxide) as fine suspensions by applying pulsed laser ablation (PLA) of micro-crystalline graphite suspension in water medium. The fundamental (λ = 1064 nm), second (λ = 532 nm), third (λ = 355 nm) and fourth harmonics (λ = 266 nm) of a Nd:YAG laser system (15-ns pulse duration and 10-Hz pulse repetition rate) were used. The morphology of the particles was studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Their phase composition and structure were explored by Raman and X-ray photoelectron spectroscopies, grazing incidence X-ray diffractometry (GIXRD) and TEM. The specimens were prepared by drop-casting on a glass substrate (for Raman and GIXRD studies) and on a standard TEM copper mesh for SEM and TEM examination.
Finite element modeling of laser aluminum marking
Authors: Lazov L , Angelov N , Draganov I , Atanasov A , Lengerov A , Teirumnieks E , Balchev I
Published: April 2021

This work makes use of the finite element model, whose results are validated by experiments. The effect is discussed of the speed on the laser marking process. Numerical experiments are performed to determine the temperature fields produced by laser pulses on samples of aluminum, a material with wide industrial uses. The numerical calculations are performed for the cases of a fiber laser and a CuBr laser. Plots are drawn of the temperature dependence on the speed for two power densities for both lasers. Preliminary working speed intervals are determined for the power densities used.
Nonlinear enhanced-absorption resonances in compact alkali-vapor cells for applications in quantum metrology
Authors: Brazhnikov D V , Ignatovich S M , Mesenzova I S , Mikhailov A M , Skvortsov M N , Goncharov A N , Entin V M , Ryabtsev I I , Boudot R , Taskova E , Alipieva E , Andreeva C , Gateva S
Published: April 2021

We review three laser spectroscopy schemes developed recently for observation of high-contrast enhanced-absorption nonlinear resonances in small alkali-vapor cells. In our experiments, optical transitions within the cesium D1 line are involved and a probe beam transmission is analyzed. The first spectroscopy method is based on the configuration with two-frequency counter propagating beams, which are linearly polarized in orthogonal directions. This configuration provides observation of high-contrast natural-linewidth resonances superimposed on broad Doppler profiles when the laser frequency is scanned. These resonances have good prospects for developing a miniature optical frequency reference. The second scheme involves two-frequency counter propagating beams with equal circular polarizations and provides observation of subnatural-linewidth resonances when the Raman frequency detuning is scanned. We use these resonances for stabilizing the microwave frequency of a local oscillator (≈ 4.6 GHz). Frequency stability of around 6 × l0-12 is achieved at 1-s averaging using a 5-mm length cell. This result makes the technique attractive for developing a miniature frequency standard in thr microwave range. The third configuration exploits single-frequency counter-propagating beams with linear orthogonal polarizations. The ultrahigh-contrast subnatural-linewidth resonances can be observed when the longitudinal magnetic field is scanned around zero. The possible application is discussed of these resonances in vector atomic magnetometry.
Estimation of the double-scattering component of the lidar return from multi-component atmosphere
Authors: Evgenieva Ts , Grigorov V , Anguelov V , Gurdev L
Published: April 2021

Estimation is performed based on a theory developed by Eloranta of the double-scattering contribution to the LIDAR return from a multi-component atmosphere that may contain not only molecular (gaseous) and aerosol fractions, but other compact aerosol objects as well, such as cirrus clouds or Saharan dust layers. It is shown that the relative double-scattering component of the LIDAR return may be approximately considered as a sum of the independent relative contributions of each of the atmospheric components. Then, using appropriate models, the contribution of each component of interest is evaluated as a function of the altitude, taking into account the scattering properties of the medium under consideration, the angular divergence and the wavelength of the sensing laser beam, and the angle of view of the receiving optical system. The results obtained outline the cases when either the double scattering is negligible or corrections are necessary for the multiple scattering effects.
Lidar observations of massive Saharan dust intrusion above Sofia, Bulgaria, in April 2019
Authors: Peshev Z Y , Deleva A D , Vulkova L A , Dreischuh T N
Published: April 2021

A large-scale massive transport of Saharan dust over all of Europe was observed in the last third of April 2019. As part of the European Aerosol Research Lidar Network (EARLINET) and the Aerosol, Clouds and Trace Gases Research Infrastructure (ACTRIS), Sofia lidar station conducted lidar observations of the atmospheric aerosol load in this period. Some of the results obtained are described in this work. Remote measurements were implemented using two elastic-scatter lidar channels (1064 nm/532 nm). The paper presents results of studying and analyzing the optical and microphysical properties of the aerosols detected, as well as the topological and dynamical features of the aerosol/dust layers observed. The height profiles of the atmospheric aerosol backscattering coefficient are retrieved and discussed. The microphysical properties of aerosol/dust particles are characterized qualitatively based on an analysis of the backscatter-related Ångström exponents profiles and distributions obtained for particular aerosol layers. Dust mixing with other aerosol types of local origin or such captured during the transport is also considered and discussed based on local meteorological radiosonde data and air-transport modeling and forecasting data. Conclusions are drawn concerning the experimentally ascertained and the possible impacts of the massive dust intrusion event on the local tropospheric aerosol structure and meteorological conditions.