bluuebunny/crossref_metadata_2025 huggingface dataset:
Social Profit of Legal Metrology in the Brazilian Electricity Sector
Authors: Rodrigo Otávio Ozanan , Sérgio Ballerini , Araujo Alves Henrique , Costa-Félix  , Rodrigo
Published: April 2021

In Brazil, despite of the undeniable importance of metrology in society, there is still no consensus as to the most effective way to “quantify” this statement. The aims of this study is to present a method to quantify the social impact caused by legal metrological control, focusing on voluntary verification and legal metrology expertise in electrical energy meter . In this sense, this article presents a model, developed exclusively for the public sector, with the objective of quantifying the return or economy in favor of society through National Legal Metrology System direct and indirect actions in the Brazilian electricity sector, considering the 2017 year. This model is an adaptation of Social Profit mode the “Brazilian Agricultural Research Corporation – Embrapa”. . Only laboratories under the control of the Legal Metrology Board, through their delegated bodies, which perform or supervise voluntary checks and metrological examinations performed by the technicians of the Brazilian Network of Legal Metrology and Quality – RBMLQ, were considered. Next step, performance indicators were proposed and validated to obtain social profit. The data show that Inmetro’s actions enable a return to society of US$ 32 million for each US$ 1 million of investment in this activity, pointing to the effectiveness of the model in quantifying the social profit of the agency. In a more detailed analysis it was possible to evaluate a potential revenue recovery for the states, throughTaxes, of the order of US$ 400 million, if the actions of expertise and verification are intensified, pointing to a promising horizon of revenue increase for the Brazilian government through the fight against fraud. Preliminary analyzes show both the massive presence and extreme remoteness of the state are not the best management models to be adopted for the electricity sector. The study suggests, at first, a direct correlation of Inmetro intervention and participation actions in partnership with the private sector in the electricity sector and revenue recovery with reduction in the increase of electric bills. Thus, we infer that the presence of the state as regulator in this case can be effective if adapted to reality. Further studies, however, need to be done. Social profit proved to be effective for use in actions to improve public governance, another point to be explored further on.
Predicted standard deviation of proficiency testing performance in animal nutrition methods
Authors: Souza Gilberto Batista de , Nogueira Ana Rita de Araujo
Published: April 2021

The empirical correlations of the results of over ten years of a proficiency testing of animal nutritional analysis conducted by Embrapa were evaluated. The results demonstrate the similarity of the Horwitz equation proposal, but it is desirable to use individual equations related to the different analyses performed by the laboratories. Using these equations enables a more realistic assessment of possible systematic errors and analytical processes, improving laboratory performance and providing the most reliable results.
An irradiation system for evaluating individual electronic dosimeters in pulsed x-ray beams
Authors: Guimarães Margarete C , Dias Fábio S , Da Silva Teógenes A
Published: April 2021

Electronic dosimeters are widely used for individual monitoring, especially for direct dose equivalent assessment associated with a specific task. Most of x-ray beams used in diagnostic radiology have been considered as pulsed one due to their high intensity during a very short time. This work showed that a Rhos Vari X x-ray machine was feasible to be used to evaluate electronic dosimeters in high pulsed air kerma rates to detect deficiencies in their response. In comparison to continuous x-ray beams, it was observed that personal dose equivalent values were severely underestimated by some electronic dosimeters in pulsed radiation fields.
A study to elaborate a technical manual of veterinary radioprotection
Authors: Sousa CHS , Nascimento ET , Padilha LG , Araújo GS , Peixoto JGP
Published: April 2021

ANVISA Ordinance 453/98 reports the importance of radiological protection, in its fundamental principles, for the protection of patients, workers and the public in the medical and dental radiology sector. However, health surveillance has failed to control veterinary medical radiodiagnosis. Due to the peculiarity of working with animals, the veterinarian has been overexposed to ionizing radiation. This work is quantitative and observational carried out with some clinics, veterinary radiologists and data from personal files, internet and literature. Thirty people were included in the study, where 60% assumed the position of technical manager, 66.7% the radiological protection supervisor, 13% have updated radioprotection training, 66.7% do not carry out quality tests and maintenance of equipment and 76.7% have doubts about radioprotection standards. It was found that a significant proportion of veterinary radiologists are unaware of radioprotection standards, or have doubts about the matter, exposing themselves unnecessarily to ionizing radiation putting their health and that of others at risk
Self-calibration of the secondary laser source in two-color Linnik interferometer
Authors: Malinovski I , França R S , Couceiro I B
Published: April 2021

The imaging Linnik interferometer equipped with two lasers of different colors is under development and metrological study at National Metrology Institute of Brazil (INMETRO). This work reports the self-referenced method for practical calibration of the secondary laser wavelength. The method is based on accurate digitalization and comparison of the waveforms for both reference He-Ne stabilized laser at 633 nm and secondary laser diode at 488 nm. The process makes use of multiple step phase-shifting technique for waveform measurement and multi-parameter fit for wavelength extraction. The advantage of the method is that no extra hardware of realignment of interferometer is required to perform the calibration.
A procedure for assessing geometrical accuracy of selective laser melting processes with standard parts
Authors: Simão I T , Porath M C , Beckert S F
Published: April 2021

The assessment of the geometrical accuracy of an additive manufacturing process is crucial to evaluate its capability to produce parts within specification limits. A standardized procedure for the accuracy evaluation of SLM processes with standard parts is proposed. The procedure includes recommendations for manufacturing, measurement and statistical evaluation. Process repeatability and bias are defined as characteristic accuracy indices. A case study was carried out in which two systems were compared. Repeatability was similar for both systems. Not negligible bias was detected but there was no evidence of significant difference between biases of both systems.
Development of a virtual balance for didactic purposes applied to mass metrology
Authors: Quintão D
Published: April 2021

Inmetro provides technical training in mass metrology area, it seeks to increase the number of hours of hands-on activities. Virtual resources to simulate practices may be used. The objective of this work is to develop a virtual balance that works on a PC and simulates real equipment’s behavior. It has been obtained an indication mathematical model of a real balance through study of physical parameters that influence on weighing and it has been programmed this mathematical model in Virtual Balance Graphical Interface. Mathematical model was validated by comparing Virtual Balance weighing results and experimental results obtained using a real balance.
Industrial Dynamic Measurements of Mechanical Quantities within the Inter-American Metrology System (SIM)
Authors: Savarin Alejandro , Serrano Federico , Pineda Guillermo Silva , Guzman Jorge Torres , Prieto Juan Alberto Arias , Pulido Ivan David Betancur , Chijioke Akobuije , Vlajic Nick , Machado Renato Reis , Oliveira Rafael Soares de
Published: April 2021

Most industrial measurements of force and torque are performed dynamically, while calibrations are performed mostly in static form. It is evident that the dynamic responses of the instruments are very different from the static form. The National Metrology Institutes (NMIs) have been requested by industry to develop solutions for this gap in metrological traceability and have recently undertaken activities to do so. The Inter-American Metrology System (SIM) implemented the project “Industrial Dynamic Measurements (from industry to primary standard)”, involving the NMIs: INTI/Argentina, INMETRO/Brazil, NIST/USA

CENAM/Mexico and INM/Colombia. Main backgrounds, findings and outlooks of the project are highlighted in this paper.
Construction and evaluation of a low-cost AC-DC current shunt
Authors: Pinto M V V , Ventura R V F , Pontes R R , Costa L V S , Souza L A A
Published: April 2021

The process of construction and evaluation of a shunt prototype for AC-DC transfer produced by Inmetro, built with low-cost materials and using commercially available thin film chip resistors will be presented. The main objective of this work is fully achieved, obtaining an equipment with characteristics that allow its use as standard in the calibration of AC current sources of high accuracy, in a wide frequency range.
Precision electrical power sources calibration using electrical energy and frequency standards
Authors: Costa Marcelo Melo da
Published: April 2021

This paper presents an alternative method for precision electrical power sources calibration. As traditional method, the proposed method uses a power and energy standard, but also employs a frequency standard. Calibration results for both methods are discussed and their advantages are pointed out.
Clinical studies about the influence of calcium intake on the biochemical parameters of bone metabolism
Authors: Rasheed N W , Ahmad R I
Published: April 2021

Calcium is a major component of bone, an adequate dietary supply of calcium during growth being considered critically important for the development of strong and healthy bone. The aim of the study was to evaluate the short term effects of dietary calcium intake on the biochemical diagnostic of the hyperparathyroidism in healthy people Subjects. The study was conducted on 36 subjects (age between 21 and 71 years, 4 men and 32 women) recruited from patients refereed to the Endocrinology Department of Elias Hospital who were not diagnosed with diseases proved to influence calcium or bone metabolism and agreed with the study for inclusion in the study, all subjects were checked for thyroid dysfunctions, hypercortisolism, hypogonadism, and active liver diseases which might interfere with total alkaline phosphatase values. The data obtained through this study sustain the significant effect of short term variations in calcium dietary intake on the biochemical diagnosis of hyperparathyroidism.
The mechanism of leptin and IGF-1 in the diabetic rheumatoid arthritis Iraqi patients
Authors: Al-Garawi Z S , Tahir N T , Tabatabai Z M A , Salman A T
Published: April 2021

We aimed here to study the impact of leptin on insulin like growth factor-1 (IGF-1) level to imply its antidiabetic effect on Iraqi rheumatoid arthritis’s, who was with and without diabetes mellitus.

Rheumatoid arthritis is a chronic inflammatory disease, primarily targets the synovium and articular cartilage, which causes joint damage. Although the role of adipocytokines in mediating damages of joint has recently suggested, it is still a matter of considerable debate.

METHODS: Patients diagnosed as diabetic rheumatoid arthritis aged from 33-60 years and others diagnosed as non-diabetic rheumatoid arthritis were compared with healthy control (aged 33-46 years). Some biochemical parameters have determined, such as fasting serum glucose, glycated hemoglobin, lipid profile, serum fasting insulin, IGF-1, and leptin, using ELISA and immune radiometric assay. Results indicated an elevation in some biochemical parameters in diabetic rheumatoid arthritis’s when compared with patients without diabetes. There was a significant increase in fasting serum glucose and some of the lipid components in diabetic rheumatoid arthritis patients compared to that non-diabetic. A significant elevation of leptin in diabetic rheumatoid arthritis patients compared to control (p<0.003). However, a non-significant difference of leptin was detected between diabetic rheumatoid arthritis and non-diabetic patients. In addition, some other parameters were significantly reduced in diabetic rheumatoid arthritis patients when compared to non-diabetic patients, such as high-density lipoprotein and IGF-1. This study highlights that leptin could act as pro-inflammatory mediator in rheumatoid arthritis. The negative correlation between leptin level and IGF-1 plays an important role in understanding the metabolic pathogenesis of rheumatoid arthritis.
The potential of Azolla filiculoides for in vitro phytoremediation of wastewater
Authors: Rezooqi A M , Mouhamad R S , Jasim K A
Published: April 2021

This study was conducted to apply phytoremediation technology in removing pollutants from wastewater to reuse it for different purposes; this technology is considered one of the promising technologies, as it is environmentally friendly, cost-effective, and removing pollutants. The experiment was conducted in the Al-Tuwaitha location (Iraqi Atomic Energy Agency, IAEA). Six glass tubs of (30×30×30) cm dimension and 27 L capacity each were filled with sewage water that brought from Al-Rustomia sewage plant after primary treatment stage bowl, 100g of Azolla plant which brought from Al-Chibayish Marsh in the south of Iraq were placed in three tubs and the other three was without plants (control) after 28 days the plants were harvested. Many pollutants and nutrients were determined every week. The results showed that the percentage of (SO4, Cl, PO4, NO3, COD, BOD, Ec) removing was (56, 52, 55, 52, 46, 42.5, 23) % respectively at the first fourteen days, and at 2nd fourteen days was (83, 76, 84, 76, 79, 63, 49) % respectively.
The effect of pituitary hormones levels and relationship to female infertility in Baghdad province
Authors: Nasser A M , Al-Jumaili E F , Alhusni Z K
Published: April 2021

This study carried out to investigate the relationship between prolactin, LH, FSH, TSH hormones and female infertility. The results demonstrated high significant of prolactin (P<0.01) between infertile women as contrasted with an intact group. The outcomes additionally indicated a significant difference at (P<0.01) of TSH of infertile women as contrasted and unblemished and demonstrated a significant difference at (P<0.05) of infertile women as contrasted and with intact. There were no significant differences of (FSH) level between infertile women and intact. The investigation shows the part of prolactin hormone was the most impact of the female infertility.
Osmotic fragility in essential hypertension revisited: A correlation with Iron status and lipid profile
Authors: Alhillawi Z H , Al-Ani S R M , Al-Hakeim H K
Published: April 2021

Essential hypertension is a major public health associated with increased pressure on the vascular walls and red blood cells (RBCs). In the present work, osmotic fragility (OSF) of RBCs was reexamined in the measure of its correlation with two risk factors; iron status and lipid profile. OSF, iron status parameters, and lipid profile components were measured in eighty-eight patients and compared to the results of thirty controls. The results presented a significant increase in all iron indices of hypertensive patients compared to the normotensive group excluding transferrin concentrations and UIBC decreasing in these patients compared to the healthy group. Serum TGs, total cholesterol, VLDLc, and LDLc increased in patients as compared with control group. There is no significant change in OSF between patients and controls. The iron status parameters and LDLc and TG components were dependent on sex and smoking state. Hemoglobin and PCV were correlated significantly with total cholesterol and LDLc. Transferrin saturation showed a positive correlation with cholesterol, LDLc, and TGs, but negatively correlated with HDLc. No significant correlation between all the measured parameters and OSF in patients with HT. There is a significant correlation between serum ferritin and systolic BP and between Hb and systolic BP. Conclusion. Hypertension as a mechanical challenge for RBCs membrane has no significant effect on the OSF in hypertensive patients. Iron status parameters showed an elevation in HT patients as compared with controls. OSF has no significant correlation with iron status parameters or with lipid profile components in HT patients.
Vitamin D deficiency is associated with thyroid diseases
Authors: Jubair S , Nsaif A S , Abdullah A H , Dhefer I H
Published: April 2021

Background The deficiency of vitamin D3 (VD) is a universal health issue, its role in different kind of diseases is being studied recently. However, its role in thyroid diseases is not well established yet. This study aims to determine the impact of VD in the pathogenesis of hypothyroidism and hyperthyroidism. Method. Three hundred Iraqi females with age ranged between 30 and 55 years participate in this research, 100 of them were hypothyroid patients, 100 females were hyperthyroid patients and the other 100 females were healthy volunteers served as controls. Thyroid hormones, VD, liver function parameters, and kidney function parameters were determined using different analysis techniques. Results. The levels of VD were significantly decreased in both hypothyroid and hyperthyroid patients (19.644 ± 10.524 for hypothyroid patients and 22.712 ± 11.249 for hyperthyroid patients vs. 30.880 ± 2.587 for controls, p <0.0001). Liver function parameters were within the normal ranges in all the patients. Creatinine and uric acid were within the normal ranges, while urea was significantly increased and out of the normal clinical range in both hypothyroid and hyperthyroid patients (39.560 ± 9.912 for hypothyroidism patients and 42.460 ±7.171 for hyperthyroid patients vs. 26.920 ± 5.033 for controls, p <0.0001). Conclusion. Vitamin D3 and kidney function tests must be included in the differential detection of thyroid diseases. Still, further investigations are needed to understand the underlying mechanism by which VD affects thyroid hormone regulation.
Determination of some biochemical parameters in sera of normotensive and hypertensive obese female in Baghdad
Authors: Taay Y M , Mohammed M T , Abbas R , Ayad A , Mahdi M A
Published: April 2021

Obesity is a disease describe a case of excessive accumulation of body fats. Obesity is linked to the morbidity of human health, such as the development of hypertension. The study designed to investigate the levels of glucose, urea, creatinine, and lipid profile parameters in sera of obese female and hypertensive obese female. The study included 90 subjects who divided onto three groups equally, in which they are healthy control, normotensive obese, and hypertensive obese. A significant elevation (P<0.01) has observed in the level of glucose, urea, creatinine, triglycerides (TGs), cholesterol, LDL-C, and VLDL-C in obese females compared with control, yet only TGs and VLDL-C were significantly differ in hypertensive obese from normotensive obese. On the other hand the level of HDL-C was significantly decreased in obese female compared with control. The elevation of TGs and VLDL in hypertensive obese female indicates their role in the complications of hypertension during obesity.
Synthesis and in vitro assay of 1-[5-(4-chloro-phenyl)-[1,3,4]thiadiazol-2-yl] derivatives as new antimicrobial agents
Authors: Ayrim N B , Abdula A M , Baker S M , Mohsen G L , Rodhan W F , Rasheed A H
Published: April 2021

A new series of 2,5-disubstituted-1,3,4-thiadiazole derivatives (1-8) was synthesized from the 5-(4-Chloro-phenyl)-[1,3,4]thiadiazol-2-ylamine. The reaction of the starting material with isocyanate and isothiocyanate derivatives afforded 1,3,4-thiadiazole containing urea and thiourea derivatives (1-3), respectively. Reaction of 1,3,4-thiadiazole with p-nitrobenzaldehyde produced new Schiff base 4. It cyclized thiazolidin-4-one (5) and azetidin-2-one (6) derivatives by the action of thioglycolic acid and chloroacetyl chloride. Compound 7 was synthesized by a reaction of 1,3,4-Thiadiazole with chloroacetyl chloride. Cyclization of compound 7 with ammonium thiocyanate produced compound 8. The Synthesized derivatives were characterized using spectral analysis. All the derivatives were In vitro screened against Escherichia coli, Klebsiella SPP (gram negative), Staphylococcus aureus, Streptococcus SPP (gram positive) and also Candida albicans and showed moderate to effective inhibition activity.
Role of antioxidant and oxidative stress levels in multiple sclerosis Iraqi patients
Authors: Muhammed O M , Al-Rubae’i S H N
Published: April 2021

Multiple Sclerosis is a multifactorial disease characterized by demyelination and inflammation of the central nervous system. Accumulating data indicate that changes in the balance of antioxidants and oxidants contributed to the MS pathophysiology. The aim of the study to obtain a better understanding of the oxidative stress process to select a proper method of predicting the prognosis of the relapsing-remitting MS (RRMS). Serum of 97 patients (30 newly diagnosed RRMS patients and 67 RRMS patients underwent treatment) and 35 healthy individuals as control group. Serum levels of 25-hydroxycholecalciferol [25(OH)D3], vitamin E, vitamin C, malondialdehyde, protein carbonyl, and 8-hydroxydeoxyguanosine. There was a negative correlation between MDA and antioxidant (vitamin C and vitamin E), whereas a positive correlation between MDA and other oxidative stress (PC and 8-OHdG). Receiver operator characteristic analysis showed that PC was an ideal marker while vitamin C, MDA, 8-OHdG were excellent markers. Our data showed that the above markers as a mean could be used to predict MS disease and the extent of its progression.
Laser removal of marker tags from a contemporary graffiti painting
Authors: Atanassova V , Ghervase L , Cortea I M
Published: April 2021

This contribution presents a study on the efficiency of the laser removal of black permanent marker tags from a contemporary graffiti painting. The effect of two wavelengths – 1064 nm and 532 nm, on the marker inks and the graffiti paints was investigated using optical microscopy and colorimetric measurements. Preliminary characterization of the marker inks and the paints by FTIR and XRF analyses was also performed. The results confirm that the materials’ response to laser radiation depends on their particular chemical composition.
A parametric study of sub-picosecond laser ablation of thin metal foils
Authors: Garasz K , Kocik M
Published: April 2021

With the properties of ultrashort pulse width and ultrahigh peak power, femtosecond lasers excel at processing materials whose thickness is less than 500 μm. Numerous experiments and theoretical analyses have testified to the fact that there are solid grounds for the future applications of femtosecond laser micromachining [1, 2]. However, with the high costs and complexity of these devices, it is the sub-picosecond laser that might be an alternative when it comes to micromachining of thin metal foils. Furthermore, investigating the sub-picosecond laser interactions with matter could provide a better understanding of the ablation mechanisms and experimental verification of existing models concerning the ultrashort pulse regime. We present research on sub-picosecond laser interaction with metal foils with a thickness of less than 250 μm under various laser pulse parameters. The research was conducted by two types of ultrafast lasers: a lab-designed sub-picosecond Yb:KYW laser (650 fs) and a commercial femtosecond Ti:S laser (35 fs). The results show how variables, such as pulse duration, energy, repetition rate, wavelength and irradiation time, affect the micromachining process.
Photoinduced chirality in azopolymer-based nanocomposites with different TiO2 nanoparticles concentrations
Authors: Mateev G , Nedelchev L , Nazarova D , Blagoeva B , Berberova-Buhova N , Stoykova E
Published: April 2021

After its discovery, photoinduced chirality in azopolymer materials has been studied with growing interest because of its potential applications. According to our previous investigations, it is possible to induce chirality in an amorphous azopolymer with a high linear photoanisotropy by illumination with elliptically polarized light. In the present work, we studied the photoinduced chirality in thin nanocomposite films based on the azopolymer poly[1-[4-(3-carboxy-4-hydroxyphenylazo)benzenesulfonamido]-1,2-ethanediyl, sodium salt], shortly PAZO, doped with TiO2 nanoparticles with a size of about 20 nm. The thickness of the prepared films was approximately 550 nm and the concentration of the nanoparticles varied from 0 to 3 wt. %. A He-Cd laser beam (λ = 442 nm) was used, with the input ellipticity varying from –1 (left circularly polarized) to +1 (right circularly polarized). The ellipticity was set using a quarter-wave and a half-wave plates. We studied the dependences of the output ellipticity and the angle of self-rotation of the polarization azimuth on the input ellipticity. Based on the experimental data obtained, we could analyze the dependence of the self-rotation of the polarization azimuth on the concentration of the nanoparticles. The results show that small concentrations of nanoparticles lead to an enhancement of the self-rotation, hence, the chirality.
Fabrication of aqueous colloids of TixO2x-1 and Ag composite nanostructures by means of pulsed laser processing
Authors: Stankova N E , Nikolov A , Karashanova D , Nedyalkov N , Dikovska A , Milenov T , Ristoscu C , Badiceanu M , Mihailescu I N
Published: April 2021

Pulsed laser ablation in liquids is utilized for preparation of composite nanostructures on the basis of TixO2x-1 and Ag. Plates of bulk Ti and Ag immersed in the corresponding liquid serve as targets in the ablation procedure. A nanosecond Nd:YAG pulsed laser is employed as a source of irradiation. Its fundamental wavelength and the third and fourths harmonic are used both to fabricate and to change the chemical composition and the morphology of the nanostructures considered. The procedure for synthesis of complex nanostructures is performed following a specific sequence, namely, the consecutive laser ablation of the selected targets is followed by a post-ablation irradiation of the colloid obtained of the complex nanostructures. The changes in the characteristics of the complex nanostructures are indirectly evaluated based on the profile of the optical transmission spectra of the as-obtained colloids. The colloids’ properties are controlled by varying the laser beam parameters. Transmission electron microscopy (TEM) is applied for direct visualization of their shape. The chemical composition and the morphology were assessed by high-resolution TEM and SAED analyses.
Coherent magneto-optical resonances in hot potassium vapor
Authors: Gateva S , Tsvetkov S , Todorov G , Gozzini S , Nasyrov K , Andreeva C , Cartaleva S
Published: April 2021

In this communication, we present experimental results on the preparation of magneto-optical resonances in potassium. The magneto-optical resonances are registered in Hanle configuration, i.e. monitoring the atomic fluorescence vs the applied magnetic field scanned around zero value. The excitation of the second resonance line with a wavelength of 404.4 nm leads both to direct fluorescence at 404.4 nm and to a cascade decay with fluorescence at 770.1 nm and 764.5 nm (first resonance line transitions). This transfer is evidenced by the registration of a narrow magneto-optical resonance in the fluorescence. It should also be noted that even after multiple cascade transitions, the resonance observed on the infrared lines has a much better signal/noise ratio compared to that on the excited second resonance line. Therefore, the study of these sub-Doppler-width magneto-optical resonances in hot potassium vapor will be useful for the further development of high-resolution magneto-optical laser spectroscopy.
Super resolution far field infrared microscopy
Authors: Hendaoui N , Korobchevskaya K , Bianchini P , Lamard L , Kellou A , Peremans A
Published: April 2021

We present and compare the performances of label-free super-resolution infrared microscopy based on non-linear properties intrinsic to all vibrational transition in three configurations such as pump-probe, differential absorption, and attenuated total reflection configurations. We then highlight experimental demonstrations achieved in label-free super-resolution chemical imaging that succeed in exploiting this novel concept.
Modeling and analysis of the RI sensitivity of plasmonic sensor based on MIM waveguide-coupled structure
Authors: Zegaar I , Hocini A , Ben salah H
Published: April 2021

In this paper, a plasmonic sensor is proposed based on a metal-insulator-metal waveguide coupled with a double-triangle resonator. The sensing structure is numerically and theoretically investigated using the two-dimensional finite difference time domain (FDTD) method. The results show the presence of a linear relationship between the materials refractive indices and the sensor’s wavelength resonances. The proposed structure revealed a high sensitivity value, reaching the maximum value for mode 1 S
mode1 = 1374 nm/RIU, and for mode 2 S
mode2 = 2365 nm/RIU. The proposed sensor can be classified as a high-performance nano-sensor that can be used to identify different materials.
Spring-to-summer observations of the aerosol load over Sofia-city using near-horizontal lidar sensing
Authors: Dreischuh T , Kolarov G , Grigorov I , Peshev Z , Deleva A , Vulkova L , Gurdev L , Stoyanov D
Published: April 2021

Using lidar and contact facilities, the relation is investigated experimentally between the extinction coefficient and the mass concentration of near-ground aerosol pollution over some districts in Sofia City. The extinction coefficient profiles of the aerosol ensembles along the lidar line of sight (LOS) are measured at the lidar wavelengths of 510.6 nm (CuBr-vapor laser source) and 1064 nm and 532 nm (Nd:YAG laser source). The particulate mass concentration is determined using data obtained concurrently by air-quality measuring sensors close to the LOS. Thus, the results obtained of the aerosol mass concentration-to-extinction calibration constant of the lidar concern mainly the sites around the nearest stations. To help the interpretation of the results, the accompanying weather conditions are also described. The experiments are conducted in the spring and the summer and the results obtained reflect the ecological peculiarities of the corresponding city regions of interest. The values found of the calibration constant are consistent with those obtained earlier in the same seasons.
Advanced portable DIAL hygrometer using high-power pulsed laser diodes with fiber-optical cascade collimator
Authors: Penchev S , Pencheva V , Dreischuh T
Published: April 2021

The DIAL hygrometer described integrates independent optical channels of high-power broad-line laser diodes of different wavelengths. A cascade collimator is developed based on tapered optical fibers of decreasing apertures, which ensures a minimal divergence of the laser beam for maximal discrimination of the background light. Effective twenty-four-hour DIAL profiling of humidity along a path of up to 3 km at a resolution of 2 gm-3 is targeted.
Lidar detection and characterization of multi-type aerosol layers in the troposphere above Sofia, Bulgaria
Authors: Deleva A , Peshev Z , Dreischuh T , Vulkova L
Published: April 2021

Aerosols can directly and strongly affect the atmospheric energy budget, the climatic processes, the ecological state of the environment, and the biosphere and human health. This is why the detection and identification of aerosols in terms of type and origin and their optical and microphysical characterization are of great scientific and practical importance. Lidars are a widely recognized and proven tool for detecting and studying atmospheric aerosols. In this paper, we present results of lidar detection and characterization of aerosol layers present in the troposphere over the city of Sofia. The measurements were performed at the wavelengths of 1064 nm and 532 nm by using the Nd:YAG-laser based lidar of Sofia lidar station, part of the European Aerosol Research Lidar Network (EARLINET) and the Aerosol, Clouds and Trace Gases Research Infrastructure (ACTRIS). Time-averaged vertical profiles of the aerosol backscatter coefficient and the backscatter-related Ångström exponent were retrieved and analyzed. Color-coded height-time diagrams of the vertical mass distribution in the observed layers and its temporal dynamics were also obtained. Based on information from forecast models, it is concluded that the aerosol layers registered contained marine aerosols, forest fire smoke, indirectly and directly transported dust from Sahara, as well as continental, regional and local aerosols from different sources.
Structural characterization of collagen using polarization-resolved second harmonic generation (SHG) microscopy
Authors: Mazumder N , Sindhoora K M , Kao F-J
Published: April 2021

Second harmonic generation (SHG) microscopy is an effective analytical tool for a detailed investigation of the microscopic structure of non-centrosymmetric molecules. We developed a four-channel photon-counting-based Stokes polarimeter integrated to the SHG microscope for spatial characterization of polarization effects in the SH signal. We implemented Stokes-vector-based polarization-resolved SHG imaging to perform quantitative polarimetry, with a view to applications in biomedicine, which can measure the full polarization state of the SH light. In this work, we describe the application of a Stokes-vector-based four-channel photon counting SHG microscope to determine the molecular interpretation of the SH light from collagen in normal, scar, and keloid tissue.
Low-level laser therapy in cases of burning mouth syndrome
Authors: Balcheva M , Balcheva G , Panov V , Madjova C
Published: April 2021

Burning mouth syndrome is an intraoral burning sensation which develops in the absence of mucosal changes. It is a chronic condition and, in most of the cases, it is idiopathic – no cause or mechanism can be identified and no effective treatment can be prescribed. A variety of therapeutic approaches have been applied – cognitive-behavioral therapy, different drugs and supplements, acupuncture, lasers – none of them has achieved a definitive solution of the problem. This leads to anxiety, altered pain perception, and, therefore, reduced quality of life of the affected patients. The aim of this study is to present low-level laser therapy as a pain control option in patients with burning mouth syndrome. We reveal the potential of a diode laser to reduce the unpleasant burning sensation. We also apply laser therapy on patients with primary burning mouth syndrome. The affected sites on the oral mucosa in the selected cases are various – tongue, lower lip, upper lip, palate, cheeks. They are irradiated 10 times (two or three times a week) by an infrared laser (λ = 904 nm) and a red laser (λ = 658 nm). The probe is kept in contact with the tissue and the mucosal surface is scanned during the irradiation. The burning intensity is evaluated through a visual analogue scale before and after the treatment. The low-level laser illumination decreases significantly and for a longer period the burning sensation. The low-level laser therapy is a valuable alternative for BMS treatment and can be combined with other treatment methods.
Theoretical study of laser-based phototherapies’ improvement via upconverting nanoparticles
Authors: Spyratou E , Kareliotis G , Makropoulou M , Efstathopoulos E , Serafetinides A A
Published: April 2021

The introduction of new upconverting nanoparticles (UPCNPs) in the tumor area is being investigated worldwide as a solution for deep tissue theranostics interventions. Moreover, as the development of biophotonics techniques permits bioimaging in nanoscale, both photodynamic and photothermal sensing should be achieved even at cellular level with minimum perturbation, i.e., in absence of any physical contact between cells and sensing units at a single-cell level via optical tweezers. In our work, we discuss the biophotonic upconversion mechanism of nanoparticles’ excitation/emission at cellular level, under laser trapping conditions, via considering laser radiation of NIR (specifically at λ = 808 nm) for optimal penetration in biological tissues. Moreover, a theoretical simulation model will be presented for evaluation of the electric field distribution in optically trapped particles. Water soluble UPCNPs with maximum absorbance wavelength at λ = 808 nm and emission at 545 nm and 660 nm will be studied. The photoluminescence of biocompatible UPCNPs could provide a promising powerful tool for PDT single-cell analysis and/or for photothermal enhancement and sensing in an optical tweezers’ platform.
Trapping, detection and manipulation of single Rb atoms in an optical dipole trap using a long-focus objective lens
Authors: Beterov I I , Yakshina E A , Tretyakov D B , Entin V M , Singh U , Kudlaev Ya V , Yu Mityanin K , Panov K A , Alyanova N V , Andreeva C , Ryabtsev I I
Published: April 2021

Single alkali-metal atoms in arrays of optical dipole traps represent a quantum register that can be used for quantum computation and simulation based on short-term Rydberg excitations, which switch the interactions between qubits. To load single atoms into optical dipole traps and then detect them by resonance fluorescence, lenses with a large numerical aperture (NA > 0.5) inside a vacuum chamber and expensive EMCCD cameras are commonly used. We present our recent experimental results on demonstrating the trapping of single 87Rb atoms using a long-focus objective lens with a low numerical aperture (NA = 0.172) placed outside the vacuum chamber, and detecting single atoms with a low-cost sCMOS camera. We also present our current results on implementing a single-qubit gate based on optical pumping and subsequent microwave transition between two hyperfine sublevels of a single 87Rb atom with fidelity near 95%.
Propagation of ultra-short dark soliton pulses in an isotropic medium under the influence of third-order linear dispersion and nonlinearity dispersion
Authors: Nenova B , Dakova D , Dakova A , Slavchev V , Kovachev L
Published: April 2021

The nonlinear Schrödinger equation (NSE) is well-known and is one of the most commonly used in the field of nonlinear optics. Pulses with picosecond and femtosecond duration are very well described by the NSE, but it does not work for attosecond and phase-modulated femtosecond laser pulses, where the spectral width of the pulse is of the order of the carrying frequency. In such cases, it is more convenient to use the general nonlinear amplitude equation (NAE). During the propagation of ultra-short pulses in optical fibers, the effects of the third-order linear dispersion and dispersion of nonlinearity become significant and have to be taken into account. We expanded the NAE by including these two effects. In this paper, we present an analytical study on the influence of third-order linear dispersion and dispersion of nonlinearity on the evolution of ultra-short optical pulses and on the possibility of dark soliton formation under such conditions in a medium with normal dispersion.
High-power high-beam-quality sealed-off master oscillator – power amplifier system oscillating in the middle infrared spectral range on strontium atomic transitions
Authors: Kostadinov I K , Yankov G P , Popova L T , Slaveeva S I , Fedchenko Yu I , Temelkov K A
Published: April 2021

High-beam-quality sealed-off master oscillator – power amplifier system is developed and studied based on an atomic strontium vapor laser and delivering high-power laser radiation in the middle infrared spectral range. A diffraction self-filtering of the laser radiation is used to reduce the laser beam divergence to the ultimate diffraction limit. A new optical design is utilized for the master oscillator to visualize the optical path through the entire optical scheme. A large-bore sealed-off laser tube is developed and studied with a stable cavity and is applied as a power amplifier as well. Precise microprocessing of optical grade fused quartz is also performed.
Antibacterial properties of Ta-based ceramic coatings deposited by magnetron sputtering
Authors: Donkov N , Zykova A , Safonov V , Yakovin S , Dudin S , Melnikova G , Petrovskaya A , Kuznetsova T , Chizhik S A
Published: April 2021

Combatting the bacterial infections is an important aspect of any postoperative therapy. Bacterial adhesion to the surface of a biomaterial depends on its properties, such as surface roughness, topography and wettability. The present study analyzes the composition and surface parameters of nanostructured Ta, Ta2O5, TaON coatings and the correlation with their antibacterial properties. The elemental distribution, phase and chemical composition of the coatings were explored by X-ray phase analysis and energy dispersive X-ray spectroscopy. The surface morphology and topography were observed by atomic force microscopy and electron scanning microscopy. The coated surfaces’ advancing contact angles were evaluated by tensiometric measurements. The results of the bacterial viability tests demonstrated the strong bactericidal activity of Ta-based coatings deposited by magnetron sputtering.
Accuracy evaluation of fixed prosthetic constructions made by milling and printing technologies and the influence of temperature changes
Authors: Galeva H , Uzunov T , Sofronov Y , Todorov G
Published: April 2021

The aim of this study is to evaluate the internal and external fit accuracy of fixed metal-ceramic prosthetic constructions made by milling and printing technologies and the influence of temperature changes on this accuracy. An acrylic resin tooth was prepared according to the standard guidelines for a metal-ceramic crown. A standard intraoral silicone impression was taken and a stone model was prepared. The stone model was scanned by an extraoral digital scanner and a digital copy of the prosthetic field was created. The digital copy was used to create a digital prototype of the future metal substructure for the metal-ceramic crown. Using the same data, the metal substructure was formed once by milling technology, and once by 3D-printing technology. The internal surface of both samples was measured. The stone model preparation surface was also measured. All data were compared to the digital prototype. According to the standard technology, a dental technician applied ceramic material, by hand as usual, in layers and the constructions were sintered. After the thermal procedure, once again the substructure’s internal surface was measured and compared with the previous data. The constructions were finished by glazing by the dental technician applying the last layer ceramic and sintering it. The construction’s internal surface was again measured and the data obtained were compared with the previous data. Conclusion about the influence of the temperature changes caused by the sintering process on the metal substructures was made using the data acquired by all the measurements made between the different stages. The difference in the internal fit of the constructions made by the milling and the 3D-printing technology will not affect to crown’s ergonomics. The quality of the internal fit for the construction made by milling technology is better than this made by 3D-printing technology. Unnoticeable changes in the internal surface were found after the temperature changes caused by the process of sintering for both types of constructions. Both types of technologies could be used to produce high quality accurate metal substructures for the needs of the fixed prosthetic dental medicine. The temperature changes caused by the sintering process during the standard metal-ceramic technology have a small influence to the construction’s internal fit.
Effect of Ni and Al substitution on the magnetic properties of Y-type hexaferrite Ba0.5Sr1.5Zn0.5Ni1.5Fe11.92Al0.08O22 powders
Authors: Georgieva B , Kolev S , Krezhov K , Ghelev Ch , Kovacheva D , Tran L-M , Babij M , Zaleski A , Vertruyen B , Closset R , Koutzarova T
Published: April 2021

The effect is reported of substituting the non-magnetic Zn2+ cations with magnetic Ni2+ cations, and of the magnetic Fe3+ cations with non-magnetic Al3+ cations in Ba0.5Sr1.5Zn0.5Ni1.5Fe11.92Al0.08O22 on the resulting magnetic properties. The Y-type hexaferrite powders were synthesized by citric acid sol-gel auto-combustion, followed by appropriate thermal annealing. The saturation magnetization values (Ms
) in a magnetic field of 50 kOe were 36 emu/g and 30 emu/g at 4.2 K and 300 K, respectively. The zero-field-cooled (ZFC) and field-cooled (FC) magnetization vs. temperature (4.2 – 300 K) were measured in dc magnetic fields of 50 Oe, 100 Oe and 500 Oe. The changes resulting from the dissimilar cationic substitutions were identified and discussed.
Research and Application of Intersection Clustering Algorithm Based on PCA Feature Extraction and K-Means
Authors: Lv Wei , Tang Weiyu , Huang Hongliang , Chen Tao
Published: April 2021

Traffic jam and traffic route design are important issues of people’s livelihood. In this paper, machine learning algorithm is used to cluster intersection features. Based on the collected traffic intersection data, PCA dimension reduction technology is used for feature extraction, and then K-Means clustering algorithm is used to sum up the number of entrances, and each intersection is clustered. Thus, a new intersection clustering algorithm is established, studied and applied. The algorithm can match similar intersections, which provides theoretical support for the transportation department and related technical personnel.
Target driven IP Geolocation Algorithm
Authors: Wang Zhanfeng , Niu Yan , Chen Hao , Cheng Guang , Cui Jiawei , Zhang Zhiyi
Published: April 2021

IP Golocation is an important technique to achieve network attack traceability, network security early warning, and improve the ability of cyberspace governance. Due to the limitation of collecting a large number of anchor nodes, it is impossible to accurately infer the IP location to block level or more in a large scale. Therefore, this paper proposes a target driven IP geolocation inference method. Firstly, the candidate anchor node is collected from the subnet or the adjacent subnet of the target IP, then the candidate anchor node is calibrated by their fingerprints, and finally the geolocation of target IP is comprehensively inference by its proximity to anchors. In order to verify the proposed method, 10,000 IPs in Beijing is selected randomly. The experimental results show that the method can effectively infer the geographical location of the target IP address.
Microservice Monitoring and Handoff Algorithm Based on Dual-node Hot Standby
Authors: Zheng Xiaojian , MA Chenzhi
Published: April 2021

The service provider nodes in distributed microservice architecture often exit, join the network or have faults, which will affect the availability of the system. One of the main causes of the problem is the “bump” of service nodes. In this paper, a monitoring and switching algorithm based on dual-node hot backup is adopted, which makes the probability of bumping lower than the traditional single machine and switching method. Moreover, with the gradual increase of system scale, the performance of dual-node hot backup algorithm is still stable. Experimental results show that this method can effectively reduce the occurrence of service consumption node access failure events and improve the availability of the system.