bluuebunny/crossref_metadata_2025_split huggingface dataset:
Riga Group’s recent results on laser applications for skin diagnostics
Authors: Spigulis J , Lukinsone V , Oshina I , Kviesis-Kipge E , Tamosiunas M , Lihachev A 
Published: April 2021

Abstract
The laser-related activities are reviewed of the Biophotonics Laboratory at UL Institute of Atomic Physics and Spectroscopy following the previous ICSQE-2018 conference. Four recent research projects are considered, including one EC Horizon-2020 project, two European Regional Development Fund (ERDF) projects and one project funded by the Latvian Council of Science (LCS). The projects are generally aimed at developing new optical methods and technologies for non-invasive in-vivo skin assessment to facilitate the early diagnostics of skin malformations (including cancers). Most of the projects explore novel approaches of camera-based biomedical imaging to the clinical diagnostics and recovery monitoring.
Low-level laser therapy in cases of dentin hypersensitivity
Authors: Balcheva G , Balcheva M , Panov V , Madjova C 
Published: April 2021

Abstract
Dentin hypersensitivity is characterized by short, sharp pain in response to a stimulus – thermal, drying, tactile, osmotic or chemical. These stimuli cause an unpleasant sensation lasting from seconds to minutes after provocation. Many alternative treatment methods have been introduced. One of the options is the use of low-level laser therapy, whose effect is based on the increase of the excitability threshold of the free nerve endings causing an analgesic effect, as well as on the stimulation of pulp mesenchymal cells to differentiate into odontoblasts and produce reparative dentin. To investigate the efficacy of low-level laser therapy in treating dentin hypersensitivity, we selected a group of patients complaining of sensitivity at the cervical area of teeth provoked by stimuli such as air, touch and cold spray. The patients were with good oral hygiene and with intact teeth or small non-carious cervical lesions. They confirmed the absence of serious systematic and psychological diseases; some of them smoked electronic cigarettes, which may aggravate the pain. The patients were submitted to six sessions of treatment of dentin hypersensitivity with intervals from 48 to 72 hours, as indicated by the manufacturer of the low-intensity laser device. The painful sensation was measured before each of the six sessions and immediately after the treatment. The results were evaluated by using a four-point scale. The answers assessment showed good results – there was a decrease of the pain sensation from 3-4 level to 1-2 level. Yet, we have to interpret this carefully, because pain evaluation is subjective and some of the smokers have quit smoking electronic cigarettes during the treatment. As a method of curing dentin hypersensitivity, the low-level laser therapy shows a good treatment efficacy, but needs further continuous follow-up.
Technological parameters optimization in picosecond laser texturing of titanium surfaces
Authors: Dikova T D , Kulinich S A , Iwamori S , Yamaguchi S 
Published: April 2021

Abstract
The present paper deals with studying the surface morphology of commercially pure (cp) Ti Gr-2 and Ti6Al4V treated by a picosecond laser and with determining the optimal technological parameters for fabricating cavities with a regular shape and a depth of about 10 μm. The surfaces of disk-shaped samples were treated by a commercial picosecond laser with a power of 0.2 W, 0.5 W and 1 W and a number of pulses between 1,000 and 20,000. The samples’ surface was investigated by SEM and a non-contact 3D surface profiler. The technological parameters were optimized by regression analysis using the QStatLab software. It was found that after laser treatment with the lowest values of the above parameters only the surface roughness changed in the case of cp-Ti, while its Ti6Al4V counterpart had a “melted zone” with a 5.5-μm depth. Raising the values of the regime parameters mainly led to an increased cavity depth on the cp-Ti surface, while those on Ti6Al4V increased in all dimensions. The surface roughness of both materials was higher after the laser treatment and grew bigger as the laser power and the number of pulses were increased. The optimal technological parameters for treatment of cp-Ti and Ti6Al4V were found. The results obtained can be used for picosecond laser texturing of titanium surfaces using linear or dimple types of patterns.
Endogenous and exogenous fluorescence diagnosis of tumors in the lower part of the gastrointestinal tract
Authors: Genova Ts. , Valkov H. , Vladimirov B. , Kolev B. , Angelov I. , Avramov L. , Borisova E. 
Published: April 2021

Abstract
Endogenous fluorescence measurements using UV-VIS excitation wavelengths revealed a variety of natural fluorophores, including the amino acids tyrosine and tryptophan, coenzymes – NADH and flavin, collagen and elastin. Deep minima in the tumor fluorescence signals were observed in the region 540 – 575 nm related to re-absorption of hemoglobin. Such high haemoglobin content was also found as an indication of the tumor’s vascularization and it was clearly pronounced in all dysplastic and tumor sites investigated ex vivo. A photosensitizer from the family of porphyrins was applied as an exogenous fluorescent marker, namely, delta-aminolevulinic acid/protoporphyrin IX (5-ALA/PpIX). The 5-ALA was administered per os six hours before endoscopic observation and spectral measurements at a dose of 20 mg/kg. A high-power light-emitting diode at 405 nm was used as an excitation source (LED-405, 25 mW, CW, Polironik Ltd., Russia). A fiber was introduced through an endoscopic instrumental channel in order to retrieve information about the fluorescence to a USB4000 micro-spectrometer (OceanOptics Inc., Dunedin, USA). The fluorescence detected from in vivo tumor sites has very complex spectral origins. It consists of autofluorescence, fluorescence from exogenous fluorophores and re-absorption from the chromophores accumulated in the investigated tissue. However, the fluorescence of 5-ALA/PpIX was clearly pronounced in the 630 – 710 nm region, having a significant contrast with the surrounding normal mucosa pale fluorescence in the blue-green spectral region. The precancerous mucosa also revealed a red light signal, but with lower intensity levels than the carcinoma lesions observed in situ. False-positive signals were recognized in case of inflammations in the colon and rectum areas, where 5-ALA/PpIX was accumulated as well.
Infrared thermography in the diagnostics of hidden infections – case reports
Authors: Grozdanova-Uzunova R 
Published: April 2021

AbstractTwo interesting case reports are presented that prove the many advantages of infrared thermography as a new diagnostic tool that can be successfully used in detecting hidden pathological processes. The first case report is about a 40-year-old female patient with alopecia areata – head lesion. The dermatological treatment gave no results, so the patient was sent for focal diagnostics. The infrared thermography showed two sites with hidden infection. The first one was of dental origin – periapical granuloma on the first mandibular left molar; the second site was in the genital area – endometriosis. A root canal retreatment of the molar and a gynecological operation were performed. After elimination of the focal infection, the hairless lesion recovered fully. The second case report is of a 34-year-old healthy male with alopecia areata of the beard and no other complaints. Infrared thermography detected active sinusitis of the ethmoidal left sinus. A microbiology test confirmed the presence of Staphylococcus Aureus and after an antibiotic course the beard recovered fully. These cases clearly illustrate the advantages of infrared thermography as a novel promising, non-invasive and objective diagnostic tool for clarification of difficult-to-diagnose cases.
Near-infrared autofluorescence spectroscopy and photobleaching detection of melanin-pigmented cutaneous neoplasia
Authors: Mircheva V , Zaharieva L , Ilyov S , Troyanova P , Lihacova I , Lihacovs A , Bratchenko I , Bratchenko L , Khristoforova Yu , Zakharov V , Avramov L , Borisova E 
Published: April 2021

Abstract
In the current study, an excitation laser source emitting at 785 nm (100 mW, CW) was used to obtain ex vivo fluorescence of endogenous melanin in pigmented skin with benign, dysplastic and malignant cutaneous lesions. The samples were obtained after surgical removal during standard excision procedure and split for spectral analysis and histological verification. The samples of benign (BN-5) and dysplastic (DN-3) nevi and of malignant melanoma (MM-7) were used as representative for harmless/harmful cutaneous neoplasia with a similar melanin pigmentation. Emission in the range 800 – 1100 nm was detected and compared using a USB4000 micro-spectrometer (Ocean Optics Inc., USA). The photobleaching dynamics was observed for the emission maxima at 825 nm for 10 minutes with a step of 20 s. These near-IR autofluorescence spectra may be assigned to a single fluorophore if appropriate excitation wavelength is applied, which simplifies the rapid analysis related to the appearance and concentration evaluation of a given type of endogenous fluorophore, as well as allows the evaluation of some parameters, such as photobleaching dynamics, as a diagnostic indicator assessing the tissue state. A diagnostic accuracy of 93.3% was achieved for MM lesions validation when the NIR fluorescence intensity and photobleaching rate values were used to discriminate between nevi and melanoma lesions.
Assessing temperature increase during photodynamic therapy: a simulation model
Authors: Kareliotis G , Kalkou M , Tsigaridas G , Makropoulou M , Serafetinides A A 
Published: April 2021

Abstract
Photodynamic therapy (PDT) is a non-invasive procedure mainly used for treatment of malignancies. It is based on cytotoxic products generation after the excitation of absorbed photosensitizing drugs by non-ionizing radiation. The wavelength chosen is usually in the 620 - 700 nm region, resulting in limited tissue penetration depth. The relatively low irradiance values and the treatment time that, in most cases, lasts for a few minutes result in limited photothermal effects, which are usually overlooked. Therefore, in this study we computationally assess the temperature distribution during PDT in a cancer bearing mouse model. A user-friendly application is created that could be used in the treatment planning step of PDT. It receives as input various parameters, such as laser power, beam radius, irradiation time, body temperature and returns the maximum tissue temperature and irradiance values. Furthermore, it offers visualization of the generated effects through the spatial distribution of temperature, irradiance, acute necrosis and damaged tissue percentage that are presented in the form of interactive 3D plots. The conducted simulations reveal that 43 °C, which are in the hyperthermia range, are difficult to be excessed in PDT clinical practice, although topical thermal effects are observed.
Minimization of spikes by pulse doubling pump in Q-CW operation of a Nd:YAG laser with flash lamp pumping
Authors: Bouadjemine R , Louhibi D 
Published: April 2021

Abstract
In this paper, we examine the factors minimizing the transient spikes in the evolution of a laser pulse. Our study is based on a mathematical model simulation of the laser implemented in Matlab Simulink. A model of the flash lamp excitation circuit is also included in the overall laser model. It allows us to show the correlation between the characteristics of the Q-CW laser pulse mode and the various physical parameters of the oscillator. The model proposed is applicable to the case of a single- or multiple-mesh pulse-forming network (PFN) of the flash lamp excitation current. The spikes in the laser pulse are substantially reduced by using the pulse doubling pump (PDP) technique. The simulations results give a clean laser pulse in a single mesh and in five meshes.
Numerical study of a ring-array-concentrator for Nd:YAG solar laser pumping
Authors: Boutaka R , Bouadjemine R , Liang D , Hendaoui N , Kellou A 
Published: April 2021

Abstract
In this paper, we report a numerical study of a Nd:YAG solar laser side-pumped by a ring-array concentrator (RAC) system. We used the ZEMAX© and LASCAD© software to optimize a 1.5-m diameter RAC system, a 3V-shaped pump cavity within which a Nd:YAG single-crystal laser rod (4-mm diameter, 30-mm length) is mounted, and the laser resonator parameters. The multimode solar laser output power was numerically calculated to be 34.8 W in a continuous-wave mode, corresponding to a solar laser collection efficiency of 19.69 W/m2, a slope efficiency of 3.07%, and 2.3% solar-to-laser conversion efficiency, indicating an improvement of 2.05, 1.31, and 1.5 times, respectively, relative to that of the previous results for a side-pumped Nd:YAG solar laser. Moreover, this study is the first numerical analysis of a Nd:YAG solar laser side-pumped by a RAC concentrator.
RF magnetron sputtering of Bi12TiO20 thin films on various substrates
Authors: Balchev I , Nurgaliev T , Kostadinov I. , Lakov L , Aleksandrova M , Avdeev G , Valcheva E , Russev S , Genkov K , Milenov T 
Published: April 2021

Abstract
Using RF magnetron sputtering, we deposited Bi12TiO20 (BTO) thin films on various substrates (glass, quartz, stainless steel (SS304), (001) and (111) Si and sital-ceramics, Al and Cu foils). The films had a constant thickness of 1.3 μm. The as-deposited films were studied by Raman spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX), as well as by grazing incidence X-ray diffractometry (GIXRD). The GIXRD results reveal that the films are amorphous, while the Bi/Ti ratio varies between 9.5/1 and 11.8/1, as shown by the energy dispersive X-ray analysis (EDX). Further, the films deposited on glass and SS304 substrates were modified by laser irradiation (CuBr laser with a wavelength λ = 511 nm) to obtain an ordered cubic phase. The films deposited on quartz and on (001) and (111) Si substrates were thermally annealed at about 510 oC for three hours in ambient atmosphere. The modified films were characterized by Raman spectroscopy, scanning electron microscopy (SEM), EDX and X-ray diffractometry.
Alternative technique for direct immobilization of biomolecules
Authors: Belina E , Karadjov J S , Shindarova K , Pavlova E , Dimitrowa T L , Kisov H , Dyankov G 
Published: April 2021

Abstract
The conventional approach to immobilization of biomolecules on the transducer of biosensors requires their embedding into the so-called embedding matrix. The procedure is complicated and laborious and performed by chemical means. As a results, not only biomolecules, but also other substances are deposited on the desired surface. This leads to reduced sensitivity and specificity due to the non-specific reactions with the molecules of the embedding matrix. Immobilization without embedding matrix (the so-called direct immobilization) guarantees the specificity of the biosensor and increases the sensitivity and accuracy. The main challenge in implementing this strategy is to preserve the bioactivity of the ligand. We have successfully solved the problem by using the matrix-assisted pulsed laser evaporation (MAPLE) technique. Here we report the properties of hemin directly immobilized on the transducer of a biosensor based on surface plasmon resonance (SPR).
Deep learning-based noise reduction for seismic data
Authors: Li Ying , Ma Zhonghua 
Published: April 2021

Abstract
An improved noise reduction algorithm based on feedforward denoising neural network (DnCNN) is proposed for the noise removal problem of noisy seismic data. The previous DnCNN originally used for noise reduction of seismic data had the problem of large network depth and thus reduced training efficiency. The improved DnCNN algorithm was first proposed for the noise reduction of natural data sets, and this paper applies the algorithm to the noise reduction of seismic data after adjusting the relevant parameters. The analysis and comparison of the experimental results show that the DUDnCNN algorithm can remove noise with high efficiency, and the algorithm has certain feasibility and significance for further research in seismic data noise reduction.
Study on Prediction of Course Failure Based on Improved Bagging-C4.5 Algorithm
Authors: Luo Jing 
Published: April 2021

Abstract
At present, the research of academic early warning system needs to know the situation of course failing. There are many research methods of course failing, but there are defects of low accuracy and long prediction time. In order to improve the accuracy and accuracy of course failing prediction, the improved Bagging-C4.5 algorithm is designed to predict the course failing. Firstly, the research progress of current social talent demand and course failure prediction is analyzed, then the test data set is determined, and the feature combination with the most influence is selected as the feature set of course failure prediction. Finally, the improved Bagging-C4.5 algorithm is used to realize the failure prediction, and the comparison test is conducted with other algorithms. The results show that the algorithm in this paper has high accuracy and accuracy in predicting course failure.
Prioritizing User Requirements based on Analytic Hierarchy Process
Authors: Tang Jiahui 
Published: April 2021

Abstract
As users have higher and higher requirements for products and competition in the product market becomes increasingly greater, how to use company resources more scientifically and quickly develop products that meet user needs becomes more and more important. Therefore, in this study, we apply the analytic hierarchy process for user requirement analysis, and clarify the advantages of the analytic hierarchy process compared with the existing commonly used models for prioritizing user needs and present the principles, methods, and results of the analytic hierarchy process in detail.
Application of SOM, BP Neural Network in Physical Health Assessment of Students
Authors: Ning Miao , Yong Lan , Ming Lu , Yun Liu 
Published: April 2021

Abstract
At present, the physical fitness measurement carried out by the school is an important way to detect the students’ physical health. How to use the students’ physical fitness scores to scientifically and reasonably evaluate the students’ physical fitness and health. This paper attempts to apply BP neural network to evaluate students’ physical health, use software to study and train the designed network, establish the corresponding neural network model, and use SOM neural network clustering to analyze the results of physical health. And realize the physical health evaluation of physical test results. Analysis of the results shows that the BP neural network can evaluate the physical health of the physical test results and show the quality of the students’ physical quality. By using BP neural network to evaluate physical health, the method is operable and has wide practicability, and provides the basis for the credibility of physical health.
Research on Portrait of Online Public Opinion Subject Based on Big Data of Public Opinion—A Case Study of Notre Dame
Authors: Jia Nan , Xia Yixue , Jia Ling 
Published: April 2021

Abstract
[Purpose/Significance] As online public opinion gradually becomes an important carrier of public opinion expression, multi-dimensional portrayal of each subject of public opinion based on public opinion big data helps to understand the characteristics of each dimension in an all-round way, thereby enhancing the pertinence of network social governance. This article aims to actively explore the subject of online public opinion subject based on public opinion big data and machine learning algorithms. [Method/Process]Use web crawler technology to crawl the microblog and comment data of the “Notre Dame” event, and describe it from the three dimensions of the basic attributes of microblog users, the microblog comment stand and the topic of microblog comments. In the basic attribute dimension, the reputation index of each user is calculated using information such as the number of fans and followers; in the Weibo comment stand dimension, machine learning algorithms are used to classify the comment stand, and the oversampling technique is used to oversample the data set Processing to improve the classification effect; in the microblog comment subject dimension, the LDA model is used to divide the subject of the review data; finally, a fusion portrait is developed based on the above portrait dimension.[Results/Conclusion]Through the integration of portraits, comprehensive use of image information such as microblog user influence, comment stances, comment topics, comment time, etc., to propose guidance strategies for different scenarios, helps to improve the targeted and effectiveness of network social governance.
Research on Feature Extraction Algorithm Commonly Used in Brain-computer Interface Technology
Authors: Zhang Yifan , Wang Yaojun 
Published: April 2021

Abstract
Brain-computer interface (BCI) is an effective and direct channel of information exchange between human brain and external devices such as computer, which can provide auxiliary information acquisition and treatment means for the medical and other fields in the future. This paper focuses on four kinds of feature extraction algorithms such as power spectral density (PSD), wavelet transform, Hilbert-Huang transform (HHT) and common space pattern (CSP), which are commonly used to process abnormal electroencephalogram (EEG) signals in brain-computer interface technology. This paper also introduces their respective principles, characteristics and application fields, analyzes and compares the advantages and disadvantages of these algorithms, and obtains the development direction of feature extraction algorithms in the future. Finally, it also briefly discusses the ethical issues brought about by brain-computer interface technology.
Big Data Infrastructure for Marine Environment in the Arctic and Ice Silk Road
Authors: Lin Bo 
Published: April 2021

Abstract
In this paper, the big data infrastructure for the marine environment in the Arctic and Ice Silk Road from National Marine Environmental Forecasting Center is taken as the main line, the construction of the Arctic observation system, the basic data construction of the Ice Silk Road and the construction of the high-performance computer system are described in detail, which clearly outlines the technical framework and construction progress of the Marine environmental data sources, data acquisition and transmission, data warehouse of the Arctic and Ice Silk Road. And from the perspective of climate change, the future of the Arctic and Ice Silk Road and the trend of corresponding marine environmental monitoring, warning (alarm), security assurance services and their big data infrastructure construction are prospected roughly.
Difference Analysis and Multiple Regression of College Students’ Network Behavior from the Perspective of Big Data
Authors: Jianjian Wang , Wenqiang Miao , Guofang Sheng , Zeyu Wang 
Published: April 2021

Abstract
With the rapid development of information technology, the Internet has become the main media and important way for college students to obtain information, learn and communicate. The advent of the era of new media has greatly enriched the means and approaches of ideological work in colleges and universities. Therefore, the research on college students’ Internet behavior is particularly important. Through questionnaire survey and using SPSS data processing software, this paper conducts a difference analysis on the network behavior of different groups of college students, carries out multiple regression on the influencing factors of college students’ network behavior, summarizes the existing problems and puts forward reasonable suggestions, so as to explore the leading path of ideological and political education on college students’ network behavior.