Study on the calibration for the outputs of photon and electron beams of dual-mode of linear accelerator based on IAEA 277 and 381 reports / 中国医学装备

Objective:To calibrate the absorbed doses of the configured ray water with different gears of energies in accelerator based on<The use of plane-parallel ionization chambers in high-energy electron and photon beams>of International Atomic Energy Agency(IAEA)277 and 381 reports,so as to ensure the accuracy of the output dose of the linear accelerator during clinical radiotherapy.Methods:Elekta Infinity linear accelerator was used in this study,and the photon beam energies were respectively 6MV flattening filter(FF)mode and 6MV flattening filter free(FFF)mode.The electron beam energies were respectively 4,6,8,10,12 and 15MeV.According to the IAEA TRS277 and TRS381 reports,the calibrations of output doses in photon and electron beam waters were performed respectively by using the PTW dosimeter,PTW30013 finger type of ionization chamber and PTW34001 parallel plate ionization chamber.The error of each step was analyzed,and the accuracies of the calibrations of using different standards for the output waters of linear accelerator were compared.Results:The output amounts of photon beams of FF mode and FFF mode of 6MV at the maximum dose point in water were respectively 1.003 and 1.008cGy/MU.The output amounts of the energy of each gear of electron beams of 4,6,8,10,12 and 15MeV at the maximum dose point in water were respectively 1.003,1.002,0.998,0.999,1.000 and 1.003 cGy/MU.The calibration of the output of each gear of energy rays at the maximum dose point in water was 1cCy corresponded to 1MU,which error was less than 1%.Conclusion:The calibration for the output dose amount of accelerator in water on the basis of IAEA TRS277 and trs381 can ensure the accuracy of the output dose of the accelerator.

Study on the value of dual energy index and atomic number combined with slope of energy spectrum curve in identifying components of urinary tract stones based on dual energy CT / 中国医学装备

Objective:To assess a value of dual energy index(DEI)and effective atomic number(Zeff)of dual-energy computed tomography(DECT)combined with slope of energy spectrum curve in identifying the component of urinary tract stones.Methods:The clinical and DECT imaging data of 111 patients with urinary tract stones who admitted to Nantong Haimen People's Hospital from October 2019 to October 2022 were selected,and the diameters of the urinary tract stones of all patients were<5 mm.The components of outside body stones of all patients were analyzed by infrared spectrum.The accuracy,sensitivity and specificity of the DEI,Zeff,slope of energy spectrum curve and the combination of the them were respectively calculated in identifying the components of urinary tract stones.Results:In 111 patients,the patients with calcium oxalate stones were 75(67.57%),and ones with hydroxyapatite were 15 cases(13.51%),and ones with uric acid stones were 21 cases(18.92%),and there were no other type of stone included cysteine.The differences of CT values(F=487.691,P<0.001),DEI values(F=395.553,P<0.001),Zeff values(F=818.689,P<0.001)and the slopes of energy spectrum curves(H=19.615,P<0.001)were statistically significant among the three types of stones.The overall accuracies of DEI,Zeff and slope of energy spectrum curve were 87.39%(97/111),84.68%%(94/111)and 81.98%(91/111)in identifying the components of urinary tract stone.The range of diagnostic accuracies of DEI,Zeff and the slope of energy spectrum curve was between 80%and 100%for calcium oxalate stones,hydroxyapatite and uric acid stones.The overall accuracy of DEI,Zeff combined with slope of energy spectrum curve was 94.59%(105/111)in identifying the components of urinary tract stones.The diagnostic accuracies of DEI,Zeff combined with slope of energy spectrum curve were respectively 94.59%,94.59 and 100%for calcium oxalate stones,hydroxyapatite and uric acid stones.Conclusion:Compared with the single indicator of DECT,the DEI and Zeff combined with the slope of the energy spectrum curve showed better diagnostic accuracy in identifying the components urinary track stones.

Deep Learning Image Recognition-assisted Atomic Force Microscopy for Precise and Efficient Detection of Single-cell Mechanical Properties / 生物化学与生物物理进展

ObjectiveThe advent of atomic force microscope (AFM) provides a powerful tool for the studies of life sciences. Particularly, AFM-based indentation assay has become an important method for the detection of cellular mechanics, yielding numerous novel insights into the physiological and pathological activities from the single-cell level and considerably complementing traditional biochemical ensemble-averaged assays. However, current AFM indentation technology is mainly dependent on manual operation with low efficiency, seriously restricting its practical applications in the field of life sciences. Here, a method based on the combination of deep learning image recognition and AFM is developed for precisely and efficiently detecting the mechanical properties of single isolated cells and clustered cells. MethodsThe YOLO deep learning algorithm was used to recognize the central region of the cell in the optical image, the dual UNet neural network with an embedded vision transformer (ViT) module was used to recognize the peripheral regions of cell, and the template matching algorithm was used to recognize the tip of spherical probe. Based on the automatic determination of the positional relationships between the microsphere tip and the different parts of cell, the AFM tip was accurately moved to the central and peripheral regions of the target cell for rapid measurements of cell mechanical properties. Two types of cells, including HEK 293 cell (human embryonic kidney cell) and HGC-27 cell (human undifferentiated gastric cancer cell), were used for the experiments. The Hertz model was applied to analyze the force curves obtained on cells to obtain cellular Young’s modulus. ResultsAFM probe can be precisely moved to the different parts (central areas and peripheral areas) of cells to perform mechanical measurements under the guidance of deep learning-based optical image automatic recognition. The experimental results show that the proposed method is not only suitable for single isolated cells, but also suitable for clustered cells. ConclusionThe research demonstrates the great potential of deep learning image recognition to aid AFM in the precise and efficient detection of cellular mechanical properties mechanics, and combining deep learning-based image recognition with AFM will benefit the development of high-throughput AFM-based methodology to measure the mechanical properties of cells.

Antimicrobial activity of Er, Cr: YSGG and Ultrasonic on E. faecalisbiofilm in the mesial root canal systems of lower molars / Atividade antimicrobiana de Er, Cr: YSGG e Ultrassônico no biofilme de E. faecalis nos sistemas de canais radiculares mesiais de molares inferiores

The internal topography of the root canal is complex, especially for the permanent molar's mesial root. In response to such issues, improved irrigation techniques have been created, which use laser pulses to agitate fluids and improve microbial deposit removal. Objective: To assess the effectiveness of the Er,Cr:YSGG laser with a wavelength of 2,780 nm via photon-induced photoacoustic streaming (PIPS) protocol which agitated of 2% chlorohexidine (CHX) in removing mature Enterococcus faecalis (E. faecalis) biofilm in root canal systems of lower molars. Material and Methods: The mesial roots of lower first and second molars were separated and inoculated with E. faecalis bacterial suspension for 30 days. The roots were irrigated with CHX, some of them were agitated with a passive ultrasonic device (PUI), while the other roots were agitated by an Er,Cr:YSGG laser in PIPS at 60 µs/pulse, 5 Hz, (0.25, 0.5, 0.75, and 1) W. An atomic force microscope (AFM) was used as a new method to get the results in the isthmus area; the obtained results from each group were compared with each other. Results: Based on the AFM and SEM analyses, laser and ultrasonic activation groups showed higher antimicrobial efficacy than the conventional syringe irrigation group (P<0.05). Conclusion: Based on the investigation's findings, the activation of 2% CHX solution by Er,Cr:YSGG laser in PIPS and PUI offers better mature bacterial biofilm removal in the mesial root of lower human molars than the same irrigant with the SI technique (AU)

A topografia interna do canal radicular é complexa, especialmente para a raiz mesial do molar permanente. Em resposta a esses problemas, foram criadas técnicas aprimoradas de irrigação, que utilizam pulsos de laser para agitar fluidos e melhorar a remoção de depósitos microbianos. Objetivo: Avaliar a eficácia do laser Er,Cr:YSGG com comprimento de onda de 2.780 nm via protocolo de streaming fotoacústico induzido por fótons (PIPS) que agitou clorohexidina a 2% (CHX) na remoção de Enterococcus faecalis maduro (E. faecalis) biofilme em sistemas de canais radiculares de molares inferiores. Material e Métodos: As raízes mesiais de 28 primeiros e segundos molares inferiores foram separadas e inoculadas com suspensão bacteriana de E. faecalis por 30 dias. As raízes foram irrigadas com CHX, sendo algumas delas agitadas com aparelho ultrassônico passivo (PUI), enquanto as demais raízes foram agitadas com laser Er,Cr:YSGG em PIPS a 60 µs/pulso, 5 Hz (0,25, 0,5, 0,75 e 1) W. Um microscópio de força atômica (AFM) foi utilizado como um novo método para obter os resultados na área do istmo; os resultados obtidos de cada grupo foram comparados entre si. Resultados: Com base nas análises de AFM e SEM, os grupos de ativação por laser e ultrassom apresentaram maior eficácia antimicrobiana do que o grupo de irrigação com seringa convencional (P<0.05). Conclusão: Com base nos achados da investigação, a ativação da solução de CHX a 2% pelo laser Er,Cr:YSGG em PIPS a (60 µs/pulso, 5 Hz, 0,75 W) oferece melhor remoção de biofilme (AU)

Quantitative determination of selected heavy metals and micronutrients in branded dairy products sold in Nigeria using atomic absorption spectroscopy (AAS)

Quantitative analysis of heavy metals and nutrients in food helps indicate the safety and quality of food for final consumers. The present study was conducted to assess the presence of heavy metals (arsenic, copper, mercury, chromium, and lead) and the nutritional value of calcium in branded milk and yogurt to evaluate health risks for consumers. Ten (10) samples of branded milk and dairy products manufactured in Nigeria were purchased. The metal contents of the samples were determined using atomic absorption spectroscopy. The concentrations of calcium in the milk samples were between 9.33 ± 0.0023 and 18 ± 0.0071 ppm and were detected in all samples. Arsenic concentrations ranged from 0.45 ± 0.00042 to 2.48 ± 0.00064 ppm in eight branded samples but were undetected in two samples. Chromium levels were undetected in most samples, except for two with concentrations of 0.12±0.00049 ppm and 0.23±0.00021 ppm, respectively. Copper ranged from 0.032±0.00021 ppm to 0.129±0.00021 ppm in six samples. Mercury levels were detected in six samples at a concentration of 1.0±1.0 ppm. Lead concentrations ranged from 0.15±0.00064 to 0.29±0.00028 ppm in three samples. The study found heavy metals above the ideal concentration in branded milk and dairy products in Nigeria, highlighting the need for quality control measures during production to prevent contamination.

The properties of ZnO nanofilms on titanium surface by atomic layer deposition / 口腔医学

Objective@#To compare and investigate the physicochemical characteristics and antibacterial effect of ZnO nanofilms prepared by atomic layer deposition(ALD) at different deposition cycles.@*Methods@#According to different ALD cycles, four groups were set up (control group, 300, 600 and 1 200 cycles group). Using DEZn and water as precursors, ZnO nanofilms were prepared by ALD on the surface of pure titanium specimens. Surface morphology of the films was observed by scanning electron microscope (SEM); the element composition and crystal type of the films were observed by energy dispersive spectrometer (EDS) and X-Ray Diffraction (XRD); the hydrophilicity and thickness of the films were detected by water contact angle detector and ellipsometer. The cytotoxicity of the films was evaluated by CCK-8 assay. The antibacterial effect against S. aureus in vitro of the films was evaluated by optical density method.@*Results@#The surface morphology of the films was uniform and compact as shown through SEM. The grain size increased with the increase of the number of ALD cycles. EDS results showed that the films were mainly composed of Zn and O elements. XRD results confirmed that the composition of the films was ZnO. Results of water contact angle showed that the films were hydrophobic. The thickness of the films was nanoscale and there was a linear relationship between the thickness and ALD cycles. All experimental groups showed no cytotoxicity. The 1 200 cycles group showed the highest antibacterial rate of 65.9% and 52.3% at 24 and 48 hours respectively, which was the best among all experimental groups. @*Conclusion@#The ZnO nanofilms prepared by ALD at different cycles on pure titanium surface are uniform and compact. Thickness of the films increases with the increase of ALD cycles. The films have good biocompatibility and anti-S. aureus effect in vitro. The 1 200 cycles group has the best antibacterial effect.

Effects of fiber surface deposited with silicon dioxide films on properties of fiber-reinforced composites / 口腔医学

Objective@#To investigate the effects of fiber surface deposited with silicon dioxide films by atomic layer deposition on properties of dental fiber-reinforced composites.@*Methods @#SiO2 films were deposited on the surface of quartz fiber by atomic layer deposition(ALD). Then the quartz fiber was used to manufacture fiber resin composites, which were divided into four groups: A(no soaking agent removal), B(soaking agent removed), C(soaking agent removed and silanization), and D(soaking agent removed, 600 ALD cycles performed and then silanization). Scanning electron microscopy, water contact angle test, hygroscopicity test, CCK8 test and three-point bending test were used to investigate the properties of fiber resin composites.@*Results@#The surface morphology of the quartz fiber treated by ALD was smooth and had no obvious change compared with that before treatment. Moreover, the quartz fiber showed hydrophobicity after silanization. The results of three-point bending test revealed that the mechanical properties of fiber-resin composites modified by ALD were significantly improved(P<0.05). When viewed by scanning electron microscopy, a good interfacial bonding could be seen between quartz fibers and the resin matrix in Group D. In addition, it was found that Group D had low absorbability, low solubility and good biocompatibility. @*Conclusion@#It is shown that deposition of SiO2 films on the quartz fiber by ALD can significantly enhance the mechanical properties of fiber-reinforced composites.

Correlation between in-vivo mercury exposure from Cinnabaris and memory disorders in juvenile rat / 中国药科大学学报

@#Cinnabaris(α-HgS) is a mineral traditional Chinese material medica, as a tranquilizer and sedative, which is widely used in combination with herbs for the treatment of children high fever and convulsion.However, a large amount of mercury in Cinnabaris poses a potential risk to the immature central nervous system of children and probably causes severe memory disorders.Inthisstudy,three groups of juvenile rats were given low, medium, and high doses of Cinnabaris by oral gavage once a day for 14 continuous weeks, respectively.The blood mercury concentrations of the rats at different growth phases were monitored by atomic fluorescence spectrometry.The brain structural and functional changes related to the memory functions were investigated through HE staining and Morris water-maze test. Correlation analysis was conducted to clarify the dose- mercury exposure-toxic effect relationship of Cinnabaris and memory disorders.It was found thatthe blood mercury levels increased in both time- and dose-dependent manner.After the 14-week continuous administration of Cinnabaris, the pathological lesions in hippocampal neurons of rats in the high dose group were observed including pyknosis and disordered cell arrangement.In the Morris water-maze test, compared with the control group, rats in the high dose group exhibited the significantly prolonged latency to find the platform and the target quadrant, and the time spent in the target quadrant was obviously shortened. Thus, the significant correlations were established between Cinnabaris dose and mercury exposure,mercury exposure and memory disorders, respectively. In conclusion, the long-term and overdose administration of Cinnabaris in juvenile rats can increase the in-vivo mercury level, destroy the normal hippocampal morphological structure, and lead to memory disorders. This study provided scientific references for the potential mercury poisoning risks pharmacovigilance of Cinnabaris-containing paediatric formulations.

Evaluation of the heavy metals tolerant UV rays treated bacteria isolated from anthropogenic sites of Chambal region, India

Industrial waste is released into the environment and leads to various types of heavy metal, which are toxic, mutagenic and carcinogenic in nature. Heavy metals are not biodegradable but accumulated by living organisms and cause diseases at even low concentrations. In this study, we selected four anthropogenic sites from Chambal region, isolated bacteria and investigated its heavy metal removal capability. The bacteria was isolated and identified as Escherichia coli (Ag-5), on the basis of biochemical and 16S rRNA gene sequence. Among the five (cadmium, cobalt, lead, nickel and zinc) heavy metals studied, Ni2+ has been observed to be highly toxic with minimum inhibitory concentration score of 200 ppm. E. coli could tolerate Zn2+ (300 ppm), Cd2+ (400 ppm), Co2+ (400 ppm) and Pb+2 (500 ppm). Heavy metal tolerance capability was also evaluated by UV rays treated E. coli (Ag-5) isolate and compared with wild strain Ag-5. The result indicated that the tolerance capability was enhanced by UV rays treated bacterial isolate as compared to wild strain with respect to all tested heavy metals. Atomic absorption spectroscopy results revealed that wild strain removed 78.2% cadmium nitrate, while UV rays 30 and 60 s. exposed strain removed 85.9 and 83% cadmium nitrate. Wild strain removed 64.4% nickel chloride, while UV rays 30 and 60 s exposed strain removed 66.9 and 74.5% nickel chloride. The results indicate that indigenous E. coli treated with UV rays could serve as heavy metal tolerant bacteria and utilized in bioremediation processes.

Assessment of Arsenic (As), Lead (Pb) and Chromium (Cr) Accumulation in Different Organs of Commercially Important Fish Species Collected from Chattogram Coastal Region of Bangladesh.

Aims: The purpose of this study was to evaluate whether there are any significant toxic effects of the widely exposed metals on different organs (gill, liver, kidney, and muscle) of some commercially important marine fish species (Herpodon nehereus, Pampus chinensis and Hilsa ilisha). Study Design: The collection of the samples was done from January to March 2018 from Bay of Bengal near Chattogram city of Bangladesh. The study is based on randomly collected samples from the intended sampling sites (Randomized Block Design) to ensure the evenness and unbiases of the collected samples. Methodology: Analyses were performed for metals such as arsenic (As), lead (Pb) and chromium (Cr) using Atomic Absorption Spectrophotometer (AAS). During each month, five individuals each with three replications from the three targeted species were collected, with a total of 135 (45*3) fishes in the study period. Results: The concentrations of the metals found in the fishes varied in the following ranges: As: 0.029-0.071 ppm, Pb: 0.008-0.083 ppm and Cr: 0.0001-0.03 ppm. The obtained result revealed the highest concentrations of all three metals were recorded in H.nehereus fish. The organ wise lead concentration was recorded highest in kidneys and gills of examined fishes with significant variation in muscles and liver. The scenario depicted quite differently in case of chromium where concentration in gills was found to be the highest with insignificant variation in accumulation in other three organs. In case of Arsenic, kidneys and livers were the most exposed two organs in comparison to significant exposure to muscles and gills. The obtained values of arsenic accumulation were considered critical for human consumption as it was higher than the recommended values stated by WHO and FAO; but the concentration of lead and chromium were found to be safe for human consumption. The values recorded for lead were increasingly approached to the safety values. Conclusion: So, crucial steps should be taken regarding safety and environmentally friendly discharge of arsenic and lead; high levels of pollution will not only affect aquatic life but will also invite socio-economic disasters.

Application of atomic force microscope in the study of enamel with dental fluorosis / 中华地方病学杂志

At present, the exact pathogenesis of dental fluorosis is not clear, and there is no exact standard of enamel acid etching in the adhesive restoration of dental fluorosis. Atomic force microscope represents a great progress in high-resolution imaging of biomaterials, and its advantage is that it can provide three-dimensional images and quantitative data of observed samples at the nanometer level. In recent years, the application of atomic force microscope in enamel study has made some progress. Whether the quantitative analysis of enamel ultrastructure can become a new way to study the pathogenesis of dental fluorosis and find the best repair method is worthy of further exploration. This paper reviews the application of atomic force microscope in the study of enamel with dental fluorosis.

Determination of arsenic in urine by hydride generation atomic fluorescence spectrometry with ammonium persulfate digestion / 中华地方病学杂志

Objective:To establish a hydride generation atomic fluorescence method using ammonium persulfate as the digestion reagent for determination of arsenic in urine (hereinafter referred to as this method).Methods:The collected urine samples with ammonium persulfate were heated and digested on the tubular electric heating automatic control constant temperature digester (60 holes), with 5% hydrochloric acid solution as reaction medium and current carrier and 1.5% potassium borohydride solution as reducing agent. Arsenic content was determined with a four-channel atomic fluorescence spectrometer. The arsenic standard solution of 0 - 10 μg/L was prepared to determine the standard curve of this method, and the method was evaluated from the detection limit, linear range, correlation coefficient, precision, standard addition recovery experiment, and urine arsenic quality control sample detection. The standard method "Determination of Arsenic in Urine by Hydride Generation Atomic Fluorescence Spectrometry" (WS/T 474-2015, referred to as the standard method) was used for comparison experiments.Results:When the sampling volume was 1 ml, the detection limit of this method (digest with 1 ml 1.5 mol/L ammonium persulfate) was 0.03 μg/L. In the range of arsenic content from 0 - 10 μg/L, the linear relationship between arsenic content and fluorescence intensity was good, and the correlation coefficients ( r) were all 0.999 9. The relative standard deviations( RSD) of the three replicates of urine samples with different concentrations were 1.00%, 0.89% and 0.49%, respectively. Urine arsenic quality control samples were tested, and the test results were all within the range of public values; the overall average recovery was 102.29%, and the recovery range was 92.10% - 108.15%. Compared with the standard method in the determination results of 20 urine samples, the difference was not statistically significant ( t = - 0.40, P > 0.05). Conclusions:The hydride generation atomic fluorescence spectrometry using ammonium persulfate as digestion reagent for the determination of arsenic in urine has the advantages of low detection limit, good precision, high accuracy, small amount of sampling and digestion reagent, simple operation, and less harmful gas generation in sample pretreatment. It is suitable for rapid determination of arsenic in urine in large quantities.

Identification of Growth Years of Scutellariae Radix By Characteristic Spectrum of Inorganic Elements Combined with Chemometrics / 中国实验方剂学杂志

ObjectiveTo obtain content characteristics of inorganic elements in Scutellariae Radix （aged 1-4 years）， and to explore the feasibility of identifying the growth years of Scutellariae Radix based on characteristic spectrum of inorganic elements combined with chemometric models. MethodAfter microwave digestion， the contents of Mn， Zn， Ca， Fe， Mg， Na， K， Cr， Cu， Se， As， Cd， Hg， Pb and Ni in 21 batches of Scutellariae Radix were determined by inductively coupled plasma atomic emission spectrometry （ICP-OES） and inductively coupled plasma mass spectrometry （ICP-MS）. Meanwhile， characteristic spectrum of inorganic elements in samples was drawn. The identification model was constructed to discriminate the growth years of Scutellariae Radix based on the combination of principal component analysis （PCA）， Fisher discriminant function and support vector machine （SVM）. ResultThe contents of Mn （7.79-36.48 μg·g-1）， Zn （10.12-31.43 μg·g-1）， Cu （6.38-17.20 μg·g-1）， K （2.98-13.89 μg·g-1）， Mg （3.45-7.78 μg·g-1） and Ca （2.32-7.09 μg·g-1） in Scutellariae Radix were detected by ICP-OES and ICP-MS， and their contents increased with the prolongation of growth years. PCA results showed that Cu， Ni， Cd， Na， Mg， Fe， Ca， Zn， Mn and Hg were characteristic elements of Scutellariae Radix. Samples with different years could be divided into four categories in the spatial characteristic diagram of Fisher discriminant analysis. The correct rate of SVM model for identifying the growth years of samples was 95.2%. ConclusionThis established method is accurate and rapid for discriminating the growth years of Scutellariae Radix， which can provide reference for the identification of other Chinese medicinal materials. It is suggested that some elements should be considered as indexes in subsequent construction of the quality evaluation system of Scutellariae Radix.

Different Head Group Dependence on the Lipid ThermodynamicProperty of the Myelin Basic Protein in the Lipid Monolayer / 中国生物化学与分子生物学报

The 18. 5 kD myelin basic protein (MBP) isoform interacts with phospholipids and its role has been thought to maintain the stability and compactness of the myelin sheath structure. In this study, we describe the statistical thermodynamic theory of certain concentration effects on MBP in the majormyelin lipid (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethano-lamine (POPE), and 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine(POPS)) monolayers at the air/ subphase interface via the Langmuir-Blodgett (LB) technique. A simple statistical mechanical theory is established that predicts the interaction between proteins and phosphatehead groups at low surface pressures and the second virial coefficient dependences for the PC, PE, and PS head groups are illustrated. Two-dimensional virial equation of state (2D-VES) suggested that the interaction in the monolayer structure at the MBP-myelin interface is a repulsive force, and it induces a phase change in the monolayer. This is consistent with atomic force microscope (AFM) observations of domain and aggregate structures as well as with changes in the surface morphology induced by MBP. These analyses pertaining to membrane structures will provide a theoretical and experimental basis for the establishment of the myelin membrane modeling system.

Determination of tin and its compounds in ambient PM2.5 by atomic fluorescence spectrometry after ultrasonic extraction with concentrated hydrochloric acid / 环境与职业医学

Background Tin and its compounds can cause serious harm to human respiratory system and nervous system, but there is no corresponding national standard method for the determination of tin in PM2.5. Objective To establish a method for the determination of tin and its compounds in PM2.5 by atomic fluorescence spectrometry (AFS) after ultrasonic extraction with concentrated hydrochloric acid. Methods We extracted a fixed volume of air at a constant speed through a sampler with preset cutting characteristics to trap PM2.5 in the ambient air on quartz filter membranes. By selecting extraction solvent, comparing extraction temperature and time, and adjusting the acidity of solution to be measured, the sample pretreatment process was optimized, and a method for the determination of tin and its compounds in PM2.5 by AFS was proposed, and its performance indexes such as linearity, detection limit, and lower limit of quantification were obtained. The accuracy and precision of the method were evaluated by the standard addition recovery test with blank quartz filter membranes, and the interference test was carried out by adding standard urban particulate samples. The proposed method and the method recommended by the “Handbook on Monitoring and Protection of Air Pollution (Haze) Effects on Population Health (2020)” (the Handbook) were applied to actual samples, and the results were compared. Results This experiment used concentrated hydrochloric acid as the extraction solvent. The higher the reaction temperature and the longer the reaction time, the higher the recovery rate. Therefore, 70 ℃ water bath ultrasonic extraction for 3 h was selected. In terms of the proposed method, the linear range of detection was from 5.00 μg·L−1 to 50.00 μg·L−1, with a correlation coefficient ≥0.999 and a detection limit of 0.27 μg·L−1. When the quantitative detection of the lower limit was 0.90 μg·L−1，and the sampling volume was 144 m3, the limit of quantification was 1.25 ng·m−3. The recovery rate of standard addition of blank quartz filter membranes was 94.1%-97.5%, with a relative standard deviation ≤3.2%; the recovery rate of standard addition of standard urban particulate matter samples was 93.5%-103.0%, and the relative standard deviation was ≤2.1%, indicating that coexisting components in PM2.5 samples would not affect the determination of tin. For the 10 quartz filter membrane samples of PM2.5 monitoring, the results of tin by the established method (extraction with concentrated hydrochloric acid) were higher than those of the Handbook recommended method (extraction with nitric acid), and the difference is (3.61±0.54) ng·m−3(t=21.303, P<0.05). Conclusion The established method for the determination of tin and its compounds in PM2.5 by AFS after ultrasonic extraction with concentrated hydrochloric acid is simple, accurate, and suitable for laboratory determination of tin and its compounds in large quantities of PM2.5 samples.

Analyzing the difference between atomic fluorescence spectrometry and ICP-MS in the determination of arsenic in urine / 中国职业医学

@#Abstract: Objective （ ） To compare the measured results of arsenic in urine by atomic fluorescence spectrometry AFS and - （ - ）， Methods inductively coupled plasma mass spectroscopy ICP MS and analyze the reasons of the difference. The samples WS/T 474-2015 Determination of Arsenic in Urine by Hydride Generation Atomic Fluorescence were pretreated according to Spectrometry， （ ∶ ∶ ∶∶ ，V/V/V） and digested with mixed acid nitric acid sulfuric acid perchloric acid=3 1 1 and then determined by - - AFS and ICP MS. The samples were diluted with 0.50% nitric acid and determined by ICP MS. The samples included urine ， ， （ arsenic quality control samples inorganic arsenic supplemented samples and organic arsenic arsenic choline and arsenic ） - betaine supplemented samples. Standard curve method was used to compare the results of AFS method and ICP MS method. Results （ ） （ ） The results of quality control samples by AFS method digestion and ICP-MS method without digestion were ， - within the range of reference values but the values obtained by AFS method were lower than those obtained by ICP MS method. - - - ， The recovery of AFS and ICP MS was 97.79% 100.82% and 99.55% 99.98% respectively. In the middle and high ， - （ P ） concentration groups the measured values of inorganic arsenic by AFS were lower than that by ICP MS all <0.01 . The （ ） - recovery of arsenic betaine and arsenic choline by AFS method digestion was only 2.17% 2.63%. The values of arsenic betaine （ ） - （ and arsenic choline measured by AFS method digestion were lower than those measured by ICP MS method without ） - （ ）（ P ）Conclusion digestion and ICP MS method digestion all <0.01 . The result of urine arsenic measured by AFS method - ， was lower than that measured by ICP MS method which may be related to the mixed acid digestion of AFS method. Keywords: ； - ； ； ； ； ；

Research progress of radiation carcinogenic effect and its interference factors for survivors of the atomic bomb disaster in Japan / 中国辐射卫生

Based on the study of solid cancer incidence in survivors of the atomic bomb disaster (atomic bomb survivors) from 1958 to 1998, the Radiation Effects Research Foundation (RERF) performed an additional 11-year follow-up (1999—2009) to further investigate the 50-year solid cancer incidence of atomic bomb survivors from 1958 to 2009. Considering influencing factors such as gender, smoking, drinking, body mass index, and medical exposure, we updated the radiation risk estimate for solid cancer and found a new problem of the relationship between gender-specific dose response, exposure age and cancer incidence during the study, which provides guidance for future research.

Cyclic Fatigue Resistance and Surface Roughness of Rotary NiTi Instruments after Simulated Clinical Use in Curved Root Canals - An Atomic Force Microscopy Study

Abstract Objective: To examine the cyclic fatigue resistance and surface topography of TruNatomy and ProTaper Gold nickel-titanium rotary files and evaluate the presence of alterations to surface topography following instrumentation in simulated curved canals. Material and Methods: Twenty-four nickel-titanium instruments, twelve each of TN and PTG file systems, were evaluated for cyclic fatigue resistance. The rotary files were rotated in a simulated root canal with standardized diameter, angle of curvature, and radius of curvature in a custom-made cyclic fatigue testing device until the instrument fracture occurred. The time to fracture for each instrument was recorded with a stopwatch; in seconds in each group. Fractured instruments were subjected to atomic force microscopy analysis measuring the average roughness and the root mean square values to investigate surface features of endodontic files. Mean values and standard deviation were calculated. Data were analyzed using the Mann-Whitney U test. Results: Time to fracture was marginally higher in PTG instruments than in the TN file systems. PTG files exhibited higher surface roughness when compared with TN files (p<0.05). Conclusion: TN file system had a higher cyclic fatigue resistance than PTG. Cyclic fatigue causing file breakage did affect the surface topography of the files. PTG files showed a higher surface porosity value than the TN files (AU).

Microscopic morphology observation of fracture healing process promoted by panax notoginseng saponins / Observación microscópica de la morfología del proceso de curación de fracturas promovida por panax notoginseng saponins

SUMMARY: The aim of this study was to explore promoting effect of external applying Panax Notoginseng Saponins (PNS) on fractures. For this analysis 18 New Zealand male rabbits were divided into control group, splintage group and PNS group. All rabbits were performed left radius fractures and natural healing, splintage healing and splintage coated with PNS healing. 2 rabbits in each group were sacrificed on day 14, day 28 and day 42 after surgery, separately. Atomic force microscope scanning and nanoindentation tests were performed on the callus sections. The particle size and roughness in PNS group was both less than that in splintage group. The elastic modulus of callus in PNS group was consistent with normal bone tissue started from day 28 after surgery, two weeks earlier than that in splintage group. PNS could significantly reduce fracture healing time and increase strength of callus.

RESUMEN: El objetivo de este estudio fue evaluar el efecto de la aplicación externa de Panax Notoginseng Saponins (PNS) en fracturas óseas. Se usaron 18 conejos machos de raza Nueva Zelanda divididos en grupos control, entablillado y PNS. Se realizaron fracturas del radio izquierdo y cicatrización natural en todos los animales, además de la cicatrización con entablillado y entablillado recubierto con PNS. Se sacrificaron, posterior a la cirugía, dos conejos de cada grupo los día 14, 28 y 42. Se realizaron pruebas de escaneo con microscopio de fuerza atómica y nanoindentación en las secciones de callos. El tamaño de la partícula y la rugosidad en el grupo de PNS fue menor que en el grupo entablillado. El módulo elástico del callo en el grupo de PNS fue consistente con el tejido óseo normal iniciado el día 28 después de la cirugía, dos semanas antes que en el grupo de entablillado. El PNS podría redu- cir significativamente el tiempo de curación de la fractura y aumentar la fuerza del callo.

Bioconcentración de metales pesados (Zn, Hg, Pb) en tejidos de Ariopsis felis y Diplodus annularis en el río Ranchería, norte de Colombia / Bioconcentration of heavy metals (Zn, Hg, Pb) in tissues of Ariopsis felis and Diplodus annularis in the Ranchería river, Northern Colombia

RESUMEN La contaminación por metales pesados en los ecosistemas acuáticos en el planeta es una de las más severas problemáticas que comprometen la seguridad alimentaria a nivel local, regional y global. En este estudio, se aborda el problema específico de la bioconcentración de mercurio (Hg), plomo (Pb) y Zinc (Zn) en los tejidos orgánicos de 2 de las especies de peces (Ariopsis felis y Diplodus annularis) de mayor importancia alimenticia para los pobladores rivereños del río Ranchería, al norte de Colombia. Las muestras de tejido orgánico se sometieron a una digestión ácida (HNO3 y HClO 4 en relación 3:1) y la cuantificación de los metales se realizó por espectrofotometría de absorción atómica. Adicionalmente, se midieron los niveles de los metales en el sedimento, con el objeto de determinar índices de calidad medioambientales, lo que permitió determinar que los metales pesados no presentan riesgo para los organismos acuáticos que habitan en esta zona. Se encontraron diferentes valores de concentración de metales pesados: en orden decreciente, Zn > Hg > Pb, en sedimento, y Hg > Zn > Pb, en el tejido biológico. Los resultados muestran que las concentraciones de los metales pesados presentes en el tejido de los peces y en el sedimento guardan una correlación positiva y una regresión lineal estadísticamente significativa (p = 0,001, p < 0,05). La presencia de metales pesados en el sedimento del río y de bioconcentrados en los peces podría derivarse de fuentes puntuales y difusas relacionadas con actividades agrícolas, pecuarias, mineras y aguas residuales.

ABSTRACT Heavy metal pollution in aquatic ecosystems in the area is one of the most severe problems that compromise food security at the local, regional and global levels. In this study, the specific problem of the bioconcentration of mercury (Hg), lead (Pb), and Zinc (Zn) in 2 of the higher nutritional importance fish species (Ariopsis felis and Diplodus annularis) for the riverside inhabitants of the Ranchería river, in northern Colombia, is addressed. The organic tissue samples were subjected to acid digestion (HNO3 and HClO4 in a 3:1 ratio), and the quantification of metals was carried out by atomic absorption spectrophotometry. Additionally, the levels of metals in the sediment were measured, in order to determine environmental quality indices. This allow to determine that heavy metals do not present a risk to the aquatic organisms that inhabit this area. Different heavy metal concentration values were found: in decreasing order, Zn> Hg> Pb in sediment, and Hg> Zn> Pb in biological tissue. The results reveal that the concentrations of heavy metals present in fish tissue and sediment show a positive correlation, and a statistically significant linear regression (p = 0,001, p < 0,05). The presence of heavy metals in river sediment and bioconcentrates in fish could derive from point and diffuse sources related to agricultural, livestock, mining and wastewater activities.