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The microstructures and properties of two kinds of zirconium-enriched α alloys （Ti60Zr40）97Al3（mass fraction/%，the same below） and （Ti50Zr50）97Al3 via different heat treatments were investigated and analyzed based on optical microscope （OM） observation， differential scanning calorimetric （DSC） measurement， X-ray diffraction （XRD） measurement， scanning electron microscope （SEM） observation and tensile tests at room temperature.The results show that after 850 ℃/40 min annealing， microstructures consisting of basket-weave α phase and a small amount of reticular β phase are formed in the alloys. After 850 ℃/40 min quenching， the acicular α' martensite phase is formed. After 850 ℃/40 min quenching and then 600 ℃/4 h aging， a large part of α' martensite phase converts into α phase， and the microstructures of the alloys consist of α and α'remain phases. The yield strength of the T40Z3A alloy can reach 1100 MPa， with a favourable tensile elongation of 7%. The T50Z3A alloy exhibits higher strength but lower ductility than those of the T50Z3A alloy. Due to the higher content of Zr element， the T50Z3A alloy has more reticular β phase after annealing and more remaining α' martensite phase after quenching and aging， which results in higher strength and lower ductility.

ObjectiveThe coking problem of biomass in fluidized bed combustion process was studied, and the influence of potassium salt form and content on the sintering and melting characteristics of biomass ash was analyzed.MethodsThe sintering and melting characteristics and the mineral transformation law of synthetic biomass ash were analyzed by experiments with scanning electron microscope coupled energy dispersive spectrometer, X-ray diffractometer, X-ray fluorescence, and FactSage thermodynamic calculation software.ResultsIn the typical operating temperature range of 750-950 ℃, the sintering and melting degree of synthetic biomass ash aggravates with the increase of temperature and potassium salt mass fraction. In addition, the effects of different forms of potassium salt on the sintering and melting characteristics of biomass synthetic ash are also significantly different. When the potassium salt is in the form of K2CO3, the liquid phase in the synthetic ash could reach up to 34.36%, leading consequently to severe sintering of the ash. When the potassium salt is in the form of KCl, most of K and Cl elements escape at 750-850 ℃, and the sintering degree of synthetic ash is weakened in comparison with the K2CO3 situation. When the potassium salt is in the form of K2SO4, the liquid phase in the synthetic ash is the least, and the sintering and melting degree is also the weakest.ConclusionChanging the form of potassium salt and controlling the temperature of fluidized bed are expected to alleviate the coking problem of biomass in fluidized bed combustion.

Background In China, esophageal cancer is one of the most common cancers, and its incidence and mortality are more than twice the global average. However, most esophageal cancers in China are not detected until they are at moderate and advanced stages with poor prognosis, so early diagnosis and treatment are urgently needed. At present, the role of gut flora in the diagnosis and treatment of esophageal cancer has attracted much attention. Objective To explore the basic characteristics of gut flora in patients with esophageal squamous cell carcinoma. Methods From the Fourth Hospital of Hebei Medical University from April to August 2022, 35 patients with esophageal squamous cell carcinoma with no previous anti-cancer treatments were included as esophageal cancer group (EC group), and 35 healthy volunteers as control group. Stool samples of the two groups were collected to detect the gut flora using 16S rDNA sequence. Then an analysis was performed on the Alpha diversity, Beta diversity〔using the principal coordinate analysis (PCoA) 〕 and differential species of gut flora 〔using the linear discriminant analysis Effect Size (LEfSe) 〕 of two groups according to the species annotation of the test results. Results The Alpha diversity indices, such as Shannon index, Simpson index, Chao1 index, ACE index and Goods_coverage index demonstrated no significant differences between the two groups (P>0.05), while PCoA graph showed that the Beta diversity differed significantly between the two groups on the whole, and the community structures were different (t=10.837, P

In recent years, three-dimensional (3D) seismic base isolation system has been studied extensively. In order to study the application of 3D seismic base isolation in nuclear power plants (NPPs), the new 3D combined isolation bearing (3D-CIB) composed of laminated rubber bearing with lead-core coupled with combined disk spring bearing (CDSB) was proposed. Four different combinations of CDSB were designed and employed as the vertical isolation component, based on the advantage that the constitution of CDSB can be flexibly adjusted according to its bearing capacity and stiffness requirement. CDSB and laminated rubber bearing with lead-core were respectively connected in series to form four kinds of 3D-CIB with different vertical stiffnesses, which was firstly applied to isolate nuclear reactor building from both the horizontal and vertical components of seismic motion beneath the raft foundation. The influence of different vertical stiffnesses of 3D-CIB on the 3D isolation effectiveness was investigated. A comparative study of modal analysis in terms of main frequencies and mode shape, and the seismic response in terms of acceleration floor response spectra (FRS), acceleration and relative displacement response was carried out, respectively. The results show that the main frequencies of the 3D isolated nuclear reactor building for the degrees of freedom of both translation and torsion are significantly reduced compared with that of the non-isolated structure, and the first mode of the 3D isolated superstructure is not purely horizontal motion along the x-axis but a combination of rocking and horizontal motion. 3D-CIB can effectively reduce FRS and acceleration response in both the horizontal and vertical direction. Overall, the horizontal isolation effectiveness of 3D-CIB is less affected by vertical stiffness, and the smaller vertical stiffness of 3D-CIB, the better the vertical isolation effectiveness is, while the horizontal and vertical displacement response of superstructure increases correspondingly, including the rocking effect. The concept of rocking rate is introduced to quantitatively analyze the rocking effect, and the decrease in the vertical stiffness may significantly increase the rocking, which cannot be ignored. Hence, the vertical stiffness of 3D-CIB should be designed by properly accounting for the balance between the isolation effectiveness and displacement response. Besides, 3D-CIB always remains in a stable compressed state in the whole process of earthquake, so that the isolated superstructure has the stable robustness without risk of overturning. This study of 3D isolation effectiveness can provide the technical basis for the application of 3D-CIB into real engineering of NPPs in the future.

Objective To compare the disinfection effects of 500 mg/L chlorine-containing disinfectant and 3% hydrogen peroxide disinfectant applied to the threaded plastic hose at the fixed end of the saliva suction pipe of the oral comprehensive treatment table after diagnosis and treatment of patients in stomatology to provide a basis for clinical cleaning and disinfection. Methods The fixed ends of saliva suction pipes of 12 comprehensive treatment tables in the dental pulp department and maxillofacial surgery were selected as the research objects. The absorption was randomly divided into two groups and a control group: experimental group 1 with 500 mg/L chlorine disinfectants and experiment 2 group with 3% hydrogen peroxide disinfectant rinse disinfection and the control group with 0.9% sterile saline flushing pipe once a week for four weeks. Before and after washing and disinfection, samples from the inner wall of the threaded plastic hose interface were collected for bacterial culture and colony count, and colony counts within and between groups were compared before and after disinfection. Statistical analysis was conducted using SPSS 24.0 software. Results The baseline number of bacterial colonies in the first three groups was balanced, with no statistically significant difference (χ2 = 0.538, P = 0.764). The number of bacterial colonies after washing and disinfection was lower than that before washing and disinfection. The difference between 500 mg/L chlorine-containing disinfectant and 3% hydrogen peroxide disinfectant before and after disinfection was highly significant (Z = -4.801, P

AIM: To investigate the protective effect of total flavonoids from Patrina villosa Juss (PJF) on the lung in an experimental rat model of acute lung injury (ALI), and to elucidate the potential mechanism. METHODS: The ALI rat model was established by instilling 5 mg/kg of lipopolysaccharide (LPS) into the airway. Sixty male SD rats were randomly divided into 4 groups: control, LPS, LPS+low-dose PJF (receiving 100 mg/kg PJF one hour before ALI modeling) and LPS+high-dose PJF (receiving 300 mg/kg PJF one hour before ALI modeling). Each group consisted of 15 animals. Lung tissues and bronchoalveolar lavage fluid (BALF) were collected from all groups 24 h after modeling. For assessment of lung tissue morphology, HE staining was performed. The wet/dry weight ratio of the lung tissue was determined using the wet/dry weighing method. Evans blue staining was conducted to assess epithelial barrier permeability in lung tissues. ELISA was used to detect the levels of inflammatory factors tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and IL-6 in the BALF, as well as oxidative stress markers including superoxide dismutase (SOD), myeloperoxi-dase (MPO) and glutathione peroxidase (GSH-Px) activity, and malondialdehyde (MDA) content in the lung tissue. The expression levels of C/EBP homologous protein (CHOP), glucose-regulated protein 78 (GRP78) and X-box binding protein 1 (XBP1) in the lung tissue were analyzed by Western blotting. RESULTS: Compared with control group, the rats in LPS group exhibited a blurred alveolar structure with a significant infiltration of inflammatory cells. The ALI score and the wet/dry weight ratio of the lung tissue were increased (P<0. 05). Concurrently, the levels of IL-6, IL-1β and TNF-α in the BALF, along with MDA content and MPO activity in the lung tissue, were elevated (P<0. 05). Additionally, the protein levels of CHOP, GRP78 and XBP1 were up-regulated in the lung tissue (P<0. 05), while the SOD and GSH-Px activity was significantly decreased (P<0. 05). Compared with LPS group, PJF intervention exerted beneficial effects on the lung tissue morphology with reduced ALI score and lower lung wet/dry weight ratio (P<0. 05). Moreover, the levels of IL-6, IL-1β and TNF-α in BALF, as well as MDA content, MPO activity and the protein levels of CHOP, GRP78 and XBP1 in the lung tissue were all significantly decreased (P<0. 05), while the SOD and GSH-Px activity was significantly increased (P<0. 05). The efficacy in high-dose group exceeded that in low-dose group. CONCLUSION: The PJF have protective effect on the lungs of rats with ALI, and its mechanism may be related to the inhibition of inflammation, oxidative stress and endoplasmic reticulum stress. [ABSTRACT FROM AUTHOR]

Objective To investigate the oral health behavior of urban and rural students in the 12~15 year age group in Guangdong Province, aiming to provide informational support for adolescent oral health care. Methods A multistage stratified sampling method with equal capacity and simple random sampling was applied to obtain representative samples. A total of 7 680 students aged 12 to 15 were selected from Guangdong Province, with 1 920 in each age group of 12, 13, 14 and 15 years; half were male and half were female, and half were from urban areas and half were from rural areas. According to the Fourth National Oral Health Epidemiology Questionnaire Survey Program, a standard questionnaire was designed to conduct on-the-spot investigations on sugar intake, brushing, dental floss usage, fluoride toothpaste usage. Results ① Eating before a meal and before bed: the proportion of sweet snacks, sweet drinks and sugary drinks consumed ≥2 times/day was higher in the rural group than in the urban group (P < 0.001), with only sugary drinks consumed significantly differently by age (P < 0.001). ② The rural group had a significantly lower proportion of brushing ≥ 2 times/day, flossing habits and fluoride toothpaste habits than the urban group (P < 0.001), whereas only fluoride toothpaste habits were significantly different across age groups (P < 0.001). Conclusions Among the students aged 12 to 15 in Guangdong Province, the rural group had a higher proportion of consuming desserts, sweet drinks and sweetened drinks. The proportion of brushing ≥ 2 times/day was lower, and the usage rate of floss and fluoride toothpaste was lower.

Objective To investigate the expression of miR-127 in lung cancer and its effect on biological characteristics of lung cancer cells. Methods The lung cancer and adjacent tissues of 20 patients were collected, and the expression levels of miR-127 in lung cancer and adjacent tissues were detected by real-time polymerase chain reaction (PCR). A549 cell line were transfected with miR-127 mimics. The proliferation activity of lung cancer cells in miR-127 mimics group and negative control (NC) group were detected by cell colony formation assay and MTT assay. Transwell assay were performed to calculate the number of lung cancer cells passing through the membrane, and to analyze the relationship between miR-127 and the migration of lung cancer cells. Results The expression of miR-127 in lung cancer tissues was significantly lower than that in adjacent normal tissues (0.55±0.05 vs. 1.45±0.13, P=0.001). The expression of miR-127 in lung cancer tissues was decreased with the increased malignancy degree of pathological stage (H=6.528, P=0.034). The cell viability and proliferation of miR-127 mimics group were significantly inhibited (P=0.0032; P=0.0045). The number of lung cancer cells passing through the membrane in miR-127 mimics group was significantly lower than that in the NC group(79±18/field vs. 352±21/field, P=0.002). Conclusion The expression of miR-127 is decreased in lung cancer tissues, and it inhibits the proliferation and migration of lung cancer cells. It can be used as a potential clinical diagnostic marker for lung cancer, providing a new idea for early diagnosis and treatment of lung cancer.

Objective To understand the level and current status of oral health knowledge among people aged 35⁃44 years in Guangdong Province and to provide a reference for oral health education in Guangdong Province. Methods An equal⁃sized, stratified, multistage, random sampling design was applied to obtain representative sample groups consisting of 288 Guangdong residents aged 35⁃44 years in four urban areas and four rural areas with a gender ratio of one to one. According to the Guideline of the 4th National Oral Health Survey, a questionnaire survey was conducted, and a statistical analysis of the questionnaire responses related to oral health knowledge was performed. Results In total, 288 people participated in the survey, of which 95.8 percent were aware that“Oral health is very important to their own lives, and the prevention of oral diseases depends on themselves first” , 76.0% recognized that“Regular oral examination is very necessary” , and 66.7% disagreed that“Teeth were innate and had little to do with their own protection” . The percentages of participants that agreed with the statements“Eating sugar can cause dental caries” ,“Oral disease may affect general health” ,“Bacteria may cause dental caries”and“Bacteria may cause gum inflammation”were 87.2% , 84.7%, 80.9%, and 80.2%, respectively. However, the rates of awareness that teeth could be protected by fluoride and by pit and fissure sealant were only 36.8% and 18.8%, respectively. Conclusion General knowledge of oral health care was relatively high among adults aged 35 ⁃ 44 years in Guangdong Province, but knowledge of fluoride, pit and fissure sealing and caries prevention was relatively low. Oral health education should be continuously improved, especially regarding the popularization of oral health knowledge.

Based on the density functional theory simulation method, the adsorption behaviors of four typical mine gases (CO, CO2, CH4 and N2) on the surface oxygen-containing functional groups of coal are simulated from the atomic level. The adsorption mechanism of four kinds of gases on coal surface functional groups is investigated. Four kinds of gases simulate the adsorption behavior of six common functional group structural units on the coal surface: phenolic hydroxyl group, carboxyl group, carbonyl group, ether bond, alcoholic hydroxyl group and alkyl group. The results show that the adsorption energy, adsorption configuration and frontier orbit are calculated and analyzed. The adsorption strength of coal and four gases exists: CO2>N2>CO>CH4, and the order of adsorption of oxygen-containing functional groups on each coal surface model is: carboxyl group> alcoholic hydroxyl group> phenolic hydroxyl group> carbonyl group> Ether bond > alkyl group.

Objective To investigate the dental fluorosis status of permanent teeth of a 12⁃year⁃old population of Guangdong Province to provide informational support for oral health care in Guangdong. Methods An equal ⁃ sized cross⁃sectional random⁃sample assessment was carried out among 1 920 urban and rural residents of Guangdong Prov⁃ ince, half male and half female, aged 12 years. We examined the dental fluorosis status of complete permanent teeth crown based on a health survey and the criteria of clinical dental fluorosis from the fourth national oral health survey. The data were analyzed by SAS9.2 to investigate the prevalence and community fluorosis index as well as gender and ur⁃ ban and rural differences, and compared with the prevalence of fluorosis in Guangdong Province in 2005 and 1995. Re⁃ sults In the 12⁃year⁃old population, the prevalence of dental fluorosis was 5.05%, and the community fluorosis index was 0.108. There was no significant difference between genders（P > 0.05）, but there was a significant difference be⁃ tween subjects from urban and rural areas（P < 0.05）. There were significant differences among prevalence of dental flu⁃ orosis and community fluorosis index in 1995, 2005 and 2015—2016（P < 0.05）. Conclusion The prevalence of den⁃tal fluorosis and the community fluorosis index of 12 ⁃ year ⁃ old people of Guangdong Province are relatively low, but there is an upward trend.

Objective To investigate the current status of gingival bleeding and dental calculus in the 12⁃ to 74⁃ year old population in Guangdong Province with the aim of providing information to support oral health care. Methods A stratified, multistage, random sampling design was used to obtain 7 provincially representative sample groups consist⁃ing of 8, 544 Guangdong residents aged 12, 13, 14, 15, 35⁃44, 55⁃64 and 65⁃74 years old with a 50/50 gender ratio. The status of gingival bleeding and dental calculus in the whole mouth was assessed according to the Guidelines of the Fourth National Oral Health Survey using a CPI probe. The resulting data were analyzed using the SAS9.2 package. Results The prevalence of gingival bleeding in residents aged 12, 13, 14, 15, 35⁃44, 55⁃64 and 65⁃74 years old was 43.75%, 42.76%, 49.06%, 39.38%, 81.94%, 90.97%, and 84.03%, respectively, while the average number of teeth with gingival bleeding per person was 1.95, 2.07, 2.59, 2.39, 9.62, 10.36, and 9.98, respectively. In the 12⁃, 13⁃, 14⁃, and 15⁃ year⁃old groups, peak prevalence was observed at age 14 (P < 0.05). In the 35⁃74⁃year⁃old group, the prevalence and mean number of teeth with gingival bleeding per person increased with age, and both parameters reached a peak in the 55⁃64⁃year⁃old group. The prevalence of dental calculus in the 12⁃, 13⁃, 14⁃, 15⁃, 35⁃44⁃, 55⁃64⁃ and 65⁃74⁃year⁃old group was 40.57%, 41.09%, 45.05%, 54.84%, 98.96%, 97.22%, and 92.01%, respectively, and on average, each person had 1.61, 1.71, 2.14, 3.52, 20.30, 20.55, and 17.26 teeth, respectively, with dental calculus. The prevalence and mean number of teeth with dental calculus increased with age. In the 35⁃ to 74⁃ year⁃old group, the prevalence of dental calcu⁃ lus was higher in urban areas than in rural areas and the mean number of teeth with dental calculus was higher in males than in females. Otherwise, there were no significant differences in the prevalence or the mean number of teeth with den⁃ tal calculus or gingival bleeding between urban and rural areas or between males and females. Conclusion There is a high prevalence of both gingival bleeding and dental calculus in all 7 age groups in Guangdong, indicating that poor oral hygiene and gingival inflammation are common in Guangdong Province.

Obiective To investigate the current status of remaining teeth and edentulous jaw arch of people aged 35⁃44, 55⁃64 and 65⁃ 74 in Guangdong province. Methods An equal⁃ sized stratified multi⁃stage randomly sampling design was applied to select a total of 288 Guangdong residents in urban and rural areas, and the subjects were between the age of 35⁃44, 55⁃64 and 65⁃74, with a gender ratio of half to half. The status of remaining teeth and edentulous jaw arch were assessed according to the Guideline for the 4th National Oral Health Survey. Results 88.89% subjects in the 35⁃44 year group had more than 28 teeth and 100% subjects had more than 20 teeth, with an average of 29.88 teeth remaining and no edentulous jaw. The average remaining teeth was 26.06 in the group of 55 ⁃ 64 year, with 87.50% subjects having more than 20 teeth, 59.03% subjects having 28 or more teeth, 4.16% subjects having single edentulous jaw arch, and 1.04% subjects having both edentulous jaw arch. 73.96% and 35.07% subjects in the group of 65⁃74 year had 20 above or 28 above remaining teeth, respectively, and the average teeth was 22.94. There were 8.34% subjects having single edentulous jaw arch and 1.39% subjects having both edentulous jaws. In the 35⁃44 and 65⁃74 year group, the prevalence of missing teeth in the female was significantly higher than the male (P < 0.05), while no significant difference was found between urban and rural areas (P > 0.05). More remaining teeth were noticed in current survey (2015) when compared to the data in 2005 (P < 0.05). Conclusion The 35⁃44 year people have few lost teeth, and over half of the elderly people have several lost teeth. Elderly people with edentulous arch are very few.

Objective To investigate current status of periodontal health in the population at the age of 15⁃74 in Guangdong province and provide information for oral health care in Guangdong. Methods A stratified multistage randomly sampling design was applied to obtain 4 provincially representative sample groups consisted of 2784 Guangdong residents, aged at 15, 35⁃44, 55⁃64 and 65⁃74 respectively, with a gender ratio of half to half. The status of probing depth (PD) and loss of attachment (LOA) of the whole mouth were assessed according to the Guideline for the fourth National Oral Health Survey by using a CPI probe, and the data obtained were analyzed with SAS9.2 package. Results The prevalence of shallow periodontal pocket in the 15, 35⁃44, 55⁃64 and 65⁃74 years old group were 0.52%, 38.54%, 49.65%, 47.22% with 0.02, 2.05, 3.74, 2.80 affected teeth on average. The corresponding percentages of deep periodontal pocket in the 4 groups were 0.05%, 3.47%, 15.97%, 9.03% with 0, 0.07, 0.31, 0.16 affected teeth on average. Prevalence and the mean affected teeth of 4⁃5 mm LOA were 0.10%, 26.74%, 33.68%, 35.07% and 0, 1.54, 4.33, 4.05. The prevalence and the mean affected teeth of 6⁃8 mm LOA were 0, 6.94%, 32.29%, 27.08% and 0, 0.24, 1.23, 0.97. The prevalence of LOA≥4 mm were 0.10%, 35.07%, 79.17%, 74.65% and the prevalence of LOA≥6 mm were 0, 8.33%, 45.49%, 39.58%. In the 35⁃74 years old group, the prevalence and the mean teeth with PD and LOA increased with age and reached a peak in 55⁃64 years old group (P < 0.05). There were no significant differences in the prevalence and the mean teeth of PD and LOA between urban and rural areas. The mean teeth of PD in 35⁃44 and 55⁃64 years old groups were significant higher in the male than the female. The prevalence and the mean teeth with LOA were both significant higher in the male than the female. Conclusion The periodontal diseases indications are common in 35⁃74 years old people and most necessary at the age of 55⁃64 in Guangdong. The periodontal health may have extensive influence on oral health status in the middle⁃aged and the elder population in Guangdong.

Objective To explore the dental deciduous teeth caries among 3⁃5⁃ year ⁃ old children in Guangdong Province and to provide information support for oral health care of Guangdong Province. Methods A cross⁃sectional survey was carried out among 2 592 urban and rural residents in Guangdong. Subjects were from three different age groups (aged 3, 4 and 5), with 864 children in each group. Male and female were 1∶1 in each group. An equal sized sampling with stratified multistage method was used. According to the criteria of clinical dentition examination of the fourth national oral health survey, the dental caries in deciduous teeth were recorded using CPI probe. And then the prevalence, the mean dmft (decayed ⁃missing ⁃filled tooth), the filled rate were calculated. Results The prevalence of dental caries in deciduous teeth in the three groups of aged 3, aged 4, aged 5 were 58.33%, 68.40%, and 78.47% inde⁃ pendently; the mean dmft were 3.03, 4.34, and 5.69 independently; the filled rate were 0.92%, 1.47%, 1.26% indepen⁃ dently. There were significant differences in the prevalence and the mean dmft between urban and rural areas and among different age groups. There was no significant difference in the prevalence regarding the gender in each group, The mean dmft in the group of aged 3 in female were higher than that in male, while no gender differences were found in the groups of aged 4 and aged 5. The prevalence and the mean dmft of 5⁃year⁃old children were higher than that in 2005. Conclusion The 3⁃5⁃year⁃old children of Guangdong Province had a really high prevalence of dental caries in deciduous teeth. More than 98% of the caries are unfilled, treatment need is extremely huge. The 3⁃5⁃year⁃old children are the main target for us to prevent the early childhood caries.

Objective To explore the caries status of permanent teeth among 12⁃15⁃year⁃old population in Guang⁃ dong Province, and to provide information support for oral health care. Methods A cross⁃sectional survey was carried out among 7 680 urban and rural residents in Guangdong Province. Subjects were from four different age groups (aged 12, 13, 14 and 15), with 1 920 people in each group. An equal⁃sized stratified multistage randomly sampling was used, with a gender ratio of half to half in each group. According to the criteria of clinical dentition examination of the fourth national oral health survey, the crown caries of permanent teeth in the whole mouth were recorded using CPI probe. And then the prevalence, the mean DMFT (decayed⁃missing⁃filled tooth), the filled rate were calculated. Results The preva⁃ lence of crown caries in the groups of aged 12, aged 13, aged 14, aged 15 were 43.07%, 45.31%, 49.69%, 52.86%, re⁃ spectively. The mean DMFTs were 1.06, 1.13, 1.38, 1.59, respectively. The filled rates were 20.19%, 21.50%, 22.86%, 21.33%, respectively. The prevalence and the mean DMFT increased with age (P < 0.001), and both were higher than that in 2005. There were significant differences in the prevalence and the mean DMFT between urban and rural areas and between male and female (P < 0.001). Conclusion According to the criteria of the mean DMFT in 12⁃year ⁃old population of WHO, the severity of caries of permanent teeth in Guangdong was regarded as "very low". But the severity was higher than that in 2005, and the filled rate was low.

As for the smooth problems in the conjugate surface arising from hob tooth root and flank arc edge during the processing of new double helical synchronous belt’s pulley,the broken line generation mechanism at the conjugate tooth profile was investigated with spatial differential geometry and meshing theory. Through the undercut boundary curve characteristics analysis of the hob tooth profile surface,the parameter constraint conditions used to eliminate the pulley surface singularity was determined,and the eliminating profile singularity modification method by increasing the transition arc curve slope face on the hob tooth profile was proposed. Then the tooth profile hob practice model with undercutting constraints was built. The timing belt pulley’s hob tooth normal face profile parameters after modification was obtained based on coupling analysis of the modification pulley profile and double helical synchronous belt. The simulation shows that the pulley profile’s top curve after modification is smooth,it can reduce the abrasion during the meshing process and provide a useful modification method to improve the surface smoothness of the tooth belt.

BackgroundDNA (DeoxyriboNucleic Acid) polyhedral structure has great potential in molecular imaging probe with good properties in model animals such as low toxicity, low immunogenicity and excellent in vivo stability.PurposeThis article aims to use positron emission computed tomography (PET) radionuclide 64Cu to label DNA single strands instead of SPECT radionuclide 99mTc, and to study the distribution and metabolism of 64Cu labeled DNA single strands in Kunming mice in vivo.MethodsSingle strand DNA (ssDNA) was coupled with chelating agent p-SCN-Bn-NOTA and incubated with 64Cu for a certain time to obtain NOTA-ssDNA. The labeling reaction was monitored by thin layer chromatography, and purified by NAP-5 desalting column to obtain 64Cu-ssDNA. After injection into Kunming mice, the radioactive uptakes of organs of interest at different time were studied.ResultsAfter NOTA-ssDNA reacted with 64Cu for 1 h, the radiochemical labeling rate is (66.4±2.85)%. After purification, the radiochemical purity is >95%. The in vitro stability experiments show that 64Cu-ssDNA can stably exist in PBS and mouse serum for at least 6 h. There was a certain uptake in the gastrointestinal tract and high radioactive uptake in both the kidney and bladder after 64Cu-ssDNA is injected into the mice, indicating that 64Cu-ssDNA is mainly excreted through the urinary system.ConclusionsSuccessful preparation of 64Cu-ssDNA is a critical step for the preparation of PET molecular probes based on DNA polyhedral. In vivo distribution experiment provides experimental control data for studying the in vivo biological distribution of 64Cu labeled DNA polyhedra.

The epidemic of coronavirus disease 2019 (COVID-19) puts higher demands on critical care medicine. Lots of studies have been conducted to solve COVID-19-related problems. Therefore, we reviewed the annual progress for COVID-19-related issues including antivirals threapies, respiratory support and immunomodulatory therapies and other critical issues, including the effect of antibiotic on mitochondrial damage and its relationship with sepsis, the goal and direction of antimicrobial de-escalation, drug prophylaxis of constipation, bleeding in gastrointestinal disorders and management of critical illness in the informalization era and so on. We hope to provide reference for clinical and scientific research work of the intensivists.

HPV16 L2E7 is a fusion protein used for therapeutical vaccine targeting HPV virus. To increase its expression in Escherichia coli, we optimized the codon usage of HPV16 l2e7 gene based on its codon usage bias. The optimized gene of HPV16 sl2e7 was cloned into three different vectors: pGEX-5X-1, pQE30, ET41a, and expressed in JM109, JM109 (DE3) and BL21 (DE3) lines separately. A high expression line was selected with pET41a vector in BL21 (DE3) cells. After optimization of the growth condition, including inoculation amount, IPTG concentration, induction time and temperature, the expression level of HPV16 L2E7 was increased from less than 10% to about 28% of total protein. HPV16 L2E7 protein was then purified from 15 L culture by means of SP Sepharose Fast Flow, Q Sepharose Fast Flow and Superdex 200 pg. After renaturing, HPV16 L2E7 protein with ≥ 95% purity was achieved, which was confirmed via SDS-PAGE gel and Western blotting. The combined use of purified HPV16 L2E7 and CpG helper has shown clear inhibition of tumor growth in mice injected with tumor cells, with six out of eight mice shown no sign of tumor. This study lays a solid foundation for a new pipeline of large-scale vaccine production.

A solid phase extraction (SPE) and gas chromatography (GC) with mass spectrometry (MS) method for determination of ethyl glucuronide (EtG) in human urine was established. One mL urine sample was deproteinated by 100 microL 3 mol/L hydrochloric acid and cleaned up through a solid phase extraction column. The target analytes were eluted from an NH2-column with 4% ammonia solution and then treated with bis (trimethylsilyl) trifluoroacetamide (BSTFA) + trimethylchlorosilane (TMCS) (99:1) for derivatization. The derivatized samples were analyzed by GC-MS. Data were acquired in the selected ion monitoring (SIM) mode and the quantitation of EtG was done through internal standard method. Good linearity was obtained at the mass concentration range of 0.1 - 3.2 mg/L with a correlation coefficient (r) of 0.9921. The limit of detection (LOD) was 28.4 microg/L. The range of recoveries was 92.5% - 108.7%, and the relative standard deviations (RSDs) of intra-day and inter-day were all less than 5%. This method is sensitive, specific, accurate and can be applied to the determination of EtG for medicolegal identification and clinical laboratory.