Comparison of Growth and Development Patterns of Fenneropenaeus chinensis (Osbeck) Huanghai No.1 and the First Generation of Wild Population

[Objective] The aim was to estimate the developmental characteristics of Huanghai No.1 and the first generation of wild population in Fenneropenaeus chinensis for providing a reference for the development, feeding management and breeding. [Method] Four growth models were used to fit the growth patterns of 15 morphological traits. The squared multiple correlation coefficient (R2 ) of the Cubic growth model was higher than the other three models, so it was selected to investigate the growth pattern and age in month at inflexion. [Result] Ages in month at inflexion of body weight in Huanghai No.1 and the G1 population were 2.87 (body weight at inflexion was 14.98 g) and 4.05 (body weight at inflexion was 26.26 g), respectively. In addition, Ages in month at inflexion of morphological characters in Huanghai No.1 were from 0.51 to 3.07. CL had the most rapid growth rate, followed by AW, CH, AH, CW, BL, FL, AL5, AL3, AL4, TL, AL2, AL1, and AL6. Ages in month at inflexion in the G 1 population were from 2.38 to 3.08, except that of AL2, and the order of achieving the most rapid growth rate was AL2, AL1, AL3, AL4, CH, AL5, CW, FL, AH, AW, TL, CL, BL, and AL6, that delayed one month than that of Huanghai No.1 except AL2 and AL1. [Conclusion] The development of Huanghai No.1 cultivar was advanced for about one month compared to that of the G1 population.

Designing new low alloyed Mg-RE alloys with high strength and ductility via high-speed extrusion

Two new low-alloyed Mg-2RE-0.8Mn-0.6Ca-0.5Zn(wt%,RE=Sm or Y)alloys are developed,which can be produced on an in-dustrial scale via relatively high-speed extrusion.These two alloys are not only comparable to commercial AZ31 alloy in extrudability,but also have superior mechanical properties,especially in terms of yield strength(YS).The excellent extrudability is related to less coarse second-phase particles and high initial melting point of the two as-cast alloys.The high strength-ductility mainly comes from the formation of fine grains,nano-spaced submicron/nano precipitates,and weak texture.Moreover,it is worth noting that the YS of the two alloys can maintain above 160 MPa at elevated temperature of 250°C,significantly higher than that of AZ31 alloy(YS:45 MPa).The Zn/Ca solute segregation at grain boundaries,the improved heat resistance of matrix due to addition of RE,and the high melting points of strengthening particles(Mn,MgZn_(2),and Mg-Zn-RE/Mg-Zn-RE-Ca)are mainly responsible for the excellent high-temperature strength.

Developing new Mg alloy as potential bone repair material via constructing weak anode nano-lamellar structure

The mechanics-corrosion and strength-ductility tradeoffs of magnesium(Mg)alloys have limited their applications in fields such as orthopedic implants.Herein,a fine-grain structure consisting of weak anodic nano-lamellar solute-enriched stacking faults(SESFs)with the average thickness of 8 nm and spacing of 16 nm is constructed in an as-extruded Mg96.9Y1.2Ho1.2Zn0.6Zr0.1(at.%)alloy,obtaining a high yield strength(YS)of 370 MPa,an excellent elongation(EL)of 17%,and a low corrosion rate of 0.30 mm y−1(close to that of high-pure Mg)in a uniform corrosion mode.Through scanning Kelvin probe force microscopy(SKPFM),one-dimensional nanostructured SESFs are identified as the weak anode(∼24 mV)for the first time.The excellent corrosion resistance is mainly related to the weak anodic nature of SESFs and their nano-lamellar structure,leading to the more uniform potential distribution to weaken galvanic corrosion and the release of abundant Y^(3+)/Ho^(3+)from SESFs to form a more protective film with an outer Ca_(10)(PO_(4))_(6)(OH)_(2)/Y_(2)O_(3)/Ho_(2)O_(3) layer(thickness percentage of this layer:72.45%).For comparison,the as-cast alloy containing block 18R long period stacking ordered(LPSO)phase and the heat-treated alloy with fine lamellar 18R-LPSO phase(thickness:80 nm,spacing:120 nm)are also studied,and the characteristics of SESFs and 18R-LPSO phase,such as the weak anode nature of the former and the cathode nature of the latter(37-90 mV),are distinguished under the same alloy composition.Ultimately,we put forward the idea of designing Mg alloys with high mechanical and anti-corrosion properties by constructing"homogeneous potential strengthening microstructure",such as the weak anode nano-lamellar SESFs structure.

A Class of Nonautonomous Schistosomiasis Transmission Model with Incubation Period

A nonautonomous schistosomiasis model with latent period and saturated incidence is investigated. Further, we study the long-time behavior of the epidemic model. The weaker sufficient conditions for the permanence and extinction of infectious population of the model are obtained by constructing some auxiliary functions. Numerical simulations show agreement with the theoretical results.

The Survey of Birth Defects Rate Based on Birth Registration System

Background：To investigate the surveillance trend of birth defects,incidence,distribution,occurrence regularity,and their relevant factors in Xi＇an City in the last 10 years for proposing control measures.Methods：The birth defects monitoring data of infants during perinatal period （28 weeks of gestation to 7 days after birth） were collected from obstetrics departments of all hospitals during 2003-2012.Microsoft Excel 2003 was used for data input,and Statistical Package for the Social Sciences version 16.0 （International Business Machines Corporation,New York,NY,USA） was used for descriptive analysis.χ^2 test,Spearman correlation and linear-by-linear association trend test were used for statistical analyses.Results：The birth defect rate declined from 9.18% in 2003 to 7.00% in 2012 （χ^2 =45.001,P 〈 0.01） with a mean value of 7.85%,which is below the Chinese national average level （χ^2 =20.451,P 〈 0.01）.The order of five most common birth defects has changed.The incidence of congenital heart disease （CHD） increased with time,particularly after 2012,it became the most frequent type （rs =0.808,P 〈 0.001）.Till then,the number of neural tube defects （NTDs） declined significantly （χ^2 =76.254,P 〈 0.01）.The average birth defects rate of 8.11% in rural areas was higher than that in urban areas （7.56%,χ^2 =7.919,P 〈 0.01） and much higher in males （8.28%） than that in females （7.18%,χ^2 =32.397,P 〈 0.0 1）.Maternal age older than 35 years （χ^2 =35.298,P 〈 0.01） is the most dangerous age bracket of birth defects than maternal age younger than 20 years （χ^2 =7.128,P 〈 0.0l）.Conclusions：A downward trend of birth defects was observed in Xi＇an City from 2003 to 2012.NTDs significantly decreased after large-scale supplemental folic acid intervention,while the incidence rate of CHD significantly increased.

Photochemistry of hypocrellin derivatives under anaerobic conditions

To improve the red absorption and solubility of hypocrellin, we have synthesized a series of hypocrellin B derivatives. The pnotochemistry of these new compounds in anaerobic media has been investigated by using electronic paramagnetic resonance (EPR) and spectrophotometric methods. The semiquinone anion radicals can be produced by self-electron transfer on irradiation, with the formation efficiency and EPR hyperfine structures of the semiquinone anion radicals dependent on the structures of the derivatives. When an electron donor is present, the electron transfer from electron donor to hypocrellin B derivatives enhanced the production of the corresponding semiquinone anion radical; in addition, the semiquinone anion radical and hydroquinone can be detected spectrophotometrically. Structural modifications exert little effect on the absorption position of semiquinone anion radical and hydroquinone, but influence their formation efficiency significantly.

Photophysics,photochemistry and photobiology of hypocrel-lin photosensitizers

Hypocrellins are novel photosensitizers from China, which are demonstrated to have significant anti-tumor and anti-virus activity and to be potential photo-dynamic therapy (PDT) agents. As compared with hemato-porphyrin, the only approved photosensitizer, hypocrellins have several advantages, such as easy preparation and easy purification, high triplet quantum yield, high singlet-oxygen quantum yield, high phototoxicity but low dark toxicity, and rapid clearance from normal issues. This article reviews briefly the photophysics, photochemistry and photobiology of hypocrellins on the basis of the domestic and international research results.

The Impact of COVID-19 Epidemic on Tuberculosis Reports Among Students — Guizhou Province, China, 2020

Summary What is already known about this topic?In 2020,the implementation of non-medical interventions during the coronavirus disease 2019(COVID-19)epidemic has created a negative impact on tuberculosis(TB)control.It is unclear if the prevalence of TB among students in Guizhou Province was also affected.What is added by this report?Among TB cases,the proportion of student TB patients was 19.91%in the back-to-school period in 2020,which was higher than the 13.37%registered in 2017–2019,but this decreased in the COVID-19 pandemic period.The time interval between symptom onset and care-seeking of the student TB patients was the shortest in the back-to-school and physical checkup periods.What are the implications for public health practice?TB active screening was effective for timely detection and diagnosis of TB among students,which could prevent TB outbreaks in schools.

Photochemistry of hypocrellin derivatives under aerobic conditions

Hypocrellins are a novel type of photosensitizers. A series of new hypocrellin B (HB) derivatives have been synthesized to overcome their limitations, i.e. to improve their red absorption and amphiphilicity. The generation of reactive oxygen species (including superoxide anion radical, hydroxyl radical and singlet oxygen) is investigated in the presence of oxygen. The chemical structures of HB derivatives affect not only the generation efficiencies of superoxide and hydroxyl radicals, but also quantum yields of singlet oxygen.

Epidemiological Characteristics of Rifampicin-Resistant Tuberculosis in Students——China,2015-2019

Summary What is already known about this topic?The number of students with tuberculosis(TB)has been increasing since 2015.However,the prevalence of rifampicin-resistant tuberculosis(RR-TB)among student population is unclear.What is added by the report?The number of students with RR-TB has significantly increased from 2015 to 2019,especially in the western region of China.The majority of patients were college students.Students with RR-TB were mainly new patients.