[Safety evaluation of simultaneous administration of quadrivalent influenza split virion vaccine and 23-valent pneumococcal polysaccharide vaccine in adults aged 60 years and older]

Objective: To evaluate the safety of simultaneous administration of quadrivalent influenza split virion vaccine and 23-valent pneumococcal polysaccharide vaccine in adults aged 60 years and older. Methods: From November 2021 to May 2022, eligible participants aged 60 years and older were recruited in Taizhou City, Jiangsu Province, China, and a total of 2 461 participants were ultimately enrolled in this study. Each participant simultaneously received one dose of quadrivalent influenza split virion vaccine and one dose of 23-valent pneumococcal polysaccharide vaccine. The safety was observed within 28 days after vaccination. Safety information was collected through voluntary reporting and regular follow-ups. Results: All 2 461 participants completed the simultaneous administration of both vaccines and the safety follow-ups for 28 days after vaccination. The mean age of the participants was (70.66±6.18) years, with 54.61% (1 344) being male, and all participants were Han Chinese residents. About 22.51% (554) of the participants had underlying medical conditions. The overall incidence of adverse reactions within 0-28 days after simultaneous vaccination was 2.07% (51/2 461), mainly consisting of Grade 1 adverse reactions [1.83% (45/2 461)], with no reports of Grade 4 or higher adverse reactions or vaccine-related serious adverse events. The incidence of local adverse reactions was 0.98% (24/2 461), primarily presenting as pain at the injection site [0.93% (23/2 461)]. The incidence of systemic adverse reactions was 1.42% (35/2 461), with fever [0.85% (21/2 461)] being the main symptom. In the group with underlying medical conditions and the healthy group, their overall incidence of adverse reactions was 2.53% (14/554) and 1.94% (37/1 907), respectively. The incidence of local adverse reactions in the two groups was 1.62% (9/554) and 0.79% (15/1 907), respectively, and the incidence of systemic adverse reactions was 1.44% (8/554) and 1.42% (27/1 907), respectively, with no statistically significant differences between them (all P>0.05). Conclusion: It is safe for adults aged 60 years and older to receive quadrivalent influenza split virion vaccine and 23-valent pneumococcal polysaccharide vaccine at the same time.

[Feasibility and safety of transseptal transcatheter mitral valve replacement for severe mitral regurgitation]

A prospective, single-center, single-arm, and open-design study was performed to evaluate the feasibility and safety of transseptal transcatheter mitral valve replacement in the treatment of severe mitral regurgitation. Patients with symptomatic moderate-severe or severe mitral regurgitation at high-surgical risk and anatomically appropriate for the HighLife transseptal mitral valve replacement (TSMVR) system in West China Hospital, Sichuan University from December 2021 to August 2022 were enrolled. Four patients (1 male and 3 females) with severe mitral regurgitation were included, with a median age of 68.5 (64.0-77.0) years and a median Society of Thoracic Surgeons (STS) score of 8.1% (6.4%-8.9%). Technical success was achieved in all the patients. There was no residual mitral regurgitation, paravalvular leakage, or left ventricular outflow tract obstruction. Three major cardiovascular and cerebrovascular adverse events occurred within 30 days after the procedure, including ventricular tachycardia, iatrogenic atrial septal defect closure, and heart failure readmission. The current study preliminarily demonstrates that transcatheter mitral valve replacement using the HighLife system via the transseptal approach for severe mitral regurgitation is feasible and relatively safe.

[Epidemiological characteristics and risk factors of sepsis development and death in patients with extremely severe burns]

Objective: To explore the epidemiological characteristics and risk factors of sepsis development and death in patients with extremely severe burns. Methods: A retrospective case series study was conducted. From January 2017 to December 2021, 135 patients with extremely severe burns who met the inclusion criteria were admitted to the Department of Burn and Wound Repair of the Second Affiliated Hospital of Zhejiang University School of Medicine, including 100 males and 35 females, aged 18-84 years. The incidence and diagnosis time of sepsis, the rate of positive microbial culture of blood samples (hereinafter referred to as positive blood culture), and the mortality rate of all patients, as well as the incidence of sepsis and the pathogen of infection in patients with positive blood culture were recorded (statistically analyzed with chi-square test or Fisher's exact probability test). According to the occurrence of sepsis, all patients were divided into sepsis group (58 cases) and non-sepsis group (77 cases), and the gender, age, body mass index, history of hypertension, history of diabetes, combination of inhalation injury, burn site, burn type, total burn area, and combined injury of patients were compared between the two groups. According to the outcome, all patients were divided into death group (37 cases) and survival group (98 cases), and the aforementioned data grouped according to sepsis as well as the stability of shock period and the combination of sepsis of patients were compared between the two groups. The aforementioned data between two groups were statistically analyzed with univariate analysis of independent sample t test, Wilcoxon rank-sum test, Mann-Whitney U test, chi-square test, or Fisher's exact probability test. Factors with P<0.1 were selected for multivariate logistic regression analysis to screen independent risk factors of sepsis and death in patients with extremely severe burns. Results: Among all patients, the incidence of sepsis was 42.96% (58/135), the diagnosis time of sepsis was 14 (7, 24) d after injury, the positive blood culture rate was 62.22% (84/135), and the mortality rate was 27.41% (37/135). The incidence of sepsis of patients with positive blood culture was 69.05% (58/84). The top 5 pathogenic bacteria in the detection rate of septic patients with positive blood culture were Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterobacter cloacae, ranking from high to low, and the proportion of Acinetobacter baumannii infected was significantly higher than that of non-septic patients with positive blood culture (χ2=7.49, P<0.05). Compared with those in non-sepsis group, the proportion of combination of inhalation injury, the proportion of perineal burns, and the total burn area of patients in sepsis group increased significantly (with χ2 values of 11.08 and 17.47, respectively, Z=5.68, P<0.05), while the other indicators did not change significantly (P>0.05). Multivariate logistic regression analysis showed that combination of inhalation injury, total burn area ≥80% total body surface area (TBSA), and perineal burns were independent risk factors for patients with extremely severe burns developing sepsis (with odds ratios of 3.15, 7.24, and 3.24, respectively, with 95% confidence intervals of 1.07 to 9.29, 1.79 to 29.34, and 1.21 to 8.68, respectively, P<0.05). Compared with those in survival group, the proportion of combination of inhalation injury, the proportion of perineal burns, and the proportion of combination of sepsis (with χ2 values of 6.55, 11.64, and 22.26, respectively, P values all <0.05), total burn area (Z=4.25, P<0.05), and proportion of instability of shock period (P<0.05) of patients in death group all increased significantly, while the other indicators did not change significantly (P>0.05). Multivariate logistic regression analysis showed that the instability of shock period and combination of sepsis were independent risk factors for death of patients with extremely severe burns (with odds ratios of 4.87 and 3.45, respectively, with 95% confidence intervals of 1.21 to 19.57 and 1.28 to 9.33, respectively, P<0.05). Conclusions: Patients with extremely severe burns have a high incidence of sepsis and a high mortality rate. The peak period of sepsis onset is 2 weeks after injury, with Acinetobacter baumannii as the most prominent infectious pathogen. Combination of inhalation injury, total burn area ≥80% TBSA, and perineal burns are independent risk factors for extremely severe burn patients complicated with sepsis, and combination of sepsis and instability of shock period are independent risk factors for death of patients with extremely severe burns.

[Effects of three-dimensional bioprinting antibacterial hydrogel on full-thickness skin defect wounds in rats]

Objective: To explore the effects of three-dimensional (3D) bioprinting gelatin methacrylamide (GelMA) hydrogel loaded with nano silver on full-thickness skin defect wounds in rats. Methods: The experimental research method was adopted. The morphology, particle diameter, and distribution of silver nanoparticles in nano silver solution with different mass concentrations and the pore structure of silver-containing GelMA hydrogel with different final mass fractions of GelMA were observed by scanning electron microscope and the pore size was calculated. On treatment day 1, 3, 7, and 14, the concentration of nano silver released from the hydrogel containing GelMA with final mass fraction of 15% and nano silver with final mass concentration of 10 mg/L was detected by mass spectrometer. At 24 h of culture, the diameters of inhibition zone of GelMA hydrogel containing final mass concentration of 0 (no nano silver), 25, 50, and 100 mg/L nano silver against Staphylococcus aureus and Escherichia coli were detected. Fibroblasts (Fbs) and adipose stem cells (ASCs) were isolated respectively by enzymatic digestion using the discarded prepuce after circumcision from a 5-year-old healthy boy who was treated in the Department of Urology of the Second Affiliated Hospital of Zhejiang University School of Medicine in July 2020, and the discarded fat tissue after liposuction from a 23-year-old healthy woman who was treated in the Department of Plastic Surgery of the Hospital in July 2020. The Fbs were divided into blank control group (culture medium only), 2 mg/L nano sliver group, 5 mg/L nano sliver group, 10 mg/L nano sliver group, 25 mg/L nano sliver group, and 50 mg/L nano sliver group, which were added with the corresponding final mass concentrations of nano sliver solution, respectively. At 48 h of culture, the Fb proliferation viability was detected by cell counting kit 8 method. The Fbs were divided into 0 mg/L silver-containing GelMA hydrogel group, 10 mg/L silver-containing GelMA hydrogel group, 50 mg/L silver-containing GelMA hydrogel group, and 100 mg/L silver-containing GelMA hydrogel group and then were correspondingly treated. On culture day 1, 3, and 7, the Fb proliferation viability was detected as before. The ASCs were mixed into GelMA hydrogel and divided into 3D bioprinting group and non-printing group. On culture day 1, 3, and 7, the ASC proliferation viability was detected as before and cell growth was observed by live/dead cell fluorescence staining. The sample numbers in the above experiments were all 3. Four full-thickness skin defect wounds were produced on the back of 18 male Sprague-Dawley rats aged 4 to 6 weeks. The wounds were divided into hydrogel alone group, hydrogel/nano sliver group, hydrogel scaffold/nano sliver group, and hydrogel scaffold/nano sliver/ASC group, and transplanted with the corresponding scaffolds, respectively. On post injury day (PID) 4, 7, 14, and 21, the wound healing was observed and the wound healing rate was calculated (n=6). On PID 7 and 14, histopathological changes of wounds were observed by hematoxylin eosin staining (n=6). On PID 21, collagen deposition of wounds was observed by Masson staining (n=3). Data were statistically analyzed with one-way analysis of variance, analysis of variance for repeated measurement, Bonferroni correction, and independent sample t test. Results: The sliver nano particles in nano silver solution with different mass concentrations were all round, in scattered distribution and uniform in size. The silver-containing GelMA hydrogels with different final mass fractions of GelMA all showed pore structures of different sizes and interconnections. The pore size of silver-containing GelMA hydrogel with 10% final mass fraction was significantly larger than that of silver-containing GelMA hydrogels with 15% and 20% final mass fractions (with P values both below 0.05). On treatment day 1, 3, and 7, the concentration of nano silver released from silver-containing GelMA hydrogel in vitro showed a relatively flat trend. On treatment day 14, the concentration of released nano silver in vitro increased rapidly. At 24 h of culture, the diameters of inhibition zone of GelMA hydrogel containing 0, 25, 50, and 100 mg/L nano silver against Staphylococcus aureus and Escherichia coli were 0, 0, 0.7, and 2.1 mm and 0, 1.4, 3.2, and 3.3 mm, respectively. At 48 h of culture, the proliferation activity of Fbs in 2 mg/L nano silver group and 5 mg/L nano silver group was both significantly higher than that in blank control group (P<0.05), and the proliferation activity of Fbs in 10 mg/L nano silver group, 25 mg/L nano silver group, and 50 mg/L nano silver group was all significantly lower than that in blank control group (P<0.05). Compared with the that of Fbs in 0 mg/L silver-containing GelMA hydrogel group, the proliferation activity of Fbs in 50 mg/L silver-containing GelMA hydrogel group and 100 mg/L silver-containing GelMA hydrogel group was all significantly decreased on culture day 1 (P<0.05); the proliferation activity of Fbs in 50 mg/L silver-containing GelMA hydrogel group was significantly increased (P<0.05), while the proliferation activity of Fbs in 100 mg/L silver-containing GelMA hydrogel group was significantly decreased on culture day 3 (P<0.05); the proliferation activity of Fbs in 100 mg/L silver-containing GelMA hydrogel group was significantly decreased on culture day 7 (P<0.05). The proliferation activity of ASCs in 3D bioprinting group show no statistically significant differences to that in non-printing group on culture day 1 (P>0.05). The proliferation activity of ASCs in 3D bioprinting group was significantly higher than that in non-printing group on culture day 3 and 7 (with t values of 21.50 and 12.95, respectively, P<0.05). On culture day 1, the number of dead ASCs in 3D bioprinting group was slightly more than that in non-printing group. On culture day 3 and 5, the majority of ASCs in 3D bioprinting group and non-printing group were living cells. On PID 4, the wounds of rats in hydrogel alone group and hydrogel/nano sliver group had more exudation, and the wounds of rats in hydrogel scaffold/nano sliver group and hydrogel scaffold/nano sliver/ASC group were dry without obvious signs of infection. On PID 7, there was still a small amount of exudation on the wounds of rats in hydrogel alone group and hydrogel/nano sliver group, while the wounds of rats in hydrogel scaffold/nano sliver group and hydrogel scaffold/nano sliver/ASC group were dry and scabbed. On PID 14, the hydrogels on the wound surface of rats in the four groups all fell off. On PID 21, a small area of wounds remained unhealed in hydrogel alone group. On PID 4 and 7, the wound healing rates of rats in hydrogel scaffold/nano sliver/ASC group were significantly higher than those of the other three groups (P<0.05). On PID 14, the wound healing rate of rats in hydrogel scaffold/nano sliver/ASC group was significantly higher than the wound healing rates in hydrogel alone group and hydrogel/nano sliver group (all P<0.05). On PID 21, the wound healing rate of rats in hydrogel alone group was significantly lower than that in hydrogel scaffold/nano sliver/ASC group (P<0.05). On PID 7, the hydrogels on the wound surface of rats in the four groups remained in place; on PID 14, the hydrogel in hydrogel alone group was separated from the wounds of rats, while some hydrogels still existed in the new tissue of the wounds of rats in the other three groups. On PID 21, the collagen arrangement in the wounds of rats in hydrogel alone group was out of order, while the collagen arrangement in the wounds of rats in hydrogel/nano sliver group, and hydrogel scaffold/nano sliver/ASC group was relatively orderly. Conclusions: Silver-containing GelMA hydrogel has good biocompatibility and antibacterial properties. Its three-dimensional bioprinted double-layer structure can better integrate with new formed tissue in the full-thickness skin defect wounds in rats and promote wound healing.

[Effect of sedation on resting energy expenditure in patients with extremely severe burns and the choice of energy estimation formula]

Objective: To investigate the effect of sedation on resting energy expenditure (REE) in patients with extremely severe burns and the choice of REE estimation formula during the treatment. Methods: A retrospective non-randomized controlled clinical study was conducted. From April 2020 to April 2022, 21 patients with extremely severe burns who met the inclusion criteria and underwent mechanical ventilation treatment were admitted to the Department of Burn and Wound Repair of Second Affiliated Hospital of Zhejiang University School of Medicine, including 16 males and 5 females, aged 60 (50, 69) years. Early anti-shock therapy, debridement, skin transplantation, nutritional support, and other conventional treatments were applied to all patients. Patients were sedated when they had obvious agitation or a tendency to extubate, which might lead to aggravation of the disease. REE measurement was performed on patients using indirect calorimetry on post-injury day 3, 5, 7, 9, 11, 14 and every 7 days thereafter until the patient died or being successfully weaned from ventilator. Totally 99 times of measurements were carried out, of which 58 times were measured in the sedated state of patients, and 41 times were measured in the non-sedated state of patients. The age, weight, body surface area, residual wound area, post-injury days of patients were recorded on the day when REE was measured (hereinafter briefly referred to as the measurement day). The REE on the measurement day was calculated with intensive care unit conventional REE estimation formula Thumb formula and special REE estimation formulas for burns including the Third Military Medical University formula, the Peng Xi team's linear formula, Hangang formula. The differences between the sedated state and the non-sedated state in the clinical materials, measured and formula calculated values of REE of patients on the measurement day were compared by Mann-Whitney U test and independent sample t test. The differences between the REE formula calculated values and the REE measured value (reflecting the overall consistency) in the sedated state were compared by Wilcoxon signed rank-sum test. The Bland-Altman method was used to assess the individual consistency between the REE formula calculated value and the REE measured value in the sedated state, and to calculate the proportion of the REE formula calculated value within the range of ±10% of the REE measured value (hereinafter referred to as the accuracy rate). Root mean square error (RMSE) was used to evaluate the accuracy of the REE formula calculated value relative to the REE measured value. Results: Compared with those in the non-sedated state, there was no statistically significant change in patient's age or post-injury days on the measurement day in the sedated state (P>0.05), but the weight was heavier (Z=-3.58, P<0.01), and both the body surface area and the residual wound area were larger (with Z values of -2.99 and -4.52, respectively, P<0.01). Between the sedated state and the non-sedated state, the REE measured values of patients were similar (P>0.05). Compared with those in the non-sedated state, the REE values of patients calculated by Thumb formula, the Third Military Medical University formula, the Peng Xi team's linear formula, and Hangang formula on the measurement day in the sedated state were significantly increased (with Z values of -3.58 and -5.70, t values of -3.58 and -2.74, respectively, P<0.01). In the sedated state, compared with the REE measured value, there were statistically significant changes in REE values of patients calculated by Thumb formula, the Third Military Medical University formula, and Hangang formula on the measurement day (with Z values of -2.13, -5.67, and -3.09, respectively, P<0.05 or P<0.01), while the REE value of patients calculated by the Peng Xi team's linear formula on the measurement day did not change significantly(P>0.05). The analysis of the Bland-Altman method showed that in the sedated state, compared with the REE measured value, the individual consistency of the calculated value of each formula was good; Thumb formula and Hangang formula significantly underestimated the patients' REE value (with the average value of the difference between the formula calculated value and the measured value of -1 463 and -1 717 kJ/d, the 95% confidence interval of -2 491 to -434 and -2 744 to -687 kJ/d, respectively), but the individual differences were small; the Third Military Medical University formula significantly overestimated the patients' REE value (with the average value of the difference between the formula calculated value and the measured value of 3 530 kJ/d, the 95% confidence interval of 2 521 to 4 539 kJ/d), but the individual difference was small; the Peng Xi team's linear formula did not significantly overestimate the patients' REE value (with the average value of the difference between the formula calculated value and the measured value of 294 kJ/d, the 95% confidence interval of -907 to 1 496 kJ/d), while the difference standard deviation was 4 568 kJ/d, which showed a large individual difference. In the sedated state, relative to the REE measured value, the accuracy rates of REE values calculated by Thumb formula, the Third Military Medical University formula, the Peng Xi team's linear formula, and Hangang formula were 25.9% (15/58), 15.5% (9/58), 10.3% (6/58), and 15.5% (9/58), respectively, and RMSE values were 4 143.6, 5 189.1, 4 538.6, and 4 239.8 kJ/d, respectively. Conclusions: Sedative therapy leads to a significant decrease in REE in patients with extremely severe burns undergoing mechanical ventilation treatment. When REE cannot be regularly monitored by indirect calorimetry to determine nutritional support regimens, patients with extremely severe burns undergoing sedation may be prioritized to estimate REE using Thumb formula.

[Effect of Long-term Straw Returning on the Mineralization and Priming Effect of Rice Root-carbon]

Long-term straw returning to the field changes the environmental conditions of rice paddy soil, which affects the mineralization and priming effect of residual rice roots in the soil, but the direction and intensity of its influence is not clear. Therefore, based on a long-term fertilization field experiment, ¹³C-CO₂ isotopic labeling technology and laboratorial incubation were used to analyze the characteristics of mineralization of rice roots and native soil organic carbon, the intensity and direction of the priming effect, and the source partitioning of CO₂ emissions in three treatments, consisting of no fertilization (CK), chemical fertilizer (CF), and straw returning with chemical fertilizer (CFS). The results showed that after 120 days of flooding incubation, the root residue (R) increased the cumulative CO₂ emissions by 617.41-726.27 mg·kg^-1. The cumulative CO₂ emissions from roots and root mineralized proportions in the CFS+R and CF+R treatments were 470.82 and 444.04 mg·kg^-1, respectively, and 18.8% and 17.8%, respectively. These were significantly higher than those in the CK+R treatment (384.19 mg·kg^-1, 15.4%). There was no significant difference in the cumulative CO₂ emissions from native soil organic carbon among the three treatments. However, the mineralized proportion of native soil organic carbon in the CFS+R treatment (4.2%) was significantly lower than that in the CF+R and CK+R treatments (5.4% and 5.8%). The priming effect in the CFS+R treatment was 29.6%, which was significantly lower than that in the CK+R treatment (42.5%) and higher than that in the CF+R treatment (14.4%). A total of 23.47% to 27.59% of the cumulative CO₂ emission of the flooded paddy soil was from the roots, and the remainder was from the soil. In addition, the proportion of CO₂ emission caused by the priming effect was smaller in the CFS+R treatment than that in the CK+R treatment and larger than that in the CF+R treatment. In summary, the long-term straw returning in the flooded paddy soil will increase the mineralization potential of rice roots, but it is more conducive to the stability of the native soil organic carbon.

[Preliminary clinical experience of the novel transcatheter aortic valve system Prizvalve® for the treatment of severe aortic stenosis]

Objective: To evaluate the safety and efficacy of transcatheter aortic valve implantation (TAVI) with the novel Prizvalve^® system in treating severe aortic stenosis. Methods: This is a single-center, prospective, single-arm, observational study. A total of 11 patients with severe aortic stenosis with high risk or inappropriate for conventional surgical aortic valve replacement (SAVR) were included, and TAVI was achieved with the Prizvalve^® system between March 2021 and May 2021 in West China Hospital. Transthoracic echocardiography (TTE) was performed immediately after prosthesis implantation to evaluate mean transaortic gradient and maximal transaortic velocity. The device success rate was calculated, which was defined as (1) the device being delivered via the access, deployed, implanted and withdrawn, (2) mean transaortic gradient<20 mmHg (1 mmHg=0.133 kPa) or a maximal transaortic velocity<3 m/s post TAVI, and without severe aortic regurgitation or paravalvular leak post TAVI. TTE was performed at 30 days after the surgery, and all-cause mortality as well as the major cardiovascular adverse events (including acute myocardial infarction, disabling hemorrhagic or ischemic stroke) up to 30 days post TAVI were analyzed. Results: The age of 11 included patients were (78.1±6.3) years, with 8 males. A total of 10 patients were with NYHA functional class Ⅲ or Ⅳ. Devices were delivered via the access, deployed, implanted and withdrawn successfully in all patients. Post-implant mean transaortic gradient was (7.55±4.08) mmHg and maximal transaortic velocity was (1.78±0.44) m/s, and both decreased significantly as compared to baseline levels (both P<0.05). No severe aortic regurgitation or paravalvular leak was observed post TAVI. Device success was achieved in all the 11 patients. No patient died or experienced major cardiovascular adverse events up to 30 days post TAVI. Mean transaortic gradient was (9.45±5.07) mmHg and maximal transaortic velocity was (2.05±0.42) m/s at 30 days post TAVI, which were similar as the values measured immediately post TAVI (both P>0.05). Conclusions: TAVI with the Prizvalve^® system is a feasible and relatively safe procedure for patients with severe aortic stenosis and at high risk or inappropriate for SAVR. Further clinical studies could be launched to obtain more clinical experience with Prizvalve^® system.

[Characteristics of Paddy Soil Organic Carbon Mineralization and Influencing Factors Under Different Water Conditions and Microbial Biomass Levels]

Paddy soil often undergoes frequent dry-wet alternation. The change in water status not only affects the physical and chemical properties of the soil, but also changes the structure and diversity of the soil microbial communities, which in turn determines the rate of soil organic carbon mineralization. However, the effects of different water conditions and soil microbial biomass levels on the process of soil organic carbon mineralization and its mechanisms are still unclear. Therefore, this study took typical subtropical paddy soil as the research object, applied a laboratory incubation experiment with two water treatments of dry-wet and continuous flooding, and reduced the soil microbial biomass through chloroform fumigation, thereby obtaining high and low soil microbial biomass carbon contents, to elucidate the influencing mechanisms of microbial biomass and water conditions on organic carbon mineralization in paddy soil. The results showed that during the first 30 d of incubation, the dry-wet treatment was in a non-flooded stage and its cumulative CO₂ emissions were significantly lower than those of the continuous flooded treatment. After 30 d, the dry-wet treatment entered the flooded stage. The difference in the cumulative CO₂ emissions of the soils with a high microbial biomass carbon content between the dry-wet and continuous flooding treatments gradually decreased, and there was no significant difference on day 78. In the soil with a low microbial biomass carbon content, the cumulative CO₂ emissions of the dry-wet treatment on day 78 was still significantly lower than that of the continuous flooded treatment. The soils with a low microbial biomass carbon content showed a faster CO₂ emission rate at the beginning of the incubation period (first 20 d), which was 1.1-6.1 times greater than that of the high microbial biomass carbon soils owing to their high soil dissolved organic carbon (DOC) content, and the CO₂ emission rate then gradually decreased until it was below that of the soil with a high microbial biomass carbon content. The soil organic carbon mineralization rate became stable later in the incubation period (days 45-78). The stable mineralization rate of the high microbial biomass carbon soil was 20%-30% higher than that of the low microbial biomass carbon soil. The multiple regression analysis results showed that the decrease in the soil DOC content (ΔDOC) and the increase in the Fe²⁺ content (ΔFe²⁺) significantly affected the change in cumulative CO₂ emissions (ΔCO₂) under continuous flooding conditions, but had no effect on ΔCO₂ during the flooding stage of the dry-wet treatment. The correlation analysis showed that the daily CO₂ emission rate of soils with high microbial biomass carbon was significantly positively correlated with glucosidase activity under dry-wet treatment and significantly negatively correlated with acetylglucosaminidase (NAG) and peroxidase activities under continuous flooding treatment. In the low microbial biomass carbon soils, the daily CO₂ emission rate of the continuous flooding treatment was negatively correlated with the NAG activity, but showed no correlation with enzyme activities under dry-wet management. In summary, the cumulative CO₂ emissions of dry-wet treatment were lower than those of continuous flooding treatment, and the difference was significant in soils with low microbial biomass carbon. The size of the soil microbial biomass determined the level of the stable soil organic carbon mineralization rate. The amount of soluble organic carbon and iron reduction affected the soil CO₂ emissions under continuous flooding conditions, and the soil water conditions affected the daily CO₂ emission rate and its key influencing enzymes. This study provides data and theoretical support for the carbon cycle and carbon sequestration potential in paddy soil.

[Effect of Water Management on Rice Growth and Rhizosphere Priming Effect in Paddy Soils]

The rhizosphere priming effect (RPE) caused by carbon inputs from crop rhizodeposits plays a key role in regulating the carbon emission flux and carbon balance of farmland soils. Due to frequent alternations between dry and wet conditions, CO₂ and CH₄ emissions and the RPE in paddy field ecosystems are significantly different to those of other ecosystems. Therefore, it is of great significance to determine the direction and intensity of the rice RPE under alternations of dry and wet to limit greenhouse gas emissions. In this study, using a ¹³C-CO₂ continuous labeling method combined with a pot-based experiment, the response of rice growth and the RPE under alternating dry and wet and continuous flooding conditions was examined. The results showed that, compared with the continuous flooding treatment, the alternating dry and wet treatments significantly increased aboveground and root biomass and the root-to-root ratio, and also increased soil microbial biomass. Under continuous flooding conditions, fluxes of ¹³CO₂ and ¹³CH₄ increased with rice growth from 10.2 μg·(kg·h)^-1 and 2.8 μg·(kg·h)^-1 (63 d) to 16.0 μg·(kg·h)^-1 and 3.2 μg·(kg·h)^-1 (75 d), respectively. During the 12-day drying process, the emissions of ¹³CO₂ and ¹³CH₄ derived from rhizosphere deposited C decreased by 57.5% and 88.1%. Under continuous flooding conditions, the RPE for CO₂ and CH₄ were positive and increased with the growth of rice. Under the alternating dry and wet treatment, after 12 days of drying, the RPE for CO₂ and CH₄ was reduced from 0.29 mg·(kg·h)^-1 and 12.3 μg·(kg·h)^-1 (63 d) to -0.39 mg·(kg·h)^-1 and 0.07 μg·(kg·h)^-1 (75 d). Thus, alternating wet and dry treatment can effectively promote rice growth and reduce the cumulative emissions of CH₄. Therefore, adopting appropriate field water management is of great significance for increasing rice yields and mitigating greenhouse gas emissions.

Metagenomic and 14 C tracing evidence for autotrophic microbial CO2 fixation in paddy soils

Autotrophic carbon dioxide (CO₂ ) fixation by microbes is ubiquitous in the environment and potentially contributes to the soil organic carbon (SOC) pool. However, the multiple autotrophic pathways of microbial carbon assimilation and fixation in paddy soils remain poorly characterized. In this study, we combine metagenomic analysis with ¹⁴ C-labelling to investigate all known autotrophic pathways and CO₂ assimilation mechanisms in five typical paddy soils from southern China. Marker genes of six autotrophic pathways are detected in all soil samples, which are dominated by the cbbL genes (67%-82%) coding the ribulose-bisphosphate carboxylase large chain in the Calvin cycle. These marker genes are associated with a broad range of phototrophic and chemotrophic genera. Significant amounts of ¹⁴ C-CO₂ are assimilated into SOC (74.3-175.8 mg ¹⁴ C kg^-1 ) and microbial biomass (5.2-24.1 mg ¹⁴ C kg^-1 ) after 45 days incubation, where more than 70% of ¹⁴ C-SOC was concentrated in the relatively stable humin fractions. These results show that paddy soil microbes contain the genetic potential for autotrophic carbon fixation spreading over broad taxonomic ranges, and can incorporate atmospheric carbon into organic components, which ultimately contribute to the stable SOC pool.

[Response of Extracellular Enzyme Activities to Substrate Availability in Paddy Soil with Long-term Fertilizer Management]

The availability of carbon (C), nitrogen (N), and other substrates in soil determines the growth and metabolism of microorganisms and affects the activity of extracellular enzymes. To study the activities of β-1,4-glucosidase (BG) and β-1,4-N-acetylglucosaminidase (NAG) in response to C and N availability, samples that underwent four treatments-non-fertilization (CK), chemical fertilizer (NPK), combination of organic manure and chemical fertilizer (OM), and mixture of straw and chemical fertilizer (ST)-were collected from long-term fertilization paddy soil and incubated for 0, 4, 8, and 12 months to obtain soil with different C and N availability gradients. The results showed that the dissolved organic carbon(DOC) content of OM and ST treatment samples was 2-3 times higher than that of CK and NPK treatment samples. With the increase of DOC and ammonium (NH₄⁺-N) contents, the activities of BG and NAG and the contents of microbial biomass C (MBC) and N (MBN) showed no increase during incubation within each treatment. Fertilization treatments, incubation time, and their interaction are crucial factors varying the contents of DOC, NH₄⁺-N, MBC, and MBN among different fertilization treatments (P<0.01). There was a positive correlation between MBC/MBN and DOC/NH₄⁺-N of OM treatment (P<0.05) and a negative relationship between ln(BG)/ln(NAG) and DOC/NH₄⁺-N of ST treatment (P<0.01), indicating that the availability of substrates played a key role in the potential activity of extracellular enzymes in paddy soil, and the carbon-nitrogen ratio of microbial biomass was controlled by the C/N stoichiometry of substrates in soil. The results have a certain guiding significance for further study on the variation of extracellular enzyme activity in paddy soil, regulating the balance of carbon and nitrogen, and improving the fertility of paddy soil.

[The healthy living master plan (HLMP): Singapore's experience and enlightenment]

The unbalanced economic development, the lifestyle changes of the residents, the aging before getting rich and the burden of non-communicable chronic diseases in China have brought great pressure on China's health system. However, the prevention and control mechanism of chronic diseases in China is far from mature, which restricts the development of the prevention and control of chronic diseases in China. Singapore's new concept on chronic disease management and the the 3-level theoretical framework are good experience in the world and deserve to be learned by China. This article introduced the Healthy Living Master Plan in health promotion practice in Singapore, and made suggestions on construction of health management system to cope with the disease burden in China.

[One case of severe subcutaneous soft tissue infection caused by nonstandard insulin injection]

On January 1st 2018, a male 44 years old diabetic patient with subcutaneous soft tissue infection in right thigh was admitted to our hospital. The patient repeatedly used the same needle to inject insulin subcutaneously in the unsterilized right thigh, and his blood glucose was badly controlled in the long term. Severe subcutaneous soft tissue infection of the right thigh occurred after his fatigue, accompanied with ketoacidosis. Then he received conservative treatment in the local hospital for one month, but the infection persisted. After being transferred to our hospital, we highly suspected the diagnosis of necrotizing fasciitis according to previous test indicators and local B-ultrasound results, but suggestion of aggressive surgery was refused. So we treated him with conservative therapies using sensitive antibiotics and supportive remedies. The patient was basically healed after treatment of 1 month and he was recovered well during the follow-up 2 months after discharged from our hospital. This case emphasizes the importance of standard injection of insulin and early diagnosis of severe subcutaneous soft tissue infection.

[Allocation and Stabilization Responses of Rice Photosynthetic Carbon in the Plant-Soil System to Phosphorus Application]

This research studied the response of the input and allocation of photosynthetic carbon (C) to phosphorus (P) in paddy soils. Two treatments were conducted in this experiment:no P application (P₀) and the application of 80 mg·kg^-1 of P (P₈₀). The rice cultivar was the indica Zhongzao 39. The ¹³C-CO₂ continuous labeling technique was used to identify the photosynthetic C distribution of the rice. The results showed that the application of P₈₀ significantly increased the photosynthates allocation in the rice aboveground, but reduced their allocation in the rhizosphere soil (P<0.05). At the jointing stage, P₈₀ application increased the photosynthetic C content of the rice by 70%, but the root dry weight decreased 31%. Compared with P₀, the total C content of the aboveground rice was increased 0.31 g·pot^-1 by P₈₀. The ratio of rice roots to shoots decreased with the P₈₀ treatment. Moreover, P₈₀ application led to an increase in the photosynthetic microbial biomass in the non-rhizosphere soil C (¹³C-MBC) of 0.03 mg·kg^-1, but still decreased its allocation in the rhizosphere soil. The allocation of photosynthetic C to the particulate organic matter fraction (POC) and mineral fraction (MOC) in the non-rhizosphere soil showed no significant differences between P₀ and P₈₀. Additionally, the P₈₀ fertilization treatment significantly lowered the content of POC in the rhizosphere soil. In summary, P application increased the allocation of photosynthetic C in the soil-rice system, but reduced the accumulation of photosynthetic C in the soil. This research provided a theoretical basis and data supporting the rational application of P fertilizer, and was also of great significance as a study of the transportation and allocation of photosynthetic C and its sequestration potential response to the application of P to the rice soil.

[Characterization of Soil Organic Carbon Mineralization Under Different Gradient Carbon Loading in Paddy Soil]

Available carbon is the most active part of the soil carbon pool. It is also the main carbon source of soil microbes and plays an important role in the processes of soil organic carbon mineralization and accumulation. However, the mechanisms are still not clear how soil organic carbon mineralization and its priming effect (PE) are affected by different input levels of readily available carbon, based on the growth requirements of microbes in paddy soil. In this study, an incubation experiment was conducted by adding different levels (0.5, 1, 3, and 5 times of MBC) of exogenous source organic carbon (¹³C-glucose) to the soil. The mineralization dynamics of labile organic carbon and its priming effect was investigated. The mineralization rate of glucose-C increased significantly with the increasing carbon loading level. The distribution of glucose-C into rapid and slow C pools was also exponentially correlated with the carbon loading (R²=0.99, P<0.05 and R²=0.99, P<0.05, respectively). Negative PE was observed at high carbon loading (3×MBC and 5×MBC); while positive PE was induced by low carbon loading (0.5×MBC and 1×MBC). The cumulative PE was 160.0 mg·kg^-1 and 325.1 mg·kg^-1, respectively, at the end of the incubation. Redundancy analysis showed that the main factors affecting the cumulative PE were MBC, MBN, and DOC at the initial glucose mineralization stage, while β-glucosidase, chitinase, and ammonium nitrogen were the main factors at later stages. Therefore, the readily available carbon loading has an important effect on the organic carbon mineralization and PE in paddy soil. Higher carbon loading was good for the accumulation of organic carbon sequestration in paddy soil. This study is of great scientific significance for revealing the activity of organic carbon in paddy fields and for its contribution to the development of sustainable agriculture.

[Transformation and Distribution of Soil Organic Carbon and the Microbial Characteristics in Response to Different Exogenous Carbon Input Levels in Paddy Soil]

The turnover of soil organic carbon (SOC) and the activity of soil microbes can be influenced by exogenous carbon. However, microbial response characteristics of the transformation and distribution of available organic carbon under different levels remain unclear in paddy soils. ¹³C-labeled glucose was used as a typical available exogenous carbon to simulate indoor culture experiments added at different levels of soil microbial biomass carbon (MBC) (0×MBC, 0.5×MBC, 1×MBC, 3×MBC, and 5×MBC) to reveal the process of C-transformation and distribution. The characteristics of microbial response in the process of exogenous carbon turnover was also monitored. The 96-well microplate fluorescence analysis was adopted to determine the activities of cellobiose hydrolase (CBH) and β-glucosidase (β-Glu). The results showed that, in 2 d of incubation, the ratio of labeled glucose carbon to dissolved organic carbon (¹³C-DOC/DOC) or to SOC (¹³C-SOC/SOC) was positively correlated with the amount of glucose added. The incorporation of glucose C (¹³C) into MBC reached the highest value (18.96 mg·kg^-1) at 3×MBC treatment but decreased thereafter. The ¹³C allocation rate was mainly positively correlated with MBC, Olsen-P, and DOC. At 60 d, ¹³C-DOC, ¹³C-MBC, and ¹³C-SOC decreased significantly to less than 0.02 mg·kg^-1, 2 mg·kg^-1, and 10 mg·kg^-1 in soil, and it was positively correlated with the amount of glucose added. Compared with CK, CBH enzyme activity increased significantly after the addition of glucose, and for the 3×MBC treatment it was increased by 22.6 times, which was significantly higher than those of other treatments (P<0.05). However, β-Glu enzyme activity increased only in the 3×MBC and 5×MBC treatments, wherein it decreased with increasing amounts of added glucose. NH₄⁺-N, pH, β-Glu, and CBH were the primary factors affecting the distribution rate of ¹³C. In conclusion, the conversion of exogenous carbon to SOC increased with increased amounts of added organic carbon. This changed the activity of soil enzymes; however, microbial utilization of exogenous carbon may have a saturation threshold. Within the saturation threshold, the conversion rate of organic matter was directly proportional to the amount of added organic matter. When the saturation threshold was exceeded, the conversion rate of organic matter decreased. Therefore, the appropriate addition of exogenous carbon is beneficial, as it can increase SOC in rice fields and improve the quality of the crop growth environment.

[Effect of Phosphorus Addition on the Abundance of Autotrophic CO2-Fixation Microorganisms in Rhizospheric Soil from a Phosphorus-Limited Paddy Field]

A rice pot experiment was conducted to investigate the effect of phosphorus addition on the abundance of autotrophic CO₂-fixation microorganisms using phosphorus-limited paddy soil from the Changsha Observation and Research Station for the Agricultural Environment. Rice seedlings were transplanted in the paddy soil with or without phosphorus addition, corresponding to P-treated-pot (P) or control pot (CK), respectively. Rhizosphere soils were collected from the P and CK treatments during the tillering and shooting stages. The physical and chemical soil properties were measured and the abundance of autotrophic CO₂-fixation microorganisms was quantified with a real-time PCR technique based on four functional genes (cbbL, cbbM, accA, and aclB) involved in three CO₂-fixation pathways (CBB cycle, rTCA cycle, and 3-hydroxypropionate/4-hydroxybutyrate cycle). The results show that phosphorus addition improves the concentrations of DOC and Olsen-P and the pH value, whereas negative effects on the MBC and NH₄⁺-N concentrations are revealed during the tillering stage. The effect of phosphorus addition on the NO₃^--N concentration in the tillering and shooting stages differs. Phosphorus addition significantly increases the abundances of the cbbL, cbbM, accA, and aclB genes, which are 156%, 99%, 110%, and 193% higher than those of the CK treatment in the tillering stage. However, this positive effect is not notable for the cbbL, accA, and aclB genes during the shooting stage. Redundancy analysis (RDA) shows that Olsen-P is the environmental factor that most significantly affects the abundance of autotrophic CO₂-fixation microorganisms.

[Effects of Varying Long-term Fertilization on Organic Carbon Mineralization and Priming Effect of Paddy Soil]

A laboratory incubation experiment was conducted using the ¹⁴C isotope labeling technique to study the characteristics of organic carbon mineralization and their response to glucose addition when treated with a combination of straw and chemical fertilizer (ST), inorganic fertilizer (NPK), and non-fertilization (CK). The cumulative mineralization rate (ratio of accumulated mineralization amount to total organic carbon content) in CK reaches 1.64% at the end of incubation (56 days). The cumulative mineralization rate during NPK and ST treatments is significantly lower than that in CK (by 0.34% and 0.39%, respectively). This indicates that long-term fertilization affects the soil carbon sequestration. Varying long-term fertilization influences the response of paddy soil to glucose addition and leads to different levels of the priming effect. The priming effect on soil organic carbon mineralization of the three treatments gradually changes from negative to positive with increasing incubation time. The significantly negative cumulative priming effect in ST and NPK after 56 d is 22.07 and 9.05 times higher than that in CK, respectively. The results of the structural equation model indicate that the NH₄⁺-N and DOC contents indirectly influence the cumulative priming effect on soil organic carbon by affecting the MBC and MBN contents. The NH₄⁺-N concentration has a direct and significant negative effect on the cumulative priming effect. In conclusion, long-term fertilization treatments reduce the cumulative organic carbon mineralization rate of paddy soil. Fertilizer, especially the combination of straw and chemical fertilizer, enhances the soil carbon sequestration and accumulation.

[Effect of CO2 Doubling and Different Plant Growth Stages on Rice Carbon, Nitrogen, and Phosphorus and Their Stoichiometric Ratios]

The variation characteristics of ecological stoichiometric ratios can reflect the nature of plant adaptation to environmental changes. The C, N, and P contetns, and their stoichiometric ratios in different organs of rice were studied using a CO₂ continuous labeling system, by simulating the increase of atmospheric CO₂ concentration (800×10^-6). The results showed that CO₂ doubling promoted the growth of rice organs and increased the root/shoot ratio. CO₂ doubling reduced the shoot TN content in different growth periods, increased the C/N ratio in the rice root, shoot, and grain, decreased the N use efficiency, and improved the P use efficiency. Multiple comparison and Venn diagram analyses showed that CO₂ concentration only has a significant impact on the TN content in the rice shoot; it contributed little to the variation in rice nutrient content and their stoichiometric ratios, indicating that CO₂ doubling had no effect on these. Under the condition of elevated atmospheric CO₂ concentrations, the C, N, and P contents and their stoichiometirc ratios, in rice organs had good homeostasis, and the stoichiometric change during growth periods was consistent with "the Growth Rate Theory". In farmland management, appropriate nitrogen fertilizers can alleviate the nutrient balance pressure caused by the increase in CO₂ concentration.

[Effects of Long-term Fertilization on Enzyme Activities in Profile of Paddy Soil Profiles]

The enzyme activity, which is closely related to soil material cycling (mineralization, transformation, etc.), can reflect soil quality and nutrient status. In order to explore the effect of long-term fertilization on the enzyme activity in paddy soil profile (0-40 cm), soils with organic fertilizer and inorganic fertilizer, and non-fertilized soils were selected, and the carbon and nitrogen contents, and the activities of β-1,4-glucosidase (BG), and β-1,4-N-acetylglucosaminidase (NAG) in 10cm depths of soil were analyzed. The results showed that the activities of BG and NAG in the soils treated with inorganic fertilizer and organic fertilizer increased by 0.73-47.87 nmol·(g·h)^-1 and 1.33-128.81 nmol·(g·h)^-1, and 0.19-9.72 nmol·(g·h)^-1 and 0.92-57.66 nmol·(g·h)^-1, respectively, compared to those for non-fertilized soil. Soil enzyme activity decreased with increasing soil depth. Soil enzyme activity in soil from 0-20 cm was significantly higher than that of soil from 20-40 cm. Soil enzyme activities were significantly affected by long term fertilization at different soil depths. RDA analysis showed that soil carbon and nitrogen contents had significant positive relationships with the activities of BG and NAG in the 0-20 cm soil profiles, however, negative relationships were observed in the 20-40 cm soil profiles. The long-term application of organic fertilizer significantly increased soil biomass and enzyme activity, both of which decreased with the increase in soil depth. Long-term fertilization could increase soil nutrient contents, microbial biomass, and extracellular enzyme activities, which has important theoretical significance for optimizing farmland fertilizer management and improving soil productivity.

[Dynamics of Rice Photosynthesized Carbon Input and Its Response to Nitrogen Fertilization at the Jointing Stage:13 C-CO2 Pulse-labeling]

Photosynthesized carbon (C) is an important source of soil organic C in paddy fields, and its input and distribution are affected by rice growth and soil fertility. Fertilizer application plays an important role in rice growth. The ¹³C pulse-labeling method was used to quantify the dynamics and distribution of input photosynthesized C in the rice-(rhizosphere-and bulk-) soil system and its response to nitrogen fertilizer (N) application. The results suggested that N fertilization significantly increased the rice aboveground and the root biomass and decreased the rice biomass root/shoot ratio. The amount of assimilated ¹³C gradually decreased in the rice plants but gradually decreased over 0-6 days and increased over 6-26 days in the rhizosphere and bulk soil during rice growth. N fertilization significantly increased the amount of assimilated ¹³C in the rhizosphere soil by 9.5%-32.6% compared with the control. In comparison to the unfertilized treatment, the application of N fertilization resulted in higher photosynthetic¹³C in rice aboveground and in the root by 24.5%-134.7% and 9.1%-106%, respectively. With the N fertilized and unfertilized treatments, 85.5%-93.2% and 91.3%-95.7%, respectively, of input photosynthetic ¹³C was distributed in the rice plants. The results suggested that N fertilization significantly affected the distribution of photosynthesized C in the rice-soil system (P<0.01). After 26 days of pulse labeling, the distribution of photosynthetic ¹³C into rice aboveground was increased by 13.4%, while the distribution into the rhizosphere and bulk soil were decreased by 21.9% and 52.2%, respectively, in the N fertilized treatments compared with the unfertilized treatments. Therefore, the N application increased the distribution of photosynthesized carbon in the soil-rice system but decreased the accumulation in the rhizosphere and bulk soil. The findings of this study provided a theoretical basis for our understanding of the dynamic of photosynthetic C in the plant-soil system and the assimilation of the soil organic matter pool in the paddy soil ecosystem.

Fe(II)/Cu(II) interaction on goethite stimulated by an iron-reducing bacteria Aeromonas Hydrophila HS01 under anaerobic conditions

Copper is a trace element essential for living creatures, but copper content in soil should be controlled, as it is toxic. The physical-chemical-biological features of Cu in soil have a significant correlation with the Fe(II)/Cu(II) interaction in soil. Of significant interest to the current study is the effect of Fe(II)/Cu(II) interaction conducted on goethite under anaerobic conditions stimulated by HS01 (a dissimilatory iron reduction (DIR) microbial). The following four treatments were designed: HS01 with α-FeOOH and Cu(II) (T1), HS01 with α-FeOOH (T2), HS01 with Cu(II) (T3), and α-FeOOH with Cu(II) (T4). HS01 presents a negligible impact on copper species transformation (T3), whereas the presence of α-FeOOH significantly enhanced copper aging contributing to the DIR effect (T1). Moreover, the violent reaction between adsorbed Fe(II) and Cu(II) leads to the decreased concentration of the active Fe(II) species (T1), further inhibiting reactions between Fe(II) and iron (hydr)oxides and decelerating the phase transformation of iron (hydr)oxides (T1). From this study, the effects of the Fe(II)/Cu(II) interaction on goethite under anaerobic conditions by HS01 are presented in three aspects: (1) the accelerating effect of copper aging, (2) the reductive transformation of copper, and (3) the inhibition effect of the phase transformation of iron (hydr)oxides.

[Responses of Extracellular Enzymes to Nitrogen Application in Rice of Various Ages with Rhizosphere and Bulk Soil]

Ecological enzyme activities are closely relevant to the carbon and nitrogen decomposition and mineralization of paddy soils, which can reflect the growth and metabolism of microorganisms. In order to clarify the response to nitrogen application by different enzymes in the rhizosphere and bulk soil of rice, the rhizosphere and bulk soil were identified using a rhizosphere bag. In addition, the β-1,4-glucosidase (BG) enzyme; β-1,4-N-acetylglucosaminidase (NAG) enzyme; and the effects of the rhizosphere, nitrogen application, and growth period on soil enzyme activities were analyzed. The results showed that the activity of the BG enzyme decreased by 7.4-13.5 nmol·(g·h)^-1 in the jointing stage and increased by 7.0-31.4 nmol·(g·h)^-1 in the maturity stage, and the activity of the BG enzyme in the rhizosphere and bulk soil also changed with the growth period of rice.compared with no nitrogen fertilizer, nitrogen application increased NAG enzyme activity by 1.1 times and rhizosphere soil by 0.3 times in the bulk soil in the maturity stage. Nitrogen application and growth period had significant effects on soil BG enzyme activity, whereas the interaction within rice growth stage, nitrogen application, and rhizosphere effect had significant effects on NAG enzyme activity. The result of RDA showed that the soil microbial biomass carbon (MBC) and dissolved organic carbon (DOC) contents mainly affected the activity of extracellular enzymes in the rice rhizosphere soil, whereas the activities of enzymes in the rhizosphere soil were mainly affected by microbial biomass nitrogen (MBN) and NH₄⁺-N. The relationships between soil enzyme activity and various factors are complex, and the effects of nitrogen addition on microbial community composition needs to be considered after accounting for plant physiological characteristics, soil enzyme activity, and soil characteristics.

[Effect of Straw Application on the Dynamics of Exogenous Nitrogen and Microbial Activity in Paddy Soil]

Returning straw to the field provides an important source of fertilizer that can increase soil fertility. However, the rate of straw carbon utilization is low and large amounts of greenhouse gases are emitted due to the high carbon to nitrogen ratio of the straw mass. In this regard, the application of inorganic nitrogen and phosphate fertilizers can control the ratio of elements in the soil, increase the activity of microorganisms and their utilization of elements, and promote the improvement of soil fertility. In this study, straw application conditions were simulated, and inorganic nitrogen fertilizer labeled with ¹⁵N was added to examine the effects of different nutrient fertilizer additions on the transformation and distribution of exogenous nitrogen in the soil, and also the characteristics of the microbial response. The results showed that application of straw increased the contents of ammonia nitrogen and total nitrogen in the soil and soil solution. When both straw and inorganic nitrogen fertilizer were applied, the ¹⁵N-TN in the soil remained at 28 to 33 μg during the 100-day culture phase. In contrast, ¹⁵N-NH₄⁺ increased gradually during the initial 30 days of the culture phase, but subsequently decreased gradually. Application of phosphate increased the contents of ¹⁵N-TN and ¹⁵N-NH₄⁺ in the soil, but decreased the content of ¹⁵N in the soil solution by 28%. The distribution of inorganic nitrogen in the soil showed that the proportion of ¹⁵N in the soil remained at 52%-61%. Addition of phosphate fertilizer increased the distribution ratio of ¹⁵N in the soil by up to 16.5%, whereas the proportion of ¹⁵N in the soil solution decreased from 36% on the fifth day to 30% on the 100^th day, thereby the loss amount of ¹⁵N reduced by 1.2-fold. Addition of straw promoted microbial activity and significantly increased the microbial biomass nitrogen (MBN) content of the soil. Addition of inorganic fertilizer further promoted the microbial activity of the soil. After the 100-day culture experiment, the addition of straw, inorganic nitrogen, and phosphate fertilizer increased MBN to between 2.0-fold and 2.2-fold that of the control treatments. Addition of phosphate fertilizer increased the utilization of ¹⁵N by microorganisms, so that the amount of ¹⁵N-MBN was 1.5-fold higher than that of treatments where only straw and nitrogen fertilizer were added. Examination of soil enzyme activity showed that nitrogen fertilizer reduced soil enzyme activity and substrate affinity. When both nitrogen and phosphate fertilizers were added, the enzyme activity was 48.1% higher than that when only straw was added. The findings of this study thus provide a theoretical basis for furthering our understanding on the nitrogen cycle of the paddy soil ecosystem, the improvement of soil fertility, and the reduction of greenhouse gas emissions.

[Input and Distribution of Photosynthesized Carbon in Soil-Rice System Affected by Water Management and Nitrogen Fertilization]

Fertilizer and water management are two key factors for rice growth. A better understanding of the carbon (C) cycling in paddy soil requires investigation into the input characteristics and distribution dynamics of photosynthesized carbon in rice-soil system. We grew rice (Zhongzao 39) in PVC pots and used the ¹³ C-CO₂ continuous labeling method to quantify the allocation of photosynthesized carbon in rice-soil system under two regimes(Drying-rewetting vs. continuous watering) and N fertilization (250 mg·kg^-1vs. no addition). The results showed that nitrogen fertilizer application increased rice shoot biomass and the amount of C and N, but had no significant influence on rice root biomass. Thus, nitrogen fertilizer application decreased rice biomass root/shoot ratio significantly. Drying-rewetting with N fertilizer treatment resulted in higher total C and N amount by 22% and 33%, respectively, in the shoot, and by 36% and 44%, respectively in the root than continuous watering with nitrogen fertilizer treatment. These results indicated that nitrogen fertilizer application promoted the growth of rice shoot. Nitrogen fertilizer application significantly increased the ¹³ C content in rice shoot by 32%-83% over the control without N addition. Nitrogen fertilizer application also increased the ¹³ C recovery in rice shoot by 6%-32%, but decreased that in the root by 18%-59%. Pertaining to water effect, drying-rewetting with N application increased the amount of ¹³ C in rice shoot and root. However, without N addition, the amount and the recovery of ¹³ C in shoot dropped by 10.3 mg·pot^-1 and 12%, respectively, compared with the continuous watering treatment. The root, on the other hand, recorded increases in both the amount and the recovery of ¹³ C by 1.9 mg·pot^-1 and 57%, respectively. Furthermore, the deposition of assimilated C into rhizosphere-soil increased by both the individual and the interactive effects of N fertilizer application and drying-rewetting treatment. Thus, combining N fertilizer and drying-rewetting water management led to more increased allocation and deposition of photosynthesized carbon in soil-rice system compared with combined continuous flooding and N application. This study was able to quantify the partitioning and allocation of rice photosynthesized carbon into different plant and soil pools under different water and N fertilizer treatments, and can serve as a useful guide for better water and nutrient management practices in paddy-rice production that can achieve both sustainable high yield and sequestration of more C within the paddy soil system.

[Effects of Soil Texture on Autotrophic CO2 Fixation Bacterial Communities and Their CO2 Assimilation Contents]

Autotrophic bacteria can assimilate atmospheric carbon dioxide (CO₂) and convert CO₂ into organic carbon. The CO₂ fixation by autotrophic bacteria is important for the improvement of carbon sequestration in agricultural soils. However, the effect of soil texture on autotrophic CO₂ fixation bacteria and their CO₂ fixation capacity is still unknown. Here, two paddy soils with different textures (loamy clay soil and sand clay loam soil) were incubated with continuous ¹⁴C-CO₂ in a glass chamber. The two soils were developed from the same parent. At the end of 110 days incubation, the ¹⁴C-CO₂ incorporated in soil organic carbon (¹⁴C-SOC), microbial biomass carbon (¹⁴C-MBC) and dissolved organic carbon (¹⁴C-DOC) were measured to explore the effects of soil texture on the autotrophic bacterial CO₂ fixation rates. The effect of soil texture on the composition and diversity of autotrophic CO₂ fixation bacterial community was investigated using cloning and sequencing of the cbbL gene, which encodes ribulose-1,5-biphosphate carboxylase/oxygenase (RubisCO) in the Calvin cycle. The results showed that the average contents of ¹⁴C-SOC, ¹⁴C-MBC and ¹⁴C-DOC were 133.81, 40.16 and 8.10 mg·kg^-1 in loamy clay soil, respectively, which were significantly higher than their corresponding contents in sand clay loam soil (P<0.05). This suggested that soil texture not only affected the amounts of autotrophic bacteria CO₂ fixation but also had an effect on the transformation of microbial assimilated ¹⁴C in soil. The cbbL gene libraries of two soils were significantly different as revealed by libshuff analyses (P<0.05). Phylogenetic analysis showed that cbbL sequences from the loamy clay soil were closely affiliated with known cultures such as Rhodoblastus acidophilus, Blastochloris viridis, Thauera humireducens, Mehylibium sp.and Variovorax sp., whereas these sequences belonging to the sand clay loam soil were related to branching lineages originating from Rhizobiales and Actinomycetales.Rarefaction curve, clone library coverage and diversity index analysis based on bacterial cbbL clone libraries indicated that the loamy clay soil had higher cbbL gene diversity compared to the sand clay loam soil. These results suggested that soil texture had a pronounced effect on the composition and diversity of autotrophic CO₂ fixation bacterial communities. The higher clay content, nutrient availability and cation exchange capacity may stimulate the growth and activity of autotrophic bacteria, and result in the higher amounts of ¹⁴C in loamy clay soil. These data broaden the understanding and knowledge of mechanisms of microbial carbon fixation and their influencing factors in agricultural soils.

Poly[[tetra-aqua-bis[μ(4)-2,2'-(p-phenyl-ene-di-oxy)diacetato][μ(2)-2,2'-(p-phenyl-ene-di-oxy)diacetato]dierbium(III)] hexa-hydrate]

The asymmetric unit of the title compound, [Er(2)(C(10)H(8)O(6))(3)(H(2)O)(4)]·6H(2)O, comprises one Er(3+) ion, one and a half 2,2'-(p-phenyl-enedi-oxy)diacetate (hqda) ligands, two coordinated water mol-ecules and three uncoordinated water mol-ecules. The Er(3+) ion is nine-coordinated by seven O atoms from hqda ligands and two O atoms from water mol-ecules. In the title compound, there are two types of crystallographically independent ligands: one with an inversion center in the middle of the ligand is chelating on both ends of the ligand towards each one Er center; the other hqda ligands are bridging-chelating on one side, and bridging on the other end of the ligand. Two adjacent Er(3+) ions are thus chelated and bridged by -COO groups from hqda ligands in three coordination modes (briding-chelating, bridging and chelating). These building blocks are linked by OOC-CH(2)O-C(6)H(4)-OCH(2)-COO spacers, forming two-dimensional neutral layers. Adjacent layers are linked by O-H⋯O hydrogen-bonding inter-actions, forming a three-dimensional supermolecular network.

catena-Poly[diaqua-tris(μ(3)-biphenyl-2,2-dicarboxyl-ato)disamarium(III)]

The title compound, [Sm(2)(C(14)H(8)O(4))(3)(H(2)O)(2)](n), is composed of one-dimensional chains and is isostructural with previously reported compounds [Wang et al. (2003 ▶). Eur. J. Inorg. Chem. pp. 1355-1360]. The asymmetric unit contains two Sm atoms, each of which lies on a crystallographic twofold axis. Both crystallographically independent Sm atoms are coordinated by eight O atoms in a distorted dodeca-hedral arrangement. The polymeric chains run along [001]. Adjacent chains are connected through π-π inter-actions [centroid-centroid distance = 3.450 (2) Å], forming a two-dimensional supra-molecular network.

Some characteristics of nutrition metabolism and hormone control during the first 24 hours in neonatal calves

Six male Holstein calves of spontaneous delivery and with jugular vein catheter were chosen to study the characteristics of nutrition metabolism and hormone control during the first 24 h of age after birth. The results showed that plasma fructose (Fru) and lactic acid (LA) concentrations were highest at birth, fell significantly during the first 2 h of life, and then dropped further until 24 h. Glucose (Glu) increased at 0.5 h after birth, followed by a gradual decrease until 8 h, with a general upward trend thereafter. Free fatty acid (FFA) was very low at birth, rose rapidly within 2 h of live, and kept a relatively high concentration thereafter. Total protein (TP) had not obvious change and fluctuated at a low level during the first 24 h of age. The rise of insulin (Ins) at 1 h of age was observed, with a downward tendency thereafter. Plasma cortisol (Cort) level was high during 1 h of age and tend to drop thereafter. An obviously rising tendency of T4 and T3 was found during the first 4 h of life, followed by their keeping relatively high levels although decreasing constantly in neonatal calves.

Characteristics and developmental changes of some plasma nutrition metabolites in neonatal lambs

Twelve spontaneously delivered Hu sheep neonatal lambs with a birth weight of 1.5-4.5 kg were used to study the characteristics and developmental changes of plasma nutrition metabolites during postnatal period in 7 days of age. The results showed that plasma glucose (Glu) concentration rose significantly within 4 h after lambing and then maintained a fluctuent upward tendency until day 7 of age. Fructose (Fru) and lactic acid (LA) concentrations were highest at 1 h after birth, tended to drop thereafter, and remained relatively stable levels after day 3 of age. Free fatty acid (FFA) tended to increase within 12 h after birth, followed by keeping comparatively high levels although decreasing fluctuently. An obvious increase of total protein (TP) occurred within 8 h after birth and then remained a relatively high concentration until day 7 of age. a-Amino nitrogen (a-NH2N) tended to rise by 4 h and fell slightly thereafter, urea nitrogen (UN) had an elevated concentration from birth to 8 h and then dropped obviously. Both a-NH2N and UN appeared to be fairly stable during the first week of age in neonatal lambs.

The development changes and correlations of some blood hormone levels and immune indexes during the postnatal period in neonatal calves

The developmental changes and correlations of some hormone levels and immune parameters in six spontaneously delivered Holstein calves with a birth weight of 40-50 kg were studied for a postnatal period of 1-15 days after birth. The mean levels of insulin (I), glucagon (Gc), cortisol (C) and growth hormone (GH) before feeding on day 1 were 9.68 +/- 3.27 muu/ml, 685.39 +/- 95.42 pg/ml, 14.27 +/- 5.58 micrograms/dl and 0.85 +/- 0.10 ng/ml respectively. I and GH increased on day 2 and then decreased to a steady level. Gc and C fell fluctuantly within week 1 and remained at a stable level after then. WBC, neutrophil percentage, B-lymphocyte percentage, albumin percentage decreased with day of age in 1st week and lymphocyte percentage, T-lymphocyte percentage, T-G (total globulin) percentage and gamma-G percentage increased with day of age in 1st week and then reached a steady level. The correlations between some hormone levels and immune parameters indicated that C and Gc have significantly negative correlations with gamma-G (%), T-G (%) and T-lymphocyte (%) respectively. WBC is positively correlated to C and Gc significantly. The correlations of I and GH with some immune parameters have no significance.