Impact of the Kasai Procedure and the Length of Native Liver Survival Time on Outcomes of Liver Transplantation for Biliary Atresia.

The aim is to explore the impact of the Kasai procedure (KP) and the length of native liver survival time (NLST) on outcomes of liver transplantation (LT). Patients with biliary atresia (BA), who underwent LT in Beijing Friendship Hospital from January 2017 to December 2019, were enrolled and divided into non-KP (N-KP) and post-KP (P-KP) groups. The patients in the P-KP group were further divided into early failure (KP-EF) defined by NLST <1 year, medium failure (KP-MF, NLST 1-5 years), and late failure (KP-LF, NLST >5 years) subgroups. Clinical data at baseline and during follow-up were collected. The inverse probability of treatment weighting method was used to evaluate the independent effect of KP and the length of NLST on clinical outcomes. Among 197 patients with BA, the N-KP group accounted for 43 (21.8%), KP-EF 71 (46.1%), KP-MF 59 (38.3%), and KP-LF 24 (15.6%) cases, respectively. The N-KP and KP-EF groups had significantly longer hospitalization and intensive care unit stays after LT. Graft and overall survival rates were 93.0% in the N-KP group and 97.4% in P-KP group, respectively. The mortality rate in the P-KP group were significantly lower compared with that of the N-KP group with a hazard ratio (HR) of 0.2 (P = 0.02). The risks of biliary and vascular complications and cytomegalovirus (CMV) infection after LT were significantly higher in KP-EF group than those in the KP-MF and KP-LF groups (HRs = 0.09, 0.2, and 0.3, respectively; all P < 0.001). The KP significantly improved after LT overall survival. Patients with early native liver failure after KP have significantly higher risks for biliary and vascular complications and CMV infection.

IL-9 contributes to the host immune response against Helicobacter pylori and helps limit infection in a Mouse Model.

BACKGROUND: As an important mediator in lots of diseases, interleukin-9 (IL-9) can be a protector or pro-inflammatory cytokine depending on the complicated inflammatory milieu. Helicobacter pylori (H. pylori) induced a series of immunology cells and cytokines change, and however, the role of IL-9 in H. pylori infection remains unknown. MATERIALS AND METHODS: Wild-type and IL-9 deficient mice were infected with H. pylori by means of intragastric administration. The colonization of H. pylori bacteria was measured by detecting specific 16s rDNA, and the intensity of inflammation was observed by H&E stain. The expression level of inflammation cytokines was determined by ELISA and quantitative real-time PCR. RESULTS: IL-9 was increased due to the attack of H. pylori, besides deletion of Il9 aggravated the bacterial colonization and inflammation intensity. In addition, treatment of rmIL-9 reduced colonized H. pylori and inflammation level, indicated that IL-9 was a protector for the host against this bacterium. Followed by the H. pylori infection, interferon (IFN)-γ and interleukin (IL)-17A were up-regulated as expected, and nevertheless, the expression of IL-17A shared a positive relationship with IL-9 while IFN-γ negative associated with IL-9. Moreover, we also proved that Treg cells were not involved in the protective effect of IL-9, and meanwhile, CD4+ CD25- T cells secreted more IFN-γ and less IL-17A in vitro due to the deletion of Il9. CONCLUSIONS: IL-9 plays a protective role against H. pylori and the protection associated with cytokines change including IFN-γ and IL-17A.

The research of aptamer biosensor technologies for detection of microorganism.

The activities and transmissions of microorganisms are closely related to human, and all kinds of diseases caused by pathogenic microorganisms have attracted attention in the world and brought many challenges to human health and public health. The traditional microbial detection technologies have characteristics of longer detection cycle and complicated processes, therefore, which can no longer meet the detection requirements in the field of public health. At present, it is the focus to develop and design a novel, rapid, and simple microbial detection method in the field of public health. Herein, this article summarized the development of aptamer biosensor technologies for detection of microorganism in the aspect of bacteria, viruses, and toxins in detail, including optical aptamer sensors such as fluorometry and colorimetry, electrochemical aptamer sensors, and other technologies combined with aptamer. KEY POINTS: • Aptamer biosensor is a good platform for microbial detection. • Aptamer biosensors include optical sensors and electrochemical sensors. • Aptamer sensors have been widely used in the detection of bacteria, viruses, and other microorganisms.

Vinylene-Linked Covalent Organic Frameworks (COFs) with Symmetry-Tuned Polarity and Photocatalytic Activity.

The polarity of a semiconducting molecule affects its intrinsic photophysical properties, which can be tuned by varying the molecular geometry. Herein, we developed a D3h -symmetric tricyanomesitylene as a new monomer which could be reticulated into a vinylene-linked covalent organic framework (g-C54 N6 -COF) via Knoevenagel condensation with another D3h -symmetric monomer 2,4,6-tris(4'-formyl-biphenyl-4-yl)-1,3,5-triazine. Replacing tricyanomesitylene with a C2v -symmetric 3,5-dicyano-2,4,6-trimethylpyridine gave a less-symmetric vinylene-linked COF (g-C52 N6 -COF). The octupolar conjugated characters of g-C54 N6 -COF were reflected in its scarce solvatochromic effects either in ground or excited states, and endowed it with more promising semiconducting behavior as compared with g-C52 N6 -COF, such as enhanced light-harvesting and excellent photo-induced charge generation and separation. Along with the matched energy level, g-C54 N6 -COF enabled the two-half reactions of photocatalytic water splitting with an average O2 evolution rate of 51.0 µmol h-1 g-1 and H2 evolution rate of 2518.9 µmol h-1 g-1 . Such values are among the highest of state-of-the-art COF photocatalysts.

A composite prepared from carboxymethyl chitosan and aptamer-modified gold nanoparticles for the colorimetric determination of Salmonella typhimurium.

An aptamer-based assay is described for the determination of Salmonella typhimurium (S. typh). Carboxymethyl chitosan was loaded with amino-modified aptamer against S. typh, and then adsorbed on gold nanoparticles by electrostatic interaction to form a composite that acts as the molecular recognition element. In the presence of S. typh, it will be bound by the aptamer, and this changes the structure of the recognition element. On addition of salt solution, the gold nanoparticles agglomerate so that the color of the solution changes from red to blue. S. typh can be detected via measurement of the absorbance at 550 nm. Absorbance increases linearly with the logarithm of the S. typh concentration in the range from 100 to 109 cfu·mL-1. The limit of detection is 16 cfu·mL-1. The specificity and practicability of the assay were evaluated. The recoveries of S. typh from spiked milk samples are between 92.4 and 97.2%. The analytical results are basically consistent with those of a plate counting method. Graphical abstract Schematic representation of the colorimetric assay for Salmonella typhimuium (S. typh) using carboxymethyl chitosan (CMCS)-aptamer (Apt)-gold nanoparticles (AuNPs) composites.

An Olefin-Linked Covalent Organic Framework as a Flexible Thin-Film Electrode for a High-Performance Micro-Supercapacitor.

Developing effective synthetic strategies as well as enriching functionalities for sp2 -carbon-linked covalent organic frameworks (COFs) still remains a challenge. Now, taking advantage of a variant of Knoevenagel condensation, a new fully conjugated COF (g-C34 N6 -COF) linked by unsubstituted C=C bonds was synthesized. Integrating 3,5-dicyano-2,4,6-trimethylpyridine and 1,3,5-triazine units into the molecular framework leads to the enhanced π-electron communication and electrochemical activity. This COF shows uniform nanofibrous morphology. By assembling it with carbon nanotubes, a flexible thin-film electrode for a micro-supercapacitor (MSC) can be easily obtained. The resultant COF-based MSC shows an areal capacitance of up to 15.2 mF cm-2 , a high energy density of up to 7.3 mWh cm-3 , and remarkable rate capability. These values are among the highest for state-of-the-art MSCs. Moreover, this device exhibits excellent flexibility and integration capability.

[Clinical analysis and autoimmune regulator gene mutation of autoimmune polyendocrinopathy syndrome type I in a family: a report of one case].

The clinical data of one patient with autoimmune polyendocrinopathy syndrome type I were collected. PCR-DNA direct bidirectional sequencing was applied for mutation screening of 14 exons in autoimmune regulator (AIRE) gene in the patient and her parents. A total of 50 unrelated healthy controls were selected and tested. The bioinformatic methods were used to predict the possible impact of the mutations on the structure and function of the AIRE protein. The results of sequencing showed that heterozygous mutation c.622G>T (p.G208W) in exon 5 of the AIRE gene was detected in the patient and was a novel mutation, which had not been reported in the HGMD database and latest articles. This mutation was not detected in the 50 unrelated normal controls. The novel mutation of c.622G>T (p.G208W) in AIRE gene might play an important role in the pathogenesis of this case of autoimmune polyendocrinopathy syndrome type I.

A dominant CD4(+) T-cell response to Helicobacter pylori reduces risk for gastric disease in humans.

BACKGROUND & AIMS: Immunodominance is an important feature of antiviral, antitumor, and antibacterial cellular immune responses, but it is not well demonstrated in the immune responses against Helicobacter pylori. Antigen-specific CD4(+) T cells protect mice against infection with H pylori. We investigated the immunodominant CD4(+) T-cell response to neuraminyllactose-binding hemagglutinin (HpaA), which is a conserved, H pylori-specific colonization factor that is being investigated as an antigen for vaccination strategies. METHODS: HpaA-specific CD4(+) T cells were expanded with autologous peripheral blood mononuclear cells that had been incubated with recombinant HpaA and characterized using overlapping synthetic peptides. We compared the percentage of CD4(+) T cells with specificity for HpaA(88-100), restricted to HLA-DRB1*1501, among 59 H pylori-infected subjects with different gastric diseases. RESULTS: We identified and characterized several immunodominant CD4(+) T-cell epitopes derived from HpaA. The immunodominant CD4(+) T-cell responses specific to HpaA(88-100) were observed in most H pylori-infected individuals who expressed HLA-DRB1*1501 and were significantly more abundant in patients with less severe diseases (P < .05). CONCLUSIONS: The HLA-DRB1*1501-restricted immunodominant CD4(+) T-cell response to HpaA(88-100) is associated with reduced risk of severe gastric diseases. Further study of these and other immunodominant CD4(+) T-cell responses to H pylori will provide insight into mechanisms of protective immunity and aid in vaccine design.

Experimental investigation of the influence of mine water on mechanical properties of resin grout.

Resin grout is widely used in geotechnical and underground engineering, and is often affected by different mine water solutions. This study considered the effects of different mine water solutions and soaking times on resin grout. Soaking tests and uniaxial compression tests were conducted to investigate the changes in the solution pH, relative specimen mass, and uniaxial compressive strength (UCS), and the deterioration of the resin grout's mechanical properties caused by the mine water solution was analyzed. The corrosion mechanism of resin grout under the action of different mine water solutions was investigated through scanning electron microscopy tests. The results reveal that the pH value of the solution and the relative mass of the specimen gradually stabilized as the soaking time was extended, and the final solution was weakly alkaline. The increase in the acidity and alkalinity of the solution and the extension of the soaking time led to a gradual decrease in the UCS and elastic modulus of resin grout under the action of mine water. As the soaking was prolonged, the resin grout properties deteriorated to different degrees and Poisson's ratio increased. Moreover, owing to the different types and degrees of mine water action on resin grout in different mine water environments, the changes in the resin grout microstructure were also different. The defined damage parameters can express the damage process of the resin grout's UCS quantitatively under the action of mine water solution. Finally, beneficial engineering application countermeasures are proposed for different resin grout types used in roadway support applications in coal mines.

Research progress on the content and distribution of rare earth elements in rivers and lakes in China.

This study reviewed the content and distribution of rare earth elements (REE) in rivers and lakes in China based on the online literature. The sequence distribution of REE presented the decreasing trends in the order: of Ce > La > Nd > Pr > Sm > Gb > Dy>Er > Yb > Eu > Lu > Ho > Tb > Tm in rivers water. Pearl River and the Jiulong River constitute a significant sediments REE reservoir with an average value mean of 229.6 mg/kg and 266.86 mg/kg, respectively; both have higher concentrations than the global river average (174.8 mg/kg) and higher than the local soil background (Chinese soil background). The Liaohe River is one of China's most polluted rivers, with REE distribution ranging from 106.61 to 174.71 g/L (average 144.59 g/L in water). The total concentrations of dissolved REE in rivers near REE mining areas in China are higher than in other rivers. Increasing anthropogenic inputs to natural systems may permanently alter the natural signatures of REE. The distribution characteristics of REE in Chinese lakes (sediments) varied greatly, and the mean enrichment factor (EF) was sorted as follows: Ce > La > Nd > Pr > Sm > Gd > Dy>Er > Yb > Eu > Ho > Tb > Tm > Lu, where Ce was the most abundant followed by La, Nd, and Pr, and these four elements account for 85.39 % of the total concentration of REE. The REE in the sediments obtained from Poyang Lake and Dongting Lake had an average concentration respectively of 254.0 µg/g and 197.95 µg/g; both are considerably higher than the average upper continental crust (146.4 µg/g) and higher than in other lakes in China and around the world. The distribution and accumulation of LREE in most lake sediments result from the joint action of human activities and natural processes. It concluded that mining tailings were the primary cause of REE pollution in sediments, and industrial and agricultural activities are mainly responsible for water contamination.

Whole Transcriptome Sequencing of Peripheral Blood Shows That Immunity/GnRH/PI3K-Akt Pathways Are Associated With Opioid Use Disorder.

Background: Opioid use disorder (OUD), which is most commonly exhibited as addiction, is a persistent chronic disease that places a burden on families and society. Various peripheral traits have been linked to OUD in the past, but research on this topic is insufficient. Methods: Seven male patients with OUD and 7 male healthy controls with matched demographic and clinical data were enrolled in this study. Peripheral blood RNA was used to construct an rRNA-removed library and a small RNA library. The peripheral transcriptomic differences between the two groups were investigated using RNA-seq. Differentially expressed messenger RNAs (mRNAs), long non-coding RNAs (lncRNAs), circular RNAs (circRNAs) and microRNAs (miRNAs) were identified by bioinformatics methods, and functional enrichment analysis with differentially expressed RNAs was performed to investigate the potential biological mechanisms of OUD. Results: A total of 229 mRNAs (115 upregulated, 114 downregulated), 416 lncRNAs (191 upregulated, 225 downregulated), 17 circRNAs (16 upregulated, 1 downregulated) and 74 miRNAs (42 upregulated, 32 downregulated) were differentially expressed between the OUD group and the healthy control group. Functional enrichment analysis with differentially expressed mRNAs showed that immunity, GnRH secretion, and PI3K-Akt signaling pathways were associated with OUD. Immunity-, JAK-STAT-, and insulin-related pathways were enriched in functional enrichment analysis of target genes predicted by differentially expressed miRNAs. Conclusion: We identified hundreds of differentially expressed genes that were enriched in immunity, GnRH secretion and PI3K-Akt signaling pathways. Some genes with significant changes might be used as potential biomarkers for progression and treatment of OUD.

Impact of living donor liver with steatosis and idiopathic portal inflammation on clinical outcomes in pediatric liver transplantation: Beijing experience.

Background: To evaluate the impact of steatosis and/or idiopathic portal inflammation (IPI) in living donor livers on recipients' clinical outcomes. Methods: We assessed 305 qualified donor liver samples from June 2013 to December 2018. Donors and recipients' clinical characteristics, including follow-up data were retrieved. The graft and overall survival with/without steatosis or portal inflammation were compared by Kaplan-Meier analysis. Results: For living donors, the medium age of was 31.2 (28, 35.8) years old; liver histopathology showed macrovesicular steatosis: 0-5% 264/305 (86.6%) and 5-30% 41/305 (13.4%), IPI: no 220/305 (72.1%) and mild 85/305 (27.9%). For recipients, the medium age was 1.0 (0.6, 1.5) years old; the median pediatric-end-stage-liver-disease score was 16 (5.0, 26.0) and medium follow-up time was 32.8 (24.8, 52.0) months. Biliary atresia (69.5%) was the main indication for liver transplantation (LT). Conclusions: The presence of steatosis and portal inflammation of the donor liver did not impact the clinical outcomes including transaminase or bilirubin normalization, short-/long-term complications and recipients' survival. However, recipients with high pediatric-end-stage-liver-disease score (>16) receiving donor liver with portal inflammation, but not steatosis, had trend negative effect on recipients' survival. In conclusion, donor livers with mild steatosis and portal inflammation were qualified for pediatric living donor LT. However, donor liver with mild portal inflammation would better not be allocated to recipients with high pediatric-end-stage-liver-disease score. This study provided new evidence in pediatric living donor liver allocation.

A regenerable ion-imprinted magnetic biocomposite for selective adsorption and detection of Pb2+ in aqueous solution.

A regenerable ion-imprinted magnetic biocomposite (IIMB) was successfully synthesized for simultaneous removal of Pb2+ using Serratia marcescens and carboxymethyl chitosan (CMC) as functional carriers, Pb2+ was utilized as the imprinted ion, while Fe3O4 served as the magnetic component. The structure and properties of IIMB were characterized by various techniques. The adsorption kinetics, isotherms and thermodynamics were applied to interpret the Pb2+ adsorption process on IIMB. The results showed the IIMB possessed prominent uptake ability toward Pb2+. The pseudo-second-order kinetic (R2 = 0.9989) and Langmuir models (R2 = 0.9555) fitted the data well. Adsorption thermodynamics revealed that the adsorption was a spontaneous endothermic reaction. The possible adsorption mechanisms involved physical adsorption, electrostatic attraction and complexing. Moreover, because Pb2+ can be specifically and strongly adsorbed on IIMB, a simple method for detection of Pb2+ was established by coupling IIMB with flame atomic absorption spectrometry (IIMB-FAAS). The developed IIMB-FAAS assay can sensitively detect Pb2+ with a linear range from 5.0 to 500.0 µg/L. The detection limit (LOD) of 0.95 µg/L as well as a quantification limit (LOQ) of 3.20 µg/L were obtained. This work proved that the IIMB could selective and efficient adsorb Pb2+, which provided some insights into wastewater treatment, water quality inspection and environmental remediation.

Positive Urine Morphine Test in a Chinese Patient Receiving Methadone Maintenance Treatment After Eating Hot Pot: A Case Report.

Poppy shells contain opioids. It is a popular, but illegal spice in China. If these shells are added to food, urine morphine test of the patients involved in methadone maintenance treatment (MMT) can turn out positive. A 44-year-old male patient, who had been receiving MMT for 12 years with an extremely good treatment adherence, presented with positive urine morphine test in routine clinical compliance monitoring. However, the patient denied the use of any opioids recently. Coincidently, all of his four family members (none with a history of heroin abuse) showed positive results in urine morphine test. Considering that all these people ate a hot pot together a day before the test added to the speculation that the positive result could be due to the addition of poppy shell to the hot pot. Based on our results, we propose that this unusual phenomenon is worthy of clinical attention when managing patients at MMT clinics.

High-efficient and sustainable biodegradation of microcystin-LR using Sphingopyxis sp. YF1 immobilized Fe3O4@chitosan.

The microcystin-LR (MC-LR) produced due to harmful cyanobacterial blooms have brought great harm to human and aquatic organisms, attracting a wide public health attention. To deal with MC-LR contamination, we synthesized a novel bio-functionalized composite for the high-efficient and sustainable biodegradation of microcystin-LR by covalent immobilizing Sphingopyxis sp. YF1 onto chitosan-grafted Fe3O4 magnetic particles (Fe3O4@CTS). The Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM) were utilized to characterize the structural properties of Fe3O4@CTS/Sphingopyxis sp. YF1. The immobilization conditions were optimized. And the MC-LR-degrading capabilities of Fe3O4@CTS/Sphingopyxis sp. YF1 were assessed under various conditions. The results showed that the optimal immobilization conditions containing 1.0 % (v/v) glutaraldehyde, immobilization for 4 h at 30 ℃. The Fe3O4@CTS/Sphingopyxis sp. YF1 showed an attractive degradation performance which possesed a wide torlerance to pH (6.0-9.0) and temperature (25-35 ℃). More interesting is that the Fe3O4@CTS/Sphingopyxis sp. YF1 exhibited significantly increased MC-LR-degrading capabilities after recycling and reusing which degradation rate reached 1.50 µg/mL/h in the sixth cycle, and it was easily recycled by using a magnet (Ms 21.5 emug-1). Two intermediates (tetrapeptide and Adda) and three degradation related genes (mlrA, mlrB and mlrC) were obtained in this study and the pathway for the degradation was proposed. These results revealed that Fe3O4@CTS/Sphingopyxis sp. YF1 can be potentially used for treatment of MC-LR contaminated environment.

Optimization on preparation of Fe3O4/chitosan as potential matrix material for the removal of microcystin-LR and its evaluation of adsorption properties.

Adsorbent Fe3O4/chitosan was successfully synthesized for the removal of microcystin-LR and characterized by Scanning electron microscope, Fourier transform infra-red, thermogravimetric analysis and vibrating sample magnetometer. The effects of reaction conditions, including pH, temperature and ratio of Fe3O4 to chitosan on microcystin-LR adsorption capacity were investigated by the Box-Behnken response surface methodology design, and the optimal adsorption conditions were determined. The adsorption properties of microcystin-LR were examined by adsorption kinetics, isothermal and thermodynamics experiments. The results demonstrated that Fe3O4/chitosan was successfully prepared and the maximum adsorption capacity of microcystin-LR was under optimum conditions in which pH value was 5.53, temperature was 40 °C and the ratio of Fe3O4 to chitosan was 1:1.39. The data revealed that kinetics was fitted well with the pseudo-second-order model, Langmuir isotherm model was more appropriate for describing than the Freundlich isotherm model and the adsorption of microcystin-LR was a spontaneous process. The material maintained good adsorption capacity after five cycles. The results suggested that Fe3O4/chitosan was an efficient and low-cost adsorbent for removing microcystin-LR from polluted water.

Biodegradation of microcystin-RR and nutrient pollutants using Sphingopyxis sp. YF1 immobilized activated carbon fibers-sodium alginate.

A novel biological material named activated carbon fibers-sodium alginate@Sphingopyxis sp. YF1 (ACF-SA@YF1) was synthesized for microcystin-RR (MC-RR) and nutrient pollutant degradation in eutrophic water. The synthesized biomaterial was characterized by scanning electron microscopy (SEM). Box-Behnken design and response surface methodology (RSM) were utilized for the optimization of conditions during the MC-RR degradation. The degradation of MC-RR and nutrient pollutants was dynamically detected. The results revealed that the optimal conditions were temperature 32.51 °C, pH 6.860, and inoculum 14.97%. The removal efficiency of MC-RR, nitrogen, phosphorus, and chemical oxygen demand were 0.76 µg/mL/h, 32.45%, 94.57%, and 64.07%, respectively. In addition, ACF-SA@YF1 also performed satisfactory cyclic stability, while the MC-RR removal efficiency was 70.38% after seven cycles and 78.54% of initial activity after 20 days of storage. Therefore, it is reasonable to believe that ACF-SA@YF1 is an effective material which has a great prospect in removing MC-RR and nutrients from freshwater ecosystems.

Efficient removal of Pb(II) from aqueous solution by a novel ion imprinted magnetic biosorbent: Adsorption kinetics and mechanisms.

It is vital to understand the adsorption mechanisms and identify the adsorption kinetics when applying an adsorbent to remove heavy metals from aqueous solution. A Pb(II) imprinted magnetic biosorbent (Pb(II)-IMB) was developed for the removal of Pb2+ via lead ion imprinting technology and crosslinking reactions among chitosan (CTS), Serratia marcescens and Fe3O4. The effect of different parameters such as solution pH, adsorbent dosage, selectivity sorption and desorption were investigated on the absorption of lead ion by Pb(II)-IMB. The adsorbent was characterized by a Brunauer-Emmett Teller (BET) analysis, X-ray diffraction (XRD), vibrating sample magnetometry (VSM), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The adsorption kinetics, equilibrium and thermodynamics of Pb(II)-IMB for Pb(II) were studied. The results of the abovementioned analyses showed that the adsorption kinetic process fit well with the second-order equation. The adsorption isotherm process of Pb(II) on the Pb(II)-IMB was closely related to the Langmuir model. Thermodynamic studies suggested the spontaneous and endothermic nature of adsorption of Pb(II) by Pb(II)-IMB. The adsorption mechanism of Pb(II)-IMB was studied by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The results indicated that the nitrogen in the amino group and the oxygen in the hydroxyl group of Pb(II)-IMB were coordination atoms.

Polymer nanosheets derived porous carbon nanosheets as high efficient electrocatalysts for oxygen reduction reaction.

Porous carbon nanosheets and corresponding heteroatom doped porous carbon nanosheets have shown great potential as active materials for energy conversion and storage in recent years. However, it remains great challenge to prepare such kind of new two-dimensional (2D) polymer nanosheets without using any templates. In this work, thiadiazole-containing expanded heteroazaporphyrinoid was designed as the building blocks for preparation of free-standing N/S-containing polymer nanosheets (PN) without using any templates. Most importantly, such PN can coordinate with transition metal ions to prepare Fe, N, and S containing PN-Fe. By using these PN-Fe as precursors, Fe/N/S co-doped porous carbon nanosheets (PCN-FeNS) can be facilely prepared by direct pyrolysis under inert condition. The N and S contents of PCN-FeNS can reach up to 6.4 at.% and 0.8 at.%, respectively. For proof-of-concept, PCN-FeNS were further used as electrochemical catalysts for oxygen reduction reaction (ORR) in both alkaline and neutral media. Benefiting from the high surface area and rich-doping character, PCN-FeNS exhibited relatively high half-wave potential of down to 0.71 V, via a four-electron transfer mechanism (n = 3.87 at 0.65 V), as well as high diffusion limiting current density (JL = 5.02 mA cm-2), which are comparable to commercial precious metal based electrocatalysts. This study not only offers a new method to prepare conjugated polymer nanosheets, but also provides a new strategy to fabricate Fe/N/S co-doped porous carbon nanosheets for versatile energy-related applications.

Physiological investigation of C4-phosphoenolpyruvate-carboxylase-introduced rice line shows that sucrose metabolism is involved in the improved drought tolerance.

We compared the drought tolerance of wild-type (WT) and transgenic rice plants (PC) over-expressing the maize C4PEPC gene, which encodes phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) gene, and evaluated the roles of saccharide and sugar-related enzymes in the drought response. Pot-grown seedlings were subjected to real drought conditions outdoors, and the yield components were compared between PC and untransformed wild-type (WT) plants. The stable yield from PC plants was associated with higher net photosynthetic rate under the real drought treatment. The physiological characters of WT and PC seedlings under a simulated drought treatment (25% (w/v) polyethylene glycol-6000 for 3 h; PEG 6000 treatment) were analyzed in detail for the early response of drought. The relative water content was higher in PC than in WT, and PEPC activity and the C4-PEPC transcript level in PC were elevated under the simulated drought conditions. The endogenous saccharide responses also differed between PC and WT under simulated drought stress. The higher sugar decomposition rate in PC than in WT under drought analog stress was related to the increased activities of sucrose phosphate synthase, sucrose synthase, acid invertase, and neutral invertase, increased transcript levels of VIN1, CIN1, NIN1, SUT2, SUT4, and SUT5, and increased activities of superoxide dismutase and peroxidase in the leaves. The greater antioxidant defense capacity of PC and its relationship with saccharide metabolism was one of the reasons for the improved drought tolerance. In conclusion, PEPC effectively alleviated oxidative damage and enhanced the drought tolerance in rice plants, which were more related to the increase of the endogenous saccharide decomposition. These findings show that components of C4 photosynthesis can be used to increase the yield of rice under drought conditions.