Frontiers and future of immunotherapy for pancreatic cancer: from molecular mechanisms to clinical application.

Pancreatic cancer is a highly aggressive malignant tumor, that is becoming increasingly common in recent years. Despite advances in intensive treatment modalities including surgery, radiotherapy, biological therapy, and targeted therapy, the overall survival rate has not significantly improved in patients with pancreatic cancer. This may be attributed to the insidious onset, unknown pathophysiology, and poor prognosis of the disease. It is therefore essential to identify and develop more effective and safer treatments for pancreatic cancer. Tumor immunotherapy is the new and fourth pillar of anti-tumor therapy after surgery, radiotherapy, and chemotherapy. Significant progress has made in the use of immunotherapy for a wide variety of malignant tumors in recent years; a breakthrough has also been made in the treatment of pancreatic cancer. This review describes the advances in immune checkpoint inhibitors, cancer vaccines, adoptive cell therapy, oncolytic virus, and matrix-depletion therapies for the treatment of pancreatic cancer. At the same time, some new potential biomarkers and potential immunotherapy combinations for pancreatic cancer are discussed. The molecular mechanisms of various immunotherapies have also been elucidated, and their clinical applications have been highlighted. The current challenges associated with immunotherapy and proposed strategies that hold promise in overcoming these limitations have also been discussed, with the aim of offering new insights into immunotherapy for pancreatic cancer.

Comprehensive comparison between conservative therapy and surgical management for completely displaced and comminuted mid-shaft clavicle fractures.

PURPOSE: It is still controversial whether complete displaced mid-shaft clavicle fractures should be treated with internal fixation or conservative therapy. This retrospective study aims to compare clinical outcomes of two treatment protocols. MATERIALS AND METHODS: 105 patients with displaced and comminuted mid-shaft clavicle fractures were included in this study, among which 55 patients were treated conservatively and 50 patients accepted surgical fixation and were followed up for over 20 months on average. Rate of union, malunion, time taken for union, functional outcome, self-reported satisfaction and complications were compared. RESULTS: Union rate of operative group (n=49, 98.0%) was higher than the non-operative group (n=48, 87.3%). Time taken for union in operative group (2.37±1.06 months) was shorter than the non-operative group (3.69±1.01 months). Malunion and asymmetric were only seen in the conservative group. Numbness of the shoulder was only reported in the operative group (n=23, 46.0%). Most of patients in the operative group (n=45, 90%) accepted a second operation to remove the implant. No statistically difference was found in self-reported satisfaction, Quick-DASH and Constant-Murley score. The operative group returned to work faster (1.47±0.89 to 3.34±1.37 months), regained full range of motion earlier (1.66±0.78 to 3.83±1.24 months) and regained strength faster (3.86±2.45 to 8.03±2.78 months) than the non-operative group. CONCLUSION: Complete displaced and comminuted mid-shaft clavicle fractures treated surgically have more reliable union and faster recovery when compared to conservatively treated fractures.

Design and discovery of novel pyrazole-pyrrolopyrimidine derivatives as anti-glioma agents via promoting apoptosis, inhibiting cell cycle and EGFR-TK.

Glioma is an aggressive type of brain malignancy responsible for significant morbidity and mortality. In the current scenario, epidermal growth factor receptor (EGFR) kinases targeted therapy showed significant benefits in glioma patients. Therefore, in the present study, we intend to investigate the anti-glioma potential of a novel class of pyrazole-pyrrolopyrimidine derivatives and their mechanism of action. The compounds will be synthesized in a straight-forward synthetic route in excellent yields and subsequently tested for EGFR kinase inhibition. The compounds showed a diverse range of inhibitory activity against EGFR (IC50 = 3.4-873.2 nM). With an IC50 of 1.5 nM, compound 4i was determined to be the most effective EGFR inhibitor, even superior to the standard erlotinib (IC50 2.3 nM). Among them, the three most potent compounds (4i, 4j, and 4k) were further subjected to the anticancer activity against the panel of various cancer cell lines MCF-7 (breast cancer), A549 (lung cancer), U87 (glioblastoma cell)-EGFR-Wild Type, U87 (mutant glioblastoma cells) EGFR-mutant cell, MCF-12A (normal cells). The compound 4i showed the most potent activity against glioblastoma cells as compared to other cancer cells. The effect of compound 4i was also studied on the apoptosis of U87 cells, where it showed induction of apoptosis in a concentration-dependent manner. It also showed inhibition of the G2/M cell cycle phase of U87 cells. Our study demonstrated the development of novel pyrazole-pyrrolopyrimidine derivatives as a novel class of anti-glioma agents.

[Estimation of Cropland Nitrogen Runoff Loss Loads in the Yangtze River Basin Based on the Machine Learning Approaches].

A quantitative understanding of cropland nitrogen (N) runoff loss is critical for developing efficient N pollution control strategies. Using correlation analysis, a structural equation model, variance decomposition, and machine learning methods, this study identified the primary influencing factors of total N (TN) runoff loss from uplands (n=570) and paddy (n=434) fields in the Yangtze River Basin (YRB) and then developed a machine learning-based prediction model to quantify cropland N runoff loss load. The results indicated that runoff depth, soil N content, and fertilizer addition rate were the major influencing factors of TN runoff loss from uplands, whereas TN runoff loss rate from paddy fields was mainly regulated by runoff depth and fertilizer addition rate. Among the four used machine learning methods, the prediction models based on the random forest algorithm presented the highest accuracy (R2=0.65-0.94) for predicting upland and paddy field TN runoff loss rates. The random forest algorithm based model estimated a total cropland TN loss load in the YRB of 0.47 Tg·a-1 (upland:0.25 Tg·a-1; paddy field:0.22 Tg·a-1) in 2013, with 58% of TN runoff loss load derived from the midstream and downstream regions. The models predicted that TN runoff loss loads from croplands in YRB would decrease by 2.4%-9.3% for five scenarios, with higher TN load reductions occurring from scenarios with decreased runoff amounts. To mitigate cropland N nonpoint source pollution in YRB, it is essential to integrate efficient water, fertilizer, and soil nutrient managements as well as to consider the midstream and downstream regions as the high priority area. The machine learning-based modeling method developed in this study overcame the difficulty of identifying the functional relationships between cropland TN loss rate and multiple influencing factors in developing relevant prediction models, providing a reliable method for estimating regional and watershed cropland TN loss load.

Cell-based and cell-free immunotherapies for glioblastoma: current status and future directions.

Glioblastoma (GBM) is among the most fatal and recurring malignant solid tumors. It arises from the GBM stem cell population. Conventional neurosurgical resection, temozolomide (TMZ)-dependent chemotherapy and radiotherapy have rendered the prognosis of patients unsatisfactory. Radiotherapy and chemotherapy can frequently induce non-specific damage to healthy brain and other tissues, which can be extremely hazardous. There is therefore a pressing need for a more effective treatment strategy for GBM to complement or replace existing treatment options. Cell-based and cell-free immunotherapies are currently being investigated to develop new treatment modalities against cancer. These treatments have the potential to be both selective and successful in minimizing off-target collateral harm in the normal brain. In this review, several aspects of cell-based and cell-free immunotherapies related to GBM will be discussed.

Inhibition of STAT3 signaling as critical molecular event in HUC-MSCs suppressed Glioblastoma Cells.

Objective: We investigated the effect of human umbilical cord mesenchymal stem cells (HUC-MSCs) supernatants on proliferation, migration, invasion, and apoptosis in glioblastoma (GBM) cell lines RG-2, U251, U87-MG, and LN-428, as well as their apoptosis and autophagy-mediated through IL-6/JAK2/STAT3 signaling pathway to explore the molecular mechanisms. Methods: In this study, RG-2, U251, U87-MG, and LN-428 cells were treated with 9 mg/ml HUC-MSCs supernatants. Their responses to HUC-MSCs supernatants treatment and the status of STAT3 signaling were analyzed by multiple experimental approaches to elucidate the importance of HUC-MSCs supernatants for GBM. Results: The results demonstrated that after treatment with HUC-MSCs supernatants, in vitro proliferation of RG-2, U251, U87-MG, and LN-428 cells were inhibited, and their sustained growth was also blocked. RG-2, U251, and U87-MG cells showed significant S phase accumulation, while LN-428 cells were blocked in G0/G1 phase. Their migratory invasive capacities were inhibited, and their apoptosis and autophagy ratios were increased. These effects were mediated through the IL-6/JAK2/STAT3 and its downstream signaling pathway. Conclusion: Our data showed that HUC-MSCs supernatants had anti-tumor effects on GBM cells. It inhibited the proliferation, migration, and invasion of GBM cells and promoted their apoptosis. Negative regulation of the IL-6/JAK2/STAT3 signaling pathway enhanced apoptosis and autophagy in tumor cells, thereby improving the therapeutic effect on GBM.

Ba3.5Cu7.55In1.15Se9: A Wide-Bandgap Copper Indium Selenide Reveals Strong Luminescence and Third-Harmonic Generation.

A new copper indium selenide, Ba3.5Cu7.55In1.15Se9, was synthesized by the KBr flux reaction at 800 °C. The compound crystallizes with orthorhombic Pnma, a = 46.1700(12) Å, b = 4.26710(10) Å, c = 19.8125(5) Å, and Z = 8. The structural framework mainly consists of four sites of cubane-type defective M4Se3 (M = Cu, Cu/In) units with disordered Cu+/In3+ ions present at the part corner of each unit. The single crystal emits intense photoluminescence at 657 nm with a relative quantum yield (RQY) 0.2 times that of rhodamine 6G powder. The compound belongs to a direct band gap at 1.91 eV, analyzed by Tauc's plot, and the energy is close to the PL position. The Hall effect measurement on a pressed pellet reveals an n-type conductivity with a carrier concentration of 3.358 × 1017 cm-3 and a mobility of 24.331 cm2 V-1 s-1. Furthermore, the compound produces a strong nonlinear third-harmonic generation (THG), with an χS(3) value of 1.3 × 105 pm2/V2 comparable to 1.6 × 105 pm2/V2 for AgGaSe2 measured at 800 nm.

Temperature-triggered fluorocopolymer aggregate coating switching from antibacterial to antifouling and superhydrophobic hemostasis.

The multifunction antibacterial hemostatic materials can reduce blood loss, infection and wound complications, which probably decrease morbidity and health care costs. However, the contradictory relationship between antibacterial ability and biocompatibility, and the unnecessary blood loss restricts the practical application of hydrophilic cationic antibacterial hemostatic materials. Herein, a multifunctional temperature-triggered antibacterial hemostatic fluorocopolymer aggregate coating was developed. After self-assembly and quaternization process, the quaternized poly(N,N-dimethylaminoethylmethacrylate)-b-poly(1H,1H,2H,2H-heptadecafluorodecyl acrylate) block copolymers (PDMA-b-PFOEMA) aggregate coating consisting of fluoropolymer and quaternary ammonium salt were built. The synergistic effect on fluorinated block with low surface energy and quaternary ammonium salt block with bactericide activity severs the way of initial bacterial attachment and proliferation, while the migration of fluorinated block greatly promotes the biocompatibility and anti-adhesion performance in response to the switch from room temperature to physiological temperature. Furthermore, the fluorocopolymer aggregate coating with hydrophobic properties possessed the property of rapid coagulation, low blood loss, minor secondary bleeding and least bacteria infiltration. The multifunctional temperature-triggered fluorocopolymer aggregate coating with antifouling, antibacterial and hemostatic properties may have a great potential in the biomedical application.

[Estimation of Nitrous Oxide Emission from River System Based on Water Discharge and Dissolved Nitrous Oxide Concentration].

Due to increasing active nitrogen pollution loads, river systems have become an important source of nitrous oxide (N2O) in many areas. Due to the lack of monitoring data in many studies as well as the difficulty in estimating intermediate parameters and expressing temporal-spatial variability in current methods, a high level of uncertainty remains in the estimates of riverine N2O emission quantity. Based on the monthly monitoring efforts conducted for 10 sampling sites across the Yonganxi River system in Zhejiang Province from June 2016 to July 2019, the temporal and spatial dynamics of riverine N2O dissolved concentrations ρ(N2O), N2O fluxes, and their influencing factors were addressed. A multiple regression model was then developed for predicating riverine N2O emission flux to estimate annual N2O emission quantity for the entire river system. The results indicated that observed riverine ρ(N2O) (0.03-2.14 µg·L-1) and the N2O fluxes[1.32-82.79 µg·(m2·h)-1] varied by 1-2 orders of magnitude of temporal-spatial variability. The temporal and spatial variability of ρ(N2O) were mainly influenced by the concentrations of nitrate, ammonia, and dissolved organic carbon, whereas the N2O emission fluxes were mainly affected by river water discharges and ρ(N2O). A multiple regression model that incorporates variables of river water discharge and ρ(N2O) could explain 90% of the variability in riverine N2O emission fluxes and has high accuracy. The model estimated N2O emission quantity from the entire Yonganxi River system of 3.67 t·a-1, with 29% from the main stream and 71% from the tributaries. The IPCC default emission factor method might greatly overestimate and underestimate N2O emission quantities for rivers impacted by low and high pressures of human activities, respectively. This study advances our quantitative understanding of N2O emission for the entire river system and provides a reference method for estimating riverine N2O emission with more accuracy.

Noninvasive evaluation of intracranial pressure in patients with traumatic brain injury by transcranial Doppler ultrasound.

INTRODUCTION: The purpose of this study was to investigate the relationship between pulsatility index (PI) or optic nerve sheath diameter (ONSD) and intracranial pressure (ICP) in patients with traumatic brain injury (TBI), and the ability of ONSD and ICP to predict intracranial hypertension. METHODS: A total of 68 patients with TBI were included in this retrospective study. After receiving surgery treatment, they underwent transcranial Doppler ultrasound (TCD). The statistical correlation between PI or ONSD and ICP 1 week after surgery was analyzed. Furthermore, the areas under the curve (AUCs) of ONSD or PI or a combination of them were calculated to predict intracranial hypertension. RESULTS: There was a correlation between ONSD and ICP. This correlation still remained at ONSD ≥ 5 mm. Furthermore, there was a strong correlation between PI and ICP. There was a moderate correlation between ICP and PI on days 3, 4, and 5 after surgery (r = 0.508, p < .001), and a strong correlation on days 6 and 7 after surgery (r = 0.645, p < .001). Moreover, for predicting intracranial hypertension with PI ≥ 1.2 mm or ONSD ≥ 5 mm or a combination of them, the AUC was 0.729, 0.900, and 0.943, respectively (p < .001). CONCLUSIONS: The correlation between ONSD or PI and invasive ICP was different with different levels of ICP in different periods in patients with TBI after surgery. When ONSD ≥ 5 mm and PI ≥ 1.2, it could predict elevated ICP more accurately.

Risk Factors and Neurologic Outcomes in Patients with Traumatic Brain Injury and Coagulopathy Within 72 h After Surgery.

OBJECTIVE: The purpose of this study was to explore the effect of coagulopathy in patients with traumatic brain injury (TBI) during the early postoperative period. METHODS: The baseline characteristics, intraoperative management, and follow-up data of 462 patients with TBI between January 2015 and June 2019 were collected and retrospectively analyzed by multivariate logistic regression. Coagulopathy was defined as activated partial thromboplastin time > 40 s, international normalized ratio > 1.4, or platelet counts < 100×109/L. RESULTS: Multivariate logistic regression analysis revealed that the Glasgow Coma Scale (GCS) on admission, Injury Severity Score (ISS) on admission, pupil mydriasis, duration of surgery, intraoperative blood loss, and intraoperative crystalloid resuscitation were independent risk factors for patients who developed coagulopathy after surgery. There were statistical differences in mortality (p = 0.049), the Glasgow Outcome Scale-Extended (GCS-E; p = 0.024), and the modified Rankin Scale (p = 0.043) between the patients with and without coagulopathy 1 week after surgery. Coagulopathy within 72 h after surgery revealed the higher mortality at 1 week (66.7%), 3 months (71.4%), and 6 months (76.2%). Coagulopathy within 72 h after surgery in patients with a TBI predicted worse disease progression and unfavorable neurologic outcomes. CONCLUSION: Taking practical and reasonable measures to manage these risk factors may protect patients with TBI from postoperative coagulopathy.

Modeling Riverine N2O Sources, Fates, and Emission Factors in a Typical River Network of Eastern China.

Estimates of riverine N2O emission contain great uncertainty because of the lack of quantitative knowledge concerning riverine N2O sources and fates. Using a 3.5-year record of monthly N2O measurements from the Yongan River network of eastern China, we developed a mass-balance model to address the riverine N2O source and sink processes. We achieved reasonable model efficacies (R2 = 0.44-0.84, Nash-Sutcliffe coefficients = 0.40-0.80) across three tributaries and the entire river system. Estimated riverine N2O loads originated from groundwater (38-88%), surface runoff (3-26%), and in-stream production (4-48%). Estimated in-stream losses via atmospheric release + complete denitrification accounted for 76, 95, 25, and 89% of riverine N2O fate for the agricultural, residential, forest, and entire river system, respectively. Considering limited complete denitrification, the model estimated an upper-bound riverine N2O emission rate of 2.65 ton N2O-N km-2 year-1 for the entire river system. Riverine N2O emission estimates were of comparable magnitude to those estimated with a power-law scaling model. Riverine N2O emissions using the IPCC default emission factor (0.26%) overestimated emissions by 3-15 times, whereas the dissolved N2O concentration-based emission factor overestimated or underestimated emissions. This study highlights the importance of combining comprehensive information on N2O sources and fates to achieve accurate riverine N2O emission estimates.

Temozolomide chemotherapy combined with radiotherapy versus radiotherapy alone after surgery in patients with high-risk low-grade gliomas.

PURPOSE: The purpose of this study was to compare the clinical efficacy and safety of temozolomide (TMZ) combined with three-dimensional conformal radiotherapy (3D-CRT) and radiotherapy alone after surgery in patients with high-risk low-grade gliomas (LGGs). METHODS: Patients (N=110) with LGGs were enrolled. Patients receiving TMZ chemotherapy combined with radiotherapy were considered as combination group (n=55), while those treated with radiotherapy alone were regarded as control group (n=55). The patients were followed up, and the overall survival (OS) and progression-free survival (PFS) were recorded. Finally, factors possibly affecting prognosis were analyzed. RESULTS: The follow-up results exhibited median OS [(67.4±8.8) months vs. (63.9±8.6) months] and median PFS [(51.1±7.6) months vs. (46.8±6.9) months] as well as three-year OS rate and three-year PFS rate in combination group and control group. Log-rank test indicated that the difference in OS was not statistically significant between the two groups of patients, and PFS in combination group was significantly superior to that in control group. The results of univariate and multivariate analysis displayed that age <40 years old and complete tumor resection were independent factors affecting the three-year OS of patients with high-risk LGGs. Besides, age <40 years old, complete tumor resection and TMZ chemotherapy combined with radiotherapy after surgery were independent factors affecting the three-year PFS of patients with high-risk LGGs. CONCLUSION: TMZ chemotherapy combined with radiotherapy after surgery in patients with high-risk LGGs can prominently improve clinical efficacy, prolong PFS, and facilitate tolerance to adverse reactions, but not prolong the OS of patients. The OS is notably prolonged in patients aged <40 years old and receiving complete tumor resection.

National estimates of environmental thresholds for upland soil phosphorus in China based on a meta-analysis.

The environmental threshold for upland soil phosphorus (P) content (ETSP, i.e., inflection point of soil P content leading to enhanced P loss) provides an important metric for guiding agricultural nonpoint source P pollution control. This study achieved the first meta-analysis to determine ETSP values for upland soils in China. The estimated national-level ETSP based on 472 field experimental observations of Olsen-P content and P loss rate was 30.1 ± 4.0 mg P kg-1, which was lower than the average ETSP value (52.1 ± 5.0 mg P kg-1) but higher than the average agronomic threshold values (16.0 ± 6.4 mg P kg-1) previously reported. Lower upland ETSP values occurred in acidic soils and soils having higher organic matter content (SOM), precipitation and slope (ETSP: 30.5 for pH < 7.0 versus 46.1 for pH ≥ 7.0; >56.4 for SOM < 2%, 49.9 for SOM = 2%-3%, and <3 for SOM > 3%; 33 for precipitation < 1000 mm yr-1, 27.5 for precipitation = 1000-1200 mm yr-1 and <5 for precipitation > 1200 mm yr-1; and 39.8 for slopes < 5° versus <9 for slopes ≥ 5°). A multiple regression model that incorporates SOM, pH, precipitation and slope was developed to predict upland ETSP values (R2 = 0.73, p < 0.01). The model estimated national upland ETSP values ranging from ~0 to 100 mg P kg-1 with an areal-weighted average of 60.6 mg P kg-1 and 15% of national upland soils having ETSP values <30 mg P kg-1. Upland soil P contents in Guangdong, Fujian and Zhejiang provinces largely exceeded their corresponding ETSP values by 1-22 mg P kg-1, indicating high P loss risks. Controlling upland P loss requires integrated management of soil P content, SOM, pH and erosion control. This study provides the first national estimate of upland soil ETSP, providing critical quantitative information for designing management practices to attenuate agricultural nonpoint source P pollution.

Effect of low-level ultrasound treatment on the production of L-leucine by Corynebacterium glutamicum in fed-batch culture.

Various process intensification methods were proposed to improve the yield, quality, and safety of fermented products. Here, we report the enhancement of L-leucine production by Corynebacterium glutamicum CP using ultrasound-assisted fed-batch fermentation. Response surface methodology was employed to optimize the sonication conditions. At an ultrasonic power density of 94 W/L, frequency of 25 kHz, interval of 31 min, and duration of 37 s, C. glutamicum CP produced 52.89 g/L of L-leucine in 44 h, representing a 21.6% increase compared with the control. The production performance of L-leucine was also improved under ultrasonic treatment. Moreover, the effects of ultrasound treatment on the fermentation performance of L-leucine were studied in terms of cell morphology, cell membrane permeability, and enzyme activity. The results indicate that ultrasonication is an efficient method for the intensification of L-leucine production by C. glutamicum CP.

Effect of fed-batch and chemostat cultivation processes of C. glutamicum CP for L-leucine production.

Most of the current industrial processes for L-leucine production are based on fermentation, usually in fed-batch operation mode. Although the culture technology has advanced in recent decades, the process still has significant drawbacks. To solve these problems, we investigated the effects of chemostat culture conditions on the production of L-leucine by Corynebacterium glutamicum CP. The dilution rate, the nitrogen source, and the carbon-nitrogen ratio of the medium were optimized. With the addition of ammonium acetate to the chemostat medium, the initial C/N ratio was adjusted to 57.6, and the L-leucine titer reached the highest level at the optimal dilution rate of 0.04 h-1. Compared with fed-batch culture, the L-leucine titer was reduced (from 53.0 to 24.8 g L-1), but the yield from glucose was increased by 10.0% (from 0.30 to 0.33 mol mol-1) and productivity was increased by 58.3% (from 1.2 to 1.9 g L-1 h-1). Moreover, the titer of the by-product L-alanine was significantly reduced (from 8.9 to 0.8 g L-1). In addition, gene expression levels and activity of key enzymes in the synthesis of L-leucine and L-alanine were analyzed to explain the difference of production performance between chemostat culture and fed-batch culture. The results indicate that chemostat culture has great potential to increase the industrial production of L-leucine compared to current fed-batch approaches.

Estimation of nitrogen runoff loss from croplands in the Yangtze River Basin: A meta-analysis.

Nitrogen (N) runoff loss from croplands due to excessive anthropogenic N additions is a principal cause of non-point source water pollution worldwide. Quantitative knowledge of regional-scale N runoff loss from croplands is essential for developing sustainable agricultural N management and efficient water N pollution control strategies. This meta-analysis quantifies N runoff loss rates and identifies the primary factors regulating N runoff loss from uplands (n = 570) and paddy (n = 434) fields in the Yangtze River Basin (YRB). Results indicated that total N (TN) runoff loss rates from uplands and paddy fields consistently increased from upstream to downstream regions. Runoff depth, soil N content and fertilizer addition rate (chemical fertilizer + manure) were the major factors regulating variability of TN runoff loss from uplands, while runoff depth and fertilizer addition rate were the main controls for paddy fields. Multiple regression models incorporating these influencing factors effectively predicted TN runoff loss rates from uplands (calibration: R2 = 0.60, n = 242; validation: R2 = 0.55, n = 104) and paddy fields (calibration: R2 = 0.70, n = 189; validation: R2 = 0.85, n = 82). Models estimated total cropland TN runoff loss load in YRB of 0.54 (95% Cl: 0.23-1.33) Tg, with 0.30 (95% Cl: 0.15-0.56) Tg from uplands and 0.24 (95% Cl: 0.08-0.77) Tg from paddy fields in 2017. Guangxi, Jiangxi, Fujian, Hunan and Henan provinces within the YRB were identified as cropland TN runoff loss hotspots. Models predicted that TN runoff loss loads from croplands in YRB would decrease by 0.8-13.7% for five scenarios, with higher TN load reductions occurring from scenarios with decreased runoff amounts. Reducing upland TN runoff loss should focus primarily on soil N utilization and runoff management, while reducing N fertilizer addition and runoff provided the most sensitive strategies for paddy fields. Integrated management of water, soil and fertilizer is required to effectively reduce cropland N runoff loss.

Chiral molecular imprinted sensor for highly selective determination of D-carnitine in enantiomers via dsDNA-assisted conformation immobilization.

In this paper, a novel approach was established on the basis of a molecularly imprinted technique with the aid of double-stranded deoxyribonucleic acid (dsDNA) embedded in a molecularly imprinted polymer (MIP) membrane as a new functional unit with chiral recognition for highly specific chiral recognition. The chiral molecules were immobilized and anchored in the cavities of the MIP membrane on the basis of the three-dimensional structure of a molecule determined by the functional groups, spatial characterization of the cavities of MIPs, and the spatial orientation with dsDNA embedded in MIPs. D-carnitine was selected as an example of a chiral molecular template, which intercalated into dsDNA immobilized on the gold electrode surface to form dsDNA-D-carnitine complex, and then the complex was embedded in the MIP during electropolymerization. After elution, the stereo-selective cavities were obtained. Our findings have shown that AAAA-TTTT base sequence had high affinity for D-carnitine intercalation. Combined with the electrochemical detection method, MIP sensor was prepared. The selectivity of the MIP sensor to ultratrace D-carnitine was significantly improved; the sensor had remarkable stereo-selectivity and highly chiral specific recognition to D-carnitine, and L-carnitine with a concentration of 10,000 times D-carnitine did not interfere with the detection of D-carnitine in the assay of raceme. The sensor also exhibited high sensitivity to ultratrace D-carnitine determination with a linear response to the concentration of D-carnitine in the range of 3.0 × 10-16 mol/L to 4.0 × 10-13 mol/L, with a detection limit of 2.24 × 10-16 mol/L. The mechanism of chiral recognition was studied, and result showed that apart from the recognition effect of imprinted cavities, dsDNA provided chiral selectivity to the spatial orientation of chiral molecules via the intercalation of chiral molecules with dsDNA and electrostatic interaction with groups of DNA base.