Nitrate transformation and source tracking of Yarlung Tsangpo River using a multi-tracer approach combined with Bayesian stable isotope mixing model.

Excessive levels of nitrate nitrogen (NO3--N) could lead to ecological issues, particularly in the Yarlung Tsangpo River (YTR) region located on the Qinghai Tibet Plateau. Therefore, it is crucial to understand the fate and sources of nitrogen to facilitate pollution mitigation efforts. Herein, multiple isotopes and source resolution models were applied to analyze key transformation processes and quantify the sources of NO3-. The δ15N-NO3- and δ18O-NO3- isotopic compositions in the YTR varied between 1.23‰ and 13.64‰ and -7.88‰-11.19‰, respectively. The NO3--N concentrations varied from 0.08 to 0.86 mg/L in the dry season and 0.20-1.19 mg/L during the wet season. Nitrification remained the primary process for nitrogen transformation in both seasons. However, the wet season had a widespread effect on increasing nitrate levels, while denitrification had a limited ability to reduce nitrate. The elevated nitrate concentrations during the flood season were caused by increased release of NO3- from manure & sewage (M&S) and chemical fertilizers (CF). Future endeavors should prioritize enhancing management strategies to improve the utilization efficiency of CF and hinder the direct entry of untreated sewage into the water system.

Profiling of serum oxylipins identifies distinct spectrums and potential biomarkers in young people with very early onset gout.

OBJECTIVE: Oxylipins modulate inflammation via complex pathways. The oxylipin profile in gout remains unexplored. In this study, we systemically profiled oxylipins in young men and identified new oxylipin biomarkers for clinical use in differentiating gout from hyperuricaemia. MATERIAL AND METHODS: Oxylipin profiling was performed in 90 men (30 very early onset gout, 30 asymptomatic hyperuricaemia [HU] and 30 normouricaemia [NU], all aged <20 years) divided into discovery and validation sample sets. The dataset was analysed based on orthogonal projection to latent structure-discriminant analysis. Correlation network and pathway enrichment were conducted to reveal potential oxylipin-involved pathways of gout. Candidate oxylipins were further evaluated and optimized in the validation cohort, and differential oxylipin biomarkers combined with or without serum urate were applied to construct diagnostic models. RESULTS: In discovery stage, 21 differential oxylipins in the gout vs HU comparisons and 14 differential oxylipins in the gout vs NU comparisons were discovered. Correlation network analysis was performed and 14(S)-HDHA (14S-hydroxy-4Z,7Z,10Z,12E,16Z,19Z-docosahexaenoic acid) was identified as a hub metabolite in both comparisons. Seven down-regulated oxylipins in the gout vs HU group and five down-regulated oxylipins in the gout vs NU group were validated. Diagnostic models were constructed with the above oxylipins, with 14(S)-HDHA alone having an area under the curve of 1 (95% CI, 1, 1) in both comparisons. CONCLUSIONS: Young men with very early onset gout have distinct oxylipin spectrums, especially those derived from arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid. Differential oxylipins could serve as candidate serum biomarkers in differentiating gout from hyperuricaemia.

Tunable phase-mismatched mid-infrared difference-frequency generation between 6 and 17†µm in CdTe.

In parametric conversion, phase-matching techniques such as birefringence and quasi phase-matching (PM) with the designed crystal angle or periodically poled polarities are employed to fulfill the requirement of momentum conservation. However, directly using phase-mismatched interactions in nonlinear media with large quadratic nonlinear coefficient remains unheeded. Here, for the first time to the best of our knowledge, we study the phase-mismatched difference-frequency generation (DFG) in an isotropic cadmium telluride (CdTe) crystal, with the comparison of other DFG processes based on birefringence-PM, quasi-PM, and random-quasi-PM. Long-wavelength mid-infrared (LWMIR) phase-mismatched DFG with an ultra-broadband spectral tuning range of 6-17 µm based on CdTe is demonstrated. Thanks to the giant quadratic nonlinear coefficient (∼109 pm/V) and good figure of merit in the parametric process, the output power up to 100 µW is obtained, which is comparable to or even better than the DFG output from a polycrystalline ZnSe with the same thickness facilitated by random-quasi-PM. A proof-of-concept demonstration in gas sensing of CH4 and SF6 is conducted based on the phase-mismatched DFG as a typical application. Our results demonstrate the feasibility of phase-mismatched parametric conversion in producing useful LWMIR power and ultra-broadband tunability in a simple and convenient way without the necessity of controlling the polarization, phase-matching angle, or pole periods, which could find applications in the fields of spectroscopy and metrology.

Lumbar MR-based radiomics nomogram for detecting minimal residual disease in patients with multiple myeloma.

OBJECTIVES: Minimal residual disease (MRD) is a standard for assessing treatment response in multiple myeloma (MM). MRD negativity is considered to be the most powerful predictor of long-term good outcomes. This study aimed to develop and validate a radiomics nomogram based on magnetic resonance imaging (MRI) of the lumbar spine to detect MRD after MM treatment. METHODS: A total of 130 MM patients (55 MRD negative and 75 MRD positive) who had undergone MRD testing through next-generation flow cytometry were divided into a training set (n = 90) and a test set (n = 40). Radiomics features were extracted from lumbar spinal MRI (T1-weighted images and fat-suppressed T2-weighted images) by means of the minimum redundancy maximum relevance method and the least absolute shrinkage and selection operator algorithm. A radiomics signature model was constructed. A clinical model was established using demographic features. A radiomics nomogram incorporating the radiomics signature and independent clinical factor was developed using multivariate logistic regression analysis. RESULTS: Sixteen features were used to establish the radiomics signature. The radiomics nomogram included the radiomics signature and the independent clinical factor (free light chain ratio) and showed good performance in detecting the MRD status (area under the curve: 0.980 in the training set and 0.903 in the test set). CONCLUSIONS: The lumbar MRI-based radiomics nomogram showed good performance in detecting MRD status in MM patients after treatment, and it is helpful for clinical decision-making. KEY POINTS: • The presence or absence of minimal residual disease status has a strong predictive significance for the prognosis of patients with multiple myeloma. • A radiomics nomogram based on lumbar MRI is a potential and reliable tool for evaluating minimal residual disease status in MM.

Clinicopathologic characteristics and prognostic of gastric cancer in young patients.

OBJECTIVES: Gastric cancer (GC) in young patients is thought to exhibit a worse prognosis due to specific clinicopathologic characteristics and delayed diagnosis; however, the data are controversial. This study aimed to analyse the clinicopathologic characteristics and prognostic factors of GC in young patients and to determine whether GC is a different clinical entity in younger vs. older patients. PATIENTS AND METHODS: Clinical data of 3930 gastric cancer patients who underwent radical gastrectomy were retrospectively analysed and divided into two age groups. The younger group consisted of 342 cases of patients aged 40 years or younger at the time of surgery, and the older group included 3588 cases of patients older than 40 years. Clinicopathologic characteristics were compared using Pearson's χ(2) or Fisher's exact tests, and survival curves were constructed using the Kaplan-Meier method. RESULTS: Clinicopathologic characteristics of the younger group exhibited a predominance of females (p < 0.001), diffuse stomach lesions (p = 0.014), signet-ring cell type (p < 0.001), poorly differentiated histological tumours (p < 0.001), Borrmann type IV (p < 0.001), mixed Lauren's classification types (p = 0.004), and recurrence rate in the gastric remnant (p < 0.001). The overall 5-year survival rates in the younger group and older group were 60.8% and 53.7%, respectively (p = 0.017). When stratified by TNM stage, the younger group exhibited enhanced 5-year survival at stage IV compared with the older group (26.9% VS. 10.3%, p = 0.003). CONCLUSION: Although younger patients with GC exhibit more aggressive cancer patterns and higher recurrence rate in the gastric remnant, the overall 5-year survival rate may be better than older patients.

Quercetin inhibits breast cancer cell proliferation and survival by targeting Akt/mTOR/PTEN signaling pathway.

Recently, natural compounds such as quercetin have gained an increasing amount of attention in treating breast cancer. However, the exact mechanisms responsible for the antiproliferative functions of quercetin are not completely understood. Therefore, we aimed to examine quercetin impacts on breast cancer cell proliferation and survival and the involvement of PI3K/Akt/mTOR pathway. Breast cancer MDA-MB-231 and MCF-7 cells were exposed to quercetin, and cell proliferation was assessed by MTT assay. ELISA was applied to evaluate cell apoptosis. The expression levels of apoptotic mediators such as caspase-3, Bcl-2, Bax and PI3K, Akt, mTOR, and PTEN were assessed via qRT-PCR and western blot. We found that quercetin suppressed dose dependently cell growth capacity in MDA-MB-231 and MCF-7 cells. In addition, quercetin treatment increase apoptosis in both cells lines via modulating the pro- and antiapoptotic markers. Quercetin upregulated PTEN and downregulated PI3K, Akt, and mTOR, hence suppressing this signaling pathway in cells. In conclusion, we showed antiproliferative and pro-apoptotic function of quercetin in breast cancer cell lines, which is mediated by targeting and suppressing PI3K/Akt/mTOR signal transduction.

Significant influence of urban human activities and marine input on rainwater chemistry in a coastal large city, China.

The coastal urban region is generally considered an atmospheric receptor for terrestrial and marine input materials, and rainfall chemistry can trace the wet scavenging process of these materials. Fast urbanization in China's east coastal areas has greatly altered the rainwater chemistry. However, the chemical variations, determinants, and sources of rainfall are unclear. Therefore, the typical coastal city of Fuzhou was selected for 1-year rainwater sampling and inorganic ions were detected to explore above problems. The findings depicted that rainwater ions in Fuzhou were slightly different from those in other coastal cities. Although NO3-, SO42-, Ca2+ and NH4+ dominated the rainwater ions, the marine input Cl- (22 %) and Na+ (11 %) also contributed a considerable percentage to the rainwater ions. Large differences in ion concentrations (2∼28 times) were found in monthly scale due to the rainfall amount. Both natural and anthropogenic determinants influenced the rainwater ions in coastal cities, such as SO2 emission, air SO2 and PM10 content on rainwater SO42-, NO3-, and Ca2+, and soot & dust emission on rainwater SO42-, NO3-, indicating the vital contribution of human activities. Stoichiometry and positive matrix factorization-based sources identification indicated that atmospheric dust/particles were the primary contributor of Ca2+ (83.3 %) and F- (83.7 %), and considerable contributor of SO42- (39.5 %), NO3- (38.3 %) and K+ (41.5 %). Anthropogenic origins, such as urban waste volatilization and fuel combustion emission, contributed 95 % of NH4+, 54.5 % of NO3- and 41.9 % of SO42-, and the traffic sources contribution was relatively higher than fixed emission sources. The marine input represented the vital source of Cl- (77.7 %), Na+ (84.9 %), and Mg2+ (55.3 %). This work highlights the significant influence of urban human activities and marine input on rainwater chemicals and provides new insight into the material cycle between the atmosphere and earth-surface in coastal city.

[Value of combined detection of urinary Livin and Survivin mRNA expression in the early diagnosis of bladder cancer].

OBJECTIVE: To evaluate the value of urine Livin and Survivin mRNA expression in the early diagnosis of bladder cancer. METHODS: Fifty-two cases of early bladder cancer and 30 cases of non-urinary system tumors were selected for the combined detection of urinary Livin and Survivin and urine cytology. RESULTS: Livin and Survivin in urine and urinary cytology sensitivity were 71.2% (37/52) , 67.3% (35/52), 23.1% (12/52); Specificity were 96.7% (29/30) , 93.3% (28/30) and 96.7% (29/30) respectively. Urine Survivin sensitivity, specificity compared with Livin were no significant difference (all P > 0.05). Urinary Livin and Survivin were more sensitive than urine cytology, and the differences were statistically significant(all P < 0.05). CONCLUSION: The combined urinary detection of Livin, Survivin mRNA expression is a noninvasive early diagnosis of bladder cancer with sensitivity and specificity.

When does cognitive crafting matter more in enhancing employee thriving at work? The moderating role of skill variety and job autonomy.

The job crafting literature has not devoted much attention to the effects of specific forms of job crafting, particularly cognitive crafting. The present study builds on Conservation of Resources theory to explain how cognitive crafting might influence work meaningfulness for employees, and in turn, increase their experienced thriving at work. Moreover, we hypothesise that the impact of cognitive crafting on these outcomes is influenced by two motivational job characteristics: skill variety and job autonomy. To test our hypotheses, we collected three-wave survey data from 223 employees employed in a variety of occupations and industries in China. Results indicate that engaging in cognitive crafting enhances employees' work meaningfulness, resulting in thriving at work. Furthermore, skill variety and job autonomy are crucial moderators of these relationships. Specifically, when employees perceived low levels of skill variety or job autonomy, engaging in cognitive crafting was more likely to lead to enhanced work meaningfulness, which in turn resulted in higher levels of thriving at work. Implications for research, theory and practice are discussed.

Efficacy and safety of tart cherry supplementary citrate mixture on gout patients: a prospective, randomized, controlled study.

BACKGROUND: Low urine pH, which may be mediated by metabolic syndrome (MetS), is common in gout. Tart cherries are shown to improve MetS symptoms and possess anti-inflammatory properties. However, the efficacy of tart cherry supplements on urine pH has yet to be studied. OBJECTIVES: This study aimed to investigate the efficacy and safety of tart cherry supplementary citrate (TaCCi) mixture on urine pH, serum urate (sUA), C-reactive protein (CRP), and gout flares in gout patients initiating urate-lowering therapy (ULT), in comparison to citrate mixture and sodium bicarbonate. METHODS: A prospective, randomized (1:1:1), open-label, parallel-controlled trial was conducted among 282 men with gout and fasting urine pH ≤ 6, who were initiating ULT with febuxostat (initially 20 mg daily, escalating to 40 mg daily if serum urate ≥ 360 µmol/L). Participants were randomized to groups taking either sodium bicarbonate, citrate mixture, or TaCCi mixture. All participants were followed every 4 weeks until week 12. Urine pH and sUA were co-primary outcomes, with various biochemical and clinical secondary endpoints. RESULTS: Urine pH increased to a similar extent in all three groups. SUA levels declined in all three groups as well, with no significant differences observed between the groups. At week 12, the TaCCi mixture group exhibited a greater reduction in the urine albumin/creatinine ratio (UACR) compared to the other two groups (p < 0.05). Participants taking TaCCi mixture or citrate mixture experienced fewer gout flares than those in the sodium bicarbonate group over the study period (p < 0.05). Additionally, the TaCCi mixture group had a lower CRP level at week 12 relative to the other two groups (p < 0.01). Adverse events were similar across all three groups. CONCLUSION: The TaCCi mixture had similar efficacy and safety on urine alkalization and sUA-lowering as the citrate mixture and sodium bicarbonate in patients with gout. However, the TaCCi mixture resulted in greater improvements in UACR and CRP, which suggests that tart cherry supplements may provide additional benefits for renal protection and reduce inflammation in gout, particularly when starting ULT. TRIAL REGISTRATION: This project was registered in ChiCTR ( www.chictr.org.cn ), with the registration number: ChiCTR2100050749.

Proteomic characterization and evolutionary analyses of zona pellucida domain-containing proteins in the egg coat of the cephalochordate, Branchiostoma belcheri.

BACKGROUND: Zona pellucida domain-containing proteins (ZP proteins) have been identified as the principle constituents of the egg coat (EC) of diverse metazoan taxa, including jawed vertebrates, urochordates and molluscs that span hundreds of millions of years of evolutionary divergence. Although ZP proteins generally contain the zona pellucida (ZP) structural modules to fulfill sperm recognition and EC polymerization functions during fertilization, the primary sequences of the ZP proteins from the above-mentioned animal classes are drastically different, which makes it difficult to assess the evolutionary relationships of ZP proteins. To understand the origin of vertebrate ZP proteins, we characterized the egg coat components of Branchiostoma belcheri, an invertebrate species that belongs to the chordate subphylum Cephalochordata. RESULTS: Five ZP proteins (BbZP1-5) were identified by mass spectrometry analyses using the egg coat extracts from both unfertilized and fertilized eggs. In addition to the C-terminal ZP module in each of the BbZPs, the majority contain a low-density lipoprotein receptor domain and a von Willebrand factor type A (vWFA) domain, but none possess an EGF-like domain that is frequently observed in the ZP proteins of urochordates. Fluorescence in situ hybridization and immuno-histochemical analyses of B. belcheri ovaries showed that the five BbZPs are synthesized predominantly in developing eggs and deposited around the extracellular space of the egg, which indicates that they are bona fide egg coat ZP proteins. BbZP1, BbZP3 and BbZP4 are significantly more abundant than BbZP2 and BbZP5 in terms of gene expression levels and the amount of mature proteins present on the egg coats. The major ZP proteins showed high polymorphism because multiple variants are present with different molecular weights. Sequence comparison and phylogenetic analysis between the ZP proteins from cephalochordates, urochordates and vertebrates showed that BbZP1-5 form a monophyletic group and share no significant sequence similarities with the ZP proteins of urochordates and the ZP3 subtype of jawed vertebrates. By contrast, small regions of homology were identifiable between the BbZP and ZP proteins of the non-jawed vertebrate, the sea lamprey Petromyzon marinus. The lamprey ZP proteins were highly similar to the ZP1 and ZP2 subtypes of the jawed vertebrates, which suggests that the ZP proteins of basal chordates most likely shared a recent common ancestor with vertebrate ZP1/2 subtypes and lamprey ZP proteins. CONCLUSIONS: The results document the spectra of zona pellucida domain-containing proteins of the egg coat of basal chordates. Particularly, the study provides solid evidence for an invertebrate origin of vertebrate ZP proteins and indicates that there are diverse domain architectures in ZP proteins of various metazoan groups.

Microstructure and Constitutive Equation of Hot Compressive Fe-15Mn-15Al-5Ni-1C Low-Density Steel.

The hot deformation behavior and dynamic recrystallization (DRX) of Fe-15Mn-15Al-5Ni-1C low-density steel in the as-cast state was investigated via hot compression experiments over temperature and strain rate ranges of 925 to 1150 °C and 0.01 to 10 s-1, respectively. A constitutive equation and a critical DRX model of the Fe-15Mn-15Al-5Ni-1C low-density steel were also constructed. The results showed that higher strain rates resulted in significant work hardening and subsequent rapid softening of the Fe-15Mn-15Al-5Ni-1C low-density steel, while lower strain rates resulted in predominantly steady-state flow behavior. The activation energy of deformation for the Fe-15Mn-15Al-5Ni-1C low-density steel was Q = 540 kJ mol-1 and the stress index was n = 4. The hot deformation mechanism was solute dragging and dislocation climbing, which was controlled by the strain rate. Increasing the deformation temperature or strain rate reduced the critical stress value σc of the DRX of the Fe-15Mn-15Al-5Ni-1C low-density steel and contributed to the DRX of austenite and δ-ferrite. The Fe-15Mn-15Al-5Ni-1C low-density steel after the hot compression deformation was mainly composed of austenite, ferrite, and κ carbide phases.

New insight into the response and transport of nitrate in karst groundwater to rainfall events.

Although numerous studies focused on nitrate source, transformation and transport of river water in karst area have been reported, it's still unclear in understanding nitrate main source and transformation in karst groundwater system and how nitrate transport from soil to water during rainfall events in karst critical zone. In order to explore the response and transport of nitrate in karst groundwater to rainfall events, different depths of well water before, during and after rainfall event were sampled, and hillslope runoff, surface runoff of different land-use types during rainfall event were sampled synchronously at a typical karst agricultural catchment in Southwest China. Results showed that fluctuations of EC, pH and DO in deep borehole well (W1) and artesian well (W2) were small, on the contrary, variations of EC and DO in shallow well (W3) were large during sampling period. The nitrate concentrations and isotopic values indicated that nitrate in karst groundwater mainly originated from chemical fertilizer (CF), and influenced by denitrification process. High intensity of denitrification was observed in deep groundwater (87%) and artesian well water (almost 100%). Extremely high dual nitrate isotope values up to 46.8 ± 1.5‰ and 24.7 ± 0.5‰ were found in the deep artesian well. The small variation of water chemistry (EC, DO and pH), nitrate concentration and dual nitrate isotope values in deep wells during sampling period suggested that newly supplied nitrogen in deep groundwater during rainfall events also comes from deep groundwater. Low nitrogen concentrations in hillslope subsurface flow and surface runoff suggests that nitrogen transport process leading to increase of water nitrogen content mainly occur in depression. Nitrogen in depression soil is mainly transported to groundwater through fissures, fractures and conduits, rather than through vertical migration processes in the soil during rainfall events.

Seroprevalence of Toxoplasma gondii infection in women with a gynecological tumor living in eastern China.

The association between Toxoplasma gondii (T. gondii) infection and malignancy has attracted increased attention in recent years, but little is known of T. gondii infection among women diagnosed with a gynecological tumor (GT) in China. We conducted a case-control study involving 460 women diagnosed with a GT and 460 age-matched healthy controls (HCs) to estimate the infection process of T. gondii and understand the risk factors of T. gondii infection in patients with a GT. Levels of anti-T. gondii IgG and IgM were measured by enzyme-linked immunoassays every 12 months. After a median follow-up time of 4.3 years (range 4 to 5 years), 55/460 (11.96%) patients with a GT and 15/460 (3.26%) HCs were seroprevalence for T. gondii antibodies, respectively (P = 0.001). IgG antibodies against T. gondii were found in 54 GT patients (11.74%) and 15 HCs (3.26%), respectively (P = 0.001). The seroprevalence of T. gondii IgM antibodies was similar in patients with a GT and with HCs (2.83% vs 1.3%, P = 0.105). Multivariate stepwise logistic regression analysis revealed contact with cats (OR, 6.67; 95% CI [2.89-10.75]; P = 0.001), exposure to soil (OR, 2.16; 95% CI [1.14-4.10]; P = 0.019), being a farm-worker (OR, 4.17; 95% CI [1.20-11.49]; P = 0.006) and history of chemotherapy (OR, 3.16; 95% CI [1.56-6.45]; P = 0.001) to be independent risk factors for T. gondii infection. Women with an ovarian cancer or endometrial cancer had higher T. gondii seroprevalence than that of HCs. Moreover, T. gondii infection in patients with a GT mostly acquired within two years of diagnosis, but the infection in healthy controls had no obvious time characteristics. Here, we demonstrated that T. gondii infection is significantly higher in patients with a GT (especially in women with an ovarian tumor) compared to HCs. Thus, infection with this parasite should be avoided in patients with a GT, and the causal relationship between T. gondii and GTs should be studied in detail.

Fruit quality prediction based on soil mineral element content in peach orchard.

Mineral nutrition of orchard soil is critical for the growth of fruit trees and improvement of fruit quality. In the present study, the effects of soil mineral nutrients on peach fruit quality were studied by using artificial neural network model. The results showed that the four established ANN models had the highest prediction accuracy (R 2 = .9735, .9607, .9036, and .9440, respectively). The results of prediction model sensitivity analysis showed that available B, Ca, N, and K in the soil had the greatest influence on the single fruit weight, available Fe, K, B, and Ca in the soil had the greatest effect on fruit soluble solid content, available Ca, N, B, and K in the soil had the greatest influence on the fruit titratable acid content, and available Ca, Fe, N, and Mn in the soil had the greatest effect on fruit edible rate. The response surface methodology analysis determined the optimal range of these mineral elements, which is critical for guiding precision fertilization in peach orchards and improving peach fruit quality.

Constitutive Equation and Hot Processing Map of Mg-16Al Magnesium Alloy Bars.

A Gleeble-2000D thermal simulation machine was used to investigate the high-temperature hot compression deformation of an extruded Mg-16Al magnesium alloy under various strain rates (0.0001-0.1 s-1) and temperatures (523-673 K). Combined with the strain compensation Arrhenius equation and the Zener-Hollomon (Z) parameter, the constitutive equation of the alloy was constructed. The average deformation activation energy, Q, was 144 KJ/mol, and the strain hardening index (n ≈ 3) under different strain variables indicated that the thermal deformation mechanism was controlled by dislocation slip. The Mg-16Al alloy predicted by the Sellars model was characterized by a small dynamic recrystallization (DRX) critical strain, indicating that Mg17Al12 particles precipitated during the compression deformation promoted the nucleation of DRX. Hot processing maps of the alloy were established based on the dynamic material model. These maps indicated that the high Al content, precipitation of numerous Mg17Al12 phases, and generation of microcracks at low temperature and low strain rate led to an unstable flow of the alloy. The range of suitable hot working parameters of the experimental alloy was relatively small, i.e., the temperature range was 633-673 K, and the strain rate range was 0.001-0.1 s-1.

Rainfall and conduit drainage combine to accelerate nitrate loss from a karst agroecosystem: Insights from stable isotope tracing and high-frequency nitrate sensing.

Understanding where nitrate is mobilized from and under what conditions is required to reduce nitrate loss and protect water quality. Low frequency sampling may inadequately capture hydrological and biogeochemical processes that will influence nitrate behavior. We used high-frequency isotope sampling and in-situ nitrate sensing to explore nitrate export and transformation in a karst critical zone. Nitrate was mobilised during light rainfall, and transferred from soil layers to the karst matrix, where some nitrate was retained and denitrified. Nitrate isotopic composition changed rapidly during the rising limb of events and slowly during the falling limb. The main nitrate source was synthetic fertiliser (up to 80% during event flow), transported by conduit flow following high rainfall events, and this contribution increased significantly as discharge increased. Soil organic nitrogen contribution remained constant indicating at baseflow this is the primary source. Isotope source appointment of nitrate export revealed that synthetic fertilizer accounted for more than half of the total nitrate export, which is double that of the secondary source (soil organic nitrogen), providing valuable information to inform catchment management to reduce nitrate losses and fluvial loading. Careful land management and fertilizer use are necessary to avoid nitrate pollution in the karst agroecosystem, for example by timing fertilizer applications to allow for plant uptake of nitrate before rainfall can flush it from the soils into the karst and ultimately into catchment drainage.

Determining rainwater chemistry to reveal alkaline rain trend in Southwest China: Evidence from a frequent-rainy karst area with extensive agricultural production.

Rainwater chemistry plays an important role in the earth-surficial ecosystem, but studies on rainwater chemical composition of karst agro-ecosystem are rare. To explore the rainwater alkalization and the provenance of components responsible for neutralization, two-years chemical monitoring of rainwater was carried out in a karst agricultural catchment in Southwest China. The main findings suggest that SO42-, NO3-, Ca2+, and NH4+ are the principal ions. All the ionic contents show distinctly seasonal variation (highest in winter) in response to variations in seasonal precipitation because the rain-scour process can efficiently remove atmospheric materials. Source identification indicates that Cl- and Na+ are mainly derived from marine input whereas SO42- and NO3- are controlled by anthropogenic emission, in particular, fixed emission sources. The source of NH4+ is attributed to intense agricultural production, while Ca2+ and Mg2+ are mainly derived from calcite dissolution. The rainwater alkalization caused by the seasonal acid neutralization (via basic components, Ca2+ and NH4+) is beneficial to crop growth but also reflect agricultural overfertilization. Sulfur controlled the total wet acid deposition (68%-94%) and could be a potential agent of weathering.

Increased Risk of Toxoplasma gondii Infection in Patients with Colorectal Cancer in Eastern China: Seroprevalence, Risk Factors, and a Case-Control Study.

The aim of this study was to explore the epidemiology of Toxoplasma gondii infection in patients with colorectal cancer (CRC) in eastern China. Therefore, 287 primary CRC patients and 287 age-matched healthy control subjects were recruited to estimate the seroprevalence of T. gondii and identify the risk factors of infection. Enzyme-linked immunoassays were used to test for anti-T. gondii immunoglobulin G (IgG) and IgM antibodies. Forty-six (16%) samples were positive for anti-T. gondii IgG antibodies in patients with CRC, compared with 26 (9.1%) in the healthy controls, a significant difference (P = 0.007). By contrast, eight (2.8%) patients tested positive for T. gondii IgM antibodies, compared with three (1.1%) in the controls, a difference that was not significant (P = 0.13). Multivariable backward stepwise logistic regression analysis revealed that a rural residence (OR 2.83; 95% CI 1.15-7.01; P = 0.024) and treatment with chemotherapy (OR 2.16; 95% CI 1.02-4.57; P = 0.045) were risk factors for T. gondii infection in patients with CRC. Thus, T. gondii infection is serious in patients with CRC, and a rural residence and treatment with chemotherapy are independent risk factors for infection by this parasite. Therefore, medical professionals should be aware of this pathogen in patients with CRC, and the causes of T. gondii infection in these patients need to be explored further.

High-frequency monitoring reveals how hydrochemistry and dissolved carbon respond to rainstorms at a karstic critical zone, Southwestern China.

Hydrochemical behavior and dissolved carbon dynamics are highly-sensitive to hydrological variations in the monsoon-influenced karstic critical zone which has high chemical weathering rates and experiences strong anthropogenic impact. Continuous high-frequency monitoring in the spring outlet of a karstic catchment in Southwestern China revealed that most hydrochemical variables changed distinctively in response to hydrologic variations, influenced by mixing of different sources and miscellaneous biogeochemical processes. Na+, K+ and SO42- varied significantly with hydrology, showing weak chemostatic behavior controlled by dilution. The flushing effect and random behavior of NO3- and Cl- likely reflect agricultural inputs from high throughflow. Soil CO2 in infiltrated water supports carbonate weathering, enabling DIC (dissolved inorganic carbon) and weathering products (e.g., Ca2+ and Mg2+) to maintain chemostatic behavior. Biogenic DIC exhibited a stronger chemostatic response than carbonate sources and was the foremost control in DIC behavior. Carbon exchange between DIC and DOC (dissolved organic carbon) did not significantly influence DIC concentration and δ13C due to very low DOC concentration. More DOC was exported by flushing from increasing discharge. Hysteretic analysis indicated that the transport processes were controlled by proximal sources mixing and diverse mobilization in various periods responding to rainstorms. NO3- and Cl- presented different hysteresis behavior as sourced from agricultural activities. DOC increased on the hydrograph rising limb and was controlled by a transport-limited regime. However, the hysteresis behavior of most weathering products and DIC were regulated by a process-limited regime in the karstic critical zone. Overall, biogeochemical processes, hydrogeological properties, storm intensity/magnitude and the timing of storms (antecedent conditions) are main factors influencing the response of hydrochemical variables and dissolved carbon to storm events.