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The Ocean University of China radiocarbon Accelerator Mass Spectrometry center (OUC-CAMS) provides routine 14C analyses on bulk organic matter, black carbon, plant fragments, particulate organic matter and lipid biomarkers. The OUC-CAMS also provides reliable δ13C measurements simultaneously with 14C measurements. We report the standard operation procedures of sample pretreatments, process blank results and data quality of 14C analyses for over 2.5 years before 2022. We also report a comparison of δ13C results between standalone and simultaneously with 14C measurements. [ABSTRACT FROM AUTHOR]

As one of the 5G waveform candidates, generalised frequency division multiplexing (GFDM) systems have been proposed to achieve lower out of band radiation and stronger robustness against synchronisation errors. However, theoretical BER performances of GFDM systems with in‐phase/quadrature (IQ) imbalance, as well as compensation strategies, have not been widely investigated. In this Letter, the authors evaluate theoretical BER performances of GFDM systems with transmitter IQ imbalance (IQI) before and after a proposed compensation method. Basically, they give approximated BER expressions for different modulations through considering introduced IQI completely as useless interference, and then derive a more precise BER expression for QPSK modulation. Additionally, they put forward a compensation method to remove IQI interference in GFDM systems at the cost of enlarged noise. Furthermore, analytical BER expressions with IQI compensation are derived, and then the effectiveness of the proposed compensation strategy is proven by theoretical and simulation results. [ABSTRACT FROM AUTHOR]

Glucose oxidase (GOD, EC.1.1.3.4) specifically catalyzes the reaction of β-d-glucose to gluconic acid and hydrogen peroxide in the presence of oxygen, which has become widely used in the food industry, gluconic acid production and the feed industry. However, the poor thermostability of the current commercial GOD is a key limiting factor preventing its widespread application. In the present study, amino acids closely related to the thermostability of glucose oxidase from Penicillium notatum were predicted with a computer-aided molecular simulation analysis, and mutant libraries were established following a saturation mutagenesis strategy. Two mutants with significantly improved thermostabilities, S100A and D408W, were subsequently obtained. Their protein denaturing temperatures were enhanced by about 4.4 °C and 1.2 °C, respectively, compared with the wild-type enzyme. Treated at 55 °C for 3 h, the residual activities of the mutants were greater than 72%, while that of the wild-type enzyme was only 20%. The half-lives of S100A and D408W were 5.13- and 4.41-fold greater, respectively, than that of the wild-type enzyme at the same temperature. This work provides novel and efficient approaches for enhancing the thermostability of GOD by reducing the protein free unfolding energy or increasing the interaction of amino acids with the coenzyme. [ABSTRACT FROM AUTHOR]

Sedimentary denitrification accounts for more than half of the global marine fixed nitrogen loss, but this removal is often restricted by nitrate diffusive supply in sediments. The results of this study showed that foraminiferal nitrate transport may supply nitrate below the nitrate penetration depth and promote nitrogen removal in sediments in contact with oxic overlying water. Six dominant foraminiferal species in the Yellow Sea sediments accumulated high concentrations of intracellular nitrate (25–68 mM), which is 1000 times higher than the maximum pore water nitrate concentration. Notably, this is the first time that Protelphidium tuberculatum, the most dominant species at almost all stations, is reported to have elevated intracellular nitrate. P. tuberculatum contributes 45% to 92% of the foraminiferal intracellular nitrate pools and plays an important role in foraminiferal nitrate transport. The potential foraminiferal denitrification rates below the nitrate penetration depth induced by foraminiferal nitrate transport ranged from 4 to 117 μmol N m−2 d−1 and contributed 3% to 81% of sedimentary denitrification. The intensity of foraminiferal nitrate transport showed a negative correlation with the nitrate penetration depth and positively correlated with the chlorophyll a (Chl a) and chloroplastic pigment equivalent concentrations, which indicate that shallower redox depth (nitrate penetration depth) and increased food supply (Chl a, chloroplastic pigment equivalent) may promote foraminiferal nitrate transport. The trophic oxygen model was modified by adding the pore water nitrate to explain foraminiferal nitrate transport in various marine environments, and this modified trophic oxygen model predicts the observed high foraminiferal nitrate transport intensity. [ABSTRACT FROM AUTHOR]

The Ocean University of China radiocarbon accelerator mass spectrometer center (OUC-CAMS) is equipped with a mini carbon dating system (MICADAS) from the Ionplus AG. The MICADAS allows measurements of both graphite and CO 2 samples because of the design of a hybrid ion source. Also, both 13C and 14C of organic samples can be measured at the same time because a stand-alone IRMS is coupled to the MICADAS. The OUC-CAMS provides routine 14C analyses on bulk organic carbon of various types, such as sediments, particulate matter, plant fragments, and compound-specific lipid biomarkers. Here we report the performance based on continuous analysis of international reference materials of 195 graphite data and 605 gas data carried out over the 2.5 years before 2022. [ABSTRACT FROM AUTHOR]

Multistep physical and biological processing of organic matter in marginal seas modifies its composition, sedimentary pathway, and burial efficiency. This study examines how organic geochemical signals pertaining to the source and transformation in surface sediments are transported and preserved in the conduit portion of source-to-sink sedimentary systems in marginal seas such as the Taiwan Strait (TS). The aim is to gain more insight in not only the total OC burial in this highly dynamic region, but also to establish a quantitative assessment of the provenance and age of this carbon. Our study revealed that terrestrial plant wax n -alkanols represent a portion of terrestrial organic matter, characterized by refractory property and strong mobility leading to efficient transfer from the river mouth to the shelf. Soil bacteria-derived branched glycerol dialkyl glycerol tetraethers (br-GDGTs) represent the portion of terrestrial OM characterized by labile properties and low transmissibility restricted within the river mouth under normal conditions, except for episodic and pulse delivery situations. Sedimentary OC in the TS is typically characterized by a large amount of ancient OC with intensive oxidation, indicated by extremely old 14C ages (<13000 ± 180 yr) and lower petrogenic OC content in marine sediments than that of rocks sourced from the land. Diverse sourced OC supply and accumulation patterns in shallow marine conduit systems mainly influenced by complex physical processes. Quantitative source apportionment of sedimentary OC using a ternary mixing model based on the bulk δ13C and Δ14C proxies combined with sediment mass accumulation rates revealed 0.01–3.44, 0.002–3.79, and 0–3.38 mg C cm−2 yr−1 of marine, terrestrial biospheric, and petrogenic OC burial loadings in the TS. Marine OC burial could only explain 30% of net air–sea CO 2 sequestration in a narrow conduit system such as the TS, which is characterized by high sediment resuspension and strong hydrodynamic processes due to strong tidal currents and wind-driven circulation. Our findings revealed the net C buried in different marginal seas varies as a function of local couplings between physical processes and biogeochemical characteristics. [ABSTRACT FROM AUTHOR]

A long‐standing enigma in oceanography is why terrestrial organic matter is "missing" in the global ocean, despite the considerable discharge into it every year. Although some explanations, such as mineralogical composition, hydrodynamic processes, and priming effect, have been proposed, we hypothesize that the essential mechanism behind the missing organic matter is microbial processing, for which the underlying coupled geochemical, molecular, and genetic evidence is unknown. An ultra‐large‐volume, long‐term river–seawater stratified simulation system was constructed to unravel the microbially driven fate of terrigenous particulate organic matter (POM) in oceans. Analysis of combining the molecular with POM chemical composition data suggests that Bacteroidetes could act as pioneers in the processing of terrigenous POM in oceans, degrading high‐molecular‐weight, high‐carbon compounds such as polysaccharides. Remaining low‐molecular‐weight nitrogenous organic matter is subsequently degraded by Planctomycetes and Proteobacteria. Isotopic signals show that this preferential degradation causes a distinct "aging" effect of POM, and along with nitrification enhanced by remineralization, causes a decrease in the POM C : N ratio. Degradation of terrigenous POM and bacterial biomass biosynthesis leads to positive deviations in δ15N and δ13C. Relatively refractory hydrocarbons, aromatic compounds, and phenols are accumulated by microbial processes in this system. This study provides mechanistic insights into the missing chemical and isotopic signals and microbially driven fate of terrigenous POM in the ocean, with important implications for how riverine material input affects marine carbon and nitrogen cycling. [ABSTRACT FROM AUTHOR]

One of the key challenges in understanding the role of hadal trenches in the marine organic carbon (OC) cycle is the need to distinguish OC sources, assess accumulation rates, and identify controlling processes. To address this, sediment core samples from the southern Mariana Trench were analyzed for their contents and carbon isotopes (13C and 14C) of both total OC (TOC) and saturated long-chain fatty acid (n -LCFA). Our findings indicate that sedimentary OC in the southern Mariana Trench is primarily derived from marine sources, as indicated by TOC-δ13C values ranging from −19.9‰ to −17.0‰ and the ratios of TOC to total nitrogen (TOC/TN) of 5.5–8.4. The 14C ages of TOC and n -LCFA ranged from 7159 to 22,662 yr and 8713 to 22,819 yr, respectively, with both showing gradual down-core increasing trends. This allows for a conservative estimation of sedimentation rate of 17.5–18.7 cm kyr−1 in the southern Mariana Trench, leading to a sedimentary OC accumulation rate of 529–942 g C m−2 kyr−1, which is 1–2 orders of magnitude higher than that observed in the abyssal plain. We propose that the continuous lateral downslope transport played a significant role in focusing pre-aged OC into the southern Mariana Trench. Therefore, hadal trenches are likely to accumulate substantial amounts of sedimentary OC in the deep ocean. • A gravity sediment core MT03 was collected from the southern Mariana Trench. • Contents and carbon isotopes (13C and 14C) of both TOC and n -LCFA were analyzed. • The sediment OC in core MT03 was primarily derived from marine sources. • Sedimentation rate of 17.5–18.7 cm kyr−1 estimated based on 14C ages of organics. • Pre-aged OC accumulated in the trench with a burial flux of 529–942 g C m−2 kyr−1. [ABSTRACT FROM AUTHOR]

Objective: To detect the expression level of the Mfn2 gene in hepatocellular carcinoma (HCC) and adjacent normal liver tissues and further analyze its anticancer effects.Methods: The expression levels of Mfn2, GLS1 and the autophagy-related proteins lc3b and Beclin1 in liver cancer and adjacent tissues in patients with liver cancer were detected by real-time-quantitative polymerase chain reaction (RT-qPCR). The HepG2 human HCC cell line was cultured in vitro, and the Mfn2 protein was stably expressed through transfection of a high Mfn2 expression plasmid. The Cell-Counting Kit-8 (CCK-8) method was used to observe the effect of Mfn2 overexpression on the activity of HepG2 cells. Furthermore, RT-qPCR and Western blotting were performed to detect the effects of Mfn2 overexpression on the protein expression of GLS1, Beclin1 and lc3b.Results: Compared with tissues adjacent to cancer tissues, the mRNA levels of Mfn2, GLS1, Beclin1 and lc3b in liver cancer tissues were lower. Compared with normal hepatocytes, the expression of Mfn2, Beclin1 and lc3b in HCC cells was decreased, but the expression of GLS1 was increased. Compared with the control group (NC) transfected with empty plasmid, Mfn2 overexpression led to significant time-dependent inhibition of HepG2 cell activity and GLS1 protein expression (P < .05). In addition, Mfn2 overexpression induced autophagy by triggering the expression of autophagy-related proteins Beclin-1 and lc3b in HCC cells (all P < .05). The effect of transfection with a high-dose Mfn2 plasmid was more obvious than that of transfection with a low-dose Mfn2 plasmid (all P < .05).Conclusions: The expression of Mfn2, GLS1, Beclin1 and lc3b in HCC was lower than in normal liver tissue. The expression of Mfn2, Beclin1 and lc3b in HCC cells was decreased, but the expression of GLS1 was increased. Overexpression of Mfn2 inhibited GLS1 gene expression by inhibiting the activity of HCC cells and promoted the expression of Beclin1 and lc3b to induce autophagy, thereby exerting an anticancer effect. Further research is needed to clarify the mechanism of Mfn2 activity. [ABSTRACT FROM AUTHOR]

Abstract: Background: Diabetes mellitus (DM) is widely considered to be associated with risk of pancreatic cancer (PaC), however, whether DM is a cause or a consequence of PaC is still controversial. We examined this association by conducting a detailed meta-analysis of cohort studies. Methods: Studies were identified by searching Medline and Embase through November 30, 2010. Summary relative risks (RRs) with their corresponding 95% confidence intervals (CIs) were calculated using a random-effects model. Results: A total of thirty-five cohort studies were included in this meta-analysis. DM was associated with an increased risk of PaC (the summary RRs=1.94; 95% CI, 1.66–2.27), with significant evidence of heterogeneity among these studies (p <0.001, I 2 =93.6%). Subgroup analyses revealed that the increased risk of PaC was independent of geographic locations, sex, study design, alcohol consumption, body mass index (BMI) and smoking status. In addition, the relative risk of PaC was correlated negatively with the duration of DM, with the highest risk of PaC found among patients diagnosed within less than 1year. There was no significant publication bias (p =0.136 for Egger’s regression asymmetry test). Conclusions: Findings from this meta-analysis strongly support that diabetes is associated with an increased risk of PaC in both males and females and that DM is both an early manifestation and an etiologic factor of pancreatic cancer. [Copyright &y& Elsevier]

The alterations of nitrogen sources and cycling within the Three Gorges Reservoir (TGR) and downstream the Changjiang were investigated to understand the impacts of the construction of the Three Gorges Dam (TGD) and anthropogenic inputs from the associated watershed. Water samples collected in October 2016 were analyzed for hydrologic parameters, nutrient concentrations, and stable isotopes of nitrate (NO 3 −), ammonium (NH 4 +) and particulate matter. Nitrate dual stable isotope values ranged from +5.8‰ to +7.1‰ and −1.9‰ to +0.4‰ for δ15N and δ18O, respectively. δ15N values in particulate nitrogen (PN) ranged from +0.5‰ to +8.5‰, with slightly lower values before the dam. δ15N-NH 4 + values ranged between +10.5‰ and +19.4‰, likely reflecting the presence of ammonium assimilation throughout the TGR. The contribution of different nitrogen sources was calculated using a Bayesian mixing model. These sources, including soil organic nitrogen, ammonium fertilizer, and sewage effluent, contributed to elevated DIN concentrations within the TGR (83.2 μM–178.5 μM). The construction of the dam has also likely induced changes in the river environment such as ammonium assimilation in the surface waters and nitrification and/or remineralization within the deep waters of the TGR. Overall, during this investigation period, the TGR acted as a sink of PN (retaining 29%), yet negligibly influenced levels of TDN with ~96.5% of TDN exported to the downstream Changjiang and estuary. It is important to understand the long-term impacts of the TGD on the ecological environment of the Changjiang. This study highlights the influence that anthropogenic nitrogen sources have on the natural biogeochemical cycling within the TGR, showing the urgent need to reduce anthropogenic nitrogen pollution. • Stable isotopes of nitrogen species within the Three Gorges Reservoir were studied. • 29% of particulate nitrogen was retained in the Three Gorges Reservoir. • About 96.5% of total dissolved nitrogen exported to the downstream Changjiang. • Ammonium assimilation, nitrification and remineralization existed in the reservoir. • Main nitrate sources were sewage effluent, ammonium fertilizer, and soil nitrogen. [ABSTRACT FROM AUTHOR]

Abstract: Lactobacillus β-galactosidases are mostly heterodimeric proteins, which are encoded by the two overlapping genes, lacL and lacM, and produced in recombinant prokaryotic systems for higher yield. This is the first report on the expression of a heterodimeric β-galactosidase from Lactobacillus crispatus B470 in Pichia pastoris. The overlapping consecutive genes, lacL and lacM, that shared 17 nucleotides were cloned from the genomic DNA of L. crispatus. A recombinant plasmid harboring both expression cassettes of lacL and lacM was constructed and transformed into P. pastoris GS115 competent cells. Two recombinant P. pastoris strains (GSLac01 and GSLac02) showed the highest β-galactosidase activities of 24.5 and 31.0U/ml in the culture supernatants, respectively. The recombinant β-galactosidase (LcLacLM) from GSLac02 was purified to electrphoretic homogeneity by ion-exchange chromatography and molecular sieve chromatography. Similar to most Lactobacillus β-galactosidases that operate at moderately thermophilic and weak acid to neutral conditions, LcLacLM showed optimal activity at 50°C and pH 5.5–6.5. It’s the first report on functional and secretory expression of LacLM-type β-galactosidase in eukaryotic system. This strategy might be applied to the expression of other overlapping genes. [Copyright &y& Elsevier]

Diabetes mellitus (DM) is widely considered to be associated with pancreatic cancer, however, whether DM is a cause or consequence of pancreatic cancer is controversial. In the present study, 1458 patients with pancreatic ductal adenocarcinoma (PDAC) and 1528 age-, sex- and sociodemographic variables-matched controls were recruited in two university-affiliated hospitals from 1st January 2000 to 31st December 2009. DM was defined as fasting blood glucose (FBG) level of 7.0mmol/L or greater. An unconditional multivariable logistic regression analysis was used to estimate adjusted odds ratios (AORs) and 95% confidence interval (CI). Compared with controls, a moderate increased risk of PDAC was observed among cases with long-standing diabetes (⩾2-year duration), with an AOR (95% CI) of 2.11 (1.51–2.94). Interestingly, a significant higher risk was observed among cases with new-onset DM (<2-year duration), with an AOR of 4.43 (3.44–5.72) compared to controls without DM. In addition, we found a synergistic interaction between cigarette smoking and DM on modifying the risk of pancreatic cancer development (AOR=6.17, 95% CI 3.82–9.94). Similarly, a synergistic interaction between new-onset DM and family history of pancreatic cancer was found for pancreatic cancer risk, with an AOR (95% CI) of 11.04 (2.51–48.53). This study suggested that DM could be both an early manifestation of pancreatic cancer and an aetiologic factor. Possible effect modification on DM by family history of pancreatic cancer and smoking status should be further explored in future aetiologic studies. [Copyright &y& Elsevier]

Spectrum sensing plays an essential role in the detection of unused spectrum whole in cognitive radio networks, including cooperative spectrum sensing (CSS) and independent spectrum sensing. In cognitive radio ad hoc networks (CRAHNs), CSS enhances the sensing performance of cognitive nodes by exploring the spectrum partial homogeneity and fully utilizing the knowledge of neighboring nodes, e.g., sensing results and topological information. However, CSS may also open a door for malicious nodes, i.e., spectrum sensing data falsification (SSDF) attackers, which report fake sensing results to deteriorate the performance of CSS. Generally, the performance of CSS has an inverse relationship with the fraction of SSDF attackers. On the contrary, independent spectrum sensing is robust to SSDF attacks. Therefore, it is desirable to choose a proper sensing strategy between independent sensing and collaborative sensing for CRAHNs coexisting with various fractions of SSDF attackers. In this paper, a novel algorithm called Spectrum Sensing Strategy Selection (4S) is proposed to select better sensing strategies either in a collaborative or in an independent manner. To derive the maximum a posteriori estimation of nodes' spectrum status, we investigated the graph cut-based CSS method, through which the topological information cost function and the sensing results cost function were constructed. Moreover, the reputation value was applied to evaluate the performance of CSS and independent sensing. The reputation threshold was theoretically analyzed to minimize the probability of choosing the sensing manner with worse performance. Simulations were carried out to verify the viability and the efficiency of the proposed algorithm. [ABSTRACT FROM AUTHOR]