Climatic and environmental changes in the northeastern Tibetan Plateau are controlled by the Asian summer monsoon (ASM) and the westerlies, two key circulation components of the global climate system ...which directly affect a large human population and associated ecosystems in eastern Asia. During the past few decades, a series of Holocene palaeoclimatic records have been obtained from sediment cores from Lake Qinghai and from various other geological archives in the surrounding area of the northeastern Tibetan Plateau. However, because of uncertainties regarding the sediment chronologies and the climatic significance of the proxies used, the nature of Holocene climatic changes in the region remains unclear and even controversial. Here we review all major classes of the published data from drilled cores from Lake Qinghai, as well as other evidence from lakes and aeolian deposits from surrounding areas, in order to reconstruct changes in moisture patterns and possible summer monsoon evolution in the area during the Holocene. Combining the results of moisture and precipitation proxies such as vegetation history, pollen-based precipitation reconstruction, aeolian activity, lake water depth/lake level changes, salinity and sediment redness, we conclude that moisture and precipitation began to increase in the early Holocene, reached their maximum during the middle Holocene, and decreased during the late Holocene - similar to the pattern of the East Asian summer monsoon (EASM) in northern China. It is clear that the region experienced a relatively dry climate and weak EASM during the early Holocene, as indicated by relatively low tree pollen percentages and fluctuating pollen concentrations; generally low lake levels of Lake Qinghai and the adjacent Lake Hurleg and Lake Toson in the Qaidam Basin; and widely distributed aeolian sand deposition in the Lake Qinghai Basin and the nearby Gonghe Basin to the south, and in the eastern Qaidam Basin to the west. We argue that the ostracod δ18O record, which is widely used as a proxy of effective moisture and summer monsoon intensity in lake sediments, at least in Lake Qinghai, and which exhibits light values in the early Holocene and heavier values thereafter, cannot be used to reflect the strength of the EASM or the intensity of monsoon precipitation - as is also the case for leaf wax δ2H records. Rather, we argue that as is the case of the Chinese speleothem δ18O record, which also is often interpreted as an EASM proxy, it reflects variation in the δ18O of precipitation. Overall, we suggest that the EASM significantly affected precipitation in the northeastern Tibetan Plateau during the Holocene; and that it increased in strength during the early Holocene, reached a maximum during the middle Holocene and decreased during the late Holocene.
•Lake Qinghai and the adjacent lakes were generally low and aeolian sands were widely distributed in the northeastern Tibetan Plateau during the early Holocene.•Ostracod δ18O records from Lake Qinghai cannot be used to reflect the strength of the East Asian summer monsoon or the intensity of monsoon precipitation.•Moisture and precipitation at Lake Qinghai and its environs began to increase in the early Holocene, reached their maximum during the middle Holocene, and decreased during the late Holocene.
Total concentration and chemical partitioning of heavy metals are commonly used in environmental quality assessment; however, their comparability and comprehensive application are far less discussed. ...Herein, bioavailability, pollution and eco-risk of As, Cd, Cr, Cu, Ni, Pb and Zn in surface sediments of Erhai Lake were evaluated referring to multiple indices following the experimental methods of complete digestion, optimized Community Bureau of Reference (BCR) and 1.0 M HCl extractions. Results of bioavailability for most metals were similar and comparable from BCR and HCl extractions. While bioavailable concentrations of Cd and Pb from HCl extraction were significantly (p < 0.01) lower than those from BCR extraction, indicating BCR extraction is more efficient. Results of enrichment factor (EF) and concentration enrichment ratio (CER) suggested that Cd was the highest polluted element followed by As, Pb and Zn, whereas Cr, Cu and Ni were mainly natural in origin. Similar concentrations of anthropogenic As from EF and CER assessments indicated anthropogenic As mainly existed in bioavailable form. However, anthropogenic Cd, Pb and Zn existed in both bioavailable and residue forms, resulting in the underestimation of anthropogenic metals by the CER assessment. The sediment quality guidelines (SQGs), potential ecological risk index (Er) and risk assessment code (RAC) showed inconsistent eco-risks for each of the metals except Cd. Combining pollution level and chemical partitioning with SQGs, Er and RAC assessments, high eco-risk of Cd, moderate eco-risk of As and Pb, and low eco-risk of Cr, Cu, Ni and Zn were graded. Our study highlights the limitation of single index and the necessity of integrating multiple indices following total concentration and chemical partitioning in metal pollution and eco-risk assessments.
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●Metal pollution and risk were studied by different chemical data and assessment indices.●The EF, CERBCR and CERHCl all indicated Cd, As, Pb and Zn were typical pollutants.●Anthropogenic Cd, Pb and Zn were underestimated by the CERBCR and CERHCl than by EF.●Only Cd displayed similar risk grading from the SQGs, Er and RAC assessments.●Metal pollution and risk assessments should integrate multiple chemical data and indices.
Bioavailability, pollution and eco-risk of heavy metals in lake sediment were explored using multiple indices following complete digestion, BCR and 1.0 M HCl extractions.
Nitrile hydratase (NHase) is an excellent biocatalyst for the synthesis of amide compounds and is composed of two heterologous subunits. However, the secretory expression of NHase has been difficult ...to achieve because of its complex expression mechanism. In this work, a novel fluorescent probe Rho‐IDA‐CoII was synthesized by a one‐pot method. Rho‐IDA‐CoII could specifically label His‐tagged proteins in vitro, such as for staining in‐gel, Western blot, and ELISA analysis. Furthermore, Rho‐IDA‐CoII combined with dot blots could quantitatively detect His‐tagged proteins at between 1–10 pmol and perform high‐throughput screening for the NHase signal peptide library. Recombinant Bacillus subtilis WB800/phoB‐HBA with the extracellular expression of NHase was screened (ca. 6500 clones). After optimization of fermentation conditions, the NHase activity in the culture supernatant reached 17.34±0.16 U/mL. This is the first time that secretory NHase has been expressed in B. subtilis successfully.
A novel fluorescent probe, Rho‐IDA‐CoII, which could be used to specifically label His‐tagged proteins in vitro, was synthesized by a one‐pot method. The recombinant that could secrete NHase HBA was screened from a signal peptide (SP) library (ca. 6500 clones) with Rho‐IDA‐CoII. This is the first time that secreted NHase has been expressed in Bacillus subtilis successfully.
Total chemical synthesis provides a unique approach for the access to uncontaminated, monodisperse, and more importantly, post-translationally modified membrane proteins. In the present study we ...report a practical procedure for expedient and cost-effective synthesis of small to medium-sized membrane proteins in multimilligram scale through the use of automated Fmoc chemistry. The key finding of our study is that after the attachment of a removable arginine-tagged backbone modification group, the membrane protein segments behave almost the same as ordinary water-soluble peptides in terms of Fmoc solid-phase synthesis, ligation, purification, and mass spectrometry characterization. The efficiency and practicality of the new method is demonstrated by the successful preparation of Ser64-phosphorylated M2 proton channel from influenza A virus and the membrane-embedded domain of an inward rectifier K+ channel protein Kir5.1. Functional characterizations of these chemically synthesized membrane proteins indicate that they provide useful and otherwise-difficult-to-access materials for biochemistry and biophysics studies.
Nitrile hydratase (NHase), an excellent bio-catalyst for the synthesis of amide compounds, was composed of two heterologous subunits. A thermoalkaliphilic NHase NHCTA1 (Tm = 71.3°C) obtained by in ...silico screening in our study exhibited high flexibility of α-subunit but excellent thermostability, as opposed to previous examples. To gain a deeper structural insight into the thermostability of NHCTA1, comparative molecular dynamics simulation of NHCTA1 and reported NHases was carried out. By comparison, we speculated that β-subunit played a key role in adjusting the flexibility of α-subunit and the different conformations of linker in "α5-helix-coil ring" supersecondary structure of β-subunit can affect the interaction between β-subunit and α-subunit. Mutant NHCTA1-α
C with a random coil linker and mutant NHCTA1-αβγ with a truncated linker were therefore constructed to understand the impact on NHCTA1 thermostability by varying the supersecondary structure. The varied thermostability of NHCTA1-α
C and NHCTA1-αβγ (Tm
= 74.4°C, Tm
= 65.6°C) verified that the flexibility of α-subunit adjusted by β-subunit was relevant to the stability of NHCTA1. This study gained an insight into the NNHCTA1 thermostability by virtual dynamics comparison and experimental studies without crystallization, and this approach could be applied to other industrial-important enzymes.
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•A systematic review identified 22 studies from 10 countries of the world.•Short-term exposure to NO2 was associated with an increased odds of depression.•Long-term PM2.5, PM10, and ...NO2 exposure was not associated with depression.•Short-term PM2.5, PM10, SO2, and O3 exposure was not associated with depression.
Although epidemiological studies have evaluated the associations of ambient air pollution with depression, the results remained mixed. To clarify the nature of the association, we performed a comprehensive systematic review and meta-analysis with the Inverse Variance Heterogeneity (IVhet) model to estimate the effect of ambient air pollution on depression. Three English and four Chinese databases were searched for epidemiologic studies investigating associations of ambient particulate (diameter ≤ 2.5 μm (PM2.5), ≤10 μm (PM10)) and gaseous (nitric oxide (NO), nitrogen dioxide (NO2), carbon monoxide (CO), sulfur dioxide (SO2) and ozone (O3)) air pollutants with depression. Odds ratios (OR) and corresponding 95% confidence intervals (CI) were calculated to evaluate the strength of the associations. We identified 22 eligible studies from 10 countries of the world. Under the IVhet model, per 10 µg/m3 increase in long-term exposure to PM2.5 (OR: 1.12, 95% CI: 0.97–1.29, I2: 51.6), PM10 (OR: 1.04, 95% CI: 0.88–1.25, I2: 85.7), and NO2 (OR: 1.05, 95% CI: 0.83–1.34, I2: 83.6), as well as short-term exposure to PM2.5 (OR: 1.01, 95% CI: 0.99–1.04, I2: 51.6), PM10 (OR: 1.01, 95% CI: 0.98–1.04, I2: 86.7), SO2 (OR: 1.03, 95% CI: 0.99–1.07, I2: 71.2), and O3 (OR: 1.01, 95% CI: 0.99–1.03, I2: 82.2) was not significantly associated with depression. However, we observed significant association between short-term NO2 exposure (per 10 µg/m3 increase) and depression (OR: 1.02, 95% CI: 1.00–1.04, I2: 65.4). However, the heterogeneity was high for all of the pooled estimates, which reduced credibility of the cumulative evidence. Additionally, publication bias was detected for six of eight meta-estimates. In conclusion, short-term exposure to NO2, but not other air pollutants, was significantly associated with depression. Given the limitations, a larger meta-analysis incorporating future well-designed longitudinal studies, and investigations into potential biologic mechanisms, will be necessary for a more definitive result.
Employing direct Z-scheme semiconductor heterostructures in photocatalysis offers efficient charge carrier separation and isolation of both redox reactions, thus beneficial to reduce CO2 into solar ...fuels. Here, a ZnS/ZnIn2S4 heterostructure, comprising cubic ZnS nanocrystals on hexagonal ZnIn2S4 (ZIS) nanosheets, is successfully fabricated in a single-pot hydrothermal approach. The composite ZnS/ZnIn2S4 exhibits microstrain at its interface with an electric field favorable for Z-scheme. At an optimum ratio of Zn:In (~ 1:0.5), an excellent photochemical quantum efficiency of around 0.8% is reached, nearly 200-fold boost compared with pristine ZnS. Electronic levels and band alignments are deduced from ultraviolet photoemission spectroscopy and UV-Vis. Evidence of the direct Z-scheme and carrier dynamics is verified by photo-reduction experiment, along with photoluminescence (PL) and time-resolved PL. Finally, diffuse-reflectance infrared Fourier transformed spectroscopy explores the CO2 and related intermediate species adsorbed on the catalyst during the photocatalytic reaction. This microstrain-induced direct Z-scheme approach opens a new pathway for developing next-generation photocatalysts for CO2 reduction.
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•We demonstrated that a facile single-pot hydrothermal method derived ZnIn2S4 decorated with ZnS as direct Z-scheme heterostructure.•This work covers the in-depth study of the Z-scheme mechanism and strain analysis.•We have provided more in-depth explanations of the origin and mechanism of Z-scheme process.•The DRIFTS study explores the reaction mechanism and the interaction of CO2 with catalyst during photocatalytic reaction.
D-Pantothenic acid (D-PA) is an essential vitamin with wide applications. However, the biotechnological production of D-PA is still not competitive with the chemical synthesis in terms of production ...cost. Ketopantoate hydroxymethyltransferase is a crucial enzyme in the D-PA synthetic pathway in Escherichia coli encoded by the panB gene. Here a hot spots study was applied to a ketopantoate hydroxymethyltransferase from Corynebacterium glutamicum (CgKPHMT) to relieve the product inhibitory effect and thus improve the D-PA production. Compared with the wild type, the double-site variant CgKPHMT-K25A/E189S showed 1.8 times higher enzyme activity and 2.1 times higher catalytic efficiency, 1.88 and 3.32 times higher inhibitory constant of α-ketoisovalerate and D-PA, respectively. The D-PA yield using E. coli W3110 adopted the double-site variant was 41.17 g·L−1 within 48 h, a 9.80 g·L−1 increase. Structural analysis of K25A/E189S revealed the expansion of the entry channel and the change of the electric charge from negative to uncharged due to the substitution from glutamic acid to serine at site 189. Our study emphasized the positive roles of ketopantoate hydroxymethyltransferase in D-PA production and paved the way by analyzing critical enzymes in the synthetic pathway of E. coli to increase the D-PA yield.
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•A double-site variant of KPHMT with improved properties was obtained by hot spot based-engineering.•The double-site variant K25A/E189S was increased by 2.8-fold and 2.1-fold to the wild-type in EA and Kcat.•The inhibitory effect of ketoisovalerate and D-PA on variant K25A/E189S was partially relieved.•The D-PA yield was increased by 9.80 g/L by mutagenesis of KPHMT in E. coli in a 5-L scale fermentation.
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•Zircon is good calibration standard for rutile dating with spot size of 44–90 µm.•Elemental fractionation between rutile and zircon was intensively investigated.•Two ages of rutile ...from the Dabie UHP rocks suggest different exhumation history.
Rutile U-Pb dating by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has received increasing attention in geological applications. Previous natural rutile reference materials are insufficient to meet the growing demand of working standards for laser U/Pb dating. In present study, we have developed a new calibration strategy for LA-ICP-MS rutile dating using the most popular zircon as reference material. The matrix-dependent elemental fractionation of rutile and zircon could effectively decrease to a better level by optimized analytical parameters and with large ablation spot size (44–90 µm). The acceptable Pb/U correction coefficient between rutile and zircon could be obtained while the diameter/depth ratio of the crater is above 1 after assessing elemental fractionation of different ablation size. Five rutile were analyzed by zircon calibration, and their ages show strong agreement with those obtained by secondary ion mass spectrometry (SIMS) or thermal ionization mass spectrometry (TIMS) analysis, with both precision and accuracy within ±2%. Two rutiles of eclogitic rocks from the Dabie orogen yield the ages of 207.0 ± 2.1 Ma and 205.6 ± 2.4 Ma, respectively. Both ages are conceivably younger than that previously reported rutile ages (218 Ma) for eclogites. The quite different U-Pb ages of rutile from different localities most likely indicate the different exhumation history of the subducted continental crust. LA-ICP-MS rutile U-Pb dating using zircon as an external calibration reference material would assuage rutile reference material insufficient supply and improve its widespread application.
This study presents investigations into the fabrication, characterization, and performance analysis of stretchable white random lasers based on 2D glutamine(GLN)‐functionalized WS2 quantum dots (QDs) ...enhanced by the integration of Au nanoparticles (NPs) and a wrinkled graphene structure. Wrinkled graphene holds the potential for achieving transient population inversion through electron collisions. Incorporating Au NPs introduces localized surface plasmon resonance (LSPR), which enhances the light‐matter interaction, resulting in reduced lasing thresholds. The GLN‐functionalized WS2 QDs exhibit strong photoluminescence emission, and their integration with a wrinkled graphene structure and Au NPs creates a synergistic effect that enhances the emission efficiency and enables the realization of white random lasing. The extensive characterization and analysis of the emission spectra under different deformation ratios provide valuable insights into the tunability and reliability of these devices, as well as the importance of light trapping due to the wrinkled graphene structure. The findings of this study underscore the significant potential of LSPR and wrinkled graphene structure induced stretchable and white random lasers based on 2D GLN‐functionalized WS2 QDs. These lasers may have a promising application in the field of flexible and wearable photonics, which is a critical step towards the development of next‐generation optoelectronic devices with improved performance.
Wrinkled graphene structure and localized surface plasmon resonance induced stretchable white random lasers have been demonstrated and their excellent capability for potential applications in the next‐generation information technology.
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