ALBERT

Description: With a pace of about twice the observed rate of global warming, the temperature on the Qinghai-Tibetan Plateau (Earth's “third pole”) has increased by 0.2 °C per decade over the past 50 years, which results in significant permafrost thawing and glacier retreat. Our review suggested that warming enhanced net primary production (NPP) and soil respiration, decreased methane (CH 4 ) emissions from wetlands and increased CH 4 consumption of meadows, but might increase CH 4 emissions from lakes. Warming induced permafrost thawing and glaciers melting would also result in substantial emission of old carbon dioxide (CO 2 ) and CH 4 . Nitrous oxide (N 2 O) emission was not stimulated by warming itself, but might be slightly enhanced by wetting. However, there are many uncertainties in such biogeochemical cycles under climate change. Human activities (e.g., grazing, land cover changes) further modified the biogeochemical cycles and amplified such uncertainties on the plateau. If the projected warming and wetting continues, the future biogeochemical cycles will be more complicated. So facing research in this field is an ongoing challenge of integrating field observations with process-based ecosystem models to predict the impacts of future climate change and human activities at various temporal and spatial scales. To reduce the uncertainties and improve the precision of the predictions of the impacts of climate change and human activities on biogeochemical cycles, efforts should focus on conducting more field observation studies, integrating data within improved models, and developing new knowledge about coupling among carbon, nitrogen, and phosphorus biogeochemical cycles as well as about the role of microbes in these cycles. This article is protected by copyright. All rights reserved.

Description: Vegetation indices (VIs) derived from satellite reflectance measurements are often used as proxies of canopy activity to evaluate the impacts of drought and heatwave on gross primary production (GPP) through production efficiency models (PEMs). However, GPP is also regulated by physiological processes that cannot be directly detected using reflectance measurements. This study analyzes the co-limitation of canopy and plant physiology (represented by VIs and climate anomalies, respectively) on GPP during 2003 European summer drought and heatwave for 15 Euroflux sites. During the entire drought period, spatial pattern of GPP anomalies can be quantified by relative changes in VIs. We also find that GPP sensitivity to relative canopy changes is higher for non-forest ecosystems (1.81 ±0.32 %GPP/%EVI), while GPP sensitivity to physiological changes is higher for forest ecosystems (−0.18±0.05 g C m -2 day -1 /hPa). A conceptual model is further built to better illustrate the canopy and physiological controls on GPP during drought periods.

Description: This study examined the difference of vegetation indices (VIs), evapotranspiration (ET), gross primary production (GPP), and solar‐induced chlorophyll fluorescence (SIF) during 2000–2010 between pure grasslands (PG) and juniper‐encroached grasslands (JEG). The changes of GPP and ET for grasslands with different proportions of juniper encroachment (JWPE) were also assessed. The results suggested mean annual GPP and ET were ~55% and ~45% higher when grasslands were completely converted into juniper forests under contemporary climate during 2000–2010. The enhancement of annual GPP and ET for grasslands with JWPE varied over years in association with the moisture conditions. Abstract Woody plant encroachment (WPE) into grasslands has been occurring globally and may be accelerated by climate change in the future. This land cover change is expected to alter the carbon and water cycles, but it remains uncertain how and to what extent the carbon and water cycles may change with WPE into grasslands under current climate. In this study, we examined the difference of vegetation indices (VIs), evapotranspiration (ET), gross primary production (GPP), and solar‐induced chlorophyll fluorescence (SIF) during 2000–2010 between grasslands and juniper‐encroached grasslands. We also quantitatively assessed the changes of GPP and ET for grasslands with different proportions of juniper encroachment (JWPE). Our results suggested that JWPE increased the GPP, ET, greenness‐related VIs, and SIF of grasslands. Mean annual GPP and ET were, respectively, ~55% and ~45% higher when grasslands were completely converted into juniper forests under contemporary climate during 2000–2010. The enhancement of annual GPP and ET for grasslands with JWPE varied over years ranging from about +20% GPP (~+30% for ET) in the wettest year (2007) to about twice as much GPP (~+55% for ET) in the severe drought year (2006) relative to grasslands without encroachment. Additionally, the differences in GPP and ET showed significant seasonal dynamics. During the peak growing season (May–August), GPP and ET for grasslands with JWPE were ~30% and ~40% higher on average. This analysis provided insights into how and to what degree carbon and water cycles were impacted by JWPE, which is vital to understanding how JWPE and ecological succession will affect the regional and global carbon and water budgets in the future.

Description: Abstract Luminescent readout capability for photochromic materials plays a critical role in 3D optical data storage applications, especially for inorganic photochromic materials in the solid‐state form. In our previous studies, we found that the luminescent readout capability can be improved using two or multiple‐photon excited luminescent mode (upconversion), which can effectively decrease the destruction degree of the excitation energies to the stored information during the luminescent “reading” process. However, the luminescent readout performance is unsatisfactory owing to the absence of nondestructive luminescence readout capability. Herein, we report a new solid‐state photochromic material with excellent upconversion readout capability: Ho3+/Yb3+ codoped (K,Na)NbO3. Upon 407 nm light irradiation, the luminescent switching contrast (ΔRt) is up to 78%. Particularly, the materials almost have no any re‐absorption to 980 nm light, exhibiting extremely low destruction to information recording points. The luminescent readout intensity retains 96% after constant 980 nm irradiation for 4 minutes at a high pumping power of 1W, which is superior to our previously reported results (Er/Yb codoped Bi2.5Na0.5Nb2O9 materials). This work would help to further develop new inorganic photochromic materials with high performance to satisfy the requirements for optical storage devices.

Description: To test the hypothesis that particle composition has a stronger influence on the community structure of particle-attached than free-living bacteria, elemental (C/N, δ 13 C, and δ 15 N) and chemical composition of particles and the size-fractionated bacterial community composition were examined along the particle density gradient from the Pearl River to the open basin in the South China Sea. Microbial communities were collected at the three size fractions of 0.2–0.8, 0.8–3, and 〉3 µm and the community composition was analyzed using high-throughput sequencing of the 16S rRNA gene (V3–V4 regions). Multivariate analysis evaluating the similarities of bacterial community composition and chemical composition of particles revealed their general consistent spatial variations along the particle density gradient from freshwater to the sea basin. However, compositions of particulate organic matter were more strongly related to the free-living than to the particle-attached bacterial community composition, which was composed of relatively abundant anaerobic bacteria and those taxa preferring low-oxygen conditions. This latter result might be caused by low-oxygen micro-zones in particles. Community network models further revealed tighter interactions within the particle-attached than in free-living bacterial communities, suggesting that a relatively confined space in particles is more favorable for interactions within the community. These analyses indicated that particle micro-niche properties might be important in shaping particle-attached community structure. In contrast, particulate organic matter compositions significantly influenced the free-living bacterial community probably through the release of labile or semi-labile organic matter from particles contributing to the bioavailability of dissolved organic carbon.

Description: Vitamin A (VA) and its active form, retinoic acid (RA), are regulators of skeletal development and chondrogenesis. MafB, a transcription factor, has been identified as an important mediator in monocyte and osteoclast differentiation. However, the presence and function of MafB in chondrocytes is not clear. In this study, MafB gene expression was regulated by both the VA status of the mother (VA-marginal, adequate, and supplemented diets) and by direct oral supplementation of the neonates with VARA (VA mixed with 10% RA). Expression was highest in neonates of VA-supplemented versus VA-marginal dams ( P 〈0.05), and in VARA-treated versus placebo-treated neonates across all diet groups ( P 〈0.05). To examine cellular changes, primary chondrocytes derived from neonatal rat ribs were cultured in the presence of RA for up to 48 h. MafB mRNA exhibited a time- and dose-dependent increase in response to RA, while the induction of MafB mRNA was attenuated by BMS-493, a pan-RAR inverse agonist, implicating RAR signaling in the regulation of MafB. The genetic knockdown of MafB in chondrocytes using siRNA (MafB SI chondrocytes) abrogated the RA-induced increase in MafB expression. MafB SI chondrocytes expressed higher levels of aggrecan mRNA. Additionally, the increased matrix metalloproteinase (MMP)3 and MMP13 gene expression due to RA was attenuated in MafB SI chondrocytes, while total extracellular matrix staining was increased. These results support a role for MafB as a regulator of chondrocyte gene expression and matrix formation via control of aggrecan, MMP3 and MMP13 expression, and indicate an important role for RA in the regulation of MafB. J. Cell. Biochem. © 2012 Wiley Periodicals, Inc.

Description: Five new limonoids, aphagranols D–H ( 1 – 5 , resp.), were isolated from the EtOH extract of the fruits of Aphanamixis grandifolia by chromatographic methods. Their structures were established on the basis of extensive spectroscopic analyses. The absolute configuration of 1 was determined by comparison the experimental and calculated electronic circular dichroism (ECD) spectra. All of the isolates were evaluated for insecticidal activities.

Description: Microwave dielectric properties and thermally stimulated depolarization currents (TSDC) of (1− x ) Ba 0.6 Sr 0.4 La 4 Ti 4 O 15 – x TiO 2 ( x  =   0, 0.01, 0.02, 0.05, and 0.1) ceramics were studied. X-ray diffraction analysis indicates that the specimens show a hexagonal perovskite structure; however, with an increase of x to 0.1, TiO 2−δ as a secondary phase can be detected in the ceramics. The variation of TiO 2 content has a significant effect on the dielectric properties of (1− x ) Ba 0.6 Sr 0.4 La 4 Ti 4 O 15 – x TiO 2 at microwave frequency. The dielectric permittivity of ceramics increases from 44 to 49 with the increase of TiO 2 content. The Qf value is in the range of 39 300–53 400 GHz. However, the temperature coefficient of resonant frequency (τ f ) changes from −7.5 to–9.4 ppm/°C, and then turns to +3.9 ppm/°C. A near zero τ f value can be obtained by tuning the content of TiO 2 addition. TSDC was also employed to analysis the extrinsic loss mechanism. Utilizing a fixed polarization condition, the TSDC relaxation peaks are present, which are generated by oxygen vacancies. And the concentration of oxygen vacancies increases with the increase of TiO 2 content. It can be concluded that the extrinsic dielectric loss is dominated by microstructure and oxygen vacancy defects.

Description: Abstract The global budget of marine nitrogen (N) is not balanced, with N removal largely exceeding N fixation. One of the major causes of this imbalance is our inadequate understanding of the diversity and distribution of marine N2 fixers (diazotrophs) as well as their contribution to N2 fixation. Here, we performed a large‐scale cross‐system study spanning the South China Sea, Luzon Strait, Philippine Sea, and western tropical Pacific Ocean to compare the biogeography of seven major diazotrophic groups and N2 fixation rates in these ecosystems. Distinct spatial niche differentiation was observed. Trichodesmium was dominant in the South China Sea and western equatorial Pacific, whereas the unicellular cyanobacterium UCYN‐B dominated in the Philippine Sea. Furthermore, contrasting diel patterns of Trichodesmium nifH genes and UCYN‐B nifH gene transcript activity were observed. The heterotrophic diazotroph Gamma A phylotype was widespread throughout the western Pacific Ocean and occupied an ecological niche that overlapped with that of UCYN‐B. Moreover, Gamma A (or other possible unknown/undetected diazotrophs) rather than Trichodesmium and UCYN‐B may have been responsible for the high N2 fixation rates in some samples. Regional biogeochemistry analyses revealed cross‐system variations in N2‐fixing community composition and activity constrained by sea surface temperature, aerosol optical thickness, current velocity, mixed‐layer depth, and chlorophyll a concentration. These factors except for temperature essentially control/reflected iron supply/bioavailability and thus drive diazotroph biogeography. This study highlights biogeographical controls on marine N2 fixers and increases our understanding of global diazotroph biogeography.

Description: With the development of modern society, science and technology, information technology and computer technology have been developing rapidly. The computer simulation technology is mainly to use the electronic computer to carry out simulation work, which is expected to provide new research work for the research and production of material science and to raise the development of material science to a new level. Therefore, the author mainly analyzes the application of computer simulation technology in material science, and hopes to provide some suggestions and references for the development of material science through the author’s elaboration.