In-situ synthesis of single-atom Ir by utilizing metal-organic frameworks: An acid-resistant catalyst for hydrogenation of levulinic acid to γ-valerolactone

The hydrogenation of levulinic acid (LA) to gamma-valerolactone (GVL) is a key reaction for the production of renewable chemicals and fuels, wherein acid-resistant and robust catalysts are highly desired for practical usage. Herein, an ultra-stable 0.6 wt% Ir@ZrO2@C single-atom catalyst was prepared via an in-situ synthesis approach during the assembly of UiO-66, followed by confined pyrolysis. The Ir@ZrO2@C offered not only a quantitative LA conversion and an excellent GVL selectivity (>99%), but also an unprecedented stability during recycling runs under harsh conditions (at T= 453 K, P-H2 = 40 bar in pH = 3 or pH =1 aqueous solution). By thorough spectroscopy characterizations, a well-defined structure of atomically dispersed Ir delta+ atoms onto nano-tetragonal ZrO2 confined in the amorphous carbon was identified for the Ir@ZrO2@C. The strong metal-support interaction and the confinement of the amorphous carbon account for the ultra-stability of the Ir@ZrO2@C. (C) 2019 Elsevier Inc. All rights reserved

The Phosphate Fast-Responsive Genes <i>PECP1</i> and <i>PPsPase1</i> Affect Phosphocholine and Phosphoethanolamine Content

International audiencePhosphate starvation-mediated induction of the HAD-type phosphatases PPsPase1 (AT1G73010) and PECP1 (AT1G17710) has been reported in Arabidopsis (Arabidopsis thaliana). However, little is known about their in vivo function or impact on plant responses to nutrient deficiency. The preferences of PPsPase1 and PECP1 for different substrates have been studied in vitro but require confirmation in planta. Here, we examined the in vivo function of both enzymes using a reverse genetics approach. We demonstrated that PPsPase1 and PECP1 affect plant phosphocholine and phosphoethanolamine content, but not the pyrophosphate-related phenotypes. These observations suggest that the enzymes play a similar role in planta related to the recycling of polar heads from membrane lipids that is triggered during phosphate starvation. Altering the expression of the genes encoding these enzymes had no effect on lipid composition, possibly due to compensation by other lipid recycling pathways triggered during phosphate starvation. Furthermore, our results indicated that PPsPase1 and PECP1 do not influence phosphate homeostasis, since the inactivation of these genes had no effect on phosphate content or on the induction of molecular markers related to phosphate starvation. A combination of transcriptomics and imaging analyses revealed that PPsPase1 and PECP1 display a highly dynamic expression pattern that closely mirrors the phosphate status. This temporal dynamism, combined with the wide range of induction levels, broad expression, and lack of a direct effect on Pi content and regulation, makes PPsPase1 and PECP1 useful molecular markers of the phosphate starvation response

Functional analysis of phosphate starvation-regulated protein phosphatase and a general regulation factor (14-3-3) in plants

Phosphorus (P) is one of the most important but least available nutrients in the soil. Plants develop a host of morphological, physiological and biochemical adaptations to overcome persistent deficiency of phosphate (Pi). The molecular basis for these adaptations is the coordinated modulation of genes that may involve protein phosphorylation and dephosphorylation. In this study, two gene families involved in protein phosphorylation and dephosphorylation a putative protein phosphatase (PS2) and a plant general regulatory factor (14-3-3), were characterized by using reporter genes (β-glucuronidase and green fluorescent protein) and gene knockout and over-expression lines. The PS2 gene family has high similarity with the members of the HAD (haloacid dehalogenase) and DDDD (4 aspartate) super family of proteins with multiple functions. The family member in tomato (LePS2) is the first putative protein phosphatase gene shown to be regulated by Pi starvation in plants. Temporal and spatial expression of the 3 members of AtPS2 family in Arabidopsis revealed their functional specificity during Pi starvation. The gene expression in the cotyledonary leaves point to their potential role in mobilizing Pi during early seedling development. Altering the expression of PS2 genes resulted in metabolic changes such as altered Pi content, Pi uptake and phosphatase activity, and as well as phenotypic changes during the early growth stages. It also delayed tomato plant maturity and flowering. Considering the potential of PS2 members to function as phosphoprotein phosphatase, any significant alterations in their expression are likely to lead to changes in plant response to Pi deficiency. In contrast to induction of PS2 family members during Pi deficiency, many members of 14-3-3 family were suppressed under Pi limiting conditions. This response is specific and reversible by replenishment of Pi. Several Pi starvation regulated genes contain predicted 14-3-3 binding domain making them as potential targets for post-transcriptional modification. Accumulation of starch, generally observed under Pi deficiency, was suppressed by over-expression of 14-3-3 gene (GRF9) suggesting a negative correlation between gene expression and Pi starvation induced response. The outcome of this research shows that two key molecular determinants, whose expressions are altered under Pi deficiency could play a significant role in plant adaptation to this condition

Remote Sensing Analysis of Erosion in Arctic Coastal Areas of Alaska and Eastern Siberia

In this study, remote sensing analysis of coastal erosion is conducted for three typical regions of Alaska and Eastern Siberia based on remote sensing data collected between 1974 and 2017. The comparative studies were made on the difference in coastal erosion at different latitudes and the difference and influencing factors in coastal erosion at similar latitudes. The coastline retreatment is used to indicate coastal erosion. It is found that the most extensive erosion occurred along Alaska&rsquo;s coast, followed by that of the Eastern Siberian coasts. Based on the analysis of the historical time series of snow and ice as well as climate data, it is found that at similar latitudes, the erosion of the Arctic coasts is closely related to the trend and fluctuations of the sea surface temperature (SST). Specifically, it is found that in Alaska, coastal erosion is closely related to the fluctuation of the SST, while in Eastern Siberia, it is related to the increasing or decreasing trend of the SST. A decreasing trend is associated with low coastal erosion, whereas an increasing trend is associated with accelerated coastal erosion. In the Arctic, the strong fluctuations of the SST, the continuous decline of the sea ice cover, and the consequent increase of the significant wave height are the critical factors that cause changes in coastal permafrost and coastal erosion

Molecular identification and genetic characteristics of Cryptosporidium spp., Giardia duodenalis, and Enterocytozoon bieneusi in human immunodeficiency virus/acquired immunodeficiency syndrome patients in Shanghai, China

Abstract Background Opportunistic infections are a ubiquitous complication in human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) patients. Cryptosporidium spp., Giardia duodenalis, and Enterocytozoon bieneusi are common opportunistic intestinal pathogens in humans. In China, despite the number of HIV/AIDS patients being extremely large, only a few studies have investigated opportunistic infections caused by intestinal pathogens in this patient population. The aims of this study were to elucidate the occurrence and genetic characteristics of Cryptosporidium spp., G. duodenalis, and E. bieneusi in HIV/AIDS patients. Methods We collected fecal specimens from 155 HIV/AIDS patients (one from each patient). All of the specimens were examined for the presence of the pathogens by genotyping using polymerase chain reaction and sequencing of the small subunit ribosomal RNA gene for Cryptosporidium spp.; the triosephosphate isomerase, β-giardin and glutamate dehydrogenase genes for G. duodenalis; and the internal transcribed spacer region of the rRNA gene for E. bieneusi. The Cryptosporidium-positive specimens were further subtyped by polymerase chain reacion and sequencing of the 60-kDa glycoprotein gene. Results Six (3.9%), three (1.9%), and eight (5.2%) HIV/AIDS patients were positive for Cryptosporidium spp., G. duodenalis, and E. bieneusi, respectively. No statistical differences were observed in occurrence rate between the groups by gender, clinical symptom (diarrhea), and CD4+ cell count. Four Cryptosporidium species were identified: Cryptosporidium hominis (n = 2), Cryptosporidium parvum (n = 1), Cryptosporidium meleagridis (n = 1), and Cryptosporidium andersoni (n = 2). Furthermore, two C. hominis subtypes (IeA12G3T3 and IaA28R4) were detected. Three G. duodenalis-positive specimens were successfully amplified and sequenced at the triosephosphate isomerase and β-giardin loci, which led to the identification of assemblages C and B, respectively. Seven genotypes (D, Type IV, EbpC, Peru11, EbpD, A, and I) were identified in E. bieneusi-positive specimens. Conclusions Our findings should increase awareness of AIDS-related opportunistic intestinal pathogens, and indicate the need for routine examination in clinical practice for the detection of Cryptosporidium spp., G. duodenalis, and E. bieneusi. Homology analyses of the three intestinal pathogens at the nucleotide and/or amino acid levels indicated their zoonotic potential. Graphical Abstrac

Zeolite-supported metal catalysts for selective hydrodeoxygenation of biomass-derived platform molecules

Increasing demand for renewable chemicals and fuels has stimulated the search for alternative feedstocks and is driving the ongoing transition to a more renewables-based society. Considerable academic efforts have been directed at the valorisation of biomass sources and derived intermediates, so called platform molecules, to produce value-added chemicals and fuels. In this contribution, opportunities are discussed for the application of zeolite-supported bifunctional catalysts in the conversion of biomass sources into chemicals and fuels via hydrodeoxygenation (HDO). Such metal/zeolite catalyst systems play a prominent role in many of these biomass HDO routes. Emphasis is put on the current progress in metal/zeolite-catalysed HDO of three selected, promising routes involving biomass-derived platform molecules and the model compounds that mimic more complex feeds. Four key concepts of metal/zeolite catalysts, such as combining metal and Bronsted acid sites, site-ratio balancing, proximity between metal and acid functions and shape selectivity are discussed in order to provide a comprehensive overview. In addition, two challenges related to the accessibility of the active sites and catalyst stability in the liquid phase, typically a hot, highly polar, and protic reaction medium, are discussed. Finally, the open challenges and perspectives regarding the development of metal/zeolite catalysts for biomass HDO reactions are examined

Zeolite-supported metal catalysts for selective hydrodeoxygenation of biomass-derived platform molecules

Increasing demand for renewable chemicals and fuels has stimulated the search for alternative feedstocks and is driving the ongoing transition to a more renewables-based society. Considerable academic efforts have been directed at the valorisation of biomass sources and derived intermediates, so called platform molecules, to produce value-added chemicals and fuels. In this contribution, opportunities are discussed for the application of zeolite-supported bifunctional catalysts in the conversion of biomass sources into chemicals and fuels via hydrodeoxygenation (HDO). Such metal/zeolite catalyst systems play a prominent role in many of these biomass HDO routes. Emphasis is put on the current progress in metal/zeolite-catalysed HDO of three selected, promising routes involving biomass-derived platform molecules and the model compounds that mimic more complex feeds. Four key concepts of metal/zeolite catalysts, such as combining metal and Brønsted acid sites, site-ratio balancing, proximity between metal and acid functions and shape selectivity are discussed in order to provide a comprehensive overview. In addition, two challenges related to the accessibility of the active sites and catalyst stability in the liquid phase, typically a hot, highly polar, and protic reaction medium, are discussed. Finally, the open challenges and perspectives regarding the development of metal/zeolite catalysts for biomass HDO reactions are examined

Spatial Distribution Characteristics of Soil Salt Ions in Tumushuke City, Xinjiang

Concrete durability in saline soil areas is a global problem. Both SO42&minus; and Cl&minus; in saline soil seriously affect the durability of concrete and restrict the sustainable development of engineering construction. Soil samples were collected from Tumushuke city, Xinjiang, and the concentrations of SO42&minus; and Cl&minus; in the soil were measured. Classical statistics and geostatistics methods were combined to analyze the distribution characteristics of the soil salts. Additionally, the kriging interpolation method was used to draw a salt distribution map. The results showed that the average contents of SO42&minus; and Cl&minus; in the soil of this area were 7037.08 and 6018.94 mg/kg, respectively. SO42&minus; exhibited moderate variability at depths of 30&ndash;60 and 60&ndash;100 cm in the soil and strong variability in the surface layer; Cl&minus; exhibited strong variability at depths of 0&ndash;30, 30&ndash;60, and 60&ndash;100 cm in the soil. The SO42&minus; and Cl&minus; concentrations exhibited high spatial correlation and showed regular changes. The horizontal distribution patterns of &ldquo;low in the south and high in the north&rdquo; and &ldquo;high in the east and low in the west&rdquo; were observed. Regarding the vertical distribution, the profiles of the SO42&minus; and Cl&minus; contents in the soils primarily exhibited &ldquo;surface aggregation&rdquo; distribution characteristics. Therefore, according to the spatial distribution characteristics of SO42&minus; and Cl&minus;, local concrete engineering construction can adopt different anti-erosion measures to enhance the safety and durability of concrete structures

UiO-66 derived Ru/ZrO2@C as a highly stable catalyst for hydrogenation of levulinic acid to gamma-valerolactone

The hydrogenation of levulinic acid (LA) to gamma-valerolactone (GVL) is a crucial reaction included in many biorefinery schemes for the production of renewable chemicals and fuels. The development of highly stable supported Ru-based catalysts in the polar protic liquid phase under hydrothermal conditions is still a major challenge. Here, we prepared a 0.85 wt% Ru/ZrO2@C catalyst using a new stabilization strategy based on the UiO-66 (Zr-MOF) material. The catalytic performance of this Ru/ZrO2@C in LA-to-GVL was tested and compared with commercial 5 wt% Ru/C at 10 bar H-2, 413 K in water and also in high protic aqueous solution (pH = 1). The full conversion of LA and quantitative yield of GVL were achieved with both catalysts. However, the 5 wt% Ru/C showed poor resistance to deactivation already after the first run. ICP, XPS, HRTEM, AC-STEM, TPR and physisorption data showed that quick deactivation of Ru/C was mainly caused by the leaching of ruthenium in addition to the loss of surface area via carbonaceous deposition in micro-pores. In contrast, the self-prepared Ru/ZrO2@C catalyst showed no apparent drop in catalytic performance either in water or in high protic aqueous solution upon multiple recycling, and no leaching of ruthenium was found even under harsh conditions (pH = 1). Remarkably, in the Ru/ZrO2@C catalyst, Ru (probable single-atom) was highly dispersed on nanotetragonal ZrO2 (3.3 nm), embedded in the amorphous carbon, and no apparent Ru nanoclusters were observed even after reactions. TPR results indicated that this excellent stability might be attributed to strong metal-support interaction between Ru and nanotetragonal ZrO2

A retrospective epidemiological analysis of human Cryptosporidium infection in China during the past three decades (1987-2018).

BackgroundCryptosporidiosis is an emerging infectious disease of public health significance worldwide. The burden of disease caused by Cryptosporidium varies between and within countries/areas. To have a comprehensive understanding of epidemiological status and characteristics of human Cryptosporidium infection in China since the first report in 1987, a retrospective epidemiological analysis was conducted by presenting differences in the prevalence of Cryptosporidium by province, year, population, living environment and season and possible transmission routes and risk factors as well as genetic characteristics of Cryptosporidium in humans.Methodology/principal findingsA systematic search was conducted to obtain epidemiological papers of human Cryptosporidium infection/cryptosporidiosis from PubMed and Chinese databases. Finally, 164 papers were included in our analysis. At least 200,054 people from 27 provinces were involved in investigational studies of Cryptosporidium, with an average prevalence of 2.97%. The prevalence changed slightly over time. Variable prevalences were observed: 0.65-11.15% by province, 1.89-47.79% by population, 1.77-12.87% and 0-3.70% in rural and urban areas, respectively. The prevalence peak occurred in summer or autumn. Indirect person-to-person transmission was documented in one outbreak of cryptosporidiosis in a pediatric hospital. 263 Cryptosporidium isolates were obtained, and seven Cryptosporidium species were identified: C. hominis (48.3%), C. andersoni (22.43%), C. parvum (16.7%), C. meleagridis (8.36%), C. felis (3.04%), C. canis (0.76%) and C. suis (0.38%).Conclusions/significancesThis systematic review reflects current epidemiological status and characteristics of Cryptosporidium in humans in China. These data will be helpful to develop efficient control strategies to intervene with and prevent occurrence of human Cryptosporidium infection/cryptosporidiosis in China as well as have a reference effect to other countries. Further studies should focus on addressing a high frequency of C. andersoni in humans and a new challenge with respect to cryptosporidiosis with an increasing population of elderly people and patients with immunosuppressive diseases