Flood control of the Yangtze River is an important part of China’s national water security. In July 2020, due to continuous heavy rainfall, the water levels along the middle-lower reaches of the ...Yangtze River and major lakes constantly exceeded the warning levels, in which Taihu Lake exceeded its highest safety water level and some stations of Poyang Lake reached their highest water levels in its history. In August 2020, another huge flood occurred in the Minjiang River and the Jialing River in the upper Yangtze River, and some areas of Chongqing Municipality and other cities along the rivers were inundated, resulting in great pressure on flood control and high disaster losses. The 2020 Yangtze River flood has received extensive media coverage and raised concerns on the roles of the Three Gorges Dam and other large reservoirs in flood control. Here we analyze the changes in the pattern of the Yangtze River flood control by comparing the strategies to tackle the three heavy floods occurring in 1954, 1998, and 2020. We propose that the overall strategy of the Yangtze River flood control in the new era should adhere to the principle of “Integration of storage and drainage over the entire Yangtze River Basin, with draining floods downstream as the first priority” by using both engineering and non-engineering measures. On the basis of embankments, the engineering measures should use the Three Gorges Dam and other large reservoirs as the major regulatory means, promote the construction of key flood detention areas, keep the floodways clear, and maintain the ecosystem services of wetlands and shoals. In terms of non-engineering measures, we should strengthen adaptive flood risk management under climate change, standardize the use of lands in flood detention areas, give space to floods, and promote the implementation of flood risk maps and flood insurance policies. The ultimate goal of this new flood control system is to enhance the adaptability to frequent floods and increase the resilience to extreme flood disasters.
Enantiopure molecules based on macrocyclic architecture are unique for applications in enantioselective host‐guest recognition, chiral sensing and asymmetric catalysis. Taking advantage of the chiral ...transfer from the intrinsically planar chirality of pillar5arenes, we herein present an efficient and straightforward approach to achieve early examples of highly luminescent chiral systems (P5NN and P5BN). The optical resolution of their enantiomers has been carried out via preparative chiral HPLC, which was ascribed to the molecular functionalization of pillar5arenes with π‐conjugated, sterically bulky triarylamine (Ar3N) as an electron donor and triarylborane (Ar3B) as an acceptor. This crucial design enabled investigations of the chiroptical properties, including circular dichroism (CD) and circularly polarized luminescence (CPL) in the solid state. The intramolecular charge transfer (ICT) nature in P5BN afforded an interesting thermochromic shift of the emission over a wide temperature range.
Two examples of planar chiral systems were achieved by axial functionalization of a pillar5arene with sufficiently bulky, rigid, π‐conjugated and highly luminescent triarylborane and triarylamine moieties, leading to enantiomeric resolution and circularly polarized luminescence (CPL). They represent the first chiral luminescent systems based on planar chiral pillar5arenes.
•Chinese school children, ages 9–10, were surveyed across an urbanization gradient.•Mounted specimens were used to measure children’s attitudes towards animals.•We also measured contact with nature ...and general attitudes towards conservation.•Children’s contact with nature was generally lower in more urban situations.•Contact with nature affected willingness to conserve animals by mediating biophilia.
The widening gap between humans and nature, driven by urbanization, seems to be an indisputable fact in the modern world. Such a gap may breed apathy towards environmental concerns and wildlife, which would not bode well for the future of biodiversity conservation. However, the consequences of the decline in physical contact with nature are poorly understood, especially in China, which is urbanizing faster than any other country. In this study, we aimed to understand how contact with nature affects children’s propensity for biophilia and biophobia, and their conservation attitudes. Fifteen schools with different degrees of urbanization were selected and 1119 pupils aged 9–10 filled out questionnaires. The students reported how frequently they engaged in fifteen outdoor activities, and these scores were summed together to produce a measurement of their contact with nature. The participants were shown twelve specimens of common wild animals in order to examine their biophilia and biophobia, and their willingness to conserve animals. We found children from urban schools had less contact with nature than those from rural schools, although this result was only marginally significant because of one outlying rural school. The children’s contact with nature was significantly positively related to their biophilia and negatively related to their biophobia. Children’s biophilia, in turn, significantly affected their willingness to conserve animals, and, to a lesser extent, their general attitudes about conservation. As a whole, the study suggests that contact with nature may enhance children’s willingness to support animal conservation indirectly by nurturing biophilic attitudes to wildlife.
Although maternal deaths are rare in developed regions, the morbidity associated with severe postpartum hemorrhage (SPPH) remains a major problem. To determine the prevalence and risk factors of ...SPPH, we analyzed data of women who gave birth in Guangzhou Medical Centre for Critical Pregnant Women, which received a large quantity of critically ill obstetric patients who were transferred from other hospitals in Southern China.
In this study, we conducted a retrospective case-control study to determine the prevalence and risk factors for SPPH among a cohort of women who gave birth after 28 weeks of gestation between January 2015 and August 2019. SPPH was defined as an estimated blood loss ≥1000 mL and total blood transfusion≥4 units. Logistic regression analysis was used to identify independent risk factors for SPPH.
SPPH was observed in 532 mothers (1.56%) among the total population of 34,178 mothers. Placenta-related problems (55.83%) were the major identified causes of SPPH, while uterine atony without associated retention of placental tissues accounted for 38.91%. The risk factors for SPPH were maternal age < 18 years (adjusted OR aOR = 11.52, 95% CI: 1.51-87.62), previous cesarean section (aOR = 2.57, 95% CI: 1.90-3.47), history of postpartum hemorrhage (aOR = 4.94, 95% CI: 2.63-9.29), conception through in vitro fertilization (aOR = 1.78, 95% CI: 1.31-2.43), pre-delivery anemia (aOR = 2.37, 95% CI: 1.88-3.00), stillbirth (aOR = 2.61, 95% CI: 1.02-6.69), prolonged labor (aOR = 5.24, 95% CI: 3.10-8.86), placenta previa (aOR = 9.75, 95% CI: 7.45-12.75), placenta abruption (aOR = 3.85, 95% CI: 1.91-7.76), placenta accrete spectrum (aOR = 8.00, 95% CI: 6.20-10.33), and macrosomia (aOR = 2.30, 95% CI: 1.38-3.83).
Maternal age < 18 years, previous cesarean section, history of PPH, conception through IVF, pre-delivery anemia, stillbirth, prolonged labor, placenta previa, placental abruption, PAS, and macrosomia were risk factors for SPPH. Extra vigilance during the antenatal and peripartum periods is needed to identify women who have risk factors and enable early intervention to prevent SPPH.
Optical microfibers (MF), as a connection between fiber optics and nanotechnology, can realize enhanced light-matter/environment interactions, which benefit for optical sensing applications. In this ...paper, we introduce the fundamental working mechanisms of MF-based optical sensors and review their recent progress and status. We also discuss the challenges and opportunities of the MF sensors and provide some clues for future work.
A considerable amount of platinum (Pt) is required to ensure an adequate rate for the oxygen reduction reaction (ORR) in fuel cells and metal‐air batteries. Thus, the implementation of atomic Pt ...catalysts holds promise for minimizing the Pt content. In this contribution, atomic Pt sites with nitrogen (N) and phosphorus (P) co‐coordination on a carbon matrix (PtNPC) are conceptually predicted and experimentally developed to alter the d‐band center of Pt, thereby promoting the intrinsic ORR activity. PtNPC with a record‐low Pt content (≈0.026 wt %) consequently shows a benchmark‐comparable activity for ORR with an onset of 1.0 VRHE and half‐wave potential of 0.85 VRHE. It also features a high stability in 15 000‐cycle tests and a superior turnover frequency of 6.80 s−1 at 0.9 VRHE. Damjanovic kinetics analysis reveals a tuned ORR kinetics of PtNPC from a mixed 2/4‐electron to a predominately 4‐electron route. It is discovered that coordinated P species significantly shifts d‐band center of Pt atoms, accounting for the exceptional performance of PtNPC.
Phosphorus‐coordinated atomic Pt‐Nx sites are theoretically predicted and experimentally realized, offering enhanced kinetics for four‐electron electrochemical oxygen reduction. Exceptional activity is attributed to the tuning of the d‐band electron center via local coordination asymmetry. This chemistry provides an effective guideline for atomic Pt catalysts in batteries and fuel cells.
Producing indispensable hydrogen and oxygen for social development via water electrolysis shows more prospects than other technologies. Although electrocatalysts have been explored for centuries, a ...universal activity descriptor for both hydrogen‐evolution reaction (HER) and oxygen‐evolution reaction (OER) is not yet developed. Moreover, a unifying concept is not yet established to simultaneously understand HER/OER mechanisms. Here, the relationships between HER/OER activities in three common electrolytes and over ten representative material properties on 12 3d‐metal‐based model oxides are rationally bridged through statistical methodologies. The orbital charge‐transfer energy (Δ) can serve as an ideal universal descriptor, where a neither too large nor too small Δ (≈1 eV) with optimal electron‐cloud density around Fermi level affords the best activities, fulfilling Sabatier's principle. Systematic experiments and computations unravel that pristine oxide with Δ ≈ 1 eV possesses metal‐like high‐valence configurations and active lattice‐oxygen sites to help adsorb key protons in HER and induce lattice‐oxygen participation in the OER, respectively. After reactions, partially generated metals in the HER and high‐valence hydroxides in the OER dominate proton adsorption and couple with pristine lattice‐oxygen activation, respectively. These can be successfully rationalized by the unifying orbital charge‐transfer theory. This work provides the foundation of rational material design and mechanism understanding for many potential applications.
A universal activity descriptor (orbital charge‐transfer energy) is successfully extracted from various materials’ physicochemical properties for both hydrogen‐evolving and oxygen‐evolving reactions in multiple electrolytes. Systematic experiments and computations reveal the life‐cycle HER and OER mechanisms and identify the unifying orbital charge‐transfer theory as a powerful mechanism analysis tool and foundation.
Chiral macrocycles possess significant value in chiral science and supramolecular chemistry. Pillararenes, as a class of relatively young supramolecular macrocyclic hosts, have been widely used for ...host-guest recognition and self-assembly. Since the position of substituents on the benzene rings breaks the molecular symmetry (symmetric plane and symmetric center), pillararenes possess planar chirality. However, it is a great challenge to synthesize stable and resolvable enantiomers because of the easy rotation of the phenylene group. In this review, we summarize the construction methods of resolvable chiral pillararenes. We also focus on their applications in enantioselective recognition, chiral switches, chirality sensing, asymmetric catalysis, circularly polarized luminescence, metal-organic frameworks, and highly permeable membranes. Finally, we discuss the future research perspectives in this field of pillararene-based planar chiral materials. We hope that this review will encourage more researchers to work in this exciting field.
This review overviews recent research in the planar chiral pillararene field in terms of enantioselective recognition, chiral switches, chirality sensing, asymmetric catalysis, metal-organic frameworks, circularly polarized luminescence, and permeable membranes.
A common set of functional characteristics of cancer cells is that cancer cells consume a large amount of glucose, maintain high rate of glycolysis and convert a majority of glucose into lactic acid ...even in the presence of oxygen compared to that of normal cells (Warburg's Effects). In addition, cancer cells exhibit substantial alterations in several energy metabolism pathways including glucose transport, tricarboxylic acid (TCA) cycle, glutaminolysis, mitochondrial respiratory chain oxidative phosphorylation and pentose phosphate pathway (PPP). In the present work, we focused on reviewing the current knowledge about the dysregulation of the proteins/enzymes involved in the key regulatory steps of glucose transport, glycolysis, TCA cycle and glutaminolysis by several oncogenes including c-Myc and hypoxia inducible factor-1 (HIF-1) and tumor suppressor, p53, in cancer cells. The dysregulation of glucose transport and energy metabolism pathways by oncogenes and lost functions of the tumor suppressors have been implicated as important biomarkers for cancer detection and as valuable targets for the development of new anticancer therapies.
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