The shape-selective catalysis enabled by zeolite micropore's molecular-sized sieving is an efficient way to reduce the cost of chemical separation in the chemical industry. Although well studied ...since its discovery, HZSM-5's shape-selective capability has never been fully exploited due to the co-existence of its different-sized straight channels and sinusoidal channels, which makes the shape-selective p-xylene production from toluene alkylation with the least m-xylene and o-xylene continue to be one of the few industrial challenges in the chemical industry. Rather than modifications which promote zeolite shape-selectivity at the cost of stability and reactivity loss, here inverse Al zoned HZSM-5 with sinusoidal channels predominantly opened to their external surfaces is constructed to maximize the shape-selectivity of HZSM-5 sinusoidal channels and reach > 99 % p-xylene selectivity, while keeping a very high activity and good stability ( > 220 h) in toluene methylation reactions. The strategy shows good prospects for shape-selective control of molecules with tiny differences in size.
With the increasing concern about climate change, the Kigali Amendment to the Montreal protocol requires parties to gradually reduce high global warming potential (GWP) hydrofluorocarbon (HFC) use by ...80–85% by the late 2040s. The US Environmental Protection Agency (EPA) and EU Directive 517/2014 are also setting the ban on the use of such refrigerants. R134a, as a high GWP (GWP
100
:1300) HFC refrigerant, is a commonly used medium pressure chiller refrigerant that will be phased out. Searching for low GWP R134a alternatives is necessary. In this study, hydrofluoroolefin blends-R513A, R513B, R515A, R515B, R516A and pure hydrofluoroolefins-R1234yf and R1234ze(E) are investigated for performance evaluation for two-stage centrifugal chiller application with a fixed cooling capacity 1,750 kW. The evaluation was conducted via a thermodynamic process model, a component sizing methodology and a life cycle environmental performance methodology R515A, R515B and R1234ze(E) show a 25% volume capacity reduction in comparison with baseline due to their low suction density. All R134a alternatives exhibit more component heat transfer area than baseline, with 5–15% increase for the evaporator and 12–38% for the condenser. The comparison for the compressor impeller diameter shows that R513A, R513B, and R516A do not require the compressor size change from baseline, while R515A, R515B and R1234ze(E) need a more than 18% larger compressor size. R134a alternatives can provide 8.4–16.7% life cycle emission reduction in China and 14.7–27.7% in South Korea. In general, R513A, R513B and R516A are more preferable R134a drop-in options for less component modification and the same compressor can be employed directly. R516A is A2L and necessary vessel safety code protection is needed. R515A and R515B can serve as the system newly design-based interim non-flammable replacement for R134a in medium-pressure chillers with a large modification for a compressor. Gradually, with more strict regulations, R1234ze(E) can be the ultimate option in the market with less/negligible modification from R515A and R515B. For R1234yf, its poor heat transfer performance and high price can impede its application in chillers. It is anticipated that the viewpoints and insights from this study can be beneficial for the engineers, policymakers, scholars, public and manufacturers to maintain the maximum sustainability and economic benefits.
Over the past three years, a particularly exciting and active area of research within the field of organic photovoltaics has been the use of non-fullerene acceptors (NFAs). Compared with fullerene ...acceptors, NFAs possess significant advantages including tunability of bandgaps, energy levels, planarity and crystallinity. To date, NFA solar cells have not only achieved impressive power conversion efficiencies of ~13–14%, but have also shown excellent stability compared with traditional fullerene acceptor solar cells. This Review highlights recent progress on single-junction and tandem NFA solar cells and research directions to achieve even higher efficiencies of 15–20% using NFA-based organic photovoltaics are also proposed.
A well-preserved spinicaudatan species, Yanjiestheria huajiyingensis sp. nov., is here described from the Huajiying Formation in northern Hebei, northern China. The species is characterized by the ...transverse ridges in the postero-ventral part of the carapace. The preserved eggs in the new species aid in identifying sexual dimorphism in Yanjiestheria.
•A new spinicaudatan species was recovered from the Lower Cretaceous Huajiying Formation.•Fossil eggs aid in identifying sexual dimorphism in Yanjiestheria.•According to new data the Huajiying Formation may contain both early and middle Jehol Biota.
This paper presents an experimental study on a semi-active hybrid energy storage system consisting of a battery pack and a supercapacitor pack for electric vehicle application. First, a real-time ...energy management control strategy based on a combination of filtering and fuzzy logic controller is proposed. The main advantage of the proposed control strategy is that the peak current of the battery can be obviously reduced while ensuring the voltage of the supercapacitor fluctuates within a certain desired range. Second, a 30 kW rated power experimental platform is constructed, in which only one dc/dc converter is used to regulate the power flow between the battery and the supercapacitor. Finally, a corrected battery fade model, which can accurately match the studied battery, is used to analyze the battery fade behavior. The results reveal that the battery capacity fade cost of the hybrid energy storage system can be reduced by 44.42%, 30.44%, and 57.16% compared with the sole battery storage under new European drive cycle, highway driving cycle, and Indian urban driving cycle, three driving cycles, respectively.
Psychological health problems, especially emotional disorders, are common among adolescents. The epidemiology of emotional disorders is greatly influenced by stressful events. This study sought to ...assess the prevalence rate and socio-demographic correlates of depressive and anxiety symptoms among Chinese adolescents affected by the outbreak of COVID-19. We conducted a cross-sectional study among Chinese students aged 12–18 years during the COVID-19 epidemic period. An online survey was used to conduct rapid assessment. A total of 8079 participants were involved in the study. An online survey was used to collect demographic data, assess students’ awareness of COVID-19, and assess depressive and anxiety symptoms with the Patient Health Questionnaire (PHQ-9) and the Generalized Anxiety Disorder (GAD-7) questionnaire, respectively. The prevalence of depressive symptoms, anxiety symptoms, and a combination of depressive and anxiety symptoms was 43.7%, 37.4%, and 31.3%, respectively, among Chinese high school students during the COVID-19 outbreak. Multivariable logistic regression analysis revealed that female gender was the higher risk factor for depressive and anxiety symptoms. In terms of grades, senior high school was a risk factor for depressive and anxiety symptoms; the higher the grade, the greater the prevalence of depressive and anxiety symptoms. Our findings show there is a high prevalence of psychological health problems among adolescents, which are negatively associated with the level of awareness of COVID-19. These findings suggest that the government needs to pay more attention to psychological health among adolescents while combating COVID-19.
Short-term combined use of clopidogrel and aspirin improves cerebrovascular outcomes in patients with symptomatic extracranial or intracranial stenosis. Antiplatelet non-responsiveness is related to ...recurrent ischemic events, but the culprit genetic variants responsible for the non-responsiveness have not been well studied. We aimed to identify the genetic variants associated with poor clinical outcomes.
Patients with symptomatic extracranial or intracranial stenosis scheduled for stenting and receiving dual antiplatelets (clopidogrel 75 mg and aspirin 100 mg daily) for at least 5 days before intervention were enrolled. Ischemic events including recurrent transient ischemic attack, stroke, myocardial infarction, and vascular-related mortality within 12 months follow-up were recorded. We examined the influence of genetic polymorphisms on treatment outcome in our patients.
A total of 268 patients were enrolled into our study and ischemic events were observed in 39 patients. For rs662 of paraoxonase 1 (PON1), allele C was associated with an increased risk of ischemic events (OR = 1.64, 95%CI = 1.03-2.62, P = 0.029). The A-allele carriers of rs2046934 of P2Y12 had a significant association with adverse events (OR = 2.01, 95%CI = 1.10-3.67, P = 0.041). The variant T-allele of cyclooxygenase-1 (COX1) rs1330344 significantly increased the risk of recurrent clinical events (OR = 1.85, 95%CI = 1.12-3.03, P = 0.017). The other single nucleotide polymorphism (SNP) had no association with ischemic events.
PON1, P2Y12 and COX1 polymorphisms were associated with poorer vascular outcomes. Testing for these polymorphisms may be valuable in the identification of patients at risk for recurrent ischemic events.
Inclusive Monte-Carlo samples are indispensable for signal selection and background suppression in many high energy physics experiments. A clear knowledge of the physics processes involved in the ...samples, including the types of processes and the number of processes in each type, is a great help to investigating signals and backgrounds. To help analysts obtain the physics process information from the truth information of the samples, we develop a physics process analysis program, TopoAna, with C++, ROOT, and LaTeX. The program implements the functionalities of component analysis and signal identification with many kinds of fine, customizable classification and matching algorithms. It tags physics processes in individual events accurately in the output root files, and exports the physics process information at the sample level clearly to the output plain text, tex source, and pdf files. Independent of specific software frameworks, the program is applicable to many experiments. At present, it has come into use in three e+e− colliding experiments: the BESIII, Belle, and Belle II experiments. The use of the program in other similar experiments is also prospective.
Program title: TopoAna
CPC Library link to program files:http://dx.doi.org/10.17632/hjg4d9c843.1
Licensing provisions: MIT
Programming language: C++
Nature of problem: A clear knowledge of the physics processes involved in inclusive Monte-Carlo samples is a great help to investigating signals and backgrounds in many high energy physics experiments. However, the raw topology truth information of the samples is counter-intuitive, diverse, and overwhelming, which makes it difficult for analysts to check the physics process information of the samples directly.
Solution method: Based on accurate pattern matching, many kinds of fine, customizable classification and matching algorithms are implemented in this program, in order to help analysts obtain the physics process information of the samples from their raw truth information.
Unusual features: Besides the C++ Standard Template Library, this program makes use of ROOT 1, a C++ based data analysis software universally used in modern high energy physics experiments. In addition, the program employs the Linux command, pdflatex, to compile the tex source files into the pdf documents.
References
1 ROOT User’s Guide, Available online: https://root.cern/root/htmldoc/guides/users-guide/ROOTUsersGuide.html.
The coronavirus disease 2019 (COVID-19) outbreak impacts physical and mental health. The purpose of this study was to explore the association between the levels of social support and mental health ...among Chinese adolescents during the outbreak.
A total of 7,202 adolescents aged 14–18 years completed online survceys from March 8 to 15, 2020, in China. Researchers assessed the associations between depression symptoms (Patient Health Questionnaire-9), anxiety symptoms (Chinese version of the 7-item Generalized Anxiety Disorder scale), and social support (Social Support Rate Scale).
COVID-19 exposure was associated with a higher prevalence of depression symptoms (odds ratio OR = 1.38, 95% confidence interval CI: 1.14–1.66) and anxiety symptoms (OR = 1.26, 95% CI: 1.04–1.52). Only 24.6% of adolescents reported high levels of social support. Most adolescents (70%) reported medium levels of support, and 5.4% reported low support. Low support was associated with higher prevalence of depression (OR = 4.24, 95% CI: 3.38–5.33) and anxiety symptoms (OR = 3.18, 95% CI: 2.54–3.98), while controlling for gender, grade, living situation, and COVID-19 exposure; similarly, medium support was associated with higher prevalence of depression (OR = 2.79, 95% CI: 2.48–3.15) and anxiety (OR = 2.19, 95% CI: 1.94–2.48) symptoms.
This study indicates there is a higher prevalence of mental health problems among adolescents with medium and low levels of social support in China during the outbreak of COVID-19.
This brief presents a nonlinear control design for a two-wheeled inverted pendulum robot, based on new analysis of the classical state-dependent Riccati equation (SDRE) scheme and a novel alternative ...strategy. The solvability of pointwise algebraic Riccati equations (AREs) corresponding to the nonunique state-dependent coefficients (SDCs) of the SDRE scheme is analyzed from a new perspective. This is formulated as a simple equivalence condition with reduced dimensionality, which circumvents the excessive online computational effort to check the solvability of classical SDRE. The condition is derived in a way to facilitate the generalization to all meaningful SDCs. Moreover, due to unsolvable AREs, all conflicts against the primary objective of posture balance of the robot are revealed and illustrated, with a connection to the robot physical parameters. At the system states that cause such conflicts and other unsolvable AREs, a simple analytical solution via alternative SDC constructions is suggested. More potential advantages of this SDC construction over the classical scheme are revealed in simulations, e.g., the maximum input/torque and total energy consumption.
PDF
