Future scenarios with significant anthropogenic climate change also display large increases in world production of fossil fuels, the principal CO2 emission source. Meanwhile, fossil fuel depletion ...has also been identified as a future challenge. This chapter reviews the connection between these two issues and concludes that limits to availability of fossil fuels will set a limit for mankind's ability to affect the climate. However, this limit is unclear as various studies have reached quite different conclusions regarding future atmospheric CO2 concentrations caused by fossil fuel limitations.
It is concluded that the current set of emission scenarios used by the IPCC and others is perforated by optimistic expectations on future fossil fuel production that are improbable or even unrealistic. The current situation, where climate models largely rely on emission scenarios detached from the reality of supply and its inherent problems are problematic. In fact, it may even mislead planners and politicians into making decisions that mitigate one problem but make the other one worse. It is important to understand that the fossil energy problem and the anthropogenic climate change problem are tightly connected and need to be treated as two interwoven challenges necessitating a holistic solution.
► Review of the development of emission scenarios. ► Survey of future fossil fuel trajectories used by the IPCC emission scenarios. ► Discussions on energy transitions in the light of oil depletion. ► Review of earlier studies of future climate change and fossil fuel limitations.
To characterize the pore features of outburst coal samples and investigate whether outburst coal has some unique features or not, one of the authors, working as the member of the State Coal Mine ...Safety Committee of China, sampled nine outburst coal samples（coal powder and block） from outburst disaster sites in underground coal mines in China, and then analyzed the pore and surface features of these samples using low temperature nitrogen adsorption tests. Test data show that outburst powder and block coal samples have similar properties in both pore size distribution and surface area. With increasing coal rank, the proportion of micropores increases, which results in a higher surface area. The Jiulishan samples are rich in micropores, and other tested samples contain mainly mesopores, macropores and fewer micropores. Both the unclosed hysteresis loop and force closed desorption phenomena are observed in all tested samples. The former can be attributed to the instability of the meniscus condensation in pores,interconnected pore features of coal and the potential existence of ink-bottle pores, and the latter can be attributed to the non-rigid structure of coal and the gas affinity of coal.
The Moon has a magmatic and thermal history that is distinct from that of the terrestrial planets
. Radioisotope dating of lunar samples suggests that most lunar basaltic magmatism ceased by around ...2.9-2.8 billion years ago (Ga)
, although younger basalts between 3 Ga and 1 Ga have been suggested by crater-counting chronology, which has large uncertainties owing to the lack of returned samples for calibration
. Here we report a precise lead-lead age of 2,030 ± 4 million years ago for basalt clasts returned by the Chang'e-5 mission, and a
U/
Pb ratio (µ value)
of about 680 for a source that evolved through two stages of differentiation. This is the youngest crystallization age reported so far for lunar basalts by radiometric dating, extending the duration of lunar volcanism by approximately 800-900 million years. The µ value of the Chang'e-5 basalt mantle source is within the range of low-titanium and high-titanium basalts from Apollo sites (µ value of about 300-1,000), but notably lower than those of potassium, rare-earth elements and phosphorus (KREEP) and high-aluminium basalts
(µ value of about 2,600-3,700), indicating that the Chang'e-5 basalts were produced by melting of a KREEP-poor source. This age provides a pivotal calibration point for crater-counting chronology in the inner Solar System and provides insight on the volcanic and thermal history of the Moon.
With the development of science, speech, picture, and other analysis, problems have been gradually better solved, but the study of Chinese text has been a complex problem to overcome. Chinese text ...analysis requires not only statistics but also semantic comprehension analysis. Different text types need other language style feature modeling to obtain good recognition results. In this study, we use the deep learning method to construct an automatic text feature extraction model and classify it with the author as a classification label. This study presents a literature author recognition model based on deep learning, which is mainly divided into three phases: text preprocessing, feature extraction, and classification. Each part consists of several small modules or steps. First, we input the corpus to Word2Vec to generate the new word vector. Then, the improved text feature extractor based on CNN and Attention extracts the text features and uses them as the input of the CNN convolution layer. After convolution, the text is combined with bits to get Window Feature Sequence. It is the text feature vector. Next, based on LSTM and Softmax classification output, Window Feature Sequence is used as the input of LSTM to obtain two one-dimensional vectors spliced by concatenate layer. Finally, the result is classified through the fully connected layer, Batch Normalization layer, and Softmax. The performance of the proposed model in recognizing authors of Chinese literature was evaluated using two datasets. In the research process, the data we collected included works of different forms, such as prose and fiction. The research results show that the proposed model can effectively identify author identity. The classification accuracy of our proposed algorithm is significantly better than that of the benchmark model.
Micrometeorite impacts and solar wind irradiation, the dominant space weathering (SW) processes, largely modified compositions and microtexture of soil materials on the Moon. Here, we report the SW ...characteristics of the Chang'e‐5 lunar soils from mid‐high latitude (43.06°N). All mineral phases exposed on the surface of a single basalt clast have a vapor deposit layer, whereas the textures of the solar wind irradiation‐damaged zone are dependent on the host mineral species. Nanophase Fe (npFe0) particles are spherical in the amorphized zone of pyroxenes, elongated in ilmenite, and irregular on the jagged surface of iron sulfide, but not found in Fe‐poor merrillite. Vesicles were found in the damaged zone of ilmenite and merrillite, but with different shapes. The observations were compared to Apollo samples and demonstrate no significant altitude‐dependent effects on the SW, which is important for decoding the reflectance spectra of the Moon.
Plain Language Summary
The lunar surface has been suffering intense meteorite impacts and solar wind irradiation for billions of years, which heavily modifies its physical properties, chemical compositions and mineralogical features, and in turn, the optical reflectance spectra of the Moon. The meteorite impacts are random events, but the intensity of solar wind irradiation is latitude dependent. However, all Apollo and Luna missions landed in a narrow and low range of lunar latitude. The Chang'e‐5 (CE‐5) mission returned lunar soil samples from a middle latitude (43.06°N), providing unique samples for study of lunar space weathering (SW). In this paper, we report the SW features of various minerals from a single basaltic clast of the CE‐5 sample. Our observations reveal phase‐dependent effects on the SW. Furthermore, the CE‐5 lunar soil shows no significant differences from those of Apollo samples, suggestive of little latitude‐dependent effects on lunar SW.
Key Points
The space weathering (SW) characteristics of lunar soils returned by Chang'e‐5 landing at the mid‐high latitude site are reported
Microscopic textures of SW depend on mineral species but show no relationship with the latitude of sampling site
The SW products by micrometeorite impacts and solar wind irradiation are distinguished
Multiple studies have reported different methods in treating gestational diabetes mellitus (GDM); however, the relationship between miR‐335‐5p and GDM still remains unclear. Here, this study explores ...the effect of miR‐335‐5p on insulin resistance and pancreatic islet β‐cell secretion via activation of the TGFβ signaling pathway by downregulating VASH1 expression in GDM mice. The GDM mouse model was established and mainly treated with miR‐335‐5p mimic, miR‐335‐5p inhibitor, si‐VASH1, and miR‐335‐5p inhibitor + si‐VASH1. Oral glucose tolerance test (OGTT) was conducted to detect fasting blood glucose (FBG) fasting insulin (FINS). The OGTT was also used to calculate a homeostasis model assessment of insulin resistance (HOMA‐IR). A hyperglycemic clamp was performed to measure the glucose infusion rate (GIR), which estimated β‐cell function. Expressions of miR‐335‐5p, VASH1, TGF‐β1, and c‐Myc in pancreatic islet β‐cells were determined by RT‐qPCR, western blot analysis, and insulin release by ELISA. The miR‐335‐5p mimic and si‐VASH1 groups showed elevated blood glucose levels, glucose area under the curve (GAUC), and HOMA‐IR, but a reduced GIR and positive expression of VASH1. Overexpression of miR‐335‐5p and inhibition of VASH1 contributed to activated TGFβ1 pathway, higher c‐Myc, and lower VASH1 expressions, in addition to downregulated insulin and insulin release levels. These findings provided evidence that miR‐335‐5p enhanced insulin resistance and suppressed pancreatic islet β‐cell secretion by inhibiting VASH1, eventually activating the TGF‐β pathway in GDM mice, which provides more clinical insight on the GDM treatment.
miR‐335‐5p enhanced insulin resistance and suppressed pancreatic islet β‐cell secretion by inhibiting VASH1, eventually activating the TGF‐β pathway in GDM mice, which provides more clinical insight on the GDM treatment.
Due to frequent changes in the humid and hot environment, the residual soil with a particle-size distribution (PSD) from gravel to clay experiences multiple drying–wetting cycles. The pressure plate ...test and nuclear magnetic resonance (NMR) spectroscopy were used to investigate the influence of drying–wetting cycles on the soil–water characteristic curve (SWCC) and pore-size distribution (POSD) of undisturbed residual soil. The results showed that the water-holding capacity of the residual soil decreased as the number of drying–wetting cycles increased and gradually stablilized, and then the van Genuchten (VG) model was found to perform well on the SWCC during the drying–wetting processes. The NMR results indicated a double-pore structure, and the porosity of the residual soil as well as the internal water content increased smoothly with more drying–wetting cycles. The obtained POSD curve of soil implied that drying–wetting cycles had a more obvious effect on small pores and macro-pores than on micro-pores and meso-pores. Theoretical calculations evinced that the product of the matric suction and relaxation time should be constant at a constant temperature. However, the experimental results did not effectively reflect such a relation between the matric suction and relaxation time. A modified VG model based on the cumulative pore volume was utilized to describe the POSD under drying–wetting cycles. Subsequently, the proposed Rational2D surface equation was used to accurately reflect the internal relationship between the SWCC and POSD curve under different numbers of drying–wetting cycles. Moreover, the fractal model for the SWCC derived from the capillary theory confirmed that the matric suction had a strong linear relationship with the relative volumetric water content in the log-log scale. Also, the fractal dimension can be approximated as a constant, because its attenuation is small with more drying–wetting cycles.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
A near-infrared (NIR) single-photon detector for direct time-of-flight (dTOF) measurement is proposed based on <inline-formula> <tex-math notation="LaTeX">0.18 ~\mu \text{m} ...</tex-math></inline-formula> BCD technology. The integrated single-photon avalanche diode (SPAD) adopts a high-voltage p-well (HVPW)/high-voltage buried n+ (HVBN) layer as a deep-junction multiplication region to significantly enhance the NIR photon detection probability (PDP). Meanwhile, a virtual guard ring formed by the low doping p-type epitaxial layer is used to effectively minimize dark count noise. In particular, a compact time-to-amplitude converter (TAC) combined with an asynchronous counter is employed to realize a time-to-amplitude-digital hybrid conversion for gaining higher time resolution and larger dynamic range, simultaneously. The experimental results demonstrate that at 5 V excess bias voltage, the NIR PDP at 905 nm wavelength is up to 7.9%, and the dark count rate (DCR) is below 10 Hz at room temperature. Furthermore, the detector obtains a time resolution of 39 ps and a time full-scale range (FSR) of <inline-formula> <tex-math notation="LaTeX">2.56 ~\mu \text{s} </tex-math></inline-formula>, with a differential nonlinearity (DNL) and integral nonlinearity (INL) less than ±1 LSB, respectively. The proposed single-photon dTOF detector exhibits the significant advantages of high sensitivity, low noise, high time resolution, and large FSR, which is very fit for low-cost and high-precision dTOF measurement systems.
Psychological stress is an important factor for the development of irritable bowel syndrome(IBS). More and more clinical and experimental evidence showed that IBS is a combination of irritable bowel ...and irritable brain. In the present review we discuss the potential role of psychological stress in the pathogenesis of IBS and provide comprehensive approaches in clinical treatment. Evidence from clinical and experimental studies showed that psychological stresses have marked impact on intestinal sensitivity, motility, secretion and permeability, and the underlying mechanism has a close correlation with mucosal immune activation, alterations in central nervous system, peripheral neurons and gastrointestinal microbiota. Stress-induced alterations in neuro-endocrine-immune pathways acts on the gut-brain axis and microbiota-gut-brain axis, and cause symptom flare-ups or exaggeration in IBS. IBS is a stresssensitive disorder, therefore, the treatment of IBS should focus on managing stress and stress-induced responses. Now, non-pharmacological approaches and pharmacological strategies that target on stress-related alterations, such as antidepressants, antipsychotics, miscellaneous agents, 5-HT synthesis inhibitors, selective 5-HT reuptake inhibitors, and specific 5-HT receptor antagonists or agonists have shown a critical role in IBS management. A integrative approach for IBS management is a necessary.
•A novel porous structure with N defect g-C3N4 was synthesized.•The DCN-P showed enhanced CO2 reduction activity.•The DCN-F can broaden the light harvest and narrowed band gap.
A novel porous ...structure g-C3N4 with nitrogen defect photocatalysts (DCN-P) was successfully prepared by in-situ doping strategy and freeze-dried method, it exhibits enhanced photo-reduction CO2 performance with satisfactory CO, CH4 productivity about 19.7 umol g−1, 37.1 umol g−1, which is more higher than that of bulk g-C3N4 (B-CN). Systematically characterization demonstrated that the synergistic effect of unique porous structure and the nitrogen defection in DCN-P can effect enhance CO2 adsorption, increase reactive sites, improve optical absorption and narrowed band gap of g-C3N4, which is supported by both experimental and density functional theory (DFT) calculations results. More importantly, this work provides a new ideas for constructing other high-performance metal-free photocatalytic systems for CO2 reduction.
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