Evolution of Microstructural Characteristics of Carbonated Cement Pastes Subjected to High Temperatures Evaluated by MIP and SEM

The microstructural evolutions of both uncarbonated and carbonated cement pastes subjected to various high temperatures (30 degrees C, 200 degrees C, 400 degrees C, 500 degrees C, 600 degrees C, 720 degrees C, and 950 degrees C) are presented in this study by the means of mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). It was found that the thermal stabilities of uncarbonated cement pastes were significantly changed from 400 to 500 degrees C due to the decomposition of portlandite at this temperature range. More large pores and microcracks were generated from 600 to 720 degrees C, with the depolymerization of C-S-H. After carbonation, the microstructures of carbonated cement pastes remained unchanged below 500 degrees C and started to degrade at 600 degrees C, due to the decompositions of calcium carbonates and calcium modified silica gel. At 950 degrees C, both uncarbonated and carbonated cement pastes showed a loosely honeycombed microstructure, composed mainly of beta-C2S and lime. It can be concluded that carbonation improves the high-temperature resistance of cement pastes up to 500 degrees C, but this advantage is lost at temperatures over 600 degrees C

Slow-Binding Inhibition of the Aminopeptidase from \u3cem\u3eAeromonas proteolytica\u3c/em\u3e by Peptide Thiols: Synthesis and Spectroscopic Characterization

Peptide-derived thiols of the general structure N-mercaptoacyl-leucyl-p-nitroanilide (1a−c) were synthesized and found to be potent, slow-binding inhibitors of the aminopeptidase from Aeromonas proteolytica (AAP). The overall potencies (KI*) of these inhibitors against AAP range from 2.5 to 57 nM exceeding that of the natural product bestatin and approaching that of amastatin. The corresponding alcohols (2a−b) are simple competitive inhibitors of much lower potencies (KI = 23 and 360 μM). These data suggest that the free thiols are involved in the formation of the E·I and E·I* complexes, presumably serving as a metal ligand. To investigate the nature of the interaction of the thiol-based inhibitors with the dinuclear active site of AAP, we have recorded electronic absorption and EPR spectra of Co(II)Co(II)-, Co(II)Zn(II)-, and Zn(II)Co(II)-AAP in the presence of the strongest binding inhibitor, 1c. Both [CoZn(AAP)] and [ZnCo(AAP)], in the presence of 1c, exhibited an absorption band centered at 320 nm characteristic of an S → Co(II) ligand−metal charge-transfer band. In addition, absorption spectra recorded between 400 and 700 nm showed changes characteristic of 1c interacting with each active-site metal ion. EPR spectra recorded at high temperature (19 K) and low power (2.5 mW) indicated that in a given enzyme molecule, 1c interacts weakly with one of the metal ions in the dinuclear site and that the crystallographically identified μ-OH(H) bridge, which has been shown to mediate electronic interaction of the Co(II) ions, is likely broken upon 1c binding. EPR spectra of [CoCo(AAP)]-1c, [ZnCo(AAP)]-1c, and [CoZn(AAP)]-1c were also recorded at lower temperature (3.5−4.0 K) and high microwave power (50−553 mW). The observed signals were unusual and appeared to contain, in addition to the incompletely saturated contributions from the signals characterized at 19 K, a very sharp feature at geff ≈ 6.8 that is characteristic of thiolate-Co(II) interactions. These data suggest that the thiolate moiety can bind to either of the metal ions in the dinuclear active site of AAP but does not bridge the dinuclear cluster. Compounds 1a−c are readily accessible by synthesis and thus provide a novel class of potent aminopeptidase inhibitors

Coupled effects of moisture transport pathway and convection on stable isotopes in precipitation across the East Asian Monsoon Region: implications for paleoclimate reconstruction

This study investigated the variations in stable oxygen isotopes in daily precipitation (δ18Op) collected between 2010 and 2013 at four sites across the East Asian monsoon region to address the controversy whether local meteorological factors, moisture transport pathway, or convection dominates the δ18Op changes. We found that the δ18Op time series exhibit opposite seasonal patterns between the southern and northern sites; however, relatively low δ18Op values occur at each site during summer. The opposite seasonal patterns are closely related to the proportional change in the contributions from oceanic (>52% in the south) and continental (>85% in the north) moisture sources. Moisture transport distances also influence the seasonal δ18Op fluctuations. In the south, the moisture transported over short distances from the middle of the western Pacific Ocean results in relatively high δ18Op values during the premonsoon season. In contrast, long-distance transport of moisture from the Indian and equatorial Pacific Oceans during the monsoon season results in relatively low δ18Op values. In the north, relatively low δ18Op values during the monsoon season can be attributed to an increase in relatively distant moisture originating from the middle of the western Pacific Ocean. Convection only plays a role in affecting δ18Op values in the south during the monsoon season. Our study suggests that moisture transport pathway (moisture sources and moisture transport distances) is a major factor that governs seasonal variations in δ18Op across the East Asian monsoon region, which has implications for the interpretation of paleoclimate records from this region

Two-photon-transition superadiabatic passage in an nitrogen-vacancy center in diamond

Reaching a given target quantum state with high fidelity and fast operation speed close to the quantum limit represents an important goal in quantum information science. Here, we experimentally demonstrate superadiabatic quantum driving to achieve population transfer in a three-level solid-state spin system. Starting from traditional stimulated Raman adiabatic passage (STIRAP), our approach implements superadiabatic corrections to the STIRAP Hamiltonians with several paradigmatic pulse shapes. It requires no need of intense microwave pulses or long transfer times and shows enhanced robustness over pulse imperfections. These results might provide a useful tool for quantum information processing and coherent manipulations of quantum systems.Comment: 8 pages, 7 figure

Anti-HIV-1 Activity of a New Scorpion Venom Peptide Derivative Kn2-7

For over 30 years, HIV/AIDS has wreaked havoc in the world. In the absence of an effective vaccine for HIV, development of new anti-HIV agents is urgently needed. We previously identified the antiviral activities of the scorpion-venom-peptide-derived mucroporin-M1 for three RNA viruses (measles viruses, SARS-CoV, and H5N1). In this investigation, a panel of scorpion venom peptides and their derivatives were designed and chosen for assessment of their anti-HIV activities. A new scorpion venom peptide derivative Kn2-7 was identified as the most potent anti-HIV-1 peptide by screening assays with an EC50 value of 2.76 µg/ml (1.65 µM) and showed low cytotoxicity to host cells with a selective index (SI) of 13.93. Kn2-7 could inhibit all members of a standard reference panel of HIV-1 subtype B pseudotyped virus (PV) with CCR5-tropic and CXCR4-tropic NL4-3 PV strain. Furthermore, it also inhibited a CXCR4-tropic replication-competent strain of HIV-1 subtype B virus. Binding assay of Kn2-7 to HIV-1 PV by Octet Red system suggested the anti-HIV-1 activity was correlated with a direct interaction between Kn2-7 and HIV-1 envelope. These results demonstrated that peptide Kn2-7 could inhibit HIV-1 by direct interaction with viral particle and may become a promising candidate compound for further development of microbicide against HIV-1

Note on duality of weighted multi-parameter Triebel-Lizorkin spaces

summary:We study the duality theory of the weighted multi-parameter Triebel-Lizorkin spaces $\dot F^{\alpha ,q}_{p}(\omega ;\mathbb {R}^{n_{1}}\times \mathbb {R}^{n_{2}})$. This space has been introduced and the result $$(\dot F^{\alpha ,q}_{p}(\omega ;\mathbb {R}^{n_{1}}\times \mathbb {R}^{n_{2}}))^{\ast }= {\rm CMO}^{-\alpha ,q'}_{p}(\omega ;\mathbb {R}^{n_{1}}\times \mathbb {R}^{n_{2}})$$ for $0<p\leq 1$ has been proved in Ding, Zhu (2017). In this paper, for $1<p<\infty$, $0<q<\infty$ we establish its dual space $\dot H^{\alpha ,q}_{p}(\omega ;\mathbb {R}^{n_{1}}\times \mathbb {R}^{n_{2}})$

Novel Learning Algorithm based on BFE and ABC for Process Neural Network and its Application

In order to improve the generalization capability of process neural network (PNN), a novel learning algorithm is proposed based on basis function expansion (BFE) algorithm and artificial bee colony (ABC) algorithm, named BFE-ABC algorithm. First, the input functions and weight functions are simplified through BFE algorithm. The parameter space is transformed from function space to real number space in this way. Then, the PNN is designed to parametric representation through introducing two Boolean variables and one multidimensional parameter. At last, the multidimensional parameter composed of hidden neurons, expansion items and connection weights is optimized in real number space by ABC algorithm. BFE-ABC algorithm overcomes the premature problem and realizes the global optimization of the structure, connection weights and function expansion form at the same time. It is validated through the prediction experiment of Mackey-Glass chaotic time series. The test results in cylinder head temperature prediction prove the superiority of BFE-ABC algorithm over traditional learning algorithm and the applicability to time-dependent parameter prediction

Ecological Responses to Climate Change and Human Activities in the Arid and Semi-Arid Regions of Xinjiang in China

Understanding the impacts and extent of both climate change and human activities on ecosystems is crucial to sustainable development. With low anti-interference ability, arid and semi-arid ecosystems are particularly sensitive to disturbances from both climate change and human activities. We investigated how and to what extent climate variation and human activities influenced major indicators that are related to ecosystem functions and conditions in the past decades in Xinjiang, a typical arid and semi-arid region in China. We analyzed the changing trends of evapotranspiration (ET), gross primary productivity (GPP) and leaf area index (LAI) derived from the Moderate-Resolution Imaging Spectroradiometer (MODIS) satellite product and the Breathing Earth System Simulator (BESS) model in Xinjiang for different climate zones. We separated and quantified the contributions of climate forcing and human activities on the trends of the studied ecosystem indicators using the residual analysis method for different climate zones in Xinjiang. The results show that GPP and LAI increased and ET decreased from 2001 to 2015 in Xinjiang. Factors that dominate the changes in ecosystem indicators vary considerably across different climate zones. Precipitation plays a positive role in impacting vegetation indicators in arid and hyper-arid zones and temperature has a negative correlation with both GPP and LAI in hyper-arid zones in Xinjiang. Results based on residual analysis indicate that human activities could account for over 72% of variation in the changes in each ecosystem indicator. Human activities have large impacts on each vegetation indicator change in hyper-arid and arid zones and their relative contribution has a mean value of 79%. This study quantifies the roles of climate forcing and human activities in the changes in ecosystem indicators across different climate zones, suggesting that human activities largely influence ecosystem processes in the arid and semi-arid regions of Xinjiang in China