Physicochemical properties constitute a key factor for the success of a drug candidate. Whereas many strategies to improve the physicochemical properties of small heterocycle-type leads exist, ...complex hydrocarbon skeletons are more challenging to derivatize because of the absence of functional groups. A variety of CH oxidation methods have been explored on the betulin skeleton to improve the solubility of this very bioactive, yet poorly water-soluble, natural product. Capitalizing on the innate reactivity of the molecule, as well as the few molecular handles present on the core, allowed oxidations at different positions across the pentacyclic structure. Enzymatic oxidations afforded several orthogonal oxidations to chemical methods. Solubility measurements showed an enhancement for many of the synthesized compounds.
A two-stage micro-impinging stream reactor（TS-MISR） that combined a first pre-mixing stage with a second micro-impinging stream reacting stage for continuous multi-component reacting systems has been ...built from commercial T-junctions and steel micro-capillaries. Both of operating parameters and reactor configurations,such as jet Reynolds number（Rej）, volumetric flow ratio（R）, the first-stage junction angle（φ）, the connecting capillary length（Lc） and connecting capillary diameter（dc）, had significant effects on the micromixing efficiency of the reactor. Such effects were investigated for both of the two stage structures, respectively, by experimental and CFD methods and were optimized for the best micromixing performance. Intensified micromixing among at least three reacting components can be achieved in a continuous mode by using TS-MISR; therefore, it is expected that the TS-MISR will produce products of higher quality with more uniform and stable element distribution.
Multi-variable and non-linear features for wastewater treatment process (WTP), traditional expert experience-based decision making scheme can not well express the WTP. To overcome the challenge, this ...paper proposes to build Robotic Decision scheme based on joint awareness of knowledge and data for modeling of WTP. Firstly, Modeling WTP by knowledge modeling system and neural network modeling system respectively. After that, Establish a collaboration awareness layer to ingeniously combine knowledge model with data model. At last, a series of experiments are carried out on a dataset obtained from a realistic wastewater treatment plant, in order to evaluate the performance and reliability of the proposed RD-ACL. The results show that the proposal improves modeling efficiency compared with typical existing methods. Through such a collaborative modeling scheme, intelligent management degree of WTP can be improved to some extent.
Microbial reduction of ethyl 1-benzyl-3-oxo-piperidine-4-carboxylate by the majority of evaluated microorganisms gave the ethyl
cis-(3
R,4
R)-1-benzyl-3
R-hydroxy-piperidine-4
R-carboxylate as the ...major product in high diastereo- and enantioselectivities. The 3
R,4
R-hydroxy ester was produced in 97.4% diastereomeric excess (de) and 99.8% enantiomeric excess (ee) by
Candida parapsilosis SC16347, while 99.5% de and 98.2% ee were obtained from reduction by
Pichia methanolica SC16415. A few of the evaluated microorganisms gave 10–40% of the ethyl
trans-(3
R,4
S)-1-benzyl-3
R-hydroxy-piperidine-4
S-carboxylate as the minor product.
This paper proposes a desirable method to detect different kinds of low probability of intercept (LPI) radar signals, targeted at the main intra-pulse modulation method of LPI radar signals including ...the signals of linear frequency modulation, phase code, and frequency code. Firstly, it improves the coherent integration of LPI radar signals by adding the periodicity of the ambiguity function. Then, it develops a frequency domain detection method based on fast Fourier transform (FFT) and segmented autocorrelation function to detect signals without features of linear frequency modulation by virtue of the distribution characteristics of noise signals in the frequency domain. Finally, this paper gives a verification of the performance of the method for different signal-to-noise ratios by conducting simulation experiments, and compares the method with existing ones. Additionally, this method is characterized by the straightforward calculation and high real-time performance, which is conducive to better detecting all kinds of LPI radar signals.
In this paper, we present a new dataset with the target of advancing temporal real-world event detection from video-sharing social media. The collected temporal event dataset (TED) has certain ...characteristics. 1) Certainty of event labels that can be recognized as real-world happening. 2) Wide range of event categories covering public security, natural disasters, elections, sports and entertainment events, etc. 3) High overlap among event topics ensuring the difficulties in distinguishing the labels. 4) Multiple data modalities involving textual, acoustic, and visual information, etc. More specifically, two scenarios are defined based on the close or open domains, i.e., temporal event detection without/with new events, denoted as TED-W and TED-N, respectively. For comparisons, a few benchmarks are investigated on the two scenarios with the dataset.
With the continuous progress of communication quality, the wireless vehicular networks (WVN) will surely be-come an inevitable part of future smart cities. Inside WVN where context is complicated and ...stochastic, quality of service (QoS) acts as the core concern for broad users. And reliable prediction towards traffic in WVN is essentially an important demand to ensure QoS. Conventionally, related methods mainly focus one side to establish robust prediction models, possessing some limitations. To bridge such gap, model integration may be an intuitive and promising solution. This paper proposes QoS-aware reliable traffic prediction model under WVN (TP-WVN). Firstly, two typical prediction models are used as fundamental learners, which can capture the spatial correlations from different angles. Then, regression model is selected as the integrator to combine base models together. Simulative experiments on a real-world dataset are conducted to evaluate the proposal, and results show that the TP-WVN is able to realize reliable QoS-aware prediction compared with baseline methods.
Photonic topological edge states in one-dimensional dimer chains have long been thought to be robust to structural perturbations by mapping the topological Su-Schrieffer-Heeger model of a solid-state ...system. However, the edge states at the two ends of a finite topological dimer chain will interact as a result of near-field coupling. This leads to deviation from topological protection by the chiral symmetry from the exact zero energy, weakening the robustness of the topological edge state. With the aid of non-Hermitian physics, the splitting frequencies of edge states can be degenerated again and topological protection recovered by altering the gain or loss strength of the structure. This point of coalescence is known as the exceptional point (EP). The intriguing physical properties of EPs in topological structures give rise to many fascinating and counterintuitive phenomena. In this work, based on a finite non-Hermitian dimer chain composed of ultra-subwavelength resonators, we propose theoretically and verify experimentally that the sensitivity of topological edge states is greatly affected when the system passes through the EP. Using the EP of a non-Hermitian dimer chain, we realize a new sensor that is sensitive to perturbation at the end of the structure and yet topologically protected from internal perturbation. Our demonstration of a non-Hermitian topological structure with an EP paves the way for the development of novel sensors that are not sensitive to internal manufacturing errors but are highly sensitive to changes in the external environment.
Physicochemical properties constitute a key factor for the success of a drug candidate. Whereas many strategies to improve the physicochemical properties of small heterocycle‐type leads exist, ...complex hydrocarbon skeletons are more challenging to derivatize because of the absence of functional groups. A variety of CH oxidation methods have been explored on the betulin skeleton to improve the solubility of this very bioactive, yet poorly water‐soluble, natural product. Capitalizing on the innate reactivity of the molecule, as well as the few molecular handles present on the core, allowed oxidations at different positions across the pentacyclic structure. Enzymatic oxidations afforded several orthogonal oxidations to chemical methods. Solubility measurements showed an enhancement for many of the synthesized compounds.
Oxidationen nach Wunsch: Verschiedene C‐H‐Oxidationsmethoden wurden am Betulin‐Gerüst ausprobiert, um die Löslichkeit dieses biologisch aktiven, aber schlecht wasserlöslichen Naturstoffs zu verbessern. Die immanente Reaktivität des Moleküls sowie das Vorliegen mehrerer funktionalisierbarer Stellen am Strukturkern ermöglichten Oxidationen an unterschiedlichen Stellen der Struktur. Viele der synthetisierten Verbindungen zeigten eine verbesserte Löslichkeit.
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