•The inter-core coupling strength of weakly-coupled multicore fiber can be strengthened by tapering method.•The transmission spectra of the proposed sensor vary with environmental temperature due to ...thermo-optic effects and thermal expansion effects of multicore fiber.•The annealing techniques should be adopted to eliminate the effect of residual stress in the sensor and improve the high-temperature sustainability of the sensor.
A novel high temperature sensor based on weakly-coupled multicore fiber (MCF) is proposed and experimentally demonstrated. The sensor consists of a taper of weakly-coupled MCF sandwiched between two standard single-mode fibers (SMF). The temperature sensing mechanism is investigated theoretically and experimentally. In order to eliminate the effect of residual stress in the sensor and improve the high-temperature sustainability of the sensor, the annealing techniques for the proposed sensor is also investigated. The sensor annealed via the proposed techniques was demonstrated experimentally to be able to measuring temperatures up to 1000 °C with sensitivity of ∼36.8 pm/°C.
In nature, prenylation and geranylation are two important metabolic processes for the creation of hemiterpenoids and monoterpenoids under enzyme catalysis. Herein, we have demonstrated bioinspired ...unnatural prenylation and geranylation of oxindoles using the basic industrial feedstock isoprene through ligand regulation under Pd catalysis. Pentenylated oxindoles (with C5 added) were attained with high selectivity when using a bisphosphine ligand, whereas upon switching to a monophosphine ligand, selectivity toward geranylated oxindoles (with C10 added) was achieved. Moreover, the head‐to‐head product could be further isomerized to an internal skipped diene under Pd−H catalysis. No stoichiometric by‐product was formed in the process.
A practical strategy has been developed for the bioinspired and ligand‐regulated chemoselective unnatural prenylation and geranylation of oxindoles with isoprene under Pd catalysis. The selectivity was governed by modulating the coordination geometry of the Pd catalyst.
Anthrones and analogues are structural cores shared by diverse pharmacologically active natural and synthetic compounds. The sp2‐rich nature imposes inherent obstruction to introduce stereogenic ...element onto the tricyclic aromatic backbone. In our pursuit to expand the chemical space of axial chirality, a novel type of axially chiral anthrone‐derived skeleton was discovered. This work establishes oxime ether as suitable functionality to furnish axial chirality on symmetric anthrone skeletons through stereoselective condensation of the carbonyl entity with long‐range chirality control. The enantioenriched anthrones could be elaborated into dibenzo‐fused seven‐membered N‐heterocycles containing well‐defined stereogenic center via Beckmann rearrangement with axial‐to‐point chirality conversion.
By a simple stereoselective condensation with remote chirality control, axial chirality could be introduced to the symmetric anthrone backbones that comprise mostly sp2‐hybridized carbons. The generated oxime ether functionality enables their transformation with axial‐to‐point chirality conversion via Beckmann rearrangement into enantioenriched dibenzo‐fused seven‐membered N‐heterocycles.
This paper addresses the problem of maximizing coverage in a mission space with both stationary and mobile agents such that effective coverage constraints are satisfied, i.e., each point of the ...mission space must be covered to a predefined level at least once over a given time period. The deployment of the stationary agents may be given in advance or may be obtained by a classical coverage control algorithm. The motion planning of the mobile agents is designed under maximal speed and acceleration constraints. When there is only one mobile agent, it is shown that its path planning and velocity planning can be designed separately. We first obtain an optimal velocity policy and the corresponding optimal coverage performance for a given path, which provides a criterion to prescribe a good path. Then, path planning is generated to meet the effective coverage constraint by connecting a set of “inspection points”. Inspired by the optimal velocity policy, we propose three methods to generate the inspection points and obtain the optimal order of connecting the inspection points by a Traveling Salesman Problem (TSP)-based method. Finally, we extend the one-mobile-agent motion planning scheme to multiple mobile agents by proposing two methods. Simulation examples are included to compare the performance of the three methods for generating inspection points and compare the performance of the proposed methods for multiple mobile agents.
Trauma-induced osteonecrosis of the femoral head (TIONFH) is a major complication of femoral neck fractures. Degeneration and necrosis of subchondral bone can cause collapse, which results in hip ...joint dysfunction in patients. The destruction of bone metabolism homeostasis is an important factor for osteonecrosis. MicroRNAs (miRNAs) have an important role in regulating osteogenic differentiation, but the mechanisms underlying abnormal bone metabolism of TIONFH are poorly understood. In this study, we screened specific miRNAs in TIONFH by microarray and further explored the mechanism of osteogenic differentiation.
Blood samples from patients with TIONFH and patients without necrosis after trauma were compared by microarray, and bone collapse of necrotic bone tissue was evaluated by micro-CT and immunohistochemistry. To confirm the relationship between miRNA and osteogenic differentiation, we conducted cell culture experiments. We found that many miRNAs were significantly different, including miR-93-5p; the increase in this miRNA was verified by Q-PCR. Comparison of the tissue samples showed that miR-93-5p expression increased, and alkaline phosphatase (ALP) and osteopontin (OPN) levels decreased, suggesting miR-93-5p may be involved in osteogenic differentiation. Further bioinformatics analysis indicated that miR-93-5p can target bone morphogenetic protein 2 (BMP-2). A luciferase gene reporter assay was performed to confirm these findings. By simulating and/or inhibiting miR-93-5p expression in human bone marrow mesenchymal stem cells, we confirmed that osteogenic differentiation-related indictors, including BMP-2, Osterix, Runt-related transcription factor, ALP and OPN, were decreased by miR-93-5p.
Our study showed that increased miR-93-5p in TIONFH patients inhibited osteogenic differentiation, which may be associated with BMP-2 reduction. Therefore, miR-93-5p may be a potential target for prevention of TIONFH.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Attitude determination involves the integration of methodologies and systems for estimating the time varying attitude of moving objects. Strapdown Inertial Attitude Measurement System (SIAMS) is ...among the most widely used navigation systems. The development of cost effective Micro Electro Mechanic System (MEMS) based inertial sensors has made attitude measurement system more affordable. However, MEMS sensors suffer from various errors that have to be calibrated and compensated to get acceptable attitude results. Given the auto-compensation of inertial sensor bias in rotation error modulation, the objective of this paper is to develop a MEMS-based rotary SIAMS, in which the significant sensor bias is automatically compensated by rotating the IMU, to offer comparable performance with respect to a tactical-grade Inertial Measurement Unit (IMU). With the analysis of the relationship between the MEMS error and misalignment, a MEMS calibration model is derived, and a combined calibration method of multi position rotation is applied to estimate the deterministic sensor errors such as bias, scale factor, and misalignment. Simulation and experiment results indicate that the proposed method can further modulate and compensate the MEMS errors, thereby improving the MEMS attitude accuracy.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Extracellular vesicles (EVs) are small lipid bilayer-delimited nanoparticles released from all types of cells examined thus far. Several groups of EVs, including exosomes, microvesicles, and ...apoptotic bodies, have been identified according to their size and biogenesis. With extensive investigations on EVs over the last decade, it is now recognized that EVs play a pleiotropic role in various physiological processes as well as pathological conditions through mediating intercellular communication. Most notably, EVs have been shown to be involved in cancer initiation and progression and EV signaling in cancer are viewed as potential therapeutic targets. Furthermore, as membrane nanoparticles, EVs are natural products with some of them, such as tumor exosomes, possessing tumor homing propensity, thus leading to strategies utilizing EVs as drug carriers to effectively deliver cancer therapeutics. In this review, we summarize recent reports on exploring EVs signaling as potential therapeutic targets in cancer as well as on developing EVs as therapeutic delivery carriers for cancer therapy. Findings from preclinical studies are primarily discussed, with early phase clinical trials reviewed. We hope to provide readers updated information on the development of EVs as cancer therapeutic targets or therapeutic carriers.
The first asymmetric Wolff rearrangement reaction that directly converts α-diazoketones into broadly useful chiral α,α-disubstituted carboxylic esters with high enantioselectivities (up to 97.5:2.5 ...er) is reported. The cascade reaction proceeds through the seamless combination of visible-light-induced formation of the ketene intermediate and asymmetric ketene esterification using a readily available benzotetramisole-type catalyst.
Viruses are obligate, intracellular pathogens that must manipulate and exploit host molecular mechanisms to prosper in the hostile cellular environment. Here we review the strategies used by viruses ...to evade the immunity controlled by 21- to 26-nt small RNAs. Viral suppressors of RNA silencing (VSRs) are encoded by genetically diverse viruses infecting plants, invertebrates, and vertebrates. VSRs target key steps in the small RNA pathways by inhibiting small RNA production, sequestering small RNAs, or preventing short- and long-distance spread of RNA silencing. However, although VSRs are required for infection, explicit data demonstrating a role of silencing suppression in virus infection are available only for a few VSRs. A subset of VSRs bind double-stranded RNA, but a distinct protein fold is revealed for each of the four VSRs examined. We propose that VSR families are evolved independently as a viral adaptation to immunity. Unresolved issues on the role of RNA silencing in virus-host interactions are highlighted.
A multicomponent metallic glass (MG) with highly efficient and anomalous durability for catalyzing water splitting is reported. The outstanding performance of the MG catalyst contributed by ...self‐optimized active sites originates from the intrinsic chemical heterogeneity and selective dealloying on the disordered surface; thus, a new mechanism for improving the durability of catalysts is uncovered.
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