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We prepared a double-crystal LiTaO3 (LT) electro-optic (EO) Q-switch and investigated its overall Q-switching performances. The LT EO Q-switch is fabricated from two x-cut LT crystals to utilize the maximum effective EO coefficient. The static and dynamic quarter-wave voltage were measured to be 1200 V and 950 V respectively, which are both considerably lower than those of other commercial EO Q-switches. Besides, the LT Q-switch can operate at a wide temperature range with high temperature stability. The dynamic-to-static ratios at sub-freezing temperatures were up to 80 percent of that at room temperature. Furthermore, the piezoelectric ringing in the LT Q-switch was found to be comparable to that of RTP Q-switches, and it had been successfully operated at a repetition rate of 1 kHz with stable Q-switched laser output. The only disadvantage is the low extinction ratio which is mainly caused by the optical inhomogeneity and can be improved by improving the optical quality of LT crystals. The double-crystal LT EO Q-switches are particularly attractive for Q-switched lasers because of their excellent comprehensive performances. [ABSTRACT FROM AUTHOR]

Brevetoxins (PbTxs) are very potent marine neurotoxins that can cause an illness clinically described as neurologic shellfish poisoning (NSP). These toxins are cyclic polyether in chemistry and have increased their geographical distribution in the past 2 decades. However, the ethical problems as well as technical difficulties associated with currently employed analysis methods for marine toxins have spurred the quest for suitable alternatives to be applied in a regulatory monitoring regime. In this work, we reported the first instance of concurrent aptamer selection of Brevetoxin-1 (PbTx-1) and Brevetoxin-2 (PbTx-2) and constructed a biolayer interferometry (BLI) biosensor utilizing PbTx-1 aptamer as a specific recognition element. Through an in vitro selection process, we have, for the first time, successfully selected DNA aptamers with high affinity and specificity to PbTx-1 and PbTx-2 from a vast pool of random sequences. Among the selected aptamers, aptamer A5 exhibited the strongest binding affinity to PbTx-1, with an equilibrium dissociation constant (KD) of 2.56 μM. Subsequently, we optimized aptamer A5 by truncation to obtain the core sequence (A5-S3). Further refinement was achieved through mutations based on the predictions of a QGRS mapper, resulting in aptamer A5-S3G, which showed a significant increase in the KD value by approximately 100-fold. Utilizing aptamer A5-S3G, we fabricated a label-free, real-time optical BLI aptasensor for the detection of PbTx-1. This aptasensor displayed a broad detection range from 100 nM to 4000 nM PbTx-1, with a linear range between 100 nM and 2000 nM, and a limit of detection (LOD) as low as 4.5 nM. Importantly, the aptasensor showed no cross-reactivity to PbTx-2 or other marine toxins, indicating a high level of specificity for PbTx-1. Moreover, the aptasensor exhibited excellent reproducibility and stability when applied for the detection of PbTx-1 in spiked shellfish samples. We strongly believe that this innovative aptasensor offers a promising alternative to traditional immunological methods for the specific and reliable detection of PbTx-1. [ABSTRACT FROM AUTHOR]

l‐threonine dehydrogenase (Tdh) is an enzyme that links threonine metabolism to epigenetic modifications and mitochondria biogenesis. In vitro studies show that it is critical for the regulation of trimethylation of histone H3 lysine 4 (H3K4me3) levels and cell fate determination of mouse embryonic stem cells (mESCs). However, whether Tdh regulates a developmental process in vivo and, if it does, whether it also primarily regulates H3K4me3 levels in this process as it does in mESCs, remains elusive. Here, we revealed that, in zebrafish hematopoiesis, tdh is preferentially expressed in neutrophils. Knockout of tdh causes a decrease in neutrophil number and slightly suppresses their acute injury‐induced migration, but, unlike the mESCs, the level of H3K4me3 is not evidently reduced in neutrophils sorted from the kidney marrow of adult tdh‐null zebrafish. These phenotypes are dependent on the enzymatic activity of Tdh. Importantly, a soluble supplement of nutrients that are able to fuel the acetyl‐CoA pool, such as pyruvate, glucose and branched‐chain amino acids, is sufficient to rescue the reduction in neutrophils caused by tdh deletion. In summary, our study presents evidence for the functional requirement of Tdh‐mediated threonine metabolism in a developmental process in vivo. It also provides an animal model for investigating the nutritional regulation of myelopoiesis and immune response, as well as a useful tool for high‐throughput drug/nutrition screening. [ABSTRACT FROM AUTHOR]

We analyze the transverse electro-optic (EO) effect in an arbitrary direction in LiNbO3 (LN) and LiTaO3 (LT) crystals based on the Fresnel index ellipsoid theory. A set of analytical formulas for calculating the birefringence in any direction in a crystal of the lowest symmetry is first deduced. The maximum magnitudes of the transverse EO effect appear along the directions that are turned out from the optic axis on the angles θm (φ = 30°, 150° or 270°) or 180°− θm (φ = 90°, 210° or 330°), the angles θm of congruent LN and LT crystals are 36° and 59.5°, respectively. For experimental verification, the (yzw)θm cut congruent LN and LT crystals were prepared. The half-wave voltage (HWV) of the (yzw)36° cut LN crystals is half that of the x-cut LN crystals and is only 30% that of the z-cut LN crystals, and the HWV of the (yzw)59.5° cut LT crystals is 7% higher than that of the x-cut LT crystals, the experimental results agree well with the theoretical analysis. The crystals with the optimized cell geometries are more practical because of the low HWV and lower sensitivity of birefringence to temperature. [ABSTRACT FROM AUTHOR]

Clavatols exhibit a wide range of biological activities due to their diverse structures. A genome mining strategy identified an A5cla cluster from Penicillium sp. MYA5, derived from the Arctic plant Dryas octopetala, is responsible for clavatol biosynthesis. Seven clavatols, including one new clavatol derivate named penicophenone F (1) and six known clavatols (2–7), were isolated from Penicillium sp. MYA5 using a transcriptome mining strategy. These structures were elucidated by comprehensive spectroscopic analysis. Antibacterial, aldose reductase inhibition, and siderophore-producing ability assays were conducted on compounds 1–7. Compounds 1 and 2 demonstrated inhibitory effects on the ALR2 enzyme with inhibition rates of 75.3% and 71.6% at a concentration of 10 μM, respectively. Compound 6 exhibited antibacterial activity against Staphylococcus aureus and Escherichia coli with MIC values of 4.0 μg/mL and 4.0 μg/mL, respectively. Additionally, compounds 1, 5, and 6 also showed potential iron-binding ability. [ABSTRACT FROM AUTHOR]

Vanadium–titanium ore possesses significant mining and utilization value. The basicity of vanadium–titanium sinter has a direct impact on the formation, location, thickness, permeability, and heat exchange of the cohesive zone in the blast furnace. This paper investigated the influence of increasing the basicity of the sinter on the comprehensive burden's cohesive dripping properties in the blast furnace, while keeping the final slag basicity constant. This study was conducted through cohesive dripping property experiments. The findings indicated that as the sinter basicity in the comprehensive burden structure increased and the corresponding increase in the proportion of pellets occurred, the softening performance of the comprehensive burden improved, the cohesive zone became thinner, the lower edge of the cohesive zone shifted upward, and the softening melting properties became better in general. With an increase in the sinter basicity, the dripping difference pressure of the comprehensive burden decreased, and the dripping rate firstly increased and then decreased. An increase in the sinter basicity of the comprehensive burden structure promoted V reduction, and the V element yield and Cr element yield of the sinter were both increased; the optimal sinter basicity was 2.5, and the corresponding pellet proportion was 42%. [ABSTRACT FROM AUTHOR]

Eight new scalarane sesterterpenes, phyllofenones F–M (1–8), together with two known analogues, carteriofenones B and A (9–10), were isolated from the marine sponge Phyllospongia foliascens collected from the South China Sea. The structures of these compounds were determined based on extensive spectroscopic and quantum chemical calculation analysis. The antibacterial and cytotoxic activity of these compounds was evaluated. Among them, only compounds 4 and 6 displayed weak inhibitory activity against Staphylococcus aureus and Escherichia coli, with MIC values of 16 μg/mL and 8 μg/mL, respectively. Compounds 1–10 exhibited cytotoxic activity against the HeLa, HCT-116, H460, and SW1990 cancer cell lines, with IC50 values ranging from 3.4 to 19.8 μM. [ABSTRACT FROM AUTHOR]

A chemical investigation of the Arctic-derived fungus Eutypella sp. D-1 based on the OSMAC (one strain many compounds) approach resulted in the isolation of five cytosporin polyketides (compounds 1–3 and 11–12) from rice medium and eight cytosporins (compounds 2 and 4–11) from solid defined medium. The structures of the seven new compounds, eutypelleudesmane A (1), cytosporin Y (2), cytosporin Z (3), cytosporin Y1 (4), cytosporin Y2 (5), cytosporin Y3 (6), and cytosporin E1 (7), were elucidated by analyzing their detailed spectroscopic data. Structurally, cytosporin Y1 (4) may be a key intermediate in the biosynthesis of the isolated cytosporins, rather than an end product. Compound 1 contained a unique skeleton formed by the ester linkage of two moieties, cytosporin F (12) and the eudesmane-type sesquiterpene dihydroalanto glycol. Additionally, the occurrence of cyclic carbonate moieties in compounds 6 and 7 was found to be rare in nature. The antibacterial, immunosuppressive, and cytotoxic activities of all compounds derived from Eutypella sp. D-1 were evaluated. Unfortunately, only compounds 3, 6, 8, and 10–11 displayed immunosuppressive activity, with inhibitory rates of 62.9%, 59.5%, 67.8%, 55.8%, and 68.7%, respectively, at a concentration of 5 μg/mL. [ABSTRACT FROM AUTHOR]

DNAzymes have been widely and effectively used for the detection of pathogenic bacteria, which pose a serious public health threat. However, the rapid and cost‐effective detection of such bacteria remains a major challenge. In this study, we successfully selected Vibrio alginolyticus‐specific DNAzymes. The activity of the candidates was assessed via fluorescence intensity and gel electrophoresis. The DNAzyme DT1 had a detection limit of 31 CFU/ml for V. alginolyticus and exhibited high specificity. Graphene oxide (GO) was used to develop a DNAzyme‐based fluorescent sensor for the detection of V. alginolyticus, which significantly improved detection performance and shortened the reaction time as little as 10 s. The proposed method was then validated using crab, shrimp, fish, clam, and oyster samples. This study thus provides a new method for the rapid and sensitive detection of V. alginolyticus. [ABSTRACT FROM AUTHOR]

The enzyme dextranase is widely used in the sugar and food industries, as well as in the medical field. Most land‐derived dextranases are produced by fungi and have the disadvantages of long production cycles, low tolerance to environmental conditions, and low safety. The use of marine bacteria to produce dextranases may overcome these problems. In this study, a dextranase‐producing bacterium was isolated from the Rizhao seacoast of Shandong, China. The bacterium, denoted as PX02, was identified as Cellulosimicrobium sp. and its growing conditions and the production and properties of its dextranase were investigated. The dextranase had a molecular weight of approximately 40 kDa, maximum activity at 40°C and pH 7.5, with a stability range of up to 45°C and pH 7.0–9.0. High‐performance liquid chromatography showed that the dextranase hydrolyzed dextranT20 to isomaltotriose, maltopentaose, and isomaltooligosaccharides. Hydrolysis by dextranase produced excellent antioxidant effects, suggesting its potential use in the health food industry. Investigation of the action of the dextranase on Streptococcus mutans biofilm and scanning electron microscopy showed that it to be effective both for removing and inhibiting the formation of biofilms, suggesting its potential application in the dental industry. [ABSTRACT FROM AUTHOR]

The amino acid response (AAR) and unfolded protein response (UPR) pathways converge on eIF2α phosphorylation, which is catalyzed by Gcn2 and Perk, respectively, under different stresses. This close interconnection makes it difficult to specify different functions of AAR and UPR. Here, we generated a zebrafish model in which loss of threonyl-tRNA synthetase (Tars) induces angiogenesis dependent on Tars aminoacylation activity. Comparative transcriptome analysis of the tars-mutant and wild-type embryos with/without Gcn2- or Perk-inhibition reveals that only Gcn2-mediated AAR is activated in the tars-mutants, whereas Perk functions predominantly in normal development. Mechanistic analysis shows that, while a considerable amount of eIF2α is normally phosphorylated by Perk, the loss of Tars causes an accumulation of uncharged tRNAThr, which in turn activates Gcn2, leading to phosphorylation of an extra amount of eIF2α. The partial switchover of kinases for eIF2α largely overwhelms the functions of Perk in normal development. Interestingly, although inhibition of Gcn2 and Perk in this stress condition both can reduce the eIF2α phosphorylation levels, their functional consequences in the regulation of target genes and in the rescue of the angiogenic phenotypes are dramatically different. Indeed, genetic and pharmacological manipulations of these pathways validate that the Gcn2-mediated AAR, but not the Perk-mediated UPR, is required for tars-deficiency induced angiogenesis. Thus, the interconnected AAR and UPR pathways differentially regulate angiogenesis through selective functions and mutual competitions, reflecting the specificity and efficiency of multiple stress response pathways that evolve integrally to enable an organism to sense/respond precisely to various types of stresses. [ABSTRACT FROM AUTHOR]

Fast timing detector is widely used for its picosecond (ps)-level timing resolution, such as Photek-PMT210 with about 50 ps at single-photon electron (SPE) mode. The time characteristics of these types of fast timing photodetectors include rise time, fall time, and electron transit time (TT) of the output signal. The test results of fast timing detector are affected by the light 7 source, the electronic device board, the data acquisition (DAQ) system, and so on. In this article, some comparative test results will be shown and discussed on the factors affecting the performance of fast timing detector. [ABSTRACT FROM AUTHOR]

Dextranase specifically hydrolyzes dextran and is used to produce functional isomalto-saccharide prebiotics. Moreover, dextranase is used as an additive in mouthwash to remove dental plaque. We cloned and expressed the dextranase gene of the marine bacterium Bacillus aquimaris S5. The length of the BaDex gene was 1788 bp, encoding 573 amino acids. Using bioinformatics to predict and analyze the amino acid sequence of BaDex, we found the isoelectric point and instability coefficient to be 4.55 and 29.22, respectively. The average hydrophilicity (GRAVY) was −0.662. The secondary structure of BaDex consisted of 145 alpha helices, accounting for 25.31% of the protein; 126 extended strands, accounting for 21.99%; and 282 random coils, accounting for 49.21%. The 3D structure of the BaDex protein was predicted and simulated using SWISS-MODEL, and BaDex was classified as a Glycoside Hydrolase Family 66 protein. The optimal temperature and pH for BaDex activity were 40°C and 6.0, respectively. The hydrolysates had excellent antioxidant activity, and 8 U/mL of BaDex could remove 80% of dental plaque in MBRC experiment. This recombinant protein thus has great promise for applications in the food and pharmaceutical industries. [ABSTRACT FROM AUTHOR]

HEPS-BPIX is a silicon pixel detector designed for the future large scientific facility, high-energy photon sources (HEPS) in Beijing, China. It is a high frame rate hybrid pixel detector which works in the single-photon-counting mode. High frame rate leads to much higher readout data bandwidth than former systems, which is also the difficulty of the design. Aiming to test and calibrate the pixel detector, a test system based on the National Instruments single-board RIO 9626 and LabVIEW program environment has been designed. A series of tests has been carried out with X-ray machine as well as on the Beijing Synchrotron Radiation Facility 1W2B beamline. The test results show that the threshold uniformity is better than 60 electrons and the equivalent noise charge is less than 120 electrons. Besides, the required highest frame rate of 1.2 kHz has been realized. This paper will elaborate the test system design and present the latest testing results of the HEPS-BPIX system. [ABSTRACT FROM AUTHOR]

Cu/Ag core-shell composite was synthesized by the replacement-reduction method and was applied to the catalytic field. The specimens were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscope (TEM). The growth mechanism was investigated by the first-principles calculation, including the density of states, Mulliken population, and electronic structures. By comparing the calculation and characterization, it is concluded that the difference in interfacial properties leads to the growth of silver on the copper surface in the Stranski–Krastanow (SK) mode. [ABSTRACT FROM AUTHOR]