Development of a glass-based imaging phantom to model the optical properties of human tissue.

The fabrication of a stable, reproducible optical imaging phantom is critical to the assessment and optimization of optical imaging systems. We demonstrate the use of an alternative material, glass, for the development of tissue-mimicking phantoms. The glass matrix was doped with nickel ions to approximate the absorption of hemoglobin. Scattering levels representative of human tissue were induced in the glass matrix through controlled crystallization at elevated temperatures. We show that this type of glass is a viable material for creating tissue-mimicking optical phantoms by providing controlled levels of scattering and absorption with excellent optical homogeneity, long-term stability and reproducibility.

A metal-free carbon catalyst for oxidative dehydrogenation of aryl cyclohexenes to produce biaryl compounds.

A metal-free route based on a carbon catalyst to synthesize biphenyls through oxidative dehydrogenation (ODH) of phenyl cyclohexene has been investigated. Among the samples examined, an air-oxidized active carbon exhibits the best activity with a 9.1 × 10-2 h-1 rate constant, yielding 74% biphenyl in 28 h at 140 °C under five bar O2 in anisole. The apparent activation energy is measured as 54.5 kJ⋅mol-1. The extended reaction scope, consisting of 15 differently substituted phenyl cyclohexenes, shows the wide applicability of the proposed method. The catalyst's good recyclability over six runs suggests this ODH method as a promising route to access the biaryl compounds. In addition, the reaction mechanism is investigated with a combination of X-ray photoelectron spectroscopy, functional group blocking, and model compounds of carbon catalysts and is proposed to be based on the redox cycle of the quinoidic groups on the carbon surface. Additional experiments prove that the addition of the catalytic amount of acid (methanesulfonic acid) accelerates the reaction. In addition, Hammett plot examination suggests the formation of a carbonium intermediate, and its possible structure is outlined.

WiTransformer: A Novel Robust Gesture Recognition Sensing Model with WiFi.

The past decade has demonstrated the potential of human activity recognition (HAR) with WiFi signals owing to non-invasiveness and ubiquity. Previous research has largely concentrated on enhancing precision through sophisticated models. However, the complexity of recognition tasks has been largely neglected. Thus, the performance of the HAR system is markedly diminished when tasked with increasing complexities, such as a larger classification number, the confusion of similar actions, and signal distortion To address this issue, we eliminated conventional convolutional and recurrent backbones and proposed WiTransformer, a novel tactic based on pure Transformers. Nevertheless, Transformer-like models are typically suited to large-scale datasets as pretraining models, according to the experience of the Vision Transformer. Therefore, we adopted the Body-coordinate Velocity Profile, a cross-domain WiFi signal feature derived from the channel state information, to reduce the threshold of the Transformers. Based on this, we propose two modified transformer architectures, united spatiotemporal Transformer (UST) and separated spatiotemporal Transformer (SST) to realize WiFi-based human gesture recognition models with task robustness. SST intuitively extracts spatial and temporal data features using two encoders, respectively. By contrast, UST can extract the same three-dimensional features with only a one-dimensional encoder, owing to its well-designed structure. We evaluated SST and UST on four designed task datasets (TDSs) with varying task complexities. The experimental results demonstrate that UST has achieved recognition accuracy of 86.16% on the most complex task dataset TDSs-22, outperforming the other popular backbones. Simultaneously, the accuracy decreases by at most 3.18% when the task complexity increases from TDSs-6 to TDSs-22, which is 0.14-0.2 times that of others. However, as predicted and analyzed, SST fails because of excessive lack of inductive bias and the limited scale of the training data.

UAV's Status Is Worth Considering: A Fusion Representations Matching Method for Geo-Localization.

Visual geo-localization plays a crucial role in positioning and navigation for unmanned aerial vehicles, whose goal is to match the same geographic target from different views. This is a challenging task due to the drastic variations in different viewpoints and appearances. Previous methods have been focused on mining features inside the images. However, they underestimated the influence of external elements and the interaction of various representations. Inspired by multimodal and bilinear pooling, we proposed a pioneering feature fusion network (MBF) to address these inherent differences between drone and satellite views. We observe that UAV's status, such as flight height, leads to changes in the size of image field of view. In addition, local parts of the target scene act a role of importance in extracting discriminative features. Therefore, we present two approaches to exploit those priors. The first module is to add status information to network by transforming them into word embeddings. Note that they concatenate with image embeddings in Transformer block to learn status-aware features. Then, global and local part feature maps from the same viewpoint are correlated and reinforced by hierarchical bilinear pooling (HBP) to improve the robustness of feature representation. By the above approaches, we achieve more discriminative deep representations facilitating the geo-localization more effectively. Our experiments on existing benchmark datasets show significant performance boosting, reaching the new state-of-the-art result. Remarkably, the recall@1 accuracy achieves 89.05% in drone localization task and 93.15% in drone navigation task in University-1652, and shows strong robustness at different flight heights in the SUES-200 dataset.

Phthalide metabolites produced by mangrove endophytic fungus Pestalotiopsis sp. SAS4.

Two new phthalide derivatives (1-2) and four known phthalide compounds (3-6) were purified from the culture of a mangrove endophytic fungus Pestalotiopsis sp. SAS4. Their chemical structures were established by analyses of 1D and 2D nuclear magnetic resonance (NMR) and high resolution mass spectrometry (HR-MS) spectroscopic data. All of these compounds were evaluated in vitro for antibacterial, cytotoxicity, and resistance to hypoxic-ischemic injury activities.

Abrupt degenerately-doped silicon nanowire tunnel junctions.

We have confirmed the presence of narrow, degenerately-doped axial silicon nanowire (SiNW) p-n junctions via off-axis electron holography (EH). SiNWs were grown via the vapor-solid-liquid (VLS) mechanism using gold (Au) as the catalyst, silane (SiH4), diborane (B2H6) and phosphine (PH3) as the precursors, and hydrochloric acid (HCl) to stabilize the growth. Two types of growth were carried out, and in each case we explored growth with both n/p and p/n sequences. In the first type, we abruptly switched the dopant precursors at the desired junction location, and in the second type we slowed the growth rate at the junction to allow the dopants to readily leave the Au catalyst. We demonstrate degenerately-doped p/n and n/p nanowire segments with abrupt potential profiles of 1.02 ± 0.02 and 0.86 ± 0.3 V, and depletion region widths as narrow as 10 ± 1 nm via EH. Low temperature current-voltage measurements show an asymmetric curvature in the forward direction that resemble planar gold-doped tunnel junctions, where the tunneling current is hidden by a large excess current. The results presented herein show that the direct VLS growth of degenerately-doped axial SiNW p-n junctions is feasible, an essential step in the fabrication of more complex SiNW-based devices for electronics and solar energy.

Total Synthesis of Dysoxylactam A.

The total synthesis of a potent multi-drug-resistant reverser, dysoxylacatam A (1), was achieved in a highly efficient and stereocontrolled fashion. The highlights of the strategy enlisted an iterative combination of lithiation-borylation tactics including Aggarwal homologation and Matteson homologation, Brown crotylation, Krische allylation, and ring-closing metathesis to forge the macrocycle.

Total Synthesis of Psymberin (Irciniastatin A).

A convergent, stereocontrolled total synthesis of psymberin, an architecturally complex marine antitumor agent, has been achieved in 27 steps from the known aldehyde 8. Highlights of this synthesis include a novel and efficient transannular Michael addition/lactone reduction sequence to construct the highly substituted 2,6- trans-tetrahydropyran, a diastereoselective IBr-induced iodocarbonate cyclization to introduce the C17 stereogenic center, and a Diels-Alder/aromatization reaction to install the highly substituted aromatic ring.

Axial EBIC oscillations at core/shell GaAs/Fe nanowire contacts.

Electron beam induced current (EBIC) measurements were carried out in situ in the scanning electron microscope on free-standing GaAs/Fe core-shell nanowires (NWs), isolated from the GaAs substrate via a layer of aluminum oxide. The excess current as a function of the electron beam energy, position on the NW, and scan direction were collected, together with energy dispersive x-ray spectroscopy. A model that included the effects of beam energy and Fe thickness predicted an average collection efficiency of 60%. Small spatial oscillations in the EBIC current were observed, that correlated with the average Fe grain size (30 nm). These oscillations likely originated from lateral variations in the interfacial oxide thickness, affecting the resistance, barrier potentials, and density of minority carrier recombination traps.

Aligned cuboid iron nanoparticles by epitaxial electrodeposition.

Aligned, individual iron square cuboid nanoparticles have been achieved by taking advantage of epitaxial, three-dimensional-island growth on GaAs(001) during electrodeposition at low deposition rates. The nanoparticles exhibit lateral dimensions between 10 and 80 nm and heights below 40 nm. Surface {100} facets predominate with a thin crystalline oxide shell that protects the nanoparticles during prolonged storage in air. The single crystallinity of the iron in combination with structural alignment leads to an in-plane magnetic anisotropy. These immobilized, oriented, and stable nanoparticles are promising for applications in nanoelectronic, sensor, and data storage technologies, as well as for the detailed analysis of the effect of shape and size on magnetism at the nanoscale.

Transcriptome Profiling of Tomato Fruit Development Reveals Transcription Factors Associated with Ascorbic Acid, Carotenoid and Flavonoid Biosynthesis.

Tomato (Solanum lycopersicum) serves as a research model for fruit development; however, while it is an important dietary source of antioxidant nutrients, the transcriptional regulation of genes that determine nutrient levels remains poorly understood. Here, the transcriptomes of fruit at seven developmental stages (7, 14, 21, 28, 35, 42 and 49 days after flowering) from two tomato cultivars (Ailsa Craig and HG6-61) were evaluated using the Illumina sequencing platform. A total of 26,397 genes, which were expressed in at least one developmental stage, were detected in the two cultivars, and the expression patterns of those genes could be divided into 20 groups using a K-mean cluster analysis. Gene Ontology term enrichment analysis indicated that genes involved in RNA regulation, secondary metabolism, hormone metabolism and cell wall metabolism were the most highly differentially expressed genes during fruit development and ripening. A co-expression analysis revealed several transcription factors whose expression patterns correlated with those of genes associated with ascorbic acid, carotenoid and flavonoid biosynthesis. This transcriptional correlation was confirmed by agroinfiltration mediated transient expression, which showed that most of the enzymatic genes in the ascorbic acid biosynthesis were regulated by the overexpression of each of the three transcription factors that were tested. The metabolic dynamics of ascorbic acid, carotenoid and flavonoid were investigated during fruit development and ripening, and some selected transcription factors showed transcriptional correlation with the accumulation of ascorbic acid, carotenoid and flavonoid. This transcriptome study provides insight into the regulatory mechanism of fruit development and presents candidate transcription factors involved in secondary metabolism.

[Studies on anti-tumor and enhancing immunity activity of toad coat].

OBJECTIVE: To study the anti-tumor and immunity activity of toad coat (Chantui), which is a new officinal part of Bufo bufo gargarizans. METHOD: The tumor weight of S180, H22, Lewis lung cancer cell inoculated in mice were compared between the groups of mice, fed with toad coat, and those which were not (control group). The average longevity of the mice with HCA fed with toad coat was also compared with the control group. The T lymphocyte transformation and NK cell killing activity were tested and compared with the control group. The condition of the mice which were fed with great dosage of Chantui (16 g x kg(-1) x d(-1)) was observed. RESULT: The tumor weight was remarkably reduced in the groups which were fed with toad coat compared with the control group. Tests show that toad coat can raise the activity of both T lymphocyte and NK cell. There was no obvious side-effect when the mice were fed with great dosage of toad coat. CONCLUSION: The results show that toad coat has a strong inhibitory activity against tumors inoculated in mice and a strong enhancement of immune activity, so it could be viewed as a new valuable safe medicinal source.