Temperature sensing using junctions between mobile ions and mobile electrons.

Sensing technology is under intense development to enable the Internet of everything and everyone in new and useful ways. Here we demonstrate a method of stretchable and self-powered temperature sensing. The basic sensing element consists of three layers: an electrolyte, a dielectric, and an electrode. The electrolyte/dielectric interface accumulates ions, and the dielectric/electrode interface accumulates electrons (in either excess or deficiency). The ions and electrons at the two interfaces are usually not charge-neutral, and this charge imbalance sets up an ionic cloud in the electrolyte. The design functions as a charged temperature-sensitive capacitor. When temperature changes, the ionic cloud changes thickness, and the electrode changes open-circuit voltage. We demonstrate high sensitivity (∼1 mV/K) and fast response (∼10 ms). Such temperature sensors can be made small, stable, and transparent. Depending on the arrangement of the electrolyte, dielectric, and electrode, we develop four designs for the temperature sensor. In addition, the temperature sensor has good linearity in the range of tens of Kelvin. We further show that the temperature sensors can be integrated into stretchable electronics and soft robots.

Recent Progress in Site-Selective Modification of Peptides and Proteins Using Macrocycles.

Peptides and proteins undergo crucial modifications to alter their physicochemical properties to expand their applications in diverse fields. Various techniques, such as unnatural amino acid incorporation, enzyme catalysis, and chemoselective methods, have been employed for site-selective peptide and protein modification. While traditional methods remain valuable, advancement in host-guest chemistry introduces innovative and promising approaches for the selective modification of peptides and proteins. Macrocycles exhibit robust binding affinities, particularly with natural amino acids, which facilitates their use in selectively binding to specific sequences. This distinctive property endows macrocycles with the potential for modification of target peptides and proteins. This review provides a comprehensive overview of strategies utilizing macrocycles for the selective modification of peptides and proteins. These strategies unlock new possibilities for constructing antibody-drug conjugates and stabilizing volatile medications.

SN2 Reaction at the Amide Nitrogen Center Enables Hydrazide Synthesis.

Nucleophilic substitutions are fundamentally important transformations in synthetic organic chemistry. Despite the substantial advances in bimolecular nucleophilic substitutions (SN2) at saturated carbon centers, analogous SN2 reaction at the amide nitrogen atom remains extremely limited. Here we report an SN2 substitution method at the amide nitrogen atom with amine nucleophiles for nitrogen-nitrogen (N-N) bond formation that leads to a novel strategy toward biologically and medicinally important hydrazide derivatives. We found the use of sulfonate-leaving groups at the amide nitrogen atom played a pivotal role in the reaction. This new N-N coupling reaction allows the use of O-tosyl hydroxamates as electrophiles and readily available amines, including acyclic aliphatic amines and saturated N-heterocycles as nucleophiles. The reaction features mild conditions, broad substrate scope (>80 examples), excellent functional group tolerability, and scalability. The method is applicable to late-stage modification of various approved drug molecules, thus enabling complex hydrazide scaffold synthesis.

Concise Synthesis of (-)-GA18 Methyl Ester.

Gibberellins (GAs) are important plant hormones, but some of their family members are in extremely limited natural supply including GA18. Herein, we report a concise synthesis of (-)-GA18 methyl ester, a member of the C20 gibberellins, from commercially available and cheap andrographolide. Our synthesis features an intramolecular ene reaction to form the C ring, an oxidative cleavage followed by aldol condensation to realize a ring contraction and form the challenging trans-hydrindane (AB ring), and a photochemical [2+2] cycloaddition accompanied by a subsequent SmI2-mediated skeletal rearrangement to construct the methylenebicyclo[3.2.1]octanol moiety (CD ring).

Bioinformatics screening of biomarkers related to liver cancer.

BACKGROUND: Liver cancer is a common malignant tumor in China, with high mortality. Its occurrence and development were thoroughly studied by high-throughput expression microarray, which produced abundant data on gene expression, mRNA quantification and the clinical data of liver cancer. However, the hub genes, which can be served as biomarkers for diagnosis and treatment of early liver cancer, are not well screened. RESULTS: Here we present a new method for getting 6 key genes, aiming to diagnose and treat the early liver cancer. We firstly analyzed the different expression microarrays based on TCGA database, and a total of 1564 differentially expressed genes were obtained, of which 1400 were up-regulated and 164 were down-regulated. Furthermore, these differentially expressed genes were studied by using GO and KEGG enrichment analysis, a PPI network was constructed based on the STRING database, and 15 hub genes were obtained. Finally, 15 hub genes were verified by applying the survival analysis method on Oncomine database, and 6 key genes were ultimately identified, including PLK1, CDC20, CCNB2, BUB1, MAD2L1 and CCNA2. The robustness analysis of four independent data sets verifies the accuracy of the key gene's classification of the data set. CONCLUSIONS: Although there are complicated differences between cancer and normal cells in gene functions, cancer cells could be differentiated in case that a group of special genes expresses abnormally. Here we presented a new method to identify the 6 key genes for diagnosis and treatment of early liver cancer, and these key genes can help us understand the pathogenesis of liver cancer more deeply.

Electrochemical breakdown in hydrogel ionotronic devices.

In recent years, hydrogel, as a stretchable, transparent, ionic conductor, has attracted considerable attention and its integration with various materials has enabled new functions: hydrogel ionotronics. These hybrid systems rely on both mobile ions and mobile electrons. However, coupling of ions and electrons brings a new challenge: electrochemical breakdown. Here, we study the breakdown behaviors of a typical ionotronic system-a hydrogel-elastomer device at high DC voltage, which consists of three elements: hydrogel, dielectric elastomer, and metal. We develop a phase diagram of the possible failure modes through theory and experiment, and find a new failure mode, electrochemical breakdown, caused by ion-electron exchange at the metal-hydrogel interface. Our experiments show that the breakdown voltage of the dielectric elastomer decreases when the capacitance of the electrical double layer formed at the metal-hydrogel interface is below a certain value. It is found that the failure mode and its transition are determined by three material properties: the electrical breakdown strength of the dielectric elastomer, the capacitance of the metal-hydrogel interface per unit area, and the electrochemical window of the hydrogel electrolyte. These findings will guide the characterization and improvement of the reliability of hydrogel ionotronic devices.

Paternal fenvalerate exposure transgenerationally impairs cognition and hippocampus in female offspring.

The impairments of maternal fenvalerate exposure have been well documented in previous study, but little was known about the effects of paternal fenvalerate exposure. The current study aimed to assess the effects of paternal fenvalerate exposure on spatial cognition and hippocampus across generations. Adult male mice (F0) were orally administered with fenvalerate (0, 2 or 20 mg/kg) for 5 weeks. F0 males were mated with untreated-females to generate F1 generation. F1 males were mated with F1 control females to generate F2 generation. For F1 and F2 adult offspring, spatial learning and memory were detected by Morris water maze. Results showed that spatial learning and memory were impaired in F1 females but not F1 males derived from F0 males exposed to 20 mg/kg FEN. Furthermore, significant impairment of spatial learning and memory were found in F2 females but not F2 males derived from F0 males exposed to 20 mg/kg FEN. As expected, histopathology showed that neural density in hippocampal CA3 region was reduced in F1 and F2 females but not F1 and F2 males derived from F0 males exposed to 20 mg/kg FEN. Mechanistically, hippocampal thyroid hormone receptor alpha1 (TRα1) was down-regulated in F1 and F2 females derived from F0 males exposed to 20 mg/kg FEN. Correspondingly, hippocampal brain-derived neurotrophic factor, tropomyosin receptor kinase B and p75 neurotrophin receptor, three downstream genes of TR signaling, were down-regulated in F1 and F2 females. Taken together, the present study firstly found that paternal fenvalerate exposure transgenerationally impaired spatial cognition in a gender-dependent manner. Hippocampal TR signaling may, at least partially, contribute to the process of cognitive impairment induced by paternal fenvalerate exposure. Further exploration in the mode of action of fenvalerate is critically important to promote human health and environmental safety.

Stretchable Electrets: Nanoparticle-Elastomer Composites.

Manipulating charges is fundamental to numerous systems, and this ability is achieved through materials of diverse characteristics. Electrets are dielectrics that trap charges or dipoles. Applications include electrophotography, microphones, air filters, and energy harvesters. To trap charges or dipoles for a long time, electrets are commonly made of hard dielectrics. Stretchable dielectrics are short-lived electrets. The two properties, longevity and stretchability, conflict; existing electrets struggle to attain both. This work describes an approach to developing stretchable electrets. Nanoparticles of a hard electret are immobilized in a matrix of dielectric elastomer. The composite divides the labor of two functions: the particles trap charges with longevity, and the matrix enables stretchability. The design considerably broadens the choice of materials to enable stretchable electrets. Silica nanoparticles in the polydimethylsiloxane elastomer achieve a charge density ∼ 4 × 10-5 C m-2 and a lifetime beyond 60 days. Long-lived, stretchable electrets open extensive opportunities.

Flow Chemistry-Enabled Divergent and Enantioselective Total Syntheses of Massarinolin†A, Purpurolides†B, D, E, 2,3-Deoxypurpurolide†C, and Structural Revision of Massarinolin†A.

Massarinolin A and purpurolides are bioactive bergamotane sesquiterpenes condensed with a variety of synthetically challenging ring systems: a bicyclo[3.1.1]heptane, an oxaspiro[3.4]octane, and a dioxaspiro[4.4]nonane (oxaspirolactone). Herein, we report the first enantioselective total syntheses of massarinolin A, purpurolides B, D, E, and 2,3-deoxypurpurolide C. Our synthesis and computational analysis also led to a structural revision of massarinolin A. The divergent approach features an enantioselective organocatalyzed Diels-Alder reaction to install the first stereogenic center in high ee, a scalable flow photochemical Wolff rearrangement to build the key bicyclo[3.1.1]heptane, a furan oxidative cyclization to form the oxaspirolactone, a late-stage allylic C-H oxidation, and a Myers' NBSH-promoted sigmatropic elimination to install the exo methylene group of massarinolin A.

Fatigue-free, superstretchable, transparent, and biocompatible metal electrodes.

Next-generation flexible electronics require highly stretchable and transparent electrodes. Few electronic conductors are both transparent and stretchable, and even fewer can be cyclically stretched to a large strain without causing fatigue. Fatigue, which is often an issue of strained materials causing failure at low strain levels of cyclic loading, is detrimental to materials under repeated loads in practical applications. Here we show that optimizing topology and/or tuning adhesion of metal nanomeshes can significantly improve stretchability and eliminate strain fatigue. The ligaments in an Au nanomesh on a slippery substrate can locally shift to relax stress upon stretching and return to the original configuration when stress is removed. The Au nanomesh keeps a low sheet resistance and high transparency, comparable to those of strain-free indium tin oxide films, when the nanomesh is stretched to a strain of 300%, or shows no fatigue after 50,000 stretches to a strain up to 150%. Moreover, the Au nanomesh is biocompatible and penetrable to biomacromolecules in fluid. The superstretchable transparent conductors are highly desirable for stretchable photoelectronics, electronic skins, and implantable electronics.

Enantioselective Total Synthesis of (+)-Plumisclerin†A.

The first and enantioselective total synthesis of (+)-plumisclerin A, a novel unique complex cytotoxic marine diterpenoid, has been accomplished. Around the central cyclopentane anchorage, a sequential ring-formation protocol was adopted to generate the characteristic tricycle[4.3.1.01,5 ]decane and trans-fused dihyrdopyran moiety. Scalable enantioselective LaIII -catalyzed Michael reaction, palladium(0)-catalyzed carbonylation and SmI2 -mediated radical conjugate addition were successfully applied in the synthesis, affording multiple grams of the complex and rigid B/C/D-ring system having six continuous stereogenic centers and two all-carbon quaternary centers. The trans-fused dihyrdopyran moiety with an exo side-chain was furnished in final stage through sequential redox transformations from a lactone precursor, which overcome the largish steric strain of the dense multiring system. The reported total synthesis also confirms the absolute chemistries of natural (+)-plumisclerin A.

Antifungal agents against Aspergillus niger for rearing rice leaffolder larvae (Lepidoptera: Pyralidae) on artificial diet.

Mold contamination is an important issue in insect mass rearing. Frequently used antifungal agents such as sorbic acid and methylparaben have negative impact on many lepidopteran larvae, which might be one of the reasons for the difficulty in rearing rice leaffolder, Cnaphalocrocis medinalis (Güenée). In this study, 19 antifungal agents, including 7 food preservatives, 6 antifungal drugs, and 6 agricultural fungicides, were screened for their inhibitory activities on Aspergillus niger in diets. The results demonstrated that most of the tested chemicals are unsuitable as mold inhibitors in the diets of the rice leaffolder, and the rice leaffolder neonate is sensitive to sorbic acid and methylparaben. These two mold inhibitors at commonly used concentrations were shown to impact the survival of rice leaffolder larvae fed on artificial diets. Among the tested mold inhibitors, natamycin was the safest for the rice leaffolder larvae. Much higher larva survival was observed for the larvae fed on diets containing natamycin as an antifungal agent (59 and 72% at 200 and 400 ppm, respectively). Two agricultural fungicides, tebuconazole and azoxystrobin, are also potent as mold inhibitors when used in insect diets. The mixed use of natamycin and sorbic acid, or methylparaben, and the mixed use of sorbic acid and azoxystrobin resulted in significantly higher larva survival than sorbic acid + methylparaben. Natamycin + azoxystrobin and sorbic acid + tebuconazole resulted in larva survival similar to that of sorbic acid + methylparaben. The ternary combination of natamycin, sorbic acid, and methylparaben was the best combination for the rearing of rice leaffolder.

Resistance in Cnaphalocrocis medinalis (Lepidoptera: Pyralidae) to new chemistry insecticides.

The control of rice leaffolder, Cnaphalocrocis medinalis (Guenée), depended mainly on the insecticide application in China for a long time, and the resistance development impacted the effects of insecticide application. In this study, 13 conventional and new chemistry insecticides were assayed for the toxicities to the larvae of rice leaffolder collected from Nanning, Changsha, and Nanjing, China, with rice seedling dip method during 2011-2013. Among the tested chemicals, macrolide insecticides spinetoram, spinosad, abamectin, and emanectin benzoate have the highest toxicities, whereas monosultap and Bt have the least toxicities to this insect. Comparing with the baseline data established in 2010, the susceptibilities of rice leaffolder to chlorantraniliprole, metaflumizone, and tebufenozide are declining simultaneously and gradually in the three regions from 2011 to 2013, and C. medinalis are becoming resistance to chlorantraniliprole, metaflumizone, and tebufenozide. The synchronous decreases of susceptibility in three geographic populations were not observed for macrolide insecticides, indoxacarb, chlorpyrifos, monosultap, and Bt. The synchronous insecticide susceptibility declines in field populations of the migratory insect collected from different areas indicated resistance evolution, and the sequence application patterns of different insecticides should be scheduled to delay the further development of resistance along the migratory pathway of the rice leaffolder in China.

Inhibiting the Aggregation of Aß by Natural Product Molecules.

The abnormal aggregation of Aß has been considered one of the primary causative factors for Alzheimer's disease. Diverse molecular entities have been developed to mitigate the formation of toxic Aß aggregates within the brain by inhibiting Aß aggregation. Recognizing that many FDA-approved drugs are derived from natural products, we present a summary of recent discoveries involving natural product molecules with inhibitory effects on Aß aggregation. By consolidating these findings, our review offers researchers a concise overview of the latest advancements in natural product-based interventions for Alzheimer's disease.

Ultra-High Frequency Self-Focusing Ultrasonic Sensors With Half-Concave Geometry for Visualization of Mouse Brain Atrophy.

Ultra-high frequency (>100 MHz) acoustic waves feature biocompatibility and high sensitivity and allow biomedical imaging and acoustic tweezers. Primarily, excellent spatial resolution and broad bandwidth at ultra-high frequency is the goal for pathological research and cell selection at the cellular level. Here, we propose an efficient approach to visualize mouse brain atrophy by self-focused ultrasonic sensors at ultra-high frequency with ultra-broad bandwidth. The numerical models of geometry and theoretically predicted acoustic parameters for half-concave piezoelectric elements are calculated by the differential method, which agrees with measured results (lateral resolution: 24 µm, and bandwidth: 115% at -6 dB). Compared with the brain slices of 2-month-old mouse, the atrophy visualization of the 6-month-old mouse brain was realized by C-mode imaging with an acoustic microscopy system, which is a potential prospect for diagnosis and treatment of Alzheimer's disease (AD) combined with neuroscience. Meanwhile, the acoustic properties of the brain slices were quantitatively measured by the acoustic microscopy. These encouraging results demonstrate the promising application for high-resolution imaging in vitro biological tissue with ultra-high frequency self-focusing ultrasonic sensors.

0.36BiScO3-0.64PbTiO3/Epoxy 1-3-2 High- Temperature Composite Ultrasonic Transducer for Nondestructive Testing Applications.

The development of high-temperature nondestructive testing (NDT) requires ultrasonic transducers with good temperature resistance and high sensitivity for improved detection efficiency. Piezoelectric composite can improve the performance of transducers because of its high electromechanical coupling coefficient and adjustable acoustic impedance. In this study, 1-3-2 composites and 1-3-2 high-temperature composite ultrasonic transducers (HTCUTs) based on 0.36BiScO3-0.64PbTiO3 (BSPT), which is preferred piezoelectric materials at 200 ° C- 300 ° C, and high-temperature epoxy with a center frequency of 6 MHz were designed and fabricated. From 25 ° C to 250 ° C, 1-3-2 composites show a higher electromechanical coupling coefficient kt especially at high temperatures (~0.53 at 25 ° C and ~0.64 at 250 ° C) than monolithic BSPT (~0.5). The signal of the pulse-echo response of 1-3-2 HTCUTs is distinguishable up to 250 ° C and remains stable ( [Formula: see text] mV) below 150 ° C, exhibiting higher sensitivity (improved by 7 dB) than that of monolithic BSPT high-temperature ultrasonic transducers (HTUTs). Bandwidth has been greatly enhanced especially at high temperatures (~103% at 250 ° C) compared with that of monolithic BSPT HTUTs (~30% at 250 ° C). To verify the excellent performance, B-mode scanning imaging measurement of a stepped steel block and defect location detection of a steel block was performed, showing the potential for high-temperature NDT applications.

Design of Bombyx mori (B. mori) Silk Fibroin Microspheres for Developing Biosafe Sunscreen.

Sunscreens play a crucial role in protecting the skin from ultraviolet (UV) damage. However, present commercial sunscreens have a tendency to generate free radicals in the UV window, resulting in serious inflammatory responses and health problems. In this study, we demonstrate that silk fibroin microspheres (SFMPs) assembled from regenerated silk fibroin (SF) could scavenge free radicals while preventing UV irradiation and thus present a promising sunscreen. The SFMP reflected more UV light than SF and presented a higher stability than that of organic commercial sunscreens. In vitro analysis proved that SFMP could more efficiently scavenge the hydroxy radical and reduce the intracellular reactive oxygen than titanium dioxide (TiO2). In vivo experiments exhibited that SFMP provided stronger skin protection against UV irradiation than commercial sunscreens and TiO2. Furthermore, SFMP treatment significantly inhibited the skin inflammatory response. This work suggests that the SFMP has great potential to be developed into a biosafe sunscreen.

Evaluation of resources and environmental carrying capacity of marine ranching in China: An integrated life cycle assessment-emergy analysis.

Resources and environmental carrying capacity (RECC) describes the ability of a system to achieve healthy and sustainable development. Various marine ranching enterprises have emerged in China in recent years, which have aroused concern and debate about the RECC of marine ranching systems. By taking the environmental impact calculated by life cycle assessment (LCA) into consideration in emergy analysis (EA), this study evaluated the comprehensive RECC performance of the whole system and each stage of a marine ranching system in China. The resource use efficiency (RUE) and system carrying ratio (SCR) of the system were reasonably good. However, its environmental loading ratio (ELR), emergy yield ratio (EYR), and emergy sustainability index (ESI) were unsatisfactory. First, the nonrenewable resources dominated the emergy input. Second, the emergy input from the purchased resources was much greater than that of local resources. Third, the potential environmental impact mainly came from the construction stage. Fourth, serious overload of RECC was observed in the maintenance stage. The results indicate that the system is efficient, and its RECC is in a safe state, but the system has deficiencies in environmental protection and the exploitation and utilization of local resources. The proposed analysis framework helps us comprehensively understand the marine ranching RECC performance and provides a research paradigm reference for the sustainability analysis of other complex eco-economic systems.

Total Syntheses of Phleghenrines A and C.

Herein, we report the total syntheses of phleghenrines A and C from commercially available starting materials in 7 and 8 steps, respectively. Notable steps include an inverse electron-demand Diels-Alder reaction between a masked o-benzoquinone and a N-protected enamine to prepare one key intermediate with a bicyclo[2.2.2]octenone core, a Büchner-Curtius-Schlotterbeck one-carbon insertion to expand the bicyclo[2.2.2]octenone to a bicyclo[3.2.2]nonenone, and Trauner's modified 2-pyridone synthesis to install the 2-pyridone moiety.

Fine-grained weed recognition using Swin Transformer and two-stage transfer learning.

Weeding is very critical for agriculture due to its importance for reducing crop yield loss. Accurate recognition of weed species is one of the major challenges for achieving automatic and precise weeding. To improve the recognition performance of weeds and crops with similar visual characteristics, a fine-grained weed recognition method based on Swin Transformer and two-stage transfer learning is proposed in this study. First, the Swin Transformer network is introduced to learn the discriminative features that can distinguish subtle differences between visually similar weeds and crops. Second, a contrastive loss is applied to further enlarge the feature differences between different categories of weeds and crops. Finally, a two-stage transfer learning strategy is proposed to address the problem of insufficient training data and improve the accuracy of weed recognition. To evaluate the effectiveness of the proposed method, we constructed a private weed dataset (MWFI) with maize seedling and seven species of associated weeds that are collected in the farmland environment. The experimental results on this dataset show that the proposed method achieved the recognition accuracy, precision, recall, and F1 score of 99.18%, 99.33%, 99.11%, and 99.22%, respectively, which are superior to the performance of the state-of-the-art convolutional neural network (CNN)-based architectures including VGG-16, ResNet-50, DenseNet-121, SE-ResNet-50, and EfficientNetV2. Additionally, evaluation results on the public DeepWeeds dataset further demonstrate the effectiveness of the proposed method. This study can provide a reference for the design of automatic weed recognition systems.