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C-H bond activation enables the facile synthesis of new chemicals. While C-H activation in short-chain alkanes has been widely investigated, it remains largely unexplored for long-chain organic molecules. Here, we report light-driven C-H activation in complex organic materials mediated by 2D transition metal dichalcogenides (TMDCs) and the resultant solid-state synthesis of luminescent carbon dots in a spatially-resolved fashion. We unravel the efficient H adsorption and a lowered energy barrier of C-C coupling mediated by 2D TMDCs to promote C-H activation and carbon dots synthesis. Our results shed light on 2D materials for C-H activation in organic compounds for applications in organic chemistry, environmental remediation, and photonic materials.

Optical tweezers have profound importance across fields ranging from manufacturing to biotechnology. However, the requirement of refractive index contrast and high laser power results in potential photon and thermal damage to the trapped objects, such as nanoparticles and biological cells. Optothermal tweezers have been developed to trap particles and biological cells via opto-thermophoresis with much lower laser powers. However, the intense laser heating and stringent requirement of the solution environment prevent their use for general biological applications. Here, we propose hypothermal opto-thermophoretic tweezers (HOTTs) to achieve low-power trapping of diverse colloids and biological cells in their native fluids. HOTTs exploit an environmental cooling strategy to simultaneously enhance the thermophoretic trapping force at sub-ambient temperatures and suppress the thermal damage to target objects. We further apply HOTTs to demonstrate the three-dimensional manipulation of functional plasmonic vesicles for controlled cargo delivery. With their noninvasiveness and versatile capabilities, HOTTs present a promising tool for fundamental studies and practical applications in materials science and biotechnology.

In order to investigate the quality changes in different parts of rice ball during storage at 4 ℃, rice ball was divided into outer, middle and inner parts from outside to inside, and low-field nuclear magic resonance (NMR) spectroscopy, a rice taste analyzer, an X-ray diffractometer, scanning electron microscopy (SEM) and gas chromatography-ion mobility spectrometry (GC-IMS) were used to analyze the physicochemical and microstructural changes of the three parts of rice ball during storage. The results showed that with the increase in storage time, the moisture content of rice ball changed little, but the transverse relaxation time (T2) of each part of rice ball exhibited an overall downward trend, and the bound water was partially transformed into free water. The appearance and taste decreased significantly (P < 0.05), and the overall scores of the outer, middle, and inner layers decreased from 66, 65, and 63 to 50, 49, and 50 points, respectively. The hardness increased significantly (P < 0.05), the viscosity decreased significantly (P < 0.05), while no significant change in elasticity was observed. The concentrations of three volatile components in each part of rice ball decreased, while the concentrations of eight other volatile components increased. Rice ball starch exhibited a B-type crystalline structure, and the relative crystallinity of starch in the outer, middle and inner layers increased from 6.21%, 5.14% and 5.24% to 10.62%, 9.99% and 9.23%, respectively. The reticular structure in the cross-section of rice ball collapsed and the pores became heterogeneous in size. At the same storage time, the difference between the outer and inner layers of rice ball was the greatest, and the outer layer was more seriously aged and deteriorated when compared with the inner layer. The results of the study can provide a theoretical basis for the maintenance and improvement of rice ball quality.

Rotation of micro/nano-objects is important for micro/nanorobotics, three-dimensional imaging, and lab-on-a-chip systems. Optical rotation techniques are especially attractive because of their fuel-free and remote operation. However, current techniques require laser beams with designed intensity profile and polarization or objects with sophisticated shapes or optical birefringence. These requirements make it challenging to use simple optical setups for light-driven rotation of many highly symmetric or isotropic objects, including biological cells. Here, we report a universal approach to the out-of-plane rotation of various objects, including spherically symmetric and isotropic particles, using an arbitrary low-power laser beam. Moreover, the laser beam is positioned away from the objects to reduce optical damage from direct illumination. The rotation mechanism based on opto-thermoelectrical coupling is elucidated by rigorous experiments combined with multiscale simulations. With its general applicability and excellent biocompatibility, our universal light-driven rotation platform is instrumental for various scientific research and engineering applications.

Progress in optical manipulation has stimulated remarkable advances in a wide range of fields, including materials science, robotics, medical engineering, and nanotechnology. This Review focuses on an emerging class of optical manipulation techniques, termed heat-mediated optical manipulation. In comparison to conventional optical tweezers that rely on a tightly focused laser beam to trap objects, heat-mediated optical manipulation techniques exploit tailorable optothermo-matter interactions and rich mass transport dynamics to enable versatile control of matter of various compositions, shapes, and sizes. In addition to conventional tweezing, more distinct manipulation modes, including optothermal pulling, nudging, rotating, swimming, oscillating, and walking, have been demonstrated to enhance the functionalities using simple and low-power optics. We start with an introduction to basic physics involved in heat-mediated optical manipulation, highlighting major working mechanisms underpinning a variety of manipulation techniques. Next, we categorize the heat-mediated optical manipulation techniques based on different working mechanisms and discuss working modes, capabilities, and applications for each technique. We conclude this Review with our outlook on current challenges and future opportunities in this rapidly evolving field of heat-mediated optical manipulation.

Optical tweezers offer revolutionary opportunities for both fundamental and applied research in materials science, biology, and medical engineering. However, the requirement of a strongly focused and high-intensity laser beam results in potential photon-induced and thermal damages to target objects, including nanoparticles, cells, and biomolecules. Here, we report a new type of light-based tweezers, termed opto-refrigerative tweezers, which exploit solid-state optical refrigeration and thermophoresis to trap particles and molecules at the laser-generated cold region. While laser refrigeration can avoid photothermal heating, the use of a weakly focused laser beam can further reduce the photodamages to the target object. This novel and noninvasive optical tweezing technique will bring new possibilities in the optical control of nanomaterials and biomolecules for essential applications in nanotechnology, photonics, and life science.

Subwavelength nanostructures with tunable compositions and geometries show favorable optical functionalities for the implementation of nanophotonic systems. Precise and versatile control of structural configurations on solid substrates is essential for their applications in on-chip devices. Here, we report all-solid-phase reconfigurable chiral nanostructures with silicon nanoparticles and nanowires as the building blocks in which the configuration and chiroptical response can be tailored on-demand by dynamic manipulation of the silicon nanoparticle. We reveal that the optical chirality originates from the handedness-dependent coupling between optical resonances of the silicon nanoparticle and the silicon nanowire via numerical simulations and coupled-mode theory analysis. Furthermore, the coexisting electric and magnetic resonances support strong enhancement of optical near-field chirality, which enables label-free enantiodiscrimination of biomolecules in single nanostructures. Our results not only provide insight into the design of functional high-index materials but also bring new strategies to develop adaptive devices for photonic and electronic applications.

Opto-thermoelectric tweezers (OTET), which exploit the thermophoretic matter migration under a light-directed temperature field, present a new platform for manipulating colloidal particles with a wide range of materials, sizes, and shapes. Taking advantage of the entropically favorable photon-phonon conversion in light-absorbing materials and spatial separation of dissolved ions in electrolytes, OTET can manipulate the particles in a low-power and high-resolution fashion. In this mini-review, we summarize the concept, working principles, and applications of OTET. Recent developments of OTET in three-dimensional manipulation and parallel trapping of particles are discussed thoroughly. We further present their initial applications in particle filtration and biological studies. With their future development, OTET are expected to find a wide range of applications in life sciences, nanomedicine, colloidal sciences, photonics, and materials sciences.

Background and Objectives: At present, there are no sufficient data in the literature about the effect of extruded wheat bran on the volatility and physical–chemical properties of bread during frozen storage. Therefore, the current study aimed to investigate the effect of extruded wheat bran on the volatile components and physical–chemical properties of bread during frozen storage. Findings: Frozen storage could effectively extend the shelf‐life of bread. After 20 days of storage, the specific volume and cohesion of the control breads decreased significantly (2% and 21.55%, respectively). Moreover, the hardness and amylopectin retrogradation degree increased significantly (81.56%). After 30 days of storage, the amylopectin retrogradation degree of extruded wheat bran breads significantly increased (161%). After 40 days of storage, the cohesion of extruded wheat bran breads decreased significantly (7.67%). Extruded bran was conducive for improving bread stability during frozen storage. The transverse relaxation times (T2) of extruded wheat bran bread were shorter than those of the control bread. Bran inhibited water molecule migration and reduced the rate of bread quality deterioration. Further, 27 volatile components were detected in the control bread and 32 volatile components were detected in extruded wheat bran breads. The volatile components of all breads did not change significantly within the first 30 days of storage. Thereafter, the concentration of some volatile compounds decreased. Conclusion: The addition of extruded wheat bran significantly affected the volatility and physical–chemical properties of bread during frozen storage. The volatility and physical–chemical properties of extruded wheat bran bread changed gradually during frozen storage. The presence of bran inhibited water molecule migration and the formation and recrystallization of large ice crystals, and reduced the rate of bread quality deterioration during frozen storage. Significance and Novelty: This study aimed to provide a reference for research on the storage and long‐term preservation of extruded wheat bran bread after production. [ABSTRACT FROM AUTHOR]

IntroductionLupus nephritis (LN) is a major risk factor of morbidity and mortality. Glomerular injury is associated with different pathogeneses and clinical presentations in LN patients. However, the molecular mechanisms involved are not well understood. This study aimed to explore the molecular characteristics and mechanisms of this disease using bioinformatics analysis.MethodsTo characterize glomeruli in LN, microarray datasets GSE113342 and GSE32591 were downloaded from the Gene Expression Omnibus database and analyzed to determine the differentially expressed genes (DEGs) between LN glomeruli and normal glomeruli. Functional enrichment analyses and protein–protein interaction network analyses were then performed. Module analysis was performed using the Search Tool for the Retrieval of Interacting Genes/Proteins and Cytoscape software. Immunofluorescence staining was performed to identify the glomerular expression of S100A8 in various International Society of Nephrology/Renal Pathology Society (ISN/RPS) class LN patients. The image of each glomerulus was acquired using a digital imaging system, and the green fluorescence intensity was quantified using Image-Pro Plus software.ResultsA total of 13 DEGs, consisting of 12 downregulated genes and one upregulated gene (S100A8), were identified in the microarray datasets. The functions and pathways associated with the DEGs mainly include inflammatory response, innate immune response, neutrophil chemotaxis, leukocyte migration, cell adhesion, cell–cell signaling, and infection. We also found that monocytes and activated natural killer cells were upregulated in both GSE113342 and GSE32591. Glomerular S100A8 staining was significantly enhanced compared to that in the controls, especially in class IV.ConclusionsThe DEGs identified in the present study help us understand the underlying molecular mechanisms of LN. Our results show that glomerular S100A8 expression varies in different pathological types; however, further research is required to confirm the role of S100A8 in LN.

Mild cognitive impairment (MCI) is a critical prodromal stage of Alzheimer's disease (AD), and the mechanism underlying the conversion is not fully explored. Construction and inter‐cohort validation of imaging biomarkers for predicting MCI conversion is of great challenge at present, due to lack of longitudinal cohorts and poor reproducibility of various study‐specific imaging indices. We proposed a novel framework for inter‐cohort MCI conversion prediction, involving comparison of structural, static, and dynamic functional brain features from structural magnetic resonance imaging (sMRI) and resting‐state functional MRI (fMRI) between MCI converters (MCI_C) and non‐converters (MCI_NC), and support vector machine for construction of prediction models. A total of 218 MCI patients with 3‐year follow‐up outcome were selected from two independent cohorts: Shanghai Memory Study cohort for internal cross‐validation, and Alzheimer's Disease Neuroimaging Initiative (ADNI) cohort for external validation. In comparison with MCI_NC, MCI_C were mainly characterized by atrophy, regional hyperactivity and inter‐network hypo‐connectivity, and dynamic alterations characterized by regional and connectional instability, involving medial temporal lobe (MTL), posterior parietal cortex (PPC), and occipital cortex. All imaging‐based prediction models achieved an area under the curve (AUC) > 0.7 in both cohorts, with the multi‐modality MRI models as the best with excellent performances of AUC > 0.85. Notably, the combination of static and dynamic fMRI resulted in overall better performance as relative to static or dynamic fMRI solely, supporting the contribution of dynamic features. This inter‐cohort validation study provides a new insight into the mechanisms of MCI conversion involving brain dynamics, and paves a way for clinical use of structural and functional MRI biomarkers in future. [ABSTRACT FROM AUTHOR]