Search

Understanding the exact localization of nanoparticles within cell is of particular importance for rational design of high-effective nanomedicines. In the present study, direct stochastic optical reconstruction microscopy (dSTORM) is employed to elucidate the precise localization of nanoparticles within cells owing to its superiority of nanometric resolution, multicolour ability and minimal invasiveness. The localization of the Cy5 labelled mesoporous silica nanoparticles (MSNs-Cy5) in MCF-7 cells are monitored by dSTORM and conventional fluorescence microscopy, respectively. The dSTORM images demonstrate much higher spatial resolution for locating MSNs-Cy5 within cells compared to that of the conventional fluorescence images. Moreover, the distribution of MSNs-Cy5 within three cell lines over time are obtained. For the MCF-7 and HeLa cells, MSNs-Cy5 nanoparticles distribute nearly all around the cytoplasm after 5 h incubation. In contrast, MSNs-Cy5 nanoparticles within NIH 3T3 cells are quite different that they are found to be either attached to or embedded into cell membranes, without penetrating into the cytoplasm. Overall, we provide a practical method to reveal the in situ precise imaging of nanoparticles in cells with nanometric resolution precision. This method may open up new opportunities for organelle-specific targeting drug delivery to achieve maximum therapeutic benefit.

Background Phospholipases As (PLAs) are acyl hydrolase that can catalyze the release of free fatty acids in phospholipids and play multiple functions in plant growth and development. PLAs can be divided into three families, PLA1, PLA2 (sPLA) and patatin-related PLA (pPLA). Previous studies have elucidated the versatile roles of pPLAs in growth and development of many plants.Methods Genome-wide analysis of the pPLA family and screening of genes for expression verification and gene silencing verification. After gene silencing, analysis of pollen expression pattern, pollen vitality test and POD, SOD, CAT, MDA and H2O2 detection.Result In this study, a total of 294 pPLAs were identified from 13 species, including 46 GhpPLAs divided into three subfamilies (I-III-γ). Expression pattern analysis revealed that most of GhpPLAs were preferentially expressed in the reproductive organs (petal, pistil, anther and ovule), especially two genes (GhpPLA23 and GhpPLA44) were deduced that may affect the reproductive development of G. hirsutum. VIGS experiment of GhpPLA23 and GhpPLA44 showed that the pollen activity decreased with their lower expression levels in the silenced plants. The contents of POD, CAT, SOD and other physiological indicators were significantly increased, while ROS and ROS scavengers were significantly changed after genes silencing, indicating that these two genes had important effects on cotton reproductive development. These findings suggest that pPLAs play a crucial role in reproductive development of G. hirsutum and show the potential to be utilized as candidate genes for haploid inducing.Conclusions In this study, pPLA genes play an important role in the reproductive organs of cotton, affecting the development of flower organs and sperm cells, so this family may play an important role in the reproductive development progress of cotton, and even in inducing cotton to produce haploid.

Inspired by the self-assembly phenomena in nature, the instructed self-assembly of exogenous small molecules in a biological environment has become a prevalent process to control cell fate. Despite mounting examples of versatile bioactivities, the underlying mechanism remains less understood, which is in large hindered by the difficulties in the identification of those dynamic assemblies in situ. Here, with direct stochastic optical reconstruction microscopy, we are able to elucidate the dynamic morphology transformation of the enzyme-instructed supramolecular assemblies in situ inside cancer cells with a resolution below 50 nm. It indicates that the assembling molecules endure drastically different pathways between cell lines with different phosphatase activities and distribution. In HeLa cells, the direct formation of intracellular supramolecular nanofibers showed slight cytotoxicity, which was due to the possible cellular secretory pathway to excrete those exogenous molecules assemblies. In contrast, in Saos-2 cells with active phosphatase on the cell surface, assemblies with granular morphology first formed on the cell membranes, followed by a transformation into nanofibers and accumulation in cells, which induced Saos-2 cell death eventually. Overall, we provided a convenient method to reveal the in situ dynamic nanomorphology transformation of the supramolecular assemblies in a biological environment, in order to decipher their diverse biological activities.

The energy router (ER) is key to realizing the coordinated management and efficient utilization of multiple forms of energy in Energy Internet. This paper proposes a novel design and configuration method for the physical layer of ER by using complex network theory. Firstly, an abstract model of the physical layer of ER is introduced according to its function, and important modules in the model are illustrated in details. Secondly, based on the electrical characteristics of ports, the community structure of the power networks inside ER is analyzed by the improved Girvan-Newman (GN) algorithm to design the independent bus systems (IBSs) and generate the network topology of the physical layer. Then, the optimization model of equipment configuration of the power supply and distribution systems of ER is developed considering the economy, utilization efficiency, and power supply reliability. Finally, two case studies demonstrate that the proposed strategy can effectively accomplish the module-level structure design and device configuration for the physical layer of ER.

Molecular assemblies of cationic dipeptide-gold nanoparticle (CDP-AuNP) hybrid microspheres were used to modify cholesterol oxidase electrodes for high-sensitivity cholesterol detection. The cationic dipeptide used here serves as a functional molecule for adsorbing chloroauric acid based on electrostatic interactions and assembly into spherical structures, providing a platform for loading gold nanoparticles (AuNPs), increasing the immobilization load of the enzyme and maintaining the activity of the enzyme as a result of excellent biocompatibility. Moreover, the CDP-AuNP modified cholesterol oxidase electrode has a higher electrocatalytic activity to cholesterol with obvious enhancement in the current response, exhibiting a current response 13 times higher than that of the controlled electrode. The outstanding biocompatibility and increased enzyme load by hybrid microspheres and the good charge-transfer ability of AuNPs in the peptide-based electrode indicate a very attractive perspective in the field of biodevices.

Peptide-based supramolecular self-assembly from peptide monomers into well-organized nanostructures, has attracted extensive attentions towards biomedical and biotechnological applications in recent decades. This spontaneous and reversible assembly process involving non-covalent bonding interactions can be artificially regulated. In this review, we have elaborated different strategies to modulate the peptide self-assembly through tuning the physicochemical and environmental conditions, including pH, light, temperature, solvent, and enzyme. Detailed introduction of biological applications and future potential of the peptide-based nano-assemblies will also be given.

Hypothesis Crystalline self-assemblies of diphenylalanine (FF) are since long back considered to be related to Alzheimer's disease. An improved understanding of the mechanism behind the formation of such structures can lead to strategies for investigating the dynamic processes of assembly and disassembly of FF. Experiment The assembly, disassembly and reassembly of FF crystals are influenced by the solvent composition and can be triggered by evaporation of solvent. In this work these processes are directly monitored, and the structures obtained are analyzed. Findings The role of the solvent for assembly, disassembly and reassembly of diphenylalanine crystals has been demonstrated. The initial crystal structure formed via self-assembly of FF monomers can be transformed into needle-like crystals and further to hollow hexagonal microtubes through evaporation of the solvent. It is shown that all the assembly-disassembly processes are spontaneous and driven by thermodynamics. It is also found that some of the crystalline structures exhibit optical waveguiding properties.

Achieving synthetic architectures with simple structures and robust biomimetic catalytic activities remains a great challenge. Herein, we explore a facile supramolecular assembly approach to construct a dipeptide-based hierarchical nanoarchitecture with enhanced enzyme-like catalytic activity. In this nanoarchitecture, nanospheres are put in a chain-like arrangement through coordination-driven directional self-assembly. The reversible transformation of anisotropic nanochains to isotropic nanospheres switches biomimetic activity. Notably, the assembled nanoarchitecture exhibits a high enzyme-like activity and remarkable long-term stability to promote hydroquinone oxidation, superior to the natural counterpart. This work will pave the way to develop reversible and reusable supramolecular biocatalysts with ordered hierarchical structures for accelerating chemical transformations.

Inspired by the self-assembly phenomena in nature, the instructed self-assembly of exogenous small molecules in a biological environment has become a prevalent process to control cell fate. Despite mounting examples of versatile bioactivities, the underlying mechanism remains less understood, which is in large hindered by the difficulties in the identification of those dynamic assemblies

A natural-artificial hybrid system was constructed to enhance photophosphorylation. The system comprises chloroplasts modified with optically matched quantum dots (chloroplast-QD) with a large Stokes shift. The QDs possess a unique optical property and transform ultraviolet light into available and highly effective red light for use by chloroplasts. This favorable feature enables photosystem II contained within the hybrid system to split more water and produce more protons than chloroplasts would otherwise do on their own. Consequently, a larger proton gradient is generated and photophosphorylation is improved. At optimal efficiency activity increased by up to 2.3 times compared to pristine chloroplasts. Importantly, the degree of overlap between emission of the QDs and absorption of chloroplasts exerts a strong influence on the photophosphorylation efficiency. The chloroplast-QD hybrid presents an efficient solar energy conversion route, which involves a rational combination of a natural system and an artificial light-harvesting nanomaterial.

We report that templated by supramolecular assembly through electrostatic interaction and π-π stacking, one-dimensional gold hierarchical nanostructures are fabricated after chemical reduction in situ. It is found that through Ostwald ripening, such assembled complexes evolve from metastable nanospheres to stable microfibers. After reduction of these microfibers, one-dimensional gold hierarchical nanostructures composed of nanoparticles are obtained. Interestingly, the special hierarchical nanostructures exhibit different surface plasmon resonance property from conventional gold nanoparticles, having potential applications for photoelectronic devices. This work opens a new route to construct noble metal or their alloy nanostructures with hierarchy.

Energy Internet, which is regarded as the new generation energy utilization system, is an ideal solution to achieve sustainable development. In this paper, we propose a park-type Energy Local Area Network (ELAN) planning method for the planning and operation control of the ELAN. Firstly, we classify the park from its industrial structure and analyse the positioning of the park in terms of energy, environment, and load factors. Then, the physical planning architecture of the park-type ELAN is built. Subsequently, a planning method of park-type ELAN is proposed, which can incorporate the optimization problem of multi-energy cooperative scheduling into the planning model. Finally, the effectiveness of the proposed method is verified by performing calculations with a solid waste treatment park system.

In order to solve the problems of low space utilization rate and insufficient power supply reliability of substations, a multi-station fusion technology with substations as the main body and multiple power stations (5G communication base station, electric vehicle charging station, data center and energy storage station) was proposed. In this paper, the layered structure of the new fusion power station with “multi-station fusion” is proposed to clarify the collaborative working mode of various parts in the new fusion power station through the layered structure, so as to prevent equipment failures caused by interlocking control information. At the same time, the topological structure of the energy transfer layer of the new fusion power station is designed, and the MMC module is used in the energy transfer layer for energy transmission. Then the verification procedure, analysis of the circuit feasibility of the output waveform and control of the signal waveform are realized on the hardware circuit.

Enhancing solar energy conversion efficiency is very important for developing renewable energy, protecting the environment, and producing agricultural products. Efficient enhancement of photophosphorylation is demonstrated by coupling artificial photoacid generators (PAGs) with chloroplasts. The encapsulation of small molecular long-lived PAGs in the thylakoid lumen is improved greatly by ultrasonication. Under visible-light irradiation, a fast intramolecular photoreaction of the PAG occurs and produces many protons, remarkably enhancing the proton gradient in situ. Consequently, compared to pure chloroplasts, the assembled natural-artificial hybrid demonstrates approximately 3.9 times greater adenosine triphosphate (ATP) production. This work will provide new opportunities for constructing enhanced solar energy conversion systems.

Sunpreme combines Hybrid Cell Technology (HCT) with proven processes from the microelectronics industry to develop a simplified toolset and process for copper metallization on bifacial Si heterojunction cells. The result yields over 24% efficiency with a production ready process using standard production n-type Cz c-Si wafers (large area cell 244.3cm2). The cell starts from grid patterning through Cu electrochemical plating to achieve 20um width and 30um height fingers. All Cu metallization process and equipment use optimized PCB industry standard concepts to handle thin, fragile silicon wafers in high volume manufacturing, reducing all-in cost below $0.32/Wp. This low-cost, high-throughput manufacturing process captures the advantages of Cu (narrower fingers line width, lower resistivity and lower material cost) without the added costs of state of the art Cu-on-Silicon PV manufacturing methods and will yield 3.7¢/kWh LCOE. Sunpreme Cu metallization development project is funded by two US government grants.

Tunable supramolecular assembly has found various applications in biomedicine, molecular catalysis, optoelectronics, and nanofabrication. Unlike traditional covalent conjugation, non-covalent introduction of a photoswitchable moiety enables reversible photomodulation of non-photosensitive dipeptide supramolecular assembly. Under light illumination, a long-lived photoacid generator releases a proton and mediates the dissociation of dipeptide-based organogel, thereby resulting in sol formation. Under darkness, the photoswitchable moiety entraps a proton, resulting in gel regeneration. Furthermore, accompanying the isothermal recycled gel-sol transition in a spatially controlled manner, renewable patterns are spontaneously fabricated. This new concept of light-controlled phase transition of amino acid-based supramolecular assemblies will open up the possibility of wide applications.

This paper presents the numerical simulation of heat transfer and solidification process in an industrial silicon directional solidification system. The energy efficiency in the production system is analyzed. The effects of the heating power and the position of the side insulation layer on the solidification interface position/shape are investigated. The numerical results indicate that the directional solidification of the silicon can be controlled by adjusting the heating power and moving the side insulation layer. The knowledge gained from the thermal analysis can be used to improve the energy efficiency in the current silicon production system. An easy method to detect the solidification interface shape was proposed and has been conceptually proven.

In real life, the phenomenon of vehicle queue always happens in loading and unloading freight yard, loading and unloading equipment idle always happens too, the equipment can't be used sufficiently, this is a waste of resources and will cost more. This kind of circumstance appears not only relates to the number of loading and unloading equipment, but also relates to the way of vehicle queue. This paper will apply the queue model, with the help of Matlab to determine the way of vehicle queue and the number of loading and unloading equipment, in order to improve the service efficiency, reduce the operational costs

In a continuous Czochralski (CCZ) growth system with a shallow and replenished melt proposed earlier, large-diameter crystals may be grown at a high pull rate and reduced melt convection. The proposed system consists of two heaters. In this paper, the relationship between the solidification interface and the power levels is established. An interface control algorithm is developed to achieve the desired interface shape by adjusting the power level of the bottom heater. The control algorithm is incorporated into an existing process model, and the efficiency of the control algorithm is tested.

The edge-defined film-fed (EFG) growth involves multi-physics and multiple time/length scales. A numerical model based on multi-block method and multi-grid technique is developed for induction heating and thermal transport in an EFG system. The magnetic potential is solved on a single block structured grid using V-cycle multi-grid method and a non-conformal multi-block system is employed to resolve the multi-length-scale phenomena in thermal transport. A local model, which can reveal the EFG growth dynamics on the die top, is also developed integrated with the global model. Efficiency and accuracy of proposed integrated method is presented. The numerical model is applied to investigate the growth of large octagon silicon tubes up to 50 cm diameter.

Solar cells based on n-type upgraded metallurgical grade multicrystalline silicon (mc-Si) substrates may be a promising path for reducing the cost per watt of photovoltaics. The detrimental effect of metal point defects in both n- and p-type silicon is known, but the recombination activity of metal-silicide precipitates, especially in n-type mc-Si, is still not well established, impeding modeling and process optimization efforts. In this contribution, we provide a rationale for why metal-rich precipitates may limit minority-carrier lifetime in n-type mc-Si, in contrast to as-grown p-type mc-Si, which is dominated by metal point defects. Using μ-XRF, we identify metal-rich precipitates along a recombination active grain boundary in the low-lifetime “red zone” region of n-type wafers from a corner brick. To reduce the concentration of precipitated metals, we phosphorus-diffuse the wafers. Grain boundaries remain recombination active, which may be attributed to incomplete gettering of point defects and dissolution of recombination-active metal-rich precipitates.

We have developed a manufacturing- and field-worthy technology based on low cost p-type MG and n-type UMG active absorbers. By optimizing the casting process, we are able to achieve good carrier mobility. The cell is then enabled with a-Si:H for the surface passivation, emitter, back surface field and back reflector. The efficiencies are close to mainstream diffused junction cells, but with a much lower thermal coefficient of efficiency and 70~75% lower energy budget. Moreover the emitter current distribution is largely independent of underlying defects in the MG-Si. Hence the cells can be scaled to larger wafer sizes with cost benefits previously seen for semiconductors and flat-panel LCD's.

Solar cells based on n-type multicrystalline silicon (mc-Si) wafers are a promising path to reduce the cost per kWh of photovoltaics; however, the full potential of the material and how to optimally process it are still unknown. Process optimization requires knowledge of the response of the metal-silicide precipitate distribution to processing, which has yet to be directly measured and quantified. To supply this missing piece, we use synchrotron-based micro-X-ray fluorescence (μ-XRF) to quantitatively map >250 metal-rich particles in n-type mc-Si wafers before and after phosphorus diffusion gettering (PDG). We find that 820 °C PDG is sufficient to remove precipitates of fast-diffusing impurities and that 920 °C PDG can eliminate precipitated Fe to below the detection limit of μ-XRF. Thus, the evolution of precipitated metal impurities during PDG is observed to be similar for n- and p-type mc-Si, an observation consistent with calculations of the driving forces for precipitate dissolution and segregation gettering. Measurements show that minority-carrier lifetime increases with increasing precipitate dissolution from 820 °C to 880 °C PDG, and that the lifetime after PDG at 920 °C is between the lifetimes achieved after 820 °C and 880 °C PDG.

This study investigated the non-metallic inclusions in Solar Grade Silicon (SoG-Si), especially the distribution of inclusions in the top 15mm layer of multicrystalline silicon ingot. The SoG-Si ingot produced from directional solidification process usually pushes the impurities to the top and finally cut off and discarded, which leads to material loss. The hard inclusions lead to wire breakages during the cutting of the ingot into wafers. The main kinds of inclusions found in top-cut silicon scraps from two manufacturers have been investigated using acid extraction, automated feature analysis techniques and SEM-EDS and optical Microscope: they are needle-like Si 3 N 4 and lumpy SiC inclusions. Surface observations of the scraps before polishing revealed that, Si3N4 inclusions are usually bigger and in some cases can be about a few millimeters. SiC inclusions are usually smaller, ∼200µm but can be ∼500µm in some cases. For the directional solidified silicon ingot, it was determined that an approximate distance of ∼10mm is a good enough cutoff thickness.

Progressively expanding of photovoltaic industry has caused worldwide silicon feedstock shortage. The fast growth of high quality thin tubes is critical to achieve high solar cell efficiency while reducing the consumption of raw materials. A previously developed comprehensive two-dimensional global model, has been used to predict electromagnetic induction heating and heat and mass transfer in the entire growth system. To achieve more accurate simulation results, a two dimensional local model is developed to simulate the temperature distribution along the silicon tube and temperature gradient at the solid-liquid interface, which are critical for stable growth, and residual stress. The radiation, convection and conduction heat transfer between silicon tube and environment and treatments of solid-liquid interface movement and solidification latent heat generation at the growth interface are discussed in this paper. Simulation results of the electromagnetic and temperature fields for a large diameter EFG is presented. A one-dimensional dynamic model is used to study the oscillation of silicon tube thickness under different conditions. Parametric studies have been performed to study the effects of pull rate and tube thickness on tube temperature distribution and tube quality. The effects of different carrying gas flow rates will also be investigated. The relationship between the temperature profile along the silicon tube and the silicon tube thickness, pull rate, and gas flow rate is established.Copyright © 2005 by ASME

A comprehensive two-dimensional numerical model, which accounts for heat/mass transfer, solidification, and electromagnetic field, has been developed to simulate the silicon tube growth by the edge-defined film-fed (EFG) method. A multi-block grid system has been employed to yield a high accuracy in the vicinity of die tip with relatively low CPU time. Selected results of magnetic and temperature fields have been presented for the silicon tube growth system of 30cm in diameter and 0.3mm in thickness. Based on elastic assumption, the mechanism of buckling behavior of the as-grown tube has been analyzed.

A comprehensive two-dimensional numerical model, which accounts for heat/mass transfer, solidification, and electromagnetic field, has been developed to simulate the silicon tube growth by the Edge-defined film-fed (EFG) method. A multi-block grid system has been employed to yield a high accuracy in the vicinity of die tip with relatively low CPU time, and the solution procedure is satisfied the flux conservation at the block interface. Selected results of magnetic and temperature fields have been presented for the silicon tube growth system of 30cm in diameter and 0.3mm in thickness. Two local models have also been developed to study the effect of the size of window opening and tube thickness on the maximum growth rate using the inner and outer heater temperature profiles as boundary conditions.Copyright © 2003 by ASME

A gel-to-crystal phase transition of a dipeptide supramolecular assembly mediates active water transportation in oils. The addition of water into ultrafast-assembling dipeptide organogels can induce a lamellar-to-hexagonal structural transformation of dipeptide molecular arrangement. Consequently, a phase transition from gel to crystal occurs and in turn water is transported in the dipeptide crystal via well-defined channels. On a macroscopic scale, water transport in the bulk system exhibits an anisotropic characteristic, which can be tuned by the presence of ions in the Hofmeister series. These favorable features enable the automatic separation of dispersed nanoparticles from dissolved electrolytes in aqueous solution. These findings demonstrate the potential of this assembled system for active filtration without external pressure.