Dispersion Of Aggregates Research Articles

The Spatial Pedigree in Traditional Villages under the Perspective of Urban Regeneration—Taking 728 Villages in Jiangnan Region, China as Cases

In current urban regeneration, the conservation and reuse of traditional village space are significant measures to activate urban-rural development. Traditional villages in the Jiangnan region of eastern China represent the typical vernacular culture of urban-rural settlements, which affects the dynamic development of urban regeneration. Aiming at the disadvantages of the decentralization of research objects and the simplification of spatial characteristics in the research of traditional villages in the Jiangnan region, this paper will construct the spatial pedigrees of villages. This study takes 728 traditional villages in the Jiangnan region as cases. First, through on-site research, the spatial pattern of villages in isolated areas was mapped and drawn. Then, on the basis of on-site review, this study labeled the village space, summarized village space information, and used ArcGIS and BIM to create a 3D model of the village. In ArcGIS platform through SOA to establish criterion framework for recognizing the types of village pedigree. Finally, the classification of villages was spatially visualized, and a pedigree was constructed according to the type context. The research result indicates: (1) The aggregation mode of traditional villages in the south of the Jiangnan region presents the characteristics of local aggregation and partial dispersion, which are directly affected by factors such as elevation, water system, and road system. (2) Analysis of the spatial pedigrees of traditional villages through spatial types and spatial growth patterns revealed four pedigree types, including spatial environment pedigree, the spatial organization pedigree, spatial morphological pedigree, and architectural form pedigree. (3) The pedigree shows and distinguishes independent developmental context and evolved form, presenting an extended pattern of prototypes and sub-types.

Tetraalkylammonium and phosphonium salt for asphaltene dispersion; experimental studies on interaction mechanisms

Asphaltenes deposition is one of the most severe problems in the petroleum industry, imposing high costs on oil producer companies. The use of chemical dispersants reduces the risk of asphaltene deposition. For this purpose, a variety of chemicals with different structures and functional groups were designed and synthesized. Organic quaternary salts, such as ionic liquids, have been widely used to control asphaltene deposition over the last two decades, but the mechanism of their interaction with asphaltene has not been studied in detail. In this study, the interaction of ten commercial quaternary ammonium and phosphonium salts with asphaltene molecules was investigated using ultraviolet-visible (UV-Vis) spectroscopy. It was observed that the size, shape, and hydrophobicity of their cations or anions play an essential role in the dispersion of asphaltene aggregations. The results showed that the interaction of these quaternary salts is strongly influenced by the hydrophobic nature of the salt, and salts with more hydrophobic cations and anions, such as tetrabutylammonium iodide, tetrabutylammonium hexafluorophosphate, and cetyltrimethylammonium bromide, can better disperse asphaltene aggregations. The results also revealed that the role of anions such as iodide, and hexafluorophosphate in the dispersion of asphaltene aggregates is more important than cations. In addition, the results showed that except for tetramethylammonium bromide, the efficiency of the salts was increased with increasing concentration.

Spatiotemporal evolution of online attention to vaccines since 2011: An empirical study in China

Since the outbreak of Coronavirus Disease 2019 (COVID-19), the Chinese government has taken a number of measures to effectively control the pandemic. By the end of 2021, China achieved a full vaccination rate higher than 85%. The Chinese Plan provides an important model for the global fight against COVID-19. Internet search reflects the public's attention toward and potential demand for a particular thing. Research on the spatiotemporal characteristics of online attention to vaccines can determine the spatiotemporal distribution of vaccine demand in China and provides a basis for global public health policy making. This study analyzes the spatiotemporal characteristics of online attention to vaccines and their influencing factors in 31 provinces/municipalities in mainland China with Baidu Index as the data source by using geographic concentration index, coefficient of variation, GeoDetector, and other methods. The following findings are presented. First, online attention to vaccines showed an overall upward trend in China since 2011, especially after 2016. Significant seasonal differences and an unbalanced monthly distribution were observed. Second, there was an obvious geographical imbalance in online attention to vaccines among the provinces/municipalities, generally exhibiting a spatial pattern of “high in the east and low in the west.” Low aggregation and obvious spatial dispersion among the provinces/municipalities were also observed. The geographic distribution of hot and cold spots of online attention to vaccines has clear boundaries. The hot spots are mainly distributed in the central-eastern provinces and the cold spots are in the western provinces. Third, the spatiotemporal differences in online attention to vaccines are the combined result of socioeconomic level, socio-demographic characteristics, and disease control level.

Organic amendments and gypsum reduce dispersion and increase aggregation of two sodic Vertisols

Sodic soils are widespread in semi-arid and arid regions of the world, with agricultural production on these soils constrained due to structural instability resulting from high concentration of exchangeable sodium (Na). The structural instability results in clay dispersion, reduced infiltration, crust formation and poor seed germination. One way to decrease undesirable effects of Na on soil structure is to apply gypsum (G) and organic amendments. We evaluated the effect of G and four organic amendments [polyacrylamide (PAM), feedlot manure (FLM), chicken manure (CM), and lucerne pellets (LP)] on two sodic soils. These amendments differed in their chemical nature as assessed by 13C cross-polarisation magic angle spinning nuclear magnetic resonance (13C CPMAS NMR) spectroscopy after amended soils were incubated for 60 d at field water capacity. Gypsum reduced dispersion but had no effect on macroaggregates or aggregate mean weight diameter (MWD). Using principal component analysis, we found that aryl C and O-aryl C functional groups were positively correlated with microaggregates and the silt + clay fraction, and O-alkyl C and di-O alkyl C were positively correlated with soil dispersion after 1 d of soil incubation. The CM reduced dispersion more than FLM, LP, or PAM, although LP increased the proportion of large macroaggregates and MWD. We also found that large macroaggregates and MWD were positively correlated with microbial respiration and dissolved organic carbon. Except for the G + LP amendment, G had no synergistic effect with other organic amendments on macroaggregates and MWD of the two sodic soils. This study demonstrates that the functional groups of organic amendments and microbial activity play important roles in aggregation and dispersion of sodic soils. This study also demonstrates that a combination of gypsum and organic amendments will be a better option to ameliorate sodic soils by decreasing dispersion and increasing aggregate formation.

Improving the Mechanical Resistance of Hydroxyapatite/Chitosan Composite Materials Made of Nanofibers with Crystalline Preferential Orientation.

The stability and mechanical properties of hydroxyapatite (HAp)/Chitosan composite materials depend on the dispersion of HAp aggregates in the chitosan matrix and on the chemical interaction between them. Therefore, hexagonal cross-sectioned HAp nanofibers were produced using a microwave-assisted hydrothermal method. Glutamic acid was used to control the HAp crystal growth; thereby, nanofibers were obtained with a preferential crystalline orientation, and they were grown along the “c” axis of HAp crystal structures. This morphology exposed the (300) and (100) crystal planes on the surface, and several phosphate groups and calcium ions were also exposed; they were able to form numerous chemical interactions with the amine, hydroxyl, and carbonyl groups of chitosan. Consequently, the final mechanical resistance of the composite materials was synergistically increased. Nanofibers were mixed with commercial chitosan using a sonotrode to improve their dispersion within the biopolymer matrix and prevent migration. The HAp nanofiber/Chitosan composite materials showed higher mechanical resistance than that observed in similar materials with the same chemical composition that were made of commercial HAp powders, which were used as reference materials. The mechanical resistance under tension of the composite materials made of nanofibers was similar to that reported for cortical bone.

Dimethyl ether conversion to hydrocarbons on the closely interconnected FER@ZSM-5 nanostructures

A superior catalyst activity and stability for dimethyl ether (DME) conversion to gasoline-range hydrocarbons (DTG) on a novel hierarchically-structured hybridized FER@ZSM-5 were verified in terms of the strong interactions of ZSM-5 on the plate-like FER nanostructures, which were prepared by alcohol additive with two organic structure-directing agent (OSDA). The highly active nanostructured FER@ZSM-5 with a propanol additive showed the closely interconnected and highly dispersed ZSM-5 aggregates on the larger plate-like FER surfaces, which were mainly responsible for the suppressed heavy coke depositions with the help of the closely interconnected ZSM-5 and FER interfaces with abundant acidic sites on 8-membered ring (8-MR) channels. The well-dispersed ZSM-5 nanoparticles on Brønsted acid sites of FER surfaces showed coke-resistant natures for DTG reaction due to the synergy effects of the strong acidic sites of the smaller ZSM-5 particles and larger Brønsted acid sites on the plate-like FER structures. • Superior activity and stability for DTG on the hybrid FER@ZSM-5 composite were verified. • FER@ZSM-5(Propanol) with closely interconnected nanostructures showed higher stability. • Less coke deposition was observed due to closely interconnected ZSM-5 and FER interfaces.

Simple Approach to Assess the Maximum Hot Spot SERS Enhancement Factors in Colloidal Dispersions of Gold Nanoparticle Aggregates

Simple Approach to Assess the Maximum Hot Spot SERS Enhancement Factors in Colloidal Dispersions of Gold Nanoparticle Aggregates

Effect of surfactants on vitrified bond diamond composites prepared by sol-gel and dispersibility of diamond

Vitrified ultrafine diamond grinding wheels are ideal for machining next-generation semiconductor power device material, such as SiC etc. However, a crucial problem limiting the application of ultrafine diamond originates from the dispersion of aggregates in vitrified bond. In this study, in can be confirmed that the preparation of uniformly dispersed diamond/vitrified bond composites using sol-gel technique is feasible. Surfactants with various types and additions interactively promote the dispersion of diamond, which make both the bending strength and diamond dispersion of the composites are suitable for precision grinding. The results are valuable for the preparation of vitrified grinding wheels with ultrafine diamond for precision machining of semiconductor.

Application of a novel amphiphilic polymer for enhanced offshore heavy oil recovery: Mechanistic study and core displacement test

A molecular modified polyacrylamide with Gemini surfactant monomers, named as HA1, was evaluated in this paper as an alternative to enhance the offshore heavy oil recovery. The physical properties of HA1 solution including apparent viscosity, rheological properties, static adsorption, interfacial activities (IFT, interfacial visco-elasticity and contact angle), emulsification ability, as well as oil recovery capacity were comprehensively investigated. Our results indicate that due to the hydrophobic and Gemini surfactant monomers on the acrylamide backbone, this novel amphiphilic polymer possesses more advanced functions than conventional polymers. HA1 demonstrates pronounced aqueous-phase viscosifying ability by forming 3D network in solution when the concentration is above CAC. In addition, the IFT, interfacial visco-elasticity and contact angle response illustrate that HA1 interacts strongly with the oil-phase which gives rise to its significant interfacial activity. Thereby, HA1 is able to reduce the heavy oil viscosity by emulsifying oil into water phase even at relatively low water content (20%) and also avoids dehydration difficulty by reducing the oil-brine interfacial rigidity. Furthermore, the asphaltene morphology change due to HA1 observed by SEM and AFM proves that HA1 can disperse the asphaltene aggregates in the crude oil, leading to a direct reduction of the heavy oil viscosity. At last, the coreflooding in an artificially synthesized triple-layered porous media shows that HA1 gives rise to an additional oil recovery of 27.04%, at the optimum concentration of 1600 ppm, by improving sweep efficiency, microscopic efficiency and dispersion of the asphaltene aggregates. Therefore, the potential of HA1 to enhance heavy oil recovery is comparable to traditional multi-component polymer-surfactant flooding. Since HA1 is single-component, it can also mitigate incompatibility issues like chromatography separation and surfactant-polymer interactions. Overall, this new self-assembly system shows potential for applications in heavy oil recovery.

Multi-scale description of hydro-mechanical coupling in swelling clays. Part I: Nonlinear poroelasticity

This paper presents a micromechanical description of the swelling behavior of partially saturated clays following a two-stage homogenization procedure on a three-dimensional Representative Elementary Volume (REV) of clay. At the nano-scale, the REV of clay particles includes idealized parallel clay platelets and oblate spheroidal pores in between them that are saturated with an electrolyte solution. Swelling forces at all spacing ranges, including the crystalline and osmotic regimes, are considered. At the micro-scale, the REV of clay is comprised of dispersed clay aggregates and partially saturated (variably-sized) spherical pores in between them. At issue, is reconstructing the couplings of mechanical, hydraulic and electrochemical forces at the macroscopic level and their effect on the overall behavior of clay. In Part I, we focus on reversible deformation mechanisms in clay. A generalized nonlinear form of the classical Biot’s poroelasticity relation is obtained with additional terms accounting for capillary and swelling stresses. Capillary stress emerges from interaction of fluid phases at different scales, and takes into account the surface tension effects. The swelling part on the other hand, correlates with the net disjoining hydration and electrochemical forces at the nano-scale. As a result, the stress description of clays is embedded with microstructural information. In addition, a robust localization procedure is utilized to track the microstructural changes associated to micro-porosity and clay platelet spacing. The nonlinearity of the stress–strain description is shown to originate from the dependency of the particles’ elasticity on spacing with electrochemical origins. Finally, base-line features of the model are investigated through material point simulations of a clay swelling test. The discrepancies between the model predictions and experimental measurements are resolved in Part II of this paper by considering also the plastic deformations within the framework developed in Part I.

Probing Selective Adsorption in Cationic-Polymer Induced Aggregation of Binary Anionic Particulate Dispersions Using Solvent Relaxation NMR.

NMR solvent relaxation has been used to characterize the surfaces present in binary anionic particle dispersions, before and after exposure to a cationic polymer. In the polymer-free case, it is shown that the measured specific relaxation rate of the solvent is a population-weighted average of all surfaces present, enabling preferential adsorption to be explored. The addition of the oppositely charged polymer led to phase separation, which was accelerated by gentle centrifugation. The measured relaxation rates and the equilibrium particle concentrations indicate that the cationic hydroxyethylcellulose polymer (HEC LR) exhibited no significant preference for either latex or laponite in binary blends with silica, but a strong preference for TiO2. This study illustrates the versatility of solvent relaxation to probe surface area, surface type and dispersion composition in complex formulations.

Espatial dispersion of the trees in a watershed of Tapalpa, Jalisco

The management of the natural forest represents fundamental ecological, economic and social importance to the residents of theTapalpa mountain, Jalisco. For the best conservation, use and improvement of this forest resource, it seeks to deepen the knowledgeabout the behavior of the structural dynamics of forest masses. The present investigation was carried out through the informationtaken in 71 plots of a systematic sampling, carried out in small watershed of 912 hectares. The objetive was to describe thehorizontal structure, by exploring the pattern of the spatial dispersion of the trees and the tree density of the different stages ofdevelopment, from the youngest to the mature. The Clark and Evans index (I), based on the relationship between the tree-treedistance, was applied in three exercises: general, real and ideal. In the first, by providing a wide range of density, it was posible toobtain the three basic forms of dispersion: random, aggregate and regular. In the second, the aggregate dispersion predominated(96%) as it was the most common in nature. And, the third, based on a proposed density rate, aggregated dispersion also prevailed,which is why it is considered an appropiated perspective to designate silvicultural practices on thinning and regeneration cuts. In anycase, during forest management it is convenient to maintain the same distintive features of the forest, ensuring the spatial dispersionof the trees with Ivalues between 1 and 2.15 for every and each one of the development stages.

Effect of Sulfate on the Aggregation of Clay Particles in Loess

The type and structure of clay minerals are among the main factors affecting the physical and mechanical properties of loess, and the salt content plays a dominant role in many factors affecting aggregation. In this study, the grain size analysis, Atterberg limits tests, scanning electron microscopy (SEM), and energy spectrum analysis (EDS) were used to explore the microstructure and physicochemical mechanisms of the aggregation of clay particles. Finally, the unconfined compressive test, direct shear test, and elastic wave velocity test were conducted to explore the effect of sulfate agglomeration on loess properties. The results show that the salt-washing process leads to the loss of the original soluble salt, dispersion of the original aggregates, and increase of fine particles, such as fine silt and clay. With the increase of sulfate content, the content of fine silt and clay decreases, the liquid limit and plasticity index decrease, the plasticity limit remains unchanged, the aggregate content of fine silt and clay increases, the adsorption capacity weakens, and the diffusion layer compresses and thins. The mechanical test results show that when the sulfate content is less than 3%, the sulfate is almost completely dissolved and the aggregate is less, which increases compressive strength and the cohesion; when the sulfate content is more than 3%, too much sulfate cannot be dissolved and precipitated; hence, the aggregate increases. However, the existence of large volume mirabilite crystals reduces the cementation, which reduces the compressive strength, increases the internal friction angle, and weakens the cohesion.

Effect of humic acid on lysozyme interaction with montmorillonite and kaolinite

Humic acid (HA) as a soil natural organic matter (NOM) can participate in the interaction between proteins and clay minerals, depending on clay type, HA and protein content, and solution conditions. The effect of HA on the interaction of lysozyme (LSZ) with kaolinite (Kao) and montmorillonite (Mont) was investigated at (initial) pHi 5 and 8. In the solutions containing both HA and LSZ, HA/LSZ complexes were formed with a net charge density depending on pH and HA/LSZ mass ratio f. LSZ adsorption on clays in the presence of HA is dominated by adsorption of HA/LSZ complexes. The HA/LSZ mass ratio (fIEP,pHi) at the isoelectric point (IEP) is pH dependent. At f <fIEP,pHi the HA/LSZ complexes are positively charged and adsorb well to the negatively charged Mont and Kao surface fractions. The adsorption levels on Mont are considerably larger than on Kao, which is mainly due to the much larger area fraction of modestly hydrophobic basal plates of Mont. The presence of HA increased the plateau adsorption of LSZ on Kao and Mont for both pHi values, and the LSZ adsorption increased with increasing HA content and pHi values due to a decreasing mutual repulsion of the bound HA/LSZ complexes. At pHi 8 complications arose for low initial LSZ concentrations, for f <fIEP,pHi the HA/LSZ complexes were only weakly positive and formed dispersed aggregates and for f >fIEP,pHi the HA/LSZ complexes were negative, both conditions caused relatively high equilibrium concentrations of LSZ in solution that decreased with increasing initial LSZ concentration. The present results enhance our insight in protein soil interactions for the case that clay particles are brought in contact with aqueous solutions that contain modest amounts of both NOM and protein and stress the importance of the NOM/protein mass ratio and solution pH.

Evaluation of the wound healing effect of neomycin-silver nano-composite gel in rats.

Objectives: Both nano silver and neomycin have wound healing properties. Silver nanoparticles have been used as main compounds for therapeutic drug delivery systems against various ailments. The present study aimed to prepare a neomycin silver nano-composite gel easily, rapidly, and cheaply method to improve wound healing. Methods: Forty-five Wistar rats (150–200 g) divided into nine groups: wound untreated, wound fusidic acid treated, wound neomycin treated, three groups with wound and neomycin silver nano-composite gel at 1:1, 1:2, and 1:3 concentrations, respectively, and three groups wound treated silver nano gel at the previous concentrations, respectively. Percentages of wound healing and histopathological examination of the wound area were assessed in all groups. Results: Atomic force microscopy (AFM) and transmission electron microscopy (TEM) images demonstrated the spherical shape of neomycin silver nano-composite gel without aggregation but homogenous dispersion in a gel matrix. Dynamic light scattering (DLS) showed a 4 nm size of nano silver, which agrees with AFM image data analysis but not with TEM image due to the good coating of the gel matrix to silver nanoparticles. Dynamic light scattering Zeta potential was −21 mV, illustrating the high bioactivity of the neomycin silver nano-composite. The groups receiving neomycin silver nano-composite gel showed a significantly higher and dose dependent wound healing compared to other treatment groups. Conclusion: The present work confirmed the potential wound healing activity of neomycin silver nano-composite gel compared to either alone.

Design of Co-Sn bimetallic nanoalloys as electrocatalyst for alkaline methanol oxidation reaction: Exploring the effect of electroactivation process

The engineering of cost-effective and durable electrocatalysts for the methanol oxidation reaction (MOR) is required for the commercialization of direct methanol fuel cells (DMFCs). Herein, a series of Cox-Sn100-x alloy nanoparticles were synthesized to optimize the Co/S ratio, and the alloy nanoparticle which offered the best electrochemical performance towards MOR was employed as electrocatalyst for further experiments. Moreover, two different electroactivation approaches including i) activation in phosphate buffer medium, and ii) in-situ activation were explored to enlighten their effect on electrochemical characteristics of nanocatalyst. In this regard, the chronoamperometry measurements were carried out at a constant potential over a fixed period of 300 s. Additionally, the pH of the phosphate buffer solution in a range of 3–12, the activation potential ranging −0.7 V to −2.0 V were optimized by evaluating the recorded cyclic voltammograms. Moreover, to predict the effect of phosphate buffer pH in the activation process on the electrocatalytic activity of catalyst were artificial neural network (ANN) approach was implemented. Amongst the various nanoalloys, Co65-Sn35 nanoparticles were determined as the optimal one thanks to their uniform dispersion and less aggregation feature. In the activation process with phosphate buffer at pH of 10 was determined as the optimal, and at this condition a hydrogen evolution reaction also occurred in the range of applied activation potential. The findings revealed that activation in phosphate buffer solution led to the formation of more –OH species, thereby boosting the electrocatalytic activation towards MOR in alkaline media. Similarly, for the in-situ activation approach, the optimum potential was determined as −1.3 V to achieve the maximum current density. The findings offered that the electroactivation in phosphate buffer solution (pH = 10) at −1.3 V could result in a highly active electrocatalyst to be utilized in alkaline DMFCs. This research lays the door for tailoring high-performance, low-cost electrocatalysts that could be used in energy conversion systems instead of commercial noble-metal-based electrocatalysts.

Biofouling of seawater reverse osmosis membranes caused by dispersal of planktonic particulate bacterial aggregates (protobiofilms) from rotary energy recovery devices

A seawater reverse osmosis (SWRO) plant in the Arabian Gulf region showed serious membrane biofouling that appeared to be due to the presence of planktonic particulate bacterial aggregates that can be termed as “protobiofilms”, which possessed the same characteristics of surface-attached biofilms. This SWRO plant utilized dissolved air flotation and ultrafiltration for pretreatment, high permeable SWRO membranes for desalination and incorporated rotary energy recovery devices (RERD). During the first year of operation, a slow steady increase in TMP and channel ∆P was observed that appeared due to membrane biofouling from either colloidal small bacterial aggregates or individual bacterial cells. After the first year of operation, the TMP and channel ∆P increased at an accelerated rate that appeared due presence of planktonic particulate bacterial aggregates. An internal membrane hybridization (IMH) program was initiated after the second year of operation by replacing the two highly fouled high permeable membranes in the feed-end of the pressure vessel with new low permeable membranes to lower the flux and concentration polarization (CP) of the feed-end membranes and to lower the membrane fouling potential. Biofouling of these new low permeable membranes in the IMH program resulted in an immediate and an accelerated increase in both TMP and channel ∆P, which was attributed to the presence of significant concentration of planktonic particulate bacterial aggregates that appeared due to dispersal of a biofilm from the RERD. An important factor that contributed to the dispersal of bacterial aggregates into the RO feed water was the flow velocity through the RERD. Decreasing the flow velocity into and cleaning of the RERD resulted in a significant decrease in the rate of RERD biofilm dispersal and biofilm formation on the SWRO modules.

Distinct roles of the dystrophin-glycoprotein complex: α-dystrobrevin and α-syntrophin in the maintenance of the postsynaptic apparatus of the neuromuscular synapse.

α-syntrophin (α-syn) and α-dystrobrevin (α-dbn), two components of the dystrophin-glycoprotein complex, are essential for the maturation and maintenance of the neuromuscular junction (NMJ) and mice deficient in either α-syn or α-dbn exhibit similar synaptic defects. However, the functional link between these two proteins and whether they exert distinct or redundant functions in the postsynaptic organization of the NMJ remain largely unknown. We generated and analyzed the synaptic phenotype of double heterozygote (α-dbn+/-, α-syn+/-), and double homozygote knockout (α-dbn-/-; α-syn-/-) mice and examined the ability of individual molecules to restore their defects in the synaptic phenotype. We showed that in double heterozygote mice, NMJs have normal synaptic phenotypes and no signs of muscular dystrophy. However, in double knockout mice (α-dbn-/-; α-syn-/-), the synaptic phenotype (the density, the turnover and the distribution of AChRs within synaptic branches) is more severely impaired than in single α-dbn-/- or α-syn-/- mutants. Furthermore, double mutant and single α-dbn-/- mutant mice showed more severe exercise-induced fatigue and more significant reductions in grip strength than single α-syn-/- mutant and wild-type. Finally, we showed that the overexpression of the transgene α-syn-GFP in muscles of double mutant restores primarily the abnormal extensions of membrane containing AChRs that extend beyond synaptic gutters and lack synaptic folds, whereas the overexpression of α-dbn essentially restores the abnormal dispersion of patchy AChR aggregates in the crests of synaptic folds. Altogether, these data suggest that α-syn and α-dbn act in parallel pathways and exert distinct functions on the postsynaptic structural organization of NMJs.

Durable silicon-carbon composites self-assembled from double-protected heterostructure for lithium-ion batteries

HypothesisSilicon-carbon composites have been faced with the contact issues between silicon and carbon in the form of material aggregation and inferior dispersion, leading to electrode cracking or kinetic degradation during cycling. In addition to dispersion improvement from interfacial linkage between self-assembled Si nanoparticles (SiNPs) and carbon fibers (CNFs), the positive influences of high-content carboxymethyl cellulose(CMC) (25 wt%) and amorphous carbon are also expected, respectively after the second-step self-assembly and subsequently sintering. ExperimentsA novel composite (i.e. Si-CNF@C) with the decoration of entire SiNPs in the framework of both CNFs and amorphous carbon was prepared via two-step electrostatic self-assembly followed by sintering. Such a composite with heterogeneous nanostructure was used as a lithium-ion battery anode without additional binders or conductive agents. FindingsSiNPs can be well protected with CNFs and amorphous carbon against the dispersion and contact problems under both effects of electrostatic attraction and chemical bonding. With the double-protected heterostructure, such a novel Si-CNF@C electrode exhibits highly reversible capacities of 1200 mAh g−1, 982 mAh g−1, and 849 mAh g−1 after 100, 500, and 1000 cycles at 0.5 A g−1, respectively. The long-term cycling stability with a capacity loss of 0.036% per cycle over 1000 cycles is comparable.

Chaperones directly and efficiently disperse stress-triggered biomolecular condensates

Stresses such as heat shock trigger the formation of protein aggregates and the induction of a disaggregation system composed of molecular chaperones. Recent work reveals that several cases of apparent heat-induced aggregation, long thought to be the result of toxic misfolding, instead reflect evolved, adaptive biomolecular condensation, with chaperone activity contributing to condensate regulation. Here we show that the yeast disaggregation system directly disperses heat-induced biomolecular condensates of endogenous poly(A)-binding protein (Pab1) orders of magnitude more rapidly than aggregates of the most commonly used misfolded model substrate, firefly luciferase. Beyond its efficiency, heat-induced condensate dispersal differs from heat-induced aggregate dispersal in its molecular requirements and mechanistic behavior. Our work establishes a bona fide endogenous heat-induced substrate for long-studied heat shock proteins, isolates a specific example of chaperone regulation of condensates, and underscores needed expansion of the proteotoxic interpretation of the heat shock response to encompass adaptive, chaperone-mediated regulation.