Injectable hybrid inorganic nanoscaffold as rapid stem cell assembly template for cartilage repair

Cartilage injuries are often devastating and most cannot be cured because of the intrinsically low regenerative capacity of cartilage tissues. Although stem-cell therapy has shown enormous potential for cartilage repair, the therapeutic outcome has been restricted by low survival rates and poor chondrocyte differentiation in vivo. Here, we report an injectable hybrid inorganic (IHI) nanoscaffold that facilitates fast assembly, enhances survival and regulates chondrogenic differentiation of stem cells. IHI nanoscaffolds that strongly bind to extracellular matrix (ECM) proteins assemble stem cells through synergistic 3D cell–cell and cell–matrix interactions, creating a favorable physical microenvironment for stem-cell survival and differentiation in vitro and in vivo. Additionally, chondrogenic factors can be loaded into nanoscaffolds with a high capacity, which allows deep, homogenous drug delivery into assembled 3D stem-cell-derived tissues for effective control over the soluble microenvironment of stem cells. The developed IHI nanoscaffolds that assemble with stem cells are injectable. They also scavenge reactive oxygen species and timely biodegrade for proper integration into injured cartilage tissues. Implantation of stem-cell-assembled IHI nanoscaffolds into injured cartilage results in accelerated tissue regeneration and functional recovery. By establishing our IHI nanoscaffold-templated 3D stem-cell assembly method, we provide a promising approach to better overcoming the inhibitory microenvironment associated with cartilage injuries and to advance current stem-cell-based tissue engineering.     

An electrostatic microwell–based biochip for phytoplanktonic cell trapping

A simple microwell-based microfluidic chip for microalgal cells trapping was fabricated. An electrostatic cell trapping mechanism, enabled by a positively charged glass surface, was used. The chip was capable of capturing multiple algal cell types. In the case of filamentous Spirulina platensis, we observed single filament occupancy of up to ∼30% available wells, as high as some previously proposed methods. Captured filaments were not of any preferential size, suggesting well randomized cell trapping. It was found that the electrostatic attraction did not affect the cell growth. Total replacement of liquid inside the wells could be achieved by pumping new solutions via the inlet, making single cell experiments in controlled chemical conditions possible. After the top layer of the chip was removed, cells in the wells could be simply transferred using a micropipette, turning the chip into a platform for strain selection.     

刺五加的有性生殖与营养繁殖

刺五加 Eleutherococcus senticosus (Rupr.et Maxim.)Maxim,既可进行有性繁殖,又可进行营养繁殖。本文报道其三类花丝长度不同的植株每个花序的花朵数量、座果率、饱满种子率及根茎形态和形态发生的某些特点。通过人工受精,检测了其繁育系统。结果表明:长花丝植株不座果,短花丝植株座果,但不同年份、不同生境中座果率不同,中花丝植株也座果但饱满种子率教低。在正常年份,短花丝植株的座果率接近40％，并且林缘的座果率稍高于皆伐迹地和次生林下的。考虑到中花丝植株在所研究地区居群数很少，我们认为绝大多数刺五加种子是异花传粉的产物，其有性生殖与营养繁殖相配合，在无人为破坏的前提下，该物种不应该濒危。     

Photosystem II-based biomimetic assembly for enhanced photosynthesis

Photosystem II (PSII) is a fascinating photosynthesis-involved enzyme, participating in sunlight-harvest, water splitting, oxygen release, and proton/electron generation and transfer. Scientists have been inspired to couple PSII with synthetic hierarchical structures via biomimetic assembly, facilitating attainment of natural photosynthesis processes, such as photocatalytic water splitting, electron transfer and ATP synthesis, in vivo. In the past decade, there has been significant progress in PSII-based biomimetic systems, such as artificial chloroplasts and photoelectrochemical cells. The biomimetic assembly approach helps PSII gather functions and properties from synthetic materials, resulting in a complex with partly natural and partly synthetic components. PSII-based biomimetic assembly offers opportunities to forward semi-biohybrid research and synchronously inspire optimization of artificial light-harvest micro/nanodevices. This review summarizes recent studies on how PSII combines with artificial structures via molecular assembly and highlights PSII-based semi-natural biosystems which arise from synthetic parts and natural components. Moreover, we discuss the challenges and remaining problems for PSII-based systems and the outlook for their development and applications. We believe this topic provides inspiration for rational designs to develop biomimetic PSII-based semi-natural devices and further reveal the secrets of energy conversion within natural photosynthesis from the molecular level.     

Salvinia-like slippery surface with stable and mobile water/air contact line

Superhydrophobic surfaces are widely used in many industrial settings, and mainly consist of rough solid protrusions that entrap air to minimize the liquid/solid area. The stability of the superhydrophobic state favors relatively small spacing between protrusions. However, this in turn increases the lateral adhesion force that retards the mobility of drops. Here we propose a novel approach that optimizes both properties simultaneously. Inspired by the hydrophobic leaves of Salvinia molesta and the slippery Nepenthes pitcher plants, we designed a Salvinia-like slippery surface (SSS) consisting of protrusions with slippery heads. We demonstrate that compared to a control surface, the SSS exhibits increased stability against pressure and impact, and enhanced lateral mobility of water drops as well as reduced hydrodynamic drag. We also systematically investigate the wetting dynamics on the SSS. With its easy fabrication and enhanced performance, we envision that SSS will be useful in a variety of fields in industry.     

分子伴侣与蛋白质折叠

新合成的多肽链必须先经折叠和装配后形成特定的三维结构才具有活性．在多肽链折叠过程中，往往会产生折叠异常蛋白，形成集聚体．分子伴侣可有效地调控多肽链的正确折叠，从而避免集聚体的形成．文章主要对分子伴侣的定义、作用、种类、特性等做一介绍。     

Toward incorporating a task-stage identification technique into the long-term document support process

Effective knowledge management in a knowledge-intensive environment can place heavy demands on the information filtering (IF) strategies used to model workers’ long-term task-needs. Because of the growing complexity of knowledge-intensive work tasks, a profiling technique is needed to deliver task-relevant documents to workers. In this study, we propose an IF technique with task-stage identification that provides effective codification-based support throughout the execution of a task. Task-needs pattern similarity analysis based on a correlation value is used to identify a worker’s task-stage (the pre-focus, focus formulation, or post-focus task-stage). The identified task-stage is then incorporated into a profile adaptation process to generate the worker’s current task profile. The results of a pilot study conducted in a research institute confirm that there is a low or negative correlation between search sessions and transactions in the pre-focus task-stage, whereas there is at least a moderate correlation between search sessions/transactions in the post-focus stage. Compared with the traditional IF technique, the proposed IF technique with task-stage identification achieves, on average, a 19.49% improvement in task-relevant document support. The results confirm the effectiveness of the proposed method for knowledge-intensive work tasks.     

A microfluidic co-culture system to monitor tumor-stromal interactions on a chip

The living cells are arranged in a complex natural environment wherein they interact with extracellular matrix and other neighboring cells. Cell-cell interactions, especially those between distinct phenotypes, have attracted particular interest due to the significant physiological relevance they can reveal for both fundamental and applied biomedical research. To study cell-cell interactions, it is necessary to develop co-culture systems, where different cell types can be cultured within the same confined space. Although the current advancement in lab-on-a-chip technology has allowed the creation of in vitro models to mimic the complexity of in vivo environment, it is still rather challenging to create such co-culture systems for easy control of different colonies of cells. In this paper, we have demonstrated a straightforward method for the development of an on-chip co-culture system. It involves a series of steps to selectively change the surface property for discriminative cell seeding and to induce cellular interaction in a co-culture region. Bone marrow stromal cells (HS5) and a liver tumor cell line (HuH7) have been used to demonstrate this co-culture model. The cell migration and cellular interaction have been analyzed using microscopy and biochemical assays. This co-culture system could be used as a disease model to obtain biological insight of pathological progression, as well as a tool to evaluate the efficacy of different drugs for pharmaceutical studies.     

Electrical Conductivity as a Tool to Detect Salt in Clinical Proteomics Samples

Clinical proteomics encompasses the study of the proteins in the human body at different settings to understand the various physiological and pathological pathways. The processing of the samples for electrophoresis based proteomics is a challenge to any researcher. Salt in particular can have an array of effects during the electrophoretic separation of proteins. There is a definite need to determine the concentration of salts in the samples and the effectiveness of salt removing protocols on small volume samples. A simple-cost effective technique to know the salt concentration in the clinical proteomics samples has been highlighted in the report. The application will be of value in a developing country such as India.     

Isolation ofMycobacterium Tuberculosis 31 kDa antigen protein of diagnostic interest from culture filtrate using anti-ES-31 antibody by affinity chromatography

Proteins secreted into the culture medium byMycobacterium tuberculosis (M. tb) are shown to be source of antigens of immunodiagnostic interest. Anin vitro released 31 kDa antigen ESAS-7F isolated fromM.tb H₃₇Ra culture filtrate by salt precipitation, SDS-PAGE and cation exchange fast protein liquid chromatography (FPLC) was shown earlier to be a diagnostically important antigen fraction. In this report, we describe the isolation of ESAS-7F antigen using monospecific antibody coupled to sepharose CL-4B column. The percentage recovery of ESAS-7F antigen using affinity chromatography was approximately 8% of the total ES antigen proteins compared to 0.05% obtained by conventional purification steps using salt precipitation, SDS-PAGE and FPLC. Similar seroreactivity was observed by the antigen isolated by both the methods in indirect ELISA. Affinity chromatography helped in an increased recovery of ESAS-7F antigen and obviates the need for time consuming conventional purification steps.     

Thoriated tungsten filaments

The rate of evaporation of electrons, ν_e, from a thoriated tungsten filament depends on the temperature T and on θ, the fraction of the surface covered by thorium atoms. The relation of ν_e to θ and T has been given by Brattain and Becker. From ν_e the change in contact potential V of the filament surface produced by the adsorbed thorium can be calculated by the Boltzmann equation. Knowing σ the number of thorium atoms per cm.³, the dipole moment M of each is given by V = 2τσM. By an equation already used for Cs films on tungsten, the 2-dimensional equation of state of the adsorbed film can be calculated from M. Then by Gibbs' adsorption equation the relation of the atom evaporation rate ν_a to θ and T can be determined. It is thus calculated that in the range from θ = 0.2 to θ = 0.6, ν_a varies in proportion to ?^Hθ where H = 8.1 in good agreement with the value H = 7.8 given by Brattain and Becker's measurements. A recalculation of the data of numerous experiments in 1921–1923, using the new relations of ν_e to θ₁ gives data on ν_a as a function of T and θ in good agreement with the values of ν_a calculated from ν_e.The diffusion coefficients of Th through tungsten crystals, along grain boundaries and over the free filament surface, are calculated. A theory is given for the cause of the variation in the surface diffusion coefficient with σ. The probable mechanism of the production of the metallic thorium within the filament is discussed. At 2400° the thorium which arrives at the surface along grain boundaries, for some unknown reason, does not spread out over the surface as it does at lower temperatures (1900–2100°).     

Analyzing shear stress-induced alignment of actin filaments in endothelial cells with a microfluidic assay

The physiology of vascular endothelial cells is strongly affected by fluid shear stress on their surface. In this study, a microfluidic assay was employed to analyze the alignment of actin filaments in endothelial cells in response to shear stress. When cells were cultured in microfluidic channels and subjected to shear stress, the alignment of filaments in the channel direction was significantly higher than in static cultures. By adding inhibitory drugs, the roles of several signaling proteins in the process of alignment were determined. Thus, it is shown how microfluidic technology can be employed to provide a mechanistic insight into cell physiology.     

De novo assembly of a Tibetan genome and identification of novel structural variants associated with high-altitude adaptation

Structural variants (SVs) may play important roles in human adaptation to extreme environments such as high altitude but have been under-investigated. Here, combining long-read sequencing with multiple scaffolding techniques, we assembled a high-quality Tibetan genome (ZF1), with a contig N50 length of 24.57 mega-base pairs (Mb) and a scaffold N50 length of 58.80 Mb. The ZF1 assembly filled 80 remaining N-gaps (0.25 Mb in total length) in the reference human genome (GRCh38). Markedly, we detected 17 900 SVs, among which the ZF1-specific SVs are enriched in GTPase activity that is required for activation of the hypoxic pathway. Further population analysis uncovered a 163-bp intronic deletion in the MKL1 gene showing large divergence between highland Tibetans and lowland Han Chinese. This deletion is significantly associated with lower systolic pulmonary arterial pressure, one of the key adaptive physiological traits in Tibetans. Moreover, with the use of the high-quality de novo assembly, we observed a much higher rate of genome-wide archaic hominid (Altai Neanderthal and Denisovan) shared non-reference sequences in ZF1 (1.32%–1.53%) compared to other East Asian genomes (0.70%–0.98%), reflecting a unique genomic composition of Tibetans. One such archaic hominid shared sequence—a 662-bp intronic insertion in the SCUBE2 gene—is enriched and associated with better lung function (the FEV1/FVC ratio) in Tibetans. Collectively, we generated the first high-resolution Tibetan reference genome, and the identified SVs may serve as valuable resources for future evolutionary and medical studies.     

Using searcher simulations to redesign a polyrepresentative implicit feedback interface

Information seeking is traditionally conducted in environments where search results are represented at the user interface by a minimal amount of meta-information such as titles and query-based summaries. The goal of this form of presentation is to give searchers sufficient context to help them make informed interaction decisions without overloading them cognitively. The principle of polyrepresentation [Ingwersen, P. (1996). Cognitive perspectives of information retrieval interaction: elements of a cognitive IR theory. Journal of Documentation 52, 3–50] suggests that information retrieval (IR) systems should provide and use different cognitive structures during acts of communication to reduce the uncertainty associated with interactive IR. In previous work we have created content-rich search interfaces that implement an aspect of polyrepresentative theory, and are capable of displaying multiple representations of the retrieved documents simultaneously at the results interface. Searcher interaction with content-rich interfaces was used as implicit relevance feedback (IRF) to construct modified queries. These interfaces have been shown to be successful in experimentation with human subjects but we do not know whether the information was presented in a way that makes good use of the display space, or positioned most useful components in easily accessible locations, for use in IRF. In this article we use simulations of searcher interaction behaviour as design tools to determine the most rational interface design for when IRF is employed. This research forms part of the iterative design of interfaces to proactively support searchers.     

我国西沙群岛海藻的研究I．殖丝藻属

The reproductive feature of the nemalionalean genus Liagora is characterized by the laterally situated carpogonial branch which is produced by the ordinarily assi- milative filament.  A study of L. farinosa Lamx. has revealed that the carpogonial branches of this species are not borne on the  ordinarily  assimilative  filaments  but restricted to a kind of short filaments (referring to as “fertile filaments”  in the present article) which are, in turn, initiated by the basal cells of the assimilative filaments.  The carpogonial branches are modified furcations of the fertile filaments. The fertile filaments may, however, grow and send out assimilative filaments concur- rently with the maturation of the carpogonial branches.  Therefore, the origin of the carpogonial branches is best shown in their younger developing stages but more or less obscure in age.      Boergesen, who examined Lamouroux's type, made a detailed study of L. farinosa from the Canary Islands.  The depictions given by Boergesen, Yamada (1938, f. 15), Tseng (1941, f. 6) and Umezaki (1961, f. lA) concisely illustrated the feature of the fertile filaments in this species, although all these workers had not envisaged the taxonomical significance of the peculiar position of the female organs.  In our opin- ion, the differentiation of cortical filaments into assimilative and reproductive as seen in L. farinosa (even though in a preliminary stage)  suggests that the progressive evolutionary changes have occurred in this species.  The unique situation of L. fari- nosa is, in fact, no parallel in any genus of the, family where female organs are directly produced (or transformed) by the assimilative filaments.       It thus appears there is no justification for retaining L. farinosa in the genus Liagora.  A new genus, Ganonema Fan et Wang gen. nov. is therefore proposedfor accommodating the species, G. farinosa (Lamx.) Fan et Wang comb. nov.     

Diatom-inspired multiscale mineralization of patterned protein–polysaccharide complex structures

Marine diatoms construct their hierarchically ordered, three-dimensional (3D) external structures called frustules through precise biomineralization processes. Recapitulating the remarkable architectures and functions of diatom frustules in artificial materials is a major challenge that has important technological implications for hierarchically ordered composites. Here, we report the construction of highly ordered, mineralized composites based on fabrication of complex self-supporting porous structures—made of genetically engineered amyloid fusion proteins and the natural polysaccharide chitin—and performing in situ multiscale protein-mediated mineralization with diverse inorganic materials, including SiO₂, TiO₂ and Ga₂O₃. Subsequently, using sugar cubes as templates, we demonstrate that 3D fabricated porous structures can become colonized by engineered bacteria and can be functionalized with highly photoreactive minerals, thereby enabling co-localization of the photocatalytic units with a bacteria-based hydrogenase reaction for a successful semi-solid artificial photosynthesis system for hydrogen evolution. Our study thus highlights the power of coupling genetically engineered proteins and polysaccharides with biofabrication techniques to generate hierarchically organized mineralized porous structures inspired by nature.     

Sin1-mediated mTOR signaling in cell growth,metabolism and immune response

The mammalian target of rapamycin (mTOR) is an evolutionarily conserved Ser/Thr protein kinase with essential cellular function via processing various extracellular and intracellular inputs. Two distinct multi-protein mTOR complexes (mTORC), mTORC1 and mTORC2, have been identified and well characterized in eukaryotic cells from yeast to human. Sin1, which stands for Sty1/Spc1-interacting protein1, also known as mitogen-activated protein kinase (MAPK) associated protein (MAPKAP)1, is an evolutionarily conserved adaptor protein. Mammalian Sin1 interacts with many cellular proteins, but it has been widely studied as an essential component of mTORC2, and it is crucial not only for the assembly of mTORC2 but also for the regulation of its substrate specificity. In this review, we summarize our current knowledge of the structure and functions of Sin1, focusing specifically on its protein interaction network and its roles in the mTOR pathway that could account for various cellular functions of mTOR in growth, metabolism, immunity and cancer.     

Novel method of generating water-in-oil(W∕O) droplets in a microchannel with grooved walls

We present a novel method of generating and retrieving droplets stored in microfluidic grooves or cavity structures. First we designed and fabricated polydimethylsiloxane microchannels with grooves on the walls and then produced a two-phase flow of oil and aqueous phases to form aqueous phase droplets in an oil state. We propose the following three mechanisms of droplet generation: the contact line on the groove wall continues moving along the wall and descends to the bottom of the cavity, confining the aqueous phase in the cavity; once the interface between the oil and aqueous phases moves into the cavity, the interface contacts the top of the neighboring groove; and a spherical droplet forms at the corner in the cavity due to surface tension. The viscosity of the oil phase and the surface tension of the interface determine whether a droplet can be generated. Then, we could adjust the velocity of the interface and the aspect ratio of the cavity to achieve the optimal conditions for generating the single droplet. We observed that the largest droplet is stably generated without a daughter droplet at typical values of free-stream velocity (10 μl∕min) and groove pitch 110 μm for all three cases with different oil phases (20, 50, and 84 cP). This technique is expected to serve as a platform for droplet-based reaction systems, particularly with regard to monitoring cell behavior, in vitro expression, and possibly even micropolymerase chain reaction chambers.     

基于SolidWorks的虚拟设备拆装系统研究

设备拆装实训是机电一体化专业人才培养当中的一项重要的实践教学环节,基于虚拟现实技术的机电设备拆装实训系统具有良好的交互性和较强的沉浸感,可以为实物拆装实训教学提供必要的准备和补充。提出并设计了一种基于SolidWorks的虚拟设备拆装系统,为设计和开发基于虚拟现实技术的实训教学系统给出有益的参考。