Mesoscale finite element modelling of failure behaviour of steel-bar reinforced UHPFRC beams with randomly distributed fibres

This study develops a nonlinear finite element model for simulation of complicated failure behaviour of ultra high performance fibre reinforced concrete (UHPFRC) beams reinforced with steel bars and stirrups. In this model, the continuum damage plasticity model is used as the constitutive law for the UHPC matrix, and cohesive elements are used to simulate the softening bond-slip behaviour of the steel fibres/bars-UHPC matrix interfaces. Both the steel fibres and bars are modelled by elastic-plastic beam elements. As such, all the potential failure modes, including the matrix cracking and crushing, yielding and breakage of steel bars and fibres, and debonding of interfaces, can be simulated. A beam under four-point loading with various shear span versus beam depth ratios was simulated to validate the model. The results were compared well with experiments in terms of load-deflection curves and failure behaviour

Effects of material morphology and processing conditions on the characteristics of hydroxyapatite and high-density polyethylene biocomposites by selective laser sintering

Hydroxyapatite (HA), a ceramic to which bone inherently bonds, incorporated into a polymer matrix enhances the bioactivity of implants. In order to rapid-manufacture bioactive implants, selective laser sintering (SLS) has been used to fabricate HA and high-density polyethylene (HDPE) composite (HA-HDPE). The properties of SLS-fabricated specimens have been investigated. The main aspects to be considered in the SLS technology are the properties of the materials used in the process and processing parameters (PPs). HA-HDPE composite specimens have been fabricated using five different powders with variations in particle size (PS), PS distribution, and five different laser PPs. The sintering height, the width, and the shrinkage of the specimens were determined and the effects of the particles and PPs on the physical properties were investigated. The HA-HDPE specimens were found to be highly porous and the sintered density and porosity of the specimens were influenced by the PS and PPs. The interparticle connectivity and the pore size range of the specimens were found to be predominantly determined by the PS and to a lesser extent also influenced by the PPs. The strength of these specimens and the relationship with porosity are discussed

Raman spectroscopy of active-carbon electrodes when Au colloids are placed at the electrolyte/electrode interface

In the past, when Au nanoparticles (AuNPs) were placed just above (but not included in) active carbon (A-C) electrodes, a 10-fold amplification of gravitational specific capacitance were demonstrated, despite the small mass-ratio between the AuNPs and A-C; a ratio of 1:5000. We use surface enhance Raman spectroscopy (SERS) in further studying this system. Supercapacitors are volumetric elements while SERS is a surface interrogating method, whose signal could be impacted by many factors, including local colloid's preferential points (hot spots). Here, we use the ratio between the D- and G-lines of the A-C electrode, ID/IG, as a marker to eliminate the surface inconsistencies. At some concentration levels of AuNPs, the A-C Raman signature shows a clear preference towards the 1600 cm-1 vibration mode (G-line). Following that point, the cell exhibits a large specific capacitance

Relationship between matrix metalloproteinases and the occurrence and development of ovarian cancer

Ovarian cancer is one of the most malignant genital cancers, with a high mortality rate. Many researchers have suggested that matrix metalloproteinases (MMPs) have remarkably high expression in ovarian cancer tissues. MMPs are considered to be related to the occurrence, development, invasion and metastasis of ovarian cancer. Moreover, some studies have discovered that the unbalance between MMPs and tissue inhibitor of metalloproteinases (TIMPs) are associated with the malignant phenotype of tumors. This review summarizes the latest research progress of MMPs in ovarian cancer. The investigation of MMP mechanism in ovarian cancer will facilitate the development of effective anti-tumor drugs, and thereby improve the survival rate of patients with ovarian cancer.</div

Improvement of all-optical Compton γ\gamma-rays source by reshaping colliding pulse

All-optical Compton scattering is a remarkable method of generating high-quality $\gamma$ radiation source. It is easier achieved in experiment by employing a pulse based on laser wakefield accelerator. The driving laser is backward reflected when wakefield acceleration stage is over and thus it naturally collides with energetic electrons. To increase reflected pulse intensity, parabolic focusing plasma mirror instead of flat reflecting target is usually adopted. But concave focusing mirror also deteriorates the emitted photon beam monochromaticity and collimation. We propose using stepped focusing plasma mirror to reflect the driving pulse to conquer these issues. The longitudinal length of reflected pulse by stepped target is larger and intensity is relatively small. It leads emitted photon beam to have better monochromaticity and collimation except for having larger emitted energy and higher laser utilization efficiency. We affirm the robustness of stepped focusing mirror reflecting regime through various kinds of numerical simulations

Electronic Control of Chemistry and Catalysis at the Surface of an Individual Tin Oxide Nanowire

Tin oxide single nanowires configured as field effect transistors were shown to be operable and tunable alternately as gas sensors or as catalysts under a gaseous atmosphere that simulated realistic ambient conditions. The unusually large surface-to-volume ratio available with nanowires causes adsorption or desorption of donor or acceptor molecules on the nanowire's surface to greatly alter its bulk electron density at relatively small values of the gate voltage. This process can be sensitively monitored as changes in the nanowire's conductivity. The potentially radical change in carrier density can lead to significant changes in the nanowire's sensitivity as a sensor or reciprocally as a catalyst in reactions that involve charge exchange across the nanowire's surface. This leads to the prospect of tuning catalysis or other surface reactions entirely through electronic means

Electrochemically Modulated Permeability of Poly(aniline) and Composite Poly(aniline)−Poly(styrenesulfonate) Membranes

The influence of oxidation state on the permeability of several probe molecules through conducting polymer membranes comprising composites of poly(aniline) and poly(styrenesulfonate) was examined in aqueous solution. Pure poly(aniline) membranes displayed a characteristic increase in permeability between reduced and half-oxidized states for neutrally charged phenol and negatively charged 4-hydroxybenzenesulfonate. In contrast, positively charged pyridine experienced decreased permeability through the membrane when poly(aniline) was switched from the reduced to the half-oxidized state. This behavior can be explained by a combination of oxidation-induced film swelling and the anion-exchange character of the positively charged membrane. The membrane composition was modified to include a fixed negative charge by the addition of poly(styrenesulfonate) during synthesis. The incorporation of this negatively charged component introduced cation-exchange character to the film and substantially reduced membrane permeability to 4-hydroxybenzenesulfonate in both oxidation states. In addition, increasing the fraction of poly(styrenesulfonate) in the membrane served to decrease film permeability for all species because of a densification of the membrane. This work demonstrates how both film composition and oxidation state can be used to tune the permeability of conducting polymer membranes

Social capital in a syndicate investment platform - Effects on syndicate lead performance

ABSTRACT Investors on equity crowdfunding platform often face an information asymmetry problem due to the lack of information on assessing the true value of new ventures (Agrawal, Catalini, & Goldfarb, 2016). Moreover, average crowd investors may be either unqualified or unwilling to conduct the requisite due diligence. Equity crowdfunding syndicates emerged in recent years as an innovative form of entrepreneurial financing to overcome these challenges. They serve as a way for “syndicate leads” to leverage their knowledge and bring in substantial funds from a crowd of “backers” (Agrawal et al., 2016). Syndicate leads source investments and secure allocations of funds for investment while conducting due diligence. In exchange, backers pay the syndicate lead a fee (carried interest) for any subsequently profitable investment. This whole process is facilitated on platforms such as AngelList and SyndicateRoom. Despite the growing popularity of equity crowdfunding syndicates, scholarly understanding of the phenomenon is currently limited. Prior research shows equity crowdfunding syndicates shift the focal investment activities of the crowd from startups to syndicate leads (Agrawal et al., 2016). Given the important role played by syndicate leads, it is vital to develop theory-based understandings of their performances. Our study uses social capital theory to examine the effects of syndicate leads’ social capital within and beyond the platform on the performance of syndicate leads. Using data from a sample of 181 syndicate leads on AngelList, a world leading equity crowdfunding platform in the US, our study offers two contributions to social capital literature in the entrepreneurial finance context. First, we differentiate syndicate platform with non-syndicate platform social capital, based on the categories of bonding/internal social capital and bridging/external social capital (Adler & Kwon, 2002). Second, we build upon multidimensional social capital theory and distinguish syndicate leads’ social capital into structural, relational and cognitive aspects (Nahapiet and Ghoshal, 1998). This study represents a first attempt to understand this new form of entrepreneurial financing. We provide a research model with related hypotheses for how syndicate platform multidimensional social capital and non-syndicate platform multidimensional social capital of syndicate leads are related to their performance

sj-tif-3-jdr-10.1177_00220345211051594 – Supplemental material for METTL3-Dependent Glycolysis Regulates Dental Pulp Stem Cell Differentiation

Supplemental material, sj-tif-3-jdr-10.1177_00220345211051594 for METTL3-Dependent Glycolysis Regulates Dental Pulp Stem Cell Differentiation by W. Cai, Y. Ji, L. Han, J. Zhang, Y. Ni, Y. Cheng and Y. Zhang in Journal of Dental Research</p