Surface damages usually occur in concrete structures. In order to restore the functions and prolong the service life of concrete structures, their surface damages should be repaired in time. This ...paper reviews the main requirements for repair materials for concrete structures and the most used inorganic repair materials, such as cement-based materials, alkali-activated materials and polymer modified inorganic repair materials. Moreover, techniques to characterize and even improve the interfaces between these repair materials and concrete substrate are summarized. Cement-based material has the advantages of good mechanical properties and consistency with concrete substrate while having the problems of high shrinkage and low flexibility. Polymer modified materials were found as having lower shrinkage and higher flexural strength. Increasing the roughness or humidity of the surface, adding fibers and applying interfacial agents can improve the bond strength between cement-based repair materials and concrete substrates. All of these repair materials and techniques can help to build a good interfacial bonding, and mechanisms of how they improve the interface are discussed in this article. These are of great importance in guaranteeing the effectiveness of the repair of the concrete surface and to guide the research and development of new repair materials.
Understanding the molecular mechanism of glaucoma and development of neuroprotectants is significantly hindered by the lack of a reliable animal model that accurately recapitulates human glaucoma. ...Here, we sought to develop a mouse model for the secondary glaucoma that is often observed in humans after silicone oil (SO) blocks the pupil or migrates into the anterior chamber following vitreoretinal surgery. We observed significant intraocular pressure (IOP) elevation after intracameral injection of SO, and that SO removal allows IOP to return quickly to normal. This simple, inducible and reversible mouse ocular hypertension model shows dynamic changes of visual function that correlate with progressive retinal ganglion cell (RGC) loss and axon degeneration. It may be applicable with only minor modifications to a range of animal species in which it will generate stable, robust IOP elevation and significant neurodegeneration that will facilitate selection of neuroprotectants and investigating the pathogenesis of ocular hypertension-induced glaucoma.
Therapeutic hypothermia (TH) is potentially an important therapy for central nervous system (CNS) trauma. However, its clinical application remains controversial, hampered by two major factors: (1) ...Many of the CNS injury sites, such as the optic nerve (ON), are deeply buried, preventing access for local TH. The alternative is to apply TH systemically, which significantly limits the applicable temperature range. (2) Even with possible access for 'local refrigeration', cold-induced cellular damage offsets the benefit of TH. Here we present a clinically translatable model of traumatic optic neuropathy (TON) by applying clinical trans-nasal endoscopic surgery to goats and non-human primates. This model faithfully recapitulates clinical features of TON such as the injury site (pre-chiasmatic ON), the spatiotemporal pattern of neural degeneration, and the accessibility of local treatments with large operating space. We also developed a computer program to simplify the endoscopic procedure and expand this model to other large animal species. Moreover, applying a cold-protective treatment, inspired by our previous hibernation research, enables us to deliver deep hypothermia (4 °C) locally to mitigate inflammation and metabolic stress (indicated by the transcriptomic changes after injury) without cold-induced cellular damage, and confers prominent neuroprotection both structurally and functionally. Intriguingly, neither treatment alone was effective, demonstrating that in situ deep hypothermia combined with cold protection constitutes a breakthrough for TH as a therapy for TON and other CNS traumas.
Epitaxy and misfit strain imposed by underlying substrates have been intensively used to tailor the microstructure and electronic properties of oxide films, but this approach is largely restricted by ...commercially limited substrates. In contrast to the conventional epitaxial misfit strains with a positive Poisson’s constant, we show here a tunable Poisson’s ratio with anomalous values from negative, zero, to positive. This permits effective control over the out-of-plane lattice parameters that strongly correlate the magnetic and transport properties in perovskite mixed-valence La1–x Sr x MnO3 thin films. Our results provide an unconventional approach to better modulation and understanding of elastic-mediated microstructures and physical properties of oxide films by engineering the Poisson’s ratios.
Endoplasmic reticulum (ER) stress has been linked with various acute and chronic neurodegenerative diseases. We previously found that optic nerve (ON) injury and diseases induce neuronal ER stress in ...retinal ganglion cells (RGCs). We further demonstrated that germline deletion of CHOP preserves the structure and function of both RGC somata and axons in mouse glaucoma models. Here we report that RGC-specific deletion of CHOP and/or its upstream regulator ATF4 synergistically promotes RGC and ON survival and preserves visual function in mouse ON crush and silicone oil-induced ocular hypertension (SOHU) glaucoma models. Consistently, topical application of the ATF4/CHOP chemical inhibitor ISRIB or RGC-specific CRISPR-mediated knockdown of the ATF4 downstream effector Gadd45a also delivers significant neuroprotection in the SOHU glaucoma model. These studies suggest that blocking the neuronal intrinsic ATF4/CHOP axis of ER stress is a promising neuroprotection strategy for neurodegeneration.
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Hu and colleagues present experimental evidence that neuronal intrinsic blocking of ATF4 and/or CHOP, ATF4 downstream molecule, Gadd45a, and local delivery of an ATF4/CHOP inhibitor, ISRIB, prevent glaucomatous neurodegeneration, indicating a promising neuroprotective gene therapy strategy for retinal ganglion cells in traumatic and glaucomatous optic neuropathies.
It is fundamental to predict or estimate the rheological behavioural evolutions of binders and mixture to ensure a durability service life of the whole infrastructure. This study compared the ...long-term ageing kinetics of hot mix asphalt (HMA) and warm mix asphalt (WMA) produced with the same base bitumen. The difference in the component was that the WMA contained 1% of Cecabase warm agent and 5.5% of water by the weight of bitumen, to obtain a large expansion ratio (47 times). Rolling thin-film oven test (RTFOT) and pressure ageing vessel (PAV) laboratory ageing were carried out on the binder with or without the warm agent. The oven ageing procedure was conducted on the loose HMA and WMA mixtures for 0, 3, 6, and 9 days. Research results indicated that the dual effect of the studied warm agent and the foaming water sharply decreased the viscosity of the binder at a high temperature. Compared with the HMA, the warm agent improved the ageing resistance of the asphalt binder. However, higher content, such as 5.5 wt.%, of foaming water deteriorated viscosity due to a thinner bitumen film, which was more susceptible to oxidation. Therefore, less than 2 wt.% of warm agent and foaming water was recommended in the foamed WMA preparation.
•A model to predict alkali silica reaction (ASR) induced expansion was developed.•The model took into account the influences of different factors on ASR expansion.•Volume of gel was calculated in the ...model by using solid state reaction theory.•Validation of the model shows that the model can predict ASR expansion very well.
This paper proposed a model to predict alkali silica reaction (ASR) induced expansion. The model can estimate the influential factors on ASR expansion, such as the aggregate sizes, mechanical properties of composite materials, and initial alkali concentration. Chemical reactions were described by solid state reaction theory. Concrete was considered to include aggregates, crack region and uncracked region. Alkali silica gel was considered to be the main reason of expansion, and the gel volume was calculated according to the alkali-silica reactions. The model was validated by an experiment of ASR-affected concrete specimens containing glass aggregate. The comparison of calculation results with experimental results showed good applicability of the model.
The topotactic connection style of oxygen octahedron/tetrahedron in transition metal oxides (TMOs) is an important feature that modulates their corresponding physical properties. Using a simple ...chemical doping technique, we obtained Sr
1−
x
Nd
x
CoO
3-
δ
with a crystal structure transition from face-shared octahedron to corner-shared octahedron/tetrahedron. The Rietveld analyses of the X-ray diffraction (XRD) patterns show that the crystal structure changes from rhombohedral to cubic and the connection style transforms from face-shared to corner-shared with the increase neodymium (Nd) content. During this process, the ferromagnetic behavior is greatly improved due to the larger amount of the corner-shared cubic SrCoO
3-δ
phase. The synchrotron radiation X-ray absorption spectroscopies of the Co
L
-edge and O
K
-edge show that Nd-doping mainly affects the electronic structure of oxygen rather than the valence state of Co. Thereby, the Nd changes the connection style of oxygen octahedron/tetrahedron, which then alters the magnetic interactions.
Flavonoids are a large class of polyphenols widely distributed in plants in the free form or as glycosides, and they have antioxidation, antibacterial, antitumor growth, and other pharmacological ...effects. As an important active component of traditional Chinese medicine, they have high medicinal value and development prospects. In this work, the biomolecular properties of 10 common flavonoids, including baicalein, baicalin, apigenin, quercetin, naringenin, hesperetin, daidzein, genistein, puerarin, and gastrodin, are studied by terahertz time-domain spectroscopy (THz-TDS) in the range of 0.2–2.5 THz. The results reveal that these flavonoids have different characteristic absorption peaks in the terahertz band. Moreover, the terahertz absorption characteristics of samples in the temperature range of 78–320 K are studied. The results show that the characteristic absorption peaks gradually increase with the decrease in temperature, and the frequency position of the absorption peak has a slight blue shift. Furthermore, qualitative identification and quantitative analysis of flavonoids are carried out by terahertz spectra combined with chemometrics. Specifically, a series of mixtures of three flavonoids with similar molecular structures under various concentrations are analyzed. The partial least-squares regression (PLSR) model and the artificial neural network (ANN) model are applied to quantitatively analyze the ternary mixture. The results confirm that the ANN model obtains the best predicted value, with the root-mean-square errors in the prediction set (RMSEP) of 1.27% for daidzein. In summary, the biomolecular properties of flavonoids are studied by the THz-TDS technique, and a rapid, effective, and nondestructive method for qualitative identification and quantitative analysis of flavonoids is provided. The results demonstrate that this method has potential application value in the detection of Chinese herbal medicine and has better referential significance for the study of other biomolecules, especially for isomers or similar molecular structures.
Strain has been widely used to manipulate the properties of various kinds of materials, such as ferroelectrics, semiconductors, superconductors, magnetic materials, and "strain engineering" has ...become a very active field. For strain-based information storage, the non-volatile strain is very useful and highly desired. However, in most cases, the strain induced by converse piezoelectric effect is volatile. In this work, we report a non-volatile strain in the (001)-oriented Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals and demonstrate an approach to measure the non-volatile strain. A bipolar loop-like S-E curve is revealed and a mechanism involving 109° ferroelastic domain switching is proposed. The non-volatile high and low strain states should be significant for applications in information storage.
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