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Hydrogels prepared from poly(ethylene glycol) (PEG) are widely applied in tissue engineering, especially those derived from a combination of functional multi-arm star PEG and linear crosslinker, with an expectation to form a structurally ideal network. However, the poor mechanical strength still renders their further applications. Here we examined the relationship between the dynamics of the pre-gel solution and the mechanical property of the resultant hydrogel in a system consisting of 4-arm star PEG functionalized with vinyl sulfone and short dithiol crosslinker. A method to prepare mechanically strong hydrogel for cartilage tissue engineering is proposed. It is found that when gelation takes place at the overlap concentration, at which a slow relaxation mode just appears in dynamic light scattering (DLS), the resultant hydrogel has a local maximum compressive strength ∼20 MPa, while still keeps ultralow mass concentration and Young's modulus. Chondrocyte-laden hydrogel constructed under this condition was transplanted into the subcutaneous pocket and an osteochondral defect model in SCID mice. The in vivo results show that chondrocytes can proliferate and maintain their phenotypes in the hydrogel, with the production of abundant extracellular matrix (ECM) components, formation of typical chondrocyte lacunae structure and increase in Young's modulus over 12 weeks, as indicated by histological, immunohistochemistry, gene expression analyses and mechanical test. Moreover, newly formed hyaline cartilage was observed to be integrated with the host articular cartilage tissue in the defects injected with chondrocytes/hydrogel constructs. The results suggest that this hydrogel is a promising candidate scaffold for cartilage tissue engineering. [ABSTRACT FROM AUTHOR]

Abstract: The thermal degradation of ethylene–butyl acrylate (EBA) copolymer with/without CaCO3 has been studied via the combined TGA-FTIR technique at a heating rate of 10°C/min in high purified N2. The volatiles from EBA on heating include mainly 1-alkene (i.e. 1-butene), hydrocarbon chain fragments, CO2, butyl acrylate-containing fragment, as well as the trace of CO and H2O in the temperature range of 350–500°C. The 1-butene is most likely formed through ester pyrolysis. The two bands at 2925cm−1 (asymmetric stretching of –CH 2 –, corresponding to hydrocarbon chain fragments), and 720cm−1 (plane rocking of –CH2–, representative of the alkanes with low molecular weight –(CH2) n –, n ≥4) were indicative of the hydrocarbon species essentially accompanied with acrylate-containing fragments at high temperature. Based on the data message of the TGA and the Gram–Schmidt curves, it shows that the EBA copolymer becomes much more stable in the presence of CaCO3. The volatiles involved in the pyrolysis of EBA copolymer have qualitatively chemical composition similar to the case with CaCO3. Obviously, both the descending flammable volatiles and the ascending creation in CO2 from EBA copolymer do come intimately from the interposition of CaCO3. That both the prolonged ignition time and the reduced heat release rate of EBA during combustion depend, therefore, on the presence of CaCO3 is being expected. [Copyright &y& Elsevier]

XPS studies have been undertaken on exfoliated nanocomposites of polystyrene and poly(methyl methacrylate). One can clearly see that carbon is lost and that oxygen, silicon and aluminum accumulate at the surface of the degrading polymer. The concentration of aluminum at the surface is very low at the beginning of the experiment but makes a large jump at the same temperature at which carbon is lost and oxygen begins to accumulate at the surface. It appears that the ratio of silicon to aluminum changes as the polymer is lost. A brief discussion is given to explain the origin of oxygen at the surface. [Copyright &y& Elsevier]

X-ray photoelectron spectroscopy, XPS, has been used to examine several polystyrene-clay nanocomposites. The accumulation of oxygen, from the almuniosilicate, on the surface of the polymer was observed, along with the loss of carbon. This confirms that the barrier properties of the clay provide a mechanism by which nanocomposite formation can enhance the fire retardancy of the polymers. No difference is detected depending upon the extent of exfoliation or intercalation of the nanocomposite. [Copyright &y& Elsevier]

Chronic periodontitis is an inflammatory disease that represents a major public health issue nowadays. Here, we investigated the protective role of nuclear factor kappa B (NF-κB) inducing kinase (NIK)-inhibitor on chronic periodontitis and revealed the underlying molecular mechanism. NIK-inhibitor was synthesized, and its functions were examined in primary osteoclasts and wild-type (WT) and NIK-/- chronic periodontitis mouse model. Lipopolysaccharides (LPS) or activator of NF-κB was applied to stimulate inflammatory response of osteoclasts. The qRT-PCR, ELISA and Western blot were used to measure the expression of pro-inflammatory and osteoclast-related genes, and the activation of NF-κB signaling. Osteoclastogenesis and bone damage were detected by TRAP staining and micro-CT. NIK knockdown mice had lower expression of osteoclast-related genes and improved CEJ-ABC damage. Similarly, NIK-inhibitor administration inhibited inflammatory responses and CEJ-ABC damage in chronic periodontitis models. NIK-inhibitor suppressed osteoclastogenesis and osteoclast-related genes expression through inhibiting the non-canonical NF-κB signaling. NIK plays important role in bone destruction of chronic periodontitis and NIK-inhibitor represents a promising therapeutic strategy for this disease. [ABSTRACT FROM AUTHOR]

River ecosystems are under increasing stress in the background of global change and ever-growing anthropogenic impacts in Central Asia. However, available water quality data in this region are insufficient for a reliable assessment of the current status, which come as no surprise that the limited knowledge of regulating processes for further prediction of solute variations hinders the development of sustainable management strategies. Here, we analyzed a dataset of various water quality variables from two sampling campaigns in 2019 in the catchments of two major rivers in Central Asia—the Amu Darya and Syr Darya Rivers. Our results suggested high spatial heterogeneity of salinity and major ion components along the longitudinal directions in both river catchments, pointing to an increasing influence of human activities toward downstream areas. We linked the modeling outputs from the global nutrient model (IMAGE-GNM) to riverine nutrients to elucidate the effect of different natural and anthropogenic sources in dictating the longitudinal variations of the riverine nutrient concentrations (N and P). Diffuse nutrient loadings dominated the export flux into the rivers, whereas leaching and surface runoff constituted the major fractions for N and P, respectively. Discharge of agricultural irrigation water into the rivers was the major cause of the increases in nutrients and salinity. Given that the conditions in Central Asia are highly susceptible to climate change, our findings call for more efforts to establish holistic management of water quality. [Display omitted] • We provide the dataset in two Central Asian rivers addressing salinity and nutrients. • Causal relationship between nutrient sources and concentrations was established. • Longitudinal variations of nutrients and salinity were driven by irrigated croplands. • N from leaching and P from surface runoff dominated in the export flux to the rivers. [ABSTRACT FROM AUTHOR]

The ammonium sulphate ((NH 4) 2 SO 4) in-situ leaching process is the most widely used extraction technology for weathered crust elution-deposited rare earth ores (WCED-REOs). Highly concentrated (NH 4) 2 SO 4 , a representative leaching agent, is often used in the leaching process of WCED-REOs. However, this in-situ leaching process causes nitrogen pollution in the soil, surrounding surface and ground water due to the high concentrations of (NH 4) 2 SO 4 solutions used as a long term leaching agent. To date, the mechanism behind the variations in ammonia nitrogen (AN) in deep soil profiles is unclear. We conducted vertical and lateral soil sampling and analyzed the collected samples for soil moisture, pH, ammonia forms, and AN contents in soil profiles deeper than 500 cm in an in-situ leaching mining area of Ganzhou, Jiangxi Province, southern China. The results show that primary chemical pollutants in the soil are derived from residual leaching agents with high acidities and concentrations of AN. Twelve years after the mining process was completed, the mean pH values of the tailings in the mining area were 3.90 and 4.87 in its lower reaches. Due to the presence of chemical residues, the AN concentration was 12–40 times higher than that of the raw ore soil before it was mined. The percentages of different ammonium forms in the rare earth tailing soil were 65%, 30%, and 5% for the water-soluble, exchangeable, and fixed ammonium forms, respectively. The results of this study support effective prevention and remediation treatment of environmental problems caused by AN pollution of the soil in WCED-REOs. Image 1 • Ammonia nitrogen (AN) pollution and acidification are serious along deep soil profiles in the WCED-REOs. • Spatial patterns of AN and pH were first released in the polluted tailing. • Percentage of different forms of ammonium were first quantified in tailing soils. • Adsorption and desorption process of ammonia nitrogen were revealed in tailing soils. Main finding: This study obtained spatial patterns of ammonia nitrogen, percentages of the different forms of ammonia nitrogen, and the pH impact on the polluted WCED-REOs. [ABSTRACT FROM AUTHOR]

The C f /SiBCN–ZrB 2 composites were prepared by dipping and winding combined with reactive hot pressing. The flexural strength and fracture toughness reached 261 MPa and 11.96 MPa • m1/2, respectively, through continuous carbon fibers debonding, pulling and bridging mechanisms. Excellent mechanical properties ensured that the C f /SiBCN–ZrB 2 composites remained intact after exposure to a plasma flame with a heat flux of 9.37 MW/m2 for 300 s, with the mass and linear ablation rates of 1.78 mg/s, 1.01 μm/s, respectively. The excellent ablation resistance was due to the formation of dense oxide layers separating the matrix from the plasma flame. The SiO 2 formed in the low-temperature areas away from the center was the main ablation-resistant barrier, while the ZrO 2 /SiO 2 double oxide layer formed in the high-temperature region at the center was the major ablation-resistant barrier. [ABSTRACT FROM AUTHOR]

Surface active agents are often used to improve dispersion of nanoparticles. Quantitative correlation between these surface-active molecules and nanoscale dispersion is absent from the literature partly because a quantitative measure of nanoscale dispersion does not exist. Recently, we have developed the Virial-van der Waals method to quantify dispersion in nanocomposites using virial coefficients. In this paper, the Langmuir adsorption model is used to quantify the influence of surface-active agents on nano-scale dispersion in terms of the effective second virial coefficient B 2 ∗. The impact of silane coupling agent on the nano-dispersion and silica aggregate structure in precipitated silica/SBR nanocomposites is demonstrated. It is shown that the higher viscosity SBR matrix led to a greater silica aggregate structural breakup, while lower viscosity matrix improved surface silanization. The isomeric content of the SBR, which impacts the dielectric behavior, impacted whether the system could be modeled through a mean-field or specific interactions. We earlier showed that larger aggregates improve dispersion, and this is reaffirmed in these results. After account is made for aggregate size, nano-scale dispersion improves with the addition of silane coupling agent. The behavior is well modeled using Langmuir monolayer adsorption. [Display omitted] • Correlation of surface-active agent concentration and nanoscale dispersion. • Virial-van der Waals kinetic mixing model. • Langmuir absorption model for second virial coefficient as a measure of dispersion. • Distinction between mean-field and specific interactions. • Debye charge screening in polymer nanocomposites. [ABSTRACT FROM AUTHOR]

• Adrenergic receptors expression of uterine stroma increased during early pregnancy. • Adverse pregnancy outcomes due to exogenous epinephrine exposure in post-implantation mice. • Epinephrine exposure during early pregnancy resulted in decidualization defect. • Epinephrine exposure impaired uterine decidualization independent of embryo development. Our understanding of the relationship between stress-derived epinephrine and early pregnancy failure remains incomplete. Here, we explored the effect of epinephrine exposure on early pregnancy and pseudopregnancy in mice. Increased expression of adrenergic receptors Adra1b, Adra2b and Adrb2 was observed during decidualization and post-implantation embryogenesis was delayed or survival impaired. Epinephrine treatment also impaired decidualization in both the gravid and pseudopregnant uterus, suggesting the effect on decidualization was independent of the conceptus. This included a suppression of endometrial stroma cell proliferation and of key decidualization regulators, including COX2, BMP2 and WNT4. Collectively, these data demonstrate that maternal epinephrine exposure during early pregnancy impairs uterine decidualization and embryo development, underlying early pregnancy failure. [ABSTRACT FROM AUTHOR]

Radar-based life imaging technology has been widely applied in both civilian and military applications. Wall penetration attenuation degrades the signal-to-clutter-and-noise ratio (SCNR) and radar portability restricts the spatial resolution of the high-dimensional image. In this study, we constructed a portable linear-frequency continuous-wave (LFMCW) multiple-input multiple-output (MIMO) radar system, and we presented a novel high-dimensional imaging framework. We combined the maximum spectrum peak, fourth-order cumulant (FOC) and 3D coherent factor (CF) to enhance vital signs based on attention mechanism. We improve resolution by deconvolution algorithm using the data from a human dummy. Visualization-enhanced 4D point clouds images were created by mapping micro-doppler-frequency to color. We employed a series of experiments to validate the proposed method, including human and beagle imaging in free space, and short-range and long-range (16 m) human imaging through a wall. These high-dimensional imaging results validated the portable radar system's potential in detection, identification, interpretation of human targets. [ABSTRACT FROM AUTHOR]

Abstract: Hydrothermally altered rocks are products of fluid–rock interactions, and typically preserve numerous quartz veins that formed as chemical precipitates from fluids that fill up cracks. Thus, quartz veins are the record of the fluid system that involved fracture flow in the direction of changing temperature or pressure. In order to decipher the fluid activity in the Sulu ultrahigh-pressure (UHP) terrane in eastern China, quartz veins together with an adjacent eclogite lens and the host gneiss were studied. In one location a deformed quartz vein is located at the boundary between the host gneiss and the eclogite lens. The amphibolite-facies overprinting of the eclogite lens decreases from the rim to the core of the lens, with fresh eclogite preserved in the core. The foliated biotite gneiss contains felsic veins and residual phengites. Zircon rims from the gneiss are characterized by melt-related signatures with steep HREE patterns, high Hf contents and negative Eu anomalies, and a pool of weighted average 206Pb/238U analyses reveal an age of 219±3Ma (2σ), which is younger than the UHP metamorphic age (236±2Ma, 2σ) recorded by zircons from the eclogite lens. This suggests that the gneiss in the Sulu UHP terrane could have suffered from partial melting due to phengite dehydration during the “hot” exhumation stage. The formation age of the quartz vein (219±2Ma, 2σ) defined by zircon rims agrees well with the partial melting time (219±3Ma, 2σ) of the host gneiss. The initial 176Hf/177Hf ratios of zircon rims from the quartz vein are obviously lower than zircons from the eclogite lens, but overlap with the coeval zircon domains from the nearby granite dikes produced by partial melting of orthogneiss. These observations suggest that the quartz vein and corresponding fluid flow could be associated with partial melting of the host gneiss. On the other hand, amphibole-bearing and HREE-rich zircon rims from the amphibolite pool an amphibolite-facies metamorphic age of 217±5Ma (2σ), overlap with the formation age of the quartz vein. This implies that retrogression of the eclogite lens could have been caused by melting-induced fluid flow. Based on the above observations, we speculate that partial melting of the gneiss in the continental subduction-related UHP belt could have induced a significant fluid flow during the exhumation stage, and thus contributed significantly to the extensive retrogression of eclogites in the Sulu UHP terrane. [Copyright &y& Elsevier]

Abstract: Clastic sedimentary rocks are samples of the exposed continental crust. In order to characterize the crustal growth history of North China and its possible regional variations, 479 concordant detrital zircons in three sand samples from the lower reach of the Yellow River (which drains the Tibet–Qinghai Plateau, the Western Qinling Orogen, the Qilian Orogen and the North China Craton) and two sand samples from the Luan River and the Yongding River (which run entirely within the North China Craton) were measured for U–Pb age and Lu–Hf isotopic compositions by excimer laser-ablation ICP-MS and MC-ICP-MS. Although regional variations exist, concordant detrital zircons from the Yellow River reveal three major age groups of 2.1–2.5Ga, 1.6–2.0Ga, and 150–500Ma. Detrital zircons from the smaller Luan and Yongding Rivers show three broadly similar major age groups at 2.3–2.6Ga, 1.6–2.0Ga, and 140–350Ma, but with narrower age ranges. Compared to the Luan and Yongding River zircons, the Yellow River zircons are characterized by a significant number of Neoproterozoic grains. Although Hf isotopic compositions show both juvenile crustal growth and crustal reworking for all age groups, much of the crustal growth of North China occurred in the Neoarchean and Mesoproterozoic. All three rivers are characterized by a common prominent group of Hf crust formation model ages at 2.4–2.9Ga with a peak at 2.7–2.8Ga. A less significant age group lies between 1.4 and 1.8Ga for the Yellow River, and between 1.6 and 1.9Ga for the Yongding River and Luan River. Crustal growth rates based on Hf continental crust formation model ages suggest 45% and 90% of the present crustal volume was formed by 2.5Ga and 1.0Ga, respectively, for the drainage area of the Yellow River. In comparison, 60% and 98% of the present crustal volume of the North China Craton was generated by 2.5Ga and 1.0Ga, respectively, for the Luan and Yongding Rivers. The 2.7–2.8Ga age peak observed in all river samples agrees well with the coeval major peak for global crustal growth. However, the other suggested global peaks of crustal growth at 3.4 and 3.8Ga are insignificant in North China. Taken together with our previous studies of the Yangtze Craton, which show insignificant crustal growth at 2.7–2.8Ga, we suggest that these advocated worldwide crust formation peaks be re-examined and treated carefully. Our results also show that Phanerozoic zircons may have been derived from crustal sources separated from the mantle up to 2.0Ga ago before the zircons crystallized, suggesting long-term preservation, reworking and recycling of the continental crust. [Copyright &y& Elsevier]

Abstract: The striation phenomenon in large-gap coplanar plasma display panel (PDP) has been investigated experimentally in macroscopic cells. The results show that the striations can generate either above anode accompanying the development of discharge or in the weak-field plasma channel near the dielectric surface after the discharge having developed. The surface state of the dielectric layer and the pre-accumulated wall charge play non-important role on the generation of striation. It is supposed that the physical process in the gas volume govern the formation of striation in PDP cells. [Copyright &y& Elsevier]

Abstract: The explanation for reduction in the peak heat release rate of polymer–clay nanocomposites which is normally accepted is that clay accumulates at the surface, forming a thermal shield which is also a barrier to mass transport. The process by which this clay arrives at the surface has never been described in print but the common assumption is that pyrolysis is required for clay accumulation to occur. In this work, X-ray photoelectron spectroscopy, a tool much more sensitive in surface analysis than conventional techniques, is used to probe the surface of polypropylene–clay nanocomposites that have been annealed at relatively low temperatures, well below that required for pyrolysis. The composition of the surface changes with time and temperature of annealing, which provide a strong indication that the clay at the surface undergoes chemical change at fairly low temperatures. [Copyright &y& Elsevier]

Abstract: The work focuses on a mechanistic study of the title system with the aid of both TGA–FTIR (in the gas phase) and XPS (in the condensed phase). It is concluded that: (1) although the change in yield of char for PC/PPFBS is insignificant with respect to PC itself it appears that the majority of the crucial FR activity is in the condensed phase as indicated by the XPS data; (2) TGA–FTIR experiments support the view that the degradation of polycarbonate proceeds by the cleavage of the Cα–O and the Cβ–H bonds, leading to the formation of dienes, diols and carbon dioxide; (3) the reverse reaction of the intermediates, like phenols, may occur via the basic catalyst, possibly K-alkyl oxide, a weaker base is generated in the process; (4) voluminous evolution of CO2 accelerated by PPFBS may give flame retardance by way of intumescent action and its dilution into the gas phase. [Copyright &y& Elsevier]

More information concerning the thermal degradation and charring of nanocomposites of poly(vinyl chloride), dioctyl phthalate and clay has been obtained by the use of X-ray photoelectron spectroscopy and the acquisition of the carbon (C1s), chlorine (Cl2p), and oxygen (O1s) spectra. In the cases of polystyrene–clay and poly(methyl methacrylate)–clay nanocomposites, it has been shown that the clay migrates to the surface as the temperature is raised and the polymer degrades, thereby confirming the barrier properties as a mechanism by which these materials function. For PVC–clay nanocomposites the surface at high temperatures is dominated by carbon, and not the oxygen of the clay. The presence of the clay does retard the chain-stripping degradation of the PVC and the enhanced char formation accounts for the observation of enrichment of carbon. [Copyright &y& Elsevier]

The electromagnetic(EM) wave absorption properties of carbon-based magnetic nanoparticles prepared by gaseous detonation and explosive detonation are different. In present study, the influence of detonation temperature on EM wave absorption property of Fe@C nanoparticles was studied by heat treatment. The results demonstrated that heat treatment was an easy and effective way to improve the EM wave absorption property of Fe@C nanoparticles. The reflection loss (RL) value reduced significantly from −1.8 dB to −17.1 dB, and the effective absorption frequency was 7.1 GHz. The improvement of phase and degree of graphitization resulted in the change of electromagnetic parameters, which led to a better impedance matching. As a result, the EM wave absorption property of Fe@C nanoparticles was enhanced. Detonation temperature is a key factor on EM wave absorption property of Fe@C nanoparticles, and heat treatment is an easy and useful way to enhance the EM wave absorbing ability of gaseous detonation Fe@C nanoparticles. Image 1 [ABSTRACT FROM AUTHOR]