On a new FeOF polymorph: Synthesis and stability

A new polymorph of FeOF (up to now only known in its rutile type structure) was prepared by using a new synthesis approach formally based on anionic exchange using the well-known layered FeOCl as precursor. The synthesis was achieved using [CH₃C(CH₂O–)₂(COO–)B] to vehicle fluorine through the formation of soluble (CH₃)₄N⁺ [CH₃C(CH₂O–)₂(COO–)BF]⁻ and using N,N-dimethylformamide (DMF) as the reacting medium. The XRD pattern of layered FeOF can be indexed with an orthorhombic cell which doubles along the b axis (which is the direction perpendicular to the layers) with respect to that of pristine FeOCl (a = 3.792(1) Å, b = 12.699(1) Å, c = 3.321(1) Å). Both thermal analysis and diffraction indicate similar stability for the layered and rutile polymorphs. Such findings are rationalized through Density Functional Theory calculations. It is found that the energy difference between the more stable rutile and layered polymorphs is practically nul. The origin of the similar stability lies in the fact that although the number of Fe–F and Fe–O bonds is different in the two structures, the strength of both the total number of Fe–O as well as Fe–F bonds are found to be almost identical. Even if the crystal and electronic structures are considerably different, the total bonding and thus, the stability of the two polymorphs, is comparable. The stability of different FeOF rutile type structures is also analyzed.     

Capacitive deionization concept based on suspension electrodes without ion exchange membranes

A new type of capacitive deionization (CDI) system, based on capacitive suspension electrodes (CSEs), was developed for the purpose of desalting brackish and seawater through the use of flowable carbon suspensions. CSEs derived from activated carbon and acetylene black demonstrated a specific capacitance of 92 F g^− 1 in a static mode in a 0.6 M NaCl solution. The novel system introduced here is a proof of concept that capacitive suspension electrodes can be envisioned to desalt water without the aid of ion exchange membranes (IEMs).     

Influence of fineness on the cementitious properties of steel slag

In this paper, the influence of fineness on the cementitious properties of steel slag and the properties of cement containing steel slag with different finenesses were investigated. The results show that increasing the fineness can significantly enhance the early as well as the late cementitious properties of steel slag. However, the early hydrations of cement and steel slag tend to hinder each other especially in the case of large steel slag replacement and high fineness of steel slag. Therefore, increasing fineness of steel slag cannot improve the early cementitious properties of the cement containing steel slag. At 28 days, the hydrations of steel slag and cement tend to promote each other. Increasing the fineness of steel slag enhances the late cementitious properties of the cement containing steel slag significantly.     

A new high frequency dynamic mechanical analysis system: An approach to direct high frequency testing of tire tread rubber

Dynamic Mechanical Analysis (DMA) systems are measurement devices for obtaining master curves and complex modules of viscoelastic materials, such as rubbers. The conventional DMAs measurement systems in market have several limitations, which restrict their ability for operating at high frequencies. Thus, Williams, Landel and Ferry (WLF) relation is used to produce master curves and predict the material properties at high frequencies. In conventional DMAs, experiments are done in a range of temperatures, and then a master curve is made for a chosen reference temperature by shifting the measurements data to high frequencies. Therefore, the obtained results, which are not based on direct measurements, can be inaccurate. In order to overcome this problem a new simple shear high-frequency DMA (HFDMA) system is designed and built to directly measure the dynamic mechanical properties of viscoelastic material at high frequencies and the strain levels sufficient for tire manufacturers. The new HFDMA can be used to test any viscoelastic materials which have glass transmission temperature (Tg) lower than room temperature (about 23 °C) such as the Styrene-butadiene rubber (SBR). The SBR is the base material for tire tread. The designing process of this new HFDMA is presented in this paper. The rubber specimen shape is chosen by taking into account the shear elastic wave effect, bending, buckling effect and heat generation in the specimen. The repeatability test is accomplished to ensure that the results obtained from the new HFDMA are repeatable and the repeatability uncertainty is about 0.04%. The new HFDMA is validated by comparing to the direct test results of conventional DMA at 100 Hz. The direct high frequency (5 kHz) complex shear modulus and damping factor are compared with the master curve of the conventional DMA developed by the use of WLF relation for SBR. This comparison revealed that the complex shear modulus and damping factor of the SBR obtained from the HFDMA at 5 kHz and 0.05% strain amplitude are about 7% and 6.5% higher than those obtained from the conventional DMA, respectively.     

Deposition of In2O3 nanofibers on polyimide substrates to construct high-performance and flexible trimethylamine sensor

Flexible trimethylamine sensor has been realized based on In₂O₃ nanofibers via electrospinning and a deposition technique. The web-like In₂O₃ nanofibers with high length-to-diameter ratios are benefit for gas adsorption and desorption. High trimethylamine sensing properties are observed. The sensors can detect trimethylamine gas down to 1 ppm at 80 °C with the response up to 3.8. Additionally, rapid response (6 s) and recovery (10 s) behavior can also be obtained. Good reliability and flexibility are observed in 100 bending/extending cycles. Our results open a new route to construct flexible gas sensors in practice.     

Evaluation of pharmaceutical activities of G-protein coupled receptor targeted pharmaceuticals in Chinese wastewater effluent

The occurrence of biologically active pharmaceuticals in aquatic environments raised the potential risks to aquatic species. Among these marketed biological active pharmaceuticals, it has been estimated that 40% of them target G-protein-coupled receptors (GPCRs). We have illustrated pharmaceutical activities of GPCR targeted pharmaceuticals in English and Japanese wastewater by the in vitro transforming growth factor-α (TGFα) shedding assay. However, as the most important producer and consumer of pharmaceuticals, the occurrence of GPCR targeted pharmaceuticals in China had remained unclear. In this study, we investigated the pharmaceutical activities of GPCR targeted pharmaceuticals in secondary effluents of Chinese wastewater treatment plants. We discovered antagonistic activities against angiotensin (AT1) receptor at up to 7.2 × 102 ng-valsartan-equivalent quantity/L in Chinese wastewater for the first time as well as agonistic activities against dopamine (D2) receptor. Furthermore, in parallel with the assay, we determined concentrations of GPCR targeted pharmaceuticals in target wastewater by liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS). Through the comparison of predicted antagonistic activities calculated by concentrations and potency values from the assay, we found that the measured antagonistic activities against AT1 receptor from the assay were higher than the predicted AT1 activities from valsartan, irbesartan, and losartan, indicating the potential existence of other unknown AT1 antagonists in wastewater.     

Cheminformatics in MS-based environmental exposomics: Current achievements and future directions

Compound annotation using MS/MS data is the major bottleneck in interpretation of mass spectrometry data during non-targeted screening and suspect screening exposomics studies. Apart from compound identification using available databases or mass spectral libraries, the true challenge comes when completely new compounds have to be identified. Along with recent advances in MS instrumentation that set grounds to a new revolutionary age in environmental exposomics, a multitude of cheminformatics annotation approaches has been developed. Herein, we review the basic principles of the cutting-edge cheminformatics MS-based approaches employed in eco-exposome annotation.We give a solid background discussing the eco-exposome concept in relation to the advances in MS instrumentation, and define the three crucial cheminformatics tasks used in the eco-exposome annotation: molecular formula assignment, compound prioritization and compound annotation. The basic principles of compound annotation are discussed, which are based on three approaches of utilizing structural information inherent to MS data. These involve direct, indirect and joint annotation approaches. We assess their performance through the ability to annotate eco-exposome constituents. We discuss future perspectives and give directions to new annotation strategies and performance evaluation protocols aiming to solve current issues hampering the incorporation of cheminformatics annotation approaches in regular eco-exposome annotation workflows.     

The effect of polymer dispersions on the early hydration of calcium sulfoaluminate cement

The influence of three polymer dispersions [styrene–butadiene copolymer (SB), styrene–acrylic ester copolymer (SA) and polyacrylic ester (PA)] on the hydration of calcium sulfoaluminate (CSA) cement within 72 h was investigated by using isothermal conduction calorimetry, X-ray diffraction analysis and thermal gravimetric analysis. The results indicate that these three polymer dispersions perform different influences on the hydration heat flow of CSA cement during different periods, they all postpone the occurrence time of the maxima peaks, and its extent is mainly dependent on the addition amount. Polymer dispersions manifest great retardation on the initial hydration of CSA cement, and the effect is much more significant within 1 h. In this stage, the generation of ettringite is strongly delayed; however, the formation of ettringite is accelerated by these polymer dispersions at and after 2 h. Among these three polymer dispersions, PA demonstrates the highest acceleration effect on the hydration degree.

     

Dynamic adhesion due to fluid infusion

The resistance of fluid infusion inside a thin film that separates an opening gap leads to viscous adhesion. Viscous adhesion can be detrimental for some mechanical devices such as valves or during additive manufacturing processes. On the other hand, it is also a mechanism found in nature for dynamic reversible adhesion. In this article we review analysis and measurements of viscous adhesion. In particular, we give conditions where viscous adhesion dominates over other surface forces. We also describe how characteristics of the solid surfaces such as roughness and elasticity, as well as the compliance of the load cell can be incorporated in the analysis. Finally, we discuss the knowledge gaps and scientific areas where a better understanding of viscous adhesion could be beneficial.     

Experimental study on the smoke temperature evolution in a polyethylene (PE)-lined compartment on fire

Smoke temperature evolution in the upper layer of compartment fire, which is critical for the prediction of potential flashover, was experimentally investigated in a real building. Three-millimeter polyethylene (PE) slabs attached on the internal walls were employed as the lining material to address the effect of the melting and combustion of the lining material on the smoke temperature. A corner gasoline pool fire was utilized as the fire source. Two thermocouple trees, mounted vertically at the center and the open door, and a high-definition camera were utilized to record the smoke temperature history and experimental video. Meanwhile, some furniture was loaded to study its enhancement feature on fire intensity. Heat release rates (HRRs) at different stages were analyzed based on MQH method (McCaffrey, Quintiere and Harkleroad) and pool fire theory. Smoke temperature was estimated through an improved MQH correlation considering the melting of the PE slabs and an empirical model, BFD curve (Barnett in Fire Saf J 37: 437–463, 2002) combined. The results show that both the maximum HRR and smoke temperature, 925.91 kW and 491.7 °C, are lower than the critical values of flashover. The PE lining greatly intensifies the fire power and the resulting smoke temperature compared with the ones in noncombustible wall scenario. Combustion of the molten PE flowing down from the walls would lead to a secondary peak in smoke temperature curve, which is rarely considered in previous work.