Abstract: Defects on hollow silica spheres synthesized in a tetraethylorthosilicate-octylamine-HCl-H2O system were recorded by scanning microscope. Based on the results, influences of synthesis composition on the formation of these defects are discussed. It is evidenced that products prepared with different octylamine-to-tetraethylorthosilicate ratios may have surface depressions, cracks and non-hollow microspheres. However, by changing water and acid additions, these defects could be reduced or eliminated. Generally, samples synthesized with a large octylamine addition commonly exhibit surface depressions. A small octylamine or a large water addition benefits the formation of solid silica microspheres among the product. Acid, although is not indispensable for the formation of hollow spheres, helps to eliminate or reduce depressions on the hollow shells. It is explained that the added acid gives rise to a relative localized fast hydrolysis versus condensation, facilitating an easy mobility of hydrolyzed silica species, and consequently the shell surface is smoothened.

Abstract: We present a general description of the formalism of symmetry-adapted rotator functions (SARFs) for molecules in cylindrical confinement. Molecules are considered as clusters of interaction centers (ICs), can have any symmetry, and can display different types of ICs. Cylindrical confinement can be realized by encapsulation in a carbon nanotube (CNT). The potential energy of a molecule surrounded by a CNT can be calculated by evaluating a limited number of terms of an expansion into SARFs, which offers a significant reduction of the computation time. Optimal molecular orientations can be deduced from the resulting potential energy landscape. Examples, including the case of a molecule with cubic symmetry inside a CNT, are discussed.

Abstract: In this study, the healing of N-vacancy boron carbonitride nanosheet (NV-BC2NNS) and nanotube (NV-BC2NNT) by NO molecule is studied by means of density functional theory calculations. Two different N-vacancies are considered in each of these structures in which the vacancy site is surrounded by either three B-atoms (NB) or by two B- and one C-atom (NBC). By means of the healed BC2NNS and BC2NNT as a support, the removal of two toxic gas molecules (NO and CO) are applicable. It should be noted that the obtained energy barriers of both healing and oxidizing processes are significantly lower than those of graphene, carbon nanotubes or boron nitride nanostructures. Also, at the end of the oxidation process, the pure BC2NNS or BC2NNT is obtained without any additional defects. Therefore, by using this method, we can considerably purify the defective BC2NNS/BC2NNT. Moreover, according to the thermochemistry calculations we can further confirm that the healing process of the NV-BC2NNS and NV-BC2NNT by NO are feasible at room temperature. So, we can claim that this study could be very helpful in both purifying the defective BC2NNS/BC2NNT while in the same effort removing toxic NO and CO gases.

Abstract: The electrical asymmetry effect is realized by applying multiple frequency power sources
(13.56 MHz and 27.12 MHz) to a capacitively biased substrate electrode in a specific inductively
coupled plasma reactor. On the one hand, by adjusting the phase angle θ between the multiple
frequency power sources, an almost linear self-bias develops on the substrate electrode, and
consequently the ion energy can be well modulated, while the ion flux stays constant within a
large range of θ. On the other hand, the plasma density and ion flux can be significantly
modulated by tuning the inductive power supply, while only inducing a small change in the self-
bias. Independent control of self-bias/ion energy and ion flux can thus be realized in this specific
inductively coupled plasma reactor.

Abstract: In this paper we employ first-principles calculations to investigate the effect of substitutional Si doping in the amorphous calcium-phosphate (a-HAP) structure on the work of adhesion, integral charge transfer, charge density difference and theoretical tensile strengths between an a-HAP coating and amorphous titanium dioxide (a-TiO2) substrate systemically. Our calculations demonstrate that substitution of a P atom by a Si atom in a-HAP (a-Si-HAP) with the creation of OH-vacancies as charge compensation results in a significant increase of the bonding strength of the coating to the substrate. The work of adhesion of the optimized Si-doped interfaces reaches a value of up to -2.52 J m(-2), which is significantly higher than for the stoichiometric a-HAP/a-TiO2. Charge density difference analysis indicates that the dominant interactions at the interface have significant covalent character, and in particular two Ti-O and three Ca-O bonds are formed for a-Si-HAP/a-TiO2 and one Ti-O and three Ca-O bonds for a-HAP/a-TiO2. From the stress-strain curve, the Young's modulus of a-Si-HAP/a-TiO2 is calculated to be about 25% higher than that of the a-HAP/a-TiO2, and the yielding stress is about 2 times greater than that of the undoped model. Our calculations therefore demonstrate that the presence of Si in the a-HAP structure strongly alters not only the bioactivity and resorption rates, but also the mechanical properties of the a-HAP/a-TiO2 interface. The results presented here provide an important theoretical insight into the nature of the chemical bonding at the a-HAP/a-TiO2 interface, and are particularly significant for the practical medical applications of HAP-based biomaterials.

Abstract: The world famous Alhambra monument in Granada, Southern Spain, listed as UNESCO world cultural heritage since 1984, represents probably the most beautiful example of Islamic art and architecture from the Middle Ages in Europe. It is visited by ca. 2 million people annually. Granada is situated in a natural basin, surrounded by mountains with altitudes up to 3500 m. Due to this topography and the prevailing low wind speeds, pollution-derived and especially traffic-derived particulate matter often accumulates in the urban air. In order to evaluate the potential conservation risks from the surrounding air, the atmospheric composition in the Alhambra monument was evaluated. Indoor temperature and relative humidity fluctuations were evaluated for their potential degenerative effects. Furthermore, the atmospheric composition in the Alhambra was analyzed in terms of inorganic gases (NO2, SO2, O3, and NH3) and black carbon. It was found that the open architecture protected the indoor environments from developing a potentially harmful microclimate, such as the build-up of humidity resulting from the huge number of daily tourists. On the downside, the strong ventilation made the indoor air hardly different from outdoor air, as characterized by strong diurnal temperature and relative humidity gradients and high traffic-derived pollutant levels.

Abstract: Demand response (DR) can aid with grid integration of renewables, ensuring security of supply, and reducing generation costs. However, not enough is known about how residential customers’ perceptions of DR shape their response to such programs. This paper offers a deeper understanding of – and reveals the heterogeneity in – this relationship by conducting a quantile regression analysis of a Belgian DR trial, combining data on response with information on household attitudes towards smart appliances. Results overall suggest that improving response requires subtle shifts in electricity consumption behaviour, which can be achieved through changes in user perceptions. Specifically, if customers are inclined to be flexible, a stronger perception of smart appliances as being beneficial can greatly improve response. With those who are less flexible, the cost of smart appliances is a bigger concern. Thus, when designing DR programs, policymakers should aim to promote modest behaviour changes – so as to minimise inconvenience – in customers, by improving awareness on the benefits of smart appliances. Uptake of such DR programs may be improved by explaining the financial benefits or offering incentives to less flexible population segments. Lastly, improving response among older population segments will require a deeper investigation into their concerns.

Abstract: Radioactive particles originating from nuclear fuel reprocessing at the United Kingdom Atomic Energy Authority's Dounreay Facility were inadvertently released to the environment in the late 1950s to 1970s and have subsequently been found on site grounds and local beaches. Previous assessments of risk associated with encountering a particle have been based on conservative assumptions related to particle composition and speciation. To reduce uncertainties associated with environmental impact assessments from Dounreay particles, further characterization is relevant. Results of particles available for this study showed variation between Dounreay Fast Reactor (DFR) and Materials Test Reactor (MTR) particles, reflecting differences in fuel design, release scenarios, and subsequent environmental influence. Analyses of DFR particles showed they are small (100-300 mu m) and contain spatially correlated U and Nb. Molybdenum, part of the DFR fuel, was identified at atomic concentrations below 1%. Based on SR-based micrometer-scale X-ray Absorption Near Edge Structure spectroscopy (mu-XANES), U may be present as U (IV), and, based on a measured Nb/U atom ratio of similar to 2, stoichiometric considerations are commensurable with the presence of UNb2O7. The MTR particles were larger (740-2000 mu m) and contained U and Al inhomogeneously distributed. Neodymium (Nd) was identified in atomic concentrations of around 1-2%, suggesting it was part of the fuel design. The presence of U(IV) in MTR particles, as indicated by mu-XANES analysis, may be related to oxidation of particle surfaces, as could be expected due to corrosion of UAlx fuel particles in air. High U-235/U-238 atom ratios in individual DFR (3.2 +/- 0.8) and MTR (2.6 +/- 0.4) particles reflected the presence of highly enriched uranium. The DFR particles featured lower Cs-137 activity levels (2.00-9.58 kBq/particle) than the MTR (43.2-641 kBq Cs-137/particle) particles. The activities of the dose contributing radionuclides Sr-90/Y-90 were proportional to Cs-137 (Sr-90/Cs-137 activity ratio approximate to 0.8) and particle activities were roughly proportional to the size. Based on direct beta measurements, gamma spectrometry, and the VARSKIN6 model, contact dose rates were calculated to be approximately 74 mGy/h for the highest activity MTR particle, in agreement with previously published estimates. (C) 2020 The Authors. Published by Elsevier B.V.

Abstract: Marine recirculating aquaculture system (MRAS) is an effective technology that provides sustainable farming of food fish globally. However, dissolved organics material (chemical oxygen demand, COD) and especially ammonia are produced from uneaten feed and metabolic wastes of fish. To purify the MRAS water, this study adopted a sequencing biofilm batch reactor (SBBR) and comparatively investigated the performances of four different carriers on ammonia and COD removal. Results indicated that the NH4+-N removal rates were 0.045 +/- 0.05, 0.065 +/- 0.008, 0.089 +/- 0.005, and 0.093 +/- 0.003 kg/(m(3)center dot d), and the COD removal rates were 0.019 +/- 0.010, 0.213 +/- 0.010, 0.255 +/- 0.015, and 0.322 +/- 0.010 kg/(m(3)center dot d) in the SBBRs packed with porous plastic, bamboo ring, maifan stone, and ceramsite carriers, respectively. Among the four carriers, ceramsite exhibited the best performance for both NH4+-N (80%) and COD (33%) removal after the SBBR reached the steady-state operation conditions. For all carriers studied, the NH4+-N removal kinetics could be well simulated by the first-order model, and the NH4+-N and COD removal rates were logarithmically correlated with the carrier's specific surface area. Due to its high ammonia removal, stable performance and easy operation, the ceramsite-packed SBBR is feasible for MRAS water treatment.

Abstract: Latest synthesis of ZnSb monolayer, encouraged us to conduct density functional theory (DFT) simulations in order to study the structural, magnetic, electronic/optical and mechanical features of the sp2-hybridized honeycomb ZnSb monolayer (ML-ZnSb) and bilayer (BL-ZnSb). Our structural optimizations reveal that ML-ZnSb is an anisotropic hexagonal structure while BL-ZnSb is composed of shifted ZnSb layers which are covalently binded. ML-ZnSb is found to be a ferromagnetic metal, in contrast BL-ZnSb has a non-magnetic indirect band gap semiconducting ground state. For the in-plane polarization, first absorption peak of ML-ZnSb and BL-ZnSb confirm the absorbance of the light within the infrared domain wand visible range, respectively. Moreover, our results reveal that the layer-layer chemical bonding in BL-ZnSb significantly enhances the mechanical response of ML-ZnSb whose in-plane stiness is the smallest among all 2D materials (2DM). Notably, the strong in-plane anisotropy of ML-ZnSb in its stiness reduces in BL-ZnSb.

Abstract: We demonstrate a simple and robust method for inducing and detecting changes of magnetic flux quantization in the absence of an externally applied magnetic field. In our device, an isolated ring is interconnected with two access loops via permalloy cores, forming a superconducting transformer. By applying and tuning a direct current at the first access loop, the number of flux quanta trapped in the isolated ring is modified without the aid of an external field. The flux state of the isolated ring is simply detected by recording the evolution of the critical current of the second access loop.

Abstract: In this work we present for the first time, to our knowledge, the CVD epitaxial growth of beta -SiC using an ion beam synthesized (IBS) beta -SiC layer as seed, which has been formed by multiple implantation into Si wafers at 500 degreesC. The ion beam synthesized continuous layer is constituted by beta -SiC nanocrystals that are well oriented relative to the silicon substrate. Comparison of the epitaxial growth on these samples with that on silicon test samples, both on and off-axis, is performed. The results show that the epitaxial growth can be achieved on the IBS samples without the need of the carbonization step and that the structural quality of the CVD layer is comparable to that obtained on a carbonized silicon sample. Improvement of the quality of the deposited layer is proposed.

Abstract: In the present contribution several advanced electron microscopy techniques are employed in order to describe chemical and structural features of the nano- and microstructure of a Ni45.5Ti45.5Nb9 alloy. A line-up of Nb-rich nano-precipitates is found in the Ni-Ti-rich austenite of as-cast material. Concentration changes of the matrix after annealing are correlated with changes in the transformation temperatures. The formation of rows and plates of larger Nb-rich precipitates and particles is described. The interaction of a twinned martensite plate with a Nb-rich nano-precipitate is discussed and the substitution of Nb atoms on the Ti-sublattice in the matrix is confirmed.