Two-Dimensional Silicene–Stanene Heterostructures by Epitaxy

The synthesis of new Xenes and their potential applications prototypes have achieved significant milestones so far. However, to date the realization of Xene heterostructures in analogy with the well known van der Waals heterostructures remains an unresolved issue. Here, a Xene heterostructure concept based on the epitaxial combination of silicene and stanene on Ag(111) is introduced, and how one Xene layer enables another Xene layer of a different nature to grow on top is demonstrated. Single-phase (4 × 4) silicene is synthesized using stanene as a template, and stanene is grown on top of silicene on the other way around. In both heterostructures, in situ and ex situ probes confirm layer-by-layer growth without intercalations and intermixing. Modeling via density functional theory shows that the atomic layers in the heterostructures are strongly interacting, and hexagonal symmetry conservation in each individual layer is sequence selective. The results provide a substantial step toward currently missing Xene heterostructures and may inspire new paths for atomic-scale materials engineering.     

Electrospun fiber membranes from blends of poly(vinylidene fluoride) with fouling‐resistant zwitterionic copolymers

Nonwoven super‐hydrophobic fiber membranes have potential applications in oil–water separation and membrane distillation, but fouling negatively impacts both applications. Membranes were prepared from blends comprising poly(vinylidene fluoride) (PVDF) and random zwitterionic copolymers of poly(methyl methacrylate) (PMMA) with sulfobetaine methacrylate (SBMA) or with sulfobetaine‐2‐vinylpyridine (SB2VP). PVDF imparts mechanical strength to the membrane, while the copolymers enhance fouling resistance. Blend composition was varied by controlling the PVDF‐to‐copolymer ratio. Nonwoven fiber membranes were obtained by electrospinning solutions of PVDF and the copolymers in a mixed solvent of N,N‐dimethylacetamide and acetone. The PVDF crystal phases and crystallinities of the blends were studied using wide‐angle X‐ray diffraction and differential scanning calorimetry (DSC). PVDF crystallized preferentially into its polar β‐phase, though its degree of crystallinity was reduced with increased addition of the random copolymers. Thermogravimetry (TG) showed that the degradation temperatures varied systematically with blend composition. PVDF blends with either copolymer showed significant increase of fouling resistance. Membranes prepared from blends containing 10% P(MMA‐ran‐SB2VP) had the highest fouling resistance, with a fivefold decrease in protein adsorption on the surface, compared to homopolymer PVDF. They also exhibited higher pure water flux, and better oil removal in oil–water separation experiments. © 2018 Society of Chemical Industry     

Design,Synthesis, Radiosynthesis and Biological Evaluation of Fenretinide Analogues as Anticancer and Metabolic Syndrome-Preventive Agents

Fenretinide (4-HPR) is a synthetic derivative of all-trans-retinoic acid (ATRA) characterised by improved therapeutic properties and toxicological profile relative to ATRA. 4-HPR has been mostly investigated as an anti-cancer agent, but recent studies showed its promising therapeutic potential for preventing metabolic syndrome. Several biological targets are involved in 4-HPR's activity, leading to the potential use of this molecule for treating different pathologies. However, although 4-HPR displays quite well-understood multitarget promiscuity with regards to pharmacology, interpreting its precise physiological role remains challenging. In addition, despite promising results in vitro, the clinical efficacy of 4-HPR as a chemotherapeutic agent has not been satisfactory so far. Herein, we describe the preparation of a library of 4-HPR analogues, followed by the biological evaluation of their anti-cancer and anti-obesity/diabetic properties. The click-type analogue 3 b showed good capacity to reduce the amount of lipid accumulation in 3T3-L1 adipocytes during differentiation. Furthermore, it showed an IC₅₀ of 0.53±0.8 μM in cell viability tests on breast cancer cell line MCF-7, together with a good selectivity (SI=121) over noncancerous HEK293 cells. Thus, 3 b was selected as a potential PET tracer to study retinoids in vivo, and the radiosynthesis of [¹⁸F] 3b was successfully developed. Unfortunately, the stability of [¹⁸F] 3b turned out to be insufficient to pursue imaging studies.     

Media as Educator,Media as Disruptor: Conceptualizing the Role of Social Context in Media Effects

We document how social contexts serve to refract media effects. We theorized the relationship between media use and individual‐level knowledge (and attitude) would be stronger when community‐level knowledge (and attitude) was low than when it was high. Data come from a national survey (N = 12,608 women and 1,237 men) conducted in Nepal. Knowledge and stigma toward people living with HIV were the 2 dependent variables. Hypotheses were tested 12 times: across the use of 3 media (newspaper, radio, television) × 2 study outcomes (knowledge and attitudes) × 2 genders. Predicted interactions were supported in 9 of the 12 tests. Findings point to the need to take into account the role of community factors in theorizing about media effects.     

Crystal Structure and Improved Synthesis of 1‐(2H‐Tetrazol‐5‐yl)guanidium Nitrate

Energetic derivatives of tetrazoles are one of the key areas of research focus in pursuit of novel high energy materials, useful as propellants and explosives. Herein, the crystal structure and an improved synthetic procedure of 1‐(2H‐tetrazol‐5‐yl)guanidine ( 1 ) and its nitrate salt ( 2 ) are reported. The compounds were structurally characterized by spectroscopic (FT‐IR, ¹H NMR, ¹³C NMR) and elemental analysis. The molecular structure of tetrazolyl guanidium nitrate ( 2 ) was solved using low temperature single‐crystal X‐ray diffraction. 2 crystallized as its hemihydrate in the orthorhombic space group Fdd2, with a crystal density of 1.69 g cm⁻³. Thermal behavior and decomposition of the molecules were studied with differential scanning calorimetry (DSC). Molar enthalpy of formation (Δ_fH^m) of compound 2 was back calculated from heat of combustion (Δ_cH⁰) value obtained experimentally using bomb calorimetric measurements. Lattice enthalpy of 1‐(2H‐tetrazol‐5‐yl)guanidium nitrate was directly calculated from measured crystal density using Jenkins equation. Preliminary ballistic parameters of the compound were predicted and compared with reported high nitrogen tetrazole derivatives.     

Economics of herbaceous bioenergy crops for electricity generation: Implications for greenhouse gas mitigation

This paper examines the optimal land allocation for two perennial crops, switchgrass and miscanthus that can be co-fired with coal for electricity generation. Detailed spatial data at county level is used to determine the costs of producing and transporting biomass to power plants in Illinois over a 15-year period. A supply curve for bioenergy is generated at various levels of bioenergy subsidies and the implications of production for farm income and greenhouse gas (GHG) emissions are analyzed. GHG emissions are estimated using lifecycle analysis and include the soil carbon sequestered by perennial grasses and the carbon emissions displaced by these grasses due to both conversion of land from row crops and co-firing the grasses with coal. We find that the conversion of less than 2% of the cropland to bioenergy crops could produce 5.5% of the electricity generated by coal-fired power plants in Illinois and reduce carbon emissions by 11% over the 15-year period. However, the cost of energy from biomass in Illinois is more than twice as high as that of coal. Costly government subsidies for bioenergy or mandates in the form of Renewable Portfolio Standards would be needed to induce the production and use of bioenergy for electricity generation. Alternatively, a modest price for GHG emissions under a cap-and-trade policy could make bioenergy competitive with coal without imposing a fiscal burden on the government.     

Improved transfection efficiency of chitosan‐DNA complexes employing reverse transfection

The present study was designed to systematically compare the conventional and reverse transfection methodologies for chitosan/DNA complexes using a low molecular weight (MW) chitosan. The hydrodynamic diameter of the complexes, measured by Dynamic Light Scattering (DLS) was found to be ～ 216 nm and TEM investigations showed spherical and compact complexes with an average size of 200 nm. The transfection efficiency of chitosan using the two methodologies was assessed by employing reporter gene coding for green fluorescent protein (GFP) and luciferase. More than 50% of HEK 293 cells were transfected when transfection done using reverse transfection strategy at pH 6.5 with 10% serum for 24 h followed by media replenishment with pH 7.4 with 10% serum for an additional 24 h period. Also, the cytotoxicity of chitosan/DNA complexes was also considerably lower than the commercially available transfection reagent lipofectamine. Our investigation concludes that maximal transgene expression levels could be achieved using reverse transfection where the chitosan/DNA complexes are pre‐incubated on the plate surface followed by plating of cells at pH 6.5 with 10% serum for 24h and media resupplemented with pH 7.4 with 10% serum for an additional 24 h period. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Development of a continuous membrane nanobubble generation method applicable in liquid food processing

A novel continuous nanobubble generation method was developed using a commercial ceramic membrane as a nanobubble generator. CO₂ and air were infused externally across the ceramic membrane (pore size 50 nm) into the water flowing inside the ceramic membrane tube. Infusion of each gas was done in a single (20 s) and multiple passes (180 s) at 20–21°C. Results showed that gaseous nanobubbles could be generated even in a single pass. Low power ultrasound (200 kHz, 30W) was applied for the rapid assessment of nanobubble stability. Single-pass ultrasound treatment of the samples was carried out at two levels: 2.6 and 5.1 J mL⁻¹. Among the samples in which gases were infused for multiple passes, air nanobubbles were found more stable than CO₂. In contrast, an opposite trend was observed in those samples in which gases were infused in the single-pass only (20 s). This process has the potential to be applied to food processing industries, such as to enhance the products’ sensory attributes, the efficiency of membrane separation, food drying and liquid food transportation systems.     

Dealcoholization of Korean traditional rice wine,takju, combining thermal,bentonite clarification or reverse osmosis treatment

Food Science and Biotechnology - The objective of this study was to prepare low-alcoholic takju. Low-alcohol (3.06%) and dealcoholized (0.04–0.28%) takju samples were prepared by adopting...     

Requirements for product derivation support: Results from a systematic literature review and an expert survey

ContextAn increasing number of publications in product line engineering address product derivation, i.e., the process of building products from reusable assets. Despite its importance, there is still no consensus regarding the requirements for product derivation support.ObjectiveOur aim is to identify and validate requirements for tool-supported product derivation.MethodWe identify the requirements through a systematic literature review and validate them with an expert survey.ResultsWe discuss the resulting requirements and provide implementation examples from existing product derivation approaches.ConclusionsWe conclude that key requirements are emerging in the research literature and are also considered relevant by experts in the field.