Highly insulating alkane rings with destructive σ-interference

Science China Chemistry - Destructive quantum interference (DQI) provides a unique approach to controlling the leakage current in the OFF state of molecular devices. However, the DQI in...     

Role of compositional changes on thermal,magnetic,and mechanical properties of Fe-P-C-based amorphous alloys

This work aimed to tune the comprehensive properties of Fe-P-C-based amorphous system through investigating the role of microalloying process on the crystallization behavior,glass forming ability(GFA),soft magnetic features,and mechanical properties.Considering minor addition of elements into the system,it was found that the simultaneous microalloying of Ni and Co leads to the highest GFA,which was due to the optimization of compositional heterogeneity and creation of near-eutectic composition.Moreover,the FeCoNiCuPC amorphous alloy exhibited the best anelastic/viscoplastic behavior under the nanoindentation test,which was owing to the intensified structural fluctuations in the system.However,the improved plasticity by the extra Cu addition comes at the expense of magnetic properties,so that the saturation magnetization of this alloying system is significantly decreased compared to the FeCoPC amorphous alloy with the highest soft magnetic properties.In total,the results indicated that a combination of added elemental constitutes,i.e.,Fe69Co5Ni5Cu1P13C7 composition,provides an optimized state for the comprehensive properties in the alloying system.     

Enhancement of β-Glucan Biological Activity Using a Modified Acid-Base Extraction Method from Saccharomyces cerevisiae

Beta glucan (β-glucan) has promising bioactive properties. Consequently, the use of β-glucan as a food additive is favored with the dual-purpose potential of increasing the fiber content of food products and enhancing their health properties. Our aim was to evaluate the biological activity of β-glucan (antimicrobial, antitoxic, immunostimulatory, and anticancer) extracted from Saccharomyces cerevisiae using a modified acid-base extraction method. The results demonstrated that a modified acid-base extraction method gives a higher biological efficacy of β-glucan than in the water extraction method. Using 0.5 mg dry weight of acid-base extracted β-glucan (AB extracted) not only succeeded in removing 100% of aflatoxins, but also had a promising antimicrobial activity against multidrug-resistant bacteria, fungi, and yeast, with minimum inhibitory concentrations (MIC) of 0.39 and 0.19 mg/mL in the case of resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa, respectively. In addition, AB extract exhibited a positive immunomodulatory effect, mediated through the high induction of TNFα, IL-6, IFN-γ, and IL-2. Moreover, AB extract showed a greater anticancer effect against A549, MDA-MB-232, and HepG-2 cells compared to WI-38 cells, at high concentrations. By studying the cell death mechanism using flow-cytometry, AB extract was shown to induce apoptotic cell death at higher concentrations, as in the case of MDA-MB-231 and HePG-2 cells. In conclusion, the use of a modified AB for β-glucan from Saccharomyces cerevisiae exerted a promising antimicrobial, immunomodulatory efficacy, and anti-cancer potential. Future research should focus on evaluating β-glucan in various biological systems and elucidating the underlying mechanism of action.     

Short Synthesis of Functionalized Cyclic Homoallylsilanes

The synthesis of functionalized cyclic homoallylsilanes 5 and 6 was described starting from functional cycloalkenols 1 and 2, in which the addition of silylcuprate to the functional acetates 3 and 4 were used as the key reaction step.     

Dynamic Model of R&D,Spillovers, and Efficiency of Bertrand and Cournot Equilibria

Using an infinite-horizon two-player differential game, we derive and compare Bertrand and Cournot equilibria for a differentiated duopoly engaging in the process of R&D competition. The main findings of this study are as follows. First, Bertrand competition is more efficient if either R&D productivity is low or products are very different. Second, Cournot competition is more efficient provided that R&D productivity is high, products are close substitutes, and spillovers are not close to zero. This last result is different from what has been obtained in the literature. Hence, this shows that considering a dynamic model and more general investment costs does have an impact on the efficiency results.     

An Enhanced Process for the Production of a Highly Purified Extracellular Lipase in the Non-conventional Yeast <Emphasis Type="Italic">Yarrowia lipolytica</Emphasis>

Yarrowia lipolytica LgX64.81 is a non-genetically modified mutant that was previously identified as a promising microorganism for extracellular lipase production. In this work, the development of a fed-batch process for the production of this enzyme in this strain was described. A lipolytic activity of 2,145 U/mL was obtained after 32 h of batch culture in a defined medium supplemented with 10 g/L of tryptone, an enhancer of lipase expression. To maximize the volumetric productivity, two different fed-batch strategies had been investigated. In comparison to batch process, the intermittent fed-batch strategy had not improved the volumetric lipase productivity. In contrast, the stepwise feeding strategy combined with uncoupled cell growth and lipase production phases resulted in a 2-fold increase in the volumetric lipase productivity, namely, the lipase activity reached 10,000 U/mL after 80 h of culture. Furthermore, this lipase was purified to homogeneity by anion exchange chromatography on MonoQ resin followed by gel filtration on Sephacryl S-100. This process resulted in an overall yield of 72% and a 3.5-fold increase of the specific lipase activity. The developed process offers a great potential for an economic production of Lip2 at large scale in Y. lipolytica LgX64.81.     

Compound A Increases Cell Infiltration in Target Organs of Acute Graft-versus-Host Disease (aGVHD) in a Mouse Model

Systemic steroids are used to treat acute graft-versus-host disease (aGVHD) caused by allogenic bone marrow transplantation (allo-BMT); however, their prolonged use results in complications. Hence, new agents for treating aGVHD are required. Recently, a new compound A (CpdA), with anti-inflammatory activity and reduced side effects compared to steroids, has been identified. Here, we aimed to determine whether CpdA can improve the outcome of aGVHD when administered after transplantation in a mouse model (C57BL/6 in B6D2F1). After conditioning with 9Gy total body irradiation, mice were infused with bone marrow (BM) cells and splenocytes from either syngeneic (B6D2F1) or allogeneic (C57BL/6) donors. The animals were subsequently treated (3 days/week) with 7.5 mg/kg CpdA from day +15 to day +28; the controls received 0.9% NaCl. Thereafter, the incidence and severity of aGVHD in aGVHD target organs were analyzed. Survival and clinical scores did not differ significantly; however, CpdA-treated animals showed high cell infiltration in the target organs. In bulk mixed lymphocyte reactions, CpdA treatment reduced the cell proliferation and expression of inflammatory cytokines and chemokines compared to controls, whereas levels of TNF, IL-23, chemokines, and chemokine receptors increased. CpdA significantly reduced proliferation in vitro but increased T cell infiltration in target organs.     

Effect of Brownian motion on flow and heat transfer of nanofluids over a backward-facing step with and without adiabatic square cylinder

A mathematical model to predict large enhancement of thermal conductivity of nanofluids by considering the Brownian motion is proposed. The effect of the Brownian motion on the flow and heat transfer characteristics is examined. The computations were done for various types of nanoparticles such as CuO, Al₂O₃, and ZnO dispersed in a base fluid (water), volume fraction of nanoparticles ? in the range of 1 % to 6 % at a fixed Reynolds number Re = 450 and nanoparticle diameter d_np = 30 nm. Our results demonstrate that Brownian motion could be an important factor that enhances the thermal conductivity of nanofluids. Nanofluid of Al₂O₃ is observed to have the highest Nusselt number Nu among other nanofluids types, while nanofluid of ZnO nanoparticles has the lowest Nu. Effects of the square cylinder on heat transfer characteristics are significant with considering Brownian motion. Enhancement in the maximum value of Nu of 29 % and 26 % are obtained at the lower and the upper walls of the channel, respectively, by considering the Brownian effects, with square cylinder, compared with that in the case without considering the Brownian motion. On the other hand, results show a marked improvement in heat transfer compared to the base fluid, this improvement is more pronounced on the upper wall for higher ?.     

Crystal structure of bis 4-benzyl piperidinium bis dihydrogenmonophosphate trihydrogenmonophosphate

The salt bis 4-benzyl piperidinium bis dihydrogenmonophosphate trihydrogenmonophosphate (bis 4-BPP bis DPT) is monoclinic with the following unit cell dimensions: a = 13.132(2) Å, b = 8.755(2) Å, c = 13.643(2) Å, β = 92.40(2)°, space group P2₁ with Z = 2. The structure was solved by the Patterson method and refined to final R value of 0.0430. The structure consists of infinite parallel two-dimensional planes built of mutually H₂PO₄ ⁻, H₃PO₄ tetrahedra and cations connected by strong O–H···O and N–H···O hydrogen bonding. There are no contacts other than van der Waals interactions between the layers.