Structure Identification of Two-Dimensional Colloidal Semiconductor Nanocrystals with Atomic Flat Basal Planes

Discrete nature of thickness and flat basal planes of two-dimensional (2D) nanostructures display unique diffraction features. Their origin was uncovered by a new analysis method of powder X-ray diffraction, which reveals thickness and lattice orientation of the 2D nanostructures. Results indicate necessity of adoption of a different unit cell from the corresponding bulk crystal with the same internal atomic packing. For CdSe 2D nanostructures with zinc blende atomic packing, pseudotetragonal lattices are adequate, instead of face-centered cubic

Robust and Flexible Free-Standing Films for Unidirectional Drug Delivery

Robust and flexible free-standing polymer films for unidirectional drug delivery are fabricated by sandwiching drug-containing polyelectrolyte multilayer films between poly­(lactic-<i>co</i>-glycolic acid) (PLGA) barrier and capping layers. The drug-containing films are fabricated by layer-by-layer (LbL) assembly of chemically cross-linked poly­(allylamine hydrochloride)–dextran (PAH-D) microgel and hyaluronic acid (HA), which can load negatively charged cancer-inhibiting drug, methotrexate (MTX). Because the PLGA barrier layer effectively blocks MTX release, MTX can be predominantly released from the PLGA capping layer of the free-standing film. This increases the efficacy of released MTX to cancer cells while minimizing its side effects on the normal tissues. We believe that the unidirectional drug delivery free-standing films can open a new avenue to design of highly efficient drug delivery systems for biomedical application

Robust and Flexible Free-Standing Films for Unidirectional Drug Delivery

Robust and flexible free-standing polymer films for unidirectional drug delivery are fabricated by sandwiching drug-containing polyelectrolyte multilayer films between poly­(lactic-<i>co</i>-glycolic acid) (PLGA) barrier and capping layers. The drug-containing films are fabricated by layer-by-layer (LbL) assembly of chemically cross-linked poly­(allylamine hydrochloride)–dextran (PAH-D) microgel and hyaluronic acid (HA), which can load negatively charged cancer-inhibiting drug, methotrexate (MTX). Because the PLGA barrier layer effectively blocks MTX release, MTX can be predominantly released from the PLGA capping layer of the free-standing film. This increases the efficacy of released MTX to cancer cells while minimizing its side effects on the normal tissues. We believe that the unidirectional drug delivery free-standing films can open a new avenue to design of highly efficient drug delivery systems for biomedical application

EC₅₀ values of the compounds with higher initial activity against four strains of fungi.

<p>EC₅₀ values of the compounds with higher initial activity against four strains of fungi.</p

Bioactivity and structure-activity relationship of cinnamic acid esters and their derivatives as potential antifungal agents for plant protection

<div><p>A series of cinnamic acid esters and their derivatives were synthesized and evaluated for antifungal activities in vitro against four plant pathogenic fungi by using the mycelium growth rate method. Structure−activity relationship was derived also. Almost all of the compounds showed some inhibition activity on each of the fungi at 0.5 mM. Eight compounds showed the higher average activity with average EC₅₀ values of 17.4–28.6 μg/mL for the fungi than kresoxim-methyl, a commercial fungicide standard, and ten compounds were much more active than commercial fungicide standards carbendazim against <i>P</i>. <i>grisea</i> or kresoxim-methyl against both <i>P</i>. <i>grisea</i> and <i>Valsa mali</i>. Compounds <b>C1</b> and <b>C2</b> showed the higher activity with average EC₅₀ values of 17.4 and 18.5 μg/mL and great potential for development of new plant antifungal agents. The structure−activity relationship analysis showed that both the substitution pattern of the phenyl ring and the alkyl group in the alcohol moiety significantly influences the activity. There exists complexly comprehensive effect between the substituents on the phenyl ring and the alkyl group in the alcohol moiety on the activity. Thus, cinnamic acid esters showed great potential the development of new antifungal agents for plant protection due to high activity, natural compounds or natural compound framework, simple structure, easy preparation, low-cost and environmentally friendly.</p></div

Rapid Access to Spirocylic Oxindoles: Application of Asymmetric N‑Heterocyclic Carbene-Catalyzed [3 + 3] Cycloaddition of Imines to Oxindole-Derived Enals

A chiral N-heterocyclic carbene (NHC)-catalyzed [3 + 3] cycloaddition reaction of imines and oxindole-derived enals was developed for rapid access to spirocylic oxindoles. In most cases, the desired spirocylic oxindole products were obtained in high yields and excellent enantioselectivities with less than 1 h of reaction time

Diurnal and Seasonal Variations in the Net Ecosystem CO₂ Exchange of a Pasture in the Three-River Source Region of the Qinghai−Tibetan Plateau

<div><p>Carbon dioxide (CO₂) exchange between the atmosphere and grassland ecosystems is very important for the global carbon balance. To assess the CO₂ flux and its relationship to environmental factors, the eddy covariance method was used to evaluate the diurnal cycle and seasonal pattern of the net ecosystem CO₂ exchange (NEE) of a cultivated pasture in the Three-River Source Region (TRSR) on the Qinghai−Tibetan Plateau from January 1 to December 31, 2008. The diurnal variations in the NEE and ecosystem respiration (R_e) during the growing season exhibited single-peak patterns, the maximum and minimum CO₂ uptake observed during the noon hours and night; and the maximum and minimum R_e took place in the afternoon and early morning, respectively. The minimum hourly NEE rate and the maximum hourly R_e rate were −7.89 and 5.03 μmol CO₂ m⁻² s⁻¹, respectively. The NEE and R_e showed clear seasonal variations, with lower values in winter and higher values in the peak growth period. The highest daily values for C uptake and R_e were observed on August 12 (−2.91 g C m⁻² d⁻¹) and July 28 (5.04 g C m⁻² day⁻¹), respectively. The annual total NEE and R_e were −140.01 and 403.57 g C m⁻² year⁻¹, respectively. The apparent quantum yield (α) was −0.0275 μmol μmol⁻¹ for the entire growing period, and the α values for the pasture’s light response curve varied with the leaf area index (LAI), air temperature (T_a), soil water content (SWC) and vapor pressure deficit (VPD). Piecewise regression results indicated that the optimum T_a and VPD for the daytime NEE were 14.1°C and 0.65 kPa, respectively. The daytime NEE decreased with increasing SWC, and the temperature sensitivity of respiration (Q₁₀) was 3.0 during the growing season, which was controlled by the SWC conditions. Path analysis suggested that the soil temperature at a depth of 5 cm (T_soil) was the most important environmental factor affecting daily variations in NEE during the growing season, and the photosynthetic photon flux density (PPFD) was the major limiting factor for this cultivated pasture.</p></div

Robust, Flexible, and Bioadhesive Free-Standing Films for the Co-Delivery of Antibiotics and Growth Factors

Free-standing polymer films that adhere strongly to tissue and can codeliver multiple therapeutic agents in a controlled manner are useful as medical plasters. In this study, a bilayer polymer film comprising a drug reservoir layer and a supporting layer is fabricated by spin-coating poly­(lactic-<i>co</i>-glycolic acid) (PLGA) on top of a layer-by-layer assembled film of poly­(β-amino esters) (PAE), alginate sodium (ALG), and recombinant human basic fibroblast growth factor (bFGF). Apart from bFGF, the bilayer film can also load antibiotic drug ceftriaxone sodium (CTX) by a postdiffusion process. The PLGA supporting layer facilitates the direct peeling of the bilayer film from substrate to produce a robust and flexible free-standing film with excellent adhesion onto the human skin and porcine liver. The excellent adhesion of the bilayer film originates from the ALG component in the drug reservoir layer. CTX is quickly released by easily breaking its electrostatic interaction with the drug reservoir layer, whereas the sustained release of bFGF is due to the slow degradation of PAE component in the drug reservoir layer. Wounds can be synergetically treated by fast release of CTX to effectively eradicate invasive bacteria and by sustained release of bFGF to accelerate wound healing. Our results serve as a basis for designing multifunctional free-standing films with combination therapy for biomedical applications

Bio-oil production from hydrogenation liquefaction of rice straw over metal (Ni, Co, Cu)-modified CeO₂ catalysts

<p>This paper describes catalytic hydrogenation liquefaction of rice straw over metal (Ni, Co, and Cu)-modified CeO₂ catalysts for bio-oil production. The results show that the highest rice straw conversion (89.08%) and bio-oil yield (66.7%) were obtained over Ni/CeO₂ catalyst. The bio-oil contains mainly phenols, high-value-added, and widely used chemicals. Furthermore, metal-modified CeO₂ catalysts can significantly influence the components of bio-oil with the highest percentage of C7-C10 compounds. This work thus demonstrates that metal/CeO₂ catalysts can be effective in improving the bio-oil yield and selectivity in hydro-liquefaction of rice straw into bio-oil.</p

hiPS cell-derived neurons exhibit functional neuronal characteristics.

<p>(A–J) hiPS cells differentiate to mature neurons that express the neuronal markers NeuN (A), Neurofilament L (B), Tuj1 (E), Synapsin1 (F), and MAP2 (I) 4 weeks after terminal differentiation on Matrigel. (C) and (G) are merged images from (A–B) and (E–F), respectively. (D) is a magnified image of hiPS cell-derived neurons. (H) and (J) are magnifications of (G) and (I), respectively. Green is NF-L and synapsin; blue is DAPI; and red is NeuN, Tuj1 and MAP2. Bar = 30 µm for A to C, 10 µm for D–J. Images were chosen from areas dense with cells showing neuronal morphology. (K) Representative action potentials measured from hiPS cell-derived neurons 4 weeks after terminal differentiation. Most cells showed a single action potential spike while some exhibited a train of action potentials. The recorded action potentials are in response to 30 µA current injections under current clamp mode. n = 10 neurons. (L) Top panel shows rapid inward and slow outward currents elicited by step from −40 to 60 mV from a holding potential of −70 mV in hiPS cell-derived neurons 4 weeks after terminal differentiation. The rapid inward sodium current disappears with the addition of 0.5 µM TTX, a sodium channel blocker (lower panel). n = 10 neurons.</p