Modification of the electrokinetic motion of microalgae through light illumination for viability assessment.

The viability detection of microalgae with the electrokinetic (EK) technique shows vast applications in the biology and maritime industry. However, due to the slight variations in the EK properties between alive and dead microalgae cells, the accuracy and practicability of this technique is limited. In this paper, the light illumination pretreatment was conducted to modify the EK velocity of microalgae for enhancing the EK difference. The effects of the illumination time and light color on the EK velocities of Chlorella vulgaris and Isochrysis galbana were systematically measured, and the EK differences between alive and dead cells were calculated and compared. The results indicate that under light illumination, the photosynthesis of the alive cells leads to the amplification of the zeta potential, leading toward increase in the EK difference along with the illumination time. By using light with different color spectra to treat the microalgae, it was found that the EK difference changes with the light color according to the following order: white light > red light > blue light > green light. The difference in EK potential with exposure to white light treatment surpasses over 10-fold in comparison to those without such treatment. The light pretreatment technique, as illustrated in this study, offers an advantageous strategy to enhance the EK difference between living and dead cells, proving beneficial in the field of microalgae biotechnology.

Photosynthetic characteristics of Tamarix chinensis under different groundwater depths in freshwater habitats.

Groundwater is the major source of water for Tamarix chinensis growth in the Yellow River Delta (YRD) region, and the groundwater depth (GWD) dramatically influences the physiological activities of T. chinensis. The quantitative response of the photosynthetic physiological process of T. chinensis to the GWD in freshwater habitats remains unclear. In this study, the response characteristics of gas exchange parameters in the leaves of three-year-old T. chinensis seedlings were measured and analyzed at a graded series of seven GWDs (0 m, 0.3 m, 0.6 m, 0.9 m, 1.2 m, 1.5 m and 1.8 m). The GWD thresholds corresponding to drastic changes in the photosynthetic efficiency and the GWDs of several levels of photosynthetic productivity and efficiency were also determined. In the freshwater habitats of the YRD, variations in GWD significantly altered the relative soil water content (RSWC) and thus influenced the photosynthetic efficiency of T. chinensis. RSWC at 0 ≤ GWD ≤ 0.9 m and GWD at 1.2 m ≤ GWD ≤ 1.8 m directly influenced the photosynthetic physiology of T. chinensis. When the GWD was 1.2 m, net photosynthetic rate (Pn), apparent quantum efficiency and water use efficiency (WUE) values all peaked. Thus, T. chinensis exhibited a high light and water use efficiency, wide ecological amplitude in terms of light, and high photosynthetic capacity. The optimum GWD for photosynthetic carbon assimilation and WUE in T. chinensis was determined to be 1.2 m. At a deep (≥1.64 m) or shallow (≤0.53 m) GWD, both Pn and WUE in T. chinensis clearly decreased below the corresponding mean values. The main causes for the reduction in Pn in these two GWD ranges (≤0.53 m, ≥1.64 m) were stomatal and nonstomatal limitations, respectively. Additionally, a moderate GWD of 1.09-1.25 m corresponded to the "high-productivity and high-efficiency GWD" range, in which T. chinensis displayed a high photosynthetic yield and WUE. Overall, the photosynthetic capacity of T. chinensis shows characteristics of high tolerance to moderate GWDs from 1.09 m to 1.25 m but intolerance at both shallow (≤0.53 m) and deep (≥1.64 m) GWDs in freshwater habitats.

Catalytic Asymmetric Hydrogenation of 3-Ethoxycarbonyl Quinolin-2-ones and Coumarins.

A protocol of iridium catalyzed asymmetric hydrogenation of 4-alkyl substituted 3-ethoxycarbonyl quinolin-2-ones and coumarins has been reported, providing a wide range of chiral dihydroquinolin-2-ones and dihydrocoumarins in high yields with excellent enantioselectivities (up to 99% ee) and high turnover numbers (up to 28 000). This efficient protocol was successfully applied for the synthesis of MPR3160 and the key chiral intermediate of R-106578.

Asymmetric Hydrogenation of ß-Aryl Alkylidene Malonate Esters: Installing an Ester Group Significantly Increases the Efficiency.

Herein, we report a practical method for efficient asymmetric hydrogenation of ß-aryl alkylidene malonates. With a site-specifically tailored chiral spiro iridium catalyst, a series of ß-aryl alkylidene malonate esters were hydrogenated to afford chiral malonate esters with good to excellent enantioselectivities (up to 99% ee) and high turnover numbers (up to 19000). The results showed that installing an ester group in α,ß-unsaturated carboxylic esters significantly increased the efficiency of their asymmetric hydrogenation reactions.

A dynamic kinetic asymmetric transfer hydrogenation-cyclization tandem reaction: an easy access to chiral 3,4-dihydro-2H-pyran-carbonitriles.

A chiral (mesitylene)RuCl(monosulfonated diamine) catalysed dynamic kinetic resolution (DKR)-asymmetric transfer hydrogenation (ATH) process is developed for highly enantio- (up to 99% ee) and diastereo- (up to 98 : 2 dr) selective reduction of challenging racemic α-aryl-γ-keto malononitriles. A spontaneous cyclization reaction of the hydrogenation products delivers a cascade process for efficient synthesis of useful enantioenriched 3,4-dihydro-2H-pyran-carbonitriles.

Dynamic Kinetic Resolution of Phthalides via Asymmetric Transfer Hydrogenation: A Strategy Constructs 1,3-Distereocentered 3-(2-Hydroxy-2-arylethyl)isobenzofuran-1(3H)-one.

Dynamic kinetic resolution of phthalides through asymmetric transfer hydrogenation for the construction of 3-(2-hydroxy-2-arylethyl)isobenzofuran-1(3H)-one with 1,3-distereocenters has been developed. This procedure is carried out under a mild condition at 40 °C catalyzed with RuCl[(S,S)-TsDPEN](mesitylene) using HCOOH/Et3N (5:2) as a hydrogen source. A variety of phthalides are smoothly transferred to provide optically pure phthalides with high yields, excellent enantioselectivities, and acceptable diastereomeric ratios.

Highly enantioselective one-pot synthesis of chiral ß-hydroxy sulfones via asymmetric transfer hydrogenation in an aqueous medium.

A mild transformation in an aqueous medium for the one-pot synthesis of optically active ß-hydroxy sulfones is described. The intermediates of ß-keto sulfones obtained via a nucleophilic substitution reaction of α-bromoketones and sodium sulfinates in H2O/MeOH (1:3, v/v) at 50 °C were reduced through Ru-catalyzed asymmetric transfer hydrogenation in one-pot using HCOONa as a hydrogen source providing a variety of chiral ß-hydroxy sulfones with high yields and excellent enantioselectivities.

Hollow-shell-structured nanospheres: a recoverable heterogeneous catalyst for rhodium-catalyzed tandem reduction/lactonization of ethyl 2-acylarylcarboxylates to chiral phthalides.

Chiral organorhodium-functionalized hollow-shell-structured nanospheres were prepared by immobilization of a chiral N-sulfonylated diamine-based organorhodium complex within an ethylene-bridged organosilicate shell. Structural analysis and characterization reveal its well-defined single-site rhodium active center, and transmission electron microscopy images reveal a uniform dispersion of hollow-shell-structured nanospheres. As a heterogenous catalyst, it exhibits excellent catalytic activity and enantioselectivity in synthesis of chiral phthalides by a tandem reduction/lactonization of ethyl 2-acylarylcarboxylates in aqueous medium. The high catalytic performance is attributed to the synergistic effect of the high hydrophobicity and the confined chiral organorhodium catalytic nature. The organorhodium-functionalized nanospheres could be conveniently recovered and reused at least 10 times without loss of catalytic activity. This feature makes it an attractive catalyst in environmentally friendly organic reactions. The results of this study offer a new approach to immobilize chiral organometal functionalities within the hollow-shell-structured nanospheres to prepare materials with high activity in heterogeneous asymmetric catalysis.