Bifunctional Oxo-Tethered Ruthenium Complex Catalyzed Asymmetric Transfer Hydrogenation of Aryl <i>N</i>‑Heteroaryl Ketones

A facile asymmetric transfer hydrogenation of <i>ortho</i>-substituted aryl <i>N</i>-heteroaryl ketones and non-<i>ortho</i>-substituted <i>N</i>-oxide of aryl <i>N</i>-heteroaryl ketones using a readily available oxo-tethered ruthenium complex as a catalyst and sodium formate as a hydrogen source in an aqueous solution has been discovered. A variety of chiral aryl <i>N</i>-heteroaryl methanols were obtained with up to 99.9% ee

Transformation of Alkynes into Chiral Alcohols via TfOH-Catalyzed Hydration and Ru-Catalyzed Tandem Asymmetric Hydrogenation

A novel full atom-economic process for the transformation of alkynes into chiral alcohols by TfOH-catalyzed hydration coupled with Ru-catalyzed tandem asymmetric hydrogenation in TFE under simple conditions has been developed. A range of chiral alcohols was obtained with broad functional group tolerance, good yields, and excellent stereoselectivities

SPORL Pretreatment Spent Liquors Enhance the Enzymatic Hydrolysis of Cellulose and Ethanol Production from Glucose

This study investigated the recycle utilization of SPORL pretreatment spent liquor. Three lignosulfonates (LSs) were purified from the spent liquor of SPORL pretreated Beetle-killed lodgepole pine (BKLP), Poplar NE222 (NE222), and Douglas-fir (FS10). The structural characterization showed that the apparent molecular mass and sulfur content of NE222-LS were lowest, but the phenolic group content was highest. FS10-LS, from a pH profiling SPORL pretreatment, had the highest apparent molecular mass but medium sulfur and phenolic group content. The spectral analyses exhibited that the guaiacyl unit was the main structure in BKLP and FS10 LSs, while NE222-LS mainly contained both guaiacyl and syringyl units. Both LSs and SPORL pretreatment spent liquors were used as additives to enzymatic hydrolysis of Whatman paper and ethanol production from glucose. LSs and liquors, from SPORL pretreated BKLP and NE222, could obviously enhance the enzymatic saccharification. Nevertheless, LS and liquor from SPORL pretreated FS10 presented a slight negative effect on enzymatic saccharification. All LSs and liquors with low concentration exhibited no inhibition on ethanol fermentation from glucose. When whole spent liquors without any detoxification were applied to prepare the fermentation medium with an initial glucose concentration of 100 g/L, the ethanol yield was almost the same as the control for BKLP and FS10 liquors. Nevertheless, the whole NE222 liquor without detoxification inhibited ethanol production thoroughly

Horseradish Peroxidase Modification of Sulfomethylated Wheat Straw Alkali Lignin To Improve Its Dispersion Performance

Wheat straw alkali lignin (WAL), byproducts from the alkali pulping process, is a low-value product with poor water solubility and limited dispersion performance. Sulfomethylated wheat straw alkali lignin (SWAL) was first prepared by sulfomethylation. In order to further improve the dispersion performance of WAL, a commercially available horseradish peroxidase (HRP) was then used to modify SWAL. Gel permeation chromatography showed an obvious increase in molecular weight after HRP modification by approximately 6 fold and 18 fold, compared with SWAL and WAL, respectively. The structural characterization was investigated by functional group content measurements and IR and ¹H NMR analyses. After the HRP modification, the phenolic and methoxyl group content decreased, while the sulfonic and carboxyl group content increased. Because of the higher molecular weight and hydrophilic group content, the HRP modification induced a significant improvement in adsorption and dispersion performance of WAL

Rational Design of Magnetic Micronanoelectrodes for Recognition and Ultrasensitive Quantification of Cysteine Enantiomers

Driven by the urgent need for recognition and quantification of trace amino acids enantiomers in various biologic samples, we demonstrate for the first time an ultrasensitive electrochemical chiral biosensor for cysteine (Cys) based on magnetic nanoparticles (Fe₃O₄@PDA/Cu_<i>x</i>O) as electrode units. d-Cys-Cu²⁺-d-Cys formed in the presence of cysteine exhibits strong stability and a shielding effect on the redox current of indicator Cu²⁺, which can be used to quantify and recognize d-Cys by square wave voltammetry. Simultaneous detection of d-Cys and homocysteine (Hcy) is achieved in the presence of other amino acids, demonstrating an excellent selectivity of the sensor. Moreover, aided by the enrichment treatment effect of magnetic micronanoelectrodes, an ultrahigh sensitivity up to 102 μA μM^–1 cm^–2 was achieved, the detection limit is reduced to picomolar level (83 pM) for d-Cys and can be used for the recognition of cysteine enantiomers. The proposed method has been verified by real sample analysis with satisfactory results. The results highlight the feasibility of our proposed strategy for magnetic micronanoelectrode sensor, electrochemical recognition, and quantification of d-Cys, which can be more broadly applicable than that with traditional electrode structures and further advance the field of electrochemical sensors

808 nm Excited Multicolor Upconversion Tuning through Energy Migration in Core–Shell–Shell Nanoarchitecture

NaGdF₄: A (A = Eu, Tb)@NaGdF₄: Yb, Tm@NaGdF₄: Yb, Nd core–shell–shell is designed to achieve 808 nm excited upconversion emission tuning. On the basis of the above core–shell–shell nanostructure, intense upconversion emission has been realized for activators without long-lived intermediate states (Eu³⁺, Tb³⁺) through Gd³⁺-mediated energy migration under 808 nm irradiation, enriching the emission colors. The spatial separation, where sensitizer (Nd³⁺), accumulator (Tm³⁺), and activator (Eu³⁺, Tb³⁺) are doped into separated layers, effectively suppresses nonradiative decays so that the doping concentration of Nd³⁺ can reach to 40%, vastly enhancing the luminescence intensity. Notably, when Gd³⁺ ions are replaced by Nd³⁺ or inert Y³⁺ in NaGdF₄: Yb, Nd outer shell, without Gd³⁺-mediated energy migration, the deleterious energy transfer from Tm³⁺ in the interlayer to surface quenchers is suppressed, and thus, more active energy is trapped by activators, which induces the further change of upconversion emission color. Furthermore, the multicolor upconversion tuning can also be realized via Tb³⁺-mediated energy migration. 808 nm excited multicolor upconversion tuning, overcoming low tissue penetration and overheating effect under 980 nm excitation, improves the feasibility of upconversion nanoparticles in multicolor imaging and multiplexed detection areas

Recycling Cellulase by a pH-Responsive Lignin-Based Carrier through Electrostatic Interaction

Enzymatic conversion of lignocelluloses into fermentable sugars is a key step in producing liquid fuels and chemicals in an ecofriendly and sustainable manner. However, because of the large quantities of cellulase required in enzymatic hydrolysis, the high cellulase cost make the production cost of glucose still high. To reduce the overall production cost and achieve the comprehensive utilization of lignocelluloses. A new intensive production process for enzymatic saccharification was developed: lignin, the residue of lignocellulosic substrates after enzymatic hydrolysis, was modified to a pH-responsive carrier (pH-LC) by simple graft reactions and used to recycle cellulase through electrostatic interaction. pH-LC exhibited reversible soluble–insoluble property as solution pH changed, and it did not inhibit cellulase activity. By simply adjusting the pH of the solution contained pH-LC and cellulase, cellulase could be precipitated or dissolved for recycling. pH-LC could recover more than 90% of filter paper activity in solution for cellulase CTec2. During the enzymatic hydrolysis of corncob residue, pH-LC could not only recover more than 50% of cellulase but also increase the yield of glucose from 78.1% to 93.0%. This new process is not only green and convenient but also well integrated with existing processes and easily applied

Media 1: Loop coupled resonator optical waveguides

Originally published in Optics Express on 06 October 2014 (oe-22-20-24202

Media 3: Loop coupled resonator optical waveguides

Originally published in Optics Express on 06 October 2014 (oe-22-20-24202

Media 4: Loop coupled resonator optical waveguides

Originally published in Optics Express on 06 October 2014 (oe-22-20-24202