Protein Residue Contact Prediction Based on Deep Learning and Massive Statistical Features from Multi-Sequence Alignment

Sequence-based protein tertiary structure prediction is of fundamental importance because the function of a protein ultimately depends on its 3 D structure.An accurate residue-residue contact map is one of the essential elements for current ab initio prediction protocols of 3 D structure prediction.Recently,with the combination of deep learning and direct coupling techniques,the performance of residue contact prediction has achieved significant progress.However,a considerable number of current D...     

Epoxidation reaction of perfluoroalkenes with tert-amine N-oxide

Straight-chain aliphatic terr-amine N-oxides were found to be useful oxidizing agent for epoxidation of tri- and tetra-substituted perfluoroalkenes under mild conditions in high yields.The process for epoxidation by employing tri-n-butylamine N-oxide gave the best result in the reagent survey.     

First total synthesis of isoquinolinone alkaloid marinamide and its methyl ester

The first total synthesis of isoquinolinone alkaloid marinamide 1 and its methyl ester 2 was described. The key steps involved a regioselective Frieclel-Crafts reaction of 1-benzyl-1H-pyrrole to form the intermediate 8.     

Photolyses of mammalian carboxy-hemoglobin studied by photoacoustic calorimetry

The enthalpy and conformational volume changes in the photolyses of carboxy-hemoglobin (HbCO) of human, bovine, pig, horse and rabbit are investigated by photoacoustic calorimetry. Considering the time scales of the exciting laser pulse and the receiving ultrasound transducers (PVDF films and PZT ceramics), as well as the reaction lifetimes in the photolysis processes of HbCO, the measured results are related to the geminate recombination and tertiary relaxation in photolyses of HbCO. Moreover, the quantum yields of the five mammals are also measured by laser pump-probe technique. The results show that the dynamic parameters, such as enthalpy and conformational volume changes, differ between the processes of the geminate recombination and tertiary relaxation. Also, the dynamic parameters differ among the five mammals although some of them may be consistent with each other.     

Teeming stream protection using an argon shroud during casting of steel ingots

Two kinds of argon shroud protection devices with two different basic structures were designed and investigated. Industrial experiments and numerical simulations were used to examine the protection effect, and the mechanism of air entrapment during the casting of steel ingots was analyzed. The influence of the structure of the argon shroud protection device on the protection effect was investigated. An argon shroud protection device mounted to the nozzle holder on the bottom of the ladle does not provide a good protection effect because air can easily flow into the teeming system and cause reoxidation of molten steel during teeming. By contrast, an argon shroud protection device seated on the top of the central trumpet provides an excellent protection effect, where air has little chance of flowing into the teeming system during casting. The feasibilities of the argon shroud protection devices are discussed.     

Enantiomeric separations of four basic drugs containing N-alkyl groups by a RP-HPLC system using SBE-β-CD as chiral mobile phase additive

The chiral separations of four pharmaceutical racemates which contain N-alkyl groups were satisfactorily resolved using SBE-β-CD as a chiral mobile phase additive(CMPA)in a RP-HPLC system(the resolution is 2.701 for ondansetron hydrochloride,1.996 for sulpiride,1.293 for clenbuterol hydrochloride and 0.816 for omeprazole).In addition,the effects of different parameters such as CD type and CD concentration were investigated.The separation mechanism arises through the combination of several potential interactions,including electrostatic interactions as well as hydrogen bonding interactions and hydrophobic inclusion interactions,which allow for the SBE-β-CD–drug complexation with strong stereoselectivity and stability.The resolution also relates to the number and location of N atoms in the enantiomers.This method will be applicable to the isolation of various types of biologically important enantiomers containing N-alkyl groups.     

Photofragment translational spectroscopy at 304 nm from C-H symmetric stretch excited CH3I [v 1 = 1]

The 304 nm photodissociation of the C-H symmetric stretch excited CH3I[v1=1,v2=0](v1 denotes the C-H symmetric stretch mode,and v2 denotes the umbrella mode)is studied with our simple photofragment translational spectrometer.An IR laser is used to excite the ground state CH3I[0,0]to the C-H symmetric stretch excited CH3I[1,0].With IR laser OFF and ON,the fractions of photofragments CH3(ν1,ν2)from the 304 nm photodissociation of CH3I[1,0]have been determined through the photofragment translational spectra(PTS)from measuring I and I*and also through the PTS from measuring CH3(0,0)(1,0)(0,1)and(1,1).The experimental results show that the C-H symmetric stretch vibration(v1=1)in parent molecules is about 66%retained in the photofragments in the I channel,but only 24%in the I*channel.The populations of photofragments CH3(0,2)and(0,3)are higher than CH3(0,0)and(0,1),showing strong inverted population both in I and I*channels.     

Spatiotemporally-regulated multienzymatic polymerization endows hydrogel continuous gradient and spontaneous actuation

There are several natural materials which have evolved functional gradients,ingeniously attaining maximal efficacy from limited components.Herein,we utilized the spatiotemporal distribution of initiator acetylacetone to regulate the multienzyme polymerization and fabricate a chitosan-polymer hydrogel.The temporal priority order of acetylacetone was higher than phenolmodified chitosan by density functional theory calculation.The acetylacetone within the gelatin could gradually diffuse spatially into the chitosan hydrogel to fabricate the composite hydrogel with gradient network structure.The gradient hydrogel possessed a transferring topography from the two-dimensional pattern.A continuously decreased modulus along with acetylacetone diffusion was confirmed by atomic force microscope-based force mapping experiment.The water-retaining ability of various regions was confirmed by low-field nuclear magnetic resonance(NMR)and thermogravimetric analysis(TG)analysis,which led to the spontaneous actuation of gradient hydrogel with maximum 1821°/h curling speed and 227°curling angle.Consequently,the promising gradient hydrogels could be applied as intelligent actuators and flexible robots.     

Large-area periodic lead halide perovskite nanostructures for lenticular printing laser displays

Lenticular printing technique provides a promising way to realize stereoscopic displays,especially,when microscopic optical structures are integrated into light-emitting materials/devices.Here,we fabricated large-area periodic structures with a spatial resolution at a wavelength scale from hybrid perovskite materials via a space-confined solution growth method.It takes advantages of both high refractive index contrast and high luminescence brightness,which allows the optical modulation on not only the reflection of illumination,but also the light emission from hybrid perovskites.The distributed feedback within these periodic structures significantly improves the degree of polarization and directionality of laser actions while their threshold is also reduced.These findings enable us to present a prototype of lenticular printing laser displays that vary emission colors at different view angles,which may find applications in creating high-resolution and high-contrast holographical images.     

High-power and high-temperature THz quantum-cascade lasers based on lens-coupled metal-metal waveguides

A metal-metal waveguide quantum cascade laser with an abutted silicon hyperhemispherical lens is demonstrated at ~4.1 THz. The device produced 145 mW of peak pulsed power at 5 K with a wall-plug power efficiency of 0.7%, lasing up to a maximum operating temperature of 160 K. The far-field beam pattern has a full width at half-maximum value of ~4.8 degrees in the H plane. The same device produced ~26 mW of peak power using a Winston cone instead of a lens, lasing up to 165 K. The large increase in output power is mainly attributed to an increase in collection efficiency.