Stability improvement of the Nieuwland catalyst in the dimerization of acetylene to monovinylacetylene

In the process of dimerization of acetylene to produce monovinylacetylene （MVA）,the loss of active component CuCl in the Nieuwland catalyst due to the formation of a dark red precipitate was investigated.The formula of the precipitate was CuCl·2C2H2·1/5NH 3,and it was presumed to be formed by the combination of NH 3,C2H2 and [Cu]-acetylene π-complex,which was an intermediate in the dimerization reaction.The addition of hydrochloric acid into the catalyst can reduce the formation of precipitate,whereas excessive H＋ is unfavorable to the dimerization reaction of acetylene.To balance between high acetylene conversion and low loss rate of CuCl,the optimum mass percentage of HCl in the added hydrochloric acid was determined.The result showed the optimum mass percentage of HCl decreased from 5.0% to 3.2% when the space velocity of acetylene was from 140 h-1 to 360 h-1.The result in this work also indicated the pH of the Nieuwland catalyst should be kept in the range of 5.80-5.97 during the reaction process,which was good for both catalyst life and acetylene conversion.

Effect of solvent on catalytic performance of anhydrous catalyst in acetylene dimerization to monovinylacetylene

The production of monovinylacetylene （MVA） through Cu（I）-catalyzed acetylene dimerization reaction was performed in different reaction media. Based on the analyses of crystals precipitated from the catalyst solution and UV-Vis spectra of the catalysts, the reaction mechanism and solvent dependence were studied. The highest yield of MVA can be obtained when dimethylformamide is used as solvent because of its strong coordination ability to Cu（I）. The activation of C=C bond is presumed to be improved when the catalytic metal ion is coordinated by a solvent with less steric hindrance and electron-rich coordination atom. The results of the present study provide a possible way to accelerate the metal-catalyzed homogeneous reaction of alkyne substrates through careful selection of a solvent.

Applications,of fluorescence lifetime imaging in clinical medicine

Fluorescence lifetime is not only associated with the molecular structure f fuorophores,but alsostrongly depends on the environment around them,which llows fuorescence lifetime imagingmicroscopy(FLIM)to be used as a tool for precise measurement of the cell or tisue microenvironment,This review introduces the basic principle of fuorescence lifetime imagingtechnology and its application in clinical medicine,including research and diagnosis of diseases inskin,brain,eyes,mouth,bone,blood vessels and cavity organs,and drug evaluation.As anoninvasive,nontoxic and nonionizing radiation technique,FLIM demonstrates excellent per-formance with high sensitivity and specificity,which allows to determine precise position of thelesion and,thus,has good potential for application in biomedical research and clinical diagnosis.

Engineering an enthesis-like graft for rotator cuff repair:An approach to fabricate highly biomimetic scaffold capable of zone-specifically releasing stem cell differentiation inducers

Rotator cuff(RC)attaches to humerus across a triphasic yet continuous tissue zones(bone-fibrocartilage-tendon),termed“enthesis”.Regrettably,rapid and functional enthesis regeneration is challenging after RC tear.The existing grafts bioengineered for RC repair are insufficient,as they were engineered by a scaffold that did not mimic normal enthesis in morphology,composition,and tensile property,meanwhile cannot simultaneously stimulate the formation of bone-fibrocartilage-tendon tissues.Herein,an optimized decellularization approach based on a vacuum aspiration device(VAD)was developed to fabricate a book-shaped decellularized enthesis matrix(O-BDEM).Then,three recombinant growth factors(CBP-GFs)capable of binding collagen were synthesized by fusing a collagen-binding peptide(CBP)into the N-terminal of BMP-2,TGF-β3,or GDF-7,and zone-specifically tethered to the collagen of O-BDEM to fabricate a novel scaffold(CBP-GFs/O-BDEM)satisfying the above-mentioned requirements.After ensuring the low immunogenicity of CBP-GFs/O-BDEM by a novel single-cell mass cytometry in a mouse model,we interleaved urine-derived stem cell-sheets into this CBP-GFs/O-BDEM to bioengineer an enthesis-like graft.Its high-performance on regenerating enthesis was determined in a canine model.These findings indicate this CBP-GFs/O-BDEM may be an excellent scaffold for constructing enthesis-like graft to patch large/massive RC tears,and provide breakthroughs in fabricating graded interfacial tissue.

A high-efficiency regenerative shock absorber considering twin ball screws transmissions for application in range-extended electric vehicles

Renewable energy technologies,particularly in electric vehicles(EVs),have received significant attention in re-cent years.The wasted energy in a vehicle’s shock absorber can be converted into an alternative energy source by regenerative shock absorbers.In this paper,a high-efficiency regenerative shock absorber considering twin ball screws transmissions is proposed for application in range-extended electric vehicles.The proposed regenerative shock absorber can convert vibrational kinetic energy,which is traditionally dissipated as heat in suspension systems,into electricity.The proposed system is divided into four modules:suspension vibration input module,transmission module,generator module and power storage module.Induced by road roughness,the irregular linear oscillations of the suspension are transmitted to the suspension vibration input module.The reciprocating vibrations are converted into unidirectional rotation of the generator by a pair of ball screws,gears,and two overrun clutches in the transmission module.The utilisation of different screw pitches leads to different damping coefficients for upward and downward progress,enabling the shock absorber to fully utilise elastic elements to im-prove vehicle comfort when compressed and quickly absorb vibrations when stretched.The electricity produced by the generator is stored in supercapacitors to charge the battery and extend the range of EVs.The mechanical properties of the full-scaled fabricated prototype were studied by utilising a mechanical testing and sensing fix-ture.An average power output of 3.701 W in 1Hz-3 mm sinusoidal vibration input and a peak efficiency of 51.1%and average efficiency of 36.4%were achieved in a bench tests.The range can be approximately extended by 1 mile per 100 miles when EV is driving on the road of class B with a speed of 60 km/h,demonstrating that the proposed high-efficiency regenerative shock absorber is beneficial for harvesting renewable energy,and practical and significant for extending the range of EVs.