MXene@c-MWCNT Adhesive Silica Nanofiber Membranes Enhancing Electromagnetic Interference Shielding and Thermal Insulation Performance in Extreme Environments

A lightweight flexible thermally stable composite is fabricated by com-bining silica nanofiber membranes(SNM)with MXene@c-MWCNT hybrid film.The flexible SNM with outstanding thermal insulation are prepared from tetraethyl orthosilicate hydrolysis and condensation by electrospinning and high-temperature calcination;the MXene@c-MWCNT_(x:y)films are prepared by vacuum filtration tech-nology.In particular,the SNM and MXene@c-MWCNT_(6:4)as one unit layer(SMC_(1))are bonded together with 5 wt%polyvinyl alcohol(PVA)solution,which exhibits low thermal conductivity(0.066 W m^(-1)K^(-1))and good electromagnetic interference(EMI)shielding performance(average EMI SE_(T),37.8 dB).With the increase in func-tional unit layer,the overall thermal insulation performance of the whole composite film(SMC_(x))remains stable,and EMI shielding performance is greatly improved,especially for SMC_(3)with three unit layers,the average EMI SET is as high as 55.4 dB.In addition,the organic combination of rigid SNM and tough MXene@c-MWCNT_(6:4)makes SMC_(x)exhibit good mechanical tensile strength.Importantly,SMC_(x)exhibit stable EMI shielding and excellent thermal insulation even in extreme heat and cold environment.Therefore,this work provides a novel design idea and important reference value for EMI shielding and thermal insulation components used in extreme environmental protection equipment in the future.

Sequestration and Carbon Storage Potential of Tropical Forest Reserve and Tree Species Located within Benue State of Nigeria

Carbon sequestration potential of tree species within forest reserves and other sites in Makurdi Benue state of Nigeria was investigated using non-destructive Walkley-Black technique. The result indicates that P. americana has the highest CO2 sequestration potential (125,916.7 kg), while T. grandis (10.4 kg) and D. regia (26.1 kg) were the least. The study also shows that trees (T. grandis, S. actinophylla and P. americana) with thick vegetation, broad and clustered leaves were found to be better CO2 sequesters. The relationship between the tree height and amount of CO2 sequestered gave a regression equation of y = 67898x + 9509 with R2 = 0.266, indicating insignificant variations existing between tree height and CO2 sequestration at P > 0.05. Variations however existed between tree dominance and CO2 sequestration among trees investigated. This finding strategically positions Benue tropical forest in line for carbon credit financing while substantiating the importance of preserving our indigenous forest and tree species.

Morphology-controlled transformation of Cu@Au core-shell nanowires into thermally stable Cu3Au intermetallic nanowires

Multimetallic nanowires with long-range atomic ordering hold the promise of unique physicochemical properties in many applications.Here we demonstrate the synthesis and study the stability of CU3AU intermetallic nanowires.The synthesis is achieved by using Cu@Au core-shell nanowires as precursors.With appropriate Cu/Au stoichiometry,the Cu@Au core-shell nanowires are transformed into fully ordered Cu3Au nanowires under thermal annealing.Thermally-driven atom diffusion accounts for this transformation as revealed by X-ray diffraction and electron microscopy studies.The twin boundaries abundant in the Cu@Au core-shell nanowires facilitate the ordering process.The resulting CU3AU intermetallic nanowires have uniform and accurate atomic positioning in the crystal lattice,which enhances the nobility of Cu.No obvious copper oxides are observed in fully ordered Cu3Au nanowires after annealing in air at 200℃,a temperature that is much higher than those observed in Cu@Au core-shell and pure Cu nanowires.This work opens up an opportunity for further research into the development and applications of intermetallic nanowires.

A library of carbon-supported ultrasmall bimetallic nanoparticles

Small-sized bimetallic nanoparticles that possess numerous accessible metal sites and optimal geometric/electronic structures show great promise for advanced synergetic catalysis but remain synthetic challenge so far.Here,an universial synthetic method is developed for building a library of bimetallic nanoparticles on mesoporous sulfur-doped carbon supports,consisting of 24 combinations of 3 noble metals(that is,Pt,Rh,Ir)and 7 other metals,with average particle sizes ranging from 0.7 to 1.4 nm.The synthetic strategy is based on the strong metal-support interaction arising from the metal-sulfur bonding,which suppresses the metal aggregation during the H2-reduction at 700℃ and ensure the formation of small-sized and alloyed bimetallic nanoparticles.The enhanced catalytic properties of the ultrasmall bimetallic nanoparticles are demonstrated in the dehydrogenation of propane at high temperature and oxidative dehydrogenations of N-heterocycles.

Co-encapsulation efficiency of silk sericin-alginate-prebiotics and the effectiveness of silk sericin coating layer on the survival of probiotic Lactobacillus casei

The use of silk sericin protein as a biomaterial to co-encapsulate probiotic Lactobacillus casei TISTR 1463 with alginate and various prebiotics was determined.In addition,0.2%silk sericin was also evaluated as a coating material to improve the viability of probiotic cells.Silk sericin coating has the potential to enhance probiotic survival in freeze-dried microcapsules.Under refrigerated storage condition of 4℃for 120 days,alginate-silk sericin-maltitol with silk sericin coating(ASM-C)provided the best performance with the lowest inactivation rate(k)and the highestδparameter(the first decimal reduction time)applied by the log-linear and Weibull models,respectively.However,the stability was relatively low at the temperature of 30℃.Co-encapsulation of alginate-silk sericin-prebiotic and coated with silk sericin exerted a protective impact on the strain survival when exposed to high temperatures and transited through the digestive system.

Broadband tunable liquid crystal terahertz waveplates driven with porous graphene electrodes

Versatile devices,especially tunable ones,for terahertz imaging,sensing and high-speed communication,are in high demand.Liquid crystal based components are perfect candidates in the optical range;however,they encounter significant challenges in the terahertz band,particularly the lack of highly transparent electrodes and the drawbacks induced by a thick cell.Here,a strategy to overcome all these challenges is proposed:Few-layer porous graphene is employed as an electrode with a transmittance of more than 98%.A subwavelength metal wire grid is utilized as an integrated high-efficiency electrode and polarizer.The homogeneous alignment of a high-birefringence liquid crystal is implemented on both frail electrodes via a non-contact photo-alignment technique.A tunable terahertz waveplate is thus obtained.Its polarization evolution is directly demonstrated.Furthermore,quarter-wave plates that are electrically controllable over the entire testing range are achieved by stacking two cells.The proposed solution may pave a simple and bright road toward the development of various liquid crystal terahertz apparatuses.