Preparation and Properties of Polyaniline in the Presence of Trehalose

Oxidative polymerization of aniline in aqueous solution in the presence of trehalose was conducted. Fourier transform infrared spectroscopy confirmed successful preparation of polyaniline containing a trace amount of trehalose. Electron spin resonance spectroscopy revealed that electron spin concentration of the polyaniline increases with aniline/trehalose ratio in the polymerization. Scanning electron microscopy revealed that the polyaniline shows granular and porous morphology. Electrical conductivity of these polyanilines was in the order of 10-4 S/cm.

Tunneling Electrons Triggered Energy Transfer between Coherently Coupled Donor-Acceptor Molecules

Energy transfer is ubiquitous in natural and artificial lightharvesting systems,and coherent energy transfer,a highly efficient energy transfer process,has been accepted to play a vital role in such systems.However,the energy oscillation of coherent energy transfer is exceedingly difficult to capture because of its evanescence due to the interaction with a thermal environment.Here a microscopic quantum model is used to study the time evolution of electrons triggered energy transfer between coherently coupled donoracceptor molecules in scanning tunneling microscope(STM).A series of topics in the plasmonic nanocavity(PNC)coupled donor-acceptor molecules system are discussed,including resonant and nonresonant coherent energy transfer,dephasing assisted energy transfer,PNC coupling strength dependent energy transfer,Fano resonance of coherently coupled donor-acceptor molecules,and polariton-mediated energy transfer.

Position Verification of the RADPOS 4-D <i>In-Vivo</i>Dosimetry System

The accuracy of the position measurements obtained by the radiation positioning system (RADPOS) was evaluated under static and dynamic conditions. In the static verifications, the RADPOS was fixed to the treatment couch in a photon treatment room and a proton treatment room, and was translocated with the treatment couch in x, y and z directions. Because the presence of magnetic and/or electrically conductive materials can cause a systematic shift in the measured position by distorting the RADPOS transmitted field, the effect of metals on the performance of the positioning system was also investigated. Dynamic verification was performed using the couch drive and a dynamic anthropomorphic thorax phantom. We thus confirmed the utility of RADPOS as a position sensor to perform in vivo dosimetry.

In Vivo Dosimetry of an Anthropomorphic Phantom Using the RADPOS for Proton Beam Therapy

The radiation positioning system (RADPOS) combines an electromagnetic positioning sensor with metal oxide semiconductor field-effect transistor (MOSFET) dosimetry, enabling simultaneous online measurement of dose and spatial position. Evaluation points can be determined with the RADPOS. The accuracy of in-vivo proton dosimetry was evaluated using the RADPOS and an anthropomorphic head and neck phantom. MOSFET doses measured at 3D positions obtained with the RADPOS were compared with treatment plan values calculated using a simplified Monte Carlo (SMC) method. MOSFET responses, which depend strongly on the linear energy transfer of the proton beam, were corrected using the SMC method. The SMC method was used to calculate only dose deposition determined by the experimental depth-dose distribution and lateral displacement of protons due to the multiple scattering effect in materials and incident angle. This method thus enabled rapid calculation of accurate doses in even heterogeneities. In vivo dosimetry using the RADPOS, as well as MOSFET doses, agreed with SMC calculations in the range of ?3.0% to 8.3%. Most measurement errors occurred because of uncertainties in dose calculations due to the 1-mm position error. The results indicate that uncertainties in measurement position can be controlled successfully within 1 mm when using the RADPOS with in-vivo proton dosimetry.

Review of current ZT>1 thermoelectric sulfides

Thermoelectrics has played a fascinating role in the developments of direct energy conversion technologies.Over the past decade,sulfur-based thermoelectric materials have been significantly advanced in optimizing electrical and thermal transport due to their similarities in chemical and structural properties with tellurides and selenides.This review provides research progress on metal sulfides,particularly focuses on materials exhibiting high thermoelectric figure of merit(ZT>1.0).It highlights the potential compounds,e.g.Cu-S,Sn-S,Pb-S based,and polysulfides.Great strategies of superionic conducting,band configuration tuning,high-entropy alloying,and anomalous harmonic scattering are try to demonstrate the performance-improved mechanisms for thermoelectric sulfides.In addition,some common synthesis recipes are briefly introduced,and thereby making potential candidates as excellent alternatives for producing thermoelectric power generators in the mid temperature.Key outcomes along with how to further improve the thermoelectric performance and promote its scale-up applications are also outlined at the end.

Ligand density-dependent influence of arginine-glycine- aspartate functionalized gold nanoparticles on osteogenic and adipogenic differentiation of mesenchymal stem cells

Extracellular matrix （ECM） plays a very important role in regulating cell function and fate. It is highly desirable to fabricate biomimetic models to investigate the role of ECM in stem cell differentiation. In this study, arginine- glycine--aspartate （RGD）-modified gold nanoparticles （Au NPs） with tunable surface ligand density were prepared to mimic the ECM microenvironment. Their effect on osteogenic and adipogenic differentiation of human mesenchymal stem cells （MSCs） was investigated. The biomimetic Au NPs were taken up by MSCs in a ligand density-dependent manner. The biomimetic NPs with a high RGD density had an inhibitive effect on the alkaline phosphatase （ALP） activity, calcium deposition, and osteogenic marker gene expression of MSCs. Their effect on oil droplet formation and adipogenic marker gene expression was negative when RGD density was low, while their effect was promotive when RGD density was high. The biomimetic Au NPs regulated the osteogenic and adipogenic differentiation of MSCs mainly through affecting the focal adhesion and cytoskeleton. This study highlights the roles of biomimetic NPs on stem cell differentiation that could provide a meaningful strategy in fabricating functional biomaterials for tissue engineering and biomedical applications.

Microstructure analysis and thermoelectric properties of iron doped CuGaTe_(2)

Chalcopyrite related compounds have attracted much attention in recent years due to their promising thermoelectric properties.In this research we report Fe doping in chalcopyrite-type CuGaTe_(2)and its influence on structural and thermal transport properties.We synthesized polycrystalline samples with composition CuGa_(1-x)Fe_(x)Te_(2)with x=0.0 to 0.05 by spark plasma sintering method.For structural analysis powder X-ray diffraction and electron probe micro analysis were employed.Solubility of Fe in CuGaTe_(2)was found to be very small,and other phases like FeTe_(2)and CuTe were identified.Thermal conductivity showed a significant decrease with the addition of Fe up to x=0.02,which started to increase for x≥0.03.On the other hand,the addition of Fe caused slight increase in the power factor from 1.3mW/K^(2)m for x=0.0 to 1.6 mW/K^(2)m for x=0.02 at T=770 K.As a result,ZT peak value of 0.92 is recorded for x=0.02 at 870 K,which corresponds to an enhancement of 60%from that of non-doped CuGaTe_(2).This work demonstrates that thermoelectric properties of compositematerials can be greatly improved by controlling its microstructure.

A HfC nanowire point electron source with oxycarbide surface of lower work function for high-brightness and stable field-emission

Electric field-induced point electron source is highly demanded for microscopy,spectroscopy,lithography,X-ray tubes,microwave devices,and data displays.However,the instability in emission current and requirement of ultrahigh vacuum have often limited its extensive applications.Herewith we report a single-crystalline HfC nanowire with oxycarbide emission surface for stable electron emission at 50 nA with fluctuations less than 1%in a vacuum of 4×10^−7 Pa.The emitter has a low work function of 2.5 eV measured by the field emission Fowler-Nordheim curve and it is in good agreement with density functional theory(DFT)calculations.The energy spread is in a range of 0.21–0.26 eV with a corresponding reduced brightness 1.95×10^11−3.81×10^11 A·m^−2·sr^−1·V^−1.The HfC nanowire with oxycarbide emission surface is a qualified candidate for the next-generation electron source with high brightness,large current,and low energy spread.

Using orbital sensitivity analysis to pinpoint the role of orbital interactions in thermoelectric power factor

The modification of the electronic band structure is of critical importance for thermoelectric materials whose heat to electricity power generation is related to carrier effective mass and alignment of semiconductor band edges.One approach to optimize the electronic band structure is by modification of orbital interactions through doping or alloying.While the current ab-initio quantum chemical calculations can help us to investigate orbital components of electronic bands,they reveal little information on the relative tunability of electronic states and transport properties with respect to orbital interactions.In this work,we present a method,based on a symmetry-adapted tight-binding model and sensitivity analysis,that can pinpoint the role of orbital interactions in determining electronic band structure and transport properties.As an application,a systematic theoretical analysis is used to show how the power factor of PbTe can/cannot be improved by playing with interatomic orbital interactions.The orbital interaction sensitivity analysis introduced in this work can easily be applied to other compounds or properties.

Machine learning of organic solvents reveals an extraordinary axis in Hansen space as indicator of spherical precipitation of polymers

Machine learning is an emerging tool in the field of materials chemistry for uncovering a principle from large datasets.Here,we focus on the spherical precipitation behavior of polymers and computationally extract a hidden trend that is orthogonal to the availability bias in the chemical space.For constructing a dataset,four polymers were precipitated from 416 solvent/nonsolvent combinations,and the morphology of the resulting precipitates were collected.The dataset was subjected to computational investigations consisting of principal component analysis and machine learning based on random forest model and support vector machine.Thereby,we eliminated the effect of the availability bias and found a linear combination of Hansen parameters to be the most suitable variable for predicting precipitation behavior.The predicted appropriate solvents are those with low hydrogen bonding capability,low polarity,and small molecular volume.Furthermore,we found that the capability for spherical precipitation is orthogonal to the availability bias and forms an extraordinary axis in Hansen space,which is the origin of the conventional difficulty in identifying the trend.The extraordinary axis points toward a void region,indicating the potential value of synthesizing novel solvents located therein.

Purcell effect of GaAs quantum dots by photonic crystal microcavities

We fabricate photonic crystal slab microcavities embedded with GaAs quantum dots by electron beam lithography and droplet epitaxy. The Purcell effect of exciton emission of the quantum dots is confirmed by the micro photoluminescence measurement. The resonance wavelengths, widths, and polarization are consistent with numerical simulation results.

An antiferromagnetic {Mn_8} ring supported by planar multidentate ligands

Complexation of the planar multidentate ligand 3,5-bis-（2-hydroxyphenyl）pyrazole （H3L） with manganese chloride leads to the formation of the polynuclear complex [MnIHsL4Oa（MeO）a（MeOH）8] （1）. 1 has an octanuclear macrocyclic core in which the MnnI ions are bridged by four L molecules to form a ring type structure. Antiferromagnetic interactions were shown to be op- erative between metal centers.

Influence of viscosity on chondrogenic differentiation of mesenchymal stem cells during 3D culture in viscous gelatin solution-embedded hydrogels

Differentiation of human bone marrow-derived mesenchymal stem cells(hMSCs)is regulated by a variety of cues of their surrounding microenvironments.In particular,mechanical properties of cell culture matrices have been recently disclosed to play a pivotal role in stem cell differentiation.However,it remains elusive how viscosity affects the chondrogenic differentiation of hMSCs during three-dimensional(3 D)culture.In this study,a 3 D culture system that was established by embedding viscous gelatin solution in chemically cross-linked gelatin hydrogels was used for 3 D culture of hMSCs in gelatin solutions with different viscosities.The influence of solution viscosity on chondrogenic differentiation of hMSCs was investigated.Viscous gelatin solutions promoted cell proliferation in the order of low,middle and high viscosity while elastic hydrogels restricted cell proliferation.High viscosity gelatin solution led to increased production of the cartilaginous matrix.Under the synergistic stimulation of chondrogenic induction factors,high viscosity was beneficial for the chondrogenic differentiation of hMSCs.The results suggested the role of viscosity should be considered as one of the dominant mechanical cues affecting stem cell differentiation.

Baryon-Baryon interactions from lattice QCD

We report on new attempt to investigate baryon-baryon interactions in lattice QCD.From the Bethe-Salpeter （BS） wave function,we have successfully extracted the nucleon-nucleon （NN） potentials in quenched QCD simulations,which reproduce qualitative features of modern NN potentials.The method has been extended to obtain the tensor potential as well as the central potential and also applied to the hyperonnucleon （YN） interactions,in both quenched and full QCD.

Nanophotonic-structured front contact for high-performance perovskite solar cells

We report the design of a nanophotonic metaloxide front contact aimed at perovskite solar cells(PSCs)to enhance optoelectronic properties and device stability in the presence of ultraviolet(UV)light.High-quality Cr-doped ZnO film was prepared by industrially feasible magnetron sputter deposition for the electron transport layer of PSCs.As a means,the influence of the Cr content on the film and device was systematically determined.In-depth device optics and electrical effects were studied using advanced three-dimensional opto-electrical multiphysics rigorous simulations,optimizing the front contact for realizing high performance.The numerical simulation was validated by fabricating PSCs optimized to reach high performance,energy conversion efficiency(ECE)=17.3%,open-circuit voltage(V_(OC))=1.08 V,short-circuit current density(J_(SC))=21.1 mA cm^(-2),and fillfactor(FF)=76%.Finally,a realistic front contact of nanophotonic architecture was proposed while improving broadband light absorption of the solar spectrum and light harvesting,resulting in enhanced quantum efficiency(QE).The nanophotonic PSC enables J_(SC)improvement by~17%while reducing the reflection by 12%,resulting in an estimated conversion efficiency over 23%.It is further demonstrated how the PSCs’UV-stability can be improved without considerably sacrificing optoelectronic performances.Particulars of nanophotonic designed ZnO:Cr front contact,PSCs device,and fabrication process are described.