Lightweight,ultra-flexible,and robust crosslinked transition metal carbide(Ti3C2 MXene)coated polyimide(PI)(C-MXene@PI)porous composites are manufactured via a scalable dip-coating followed by chemical crosslinking ap...Lightweight,ultra-flexible,and robust crosslinked transition metal carbide(Ti3C2 MXene)coated polyimide(PI)(C-MXene@PI)porous composites are manufactured via a scalable dip-coating followed by chemical crosslinking approach.In addition to the hydrophobicity,anti-oxidation and extreme-temperature stability,efficient utilization of the intrinsic conductivity of MXene,the interfacial polarization between MXene and PI,and the micrometer-sized pores of the composite foams are achieved.Consequently,the composites show a satisfactory X-band electromagnetic interference(EMI)shielding effectiveness of 22.5 to 62.5 dB at a density of 28.7 to 48.7 mg cm−3,leading to an excellent surface-specific SE of 21,317 dB cm^(2)g^(−1).Moreover,the composite foams exhibit excellent electrothermal performance as flexible heaters in terms of a prominent,rapid reproducible,and stable electrothermal effect at low voltages and superior heat performance and more uniform heat distribution compared with the commercial heaters composed of alloy plates.Furthermore,the composite foams are well attached on a human body to check their electromechanical sensing performance,demonstrating the sensitive and reliable detection of human motions as wearable sensors.The excellent EMI shielding performance and multifunctionalities,along with the facile and easy-to-scalable manufacturing techniques,imply promising perspectives of the porous C-MXene@PI composites in next-generation flexible electronics,aerospace,and smart devices.展开更多
Small peptide-based compounds have attracted an enormous interest as carrier molecules to selectively de- liver radionuclides to target tissues, sparing critical normal organs. When looking for "matched pairs&quo...Small peptide-based compounds have attracted an enormous interest as carrier molecules to selectively de- liver radionuclides to target tissues, sparing critical normal organs. When looking for "matched pairs" of radionuclides, suitable for radiolabeling of peptides for diagnosis and therapy, technetium and rhenium represent an almost ideal constellation. The important role of technetium-99m and Re-186/188 is based on the decay characteristics, suitable for tumor diagnosis and therapy. Tc-99m and Re-188 are readily available by either a 99Mo/99mTc or the 188W/188Re ra- dionuclide generator system. Furthermore, technetium and rhenium are chemically related and share structural as well as reactive similarities, which prompt an attractive "matched-pair" situation. This article shows an overview of 99mTc- and 186/188Re-radiolabeled peptides that have been tested for their potential use as imaging and therapeutic agents in oncological diseases.展开更多
Rare earth(RE)takes an irreplaceable role in various fields,especially the high-tech electronics industry,which is usually comparable to the vitamin of industry.In the development of electromagnetic wave(EMW)absorptio...Rare earth(RE)takes an irreplaceable role in various fields,especially the high-tech electronics industry,which is usually comparable to the vitamin of industry.In the development of electromagnetic wave(EMW)absorption materials,the participation of RE makes a significant contribution as well,and great progress has been made.Abundant researches have illuminated that the strategy of both doping RE elements and constructing RE oxide composites exhibited huge potential for the fabrication of high-efficiency EMW absorption materials.We believe a systematic summary will be highly desired for a comprehensive understanding and future development.In this review,we first summarized the research background,basic principles,and mechanisms of EMW absorption.Then,we classify the RE EMW absorption materials into RE-doped ferrites,RE-transition metal intermetallics,RE oxides,and other categories,view their current progress by typical studies,and expound their respective features,strengths,weaknesses,and absorption mechanisms.Finally,the current challenges and future outlook of RE EMW absorption materials are highlighted,in the hope of guidance for a sound future development.展开更多
We study the macromixing behavior of single and multi-orifice-impinging transverse(MOIT) jet mixers with crossflow, in particular, the overall mixing time and the back-splash mixing time of the injected flow with the ...We study the macromixing behavior of single and multi-orifice-impinging transverse(MOIT) jet mixers with crossflow, in particular, the overall mixing time and the back-splash mixing time of the injected flow with the crossflow, using the PLIF technique. It is found that for a given mixer configuration, there is a critical jet-tocrossflow velocity ratio rcat which the back-splash begins to occur. Further increase in the velocity ratio r leads to sharp increase in the back-splash mixing time, which can offset the intensification of the downstream mixing. The dimensionless overall mixing time decreases as r increases to reach either a plateau or a local minimum, and the corresponding r value represents the optimal velocity ratio roptfor the macromixing. The momentum ratio of the two liquid streams is a key factor determining rcand ropt. For a larger scale mixer, a higher momentum ratio is required to achieve the optimal macromixing with the minimum dimensionless overall mixing time.展开更多
Halogen chemistry constitutes an essential part in the industrial production of polymers and gains increasing attention as an attractive strategy to activate light alkanes that constitute natural gas. CeO2-based catal...Halogen chemistry constitutes an essential part in the industrial production of polymers and gains increasing attention as an attractive strategy to activate light alkanes that constitute natural gas. CeO2-based catalysts offer an exciting potential for advances in hydrogen halide recovery that enables a high efficiency of halogen-based processes for activation of small molecules. This review provides an overview of recently developed ceria-based catalysts in the context of polymer industry(polyvinyl chloride, polyurethanes, and polycarbonates) and activation of light hydrocarbons for natural gas upgrading. In addition, mechanistic insight and the challenges of ceria catalysts are provided, aiding the design of future catalytic materials and applications.展开更多
In the last three decades much effort has been devoted in process integration as a way to improve economic and environmental performance of chemical processes. Although the established frameworks have undergone consta...In the last three decades much effort has been devoted in process integration as a way to improve economic and environmental performance of chemical processes. Although the established frameworks have undergone constant refinement toward formulating and solving complicated process integration problems, less attention has been drawn to the problem of sequential applications of mass integration. This work addresses this problem by proposing an algorithm for optimal ordering of the process sinks in direct recycling problems, which is compatible with the typical mass integration formulation. The order consists in selecting the optimal sink at a specific integration step given the selection of the previous steps and the remaining process sources. Such order is identified through a succession of preemptive goal programming problems, namely of optimization problems characterized by more objectives at different priority levels. Indeed, the target for each sink is obtained by maximizing the total flow recycled from the available process sources to this sink and then minimizing the use of pure sources, starting from the purest one;the hierarchy is respected through a succession of linear optimization problems with a single objective function. While the conditional optimality of the algorithm holds always, a thorough statistical analysis including structured to random scenarios of process sources and process sinks shows how frequently the sequential ordering algorithm is outperformed with respect to the total recycled amount by a different selection of process sinks with the same cardinality. Two more case studies proving the usefulness of ordering the process sinks are illustrated. Extensions of the algorithm are also identified to cover more aspects of the process integration framework.展开更多
Pentacoordinated Al(Al~Ⅴ)species in silica-alumina are promising to promote the formation of acid sites or act as surface defects for tailoring single-atom catalysts.However,pentahedral coordination(Al~Ⅴ)is rarely o...Pentacoordinated Al(Al~Ⅴ)species in silica-alumina are promising to promote the formation of acid sites or act as surface defects for tailoring single-atom catalysts.However,pentahedral coordination(Al~Ⅴ)is rarely observed in conventionally prepared silica-alumina.Here,we show that high population and dispersion of Al~Ⅴ species on the surface of amorphous silica-alumina(ASA)can be achieved by means of flame spray pyrolysis.High resolution TEM/EDX,high magnetic-field NMR and DFT calculations are employed to characterize the structure of as-prepared ASAs.Solid-state ^(27)Al multi-quantum MAS NMR experiments show that most of the Al~Ⅴspecies are formed independently from the alumina phase and are accessible for vip molecules on the surface.Upon water adsorption,these Al~Ⅴ species are transformed to Al~Ⅵ species,structurally similar to surface Al~Ⅳ species,as confirmed by DFT calculations.The outstanding catalytic activity of as-synthesized ASA is demonstrated using the in situ H/D exchange reaction with deuterated benzene as an example.The Al~Ⅴ-rich ASA provides a much lower activation energy(～30 kJ/mol)than that reported for zeolite H-ZSM-5(～60 kJ/mol).The superior catalytic performance is attributed to the high Al~Ⅴcontent promoting the surface active sites in ASA.The knowledge gained on the synthesis of Al~Ⅴ-rich ASAs and the nature of aluminum coordination in these materials could pave the way to more efficient silica-alumina based catalysts.展开更多
A novel type of three-dimensional ultralight aerogel sphere,consisting of one-dimensional nanocellulose-derived carbon fibers and two-dimensional graphene layers,was prepared based on a developed drop-freeze-drying fo...A novel type of three-dimensional ultralight aerogel sphere,consisting of one-dimensional nanocellulose-derived carbon fibers and two-dimensional graphene layers,was prepared based on a developed drop-freeze-drying followed by carbonization approach.The nanofibrous carbon efficiently prevents the agglomeration of the graphene layers,which,in turn,reduces the shrinkage and maintains the structural stability of the hybrid carbon aerogel spheres.Consequently,the aerogel spheres showing an ultralow-density of 2.8 mg/cm^(3) and a porosity of 99.98%accomplish the tunable dielectric property and electromagnetic wave(EMW)absorption performance.The high-efficiency utilization of biomass-derived fibrous nanocarbon,graphene,the porous structure of the hybrid aerogel spheres leads to the excellent EMW absorption performance.The aerogel spheres display an effective absorption bandwidth of 6.16 GHz and a minimum reflection loss of−70.44 dB even at a filler loading of merely 3 wt.%,significantly outperforming that of other biomass-derived carbon-based EMW absorbing materials.This work offers a feasible,facile,scalable approach for fabricating high-performance and sustainable biomass-based aerogels,suggesting a tremendous application potential in EMW absorption and aerospace.展开更多
We evaluated bismuth doped cerium oxide catalysts for the continuous synthesis of dimethyl carbonate(DMC)from methanol and carbon dioxide in the absence of a dehydrating agent.Bi_(x)Ce_(1-x)O_(δ)nanocomposites of var...We evaluated bismuth doped cerium oxide catalysts for the continuous synthesis of dimethyl carbonate(DMC)from methanol and carbon dioxide in the absence of a dehydrating agent.Bi_(x)Ce_(1-x)O_(δ)nanocomposites of various compositions(x=0.06-0.24)were coated on a ceramic honeycomb and their structural and catalytic properties were examined.The incorporation of Bi species into the CeO_(2) lattice facilitated controlling of the surface population of oxygen vacancies,which is shown to play a crucial role in the mechanism of this reaction and is an important parameter for the design of ceria-based catalysts.The DMC production rate of the Bi_(x)Ce_(1-x)O_(δ) catalysts was found to be strongly enhanced with increasing Ov concentration.The concentration of oxygen vacancies exhibited a maximum for Bi_(0.12)Ce_(0.88)O_(δ),which afforded the highest DMC production rate.Long-term tests showed stable activity and selectivity of this catalyst over 45 h on-stream at 140°C and a gas-hourly space velocity of 2,880 mL·g_(cat)^(-1)·h^(-1).In-situ modulation excitation diffuse reflection Fourier transform infrared spectroscopy and first-principle calculations indicate that the DMC synthesis occurs through reaction of a bidentate carbonate intermediate with the activated methoxy(-OCH_(3))species.The activation of C0_(2) to form the bidentate carbonate intermediate on the oxygen vacancy sites is identified as highest energy barrier in the reaction pathway and thus is likely the rate-determining step.展开更多
Cu/ZrO2/SiO2 are efficient catalysts for the selective hydrogenation of CO2 to CH3OH. In order to understand the role of ZrO2 in these mixed-oxides based catalysts, in situ X-ray absorption spectroscopy has been carri...Cu/ZrO2/SiO2 are efficient catalysts for the selective hydrogenation of CO2 to CH3OH. In order to understand the role of ZrO2 in these mixed-oxides based catalysts, in situ X-ray absorption spectroscopy has been carried out on the Cu and Zr K-edge. Under reaction conditions, Cu remains metallic, while Zr is present in three types of coordination environment associated with 1) bulk ZrO2, 2) coordinatively saturated and 3) unsaturated Zr(Ⅳ) surface sites. The amount of coordinatively unsaturated Zr surface sites can be quantified by linear combination fit of reference X-Ray absorption near edge structure (XANES) spectra and its amount correlates with CH3OH formation rates, thus indicating the importance of Zr(Ⅳ) Lewis acid surface sites in driving the selectivity toward CH3OH. This finding is consistent with the proposed mechanism, where CO2 is hydrogenated at the interface between the Cu nanoparticles that split H2 and Zr(Ⅳ) surface sites that stabilizes reaction intermediates.展开更多
Monochromatization of high-harmonic sources has opened fascinating perspectives regarding time-resolved photoemission from all phases of matter.Such studies have invariably involved the use of spectral filters or spec...Monochromatization of high-harmonic sources has opened fascinating perspectives regarding time-resolved photoemission from all phases of matter.Such studies have invariably involved the use of spectral filters or spectrally dispersive optical components that are inherently lossy and technically complex.Here we present a new technique for the spectral selection of near-threshold harmonics and their spatial separation from the driving beams without any optical elements.We discover the existence of a narrow phase-matching gate resulting from the combination of the non-collinear generation geometry in an extended medium,atomic resonances and absorption.Our technique offers a filter contrast of up to 104 for the selected harmonics against the adjacent ones and offers multiple temporally synchronized beamlets in a single unified scheme.We demonstrate the selective generation of 133,80 or 56 nm femtosecond pulses from a 400-nm driver,which is specific to the target gas.These results open new pathways towards phase-sensitive multi-pulse spectroscopy in the vacuum-and extreme-ultraviolet,and frequencyselective output coupling from enhancement cavities.展开更多
With the aim of developing more stable Gd(Ⅲ)−porphyrin complexes,two types of ligands 1 and 2 with carboxylic acid anchors were synthesized.Due to the N-substituted pyridyl cation attached to the porphyrin core,these...With the aim of developing more stable Gd(Ⅲ)−porphyrin complexes,two types of ligands 1 and 2 with carboxylic acid anchors were synthesized.Due to the N-substituted pyridyl cation attached to the porphyrin core,these porphyrin ligands were highly water-soluble and formed the corresponding Gd(Ⅲ)chelates,Gd-1 and Gd-2.Gd-1 was sufficiently stable in neutral buffer,presumably due to the preferred conformation of the carboxylateterminated anchors connected to nitrogen in the meta position of the pyridyl group helping to stabilize Gd(Ⅲ)complexation by the porphyrin center.1H NMRD(nuclear magnetic relaxation dispersion)measurements on Gd-1 revealed high longitudinal water proton relaxivity(r_(1)=21.2 mM^(−1)s^(−1)at 60 MHz and 25℃),which originates from slow rotational motion resulting from aggregation in aqueous solution.Under visible light irradiation,Gd-1 showed extensive photoinduced DNA cleavage in line with efficient photoinduced singlet oxygen generation.Cell-based assays revealed no significant dark cytotoxicity of Gd-1,while it showed sufficient photocytotoxicity on cancer cell lines under visible light irradiation.These results indicate the potential of this Gd(Ⅲ)−porphyrin complex(Gd-1)as a core for the development of bifunctional systems acting as an efficient photodynamic therapy photosensitizer(PDT-PS)with magnetic resonance imaging(MRI)detection capabilities.展开更多
Routine clinical PET radiopharmaceuticals for the noninvasive imaging of brain receptors, transporters, and enzymes are commonly labeled with positron emitting nuclides such as carbon-11 or fluorine-18. Certain minima...Routine clinical PET radiopharmaceuticals for the noninvasive imaging of brain receptors, transporters, and enzymes are commonly labeled with positron emitting nuclides such as carbon-11 or fluorine-18. Certain minimal conditions need to be fulfilled for these PET ligands to be used as imaging agents in vivo. Some of these prerequisites are discussed and examples of the most useful clinical PET radiopharmaceuticals that have found application in the central nervous system are reviewed.展开更多
The molecular engineering of fluorescent organic/polymeric materials,specifically those emitting in the deep red to near-infrared spectrum,is vital for advancements in optoelectronics and biomedicine.Perylene diimide(...The molecular engineering of fluorescent organic/polymeric materials,specifically those emitting in the deep red to near-infrared spectrum,is vital for advancements in optoelectronics and biomedicine.Perylene diimide(PDI),a well-known fluorescent scaffold,offers high thermal and photophysical stability but suffers from fluorescence quenching in solid or aggregate states due to intenseπ-πinteractions.To mitigate this,simple and versatile methods for strong PDI aggregate emission without extensive synthetic demands are highly desirable but still lacking.Here,we report a straightforward strategy to enhance the solid-state emission of PDI by introducing certain degree of through-space charge transfer(TSCT)via controlled radical polymerization,which can efficiently distort the typical face-to-face PDI stacking,enabling greatly enhanced deep red emission.This is achieved by growing electron-donating star-shape styrenic(co)polymers from a multidirectional electron-accepting PDI initiator.The incorporation of polycyclic aromatic monomers further shifted the emission into the near-infrared region,albeit with a reduced intensity.Overall,the emission of the PDI-based TSCT polymers can be systematically manipulated by leveraging the balance between PDI stacking and the TSCT degree,as confirmed by both experimental study and theoretical calculations.Our approach circumvents complex synthetic procedures,offering highly emissive materials with large Stokes shifts and showing broad potential for optoelectronic technology.展开更多
Since the discovery of Li_(7)La_(3)Zr_(2)O_(12)(LLZO)as a solid-state electrolyte(SSE)capable of replacing flammable organic electrolytes in Li-ion batteries and enabling the use of Li-metal anodes,1 research into LLZ...Since the discovery of Li_(7)La_(3)Zr_(2)O_(12)(LLZO)as a solid-state electrolyte(SSE)capable of replacing flammable organic electrolytes in Li-ion batteries and enabling the use of Li-metal anodes,1 research into LLZO-based solid-state batteries(SSBs)has advanced at an impressive pace.展开更多
Three water-soluble Mn(III)-porphyrin complexes with cationic pyridyl side groups bearing COOH-or OH-terminated carbon chains in the meta or para positions have been synthesized as probes for both magnetic resonance i...Three water-soluble Mn(III)-porphyrin complexes with cationic pyridyl side groups bearing COOH-or OH-terminated carbon chains in the meta or para positions have been synthesized as probes for both magnetic resonance imaging(MRI)and photodynamic therapy(PDT).The complexes Mn-1,Mn-2,and Mn-3 are highly water-soluble,and their relaxivities range between 10 and 15 mM^(-1) s^(-1),at 20-80 MHz and 298 K,2-3 times higher than that of commercial Gd(III)-based agents.The complexes containing carboxylate(Mn-2)or alcoholic(Mn-3)side chains in the para position are endowed with higher relaxivities and have also shown efficient photoinduced DNA cleavage and singlet oxygen(^(1)O_(2))generation.Mn-3 with stronger photoinduced DNA cleavage has also revealed stabilizing and binding activities for G4 DNA,at a similar level as the known G4 binder Mn-TMPyP4.Nevertheless,the G4-binding activity of Mn-3 was nonspecific.Preliminary tests evidenced photocytotoxicity of Mn-3 on HeLa cells without a significant effect in the absence of light.Altogether,these results underline the potential of such water-soluble Mn(III)-porphyrins for the development of multimodal approaches combining MRI and PDT.展开更多
Design and exploitation of flame retardant polymers with high electrical conductivity are desired for polymer applications in electronics.Herein,a novel phosphorus-nitrogen intumescent flame retardant was synthesized ...Design and exploitation of flame retardant polymers with high electrical conductivity are desired for polymer applications in electronics.Herein,a novel phosphorus-nitrogen intumescent flame retardant was synthesized from pentaerythritol octahydrogen tetraphosphate,phenylphosphonyl dichloride,and aniline.Low-density polyethylene was combined with the flame retardant and multi-walled carbon nanotubes to form a nanocomposite material via a ball-milling and hot-pressing method.The electrical conductivity,mechanical properties,thermal performance,and flame retardancy of the composites were investigated using a four-point probe instrument,universal tensile machine,thermogravimetric analysis,and cone calorimeter tests,respectively.It was found that the addition of multi-walled carbon nanotubes can significantly improve the electrical conductivity and mechanical properties of the low-density polyethylene composites.Furthermore,the combination of multi-walled carbon nanotubes and phosphorus–nitrogen flame retardant remarkably enhances the flame retardancy of matrixes with an observed decrease of the peak heat release rate and total heat release of 49.8%and 51.9%,respectively.This study provides a new and effective methodology to substantially enhance the electrical conductivity and flame retardancy of polymers with an attractive prospect for polymer applications in electrical equipment.展开更多
Size hierarchy is a distinct feature of nanogold-catalysts as it can strongly affect their performance in various reactions. We developed a simple method to generate Au n S m nanoclusters of different sizes by thermal...Size hierarchy is a distinct feature of nanogold-catalysts as it can strongly affect their performance in various reactions. We developed a simple method to generate Au n S m nanoclusters of different sizes by thermal treatment of an Au144(PET)60 (PET: phenylethanethiol) parent cluster. These clusters, deposited on activated carbon, exhibit excellent catalytic performance in the hydrochlorination of acetylene. In-situ ultraviolet laser dissociation high-resolution mass spectrometry of the parent cluster in the presence of acetylene revealed a remarkable cluster size-dependence of acetylene adsorption, which is a crucial step in the hydrochlorination. Systematic density functional theory calculations of the reaction pathways on the differently-sized clusters provide deeper insight into the cluster size dependence of the adsorption energies of the reactants and afforded a scaling relationship between the adsorption energy of acetylene and the co-adsorption energies of the reactants (C_(2)H_(2) and HCl), which could enable a qualitative prediction of the optimal Au n S m cluster for the hydrochlorination of acetylene.展开更多
Chemistry on solid surfaces is central to many research areas of practical interest,such as synthesis,catalysis,electrochemistry,photochemistry,and materials science.A comprehensive understanding of the nanoscale on-s...Chemistry on solid surfaces is central to many research areas of practical interest,such as synthesis,catalysis,electrochemistry,photochemistry,and materials science.A comprehensive understanding of the nanoscale on-surface chemistry involved in these areas is important for establishing composition-structure-performance relationships.With the rapid development of tip-enhanced Raman spectroscopy(TERS),it has become possible to investigate physical and chemical processes on suitable surfaces at the nanoscale level and in real space.In this review,after a brief introduction of the background of onsurface chemistry and TERS,we systematically discuss the progress in the application of TERS in this field.Our focus is the applications of TERS to nanoscale coordination processes,decomposition reactions,polymerization processes,electrochemical reactions,catalytic chemistry,and functionalization chemistry on solid surfaces.We conclude by discussing the future challenges and development of TERS techniques and related applications in on-surface chemistry.展开更多
Digital light processing(DLP)of structurally complex poly(ethylene glycol)(PEG)hydrogels with high mechanical toughness represents a long-standing challenge in thefield of 3D printing.Here,we report a 3D printing appro...Digital light processing(DLP)of structurally complex poly(ethylene glycol)(PEG)hydrogels with high mechanical toughness represents a long-standing challenge in thefield of 3D printing.Here,we report a 3D printing approach for the high-resolution manufacturing of structurally complex and mechanically strong PEG hydrogels via heat-assisted DLP.Instead of using aqueous solutions of photo-crosslinkable monomers,PEG macromonomer melts werefirst printed in the absence of water,resulting in bulk PEG networks.Then,post-printing swelling of the printed networks was achieved in water,producing high-fidelity 3D hydrogels with complex structures.By employing a dual-macromonomer resin containing a PEG-based four-arm macrophotoinitiator,“all-PEG”hydrogel constructs were pro-duced with compressive toughness up to 1.3 MJ m^(-3).By this approach,porous 3D hydrogel scaffolds with trabecular-like architecture were fabricated,and the scaf-fold surface supported cell attachment and the formation of a monolayer mimicking bone-lining cells.This study highlights the promises of heat-assisted DLP of PEG photopolymers for hydrogel fabrication,which may accelerate the development of 3D tissue-like constructs for regenerative medicine.展开更多
基金support of the Qilu Young Scholar Program of Shandong University(No.31370082163127)the authors acknowledge funding from the support from the Chinese Scholarship Council(to NW,project#201709370040).
文摘Lightweight,ultra-flexible,and robust crosslinked transition metal carbide(Ti3C2 MXene)coated polyimide(PI)(C-MXene@PI)porous composites are manufactured via a scalable dip-coating followed by chemical crosslinking approach.In addition to the hydrophobicity,anti-oxidation and extreme-temperature stability,efficient utilization of the intrinsic conductivity of MXene,the interfacial polarization between MXene and PI,and the micrometer-sized pores of the composite foams are achieved.Consequently,the composites show a satisfactory X-band electromagnetic interference(EMI)shielding effectiveness of 22.5 to 62.5 dB at a density of 28.7 to 48.7 mg cm−3,leading to an excellent surface-specific SE of 21,317 dB cm^(2)g^(−1).Moreover,the composite foams exhibit excellent electrothermal performance as flexible heaters in terms of a prominent,rapid reproducible,and stable electrothermal effect at low voltages and superior heat performance and more uniform heat distribution compared with the commercial heaters composed of alloy plates.Furthermore,the composite foams are well attached on a human body to check their electromechanical sensing performance,demonstrating the sensitive and reliable detection of human motions as wearable sensors.The excellent EMI shielding performance and multifunctionalities,along with the facile and easy-to-scalable manufacturing techniques,imply promising perspectives of the porous C-MXene@PI composites in next-generation flexible electronics,aerospace,and smart devices.
文摘Small peptide-based compounds have attracted an enormous interest as carrier molecules to selectively de- liver radionuclides to target tissues, sparing critical normal organs. When looking for "matched pairs" of radionuclides, suitable for radiolabeling of peptides for diagnosis and therapy, technetium and rhenium represent an almost ideal constellation. The important role of technetium-99m and Re-186/188 is based on the decay characteristics, suitable for tumor diagnosis and therapy. Tc-99m and Re-188 are readily available by either a 99Mo/99mTc or the 188W/188Re ra- dionuclide generator system. Furthermore, technetium and rhenium are chemically related and share structural as well as reactive similarities, which prompt an attractive "matched-pair" situation. This article shows an overview of 99mTc- and 186/188Re-radiolabeled peptides that have been tested for their potential use as imaging and therapeutic agents in oncological diseases.
基金financially supported by the National Key R&D Program of China(No.2021YFB3502500)National Natural Science Foundation of China(Nos.22205131 and 22375115)+5 种基金Postdoctoral Innovation Project of Shandong Province(No.SDCX-ZG-202202015)Natural Science Foundation of Shandong Province(Nos.2022HYYQ-014 and ZR2023QE150)Provincial Key Research and Development Program of Shandong(No.2021ZLGX01)“20 Clauses about Colleges and Universities(new)”(Independent Training of Innovation Team)Program of Jinan(No.2021GXRC036)Qilu Young Scholar Program of Shandong University(No.31370082163127)Shenzhen municipal special fund for guiding local scientific and Technological Development(China 2021Szvup071)。
文摘Rare earth(RE)takes an irreplaceable role in various fields,especially the high-tech electronics industry,which is usually comparable to the vitamin of industry.In the development of electromagnetic wave(EMW)absorption materials,the participation of RE makes a significant contribution as well,and great progress has been made.Abundant researches have illuminated that the strategy of both doping RE elements and constructing RE oxide composites exhibited huge potential for the fabrication of high-efficiency EMW absorption materials.We believe a systematic summary will be highly desired for a comprehensive understanding and future development.In this review,we first summarized the research background,basic principles,and mechanisms of EMW absorption.Then,we classify the RE EMW absorption materials into RE-doped ferrites,RE-transition metal intermetallics,RE oxides,and other categories,view their current progress by typical studies,and expound their respective features,strengths,weaknesses,and absorption mechanisms.Finally,the current challenges and future outlook of RE EMW absorption materials are highlighted,in the hope of guidance for a sound future development.
基金Supported by the National Natural Science Foundation of China(21476048,21006011)the Fundamental Research Funds for the Central University(104.205.2.5)
文摘We study the macromixing behavior of single and multi-orifice-impinging transverse(MOIT) jet mixers with crossflow, in particular, the overall mixing time and the back-splash mixing time of the injected flow with the crossflow, using the PLIF technique. It is found that for a given mixer configuration, there is a critical jet-tocrossflow velocity ratio rcat which the back-splash begins to occur. Further increase in the velocity ratio r leads to sharp increase in the back-splash mixing time, which can offset the intensification of the downstream mixing. The dimensionless overall mixing time decreases as r increases to reach either a plateau or a local minimum, and the corresponding r value represents the optimal velocity ratio roptfor the macromixing. The momentum ratio of the two liquid streams is a key factor determining rcand ropt. For a larger scale mixer, a higher momentum ratio is required to achieve the optimal macromixing with the minimum dimensionless overall mixing time.
文摘Halogen chemistry constitutes an essential part in the industrial production of polymers and gains increasing attention as an attractive strategy to activate light alkanes that constitute natural gas. CeO2-based catalysts offer an exciting potential for advances in hydrogen halide recovery that enables a high efficiency of halogen-based processes for activation of small molecules. This review provides an overview of recently developed ceria-based catalysts in the context of polymer industry(polyvinyl chloride, polyurethanes, and polycarbonates) and activation of light hydrocarbons for natural gas upgrading. In addition, mechanistic insight and the challenges of ceria catalysts are provided, aiding the design of future catalytic materials and applications.
文摘In the last three decades much effort has been devoted in process integration as a way to improve economic and environmental performance of chemical processes. Although the established frameworks have undergone constant refinement toward formulating and solving complicated process integration problems, less attention has been drawn to the problem of sequential applications of mass integration. This work addresses this problem by proposing an algorithm for optimal ordering of the process sinks in direct recycling problems, which is compatible with the typical mass integration formulation. The order consists in selecting the optimal sink at a specific integration step given the selection of the previous steps and the remaining process sources. Such order is identified through a succession of preemptive goal programming problems, namely of optimization problems characterized by more objectives at different priority levels. Indeed, the target for each sink is obtained by maximizing the total flow recycled from the available process sources to this sink and then minimizing the use of pure sources, starting from the purest one;the hierarchy is respected through a succession of linear optimization problems with a single objective function. While the conditional optimality of the algorithm holds always, a thorough statistical analysis including structured to random scenarios of process sources and process sinks shows how frequently the sequential ordering algorithm is outperformed with respect to the total recycled amount by a different selection of process sinks with the same cardinality. Two more case studies proving the usefulness of ordering the process sinks are illustrated. Extensions of the algorithm are also identified to cover more aspects of the process integration framework.
基金the financial supports by Australian Research Council Discovery Projects (DP150103842)Discovery Earlier Career Research Project (DE190101618)+1 种基金the Faculty's MCR Scheme, Energy and Materials Clusters at the University of Sydneythe support by the National Natural Science Foundation of China (21522310, 21473244 and 21210005)
文摘Pentacoordinated Al(Al~Ⅴ)species in silica-alumina are promising to promote the formation of acid sites or act as surface defects for tailoring single-atom catalysts.However,pentahedral coordination(Al~Ⅴ)is rarely observed in conventionally prepared silica-alumina.Here,we show that high population and dispersion of Al~Ⅴ species on the surface of amorphous silica-alumina(ASA)can be achieved by means of flame spray pyrolysis.High resolution TEM/EDX,high magnetic-field NMR and DFT calculations are employed to characterize the structure of as-prepared ASAs.Solid-state ^(27)Al multi-quantum MAS NMR experiments show that most of the Al~Ⅴspecies are formed independently from the alumina phase and are accessible for vip molecules on the surface.Upon water adsorption,these Al~Ⅴ species are transformed to Al~Ⅵ species,structurally similar to surface Al~Ⅳ species,as confirmed by DFT calculations.The outstanding catalytic activity of as-synthesized ASA is demonstrated using the in situ H/D exchange reaction with deuterated benzene as an example.The Al~Ⅴ-rich ASA provides a much lower activation energy(～30 kJ/mol)than that reported for zeolite H-ZSM-5(～60 kJ/mol).The superior catalytic performance is attributed to the high Al~Ⅴcontent promoting the surface active sites in ASA.The knowledge gained on the synthesis of Al~Ⅴ-rich ASAs and the nature of aluminum coordination in these materials could pave the way to more efficient silica-alumina based catalysts.
基金the National Key R&D Program of China(No.2021YFB3502500)the Natural Science Foundation of Shandong Province(Nos.2022HYYQ-014 and ZR2016BM16)+6 种基金the New 20 Funded Programs for universities of Jinan(No.2021GXRC036)the Provincial Key Research and Development Program of Shandong(Nos.2019JZZY010312 and 2021ZLGX01)the National Natural Science Foundation of China(No.22205131)the Natural Science Foundation of Jiangsu Province(No.BK20220274)the Shenzhen Municipal Special Fund for Guiding Local Scientific and Technological Development(No.2021Szvup071)the Joint Laboratory project of Electromagnetic Structure Technology(No.637-2022-70-F-037)the Qilu Young Scholar Program of Shandong University(No.31370082163127).
文摘A novel type of three-dimensional ultralight aerogel sphere,consisting of one-dimensional nanocellulose-derived carbon fibers and two-dimensional graphene layers,was prepared based on a developed drop-freeze-drying followed by carbonization approach.The nanofibrous carbon efficiently prevents the agglomeration of the graphene layers,which,in turn,reduces the shrinkage and maintains the structural stability of the hybrid carbon aerogel spheres.Consequently,the aerogel spheres showing an ultralow-density of 2.8 mg/cm^(3) and a porosity of 99.98%accomplish the tunable dielectric property and electromagnetic wave(EMW)absorption performance.The high-efficiency utilization of biomass-derived fibrous nanocarbon,graphene,the porous structure of the hybrid aerogel spheres leads to the excellent EMW absorption performance.The aerogel spheres display an effective absorption bandwidth of 6.16 GHz and a minimum reflection loss of−70.44 dB even at a filler loading of merely 3 wt.%,significantly outperforming that of other biomass-derived carbon-based EMW absorbing materials.This work offers a feasible,facile,scalable approach for fabricating high-performance and sustainable biomass-based aerogels,suggesting a tremendous application potential in EMW absorption and aerospace.
基金supported by the National Natural Science Foundation of China(Nos.21773189 and 11974195)Department of Science and Technology of Sichuan Province(19ZDZX0113)Liaoning Revitalization Talents Program(XLYC1807121).
文摘We evaluated bismuth doped cerium oxide catalysts for the continuous synthesis of dimethyl carbonate(DMC)from methanol and carbon dioxide in the absence of a dehydrating agent.Bi_(x)Ce_(1-x)O_(δ)nanocomposites of various compositions(x=0.06-0.24)were coated on a ceramic honeycomb and their structural and catalytic properties were examined.The incorporation of Bi species into the CeO_(2) lattice facilitated controlling of the surface population of oxygen vacancies,which is shown to play a crucial role in the mechanism of this reaction and is an important parameter for the design of ceria-based catalysts.The DMC production rate of the Bi_(x)Ce_(1-x)O_(δ) catalysts was found to be strongly enhanced with increasing Ov concentration.The concentration of oxygen vacancies exhibited a maximum for Bi_(0.12)Ce_(0.88)O_(δ),which afforded the highest DMC production rate.Long-term tests showed stable activity and selectivity of this catalyst over 45 h on-stream at 140°C and a gas-hourly space velocity of 2,880 mL·g_(cat)^(-1)·h^(-1).In-situ modulation excitation diffuse reflection Fourier transform infrared spectroscopy and first-principle calculations indicate that the DMC synthesis occurs through reaction of a bidentate carbonate intermediate with the activated methoxy(-OCH_(3))species.The activation of C0_(2) to form the bidentate carbonate intermediate on the oxygen vacancy sites is identified as highest energy barrier in the reaction pathway and thus is likely the rate-determining step.
基金E.L.,K.L.,P.W.,and S.T.are supported by the SCCER-Heat and Energy Storage program
文摘Cu/ZrO2/SiO2 are efficient catalysts for the selective hydrogenation of CO2 to CH3OH. In order to understand the role of ZrO2 in these mixed-oxides based catalysts, in situ X-ray absorption spectroscopy has been carried out on the Cu and Zr K-edge. Under reaction conditions, Cu remains metallic, while Zr is present in three types of coordination environment associated with 1) bulk ZrO2, 2) coordinatively saturated and 3) unsaturated Zr(Ⅳ) surface sites. The amount of coordinatively unsaturated Zr surface sites can be quantified by linear combination fit of reference X-Ray absorption near edge structure (XANES) spectra and its amount correlates with CH3OH formation rates, thus indicating the importance of Zr(Ⅳ) Lewis acid surface sites in driving the selectivity toward CH3OH. This finding is consistent with the proposed mechanism, where CO2 is hydrogenated at the interface between the Cu nanoparticles that split H2 and Zr(Ⅳ) surface sites that stabilizes reaction intermediates.
基金support from a starting grant(project No.307270-ATTOSCOPE)of the European Research Councilthe Swiss National Science Foundation via the National Centre of Competence in Research Molecular Ultrafast Science and Technology.
文摘Monochromatization of high-harmonic sources has opened fascinating perspectives regarding time-resolved photoemission from all phases of matter.Such studies have invariably involved the use of spectral filters or spectrally dispersive optical components that are inherently lossy and technically complex.Here we present a new technique for the spectral selection of near-threshold harmonics and their spatial separation from the driving beams without any optical elements.We discover the existence of a narrow phase-matching gate resulting from the combination of the non-collinear generation geometry in an extended medium,atomic resonances and absorption.Our technique offers a filter contrast of up to 104 for the selected harmonics against the adjacent ones and offers multiple temporally synchronized beamlets in a single unified scheme.We demonstrate the selective generation of 133,80 or 56 nm femtosecond pulses from a 400-nm driver,which is specific to the target gas.These results open new pathways towards phase-sensitive multi-pulse spectroscopy in the vacuum-and extreme-ultraviolet,and frequencyselective output coupling from enhancement cavities.
基金supported in part by the SNF,Strategic Japanese-Swiss Science and Technology Program(IZLJZ2_183660,Y.Y.)JSPS under the Joint Research Program implemented in association with SNF(20191508,H.M.and N.Y.-S.)+3 种基金the SNF Project Funding(205321_173018,Y.Y.)the ETH Research Grant(ETH-21_15-2ETH-36_20-2,Y.Y.)JSPS KAKENHI(Grantin-Aid for Scientific Research[A],6251004,H.M.,Grants-in-Aid for Scientific Research on Innovative Areas,21H00264,22H04707,H.M.,Grant-in-Aid for Scientific Research[C],15K07164,N.Y.-S.).
文摘With the aim of developing more stable Gd(Ⅲ)−porphyrin complexes,two types of ligands 1 and 2 with carboxylic acid anchors were synthesized.Due to the N-substituted pyridyl cation attached to the porphyrin core,these porphyrin ligands were highly water-soluble and formed the corresponding Gd(Ⅲ)chelates,Gd-1 and Gd-2.Gd-1 was sufficiently stable in neutral buffer,presumably due to the preferred conformation of the carboxylateterminated anchors connected to nitrogen in the meta position of the pyridyl group helping to stabilize Gd(Ⅲ)complexation by the porphyrin center.1H NMRD(nuclear magnetic relaxation dispersion)measurements on Gd-1 revealed high longitudinal water proton relaxivity(r_(1)=21.2 mM^(−1)s^(−1)at 60 MHz and 25℃),which originates from slow rotational motion resulting from aggregation in aqueous solution.Under visible light irradiation,Gd-1 showed extensive photoinduced DNA cleavage in line with efficient photoinduced singlet oxygen generation.Cell-based assays revealed no significant dark cytotoxicity of Gd-1,while it showed sufficient photocytotoxicity on cancer cell lines under visible light irradiation.These results indicate the potential of this Gd(Ⅲ)−porphyrin complex(Gd-1)as a core for the development of bifunctional systems acting as an efficient photodynamic therapy photosensitizer(PDT-PS)with magnetic resonance imaging(MRI)detection capabilities.
文摘Routine clinical PET radiopharmaceuticals for the noninvasive imaging of brain receptors, transporters, and enzymes are commonly labeled with positron emitting nuclides such as carbon-11 or fluorine-18. Certain minimal conditions need to be fulfilled for these PET ligands to be used as imaging agents in vivo. Some of these prerequisites are discussed and examples of the most useful clinical PET radiopharmaceuticals that have found application in the central nervous system are reviewed.
基金supported by Swiss National Science Foundation(190313)Fondation Claude et Giuliana(1-005137)the Australian Research Council(ARC)under the Centre of Excellence Scheme(CE170100026)。
文摘The molecular engineering of fluorescent organic/polymeric materials,specifically those emitting in the deep red to near-infrared spectrum,is vital for advancements in optoelectronics and biomedicine.Perylene diimide(PDI),a well-known fluorescent scaffold,offers high thermal and photophysical stability but suffers from fluorescence quenching in solid or aggregate states due to intenseπ-πinteractions.To mitigate this,simple and versatile methods for strong PDI aggregate emission without extensive synthetic demands are highly desirable but still lacking.Here,we report a straightforward strategy to enhance the solid-state emission of PDI by introducing certain degree of through-space charge transfer(TSCT)via controlled radical polymerization,which can efficiently distort the typical face-to-face PDI stacking,enabling greatly enhanced deep red emission.This is achieved by growing electron-donating star-shape styrenic(co)polymers from a multidirectional electron-accepting PDI initiator.The incorporation of polycyclic aromatic monomers further shifted the emission into the near-infrared region,albeit with a reduced intensity.Overall,the emission of the PDI-based TSCT polymers can be systematically manipulated by leveraging the balance between PDI stacking and the TSCT degree,as confirmed by both experimental study and theoretical calculations.Our approach circumvents complex synthetic procedures,offering highly emissive materials with large Stokes shifts and showing broad potential for optoelectronic technology.
基金funding from the Swiss National Science Foundation(No.10.003.732)and Innosuisse(Grant No.58207.1).
文摘Since the discovery of Li_(7)La_(3)Zr_(2)O_(12)(LLZO)as a solid-state electrolyte(SSE)capable of replacing flammable organic electrolytes in Li-ion batteries and enabling the use of Li-metal anodes,1 research into LLZO-based solid-state batteries(SSBs)has advanced at an impressive pace.
基金supported in part by SNF Strategic Japanese-Swiss Science and Technology Program(IZLJZ2_183660,YY)JSPS,under the Joint Research Program implemented in association with SNF(20191508,H.M.and N.Y.-S),SNF Project Funding(205321_173018,Y.Y.)+4 种基金ETH Research Grants(ETH-21_15-2ETH-36_20-2,Y.Y.)JSPS KAKENHI(Grant-in-Aid for Scientific Research[A],6251004,H.M.Grants-in-Aid for Scientific Research on Innovative Areas,21H00264,22H04707,H.M.Grant-in-Aid for Scientific Research[C],15K07164,N.Y.-S).
文摘Three water-soluble Mn(III)-porphyrin complexes with cationic pyridyl side groups bearing COOH-or OH-terminated carbon chains in the meta or para positions have been synthesized as probes for both magnetic resonance imaging(MRI)and photodynamic therapy(PDT).The complexes Mn-1,Mn-2,and Mn-3 are highly water-soluble,and their relaxivities range between 10 and 15 mM^(-1) s^(-1),at 20-80 MHz and 298 K,2-3 times higher than that of commercial Gd(III)-based agents.The complexes containing carboxylate(Mn-2)or alcoholic(Mn-3)side chains in the para position are endowed with higher relaxivities and have also shown efficient photoinduced DNA cleavage and singlet oxygen(^(1)O_(2))generation.Mn-3 with stronger photoinduced DNA cleavage has also revealed stabilizing and binding activities for G4 DNA,at a similar level as the known G4 binder Mn-TMPyP4.Nevertheless,the G4-binding activity of Mn-3 was nonspecific.Preliminary tests evidenced photocytotoxicity of Mn-3 on HeLa cells without a significant effect in the absence of light.Altogether,these results underline the potential of such water-soluble Mn(III)-porphyrins for the development of multimodal approaches combining MRI and PDT.
基金the National Natural Science Foundation of China(Grant Nos.21663015,21908031 and 51603096)Scientific Research Funds of Yunnan Education Department(Grant No.2021Y111).
文摘Design and exploitation of flame retardant polymers with high electrical conductivity are desired for polymer applications in electronics.Herein,a novel phosphorus-nitrogen intumescent flame retardant was synthesized from pentaerythritol octahydrogen tetraphosphate,phenylphosphonyl dichloride,and aniline.Low-density polyethylene was combined with the flame retardant and multi-walled carbon nanotubes to form a nanocomposite material via a ball-milling and hot-pressing method.The electrical conductivity,mechanical properties,thermal performance,and flame retardancy of the composites were investigated using a four-point probe instrument,universal tensile machine,thermogravimetric analysis,and cone calorimeter tests,respectively.It was found that the addition of multi-walled carbon nanotubes can significantly improve the electrical conductivity and mechanical properties of the low-density polyethylene composites.Furthermore,the combination of multi-walled carbon nanotubes and phosphorus–nitrogen flame retardant remarkably enhances the flame retardancy of matrixes with an observed decrease of the peak heat release rate and total heat release of 49.8%and 51.9%,respectively.This study provides a new and effective methodology to substantially enhance the electrical conductivity and flame retardancy of polymers with an attractive prospect for polymer applications in electrical equipment.
基金financial support by the National Natural Science Foundation of China(No.22172167).
文摘Size hierarchy is a distinct feature of nanogold-catalysts as it can strongly affect their performance in various reactions. We developed a simple method to generate Au n S m nanoclusters of different sizes by thermal treatment of an Au144(PET)60 (PET: phenylethanethiol) parent cluster. These clusters, deposited on activated carbon, exhibit excellent catalytic performance in the hydrochlorination of acetylene. In-situ ultraviolet laser dissociation high-resolution mass spectrometry of the parent cluster in the presence of acetylene revealed a remarkable cluster size-dependence of acetylene adsorption, which is a crucial step in the hydrochlorination. Systematic density functional theory calculations of the reaction pathways on the differently-sized clusters provide deeper insight into the cluster size dependence of the adsorption energies of the reactants and afforded a scaling relationship between the adsorption energy of acetylene and the co-adsorption energies of the reactants (C_(2)H_(2) and HCl), which could enable a qualitative prediction of the optimal Au n S m cluster for the hydrochlorination of acetylene.
基金We acknowledge financial support from the ERC program(Grant No.741431-2DNanoSpec).
文摘Chemistry on solid surfaces is central to many research areas of practical interest,such as synthesis,catalysis,electrochemistry,photochemistry,and materials science.A comprehensive understanding of the nanoscale on-surface chemistry involved in these areas is important for establishing composition-structure-performance relationships.With the rapid development of tip-enhanced Raman spectroscopy(TERS),it has become possible to investigate physical and chemical processes on suitable surfaces at the nanoscale level and in real space.In this review,after a brief introduction of the background of onsurface chemistry and TERS,we systematically discuss the progress in the application of TERS in this field.Our focus is the applications of TERS to nanoscale coordination processes,decomposition reactions,polymerization processes,electrochemical reactions,catalytic chemistry,and functionalization chemistry on solid surfaces.We conclude by discussing the future challenges and development of TERS techniques and related applications in on-surface chemistry.
基金financial support(Sinergia No.177178 and research project No.315230_197644/1)financial support from the Swiss National Science Foundation(No.190345,188522 and 206501)financial support from China Scholarship Council(CSC,No.202006790027).
文摘Digital light processing(DLP)of structurally complex poly(ethylene glycol)(PEG)hydrogels with high mechanical toughness represents a long-standing challenge in thefield of 3D printing.Here,we report a 3D printing approach for the high-resolution manufacturing of structurally complex and mechanically strong PEG hydrogels via heat-assisted DLP.Instead of using aqueous solutions of photo-crosslinkable monomers,PEG macromonomer melts werefirst printed in the absence of water,resulting in bulk PEG networks.Then,post-printing swelling of the printed networks was achieved in water,producing high-fidelity 3D hydrogels with complex structures.By employing a dual-macromonomer resin containing a PEG-based four-arm macrophotoinitiator,“all-PEG”hydrogel constructs were pro-duced with compressive toughness up to 1.3 MJ m^(-3).By this approach,porous 3D hydrogel scaffolds with trabecular-like architecture were fabricated,and the scaf-fold surface supported cell attachment and the formation of a monolayer mimicking bone-lining cells.This study highlights the promises of heat-assisted DLP of PEG photopolymers for hydrogel fabrication,which may accelerate the development of 3D tissue-like constructs for regenerative medicine.
