Identification of origin of insulating polymer maneuvered photoredox catalysis

Solid non-conjugated polymers have long been regarded as insulators due to deficiency of delocalizedπelectrons along the molecular chain framework.Up to date,origin of insulating polymer regulated charge transfer has not yet been uncovered.In this work,we unleash the root origin of charge transport capability of insulating polymer in photocatalysis.We ascertain that insulating polymer plays crucial roles in fine tuning of electronic structure of transition metal chalcogenides(TMCs),which mainly include altering surface electron density of TMCs for accelerating charge transport kinetics,triggering the generation of defect over TMCs for prolonging carrier lifetime,and acting as hole-trapping mediator for retarding charge recombination.These synergistic roles contribute to the charge transfer of insulating polymer.Our work opens a new vista of utilizing solid insulating polymers for maneuvering charge transfer toward solar energy conversion.

Thermal Performance Analysis of Plaster Reinforced with Raffia Vinifera Particles for Use as Insulating Materials in Building

The present study focuses on the formulation of new composite consisting of plaster and raffia vinifera particle (RVP) with the purpose to reducing energy consumption. The aim of this study is to test this new compound as an insulating eco-material in building in a tropical climate. The composites samples were developed by mixing plaster with raffia vinifera particles (RVP) using three different sizes (1.6 mm, 2.5 mm and 4 mm). The effects of four different RVP incorporations rates (i.e., 0wt%, 5wt%;10wt%;15wt%) on physical, thermal, mechanicals properties of the composites were investigated. In addition, the use of the raffia vinifera particles and plaster based composite material as building envelopes thermal insulation material is studied by the habitable cell thermal behavior instrumentation. The results indicate that the incorporation of raffia vinifera particle leads to improve the new composite physical, mechanical and thermal properties. And the parametric analysis reveals that the sampling rate and the size of raffia vinifera particles are the most decisive factor to impact these properties, and to decreases in the thermal conductivity which leads to an improvement to the thermal resistance and energy savings. The best improvement of plaster composite was obtained at the raffia vinifera particles size between 2.5 and 4.0 mm loading of 5wt% (C95P5R) with a good ratio of thermo-physical-mechanical properties. Additionally, the habitable cell experimental thermal behavior, with the new raffia vinifera particles and plaster-based composite as thermal insulating material for building walls, gives an average damping of 4°C and 5.8°C in the insulated house interior environment respectively for cold and hot cases compared to the outside environment and the uninsulated house interior environment. The current study highlights that this mixture gives the new composite thermal insulation properties applicable in the eco-construction of habitats in tropical environments.

Surface doping manipulation of the insulating ground states in Ta_(2)Pd_(3)Te_(5) and Ta_(2)Ni_(3)Te_(5)

Manipulating emergent quantum phenomena is a key issue for understanding the underlying physics and contributing to possible applications.Here we study the evolution of insulating ground states of Ta_(2)Pu_(3)Te_(5) and Ta_(2)Ni_(3)Te_(5) under in-situ surface potassium deposition via angle-resolved photoemission spectroscopy.Our results confirm the excitonic insulator character of Ta_(2)d_(3)Te_(5).Upon surface doping,the size of its global gap decreases obviously.After a deposition time of more than 7 min,the potassium atoms induce a metal-insulator phase transition and make the system recover to a normal state.In contrast,our results show that the isostructural compound Ta_(2)Ni_(3)Te_(5) is a conventional insulator.The size of its global gap decreases upon surface doping,but persists positive throughout the doping process.Our results not only confirm the excitonic origin of the band gap in Ta_(2)Pd_(3)Te_(5),but also offer an effective method for designing functional quantum devices in the future.

A low-frequency and broadband wave-insulating vibration isolator based on plate-shaped metastructures

A metamaterial vibration isolator,termed as wave-insulating isolator,is proposed,which preserves enough load-bearing capability and offers ultra-low and broad bandgaps for greatly enhanced wave insulation.It consists of plate-shaped metacells,whose symmetric and antisymmetric local resonant modes offer several low and broad mode bandgaps although the complete bandgap remains high and narrow.The bandgap mechanisms,vibration isolation properties,effects of key parameters,and robustness to complex conditions are clarified.As experimentally demonstrated,the wave-insulating isolator can improve the vibration insulation in the ranges of[50 Hz,180 Hz]and[260 Hz,400 Hz]by 15 dB and 25 dB,respectively,in contrast to the conventional isolator with the same first resonant frequency.

Field induced Chern insulating states in twisted monolayer–bilayer graphene

Unraveling the mechanism underlying topological phases, notably the Chern insulators(Ch Is) in strong correlated systems at the microscopy scale, has captivated significant research interest. Nonetheless, Ch Is harboring topological information have not always manifested themselves, owing to the constraints imposed by displacement fields in certain experimental configurations. In this study, we employ density-tuned scanning tunneling microscopy(DT-STM) to investigate the Ch Is in twisted monolayer–bilayer graphene(t MBG). At zero magnetic field, we observe correlated metallic states.While under a magnetic field, a metal–insulator transition happens and an integer Ch I is formed emanating from the filling index s = 3 with a Chern number C = 1. Our results underscore the pivotal role of magnetic fields as a powerful probe for elucidating topological phases in twisted Van der Waals heterostructures.

Preparation of Semi-Insulating Material by Annealing Undoped InP

Semi insulating (SI) InP wafers of 50 and 75mm in diameter can be obtained by annealing of undoped liquid encapsulated Czochralski (LEC) InP at 930℃ for 80h.The annealing ambient can be pure phosphorus (PP) or iron phosphide (IP).The IP SI InP wafers have good electrical parameters and uniformity of whole wafer.However,PP SI InP wafers exhibit poor uniformity and electrical parameters.Photoluminescence which is subtle to deep defect appears in IP annealed semi insulating InP.Traps in annealed SI InP are detected by the spectroscopy of photo induced current transient.The results indicate that there are fewer traps in IP annealed undoped SI InP than those in as grown Fe doped and PP undoped SI InP.The formation mechanism of deep defects in annealed undoped InP is discussed.

Superinsulating BNNS/PVA Composite Aerogels with High Solar Reflectance for Energy-Efficient Buildings

With the mandate of worldwide carbon neutralization,pursuing comfortable living environment while consuming less energy is an enticing and unavoidable choice.Novel composite aerogels with super thermal insulation and high sunlight reflection are developed for energy-efficient buildings.A solvent-assisted freeze-casting strategy is used to produce boron nitride nanosheet/polyvinyl alcohol(BNNS/PVA)composite aerogels with a tailored alignment channel structure.The effects of acetone and BNNS fillers on microstructures and multifunctional properties of aerogels are investigated.The acetone in the PVA suspension enlarges the cell walls to suppress the shrinkage,giving rise to a lower density and a higher porosity,accompanied with much diminished heat conduction throughout the whole product.The addition of BNNS fillers creates whiskers in place of disconnected transverse ligaments between adjacent cell walls,further ameliorating the thermal insulation transverse to the cell wall direction.The resultant BNNS/PVA aerogel delivers an ultralow thermal conductivity of 23.5 mW m^(−1) K^(−1) in the transverse direction.The superinsulating aerogel presents both an infrared stealthy capability and a high solar reflectance of 93.8%over the whole sunlight wave-length,far outperforming commercial expanded polystyrene foams with reflective coatings.The anisotropic BNNS/PVA composite aerogel presents great potential for application in energy-saving buildings.

Fabrication and Thermal Insulating Properties of ITO/PVB Nanocomposites for Energy Saving Glass

Chemical co-precipitation method was used to synthesize tin-doped indium oxide（ITO）nanoparticles,and the subsequent solution co-blend was employed to fabricate ITO/PVB nanocomposites.UV（Ultra-violet）-Vis（Visible）-NIR（Near Infrared） spectra show that the addition of ITO nano particles can significantly enhance the thermal insulating efficiency of ITO/PVB nanocomposites.With increasing ITO content,the thermal insulating efficiency is increased.UV is almost fully absorbed by all ITO/PVB nanocomposites.Vis transmittance-haze spectra reveal that ITO/PVB nanocomposites exhibit higher Vis transmittance over 71.3%and lower haze below 2%when ITO content is in the range of 0.1 wt%-0.7 wt%.The UV-Vis-NIR spectroscopy shows that,under the premise of over 70%transmittance to the visible light,the screening effect of the NIR can be enhanced by 80%with 0.7%ITO/PVB nanocomposite membrane compared with the undoped PVB.The thermal insulating tests indicate that,in comparison with the pure PVB film,nanocomposite films with 0.1 wt%-0.9 wt%ITO can reduce temperature by 3-8 ℃.The results show that this novel nanocomposite can be used for energy-saving glass.

Fabrication and Thermal Insulating Properties of ATO/PVB Nanocomposites for Energy Saving Glass

The pechini method was used to synthesize antimony-doped tin oxide （ATO） nanoparticles, and the subsequent solution co-blend was employed to fabricate ATO/PVB nanocomposites. Uv-Vis-NIR spectra show that the addition ofATO nano particles can significantly enhance the thermal insulating efficiency of ATO/PVB nanocomposites. With the increase of ATO content, the thermal insulating efficiency is increased. Uv is almost fully absorbed by all ATO/PVB nanocomposites. Vis transmittance-haze spectra reveal that ATO/ PVB nanocomposites exhibit higher Vis transmittance of over 72.7% and lower haze of below 2% when ATO content is in the range of 0.1 wt%-0.5 wt%. The thermal insulating tests indicate that in comparison with the pure PVB film, nanocomposite films with 0.1 wt%-0.5 wt% ATO can reduce temperature of 1-3 ℃, suggesting that this novel nanocomposite can be used for energy-saving glass.

Preparation and characterization of carbonyl iron soft magnetic composites with magnesioferrite insulating coating layer

Spherical carbonyl iron(Fe)powders were coated with magnesioferrite(MgFe2O4)insulating coating layer and then mixed with epoxy-modified silicone resin(ESR).Soft magnetic composites(SMCs)were fabricated by compaction of the coated powders and annealing treatment.Transmission electron microscopy(TEM),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),X-ray diffractometry(XRD)and X-ray photoelectron spectroscopy(XPS)revealed that the MgFe2O4 layer was coated on the surface of the iron powders.The magnetic properties of SMCs were determined using a vibrating sample magnetometer and an auto testing system for magnetic materials.The results showed that the SMCs prepared at 800 MPa and 550℃ exhibited a significant core loss of 167.5 W/kg at 100 kHz and 50 mT.

Research on non-steam-cured and non-fired fly-ash thermal insulating materials

A thermal insulating material is synthesized via a non-steam-cured and non-fired route by using fly-ash, sorel cement and hydrogen peroxide solution as raw material. Properties such as apparent density, compressive strength, bending strength, thermal conductivity, water resistance, and thermal tolerance of this matrial are studied, some influencing factors on its performance discussed. This material has an apparent density of 360 kg/m^3, a compressive strength of 1.86 MPa, a thermal conduction coefficient of 0.072 W/（m·K）, a softening coefficient of 0.55, and a thermal tolerant temperature of 300 ℃. Test results show that this material is light in weight, of high strength, and good thermal insulation. In addition, neither steam-curing nor sintering is needed in producing it. Further more, large amount of fly ash is used in this material, making it a low cost and environment-friendly building material.

Analysis of MHD Pressure Drop in Liquid LiPb Flow in Chinese ITER DFLL-TBM with Insulating Coating

Magnetohydrodynamic （MHD） pressure drop in the Chinese Dual Functional Liquid Lithium-lead Test Blanket Module （DFLL-TBM） proposed for ITER is discussed in this paper. Electrical insulation between the coolant channel surfaces and the liquid metal is required to reduce the MHD pressure drop to a manageable level. Insulation can be provided by a thin insulating coating, such as Al2O3, which can also serve as a tritium barrier layer, at the channel surfaces in contact with LiPb. The coating＇s effectiveness for reducing the MHD pressure drop is analysed through three-dimensional numerical simulation. A MHD-based commercial computational fluid dynamic （CFD） software FLUENT is used to simulate the LiPb flow. The effect on the MHD pressure drop due to cracks or faults in the coating layer is also considered. The insulating performance requirement for the coating material in DFLL-TBM design is proposed according to the analysis.

Preparation and Performance of Graphene Oxide Modified Polyurethane Thermal Conductive Insulating Adhesive

A novel graphene oxide (GO) modified polyurethane thermal conductive insulating adhesive with small addition and excellent insulation properties was prepared by in-situ polymerization using GO as thermal conductive filler.The effects of GO content on the mechanical performance,thermal conductivity,thermal stability and insulation properties of the modified polyurethane adhesive were studied.The results showed that the tensile strength and elongation at break of polyurethane adhesive increased at first and then decreased with the increase of GO content.The thermal conductivity and thermal decomposition temperature of GO/PU composite adhesive can be effectively improved by adding appropriate amount of GO.The tensile strength,thermal conductivity and thermal decomposition temperature of polyurethane adhesive reached the maximum when GO content was 1.5 wt%.The novel GO-modified polyurethane adhesive exhibited good insulation property.The development of GO/PU thermal conductive adhesive will provide a facile method for effectively solving the “trade-off” problem between low filling and high thermal conductivity.

Electrical Properties of Semi-insulating GaAs Grown from the Melt Under Microgravity Conditions

A technologically important undoped semi-insulating(SI)GaAs single crystal was successfully grown in the Chinese recoverable satellite as far as we know for the first time by using a similar growth configuration described previously.The experimental results proved that the space SI GaAs crystals have a lower density of defects and defect-impurity complexes as well as a better uniformity.

Preparation of Nanoporous Thermal Insulating Materials and Their Application as Ladle Linings

The nanoporous thermal insulating material was prepared by using fumed silica,SiC powder and glass fiber as starting materials,the appropriate thickness of the nanoporous thermal insulating material lined in ladle was discussed by the simulation method,and the effect of its application as ladle lining was investigated.The results show that the thermal conductivity of the nanoporous thermal insulating material prepared in composition of fumed silica： SiC powder： glass fiber =75： 20：5 （in mass） is 0.023 W · m^-1 · K^-1 at 1 000 ℃,the appropriate thickness of the nanoporous thermal insulating material lined in ladle is ≤ 5 mm and the average temperature of the ladle outside surface when lined with the nanoporous thermal insulating material is 95 ℃ lower than that with the ordinary thermal insulating material.

Predicted novel insulating electride compound between alkali metals lithium and sodium under high pressure

The application of high pressure can fundamentally modify the crystalline and electronic structures of elements as well as their chemical reactivity, which could lead to the formation of novel materials. Here, we explore the reactivity of lithium with sodium under high pressure, using a swarm structure searching techniques combined with first-principles calculations, which identify a thermodynamically stable Li–Na compound adopting an orthorhombic oP8 phase at pressure above 355 GPa. The formation of Li–Na may be a consequence of strong concentration of electrons transfering from the lithium and the sodium atoms into the interstitial sites, which also leads to open a relatively wide band gap for Li NaoP8. This is substantially different from atoms sharing or exchanging electrons in common compounds and alloys. In addition, lattice-dynamic calculations indicate that Li Na-oP8 remains dynamically stable when pressure decompresses down to 70 GPa.

Microclimatic Experimentation Applied to Insulating Horizontal Coverage in Mexicali, Mexico

The thermal response of hedges alters the urban climate, resulting in energy and comfort affectations that impact city dwellers, so the aim of this study is to analyze the energy fluxes of urban horizontal coverage, especially expanded polystyrene waterproofed with elastomeric paint in the city of Mexicali, Baja California, located northwest of Mexico. The experiment was realized on summer of 2011 and 2012 by using four components radiometric sensor, eddy covariance equipment, which was possible to analyze the behavior and intensities of heat fluxes using the model Q＊ = QE ＋ QG ＋ QH ＋ QF ＋ QD. The results show that in both campaigns the sensible heat flux exceeds the net radiation, in 2011 the net radiation was 31.41 W/mE and sensible heat flux of 74.9 W/m2, in 2012 resulted 43.46 W/m2 and 87.32 W/mE, respectively. This additional heat flux is attributed to the thermal influence of the air conditioning units, which changes the energy balance model to Q＊ = QH ＋ QF ＋ QD. With the results arise the need for experimentation on a larger scale in which it is possible to model the flow in housing development. The knowledge of the energy balance model will help to propose materials that minimize the thermal impact to the city of Mexicali.

The Effects of Firing Temperatures on the Performance of Insulating Firebricks Containing Different Proportions of Alumina and Sawdust

This work studied the effects of firing temperatures on the refractory properties of insulating firebricks produced from a blend of hydrometallurgically purified clay, high alumina cement and sawdust. Twenty grams out of a bulk (1000 Kg) of clay obtained from Ipetumodu in Nigeria was analyzed for size range, consequent upon which the remaining bulk was sieved to 100 μm, being the average size. The bulk was there after leached under a predetermined condition (1.6 mol/dm3 of oxalic acid at 70oC for 150 min and 200 rev/min agitation speed) and cylindrical samples (5 cm diameter by 5 cm high) containing different quantities of high alumina cement (5% - 20%) and sawdust (1% - 5%) were prepared, dried at 110oC and subsequently fired at 900oC, 1100oC, 1300oC and 1500oC, at the rate of 4oC/min and soaked for 2 hrs. These samples were subjected to different refractory tests (permanent linear change, modulus of rupture, bulk density, cold crushing strength and apparent porosity). Even though samples containing more than 20% alumina crumbled at elevated temperatures, it was still observed that the bricks performed to expectations at lower alumina contents, even at 1500oC. The sample containing 3% sawdust and 10% alumina cement however, gave the desired requirement for preparing good insulating firebricks with reliable phase integrity, as revealed by scanning electron microscopy (SEM).

Development of a New Bio-Based Insulating Fluid from <i>Jatropha curcas</i>Oil for Power Transformers

The present work aims to develop a new vegetable insulating fluid for power transformers based on Jatropha curcas oil. Besides its technical benefits, Jatropha curcas oil has a socio-economic role by promoting income to rural families, contributing to the countryside development and avoiding rural exodus. Thus, the entire transformer oil production (extraction, processing, characterization and accelerated aging) was covered and a new process was developed. For oil extraction, the most suitable process was the solvent extraction (5 mL of hexane per gram of crushed non-peeled seeds during 30 minutes) with an oil yield of 32%. In raw oil processing stage, the degumming, with 0.4 g of phosphoric acid per 100 g of oil, at 70°C, was used to remove phosphatides. Then, free fatty acids were 96% neutralized with a sodium hydroxide solution (0.5% w/w) at room temperature. For the oil clarification, the combination of 5% w/woil of activated carbon and 1% w/woil of MgO resulted in a bright, odorless and clear oil with an acid number of 0.04 mgKOH·g﹣1. The oil drying in a vacuum rotary evaporator, at 70°C, for 2 hours reduced the water content to 177 ppm. The processed oil was characterized following ASTM D6871 methods. This oil presented higher dielectric breakdown voltage (55 kV) than commercial transformer fluids (BIOTEMP?, EnvirotempFR3?, and Bivolt?), which increases transformer safety, capacity and lifetime. In addition, the processed oil has a lower viscosity than BIOTEMP? fluid, which can enhance the heat dissipation efficiency in the transformer. Moreover, the processed oil flash and fire points of 310°C and >340°C, respectively, confirm the great security of vegetable insulating fluids. The analyzed properties of the processed oil fulfill all the ASTM D6871, ABNT NBR 15422 and IEC 62770 specifications. Therefore, Jatropha curcas oil is a potential substitute formineral insulating fluids.

Magneto-Transport Properties of Insulating Bulk States in Bi(111) Films

Magneto-transport properties of insulating bulk states in Bi（111） films are systematically investigated under the parallel field （BⅡ）. We find that the magnetotransport of the Bll field is a more powerful tool to distinguish the bulk states and the surface states. A large magnetoresistance （MR） up to 20% in the BⅡ field is induced by the insulating bulk states for the suppression of the backward scattering. With the increasing thickness, a positive MR（BⅡ） from magnetic induced boundary scattering appears in the semimetal films. As the thickness is reduced to 1Ohm, the positive MR（BⅡ） is induced by weak anti-localization from the surface states.