- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Interactions between CdTe quantum dots and plasma proteins: kinetics, thermodynamics and molecular structure changes
摘要： Environmental particulate matter, especially ultrafine particles (< 100 nm in diameter), can damage the endothelium and favor cardiovascular disease in the general population. With the wide application of nanomaterials, exposure to nanoscale particles (nanoparticles) in the environment is increasing. Systematic study of the interaction of nanoparticles with plasma proteins is critically important for understanding the cardiovascular toxicity of nanomaterials. We combined kinetics and thermodynamics information from surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC) and conformational data from fluorescence spectroscopy and circular dichroism (CD) to explore the binding mechanism between cadmium telluride quantum dots (CdTe QDs) and plasma proteins. Special attention was paid to the interaction between CdTe QDs and coagulation-related proteins and the effects of CdTe QDs on protein conformation. The results showed that the binding affinities of CdTe QDs and plasma proteins depend on the nature of the protein and follow the order of fibrinogen (FIB) > plasminogen (PLG) > thrombin (TM) > metallothionein-II (MT-II) > human serum albumin (HSA). The interaction was primarily attributed to hydrophobic forces and the spontaneity of the occurrence of the interaction, and the protein secondary structures of FIB and PLG were changed significantly. The information gained in this study might shed light on the potential toxicity of QDs to the cardiovascular system.
关键词： plasma proteins,circular dichroism,isothermal titration calorimetry,CdTe quantum dots,surface plasmon resonance
更新于2025-09-23 15:19:57
-
Thermophysical Properties of Silicon-Carbide-Based Ceramic Composite Materials Obtained by Spark Plasma Sintering (SPS)
摘要： The factors influencing the thermal conductivity of SiC-based ceramic composite materials obtained by the spark plasma sintering technology with relative density 99% and B4C, AlN, Si3N4, Y2O3, Al2O3, and HfB2 as additives are examined. The thermophysical properties were determined in the temperature range 20 – 1300°C: specific heat, thermal diffusivity, and thermal conductivity of composites. The thermal diffusivity and specific heat were measured by the laser-spark method. The measurements of specific heat are supplemented by measurements performed with a DSC and adiabatic calorimeter. The thermal conductivity is calculated using data on the thermal diffusivity, specific heat, and density.
关键词： laser flash method,specific heat,adiabatic calorimeter,thermal conductivity,ceramic composite materials,thermal diffusivity,thermophysical properties,differential scanning calorimetry (DSC)
更新于2025-09-19 17:15:36
-
Effects of the biaxial orientation on the mechanical and optical properties and shrinkage of polyamide 6-66-montmorillonite-nanosilica nanocomposite films
摘要： Polyamide 6–66 (PA6-66)–montmorillonite (MMT)–nanosilica (NS) nanocomposite ?lms were fabricated through a cast ?lm process and then biaxially stretched on a laboratory stretcher. Uniaxial or biaxial stretching induced the elongated conformation of MMT and NS. The b axis of the α crystals and the amorphous phase were revealed to align along the machine direction (MD) after stretching, with the uniaxial orientation playing a more signi?cant role. Furthermore, the crystallinity of PA6-66 stretching increased with the stretching ratio. Uniaxial stretching gave rise to a signi?cantly enhanced tensile strength along the MD, whereas it slightly decreased the mechanical properties along the transverse direction (TD). In contrast, the ?lms subjected to biaxial stretching exhibited more balanced mechanical properties. Uniaxial and biaxial stretching led to decreased transmittance and increased haze in the PA6-66–MMT–NS ?lms; this could have been due to the elongated nanostructure of the two nano?llers, which inhibited the transmission and facilitated the scattering of visible light. The thermal shrinkage of the ?lms increased with increasing stretching ratio, and the biaxially oriented ?lms presented nearly equal shrinkage in the MD and TD. The addition of nano?llers decreased the shrinkage attributed to the mobility inhibition of the polymer chains during heating. ? 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47504.
关键词： packaging,nanostructured polymers,?lms,differential scanning calorimetry (DSC),X-ray
更新于2025-09-19 17:15:36
-
[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Measurement Uncertainties in the Calibration of Multi-Junction Solar Cells using Different Sun Simulators and Reference Devices
摘要： The CMS lead tungstate (PbWO4) electromagnetic calorimeter (ECAL) has successfully achieved its first goal: the discovery of the Higgs boson in 2012. However, longevity studies show that part of the PbWO4 ECAL will not maintain the required performance due to radiation damage incurred at the HL-LHC. The forward region of the detector will suffer the most from radiation damage, and the ECAL Endcaps (EE) will need to be replaced. A scintillator-based option for the EE replacement, Shashlik EE, is presented in the paper. The Shashlik EE is a sampling calorimeter. Tungsten absorber plates are interleaved with scintillator plates (LYSO or CeF3), with quartz and wavelength-shifting (WLS) capillaries optically coupled to the scintillator plates for light output. The Shashlik EE maintains an excellent energy resolution, but compared to the current PbWO4 EE, it is at least five times greater in radiation hardness and has a module size four times smaller allowing four times higher granularity laterally for pileup mitigation and particle identification. Irradiation tests and beam tests results have confirmed the high performance of the Shashlik EE.
关键词： Calorimetry,solid scintillation detectors,photondetectors
更新于2025-09-19 17:13:59
-
Supercooled Liquid β-Diketones with Mechanoresponsive Emission
摘要： Shear-induced crystallization of dyes in the amorphous state is an effective strategy for generating higher energy emission after mechanical perturbation—a rare phenomenon in mechanoresponsive materials. Recently, we reported that a β-diketone with a 3,4,5-trimethoxy-substituted phenyl ring formed a stable supercooled liquid (SCL) phase after melting and cooling in air. To tune the lifetime of β-diketones in the SCL phase, a series of dyes with 3,4,5-trimethoxy-substituted phenyl rings were synthesized. Derivatives with naphthyl and phenyl rings were prepared in order to modulate crystallization through arene interactions. Additionally, dyes were substituted with alkoxy chains of varying length to promote crystallization through increased van der Waals interactions. Video screening in conjunction with differential scanning calorimetry and X-ray diffraction studies indicated that naphthyl-substituted derivatives exhibited increased melted state lifetimes and that increasing the alkoxy chain length can induce crystallization. Analysis of molecular packing of single crystals of PH, PC1, PC3, and PC5 revealed that the central para-substituted methoxy group of the trimethoxy-substituted ring was forced out of the molecular plane because of steric interactions with neighboring methoxy groups. The stabilities of the SCLs were generally correlated with the torsion angles of the para methoxy groups, where derivatives with smaller angles exhibited faster rates of crystallization. Mechanical perturbation of the SCL phases resulted in shear-induced crystallization of PH, PC1, PC3, and NC6 derivatives. In some cases, traditional mechanochromic luminescence with a crystalline-to-amorphous phase transition was also observed, which indicates that some trimethoxy-substituted β-diketones exhibit more than one type of mechanoresponsive luminescence.
关键词： van der Waals interactions,supercooled liquid (SCL),mechanochromic luminescence,mechanoresponsive materials,X-ray diffraction,β-diketone,Shear-induced crystallization,differential scanning calorimetry
更新于2025-09-19 17:13:59
-
Direct Determination of Total Hemispherical Emittance of Perovskite and Silicon Solar Cells
摘要： Because the performance and lifetime of a solar cell is sensitive to its operating temperature, an accurate knowledge of the total hemispherical emittance as a function of temperature is required. Granados et al. report a rapid transient calorimetry for the direct determination of total hemispherical emittance of perovskite and silicon solar cells over their operating temperature.
关键词： total hemispherical emittance,perovskite solar cells,silicon solar cells,transient calorimetry,radiative heat transfer
更新于2025-09-16 10:30:52
-
Transformation of the dermal collagen framework under laser heating
摘要： The aim of this study was to compare between the changes undergone by the framework when dermal collagen heated by IR laser radiation and by traditional means and to reveal the specific features of the dermal matrix modification under moderate IR laser irradiation. Rabbit skin specimens were heated to 50°C, 55°C, 60°C and 65°C in a calorimeter furnace and with a 1.68-μm fiber Raman laser. The proportion of the degraded collagen macromolecules was determined by differential scanning calorimetry. Changes in the architectonics of the collagen framework were revealed by using standard, phase-contrast, polarization optical and scanning electron microscopy techniques. The collagen denaturation and dermal matrix amorphization temperature in the case of laser heating proved to be lower by 10°C than that for heating in the calorimeter furnace. The IR laser treatment of the skin was found to cause a specific low-temperature (45°C-50°C) transformation of its collagen framework, with some collagen macromolecules remaining intact. The transformation reduces to the splitting of collagen bundles and distortion of the course of collagen fibers. The denaturation of collagen macromolecules in the case of traditional heating takes its course in a threshold manner, so that their pre-denaturation morphological changes are insignificant.
关键词： calorimetry,collagen transformation,skin,laser heating
更新于2025-09-11 14:15:04
-
Synthesis and electro-optic properties of novel Y-type polyimide containing nitrothiazolylazodioxyphenyl group
摘要： New Y-type polyimide (5) containing nitrothiazolylazodioxyphenyl groups as nonlinear optical (NLO) chromophores, which are components of the polymer backbone, was prepared and characterized. Polyimide 5 is soluble in common organic solvents such as N,N-dimethylformamide and dimethylsulfoxide. Polyimide 5 shows a thermal stability up to 300 °C in thermogravimetric analysis with glass-transition temperature (Tg) obtained from differential scanning calorimetry near 130 °C. The second harmonic generation (SHG) coefficient (d33) of poled polymer film at the 1064 nm fundamental wavelength is around 2.32 pm/V. The dipole alignment of polymer 5 exhibits a thermal stability even at 5 °C higher than Tg, and there is no SHG decay below 135 °C due to the partial main-chain character of polymer structure, which is acceptable for NLO device applications.
关键词： thermogravimetric analysis (TGA),NLO,dipole alignment,SHG coefficient,differential scanning calorimetry (DSC),polyimide
更新于2025-09-11 14:15:04
-
Solubility and H-bonding of poly(vinylidene fluoride) copolymers in carbonyl liquids: Experiment and molecular simulation
摘要： H-bond formation among fluoropolymers and carbonyl solvents was studied by microcalorimetry and quantum chemistry simulation. Typically, fluorine atoms in organic molecules depress their ability to molecular interactions with solvents. Meanwhile, it is not the case if fluoropolymer is dissolved in carbonyl solvent. Among other organic solvents carbonyl-containing liquids are characterized by very large exothermic effects of dissolution of vinylidene fluoride copolymers which are typical for the systems with electron-donor-acceptor complexes. The enthalpy of mixing in the entire concentration range was determined for P(VDF-co-HFP) and P(VDF-co-CTFE) solutions in ethyl acetate and Flory-Huggins parameter was evaluated. It was ?1.31, which means very strong interaction among solvent and vinylidene fluoride monomer units. This interaction was modeled by quantum chemistry semi-empirical AM1, PM3, PM5 and density functional B88-PW91, B88-LYP, D-VWN calculations for the complexes between acetone or ethyl acetate and vinylidene fluoride tetramer. The heat of formation of the complex from its components was found around ?18 kJ/mol. The binding site of the complex was a macrocyclic structure which comprised H-bonds between carbonyl and methylene hydrogens of vinylidene fluoride backbone, and weaker H-bonds between fluorine atoms and methyl hydrogen. The analysis of molecular orbitals of the complex reveals extended electron delocalization across the binding center.
关键词： Calorimetry,H-bonding,Computer modeling,Solubility of vinylidene fluoride copolymers
更新于2025-09-10 09:29:36
-
β-Phase Crystallization of Poly(vinylidene fluoride) in Poly(vinylidene fluoride)/Poly(ethyl methacrylate) Blends
摘要： The nature of the crystalline phase of poly(vinylidene fluoride) (PVDF) in compatible blends with poly(ethyl methacrylate) (PEMA) was investigated by using X-ray diffraction (XRD), infrared microscopy (IR) and differential scanning calorimetry (DSC). The β phase of PVDF was observed after quenching from the melt and further annealing above the glass transition temperature over a composition range. The PVDF/PEMA blend with weight ratio of 3:2 has formed higher content of PVDF β crystals than others. By taking advantage of fast cooling rate of ultrafast differential scanning calorimeter (UFDSC), the quenching process of blends was modeled and tested simultaneously, and the melting behavior of β crystals in all blends was investigated. Three types of crystallization behavior of β phase PVDF in blends were found after quenching-annealing at different temperatures.
关键词： PVDF/PEMA blend,Ultra-fast scanning calorimetry,Mesophase,β-Crystal of PVDF
更新于2025-09-10 09:29:36