Computer-aided design of formulated products

Formulated products represent a particular class of complex chemical products, and their design is typically based on experience and extensive experimentation. Although still at an early stage, and despite that their potential is not fully accessed and not fully used by the industry, computer-aided design (CAD) methods and tools offer many possibilities in the design of formulated products. The CAD methodology based on computerized models enables the formulation chemists to speed up the design process, without completely replacing experiments.In this work, we summarize previous studies in the field and present important elements of the CAD framework, emphasizing estimation methods for key target properties, link to specifications, and finally, some case studies will illustrate how the CAD framework can be used in practice for formulated products.     

La单掺4H-SiC电子结构和光学性质的第一性原理研究

采用基于密度泛函理论的第一性原理计算方法，对未掺杂及La掺杂4H-SiC的电子结构和光学性质进行理论计算。计算结果表明，未掺杂4C-SiC其禁带宽度为2.257 eV。La掺杂后带隙宽度下降为1.1143eV，导带最低点为G点，价带最高点为F点，是P型间接半导体。掺杂La原子在价带的低能区间贡献比较大，而对价带的高能区和导带的贡献比较小。未掺杂4H-SiC在光子能量为6.25 eV时，出现一个介电峰，这是由于价带电子向导带电子跃迁产生。而La掺杂后，出现3个介电峰，分别对应的光子能量为0.47eV、2.67eV、6.21eV，前两个介电峰是由于价带电子向杂质能级跃迁产生，第三个介电峰是由于价带电子向导带电子跃迁产生。La掺杂后4H-SiC变成负介电半导体材料。未掺杂4h-SiC的静态介电常数为2.01，La掺杂的静态常数为12.01。     

A novel self activated K2XV2O7 (X = Mg and Zn) pyrovanadate green phosphor: Systematic characterization and time resolved photoluminescence

Novel self activated green phosphors; K₂ZnV₂O₇ (KZV) and K₂MgV₂O₇ (KMV) have been prepared and characterized in details. Both KZV and KMV were prepared by solid state reaction and systematically characterized by a number of techniques like X-ray diffraction (XRD), Fourier transformed Infrared (FTIR), Raman spectroscopy, Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), diffuse reflectance spectroscopy (DRS) and time resolved photoluminescence spectroscopy (TRPLS). XRD studies confirm tetragonal melilite type layered phase for both of them. The presence of pyrovanadate group in both is supported by FTIR and Raman spectroscopic investigations. Raman bands of KMV are blue shifted w.r.t to KZV which may be due to shorter bond lengths of MgO compared to ZnO and lower atomic weight of magnesium compared to zinc. DRS measurements indicated the optical band gap of KMV and KZV are 3.14 and 3.12 eV, respectively. Optical measurements on these samples show the emission of green color on ultra violet light irradiation. The origin of such emission is attributed to electronic transition (charge transfer) from filled 2p orbital of oxygen ion (O²⁻) to vacant 3d orbital of vanadium ion (V⁵⁺). In KZV there are dual emission band (PL1 and PL2) which are respectively attributed to ³T₂ → ¹A₁ and ³T₁ → ¹A₁transition, and the emission zone varies slightly compared to KMV. KZV emits bluish green (cool green) where KMV emits in yellowish green (warm green) region. This is indeed an important step towards realization of cost effective rare earth free luminescence material. It is also oberved that PL intensity of KZV is very high compared to KMV which is supported by the lifetime measurements.     

Morphology and properties of super-toughened bio-based poly(lactic acid)/poly(ethylene-co-vinyl acetate) blends by peroxide-induced dynamic vulcanization and interfacial compatibilization

Super-toughened poly(lactic acid) (PLA)/poly(ethylene-co-vinyl acetate) (EVA) blends were prepared via 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (AD) induced dynamic vulcanization and in situ interfacial compatibilization. The effects of AD on the morphology and properties of PLA/EVA blends were studied using a Brabender torque rheometer, gel content test, scanning electron microscopy (SEM), differential scanning calorimetry (DSC) thermogravimetric analysis (TGA) and mechanical properties test. The torque and gel content demonstrated that EVA and PLA was successfully vulcanized in the presence of free radicals obtained by the decomposition of the 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (AD). Additionally, the gel content results indicated that, compared with PLA, EVA is more aggressive with free radicals. The SEM revealed that a relatively uniform phase morphology and good interfacial compatibilization were achieved in the dynamically vulcanized PLA/EVA/AD blends. The interfacial reaction and compatibilization between the component polymers resulted in the formation of super-toughened PLA/EVA blended materials.     

A paper-based resonance energy transfer nucleic acid hybridization assay using upconversion nanoparticles as donors and quantum dots as acceptors

Monodisperse aqueous upconverting nanoparticles (UCNPs) were covalently immobilized on aldehyde modified cellulose paper via reduction amination to develop a luminescence resonance energy transfer (LRET)-based nucleic acid hybridization assay. This first account of covalent immobilization of UCNPs on paper for a bioassay reports an optically responsive method that is sensitive, reproducible and robust. The immobilized UCNPs were decorated with oligonucleotide probes to capture HPRT1 housekeeping gene fragments, which in turn brought reporter conjugated quantum dots (QDs) in close proximity to the UCNPs for LRET. This sandwich assay could detect unlabeled oligonucleotide target, and had a limit of detection of 13 fmol and a dynamic range spanning nearly 3 orders of magnitude. The use of QDs, which are excellent LRET acceptors, demonstrated improved sensitivity, limit of detection, dynamic range and selectivity compared to similar assays that have used molecular fluorophores as acceptors. The selectivity of the assay was attributed to the decoration of the QDs with polyethylene glycol to eliminate non-specific adsorption. The kinetics of hybridization were determined to be diffusion limited and full signal development occurred within 3 min.     

Fluorescence properties of riboflavin-functionalized mesoporous silica SBA-15 and riboflavin solutions in presence of different metal and organic cations

Riboflavin was covalently linked to mesoporous SBA-15 silica surface via grafting technique. Then fluorescence properties of the system obtained were analyzed in the presence of several metal and organic cations. Both quenching and strengthening of fluorescence as well as significant changes in the maximum fluorescence wavelength were observed. The results were compared with absorption and fluorescence data obtained for riboflavin water solutions.     

Theoretical study of photoluminescence spectroscopy of strong exciton-polariton coupling in dielectric nanodisks with anapole states

Semiconductor nanoparticles and nanostructures in the strong coupling regime exhibit an intriguing energy scale in the optical frequencies, which is specified by the Rabi splitting between the upper and lower exciton-polariton states. Technically, exciton-polaritons are part-light, part-matter quasiparticles that arise from the strong interaction of excitonic substances and photonic platforms. In this work, using full-wave numerical and theoretical studies, we showed the emergence of strong light-matter coupling between the nonradiating anapole states from an individual semiconductor nanodisk coupled to a J-aggregate fluorescent dye molecule resonating in the visible spectrum. By demonstrating the physical mechanism behind the observed energy splitting for various Lorentzian linewidth of excitonic material, we theoretically confirmed the obtained spectral responses by conducting photoluminescence spectroscopy analysis. The coupling of anapole resonances in semiconductor nanoparticles with excitonic levels can propose interesting possibilities for the control of directional light scattering in the strong coupling limit, and the dynamic tuning of deep-subwavelength light-matter coupled states by external stimuli.     

Ce掺杂6H-SiC电子结构和光学性质的第一性原理研究

采用基于密度泛函理论的第一性原理计算方法,对未掺杂及Ce掺杂6H-SiC的电子结构和光学性质进行理论计算.计算结果表明,未掺杂6H-SiC是间接带隙半导体,其禁带宽度为2.045 eV,掺杂Ce元素,带隙宽度下降为0.812 eV.未掺杂6H-SiC在价带的低能区,Si-3s、C-2s电子轨道对态密度的贡献较大,在价带的高能区,主要是由Si-3p、Si-3s、C-2p态组成.掺杂后Ce原子的4f轨道主要贡献在导带部分,掺杂后电导率提高.未掺杂时,只有一个介电峰,是价带电子跃迁到导带电子所致,掺杂后有两个介电峰,第一个介电峰是由于导带电子跃迁到Ce原子4f轨道上产生,第二个峰是价带电子向导带电子跃迁产生.未掺杂6H-SiC,在能量为10.31 eV处吸收系数达到最大值,掺杂后在能量为6.57 eV处,吸收系数达到最大值.     

Curing behavior and properties of high biosourced epoxy resin blends based on a triepoxy monomer and a tricarboxylic acid hardener from 10-undecenoic acid

Renewable propane-1,2,3-triyl tris(9-(oxiran-2-yl) nonanoate) (EGU, 100 wt% biogenic) and a tricarboxylic acid triglyceride (CGTU) hardener (85.7 wt% biogenic) were synthesized from 10-undecenoic acid (10-UDA) and used to produce epoxy resins with 52–92 wt% biobased carbon. CGTU was prepared by thermally activated thiol-ene coupling of thioglycolic acid onto propane-1,2,3-triyl tris(undec-10-enoate), (GUD) in the absence of solvent. The characterized CGTU was used as a green hardener of blends based on EGU and a conventional bisphenol A-based epoxy pre-polymer (DGEBA) at various mass percentages (0–100 wt%) with an stoichiometric epoxy/acid equivalent ratio. Calorimetric studies revealed higher peak temperature, lower reaction heats, and longer gelation times in resins with high EGU proportion, evidencing the lower reactivity of aliphatic EGU compared with aromatic DGEBA. Cured resins were yellowish transparent rubber-like materials with glass transition temperatures (Tg) varying from −14 °C to −42 °C and tensile strength in the range of 1750 kPa–790 kPa, for 0 and 100 wt % EGU, respectively. The soluble fraction of all resins was less than 4.3%, reflecting a high level of crosslinking. Thermosets with high biobased content showed both UV-light protection and visible light transparency.