Precise determination of bromine in PP resin pellet by instrumental neutron activation analysis using internal standardization

Instrumental neutron activation analysis with the internal standardization was applied to the precise determination of Br in polypropylene resin of candidate certified reference material. The known amount of ¹⁹⁷Au was used as an internal standard to compensate for neutron flux inhomogeneity, to improve the γ ray measurement uncertainty and the linearity of the calibration curves. The reliability of the proposed method validated using analytical results of BCR-681. The analytical result of Br in the sample was consistent with that obtained by ID-ICPMS. The relative expanded uncertainty (k = 2) was 1.5 %, and it was equivalent to that of ID-ICPMS.     

Effect of preparation process of microfibrillated cellulose-reinforced polypropylene upon dispersion and mechanical properties

Microfibrillated cellulose (MFC)-reinforced polypropylene (PP) was prepared via two engineering approaches: disintegration of the pulp by a bead mill followed by a melt-compounding process with PP (B-MFC-reinforced PP); and disintegration of the pulp mixed with PP by a twin screw extruder followed by a melt-compounding process (T-MFC-reinforced PP). The effects that the engineering process and the microfibrillation of the pulp had upon the dispersion and mechanical properties were investigated through tensile tests, rheological analysis and X-ray computed tomography. The bead-milling method enabled a uniform microfibrillation of the pulp to under 100 nm, which corresponded to a surface area of 133–146 m²/g for the pulp, found by the Brunauer–Emmett–Teller (BET) analysis. The T-MFC-reinforced PP with 30 wt% MFC content exhibited a tensile modulus of 5.3 GPa and a strength of 85 MPa, whereas the B-MFC-reinforced PP composites with the same content of MFC exhibited values of 4.1 GPa and 59.6 MPa, respectively. Rheological analysis revealed that the complex viscosity and storage modulus at 170 °C of T-MFC-reinforced PP with 30 wt% MFC content are 5–7 and 5–8 times higher than that of B-MFC-reinforced PP, respectively. This indicated that T-MFC was more dispersed in the PP than B-MFC. Therefore, T-MFC produced a more rigid interconnected network in the matrix during the melting state than B-MFC.     

Multi-period resource allocation for estimating project costs in competitive bidding

Central European Journal of Operations Research - In competitive bidding for project contracts, contractors estimate the cost of completing a project and then determine the bid price. Accordingly,...     

Sequential injection immunoassay for environmental measurements

Sequential injection immunoassay systems for environmental measurements based on the selective immunoreaction between antigen and antibody were described. A sequential injection analysis (SIA) technique is suitable to be applied for the procedure of enzyme-linked immunosorbent assay (ELISA), because the washing and the addition of reagent solutions can be automated by using a computer-controlled syringe pump and switching valve. We selected vitellogenin (Vg), which is a biomarker for evaluating environmental risk caused by endocrine-disrupting chemicals in the hydrosphere, and linear alkylbenzene sulfonates (LAS) and alkylphenol polyethoxylates (APEO), which are versatile surfactants, as target analytes in the flow immunoassay systems. For Vg monitoring, SIA systems based on spectrophotometric, chemiluminescence, and electrochemical determinations were constructed. On the other hand, chemiluminescence determination was applied to the detection of LAS and APEO. For APEO, an SIA system combined with surface plasmon resonance (SPR) sensor was also developed. These new sequential injection immunoassay systems are expected to be useful systems for environmental analysis.     

Perylene bisimide as a versatile fluorescent tool for environmental and biological analysis: a review

Perylene bisimide (PBI) is a fluorescent dye which has strong emission and high photostability. Although PBI has been widely used for industrial materials, the application of PBI in analytical fields was limited mainly due to its high hydrophobicity. In recent years, however, unique and useful analytical methods based on PBI platform are being successfully developed by utilizing the characteristic features of this compound including its high hydrophobicity. In this article, the recent trend of environmental and biological analysis using PBI is reviewed.     

Theoretical study on singlet oxygen adsorption onto surface of graphene-like aromatic hydrocarbon molecules

Recently, graphene sheet is one of interesting systems to realize novel electronic properties. Especially, interaction between graphene and adsorbed oxygen molecule is very important to control electronic condition. In this paper, we employed some aromatic hydrocarbons as simple systems of graphene sheet and ab initio MO calculations were carried out to investigate inter-molecular interaction. It is found that not triplet but singlet O₂ molecule have potential of chemisorption onto graphene surface. From the calculated potential energy surface (PES) for distance between benzene and O₂ molecules, meta-stable structure is found at about 1.5 Å with potential barrier. In the optimized structure of its meta-stable state, structural strain can be relaxed through bending of planer benzene ring. Its energy is estimated at 70.10 kcal/mol for benzene. We also estimated the strain effects for naphthalene and pyrene molecules as larger case of graphene and they were 80.85 and 72.45 kcal/mol, respectively.     

Potential energy curve for ring-opening reactions: comparison between broken-symmetry and multireference coupled cluster methods

The spin-unrestricted Hartree-Fock (UHF)-based coupled cluster singles and doubles (UHF-CCSD) and Mukherjee's state-specific multireference CCSD (MkCCSD) methods are applied to four ring-opening reactions. The spin-restricted Hartree-Fock (RHF)-based CCSD (RHF-CCSD) calculations are also performed for comparison. In the case of the UHF-CCSD method, an approximate spin-projection (AP) method is applied to the broken-symmetry (BS) singlet solution to remove the spin contamination effect. For potential energy curves (PECs) of all reactions presented in this study, the results of RHF-CCSD and UHF-CCSD are substantially different from those of MkCCSD, while the results after the AP method (AP-UCCSD) reproduce the MkCCSD results well. It strongly suggests that the spin contamination effect should be removed by the AP correction even at the UHF-CCSD level to predict reliable energetics of these reactions.     

Generation of nitrile oxides from oximes using t-BuOI and their cycloaddition

tert-Butyl hypoiodite (t-BuOI) was found to be a powerful reagent for the cycloaddition of oximes and alkenes/alkynes, leading to the formation of a variety of isoxazolines or isoxazoles under mild conditions.     

Silver-catalyzed regioselective carbomagnesiation of alkynes with alkyl halides and Grignard reagents

A silver-catalyzed carbomagnesiation of alkynes with alkyl halides and Grignard reagents afforded alkenyl Grignard reagents regioselectively, where the alkyl group of the alkyl halide, but not that of the Grignard reagent, was introduced into the alkyne. Application to δ-haloalkylacetylenes yielded cyclopentanes or a tetrahydrofuran containing an exo-methylene substituent via 5-exo-dig cyclization.     

Localization of the Grover Walks on Spidernets and Free Meixner Laws

In the first part, we have constructed several families of interacting wedge-local nets of von Neumann algebras. In particular, we discovered a family of models based on the endomorphisms of the U(1)-current algebra ${\mathcal{A} ^{(0)}}$ of Longo-Witten. In this second part, we further investigate endomorphisms and interacting models. The key ingredient is the free massless fermionic net, which contains the U(1)-current net as the fixed point subnet with respect to the U(1) gauge action. Through the restriction to the subnet, we construct a new family of Longo-Witten endomorphisms on ${\mathcal{A} ^{(0)}}$ and accordingly interacting wedge-local nets in two-dimensional spacetime. The U(1)-current net admits the structure of particle numbers and the S-matrices of the models constructed here do mix the spaces with different particle numbers of the bosonic Fock space.