Chemometric modeling and prediction of trihalomethane formation in Barcelona's water works plant

Formation and occurrence of trihalomethanes (CHCl3, CHBr3, CHCl2Br, and CHBr2Cl) are investigated in water chlorination disinfection processes in the Barcelona's water works plant (WWP). Twenty-three WWP variables were measured and investigated for correlation with trihalomethane formation. Multivariate statistical methods including principal component analysis (PCA), multilinear regression (MLR), stepwise MLR (SWR), principal component regression (PCR) and partial least squares regression (PLSR) have been used and compared to model and predict the complex behavior observed for the measured trihalomethane concentrations. The results, obtained by PCA as well as the evaluation of the statistical significance of the coefficients in the linear regression vectors, revealed that the most important WWP variables for trihalomethane formation were: water temperature, total organic carbon, added chlorine concentrations, UV absorbance and turbidity at different sites of the WWP, as well as other variables like wells supply flow levels and carbon filters age. Overall, MLR and PLSR methods performed the best and gave similar good predictive properties. Best results were obtained for the total sum of trihalomethane concentrations, TTHM, with average modeling and prediction relative errors of 12% and 16%, respectively. Among the individual trihalomethanes, the concentrations of CHBr3 were the worst predicted ones with average modeling and prediction relative errors between 21-25% and 29-31%, respectively, followed by CHCl2Br with 23-26% and 25-27%. Better predictions were obtained for the concentrations of CHBr2Cl with relative modeling and prediction errors varying between 14-17% and 21%, and for the concentrations of CHCl3 with 21-24% and 23-25% errors, respectively.     

An Efficient Palladium‐NHC (NHC=N‐Heterocyclic Carbene) and Aryl Amination Pre‐Catalyst: [Pd(IPr*)(cinnamyl)Cl]

The well‐defined [Pd(IPr*)(cinnamyl)Cl] complex is reported as one of the best N‐heterocyclic carbene (NHC)‐based pre‐catalysts for the Buchwald–Hartwig amination reaction. This catalytic system displays high efficiency for the coupling of numerous (hetero)aryl chlorides, with a wide range of amines, at room temperature or at extremely low catalyst loading (as low as 0.025 mol%).     

Few electron limit of n-type metal oxide semiconductor single electron transistors

We report the electronic transport on n-type silicon single electron transistors (SETs) fabricated in complementary metal oxide semiconductor (CMOS) technology. The n-type metal oxide silicon SETs (n-MOSSETs) are built within a pre-industrial fully depleted silicon on insulator (FDSOI) technology with a silicon thickness down to 10 nm on 200 mm wafers. The nominal channel size of 20 × 20 nm(2) is obtained by employing electron beam lithography for active and gate level patterning. The Coulomb blockade stability diagram is precisely resolved at 4.2 K and it exhibits large addition energies of tens of meV. The confinement of the electrons in the quantum dot has been modeled by using a current spin density functional theory (CS-DFT) method. CMOS technology enables massive production of SETs for ultimate nanoelectronic and quantum variable based devices.     

Size effect of concrete samples on the kinetics of external sulfate attack

The external sulfate attack (ESA) of concrete is a disease related to expansive sulfate hydrate formation in a hardened cement matrix. The aim of this research is to study how the choice of a concrete sample size can impact on the kinetics of ESA, by exposing different types of specimen to constant immersion in a solution dosed with 5% Na₂SO₄⋅10H₂O. Monitoring involves mass, dynamic modulus and expansion measurements. It is concluded that 4 × 8 cm concrete cylinders (cored from 11 × 22 cm concrete cylinders) are more quickly damaged by ESA than usual sample types (11 × 22 cm concrete cylinders and 4 × 4 × 16 cm mortar prisms). For all sample types, damage is always limited to the periphery of the sample in the short run. The thickness of the damaged zone is in the region of the size of the largest aggregates. For 4 × 8 cm concrete cylinders, this periphery corresponds to the entire sample because the maximum aggregate size is of the order of the size of the specimen. In this situation, the percolating crack network resulting from swelling is assumed to dramatically damage the cement matrix and to give sulfate solution access to the whole sample. Hence, by using this original type of cored samples, the concrete resistance to sulfate attack can be studied under reliable conditions (concrete formulations and not mortar ones, good sensitivity to ultrasonic tests) and advantage can be taken of the increased kinetics of degradation.     

Causes, impact and control of overbreak in underground excavations

Drill and blast system is used in hard rock excavation due to its economics and adaptability to changing rock mass conditions. Common question during mining and tunneling operations is ‘whether overbreak has been caused by blasting practice or poor rock mass quality’. Critical evaluation of the factors influencing blast damage is required to address such questions.In order to understand the mysterious nature of blast damage prediction and control, the field work involved the small scale blasting of physical models and the assessment of blast damage during drifting operations. The damage was measured by the Half cast factor, percentage overbreak and the Blast damage index. The influence of rock mass features, explosive characteristics and blast design parameters on overbreak has been examined in this study. A new approach for the judicious design of perimeter hole pattern and charge concentration has been proposed. Implications of blast damage have also been outlined in this paper.     

High-pressure treatment of milk in industrial and pilot-scale equipments: effect of the treatment conditions on the protein distribution in different milk fractions

The effects of two different high-pressure (HP) equipments, operating at industrial- and pilot scales, and of the HP-release rate on the contents of non-sedimentable proteins and denatured whey proteins were investigated after treatments of skim milk—from 250 to 650 MPa. Non-sedimentable caseins and denatured whey proteins significantly increased with the pressure level. The industrial-scale equipment produced lower micellar disintegration than the pilot-scale equipment with similar degrees of whey protein denaturation. Ultracentrifugation supernatants obtained from skim milk at 100,000×g and 20 °C for 1 h were also HP-treated for comparative purposes, showing that, in skim milk, the presence of casein promoted the denaturation of whey proteins, although the extent of whey protein denaturation did not influence the release of casein to the soluble phase. Furthermore, most denatured whey proteins remained soluble after treatment in both equipments. In the pilot-scale equipment, the pressure-release rate influenced casein solubilization and whey protein denaturation.     

Novel thermal curing of cycloaliphatic resins by thiol–epoxy click process with several multifunctional thiols

Novel thermosets were prepared by the base‐catalysed reaction between a cycloaliphatic resin (ECC) and various thiol crosslinkers. 4‐(N,N‐Dimethylaminopyridine) (DMAP) was used as base catalyst for the thiol–epoxy reaction. A commercial tetrathiol (PETMP) and three different thiols synthesized by us, 6SH‐SQ, 3SH‐EU and 3SH‐ISO, were tested. 6SH‐SQ and 3SH‐EU were prepared from vinyl or allyl compounds from renewable resources such as squalene and eugenol, respectively. Thiol 3SH‐ISO was prepared starting from commercially available triallyl isocyanurate. A kinetic study of the mixtures was performed using differential scanning calorimetry. Stoichiometric ECC/thiol/DMAP formulations were cured at 120 °C for 1 h, at 150 °C for 1 h and post‐cured for 30 min at 200 °C. The materials were characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis and dynamic mechanical thermal analysis. The results revealed that the materials obtained from the synthesized thiols had higher thermal stability and glass transition temperatures than those obtained from the commercial PETMP. In addition, all the materials obtained exhibited very good transparency. This study proves the ability of multifunctional thiols to crosslink cycloaliphatic epoxy resins, leading to more flexible materials than those obtained by cationic homopolymerization of ECC or base‐catalysed ECC–anhydride copolymerization. © 2017 Society of Chemical Industry     

Multiarm star with poly(ethyleneimine) core and poly(ε-caprolactone) arms as modifiers of diglycidylether of bisphenol A thermosets cured by 1-methylimidazole

Well-defined multiarm star copolymers, with hyperbranched poly(ethyleneimine) (PEI) as the core and poly(ε-caprolactone) (PCL) arms with different degree of polymerization were synthesized by cationic ring-opening polymerization of ε-caprolactone from a hyperbranched poly(ethyleneimine) core and used to modify diglycidylether of bisphenol A formulations cured with 1-methylimidazole as anionic initiator. The curing process was studied by dynamic scanning calorimetry (DSC) and FTIR. By rheometry the complex viscosity of the multiarm stars synthesized and the influence of their addition to the reactive mixture was analyzed in detail. The resulting materials were characterized by thermal and mechanical tests. The addition of the multiarm star to the formulation led to homogeneous materials with a slightly toughened fracture in comparison to neat DGEBA thermosets without compromising thermal characteristics.