An investigation of sensible heat fluxes at a green roof in a laboratory setup

During the last few years, several models have been proposed for the calculation of green roof thermal behavior, but the validation studies of such models are lacking a comprehensive set of highly accurate data. In this study, an experimental laboratory setup was used to create different environmental conditions and to measure sensible heat fluxes to/from a vegetated roof assembly. This experimental setup has been successfully used for different wind velocities (0–3 m/s) to create free and forced convection conditions around green roof tested samples. Furthermore, our study proposed a “basic model” for calculations of the convective heat transfer at green roof assemblies, which is a modified version of the Newton’s cooling law, calibrated and then validated with different sets of data. For forced convection flow regimes, the proposed “basic model” resulted in RMSE (Root Mean Square Error) of 11 W/m² and R² value of 0.81. Similarly, the model provided RMSE of 6.6 W/m² and R² of 0.90 for sensible heat fluxes with free convection conditions. In the future, this model will be used in on-site experimental studies to understand its performance under wind conditions that exhibit a much wider range than the studied velocity range near the leaf canopy.     

Photo‐Induced Functionalization of Spherical and Planar Surfaces via Caged Thioaldehyde End‐Functional Polymers

The synthesis and application of a novel reversible addition‐fragmentation chain transfer (RAFT) agent carrying a photocaged thioaldehyde moiety is described (λ_max = 355 nm). RAFT polymerization of styrene, dimethylacrylamide and a glycomonomer is evidenced (3600 g mol^?1 ≤ M_n ≤ 15 000 g mol^?1; 1.07 ≤ ? ≤ 1.20) with excellent end‐group fidelity. The photogenerated thioaldehyde on the chain ends can undergo hetero Diels–Alder reactions with dienes as well as reactions with nucleophiles. The terminal photoreactive polymers are photografted to porous diene‐reactive polymeric microspheres. The grafted particles are in‐depth characterized via scanning electron microscopy, elemental analysis, X‐ray photoelectron spectroscopy, and high resolution FT‐IR microscopy, leading to a qualitative as well as quantitative image of the core–shell objects. Grafting densities up to 0.10 molecules nm^?2 are reached. The versatility of the thioaldehyde ligation is evidenced by spatially resolved grafting of polystyrene onto nucleophilic groups present in poly (dopamine) (PDA)‐coated glass slides and silicon wafers via two‐photon direct laser writing (DLW) imaged by ToF‐SIMS. The combination of thioaldehyde ligation, RAFT polymerization, and DLW allows for the spatially resolved grafting of a vast range of polymers onto various substrates in any desired pattern with sub‐micrometer resolution.     

Preparation of antistatic and biodegradable packaging of PLA/PHBV blend-based glassy carbon and graphene nanoplatelets composites

Glassy carbon (GC) and graphene nanoplatelets (GNP) were used as fillers for the preparation of antistatic and biodegradable composites based on poly (lactic acid)/poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PLA/PHBV) blend. In this work, PLA/PHBV (80/20) blends with the addition of different GC contents (0.1, 0.3, and 0.5 wt%) were prepared by melt mixing using a twin-screw extruder, and specimens were injection molded. Furthermore, hybrid composites were prepared with the addition of 5 wt% of GNP and different GC contents (0.1, 0.3, and 0.5 wt%) using the same processing. The effect of the addition of GC and GNP on the mechanical, electrical, and electromagnetic properties and its effect on the biodegradability of the PLA/PHVB blend was evaluated. The simultaneous addition of GC (0.3 and 0.5 wt%) and GNP (5 wt%) significantly increases the elastic modulus and decreases the electrical resistivity, becoming suitable for electrostatic discharge protection packaging applications. The hybrid composite GC0.5/GNP5 reached a maximum value of total attenuation (4.5 dB), which corresponds to 60% EMI shielding. The degree of crystallinity affects biodegradability more than the type or presence of carbon material. After 110 days of anaerobic biodegradation, the hybrid composite exhibited 10% biodegradability due to the high degree of crystallinity that hinders the biodegradability process. The hybrid composites with the addition of GC and GNP are very promising for use in antistatic packaging.     

Combining parasitoids and plant resistance for the control of the bruchid Acanthoscelides obtectus in stored beans

Acanthoscelides obtectus (Say) and Zabrotes subfasciatus (Boheman) are the main bruchid pests of stored beans in widespread regions of Latin America and Africa. Host-plant resistance based on the protein arcelin is effective in reducing damage caused by Z. subfasciatus, but beans containing arcelin remain susceptible to A. obtectus. The compatibility of combining arcelin resistance with biological control by Dinarmus basalis (Rondani) was investigated in climatic chambers. Three arcelin containing bean varieties with high and intermediate resistance towards Z. subfasciatus (RAZ 36, RAZ 94 and RAZ 104) and an arcelin-free standard (Calima, susceptible to both bruchids) were investigated. Immature development of A. obtectus in arcelin-containing beans was prolonged by 15% as compared to the standard, allowing D. basalis to have access to suitable host stages for a longer period of time. Over a 20-week storage period, the combined use of resistant host plants and biological control agents yielded best results with the host-plant varieties RAZ 94 and RAZ 104. In both varieties, parasitoids managed to keep bruchid damage below 1% as compared to 4.7% in the arcelin-free standard, and bruchids were eradicated in 80% of the replicates. Control levels in RAZ 36, the bean variety with the highest resistance to Z. subfasciatus, were not greater than the standard. Our results show that the combination of certain arcelin-enriched bean varieties with the parasitoid D. basalis is favourable for suppressing damage by A. obtectus.     

Adsorption and desorption dynamics of associative polymers onto particulates of titanium dioxide,alumina and quartz

The authors have been investigating the adsorption and desorption dynamics of nonionic water soluble polymers on inorganic particles. The influence of the nature of polymers with and without associating hydrophobic end groups, the nature of adsorbents [TiO₂, Al₂O₃ (neutral, acid and basic), and SiO₂], polymer concentrations, linear velocity of fluids, and mutual diffusion of polymer molecules on the patterns of adsorption and desorption distribution of polymer concentrations are shown. The model polymer is a nonionic polyurethane polymer based on ethylene oxide. The polymer's structure is R-O-(DI-PEO)₆-DI-O-R (R is C₁₆H₃₃, DI is isophorone diisocyanate, and PEO is CARBOWAX^TM with a molecular weight of 8200). The phenomenological models of association and dissociation kinetics of associative polymers are suggested. The half-lives of clusters into adsorption and desorption layers are estimated. It is shown that heats of desorption of associative polymers are dependent essentially on heats of dissociation of clusters.     

Exhaust emissions and electric energy generation in a stationary engine using blends of diesel and soybean biodiesel

The present work describes an experimental investigation concerning the electric energy generation using blends of diesel and soybean biodiesel. The soybean biodiesel was produced by a transesterification process of the soybean oil using methanol in the presence of a catalyst (KOH). The properties (density, flash point, viscosity, pour point, cetane index, copper strip corrosion, conradson carbon residue and ash content) of the diesel and soybean biodiesel were determined. The exhaust emissions of gases (CO, CO₂,C_xH_y,O₂, NO, NO_x and SO₂) were also measured. The results show that for all the mixtures tested, the electric energy generation was assured without problems. It has also been observed that the emissions of CO, C_xH_y and SO₂ decrease in the case of diesel–soybean biodiesel blends. The temperatures of the exhaust gases and the emissions of NO and NO_x are similar to or less than those of diesel.     

Use of a dispersed iron catalyst for upgrading extra-heavy crude oil using methane as source of hydrogen

The use of an iron dispersed catalyst, derived from Fe₃(CO)₁₂, for extra-heavy crude oil upgrading using methane as source of hydrogen was studied. The upgrading reactions were carried out batchwise in a stainless-steel 300 ml Parr reactor with 250 ppm of Fe at a temperature of 410-420 °C, a pressure of 11 MPa of CH₄, and a residence time of 1 h. In the presence of Fe₃(CO)₁₂, the reaction of Hamaca extra-heavy crude oil led to a reduction of two orders of magnitude in the viscosity (from 500 to 1.3 Pa s), 14% reduction in sulfur content, and 41% conversion of the >500 °C fraction in the upgraded product with respect to the original crude. The iron catalyst was isolated from the coke produced from the upgrading reaction and was analyzed by XPS, EDAX, and Mössbauer spectroscopy. The results indicated the presence of a Fe-V mixed sulfide species with a composition ca. (Fe_0.6V_0.4)_zS, where z is in the range 0.8-0.9.     

Submicron particle size and polymerization excess surfactant analysis by capillary hydrodynamic fractionation (CHDF)

The particle size distribution of a blend of two polymer latex monodisperse standards, 86 and 238 nm, has been measured by capillary hydrodynamic fractionation (CHDF). The particle size distributions obtained agreed well with the expected particle diameters. The relative amounts of the two standards in the blends were accurately measured at different blend ratios. The particle size distribution of a parenteral lipid sample was successfully measured. A soluble species was fractionated from latex standards smaller than 100nm. This soluble species appears to be excess surfactant used in the preparation of small size monodisperse latexes. The amount of excess surfactant increases as the particle diameter of the standard decreases.     

Soldering mechanisms in materials and coatings for aluminum die casting

The stability against reaction with aluminum of materials and coatings commonly used in aluminum die casting was investigated. The materials considered here were H13 tool steel and Anviloy® 1150, whereas the coatings were TiN and CrN. Special model, freestanding, multilayered thin film structures were used in this study, in association with complementary differential scanning calorimetry and X-ray diffraction. The nature of the reactions (endo or exothermic) and their onset temperatures up to 1273 K were determined. Based on of these results, some activation energies for the different reactions taking place between aluminum and die material or between aluminum and coatings could be established. Different intermetallic compounds were formed in these reactions, which were identified by post mortem X-ray diffraction analysis. Anviloy® 1150 showed superior stability as compared to H13 tool steel, whereas CrN was more inert than TiN coatings. CrN exhibited the best performance among all materials and coatings considered here, although its practical application relies also on adhesion of the CrN coating to the die bulk material. The results are discussed on the lights of two recent models for soldering in aluminum die casting.     

Costs and Benefits of MBE Rules in Construction

The findings of a study designed to investigate the costs and benefits of Minority Business Enterprise (MBE) regulations in the construction industry are presented. The data indicate that large contractors have less difficulty than smaller organizations in meeting MBE requirements. In addition, it is shown that the regulations both benefit and enlarge the number of minority contractors. According to the study, however, MBE procedures have not increased the number of qualified minority contractors. The data also indicate that MBE regulations have increased the cost of construction projects. The amount allocated, although significant when compared to percentage profit, is not substantial. For example, the unweighted values, in terms of construction dollar volume, range from 3.41% for the Engineering News‐Record (ENR) 400 organizations to 3.33% for the Associated General Contractors of Indiana, AGC (Indiana). The weighted values range from 2.04% for the ENR 400 contractors, to 3.74% for the AGC (Indiana). The great majority of firms surveyed indicate that MBE rules and regulations should be modified. Better agency procurement efforts and comprehensive programs to train minority contractors are mentioned as a necessity.