An example of in-plant noise reduction with an acoustical barrier

Existing theories for predicting the distribution of sound intensity in rooms and the performance of acoustical barriers are applied in designing a barrier to reduce noise in an industrial environment. The combination of the theories is found to predict the sound pressure level in the barrier shadow zone reasonably well.     

Radiation induced oxidative degradation of poly[bis(p-tolylamino)] phosphazene in chlorinated hydrocarbons

Degradation induced by ionizing radiations on polyphosphazenes, dissolved in chlorinated methanes, is the subject of this investigation. Both steady gamma and pulse radiolysis techniques have been employed.The labile sites for radical attack in poly[bis(p-tolylamino)] phosphazene were identified as the aniline N-H and benzyl C-H bonds of the pendant groups. All the primary radicals, by themselves or after peroxidation, can give rise to macroradicals by hydrogen abstraction from the polymer molecules. Appreciable crosslinking appeared only in the presence of quite a high concentration of oxygen, whereas, in its absence or after it had been consumed, practically no $\text{M}{}_{\mathrm{<mtext>w</mtext>}}$ changes were detected. Optical spectra of intermediates formed after pulse radiolysis are reported and attributed to radical-polymer charge transfer complexes, anilinium ions and toluidine radicals. p-Toluidine is formed as an end-product by hydrogen abstraction from polymer molecules. In solvents where hydrogen chloride can be formed, the amino functional group is affected.     

Effects of 60Co gamma rays on poly[bis(p-tolylamino)Phosphazene]

The behaviour of poly-[bis(p-tolylamino)phosphazene] under ⁶⁰Co gamma irradiation was investigated in chloroform, carbon tetrachloride, benzene, toluene and tetrahydrofuran. Viscosity, average molecular weights and spectral changes were used to follow the degradation. The degradation mechanism was interpreted in terms of a combined interaction of the polymer molecule with dissolved oxygen and radiolysis products of the solvent.     

Divide and conquer: the engineering of delegation

Computational Management Science - Members of an organization have conflicting preferences. Principal-agent theory analyzes how and under which conditions this conflict can be resolved by means of...     

Contributions of 3D Printed Fracture Networks to Development of Flow and Transport Models

Transport in Porous Media - Conventional experiments using natural rock samples have trouble in observing rock structures and controlling fracture properties. Taking advantage of 3D printing...     

Photochemical behaviour of poly-(organophosphazenes)—II. Oxygen influence on the photodegradation of aryloxy- and arylamino-substituted polyphosphazenes in solution

The photodegradations of poly-[bis(β-naphthoxy)] phosphazene and poly-[bis(p-tolylamino)] phosphazene were investigated in methylene chloride solution. A mechanism has been proposed to explain the influence of molecular oxygen on the photoprocesses. Molecular weight variations, results of flash photolysis experiments and the observed post-photochemical effect are in agreement with the suggested mechanism.     

Solid-state NMR spectroscopic studies of an integral membrane protein inserted into aligned phospholipid bilayer nanotube arrays

This communication demonstrates for the first time that solid-state NMR spectroscopic studies can be used to investigate aligned phospholipid bilayer nanotube arrays. Also, an integral membrane peptide can be successfully incorporated into the oriented phospholipid bilayer nanotube arrays and studied with 2H solid-state NMR spectroscopy.     

The conversion of an aziridine plus a phenyl-substituted amine oxide or aminoether to a benzodiazepine derivative

The conversion of an aziridine to a tetrahydrobenzodiazepine derivative using LiI, an iron carbonyl complex, and an amine oxide, or using LiI and a gem-aminoether is studied. The reaction of an aziridine with LiI and a phenyl-substituted iminium salt generates mainly a 1,2-diamine. The addition of t-butoxide to the iminium reaction changes the product ratio leading to a diamine as the minor product and a benzodiazepine as the major product. The structure proof of the tetrahydrobenzodiazepine derivative and the mechanism of these transformations are discussed.     

Bond strength of Epiphany™ Sealer combined with different adhesive systems photo-activated with LED and QTH

The Epiphany? Sealer is a new dual-curing resin-based sealer and has been introduced as an alternative to gutta-percha and traditional root canal sealers. The canal filling is claimed to create a seal with the dentinal tubules within the root canal system producing a ‘monoblock’ effect between the sealer and dentinal tubules. Therefore, considering the possibility to incorporate the others adhesive systems, it is important to study the bond strength of the resulting cement. Forty-eight root mandibular canines were sectioned 8-mm below CEJ. The dentine discs were prepared using a tapered diamond bur and irrigated with 1% NaOCl and 17% EDTA. Previous the application Epiphany? Sealer, the Epiphany? Primer, AdheSE, and One Up Bond F were applied to the root canal walls. The LED and QTH (Quartz Tungsten Halogen) were used to photo-activation during 45 s with power density of 400 and 720 mW/cm², respectively. The specimens were performed on a universal testing machine at a cross-head speed of 1 mm/min until bond failure occurred. The force was recorded and the debonding values were used to calculate Push-out bond strength. The analysis of variance (ANOVA) and Tukey’s post-hoc tests showed significant statistical differences (P < 0.05) to Epiphany? Sealer/Epiphany? Primer/QTH and EpiphanyTM Sealer/AdheSE/QTH, which had the highest mean values of bond strength. The efficiency of resin-based filling materials are dependent the type of light curing unit used including the power density, the polymerization characteristics of these resin-based filling materials, depending on the primer/adhesive used.