Direct observations of colloid retention in granular media in the presence of energy barriers, and implications for inferred mechanisms from indirect observations

In this paper we present direct observations of retention of colloids in granular porous media over a large size range (0.21-9.0 μm) and generalize the significance of attachment in grain to grain contacts and attachment on the open surface as a function of colloid:collector ratio. We examine reversibility of attachment via these mechanisms with respect to ionic strength reduction and fluid velocity increase. We relate these direct observations to existing literature, and in some cases offer alternative interpretations of mechanisms of retention drawn from indirect observations (e.g. via column effluent and retained concentrations).     

Redox and pH Dual Responsive Polymer Based Nanoparticles for In Vivo Drug Delivery

Responsive nanomaterials have emerged as promising candidates as drug delivery vehicles in order to address biomedical diseases such as cancer. In this work, polymer‐based responsive nanoparticles prepared by a supramolecular approach are loaded with doxorubicin (DOX) for the cancer therapy. The nanoparticles contain disulfide bonds within the polymer network, allowing the release of the DOX payload in a reducing environment within the endoplasm of cancer cells. In addition, the loaded drug can also be released under acidic environment. In vitro anticancer studies using redox and pH dual responsive nanoparticles show excellent performance in inducing cell death and apoptosis. Zebrafish larvae treated with DOX‐loaded nanoparticles exhibit an improved viability as compared with the cases treated with free DOX by the end of a 3 d treatment. Confocal imaging is utilized to provide the daily assessment of tumor size on zebrafish larva models treated with DOX‐loaded nanoparticles, presenting sustainable reduction of tumor. This work demonstrates the development of functional nanoparticles with dual responsive properties for both in vitro and in vivo drug delivery in the cancer therapy.     

Effect of beam voltage on the properties of aluminium nitride prepared by ion beam assisted deposition

The effects of nitrogen-beam voltage on the structure, stress, energy band gap and hardness of AIN thin films deposited on Si (111), Si (100) and sapphire (0001) by ion beam assisted deposition (IBAD) are reported. As the nitrogen-beam voltage was increased from 50 to 200 V, the stress and disorder in the AIN films increased as determined by X-ray diffraction, FTIR and Raman spectroscopy. The preferred orientation of the film's c-axis changed from completely normal to the film at 100 V, to a mixture of normal and in the plane of the film at 200 V. For AIN films deposited under the same conditions, the films were more highly oriented on sapphire (0001) than in Si (111). The hardness of the films increased from 18.2 to 23.7 GPa with the nitrogen-beam voltage, and possible reasons for this change in hardness are considered.     

Potential application of gas chromatography/tandem mass spectrometry in the measurement of coeluting isomers

Despite the unprecedented popularity of separation chromatography, the measurement of coeluting isomeric chemicals remains an extremely difficult task. We developed an analytical scheme capable of measuring two coeluting isomers using a single chromatographic column and a gas chromatography/tandem mass spectrometry system. The protocol utilized two product ion fragments generated from a common parent ion associated with the isomers for quantitation. The utility of the analytical scheme was demonstrated with the measurements of several pairs of coeluting polychlorinated biphenyl (PCB) isomers in standard solutions and fish liver samples. Best results were given when a set of stringent constraints for the abundance ratio of the two product ion fragments was satisfied. Analyses of seven fish liver samples collected from nearshore San Diego, CA, indicated that the domain that had been previously reported to comprise PCB 153 and PCB 168 actually contained PCB 153 only. Although only a selected number of PCB congeners were examined, the results presented indicate that the analytical scheme has the potential to be used to determine the concentrations of all chromatographically coeluted isomers.     

A continuous-review model for dual intercontinental and domestic outsourcing

When making sourcing decisions, many firms consider only the direct and most visible supply-chain costs, such as unit production costs and ocean-shipping costs. Often ignored are the hidden direct and indirect costs in long supply chains, and their impact on profitability. As supply chains lengthen, supply-chain disruptions undercut the ability of manufacturers and retailers to satisfy market demands. Supply-chain disruptions add costs by forcing companies to increase inventories, to juggle production and shipping schedules, to incur excessive backordering, and to airfreight or discount the prices of goods that were not in the right place at the right time. The question is, can higher incidence of supply-chain disruptions in intercontinental supply chains justify keeping the domestic suppliers? To address the question, this paper presents a hybrid continuous-review inventory model for dual intercontinental and domestic outsourcing. The conditions for domestic outsourcing only, for intercontinental outsourcing, and for dual outsourcing were established. The problem of minimising the long-run average cost of outsourcing was investigated, and mathematical optimisation was used to illustrate the model. It is shown that if the cost of service failure outweighs the cost differential between domestic and intercontinental outsourcing, keeping domestic suppliers may be a good option.     

Thermal performance indicators for refrigerated road vehicles

An experimental evaluation of insulation effectiveness, pull-down times and effectiveness of a mechanical refrigeration unit was performed on five refrigerated panel vans. Additionally, a mapping of temperature variability in the cargo space was carried out during a simulated journey encompassing several door openings. The temperature variability measured in the vans was neither correlated to the effectiveness of the insulation nor the time required to achieve complete cooling of the cargo space. These criteria are common thermal performance indicators used to evaluate refrigerated vehicles in international standards. The efficiency of insulation was correlated to the pull-down times, presenting the possibility of calculating the former as a function of the latter. The temperature variability was correlated with the time required for the unit to recover temperature control after a door opening and the difference between the maximum and minimum temperatures reached during a door opening cycle.     

Role of nitrogen lewis basicity in boronate affinity chromatography of nucleosides

Urinary modified nucleosides have a potential role as cancer biomarkers, and most of the methods used in their study have utilized low-pressure phenylboronate affinity chromatography materials for the purification of the cis-diol-containing nucleosides. In this study, a boronate HPLC column was surprisingly shown not to trap the nucleosides as would be expected from experience with the classic Affigel 601 resin but showed only partial selectivity toward cis-diol groups while other groups exhibited better retention. In aprotic conditions, trapping of nucleosides was possible; however, the selectivity toward cis-diol-containing compounds was lost with the Lewis basicity of available nitrogens being the main determinant of retention. The experimental findings are compared to and confirmed by DFT calculations.     

A model for the transverse strain response of unidirectional ceramic matrix composites during tensile testing

A comprehensive micromechanical model relating the longitudinal stress and transverse strain of unidirectional fibre toughened ceramic matrix composites (CMCs) is presented. The model uses different cylindrical unit-cells to describe the composite throughout a tensile test and considers all relevant damage mechanisms. The proposed model takes into account the Poisson contraction of fibre and matrix, the relief of thermal residual stresses upon damage development, and the build-up of compressive radial stresses at the interface due to mismatch between fibre and matrix after debonding and sliding. Thus the modelled transverse strain response depends on a wide range of microstructural and micromechanical parameters. The approach is checked by comparing the experimentally observed and simulated response of a unidirectional SiC/CAS composite of which all constituent properties were determined experimentally. The agreement between experiment and theory is excellent.