In vitro mesenchymal stem cell responses on laser-welded NiTi alloy

The biocompatibility of NiTi after laser welding was studied by examining the in vitro (mesenchymal stem cell) MSC responses at different sets of time varying from early (4 to 12 h) to intermediate phases (1 and 4 days) of cell culture. The effects of physical (surface roughness and topography) and chemical (surface Ti/Ni ratio) changes as a consequence of laser welding in different regions (WZ, HAZ, and BM) on the cell morphology and cell coverage were studied. The results in this research indicated that the morphology of MSCs was affected primarily by the topographical factors in the WZ: the well-defined and directional dendritic pattern and the presence of deeper grooves. The morphology of MSCs was not significantly modulated by surface roughness. Despite the possible initial Ni release in the medium during the cell culture, no toxic effect seemed to cause to MSCs as evidenced by the success of adhesion and spreading of the cells onto different regions in the laser weldment. The good biocompatibility of the NiTi laser weldment has been firstly reported in this study.     

Parallel implementation of the biorthogonal multiresolution time-domain method

The three-dimensional biorthogonal multiresolution time-domain (Bi-MRTD) method is presented for both free-space and half-space scattering problems. The perfectly matched layer (PML) is used as an absorbing boundary condition. It has been shown that improved numerical-dispersion properties can be obtained with the use of smooth, compactly supported wavelet functions as the basis, whereas we employ the Cohen-Daubechies-Fouveau (CDF) biorthogonal wavelets. When a CDF-wavelet expansion is used, the spatial-sampling rate can be reduced considerably compared with that of the conventional finite-difference time-domain (FDTD) method, implying that larger targets can be simulated without sacrificing accuracy. We implement the Bi-MRTD on a cluster of allocated-memory machines, using the message-passing interface (MPI), such that very large targets can be modeled. Numerical results are compared with analytical ones and with those obtained by use of the traditional FDTD method.     

The importance of language in international knowledge transfer

Abstract and Key Results

Kinetics of zero-valent iron reductive transformation of the anthraquinone dye Reactive Blue 4

The effect of operational conditions and initial dye concentration on the reductive transformation (decolorization) of the textile dye Reactive Blue 4 (RB4) using zero-valent iron (ZVI) filings was evaluated in batch assays. The decolorization rate increased with decreasing pH and increasing temperature, mixing intensity, and addition of salt (100 g L⁻¹ NaCl) and base (3 g L⁻¹ Na₂CO₃ and 1 g L⁻¹ NaOH), conditions typical of textile reactive dyebaths. ZVI RB4 decolorization kinetics at a single initial dye concentration were evaluated using a pseudo first-order model. Under dyebath conditions and at an initial RB4 concentration of 1000 mg L⁻¹, the pseudo first-order rate constant (k_obs) was 0.029 ± 0.006 h⁻¹, corresponding to a half-life of 24.2 h and a ZVI surface area-normalized rate constant (k_SA) of 2.9 × 10⁻⁴ L m⁻² h⁻¹. However, as the initial dye concentration increased, the k_obs decreased, suggesting saturation of ZVI surface reactive sites. Non-linear regression of initial decolorization rate values as a function of initial dye concentration, based on a reactive sites saturation model, resulted in a maximum decolorization rate (V_m) of 720 ± 88 mg L⁻¹ h⁻¹ and a half-saturation constant (K) of 1299 ± 273 mg L⁻¹. Decolorization of RB4 via a reductive transformation, which was essentially irreversible (2–5% re-oxidation), is believed to be the dominant decolorization mechanism. However, some degree of RB4 irreversible sorption cannot be completely discounted. The results of this study show that ZVI treatment is a promising technology for the decolorization of commercial, anthraquinone-bearing, spent reactive dyebaths.     

Silica-precipitating peptides isolated from a combinatorial phage display peptide library

Many biological organisms contain specialized structures composed of inorganic materials. Cellular processes in vivo facilitate the organized assembly of mineral building blocks into complex structures. The structural hierarchy and complexity across a range of length scales are providing new ideas and concepts for materials chemistry. Proteins that direct biomineralization can be used to control the production of nanostructured materials and facilitate the fabrication of new structures. Here, we demonstrate that some of the silica-binding peptides isolated from a combinatorial phage peptide display library can be used in precipitating silica from a solution of silicic acid. The results described in this report demonstrate that peptides displayed by phages act as templates in inorganic material synthesis and provide a means of understanding how some of the biological systems may be carrying out materials chemistry in vivo.     

Evaluating the crash and citation rates of Utah drivers licensed with medical conditions, 1992-1996

BACKGROUND: Medical problems may affect the ability to drive motor vehicles, and programs that control the issuing of driver licenses to individuals with medical conditions exist in most states. The main activity of these programs is the imposition of restrictions upon the driving privileges of individuals with medical conditions that are deemed to pose some risk to public safety. However, little is known about the effectiveness of these licensing programs. OBJECTIVE: The objective of this study was to compare the rates of adverse driving events (crash, at-fault crash and citations) experienced by drivers licensed with medical conditions to those of age-, sex- and location-matched controls. Separate comparisons were made for drivers reporting medical conditions licensed with full driving privileges, and those with restricted driving privileges (e.g. speed, area and time of day). DESIGN: Retrospective case-control. METHODS: The study population was all drivers licensed in the state of Utah who reported a medical condition on their driver license application, over the 5-year period 1992-1996. Drivers enter the program by self-reporting their medical problems. Control drivers were chosen from the entire population of drivers licensed in Utah for the same period. Information on driver license status, participation in the medical conditions program, citations, involvement in crashes, and death certificate data was obtained from the relevant state agencies. Probabilistic linkage methodology was used to link the records in these disparate databases for eventual analysis. Rates of citation, crashes and at-fault crashes, expressed as events per 10000 license days, were calculated separately for program drivers and their corresponding control groups for each medical condition category and restriction status. These data were used to determine an estimate of relative risk (RR) and 95% confidence intervals. Results: As a group, medical conditions drivers had modestly elevated rates of adverse driving events compared with control drivers (RR 1.09-1.74). Rates in the largest medical category, 'cardiovascular conditions', were not higher than controls. Rates were higher than control for some conditions, such as 'alcohol' and 'learning and memory', for some adverse events (RR 2.2 -5.75). Drivers with more than one medical condition appeared comparable to the general group of medical conditions program drivers. CONCLUSIONS: Drivers in Utah medical conditions program had modestly elevated rates of adverse driving events compared to matched controls. Possible underreporting of medical conditions and accurate assessment of exposure rates are potential weaknesses in the program.     

Understanding the Role of Self‐Efficacy in Engineering Education

The engineering professor's role is dualistic in the sense that not only must s/he create an academic environment conducive to the acquisition of course content but must also prepare students to become practicing professionals. This dualism requires that the professor both motivate good study habits as well as build within students the confidence that they have the requisite capability to perform actual engineering. Self‐efficacy, simply defined as one's self‐judgment concerning capability, has been shown to be an important mediating factor in cognitive motivation. This paper describes the motivating role of the professor, theories of motivation, the role of self‐efficacy in motivation, and guiding principles that can be used to enhance self‐efficacy in engineering students. These principles can serve as guidelines in designing instructional delivery strategies that motivate engineering students to engage in behaviors conducive to becoming value‐added practitioners.     

Development of a design space and predictive statistical model for capsule filling of low-fill-weight inhalation products

The objectives of this study were to develop a predictive statistical model for low-fill-weight capsule filling of inhalation products with dosator nozzles via the quality by design (QbD) approach and based on that to create refined models that include quadratic terms for significant parameters. Various controllable process parameters and uncontrolled material attributes of 12 powders were initially screened using a linear model with partial least square (PLS) regression to determine their effect on the critical quality attributes (CQA; fill weight and weight variability). After identifying critical material attributes (CMAs) and critical process parameters (CPPs) that influenced the CQA, model refinement was performed to study if interactions or quadratic terms influence the model. Based on the assessment of the effects of the CPPs and CMAs on fill weight and weight variability for low-fill-weight inhalation products, we developed an excellent linear predictive model for fill weight (R^2?=?0.96, Q^2?=?0.96 for powders with good flow properties and R^2?=?0.94, Q^2?=?0.93 for cohesive powders) and a model that provides a good approximation of the fill weight variability for each powder group. We validated the model, established a design space for the performance of different types of inhalation grade lactose on low-fill weight capsule filling and successfully used the CMAs and CPPs to predict fill weight of powders that were not included in the development set.     

Academic performance and institutional resources: a cross-country analysis of research universities

Links between institutional academic performance and academic resources are of relevance for university managers, country officials and the public at large. This study aims to shed light on the issues using reliable data on research performance indicators as well as educational and resource indicators from research universities in Spain, Italy, Australia and Canada. The four countries selected for the study represent different academic traditions and belong to different geopolitical regions, yet they have relatively similar higher education systems in terms of student population, institutional resources and research production. Our study explores differences and similarities among them to better assess the performance of research universities from the four countries in a global context. The indicator set includes research production (number of indexed articles per year) and its quality (citation impact and number of highly cited papers), education production (full-time equivalent FTE student load and degree completions per year) and the resource base (annual ordinary expenditure and FTE number of faculty). We consider the raw indicators as well as a set of composite indicators normalised by measures of scale. Across the profile of universities in our complete sample, institutional size is the prime determinant of research production, with systematic differences in quality related to country, research intensity and resourcing level. Our data show that research universities allocate resources to research and education in country-specific and size-specific ways that are reflected in research performance.