Effect of spacer arm length on protein retention on a strong cation exchange adsorbent

The retention of five proteins was compared on a set of three strong cation exchange adsorbents that differed in spacer arm chemical structure and length. The adsorbents included a commercial product, Amersham Biosciences SP Sepharose Fast Flow, containing a six-carbon spacer between the agarose matrix and the anionic ligand, and two custom-prepared materials. One of the custom adsorbents contained a spacer of about half the length of the SP Sepharose Fast Flow, and the other contained no spacer arm. The adsorbent with no spacer arm was found to be significantly more retentive for all of the test proteins examined, in both isocratic and gradient elution tests. Reducing the spacer arm length by half resulted in increased retention for four of the five proteins, but this increase was less than what was observed when the spacer arm was eliminated. Retention increases were obtained without increasing the density of the anionic charge groups and appear to result from an enhancement of electrostatic or secondary nonelectrostatic interactions, or both. The results indicate that spacer arm length may be a useful variable in manipulating stationary-phase retention properties.     

Binary monolayers of single-stranded oligonucleotides and blocking agent for hybridisation

The hybridisation of thiol-modified single-stranded DNA (SH-ssDNA) embedded in lipoate or hydrophilic polymer monolayers on gold have been studied through the technique of surface plasmon resonance (SPR). SH-ssDNA and the blocking agents were co-adsorbed on gold from the same solution or the surface was post-treated with the blocking agents. The assembling process is allowed to take place for only 10 min. Binding of non-complementary and complementary DNA is dependent both on the blocking agent and on the assembling method used. The lowest non-complementary binding and the highest complementary binding of DNA was obtained with a layer assembled from a binary solution of SH-ssDNA and the lipoate blocking agent.     

Comparative emission analysis of low-energy and zero-emission buildings

Different designs and concepts of low-energy and zero-emission buildings (ZEBs) are being introduced into the Norwegian market. This study analyses and compares the life cycle emissions of CO₂ equivalents (CO₂e) from eight different single-family houses in the Oslo climate. Included are four ZEBs: one active house, two passive houses, and a reference house (Norwegian building code of 2010). Monthly differences in CO₂e emissions are calculated for the seasonally sensitive Norwegian context for electricity generation and consumption. This is used to supplant the previous applied symmetric weighting approach for CO₂e/kWh factors for import and export of electricity for the ZEB cases. All the ZEBs have lower use-stage emissions compared with the other buildings or the reference case. Embodied impacts are found to be 60–75% for the analysed ZEB cases, confirming the importance of embodied impacts in Norwegian ZEBs. The lowest total emissions were from the smallest ZEB, emphasizing area efficiency. The highest emissions were from the reference case. By abandoning the symmetric approach, a new perspective was developed for assessing the performance of ZEBs within the Norwegian context. One of four ZEB cases managed to balance out its annual energy-related emissions.     

The impact of a call centre on communication in a programme and its projects

Call centres are increasingly being utilised in public sector programmes to facilitate and manage communication between numerous stakeholders. Yet, the impact of call centres on projects has not been investigated. This paper reports on a survey with 92 respondents that assessed the impact of a call centre for a repair and maintenance programme. An empirically verified model is presented to illustrate the relationship between call centre communication and project performance. A balance of frequent informal and formal communication is shown to reduce mistrust and conflict of interest resulting from each party trying to maximise his respective economic position in the principal–agency relationship. The data provides evidence that a call centre improves the communication, collaboration and trust in project principal–agency relationships which, in turn, is perceived to contribute to project performance.     

Urban infrastructure: four perspectives on Swedish development

From an international perspective, Sweden enjoys a leading position concerning urban infrastructure as the industrialized world is struggling with similar problems. In many countries, the situation is critical. By taking advantage of the short channels of communication between the central and the local governmental bodies, researchers and industry in Sweden can develop knowledge of interest to the entire international community. This feature article combines four essays by leading Swedish experts in the field of infrastructure development.     

Ion probe technique for the study of gallium diffusion in silicon nitride films

The penetration of Ga in films of amorphous Si₃N₄ about 2000 Å thick on Si substrates has been studied. The films were produced by pyrolysis. Diffusion profiles were obtained by surface exposure to Ga vapor, and the implantation profiles by ion bombardment in an isotope separator. Evaluation of the profiles was effected by means of sputtering in a secondary ion microanalyzer. For depth calibration, ion yield profiles of ⁶⁹Ga⁺ of ⁷¹Ga⁺ were compared with the profiles of ³⁰Si⁺, ⁷⁰(Si₂N⁺, SiN⁺₃) and ⁷²Si₂O⁺. The integration of implantation peaks furnished a means of obtaining absolute values of Ga concentrations from the secondary ion intensities. Hence the surface concentration of vapor-deposited Ga at 1100°C was assessed to be of the order of 8 × 10²⁰ atoms cm^-3. The diffusion coefficient of Ga in Si₃N₄ at 1100°C was found to be about 5 × 10^-17 cm² s^-1. The method, which combines sputtering and mass spectrometry, appears to be applicable for measuring diffusion coefficients in this system down to about 3 × 10^-18 cm² s^-1.     

Nonpharmacological interventions for insomnia in older adults: A meta-analysis of treatment efficacy.

The benefit of nonpharmacological interventions for insomnia in old age was investigated. A total of 13 single-outcome studies from 1966–1998 involving 388 patients (mean age exceeding 60 years, minimum age in sample, 50 years) were included in a meta-analysis of treatment efficacy. This analysis demonstrated that behavioral interventions produce improvements in sleep parameters of older insomniacs, measured in terms of sleep-onset latency, number of nocturnal awakenings, time awake after sleep onset, and total sleep time. Clinical improvements seen at posttreatment were maintained at followups (averaging 6 months). It is concluded that behavioral treatments produce significant and long-lasting improvements in the sleep pattern of older insomniacs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hydrogen Oxidation Catalyzed by Pt Supported on Carbon Nanofibers with Different Graphite Sheet Orientations

The kinetic study of hydrogen oxidation with or without the presence of CO has been used as a tool to study the relative oxygen and CO adsorption strength on Pt nanoparticles, which are important parameters for fuel cell catalysts. It was found that the activation energy, which is determined by the oxygen binding energy, is influenced by the CNF graphite sheet orientation, CNF oxygen groups and catalyst preparation method. A weaker bonding of oxygen was indicated for Pt nanoparticles supported on platelet compared to Pt on fishbone CNFs. Moreover, oxygen seemed to be more strongly bonded to Pt particles on CNFs prepared by deposition–precipitation compared to those prepared by incipient wetness impregnation and a metal-oxide colloid method. Enhanced CO-adsorption was indicated for Pt supported on carbon nanofibers with introduced oxygen groups.     

Micro-fibre and ultra-micro-fibre cloths, their physical characteristics, cleaning effect, abrasion on surfaces, friction, and wear resistance

The properties of 12 micro-fibre cloths and two ultra-micro-fibre cloths were studied and compared with conventional cleaning methods. The cloths made from micro-fibre and ultra-micro-fibre had very good cleaning effect. Scrubbing Plexiglas caused pitting and scratch marks on the Plexiglas surface with the largest damage being caused in dry condition. All the cloths tested were wear resistant. Most of the cloths showed high friction against the surfaces in damp condition. Micro- and ultra-micro-fibre cloths are good alternatives to conventional methods for cleaning interior surfaces. Furthermore, good cleaning results can be achieved without any use of polluting cleaning chemicals.