Adaptive reuse of office buildings into housing: opportunities and risks

One way of adapting and reusing vacant office buildings is conversion into housing. Former research has shown possibilities for this type of conversion, and has delivered instruments for determining the conversion potential of vacant offices. Although adaptation and renovation of outdated offices can prove to be a successful property (real estate) strategy, conversions into housing still only occur on a small scale. There are several reasons for this, including uncertainty about financial feasibility and little knowledge about the opportunities and risks of building conversions. A meta-study of the conversion of 15 office buildings into housing in the Netherlands is used to reveal the drivers for office-to-housing conversions as well as the opportunities and risks that arise in the conversion process. The findings show that various legal, financial, technical, functional and architectonic issues define the opportunities and risks of building conversions. These insights can be used to support the decision-making processes for dealing with vacant office buildings in order to minimize the risks and increase the opportunities.     

Influence of injection conditions on EDDS-flushing of metal-contaminated soil

This study evaluated the design of step-gradient, single-pulse, multi-pulse, and continuous injection of biodegradable EDDS ([S,S]-ethylene-diamine-disuccinic acid, under the same total dosage) and the significance of pore-water velocities during in situ soil flushing. In view of the metal breakthrough and extraction efficiency of each injection mode, single-pulse injection was found to be the least effective for all metals. Multi-pulse injection was consistently more effective than single-pulse injection, although the efficiency of second and third pulse injections significantly diminished. Continuous injection offered a simple operation and the greatest Ni and Cu extraction, whereas step-gradient injection was the best option for Zn and Pb extraction because it mitigated the influence of metal exchange. Moreover, a rinsing step with a background solution following the initial injection of the multi-pulse injection removed newly formed metal-EDDS complexes from soil pores effectively before further EDDS-flushing. A decrease in pore-water velocity provided a longer residence time for greater Ni and Cu extraction, but also enhanced the rate-limited metal exchange of Zn-EDDS and Pb-EDDS complexes and thus hindered Zn and Pb extraction. These results suggest a slower and continuous injection for the best Ni or Cu removal, but a faster and step-gradient injection for Zn or Pb removal.     

Magnetic tracking of acoustic radiation force-induced micro-order displacement

The dynamic behavior of a rigid magnetic sphere induced by an acoustic radiation force was investigated. The sphere was suspended in water in a simple pendulum configuration. The drag force acting on the pendulum during its motion was considered to follow a modified Stokes law for a low Reynolds number, accounting for phenomena related to its oscillatory movement. Steady forces of long (a few seconds) and short (a few milliseconds) durations were used. The movement of the magnetic sphere was tracked using a magnetoresistive sensor. From the new equilibrium position of the sphere in response to the long-duration static radiation force, the amplitude of this force was estimated. To assess the water viscosity, the relaxation movement after the acoustic force had stopped was fitted to a harmonic-motion model. Based on the results for the acoustic force and water viscosity, a theoretical profile of the sphere's micro-order displacement as a function of time caused by short-duration acoustic radiation force agreed well with experimental results.     

Melt-spun poly(tetrafluoroethylene) fibers

The recent discovery of melt-processable poly(tetrafluoroethylene) (PTFE) allows for common thermoplastic-polymer processing technologies to be applied to this unique polymer, which heretofore was considered to be highly intractable. In this paper, we report simple melt-spinning of monofilaments of a set of melt-processable (modified) PTFE grades with weight-average molar masses (M _w) ranging from 77 to 292 kg/mol. Fibers were spun at 380 °C at draw-down ratios of up to 2,750, yielding filaments of linear densities as low as 0.8 tex, corresponding to a diameter of ∼20 μm. The maximum Young’s modulus and tensile strength of as-spun fibers produced in this study were 91.7 cN/tex (1,972 MPa) and 12.0 cN/tex (258 MPa), respectively, accompanied by a strain to break of 24%.     

Modifiable stroke risk factors in volunteers willing to participate in a prevention program

The current trends in stroke incidence require continued efforts to improve primary prevention. Compared to large-scale public health approaches, more limited programs targeting volunteers may offer some advantages. We invited all 12,824 members of a health insurance company program who lived within 50 km form one of two study sites to participate in a vascular screening program and aimed at reducing modifiable risk factors. 1,837 persons registered and participated (14.3%, mean age 53 +/- 12 years, 50% men). Using the Framingham stroke risk profile for persons aged 55 years or above (n = 961, 52.3%), 97 stroke events can be predicted for this age group within 10 years. The majority of these 97 events will occur in those with men resting blood pressure values +/- 140mm Hg (systolic) or +/- 90 mm Hg (diastolic; 420 persons, mean age 64 +/- 7 years, 60 expected events), or with a particularly high age- and sex-adjusted risk (288 persons, mean age 68 +/- 7 years, 60 expected events). Our pilot study provides an estimate of the prevalence of modifiable vascular risk factor among volunteer participants of a prevention program. Possible benefits of this approach will be investigated in a second step using a randomized intervention.     

Therapy of acute myocardial infarct (1994-1996) at non-university hospitals in Switzerland (CHAMI Study)

The CHAMI study (Confederatio Helvetica Acute Myocardial Infarction) recorded the therapies administered for acute myocardial infarction in 520 consecutive patients between October 1994 and February 1996 at 10 non-academic hospitals in Switzerland. The patients in this group consisted of 363 men and 157 women with an average age of 63.2 years. The prescribed medications administered from the day of hospital admission until the day of discharge were recorded. In the acute phase, the patients were given the following therapy: thrombolytic agents 40%, i.v. nitrates 65%, i.v. beta-blockers 22%, aspirin 95%, oral beta-blockers 36%, ACE inhibitors 14%. Impressive was the lower distribution of thrombolytic agents and beta-blockers among the older patients (age > 70) (thrombolytic agents 52.1% vs 28.4%; oral beta-blockers 44.0% vs 29.1%) and in particular among women (thrombolytic agents 26.8% vs 46%; oral beta-blockers 29.3% vs 39.7%) in men. Therapy at hospital discharge consisted, inter alia, of aspirin (73%), beta-blockers (54%), ACE inhibitors (3%), and lipid lowering agents (10%). The hospital mortality was 12.6%. The CHAMI study provided the participating hospitals with a quality control comparison with other participating centers and impressively demonstrated with the example of the lipid lowering agents, that the significance of secondary prophylaxis is assigned too little importance in contrast to acute therapy.     

Estimation of Bridging Interactions for Natural Cracks from Bending Strength of Coarse-Grained Al2O3

Several ceramic materials show R -curve effects which in the past were investigated mainly with specimens containing artificial macrocracks. This paper describes how the R -curve effects caused by bridging interactions between the crack surfaces will influence the strength of specimens with natural crack populations. Calculations in terms of averaged stress intensity factors were performed to describe the development of surface cracks from the initial size up to the size at failure. As a consequence of bridging interactions, deviations from the expected straight line in the Weibull representation of strength will occur even under the assumption that the initial crack size is Weibull-distributed. A least-squares procedure allows the bridging stresses to be estimated from bending strength measurements.     

Buffer gases to increase the efficiency of an optically pumped far infrared D2O laser

The effects of buffer gas additives on the performance of an optically pumped D2O laser operating at 385 μm have been investigated both experimentally and by numerical simulation. Three gases, sulphur hexafluoride, carbon tetrafluoride, andn-hexane, were found to produce an increase of up to 40 percent in the pumping efficiency, as well as significant lengthening of the far infrared pulse. Under optimum conditions, 2.6 J in a 1 μs long pulse have been obtained. The buffer gases are shown to eliminate the vibrational deexcitation bottleneck, which in pure D2O leads to an accumulation of population in the upper vibrational leve and, hence, a reduction in the efficiency of absorption of the pump beam. Comparison of the observed buffer gas effects with the predictions of a numerical simulation code based on a rate equation model gives information about the constants for vibrational and rotational relaxation rates due to D2O-D2O and D2O-buffer gas collisions.