Moisture Accumulation and Its Impact on the Thermal Performance of Pipe Insulation for Chilled Water Pipes in High Performance Buildings

Mechanical pipe insulation systems are commonly applied to cold piping surfaces in most industrial and commercial buildings in order to limit the heat losses and prevent water vapor condensation on the pipe exterior surfaces. Due to the fact that the surface temperature of these pipelines is normally below the ambient dew point temperature, water vapor diffuses inside the pipe insulation systems and often condenses when it reaches the pipe exterior surfaces. The water droplets accumulated in the pipe insulation system increase its overall thermal conductivity by thermal bridging the cells or the fibers of the insulation material. The moisture ingress into pipe insulation threatens the thermal performance and the overall efficiency of the building mechanical system. This phenomenon is also responsible for the mold growth inside occupied spaces and causes the pipelines to be more vulnerable to corrosion. Although a wide range of vapor barriers are used for preventing water vapor penetration into pipe insulation, common experience in the field shows that water vapor will inevitably ingress into the insulation materials from the end joints or from the cracks created during insulation installation. How to account for the moisture ingress on pipe insulation service life and thermal performance is still an open question. Thermal conductivity is one of the most important properties for evaluating the thermal performance of the pipe insulation systems. Using a new test apparatus, the thermal conductivity of pipe insulation systems below ambient temperature and in wet conditions with moisture ingress was measured. Fiberglass and phenolic pipe insulation were tested to investigate the moisture effects on the material thermal conductivity. The data showed that these two types of pipe insulation systems had quite different water absorption rates due to different characteristics of the material and its structure. A serious degradation of fiberglass pipe insulation thermal performance was observed and the thermal conductivity increased by as much as 3 times when the moisture content was about 12 percent in volume. Tested at a different condition, the thermal conductivity of phenolic pipe insulation increased to 1.6 times of the original value and the moisture content was 5% in volume. Considering the gravity effect, the moisture content on the top and bottom C-shells were separately measured and discussed in this paper

Bee-Friendly Beef: Developing Biodiverse Pastures to Increase Ecosystem Services

The capacity of grasslands to provide ecosystem services, such as pollinator resources, is often limited by lack of plant biodiversity. This is true of grasslands in the eastern US that are dominated by tall fescue (Festuca arundinacea) a non-native, cool-season grass that is typically toxic to cattle. This paper summarizes a research project in Virginia, USA exploring the idea that ecosystem services provided by tall fescue-dominated grasslands can be improved by increasing the plant biodiversity available to beef cattle and bees. Within three 6.5 ha tall fescue grasslands, we established 0.8 ha plots with a 17 species mix of native warm-season grasses (NWSGs) and wildflowers. Beginning in 2018, we measured grass and wildflower establishment, attractiveness of wildflowers to bees, abundance and diversity of bee communities in biodiverse pastures and adjacent tall fescue pastures. Many of the 18 species sown established well expect for NWSGs. Competition from wildflowers likely suppressed native grasses and limited forage availability for beef cattle. Cattle largely ignored the wildflowers. This finding suggests that cattle and pollinators can share this biodiverse grassland as their primary foods are mutually exclusive. The total number of bees was almost double in wildflower-enhanced grasslands compared with more typical tall fescue grasslands. We observed most bee landings on purple coneflower (Echinacea purpurea) and anise hyssop (Agastache foeniculum). Several weedy species such as milkweed (Asclepias syriaca) and musk thistle (Carduus nutans) were also attractive to bees. Preliminary analyses identified at least 28 bee morphospecies and a distinct bee community present in wildflower pastures. While these results were promising, more research is needed on ways to establish biodiverse grasslands so that a more optimal balance of grasses and wildflowers can be sustained to benefit both cattle production and pollinators

Feasibility of the implementation of solar heat sources for bridge deck applications

Deicing salts have caused damage and early failure of the concrete cover and corrosion of reinforcing steel of concrete bridge decks. The use of wax to internally seal Portlant Cement concrete bridge decks and the use of monomers to polymerize concrete have been researched as methods to repair deteriorated decks and to prevent the penetration of salt into the conrete. Both methods require heating the concrete to a depth of two inches to temperatures of 160 to 190 degrees F. Eelctrical and propane heating systems are expensive to buy and operate. Solar equipment may be more simple and uses a source of energy that is both free and non-polluting. the installation of two cathodic protection systems as part of the Federal Highway Administration's Demonstration Project No. 34, "Cathodic Protection for Reinforced Concrete Bridge Decks". Two different types of cathodic protection systems were installed under this contract. The first system known as a "slotted" or non-overlay system consists of anodes which are installed in slots that have been sawed in the bridge deck. The second system is an overlay system in which the anodes are installed on top of the deck and then a 2 inch high density concrete overlay is piaced. Both systems were of the impressed current type using the local utility company for power. This is the second year evaluation of the project.N

Assessing the Permeability of Engineered Capillary Networks in a 3D Culture

Many pathologies are characterized by poor blood vessel growth and reduced nutrient delivery to the surrounding tissue, introducing a need for tissue engineered blood vessels. Our lab has developed a 3D co-culture method to grow interconnected networks of pericyte-invested capillaries, which can anastamose with host vasculature following implantation to restore blood flow to ischemic tissues. However, if the engineered vessels contain endothelial cells (ECs) that are misaligned or contain wide junctional gaps, they may function improperly and behave more like the pathologic vessels that nourish tumors. The purpose of this study was to test the resistance to permeability of these networks in vitro, grown with different stromal cell types, as a metric of vessel functionality. A fluorescent dextran tracer was used to visualize transport across the endothelium and the pixel intensity was quantified using a customized MATLAB algorithm. In fibroblast-EC co-cultures, the dextran tracer easily penetrated through the vessel wall and permeability was high through the first 5 days of culture, indicative of vessel immaturity. Beyond day 5, dextran accumulated at the periphery of the vessel, with very little transported across the endothelium. Quantitatively, permeability dropped from initial levels of 61% to 39% after 7 days, and to 7% after 2 weeks. When ECs were co-cultured with bone marrow-derived mesenchymal stem cells (MSCs) or adipose-derived stem cells (AdSCs), much tighter control of permeability was achieved. Relative to the EC-fibroblast co-cultures, permeabilities were reduced 41% for the EC-MSC co-cultures and 50% for the EC-AdSC co-cultures after 3 days of culture. By day 14, these permeabilities decreased by 68% and 77% over the EC-fibroblast cultures. Co-cultures containing stem cells exhibit elevated VE-cadherin levels and more prominent EC-EC junctional complexes when compared to cultures containing fibroblasts. These data suggest the stromal cell identity influences the functionality and physiologic relevance of engineered capillary networks

Guidelines for the Management of Severe Traumatic Brain Injury: 2020 Update of the Decompressive Craniectomy Recommendations

© Congress of Neurological Surgeons 2020. When the fourth edition of the Brain Trauma Foundation\u27s Guidelines for the Management of Severe Traumatic Brain Injury were finalized in late 2016, it was known that the results of the RESCUEicp (Trial of Decompressive Craniectomy for Traumatic Intracranial Hypertension) randomized controlled trial of decompressive craniectomy would be public after the guidelines were released. The guideline authors decided to proceed with publication but to update the decompressive craniectomy recommendations later in the spirit of living guidelines, whereby topics are updated more frequently, and between new editions, when important new evidence is published. The update to the decompressive craniectomy chapter presented here integrates the findings of the RESCUEicp study as well as the recently published 12-mo outcome data from the DECRA (Decompressive Craniectomy in Patients With Severe Traumatic Brain Injury) trial. Incorporation of these publications into the body of evidence led to the generation of 3 new level-IIA recommendations; a fourth previously presented level-IIA recommendation remains valid and has been restated. To increase the utility of the recommendations, we added a new section entitled Incorporating the Evidence into Practice. This summary of expert opinion provides important context and addresses key issues for practitioners, which are intended to help the clinician utilize the available evidence and these recommendations. The full guideline can be found at: https://braintrauma.org/guidelines/guidelines-for-the-management-of-severe-tbi-4th-ed#/

PhD students, interculturality, reflexivity, community and internationalisation

Interviews with a small group of doctoral students at a British university indicate that the students feel that the programme provides an environment within which they develop interculturality through reflexive engagement with the PhD community and in some cases with the participants in their research. Significant here is that they are interpretivist, constructivist qualitative researchers within a larger university community of qualitative researchers where there is a shared reflexivity that is at the core of interculturality. They also bring with them existing cultural complexity with which to engage, build on, make reflexive sense of and resolve in this experience. This complexity which they all share make it difficult to consider them differently as 'international' or 'home' students, which are revealed as inappropriately divisive labels within an intercultural community. Where there are apparent issues with English as a second or other language among some of the students, it is realised that this represents a broader struggle, shared with all students, regarding self-expression in writing. These findings demand cultural belief in whatever backgrounds the students come from. This belief impacts on how we understand internationalisation and the nature of academic knowledge and process

Performance of the G4 Xpert(R) MTB/RIF assay for the detection of Mycobacterium tuberculosis and rifampin resistance: a retrospective case-control study of analytical and clinical samples from high- and low-tuberculosis prevalence settings

BACKGROUND: The Xpert(R) MTB/RIF (Xpert) assay is a rapid PCR-based assay for the detection of Mycobacterium tuberculosis complex DNA (MTBc) and mutations associated with rifampin resistance (RIF). An updated version introduced in 2011, the G4 Xpert, included modifications to probe B and updated analytic software. METHODS: An analytical study was performed to assess Xpert detection of mutations associated with rifampin resistance in rifampin-susceptible and -resistant isolates. A clinical study was performed in which specimens from US and non-US persons suspected of tuberculosis (TB) were tested to determine Xpert performance characteristics. All specimens underwent smear microscopy, mycobacterial culture, conventional drug-susceptibility testing and Xpert testing; DNA from isolates with discordant rifampin resistance results was sequenced. RESULTS: Among 191 laboratory-prepared isolates in the analytical study, Xpert sensitivity for detection of rifampin resistance associated mutations was 97.7% and specificity was 90.8%, which increased to 99.0% after DNA sequencing analysis of the discordant samples. Of the 1,096 subjects in the four clinical studies, 49% were from the US. Overall, Xpert detected MTBc in 439 of 468 culture-positive specimens for a sensitivity of 93.8% (95% confidence interval [CI]: 91.2%-95.7%) and did not detect MTBc in 620 of 628 culture-negative specimens for a specificity of 98.7% (95% CI: 97.5%-99.4%). Sensitivity was 99.7% among smear-positive cases, and 76.1% among smear-negative cases. Non-determinate MTBc detection and false-positive RIF resistance results were low (1.2 and 0.9%, respectively). CONCLUSIONS: The updated Xpert assay retained the high sensitivity and specificity of the previous assay versions and demonstrated low rates of non-determinate and RIF resistance false positive results

Regional pressure and temperature differences across the injured human brain : comparisons between intraparenchymal and ventricular measurements

Introduction: Intraparenchymal, multimodality sensors are commonly used in the management of patients with severe traumatic brain injury (TBI). The ‘gold standard’, based on accuracy, reliability and cost for intracranial pressure (ICP) monitoring is within the cerebral ventricle (external strain gauge). There are no standards yet for intracerebral temperature monitoring and little is known of temperature differences between brain tissue and ventricle. The aim of the study therefore was to determine pressure and temperature differences at intraparenchymal and ventricular sites during five days of continuous neurominitoring. Methods: Patients with severe TBI requiring emergency surgery. Inclusion criteria: patients who required ICP monitoring were eligible for recruitment. Two intracerebral probe types were used: a) intraventricular, dual parameter sensor (measuring pressure, temperature) with inbuilt catheter for CSF drainage: b) multiparameter intraparenchymal sensor measuring pressure, temperature and oxygen partial pressure. All sensors were inserted during surgery and under aseptic conditions. Results: Seventeen patients, 12 undergoing neurosurgery (decompressive craniectomy n=8, craniotomy n=4) aged 21–78 years were studied. Agreement of measures for 9540 brain tissue-ventricular temperature ‘pairs’ and 10,291 brain tissue-ventricular pressure ‘pairs’ were determined using mixed model to compare mean temperature and pressure for longitudinal data. There was no significant overall difference for mean temperature (p=0.92) or mean pressure readings (p=0.379) between tissue and ventricular sites. With 95.8% of paired temperature readings within 2SD (−0.4 to 0.4°C) differences in temperature between brain tissue and ventricle were clinically insignificant. For pressure, 93.5% of readings pairs fell within the 2SD range (−9.4756 to 7.8112 mmHg) (Fig. 2). However, for individual patients, agreement for mean tissue-ventricular pressure differences was poor on occasions. Conclusions: There is good overall agreement between paired temperature measurements obtained from deep white matter and brain ventricle in patients with and without early neurosurgery. For paired ICP measurements, 93.5% of readings were within 2SD of mean difference. Whilst the majority of paired readings were comparable (within 10mmHg) clinically relevant tissue-ventricular dissociations were noted. Further work is required to unravel the events responsible for short intervals of pressure dissociation before tissue pressure readings can be definitively accepted as a reliable surrogate for ventricular pressure.</p