Long Term Performance Of Passive House Buildings

Long term experience with Passive House buildings is illustrated with two early large scale projects, a school and an office building located in Germany. Those were monitored in lump energy performance (school, commissioned 2004) and great detail (office, commissioned 2002) respectively. Moreover, they give an indication of the characteristics of such buildings subject to changes in usage intensity. Both buildings generally performed as expected with the school facing occasional overheating in the summer due to inflexible shading controls. Following an extension in schooling hours the addition of a canteen was required and the ventilation system was adapted to the changed usage. Nevertheless the building’s user comfort and energy performance remain high,despite exceeding the Passive House primary energy target slightly due to increased electricity consumption. The office likewise meets the calculated efficiency in operation. The ground coupled cooling worked well despite greatly increased internal heat gains due to unexpected usage. This extra heat input did not, however, exhaust the geothermal (passive) cooling capacity for the future. Thermal comfort proved near optimal at all times, despite a very simple control regime of the one-circuit concrete core activation system for heating and cooling. In the last section air tightness design and measurement experience in the UK and particularly the question of long-term stability of the airtight building envelope is assessed. It was found that measurement results are not only repeatable in relatively short intervals such as a few months. The data available suggests stability of the airtight envelope over many years. Attention is required as regards the leakage of party walls of terraced buildings which need to be integrated in the overall airtightness concept. A high permeability of party walls in terraced buildings with a common airtight envelope presents a challenge for measuring air tightness. Long-term series of airtightness measurements exist for the Kranichstein House in Darmstadt/Germany and prove the stability of the chosen airtightness concept. Moreover, results for 17 early Passive House buildings in Germany in eight locations and various construction types revisited in 2001 (1.4 to 10 years after the initial airtightness test) suggest stability of air tightness values over time. Great advances have since been made in materials and methods available and the general understanding in the industry. This is supported by a large sample of 2934 Passive House projects of varied construction materials, locations, sizes and usages that yielded an average air tightness test result as low as n50 = 0.41 h-1

Investigation of photoneutron reactions close to and above the neutron emission threshold in the rare earth region

We have investigated the photoneutron cross section of the isotopes $^{148,150}$Nd, $^{154}$Sm, and $^{154,160}$Gd close to the neutron emission threshold in photoactivation experiments at the Darmstadt superconducting electron linear accelerator S-DALINAC. Naturally composed targets were activated with a high-intensity bremsstrahlung beam at various energies and the reaction yields have been determined by measuring the activity of the produced radioactive isotopes with HPGe detectors. The results are compared to two different statistical model calculations.Comment: Accepted for publication in Physical Review

Determination of 141Pr(alpha,n)144Pm cross sections at energies of relevance for the astrophysical p-process using the gamma-gamma coincidence method

The reaction 141Pr(alpha,n)144Pm was investigated between E_alpha=11 MeV and 15 MeV with the activation method using the gamma-gamma coincidence method with a segmented clover-type high-purity Germanium (HPGe) detector. Measurements with four other HPGe detectors were additionally made. The comparison proves that the gamma-gamma coincidence method is an excellent tool to investigate cross sections down to the microbarn range. The (alpha,n) reaction at low energy is especially suited to test alpha+nucleus optical-model potentials for application in the astrophysical p-process. The experimentally determined cross sections were compared to Hauser-Feshbach statistical model calculations using different optical potentials and generally an unsatisfactory reproduction of the data was found. A local potential was constructed to improve the description of the data. The consequences of applying the same potential to calculate astrophysical (gamma,alpha) rates for 145Pm and 148Gd were explored. In summary, the data and further results underline the problems in global predictions of alpha+nucleus optical potentials at astrophysically relevant energies.Comment: 13 pages, 9 figures, accepted in Phys. Rev.

Therapy-refractory Panton Valentine Leukocidin-positive community-acquired methicillin-sensitive Staphylococcus aureus sepsis with progressive metastatic soft tissue infection: a case report

We report a case of fulminant multiple organ failure including the Acute Respiratory Distress Syndrome (ARDS), haemodynamic, and renal failure due to community-acquired methicillin-sensitive Panton Valentine Leukocidin (PVL) positive spa-type 284 (ST121) Staphylococcus aureus septic shock. The patient's first clinical symptom was necrotizing pneumonia. Despite organism-sensitive triple antibiotic therapy with linezolid, imipenem and clindamycin from the first day of treatment, progressive abscess formation in multiple skeletal muscles was observed. As a result, repeated surgical interventions became necessary. Due to progressive soft tissue infection, the anti-microbial therapy was changed to a combination of clindamycin and daptomycin. Continued surgical and antimicrobial therapy finally led to a stabilisation of the patients' condition. The clinical course of our patient underlines the existence of a "PVL-syndrome" which is independent of in vitro Staphylococcus aureus susceptibility. The PVL-syndrome should not only be considered in patients with soft tissue or bone infection, but also in patients with pneumonia. Such a condition, which may easily be mistaken for uncomplicated pneumonia, should be treated early, aggressively and over a long period of time in order to avoid relapsing infection

Docking and molecular dynamics simulations of the ternary complex nisin2:lipid II

Lanthionine antibiotics are an important class of naturally-occurring antimicrobial peptides. The best-known, nisin, is a commercial food preservative. However, structural and mechanistic details on nisin/lipid II membrane complexes are currently lacking. Recently, we have developed empirical force-field parameters to model lantibiotics. Docking and molecular dynamics (MD) simulations have been used to study the nisin2:lipid II complex in bacterial membranes, which has been put forward as the building block of nisin/lipid II binary membrane pores. A Ile1Trp mutation of the N-terminus of nisin has been modelled and docked onto lipid II models; the computed binding affinity increased compared to wildtype. Wild-type nisin was also docked onto three different lipid II structures and a stable 2:1 nisin:lipid II complex formed. This complex was inserted into a membrane. Six independent MD simulations revealed key interactions in the complex, specifically the N terminal engagement of nisin with lipid II at the pyrophosphate and C-terminus of the pentapeptide chain. Nisin2 inserts into the membrane and we propose this is the first step in pore formation, mediated by the nisin N-terminus–lipid II pentapeptide hydrogen bond. The lipid II undecaprenyl chain adopted different conformations in the presence of nisin, which may also have implications for pore formation

Identification of InuR, a new Zn(II)2Cys6 transcriptional activator involved in the regulation of inulinolytic genes in Aspergillus niger

The expression of inulinolytic genes in Aspergillus niger is co-regulated and induced by inulin and sucrose. We have identified a positive acting transcription factor InuR, which is required for the induced expression of inulinolytic genes. InuR is a member of the fungal specific class of transcription factors of the Zn(II)2Cys6 type. Involvement of InuR in inulin and sucrose metabolism was suspected because of the clustering of inuR gene with sucB, which encodes an intracellular invertase with transfructosylation activity and a putative sugar transporter encoding gene (An15g00310). Deletion of the inuR gene resulted in a strain displaying a severe reduction in growth on inulin and sucrose medium. Northern analysis revealed that expression of inulinolytic and sucrolytic genes, e.g., inuE, inuA, sucA, as well as the putative sugar transporter gene (An15g00310) is dependent on InuR. Genome-wide expression analysis revealed, three additional putative sugar transporters encoding genes (An15g04060, An15g03940 and An17g01710), which were strongly induced by sucrose in an InuR dependent way. In silico analysis of the promoter sequences of strongly InuR regulated genes suggests that InuR might bind as dimer to two CGG triplets, which are separated by eight nucleotides

Fungal enzyme sets for plant polysaccharide degradation

Enzymatic degradation of plant polysaccharides has many industrial applications, such as within the paper, food, and feed industry and for sustainable production of fuels and chemicals. Cellulose, hemicelluloses, and pectins are the main components of plant cell wall polysaccharides. These polysaccharides are often tightly packed, contain many different sugar residues, and are branched with a diversity of structures. To enable efficient degradation of these polysaccharides, fungi produce an extensive set of carbohydrate-active enzymes. The variety of the enzyme set differs between fungi and often corresponds to the requirements of its habitat. Carbohydrate-active enzymes can be organized in different families based on the amino acid sequence of the structurally related catalytic modules. Fungal enzymes involved in plant polysaccharide degradation are assigned to at least 35 glycoside hydrolase families, three carbohydrate esterase families and six polysaccharide lyase families. This mini-review will discuss the enzymes needed for complete degradation of plant polysaccharides and will give an overview of the latest developments concerning fungal carbohydrate-active enzymes and their corresponding families