Radiographic measurements of the trachea in domestic short haired and Persian cats

Tracheal diameter can be assessed from a thoracic radiograph, with assessment of tracheal diameter in dogs based on ratios between tracheal diameter and a skeletal measurement – however reference ranges are not available for the cat. Tracheal narrowing may cause significant clinical problems, although tracheal hypoplasia in dogs may be clinically silent, and is rarely reported in cats (both mesati- and brachycephalic). The tracheal diameter and trachea:thoracic inlet and trachea:rib ratios were calculated for populations of Domestic Short Haired (DSH) (n=68) and Persian (n=40) cats. This gave reference ranges for radiographic tracheal measurements in these breeds. It is proposed that the tracheal diameter in a normal DSH cat should be 18% of the diameter of the thoracic inlet, and compared to 20% in Persian cats

Concurrent Carbon Capture and Biocementation through the Carbonic Anhydrase (CA) Activity of Microorganisms -a Review and Outlook, Environmental Processes

Biocementation, i.e., the production of biomimetic cement through the metabolic activity of microorganisms, offers exciting new prospects for various civil and environmental engineering applications. This paper presents a systematic literature review on a biocementation pathway, which uses the carbonic anhydrase (CA) activity of microorganisms that sequester CO2 to produce biocement. The aim is the future development of this technique for civil and (geo-)environmental engineering applications towards CO2-neutral or negative processes. After screening 248 potentially relevant peer-reviewed journal papers published between 2002 and 2023, 38 publications studying CA-biocementation were considered in the review. Some of these studies used pure CA enzyme rather than bacteria-produced CA. Of these studies, 7 used biocementation for self-healing concrete, 6 for CO2 sequestration, 10 for geotechnical applications, and 15 for (geo-)environmental applications. A total of 34 bacterial strains were studied, and optimal conditions for their growth and enzymatic activity were identified. The review concluded that the topic is little researched; more studies are required both in the laboratory and field (particularly long-term field experiments, which are totally lacking). No studies on the numerical modelling of CA-biocementation and the required kinetic parameters were found. The paper thus consulted the more widely researched field of CO2 sequestration using the CA-pathway, to identify other microorganisms recommended for further research and reaction kinetic parameters for numerical modelling. Finally, challenges to be addressed and future research needs were discussed

Synthesis and Utilisation of Hybrid Metal-Carbonic Anhydrase Enzyme Carrier System for Soil Biocementation

Biocementation is an emerging nature-inspired method of producing eco-friendly cement for soil stabilization. This paper used the bovine-derived carbonic anhydrase (CA) enzyme to catalyse the bioprecipitation of CaCO3 in a fine-grained soil and thus to biocement the soil. To increase the efficiency of the CA, an innovative copper–carbonic anhydrase (CA) hybrid was fabricated. This study is a proof-of-concept of the potential application of these enzyme carriers for soil bioce-mentation. The hybrid carriers are aimed to enhance the stability, recovery and reusability of the enzyme used in the biocementation process. The results showed that the fabricated copper phosphate-based inorganic hybrid was stable throughout the duration of the tests (2 months) and under a wide range of pH and temperatures. Its enzymatic activity was enhanced compared to the free CA enzyme and it was proved suitable for soil biocementation. This was further confirmed by the SEM analysis. Additionally, the treated soil with the formulated hybrid carrier showed im-proved unconfined compressive strength, especially when the carriers were implemented into the soil by mixing. The material analysis by Raman spectroscopy confirmed calcium carbonate as the primary precipitate, consistent with soil biocementation. Overall, this innovative method of de-livery of enzymes with enhanced stability and activity shows promise that, upon further devel-opment, it can be successfully used to increase the efficiency and sustainability of the biocemen-tation process

Synthesis, characterisation, and utilisation of copper nanoflower for biocementation for ground improvement applications

Microbially-induced calcium carbonate precipitation (MICP) has recently emerged as a sustainable ground improvement method. Nevertheless, the technique’s applicability in soils with narrow pore throats has been queried. To overcome these challenges, the use of enzymes (including bacterially produced enzymes) was proposed for these soils. However, the use of free enzymes entails many challenges linked predominantly to the limited enzyme supply, the poor stability of the enzyme once released into the soil, and the poor reusability of the enzyme. This paper studies the use of nano enzymes with a high biocementation efficacy for carbonic anhydrase (CA) enzyme delivery as one possible way to overcome potentially these challenges. CA enzyme was used because it has the potential to be an environmentally sustainable biocementation pathway due to its ability to sequester CO2 for biocement production. The paper presents the synthesis, characterisation, and utilisation of CA-enwrapped copper phosphate-based inorganic hybrid nanoflowers for innovative delivery and enzyme stabilisation due to the enhanced thermal and enzyme activity efficiency and due to their reusability, if recovered at the end of the treatment. The results from this study show that the bovine carbonic anhydrase enzyme enhanced the CO2 hydration reaction, resulting in a bioprecipitation reaction and the production of calcium carbonate and increased strength of treated soil with 500kPa for free CA and approximately 1000kPa for the hybrid CA-Cu. The material analysis confirmed calcite as the primary precipitate formed, which would act as a bonding agent between soil particles for ground improvement applications

The Effect of Crystallization on the Pulsations of White Dwarf Stars

We consider the pulsational properties of white dwarf star models with temperatures appropriate for the ZZ Ceti instability strip and with masses large enough that they should be substantially crystallized. Our work is motivated by the existence of a potentially crystallized DAV, BPM 37093, and the expectation that digital surveys in progress will yield many more such massive pulsators. A crystallized core makes possible a new class of oscillations, the torsional modes, although we expect these modes to couple at most weakly to any motions in the fluid and therefore to remain unobservable. The p-modes should be affected at the level of a few percent in period, but are unlikely to be present with observable amplitudes in crystallizing white dwarfs any more than they are in the other ZZ Ceti's. Most relevant to the observed light variations in white dwarfs are the g-modes. We find that the kinetic energy of these modes is effectively excluded from the crystallized cores of our models. As increasing crystallization pushes these modes farther out from the center, the mean period spacing between radial overtones increases substantially with the crystallized mass fraction. In addition, the degree and structure of mode trapping is affected. The fact that some periods are strongly affected by changes in the crystallized mass fraction while others are not suggests that we may be able to disentangle the effects of crystallization from those due to different surface layer masses.Comment: 18 pages, 5 figures, accepted on 1999 July 2 for publication in the Astrophysical Journa

Enhancing our understanding of small bowel function using modern imaging techniques

Small intestinal function is critical to digestive health and patients believe an abnormal reaction to food is responsible for many of their symptoms. Despite this, our ability to assess disturbed function in clinical practice has been limited, particularly after ingestion of the complex nutrients which make up normal food. Recent advances in both wireless capsules and magnetic resonance imaging have provided new insights. This review will briefly describe the limitations of past techniques and focus on how these newer techniques are changing our understanding, particularly of how patients’ gastrointestinal tracts respond to food

The stability of food intake between adolescence and adulthood: a 21-year follow-up

Studies of the diet of adolescents in the UK demonstrate that dietary habits known to be detrimental to health in adulthood are evident at an early age. For example, Gregory et al (2000) found 4-18 year olds in the UK to have a frequent consumption of fatty and sugary foods and low consumption of fruit and vegetables. Concerns have therefore been expressed regarding the diet of children and adolescents and the continuation of these dietary habits into adulthood (HEA, 1995; Gaziano, 1998). This study aimed to investigate the extent to which these concerns may be justified by determining the stability of food intake of a group of adolescents followed up 21 years later in adulthood. The investigation involved 202 individuals from whom dietary data were collected in 1979-80 (mean age 11.6 years) (Hackett et al. 1984) and again in 2000-1 (mean age 32.5 years). Dietary data were collected at both time-points using two 3 d estimated food diaries followed by an interview to determine portion sizes using the method considered most appropriate at the time, i.e. calibrated food models in 1979-80 and a photographic food atlas (Nelson et al. 1997) in 2000-1. Foods consumed were allocated to one, or a combination of, the five food groups of the ‘Balance of Good Health’ food selection guide (HEA, 1994) according to Gatenby et al. (1995). The weight of food eaten from each of the five food groups was calculated (percentage of total weight of food consumed) and Pearson correlation coefficients generated to provide an estimate of the stability of food intake. The HEA guide advises that a balanced diet should consist of around 33% fruit and vegetables, 33% bread, other cereals and potatoes, 8% foods containing fat and/or sugar, 12% meat, fish and alternatives and 15% milk and dairy products (Gatenby et al. 1995). A shift in the group’s food intake towards the recommendations had occurred with age, most notably with a decrease in foods containing fat and/or sugar and an increase in fruit and vegetables. Nevertheless, at both ages, intakes of foods containing fat and/or sugar, meat, fish and alternatives were higher, and fruit, vegetables, bread, other cereals and potatoes lower than currently recommended. In addition, although there was significant evidence of tracking of relative intake of bread, cereals and potatoes (P<0.01), fruit and vegetables (P<0.01), and meat, fish and alternatives (P=0.02) between 11.6 and 32.5 years, the correlations were not strong. In conclusion, food intake patterns had changed considerably from early adolescence through to adulthood in a direction more in line with the current recommendations. The predictive value of an adolescent’s food intake of their intake in adulthood was found to be significant, but not strong. Further investigations will consider the extent to which this is influenced by factors such as social class, gender and educational level, as well as assessing tracking in terms of relative nutrient intakes

Innovative methods of ground improvement for railway embankment Peat Fens foundation soil

The aim of this research was to assess the feasibility of biocementing a problematic foundation soil of railway embankments from Peat Fens in East Anglia, UK. Biocementation of soil is an emerging, novel ground improvement technique. It has recently attracted the interest of researchers worldwide because it has been proposed as potentially environmentally superior to chemical grouts and other common soil stabilisers e.g. cement or lime (linked to high CO2 11 emissions). In this study we screened and isolated non-pathogenic indigenous ureolytic microbial candidates with potential for biocementation from samples originating from Peat Fens in East Anglia, UK. Four strains were selected as the most suitable candidates, based on their growth rate and their viability in a wide range of temperatures, pH and soil moisture contents corresponding to typical seasonal field conditions. After a number of Unconfined Compressive Strength (UCS) tests, one strain (Bacillus licheniformis) was selected as the most promising for this soil treatment and used for further study. Two different methods of implementation of the treatments were considered, namely pressure flow soil column and electrokinetic injection. The UCS results supported by CaCO3 measurements as well as microstructural SEM-EDS analysis proved that biocementation did occur for both implementation methods and for a number of treatment combinations. Ongoing work on optimisation of treatments and implementation methods is carried out towards the upscaling of the techniques for in situ implementation which is planned for the next stage of the research

Deep ROSAT Surveys & the contribution of AGNs to the soft X-ray background

The ROSAT Deep Surveys in the Lockman Hole have revealed that AGNs are the main contributors (~75%) to the soft X-ray background in the 1–2 keV band. Using new optical/infrared and radio observations we have obtained a nearly complete identification (93%) of the 91 X-ray sources down to a limiting flux of 1.2·10^(–15) erg cm^(–2) s^(–1) in the 0.5–2.0 keV band. We present the optical colors and the emission line properties of our AGNs in comparison with other X-ray selected AGN samples. Furthermore we discuss the fraction of red AGNs found in the ROSAT Deep Surveys. From the ROSAT Deep Surveys we see no evidence for a new class of X-ray bright galaxies, which significantly contributes to the soft X-ray background

Biocementation mediated by native Carbonic Anhydrase-producing microbes.

This study investigated the feasibility of biocementing a fine-grained foundation soil from the East Anglia railway network via the carbonic anhydrase (CA) pathway. This pathway is a promising way of improving the mechanical properties of soils by biocementation while sequestering CO2 during the process. To achieve the aim of this research, forty CA-producing bacterial isolates from soil layers below a railway embankment in East Anglia, UK, were screened and selected using a qualitative CA activity assay. Three of these bacteria expressed high and stable CA enzyme activity and were further characterised by their morphological, molecular, and enzyme profile characteristics. Bioaugmentation was then employed to biocement the soil from the site using the native CA-producing bacteria isolated from the soil. The unconfined compressive strength and calcite content of the treated soil were determined. Preliminary results showed a substantial increase in soil unconfined compressive strength upon biocementation treatment. Although further geotechnical testing is the subject of future work, the unconfined compressive strength and calcite content results obtained so far proved biocementation of the fine-grained soil and showed promise that the CA biocementation route can be further developed as a successful and environmentally friendly soil stabilization technique, with the added advantage of sequestering CO2 from the atmosphere or using captured waste CO2, during the biocementation process