272 research outputs found
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The Ca2+ transient as a feedback sensor controlling cardiomyocyte ionic conductances in mouse populations.
Conductances of ion channels and transporters controlling cardiac excitation may vary in a population of subjects with different cardiac gene expression patterns. However, the amount of variability and its origin are not quantitatively known. We propose a new conceptual approach to predict this variability that consists of finding combinations of conductances generating a normal intracellular Ca2+ transient without any constraint on the action potential. Furthermore, we validate experimentally its predictions using the Hybrid Mouse Diversity Panel, a model system of genetically diverse mouse strains that allows us to quantify inter-subject versus intra-subject variability. The method predicts that conductances of inward Ca2+ and outward K+ currents compensate each other to generate a normal Ca2+ transient in good quantitative agreement with current measurements in ventricular myocytes from hearts of different isogenic strains. Our results suggest that a feedback mechanism sensing the aggregate Ca2+ transient of the heart suffices to regulate ionic conductances
Femoral non-union above a fused knee: Successful treatment with exchange nailing and intramedullary delivery of bone morphogenetic protein
Bone healing is a complex and well-orchestrated physiological process, in which bone repairs and regenerates regaining its original biomechanical and biochemical properties. It is estimated that 5 to 10% of all fractures are complicated by delayed union or non-union. Progression to non-union is thought to be multifactorial, even though the exact biological sequence remains obscure.
Treatment should aim to addressing deficiencies in both the mechanical and biological components, along with eliminating co-factors that could negatively affect the locally induced fracture healing response.
We report a case of a 78-year-old patient who presented with a distal femoral non-union above a previously fused knee, which was successfully managed with exchange nailing and intramedullary delivery of recombinant human bone morphogenetic protein-7 (rhBMP-7)
Efficiency assessment for a small heliostat solar concentration plant
Summary In this paper, a small non-imaging focusing heliostat is presented, and an analytical model for assessing its performance is described. The main novelty of the system lies in the tracking mechanism and the mirror mount, which are based on off-the-shelf components and allow a good trade-off between accuracy and costs. The concentrator mirrors are moved by this two-axis tracking machinery to reflect the sun's rays onto a fixed target, the dimensions of which can be varied to suit the user's needs. A prototype plant to be located in central Italy was designed and simulated with a ray-tracing algorithm, and it comprises 90 heliostats for a total reflective area of 7.5 m2. The reflected solar rays are tracked taking the mechanical positioning errors of the tracking system into account. The total flux of radiation energy hitting the target was determined, and intensity distribution maps were drawn. Simulations showed that the system's optical efficiency can exceed 90% in summer, despite the tracking errors, mainly because of the smaller distance between the heliostats and the receiver. The solar concentration ratio over a receiver of 250 mm in diameter reached 80 suns with a very good uniformity. Over a 400-mm receiver, the concentrated radiation was less uniform, and the solar concentration ratio reached 50 suns, with a higher optical efficiency and collected solar radiation. The present concentration ratio is still suitable for many applications ranging from the electric power production, industrial process heat, and solar cooling. Copyright © 2014 John Wiley & Sons, Ltd
Turning agricultural wastes into biomaterials: Assessing the sustainability of scenarios of circular valorization of corn cob in a life-cycle perspective
Circular economy plays a key role in increasing the sustainability of the agricultural sector, given the countless possibilities of transforming crop residues and recycling precious resources. The maize cultivation process produces a significant amount of residual organic materials, commonly left on the field, as a soil conditioner and source of nutrients even if some parts, such as the cob, play a minor role in these actions. The solutions for the valorization of this remnant depend on economic and environmental factors and the evaluation of the environmental performances of the processes in a life-cycle perspective is important to compare the overall sustainability of the valorization alternatives, maximizing their environmental added value. This work reports the results of Life Cycle Analysis, from cradle-to-gate of corn cob valorized as a raw material in two scenarios: corn cob pellet and corn cob abrasive grits to use as blasting or finishing media. A comparative study has been performed with two products available on the market and with the same functions. The results show that cob-based products have lower impact than those currently used. The work provides indication for evaluating the benefits of turning agricultural wastes in natural-based materials and intends to promote circular economy processes in agriculture production
Behavior and welfare of undocked heavy pigs raised in buildings with different ventilation systems
The present study aimed to evaluate animal welfare of pigs from the same farm, raised with two ventilation systems. The study involved 60 pens of fattening pigs, raised in two buildings: one naturally ventilated (NV) and the other mechanically ventilated (MV). Pigs were assessed on three observation days: at 40 kg (T1), 100 kg (T2), and 160 kg (T3) of live weight. Animal-based measures were used such as qualitative behavioral analysis (QBA), behavioral measures (BMs), and lesion and health measures (LHMs). Housing conditions (HCs) measured at each observation day were the number of pigs per pen, space allowance, temperature, light, and CO2. The association study was performed using a general linear model and analysis of variance. Ventilation effect was analyzed by performing computational fluid dynamics. Results showed that overall pigs raised in the MV were in a more positive affective state. Despite that, with hot temperatures, the higher oc-currence of pig soiling indicated heat stress in pigs and consequent welfare impairment. The higher frequency of pigs showing dog sitting behavior at T2 and T3 suggest welfare worsening in the last phases of fattening. The study concludes that ventilation system influences animal behavior and overall animal welfare, especially during the warmer season
Photochemical reaction paths of cis-dienes studied with RASSCF: the changing balance between ionic and covalent excited states
International audienc
Methodology for sensor calibration in agro-industrial facilities
The rising need of precision in several sectors, agriculture included, brings to the development of new monitoring systems customised for the specific application. These systems often take advantages of probes offered by the market, however, the integration between market probes and home-built systems, requires tests to validate the recorded measurements.This paper provides a methodology to perform a calibration procedure when the probes fail the validation test.The results show the comparison of the measurements collected by investigated sensors and reference sensor coupled with the application of simple correlation methods can bring to an improvement of the sensor precision as far as to pass the validation test
Microventilation system improves the ageing conditions in existent wine cellars
Background and Aims: The importance of indoor environmental conditions in a cellar is well known and continuously investigated. The process of wine ageing consists of several steps, during which temperature (T) and relative humidity (RH) play a fundamental role as the quality of the final product is strongly related to stable and suitable environmental conditions. Critical factors, such as mould growth or wine evaporation, have emerged when ventilation has proved to be insufficient or poorly designed. The limitation of stagnant areas and the homogeneity inT and RH provide for proper wine conservation; however, unwanted local conditions can occur in the zones with insufficient air exchange. Methods and Results: Considering these aspects, a controlled microventilation and monitoring system was installed in a case study cellar, and T and RH were monitored for 1 year. The data have been analysed to investigate criticalities of the environmental conditions. The ventilation was activated in specific critical conditions to increase the homogeneity of the T and RH in the critical zones. The results show that the microventilation system improves the homogeneity of both T and RH without affecting the average values. Conclusions: The study demonstrated the efficacy of the system and indicated possible modifications to improve system performance. Significance of the Study: The system proved to be a useful tool for both improving the environmental conditions and providing useful information to the winemakers about the ageing conditions
A Modified Rabbit Ulna Defect Model for Evaluating Periosteal Substitutes in Bone Engineering: A Pilot Study
The present work defines a modified critical size rabbit ulna defect model for bone regeneration in which a non-resorbable barrier membrane was used to separate the radius from
the ulna to create a valid model for evaluation of tissue-engineered periosteal substitutes.
Eight rabbits divided into two groups were used. Critical defects (15 mm) were made
in the ulna completely eliminating periosteum. For group I, defects were filled with a
nanohydroxyapatite poly(ester urethane) scaffold soaked in PBS and left as such (group
Ia) or wrapped with a tissue-engineered periosteal substitute (group Ib). For group II, an
expanded-polytetrafluoroethylene (e-PTFE) (GORE-TEX\uae) membrane was inserted around
the radius then the defects received either scaffold alone (group IIa) or scaffold wrapped
with periosteal substitute (group IIb). Animals were euthanized after 12\u201316 weeks, and
bone regeneration was evaluated by radiography, computed microtomography (\ub5CT), and
histology. In the first group, we observed formation of radio-ulnar synostosis irrespective
of the treatment. This was completely eliminated upon placement of the e-PTFE (GORETEX\uae) membrane in the second group of animals. In conclusion, modification of the model
using a non-resorbable e-PTFE membrane to isolate the ulna from the radius was a valuable
addition allowing for objective evaluation of the tissue-engineered periosteal substitut
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