Efficacy of ceftazidime-avibactam in a rat intra-abdominal abscess model against a ceftazidime- and meropenem-resistant isolate of Klebsiella pneumoniae carrying blaKPC-2

Efficacies of ceftazidime-avibactam (4:1 w/w) and ceftazidime were tested against ceftazidime-susceptible (blaKPC-2-negative), and meropenem- and ceftazidime-resistant (blaKPC-2-positive), Klebsiella pneumoniae in a 52-h, multiple dose, abdominal abscess model in the rat. Efficacies corresponded to minimum inhibitory concentrations (MICs) measured in vitro and were consistent with drug exposures modelled from pharmacokinetics in infected animals. The ceftazidime, ceftazidime-avibactam and meropenem control treatments were effective in the rat abscess model against the susceptible strain, whereas only ceftazidime-avibactam was effective against K. pneumoniae harbouring blaKPC-2

Design of a water heating tank based on utilization of the waste heat energy of refrigerants

W artykule przedstawiono propozycję konstrukcji naczynia do ogrzewania wody do celów socjalnych. Jako czynnik grzewczy w zaprojektowanym systemie wykorzystano ciepło z obiegu wtórnego urządzeń chłodniczych. Uzyskane wyniki na urządzeniu prototypowym (rys. 4) pozwalają stwierdzić, że istnieje możliwość warstwowego ogrzewania cieczy wewnątrz naczynia. Dzieje się to wówczas, jeśli do miejsca wymiany ciepła dostarczana jest stale chłodna woda. Zaprojektowana konstrukcja umożliwia wykorzystanie niskotemperaturowych źródeł ciepła z obiegów chłodzących do ogrzewania wody, eliminując niebezpieczeństwo przeniknięcia mediów.In the contribution is submitted proposal of the vessel construction for water for industrial use. For heating is being used the secondary heat from the cooling system. More frequent utilization of this energy is limited of present by two facts: 1. The cooling devices contain toxic charge and therefore the pipeline for cooling medium passing through must not be in direct contact with the heated water for hygiene and safety reasons. 2. Sufficient thermal difference for effective heat sharing is possible only when the cool water is supplied to the place of heating. The suggested construction solves both these problems. The primary pipeline with ammonia is located on the container outer side into other heat-carrying protective medium. The inner arrangement provides the isothermal water stratification in container. In to the container is located the insert from non-conductive material with outer dimension smaller than the inner diameter of container. This enables formation of the slot filled by the heated water. Between the hot water in the slot and cold water inside the vessel creates the pressure difference, heated water rises into the upper part of the container and cold water is sucked into the slot from the bottom. Within the heating almost whole container volume is therefore reached steady thermal gradient between the heating and heated medium and maximum effectiveness of the heat sharing. After verification of the suggested construction the device prototype is manufactured enabling monitoring of the temperature course in various parts of the device in dependence on time. The temperature layout inside the container was monitored by five thermal sensors located in the vessel centre line in distance of 150 mm (Fig. 3). From the measuring results is evident the heated water stratification inside the vessel. To the heating point is continuously supplied water of initial temperature (Fig. 4) for 15 minutes. Nevertheless, from the measured temperature resulted that the cooling medium secondary heat is not utilized sufficiently. The maximum output of the device at the heating beginning is almost 5 kW. This it will be necessary to extend the heat-exchanging surface of the exchanger or to adapt the slot shape along the vessel periphery to reach lower flow rate of the heated water. The described device will enable after the suggested adaptation the effective utilization of the secondary heat of the cooling medium without risk of its penetration into the heated water

Use of evaporation cooling of stable air in the given territory

Przy ocenie, czy efektywne jest wykorzystanie chłodzenia powietrza w stajni przez parowanie w danym rejonie, należy znać szczegółowe długoterminowe dane meteorologiczne. Jednakże czasem potrzebne dane są z różnych powodów niedostępne. W artykule jest wypróbowana metoda generowania sztucznego szeregu dziennych maksymalnych temperatur powietrza z miesięcznych średnich. Przy odchyleniu standardowym σ (ºC), stwierdzonym przy pomocy statystycznej analizy dostępnych danych, i średniej spodziewanej temperaturze toc (ºC), określonej przez wyznaczenie sinusoidy przez dwanaście, ewent. dwie miesięczne średnie maksymalnych temperatur, szukana maksymalna dzienna temperatura powietrza w dzień (d) jest określona wzorem 2 e(d) oc(d) e(d 1) oc(d) (d) t = t + 0,65 ⋅ (t − t ) + σ √ n ⋅ 1− 0,65 − (ºC), gdzie n (-) jest przypadkową liczbą z szeregu, który ma normalny rozkład, średnią wartość 0 i odchylenie standardowe 1. Tą metodą był generowany trzydziestoletni szereg wartości dla stacji klimatologicznej Mošnov (49,69º s.š., 18,12º v.d., 251 m n.p.m.). Obliczone wartości są porównane z wartościami zmierzonymi. Bardziej odpowiedni jest szereg danych generowany z 12 miesięcznych średnich, chociaż szereg danych z 2 średnich wystarczyłby do oceny efektywności chłodzenia. Z wyników modelowania rozwoju klimatu wynika, że około roku 2050 maksymalna temperatura powietrza w czerwcu, ewent. lipcu, ewent. w sierpniu podwyższy się o 1,8 K, ewent. 2,3 K, ewent. 3,2 K przy spełnieniu pesymistycznego scenariusza wzrostu emisji gazów cieplarnianych i o 0,7 K, ewent. 0,8 K, ewent. 1,2 K przy spełnieniu optymistycznego scenariusza. Na podstawie tych wartości stworzono szeregi danych dla okresu około roku 2050. Stwierdzono, że liczba dni, kiedy maksymalna dzienna temperatura powietrza będzie przekraczać 27ºC, może się w miesiącach letnich zwiększyć nawet dwukrotnie. Jeżeli zastosowane jest chłodzenie przez parowanie z 80% wydajnością adiabatyczną i maksymalnym nawilżeniem 75%, ewent. 80%, można wysokie temperatury powietrza wyeliminować. Z 92 dni w miesiącach letnich zainstalowane urządzenie do chłodzenia przez parowanie przy temperaturze rozruchu 26 ºC, ewent. 24 ºC byłoby w danym rejonie eksploatowane przez 25,2 dnia, ewent. 41,8 dnia w obecnym czasie, 32,2 dnia, ewent. 49,5 dnia w przyszłości przy optymistycznym wariancie rozwoju i 45,6 dnia, ewent. 61,9 dnia przy spełnieniu pesymistycznego scenariusza. Ilość wody, która powinna być wyparowana przez urządzenie do powietrza wentylacyjnego w celu osiągnięcia wymaganych zmian, może wzrosnąć z obecnej wartości 5,4 g∙m-3 aż do 6,3 g∙m-3 w okresie przyszłym. Wyniki można wykorzystać przy projektowaniu efektywnego urządzenia chłodzącego w stajniach na danym terytorium.When assessing whether it is effective to use evaporation cooling of air in a stable in a particular area, it is essential to have available long-term meteorological data. However, sometimes such data is for various reasons not available. This paper tests a method of generating an artificial series of daily maximum air temperatures from monthly averages. With standard deviation σ (ºC) determined from a statistical analysis of available data and a median expected temperature toc (ºC) obtained from fitting a sine curve through twelve and two monthly average maximum temperatures, respectively, the sought maximum daily air temperature in day (d) is determined from the function 2 e(d) oc(d) e(d 1) oc(d) (d) t = t + 0.65⋅ (t − t ) + σ √ n ⋅ 1− 0.65 − (ºC), where n (-) is a random number from a series which has a normal distribution, median value 0 and standard deviation 1. Using this method, a thirty-year series of values was generated for the Mošnov Weather Station (longitude 49.69º N, latitude 18.12º E, elevation 251 m above mean sea level). The computed values are compared with measured values. The series generated from 12 monthly averages gave better results, although the series from 2 averages would do the job for assessing cooling efficiency. Results of a climatic development model show that around year 2050 the maximum air temperature in June, July and August will increase by 1.8 K, 2.3 K and 3.2 K, respectively, assuming a pessimistic scenario of the growth in greenhouse gas emissions, or by 0.7 K, 0.8 K and 1.2 K, respectively, assuming an optimistic scenario. Based on these values, a series of data was generated for the period around year 2050. It shows that the number of days on which the maximum air temperature will exceed 27ºC in summer months may as much as double. If evaporation cooling is used with 80% adiabatic efficiency and maximum humidification 75% or 80%, the high air temperatures can be eliminated. Of the 92 days of summer months, installation of evaporation cooling equipment with starting temperature 26ºC and 24ºC, respectively, would in the modelled area run at present 25.2 days and 41.8 days, respectively, and in the future 32.2 days and 49.5 days at the optimistic development variant, and 45.6 days and 61.9 days, respectively, allowing for the pessimistic scenario. Quantity of water which the equipment must be able to evaporate into the ventilation air in order to achieve the desirable effect can increase from the present value of 5.4 g/m3 to as much as 6.3 g/m3 in the future period. The results can be used when designing efficient cooling equipment in stables in the given territory

Praktyczne doświadczeniab z adiabatycznym chłodzeniem pomieszczeń chlewni za pomocą systemów zamgławiania

Heat stress of domestic animals has the increasing influence on the farming economy in Central Europe. It is not caused only by global warming. Substantial share in this situation has the introduction of new races of animals of higher productivity. On the other hand, breeding of the highly productive animals has a negative influence on moisture and heat increase. These problems can be solved by using direct adiabatic cooling system which is used especially in poultry production nowadays. An effort was made to use this technology for pig breeds too. The paper summarises the results from the observation focused on the comparison of cooled and non-cooled stable for pig breeding. The installation of this cooling system is one of the first example in pig houses in the Czech Republic. The decrease of air temperature by about 2.5-3 K was reached by means of evaporative cooling. However, it should be said, that the system was not adjusted to optimal parameters during the experiment, yet. We can expect the temperature decrease of about 5.5-6 K after the optimal adjustment.Stres termiczny zwierząt ma rosnące znaczenie dla produkcji zwierzęcej i jej ekonomiki w krajach Europy Centralnej. Wprowadzanie do produkcji nowych ras zwierząt o wyższej produktywności powoduje wzrost wilgotności i temperatury powietrza w budynkach, co jest przyczyną stresu u zwierząt. Ten problem może być rozwiązany przez chłodzenie adiabatyczne, które jest stosowane szczególnie w produkcji drobiarskiej. Istnieje potrzeba zastosowania tej technologii w produkcji trzody chlewnej. Artykuł prezentuje dane porównawcze chlewni chłodzonych i niechłodzonych. Instalacja takiego systemu chłodzenia należy do pierwszych w Czechach. Dzięki chłodzeniu przez odparowanie uzyskano obniżenie temperatury powietrza o 2,5-3 K. Należy stwierdzić, że system nie był optymalnie skonfigurowany. Po jego usprawnieniu można oczekiwać obniżenia temperatury powietrza o 5,5-6 K

Energy sorrel - an alternative fuel for rural areas

The research is focused on energy sorrel as a fuel for local low-power heating systems with output up to 100 kW. Sorrel is perennial plant surviving in its location nearly 18 years which is very good from the point of crop expenses. It is a robust plant with height of about 2 m in second year of plantation. Dry phytomass is energetically rich fuel with total heating value 17.5 – 18.0 MJ.kg-1 at the average yield of 10 tons per hectare. An experimental combustion of pure sorrel and its blends were done with boiler VERNER A25 – a hot water boiler for pellets. 11 different sorrel fuels consisting of 5 primary kinds were tested during the experiment: sorrel (Rumex tianshanicus x Rumex patientia), Phalaroides arundinacea, Canabis sativa, pine-bark, sorrel (Rumex tianshanicus x Rumex patientia), brown coal. Based on collected data it is possible to obtain an overview of these fuels and their emission properties. Satisfactory values of CO concentration are possible to gain partly by choosing appropriate combustion device and its settings and partly by mixing with other types of fuel. In the case of sorrel the combination of both has been shown very useful. It is very hard to combust sorrel only, and its testing proves unsatisfactory results. But if we combust blend of sorrel and canary grass 1:1 in the same device, the results are somewhat better. The best results can be reached if we burn this blend in more suitable device. By this way it is even possible to fulfil the emission limits. However, if we burn only pure sorrel in another burner, the emissions are very dissatisfactory again. Another possibility of how to burn sorrel effectively is to combine it with brow coal. On the basis of received results, fuel containing 10 to 20 % of coal can be recommended. From point of view of ash properties pure sorrel appears a problematic fuel. During our experiment ash accumulation in combustion chamber was observed. Unburnt fuel blocked air intakes which caused burning deterioration and increase of CO emissions. All above mentioned facts indicate that sorrel burning is possible if we fulfil all demands required for this fuel. Combustion of pure sorrel in any device without special settings means in many cases non effective use of fuel and bad emissions

Analysis of the influence of values and the difference of inlet temperature on thermal and exergy efficiency of the plate heat exchanger

W publikacji przeprowadzono analizę oddziaływania parametrów termicznych na egzergię strumienia strat cieplnych, egzergetyczną i cieplną sprawność płytowego rekuperatora powietrze – powietrze przy stałych objętościowych strumieniach ogrzewanego i chłodzonego powietrza. Wyniki badań i ich analiza potwierdziły zależności między egzergią strumieni strat cieplnych a wartościami temperatur zasilania, wzrostem wykorzystania ciepła z ochładzanego powietrza i spadkiem przenikania ciepła z ochładzanego do ogrzewanego powietrza wraz ze wzrostem różnicy temperatur na zasilaniu. Potwierdzono również zależność między cieplną a całkowitą energetyczną sprawnością

Heat recuperation from exhaust air in a sports hall with swimming pool

This paper deals with the determination of several efficiency types of a cross-current recovery exchanger which is a part of the air venting system in the swimming pool hall on the premises of the Czech University of Life Sciences (CULS) in Prague. The product is a cross-current plate exchanger with a heat-exchanging surface of antirust aluminium. According to the manufacturer, the exchanger is fit for temperatures common in air ventilation systems. The air is forced in by fans at a flow quantity of 16,000 m3, maximum speed 2000 rpm, electric motor output 7.5 kW, filters for the air coming from the outside – grade G4, pressure loss from 42 to 200 Pa, filters for the air coming from the inside – grade G3, pressure loss from 46 to 200 Pa. The results presented are derived from in-process measurements taken on 31 January 2007 and 7 February 2007, from 9.15 to 11.30 on both days. Air temperature and air humidity were measured with 9636-51B-type sensors by Ahlborn, connected to the AHLBORN ALMEMO 5990-2 centre. These sensors were placed into each of the four input/output channels, very close to the exchanger itself (Fig. 2). The data measured were saved in the centre memory every minute. Figures 3, 4, 5 and 6 show the temperature and humidity curves at the exchanger inlets and outlets on measurement days as well as outside air temperature (te) and outside air relative humidity (φe) captured by the met station on the CULS premises. Table 2 shows efficiency ranges calculated according to relations (1), (3), (4), (5), and (6) for air parameters ascertained at exchanger inlets and outlets on 31 January and 7 February 2007 and the calculated flow rates (Table 1). The difference between the outside temperature te and outside humidity φe values taken by the met station and the temperature te1 and humidity φe1 values measured at the recuperator inlet can be explained as resulting from the air being drawn in from the premises affected by the building and 8-m air piping situated in the building’s interior. Heat transmission to the surrounding air occurs despite the mineral wool heat insulation applied to the air piping. The slight increase of thermal efficiency observed on 7 February 2007 resulted from throttling down the recuperator feed air inlet flaps. Reducing the heated air discharge volume (see Table 1) resulted in a greater temperature difference te2 – te1. Energetic efficiency η is lower than thermal efficiency ηt because equation 3 takes into account the effect of condensed vapours in the cooled waste air. According to the manufacturers, the efficiency of top-class exchangers exceeds 70 %. This value might suggest that almost all the air energy available in the given space is utilised. Closer examination reveals that what is presented is thermal efficiency, which is always higher than other kinds of efficiency (see Table 2). Low exergetic efficiency is a sign that there still is a potential in terms of transmission of recovered air utilised energy (exergy)

Feasibility of using heat-recovery exchangers in livestock buildings at a site at a specific altitude with a specific average outdoor air temperature

The installation of an energy-saving facility must be preceded by analysis of its financial effectiveness. Among methods enabling such evaluation is the basic net profit calculation method. For this, the annual consumption of electricity for ventilation or of thermal energy for heating must be determined. The calculation formula uses the sum of energies for temperatures within the range from the calculation temperature for the area in question to the long-term average of the maximum temperature at the site, or to the temperature at which the heating power is zero. It is necessary to know the summary time of occurrence of a given temperature during a year. The site data can only be assessed based on long-term meteorological information. In fact, data used by current national standards to describe climatic conditions in the Czech Republic are from the years 1901 to 1950. The dependence of the average yearly temperature on altitude is shown in Fig. 1 for the 1961 1990 and 1991 2000 periods. It is evident that the average temperatures for the latter period are nearly 0.6 K higher than those for the former period, irrespective of the altitude. In this paper the climatic conditions are assessed based on daily data measured throughout the period from 1 January 1991 to 31 December 2000. Weather stations were selected so as to achieve a uniform coverage and continuity of measurement at each site (as far as possible). All the stations lie in the Czech Republic between 48.8° and 50.8° north latitude at altitudes from 158 m to 1324 m. It was the objective of this examination, based on the meteorological data collected to calculate the average number of days and hours during which the temperature during the year is lower than a specific limiting level, in dependence on the average yearly temperature of the site. Fig. 3 shows the average number of days in a year during which a temperature lower than a selected limiting level occurs, as calculated for the 1991 2000 period. The results are presented for 4 areas with average yearly temperatures of 6 °C 7 °C, 7 °C 8 °C, 8 °C 9 °C, and 9 °C 10 °C, respectively. The graphs enables us to ascertain the number of days during which a heating facility is in operation if the facility is activated by outdoor air temperature decrease to below a specific limiting level. If a typical daily temperature wave is considered, the method makes it possible to estimate the number of hours during which the air temperature is lower than the limiting level chosen. The difference between the data for various limiting levels allows us, for an area with a specific average yearly temperature to ascertain the time of occurrence of outdoor temperature within various ranges. The results of calculations are shown in Fig. 4 and Table 1. The method applied enables underlying data to be prepared for the assessment of energy demands for air heating at a given site and for estimation of the energy savings that could be achieved by installing economical air heating facilities in livestock buildings