84 research outputs found
The D2-Law of Droplet Evaporation When Calculating the Droplet Evaporation Process of Liquid Containing Solid State Catalyst Particles
The review presents the D2-law of droplet evaporation, which is used to describe the spraying process involving the evaporation of droplets. This law, the subject of numerous publications, can be successfully applied to describe the droplet evaporation process under various conditions, including the calculations of the process of feeding the boiler with a liquid that contains catalyst particles. To date, not a lot of work has been devoted to this issue. The paper is a continuation of previous research concerning the spraying of liquids with a catalyst, which improves the efficiency of the process. The conducted analysis showed that the experimental data from previously published work are very compatible with the data obtained from the D2-law of droplet evaporation. At the standard speed of about 20 m/s of an aerosol flowing through a dust duct, droplets in the stream should be observed up to a distance of 1 m from the outlet of the apparatus supplying the system. Under such flow conditions, a droplet’s lifetime must be above 0.05 s. The dependence between a droplet’s lifetime and its diameter and temperature was determined. The obtained results confirmed that the effective droplet diameter is above 30 µm. Such droplets must be generated and then fed to the boiler for the catalyst to work properly. This law is an engineering approach to the problem, which uses relatively simple model equations in order to determine the evaporation time of a droplet
Direct aperture optimization as a means of reducing the complexity of intensity modulated radiation therapy plans
Intensity Modulated Radiation Therapy (IMRT) is a means of delivering radiation therapy where the intensity of the beam is varied within the treatment field. This is done by dividing a large beam into many small beamlets. Dose constraints are assigned to both the target and sensitive structures and computerised inverse optimization is performed to find the individual weights of this large number of beamlets. The computer adjusts the intensities of these beamlets according to the required planning dose objectives. The optimized intensity patterns are then decomposed into a series of deliverable multi leaf collimator (MLC) shapes in the sequencing step
Synthesis of air‐stable, odorless thiophenol surrogates via Ni‐Catalyzed C−S cross‐coupling
Thiophenols are versatile synthetic intermediates whose practical appeal is marred by their air sensitivity, toxicity and extreme malodor. Herein we report an efficient catalytic method for the preparation of S-aryl isothiouronium salts, and demonstrate that these air-stable, odorless solids serve as user-friendly sources of thiophenols in synthesis. Diverse isothiouronium salts featuring synthetically useful functionality are readily accessible via nickelcatalyzed C-S cross-coupling of (hetero)aryl iodides and thiourea. Convenient, chromatography-free isolation of these salts is achieved via precipitation, allowing the methodology to be translated directly to large scales. Thiophenols are liberated from the corresponding isothiouronium salts upon treatment with a weak base, enabling an in situ release / S-functionalization strategy that entirely negates the need to isolate, purify or manipulate these noxious reagent
Melatonin Promotes Oligodendroglial Maturation of Injured White Matter in Neonatal Rats
OBJECTIVE:To investigate the effects of melatonin treatment in a rat model of white matter damage (WMD) in the developing brain. Additionally, we aim to delineate the cellular mechanisms of melatonin effect on the oligodendroglial cell lineage. METHODS:A unilateral ligation of the uterine artery in pregnant rat at the embryonic day 17 induces fetal hypoxia and subsequent growth restriction (GR) in neonatal pups. GR and control pups received a daily intra-peritoneal injection of melatonin from birth to post-natal day (P) 3. RESULTS:Melatonin administration was associated with a dramatic decrease in microglial activation and astroglial reaction compared to untreated GR pups. At P14, melatonin prevented white matter myelination defects with an increased number of mature oligodendrocytes (APC-immunoreactive) in treated GR pups. Conversely, melatonin was not found to be associated with an increased density of total oligodendrocytes (Olig2-immunoreactive), suggesting that melatonin is able to promote oligodendrocyte maturation but not proliferation. These effects appear to be melatonin-receptor dependent and were reproduced in vitro. INTERPRETATION:These data suggest that melatonin has a strong protective effect on developing damaged white matter through decreased microglial activation and oligodendroglial maturation leading to a normalization of the myelination process. Consequently, melatonin should be a considered as an effective neuroprotective candidate not only in perinatal brain damage but also in inflammatory and demyelinating diseases observed in adults
Hematopoietic stem cell mobilization with the reversible CXCR4 receptor inhibitor plerixafor (AMD3100)—Polish compassionate use experience
Recent developments in the field of targeted therapy have led to the discovery of a new drug, plerixafor, that is a specific inhibitor of the CXCR4 receptor. Plerixafor acts in concert with granulocyte colony-stimulating factor (G-CSF) to increase the number of stem cells circulating in the peripheral blood (PB). Therefore, it has been applied in the field of hematopoietic stem cell mobilization. We analyzed retrospectively data regarding stem cell mobilization with plerixafor in a cohort of 61 patients suffering from multiple myeloma (N = 23), non-Hodgkin’s lymphoma (N = 20), or Hodgkin’s lymphoma (N = 18). At least one previous mobilization attempt had failed in 83.6% of these patients, whereas 16.4% were predicted to be poor mobilizers. The median number of CD34+ cells in the PB after the first administration of plerixafor was 22/μL (range of 0–121). In total, 85.2% of the patients proceeded to cell collection, and a median of two (range of 0–4) aphereses were performed. A minimum of 2.0 × 106 CD34+ cells per kilogram of the patient’s body weight (cells/kg b.w.) was collected from 65.6% of patients, and the median number of cells collected was 2.67 × 106 CD34+ cells/kg b.w. (0–8.0). Of the patients, 55.7% had already undergone autologous stem cell transplantation, and the median time to neutrophil and platelet reconstitution was 12 and 14 days, respectively. Cases of late graft failure were not observed. We identified the diagnosis of non-Hodgkin’s lymphoma and previous radiotherapy as independent factors that contributed to failure of mobilization. The current report demonstrates the satisfactory efficacy of plerixafor plus G-CSF for stem cell mobilization in heavily pre-treated poor or predicted poor mobilizers
Comparison of direct machine parameter optimization versus fluence optimization with sequential sequencing in IMRT of hypopharyngeal carcinoma
Interactions of melatonin with mammalian mitochondria. Reducer of energy capacity and amplifier of permeability transition.
Melatonin, a metabolic product of the amino acid tryptophan, induces a dose-dependent energy drop correlated with a decrease in the oxidative phosphorylation process in isolated rat liver mitochondria. This effect involves a gradual decrease in the respiratory control index and significant alterations in the state 4/state 3 transition of membrane potential (ΔΨ). Melatonin, alone, does not affect the insulating properties of the inner membrane but, in the presence of supraphysiological Ca2+, induces a ΔΨ drop and colloid-osmotic mitochondrial swelling. These events are sensitive to cyclosporin A and the inhibitors of Ca2+ transport, indicative of the induction or amplification of the mitochondrial permeability transition. This phenomenon is triggered by oxidative stress induced by melatonin and Ca2+, with the generation of hydrogen peroxide and the consequent oxidation of sulfydryl groups, glutathione and pyridine nucleotides. In addition, melatonin, again in the presence of Ca2+, can also induce substantial release of cytochrome C and AIF (apoptosis-inducing factor), thus revealing its potential as a pro-apoptotic agent
Comments on adult education
The paper presents the characteristics of adult learning environment and models of working with adult learners. Definitions of lifelong adult education, with an emphasis on social sciences are given. Functions that lifelong adult education can perform are presented and described. Forms and methods of lifelong education are characterized. Taking into account different criteria, the major differences in the models of adult education – technological, humanistic and critical are described. The importance of lifelong adult education is stressed, and some of the positive characteristics of teaching adults are highlighted.W artykule przedstawiono charakterystykę środowiska nauczania dorosłych i modeli pracy z dorosłymi uczniami. Podane zostały definicje kształcenia ustawicznego dorosłych, ze szczególnym uwzględnieniem nauk społecznych. Opisano i przedstawiono funkcje, które mogą zostać spełnione przez kształcenie ustawiczne dorosłych. Scharakteryzowane zostały formy i metody kształcenia ustawicznego. Biorąc pod uwagę różne kryteria, opisane zostały najważniejsze różnice w modelach edukacji dorosłych - technologicznym, humanistycznym i krytycznym. Zostało podkreślone znaczenie kształcenia ustawicznego dorosłych, a także zostały wyróżnione niektóre z pozytywnych cech nauczania dorosłych
Notes on research of marine infrasound in floating objects
Scharakteryzowano ogólnie znaczenie działania infradźwięków na organizm ludzki. Wskazano podstawowe źródła infradźwięków. Przedstawiono zestawienie wybranych badań klinicznych wpływu drgań o częstotliwości poniżej 20 Hz na organizm ludzki w ostatnich latach.The effect of infrasound on human body is characterized in general. The basic sources of infrasound are indicated. A summary of recent research papers on clinical effects of vibration frequency below 20 Hz on human body is presented
Problems of Ship Power Plant Reliability Research
Przedstawiono wyniki analizy uszkodzeń systemów siłowni zarejestrowanych na 10 statkach w czasie przeciętnego rejsu trwającego około sześciu miesięcy. Do weryfikacji hipotezy, że pochodzą one z jednej populacji, albo inaczej, że można je traktować jako dziesięć realizacji tej samej próby losowej, zastosowano test sumy rang Kruskala-Wallisa. Test został przeprowadzony zarówno dla chwil kolejnych uszkodzeń, jak i dla czasów pomiędzy kolejnymi uszkodzeniami instalacji. Do weryfikacji hipotezy o zgodności rozkładu empirycznego dla analizowanych instalacji siłowni okrętowych z wybranymi czterema rozkładami: wykładniczym, Weibulla, logarytmo-normalnym oraz gamma posłużono się testem zgodności Kołmogorowa-Smirnowa.The paper presents analysis results based on cases of power plant system damage from 10 ships, registered during a voyage lasting about six months on the average. For the verification of the hypothesis that they stem from one population, or to put it in a different way, that they can be treated as realisations of the same random trial, Kruskal-Wallis ranks sum test was applied. The test was carried out both for the moments of successive damage and for the time intervals for successive installation damage. For the verification of the hypothesis about the conformity of the empirical distribution with selected four distributions: exponential, Weibull's, log-normal and gamma distribution for the analysed power plant installations, the Kolmogorov-Smirnov goodness of fit test was used
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