THE INFLUENCE OF SPRAYING ANGLE ON AERODYNAMIC CHARACTERISTICS OF FGD SPRAY TOWERS

A model for aerodynamic characteristics predictions of flue gas desulfurization scrubber was developed. Droplets motion was considered as two-dimensional and initial droplets velocity and spraying angle were assumed as parameters. The presented model is able to predict pressure drop caused by the presence of spray, local dispersed phase concentration and droplets residence time for co- or counter-current apparatus. The results obtained for constant initial, vertical component of droplets velocity were compared to those evaluated for constant initial drops velocity (module). A range of applicability of one-dimensional model developed only for vertical drops motion is given.     

Polyurethane Foams of Improved Thermal Stability

In reactions of polyetherols prepared from hydroxymethyl derivatives of uric acid and typical oxiranes with isocyanates and water one obtains a new group of polyurethane foams containing purine rings in their structure. These polyurethanes withstand prolonged heating at temperatures as high as 200 °C. Preliminary results on the effect of the type of polyetherol and the composition used in preparation of the polyurethane foams on their properties are presented. The results of studies on thermal stability and mechanical properties of the foams before and after thermal treatment are also reported.

     

The Role of Thromboxane in the Course and Treatment of Ischemic Stroke: Review

Cardiovascular diseases are currently among the leading causes of morbidity and mortality in many developed countries. They are distinguished by chronic and latent development, a course with stages of worsening of symptoms and a period of improvement, and a constant potential threat to life. One of the most important disorders in cardiovascular disease is ischemic stroke. The causes of ischemic stroke can be divided into non-modifiable and modifiable causes. One treatment modality from a neurological point of view is acetylsalicylic acid (ASA), which blocks cyclooxygenase and, thus, thromboxane synthesis. The legitimacy of its administration does not raise any doubts in the case of the acute phase of stroke in patients in whom thrombolytic treatment cannot be initiated. The measurement of thromboxane B2 (TxB2) in serum (a stable metabolic product of TxA2) is the only test that measures the effect of aspirin on the activity of COX-1 in platelets. Measurement of thromboxane B2 may be a potential biomarker of vascular disease risk in patients treated with aspirin. The aim of this study is to present the role of thromboxane B2 in ischemic stroke and to present effective therapies for the treatment of ischemic stroke. Scientific articles from the PubMed database were used for the work, which were selected on the basis of a search for “thromboxane and stroke”. Subsequently, a restriction was introduced for works older than 10 years, those concerning animals, and those without full text access. Ultimately, 58 articles were selected. It was shown that a high concentration of TXB2 may be a risk factor for ischemic stroke or ischemic heart disease. However, there is insufficient evidence to suggest that thromboxane could be used in clinical practice as a marker of ischemic stroke. The inclusion of ASA in the prevention of stroke has a beneficial effect that is associated with the effect on thromboxane. However, its insufficient power in 25% or even 50% of the population should be taken into account. An alternative and/or additional therapy could be a selective antagonist of the thromboxane receptor. Thromboxane A2 production is inhibited by estrogen; therefore, the risk of CVD after the menopause and among men is higher. More research is needed in this area.     

Reactions taking place in the system N,N,N′,N′,N″‐ pentakis(hydroxymethyl)melamine–oxirane in aqueous media

The results of studies on effects of the amount and type of oxirane, amount of catalyst and water, and temperature on the course of reactions taking place in the system N,N,N′,N′,N″‐pentakis(hydroxymethyl)melamine (PHMM)–oxirane carried out in aqueous media are reported. Quantitative determination of the content of functional groups present in the system and of side products formed in reactions of oxirane with water, made it possible to analyze in detail the processes taking place in the system. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 824–836, 2000     

Struktur und Eigenschaften von Mischungen aus Polyamid 6 und isotaktischem Polypropylen,kompatibilisiert mit reaktiven Copolymeren auf der Basis von Polyethylen

Relations between the morphology and the properties of polyamide-6 (PA)/isotactic poly(propylene) (PP) blends were investigated. Poly(ethylene-co-vinyl acetate) and poly(ethylene-co-ethyl acrylate) functionalized with maleic anhydride were used as compatibilizers. The morphology of the blends and interaction between components were determined by simple thermodynamic analysis, differential scanning calorimetrie and electron microscopy. Fracture toughness and life-time measurements on model sandwich samples confirmed the good compatibilization effect of the used materials.     

Synthesis,characterization, and pervaporation properties of segmented poly(urethane‐urea)s

Poly(urethane‐urea)s (PUUs) from 2,4‐tolylene diisocyanate (2,4‐TDI), poly(oxytetramethylene)diols (PTMO) or poly(butylene adipate)diol (PBA), and various diamines were synthesized and characterized by Fourier transform infrared spectroscopy, gel permeation chromatography, differential scanning calorimetry, and density measurements. Transport properties of the dense PUU‐based membranes were investigated in the pervaporation of benzene–cyclohexane mixtures. It was shown that the pervaporation characteristics of the prepared membranes depend on the structure and length of the PUU segments. The PBA‐based PUUs exhibit good pervaporation performance along with a very good durability in separation of the azeotropic benzene–cyclohexane mixture. They are characterized by the flux value of 25.5 (kg μm m⁻² h⁻¹) and the separation factor of 5.8 at 25°C, which is a reasonable compromise between the both transport parameters. The PTMO‐based PUUs display high permeation flux and low selectivity in separation of the benzene‐rich mixtures. At the feed composition of 5% benzene in cyclohexane, their selectivity and flux are in the range of 3.2 to 11.7 and 0.4 to 40.3, respectively, depending on the length of the hard and soft segments. The chemical constitution of the hard segments resulting from the chain extender used does not affect the selectivity of the PUU membranes. It enables, however, the permeability of the membranes to be tailored. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1615–1625, 1999     

Fructose-Rich Diet Is a Risk Factor for Metabolic Syndrome,Proximal Tubule Injury and Urolithiasis in Rats

Excessive consumption of fructose (FR) leads to obesity, metabolic syndrome (MS) and insulin resistance, which are known risk factors for kidney stones. The epidemiological study has suggested the association between fructose consumption and urolithiasis, but the precise mechanism is still not well understood. Male Wistar rats were assigned for 8 weeks to three groups with different FR content in diet: RD (n = 5)—regular diet with a FR <3%; F10 (n = 6)—regular diet with an addition of 10% Fr in drinking water; F60 (n = 5)—60% FR as a solid food. Serum concentration of FR, creatinine (Cr), insulin (Ins), triglycerides (Tg), homocysteine (HCS), uric acid (UA), calcium (Ca), phosphate (Pi), magnesium (Mg) and sodium (Na) were measured. Based on 24 h urine collection the following tests were performed: urine pH, proteinuria (PCR), excretion of N-Acetyl-(D)-Glucosaminidase (NAG), monocyte chemoattractant protein (MCP-1), uric acid (uUAEx), phosphate (uPiEx), calcium (uCaEx), magnesium (uMgEx) and sodium (uNaEx). The creatinine clearance (CrCl) was calculated. Calcium deposits in kidney sections were examined using hematoxylin and eosin (HE) and von Kossa stains. The rats on F10 and F60, as compared to the RD diet, showed a tendency for lower CrCl, higher HCS level and some features of MS as higher Ins and TG levels. Interestingly, F10 (fluid) versus F60 (solid) diet led to higher serum Ins levels. F10 and F60 versus RD demonstrated higher urinary excretion of MCP-1 and NAG which were suggestive for inflammatory injury of the proximal tubule. F10 and F60 as compared to RD showed significantly lower uUAEx, although there were no differences in clearance and fractional excretion of UA. F60 versus RD induced severe phosphaturia (>30×) and natriuria (4×) and mild calciuria. F10 versus RD induced calciuria (3×), phosphaturia (2×) and mild natriuria. Calcium phosphate stones within the tubules and interstitium were found only in rats on FR diet, respectively, in two rats from the F10 group and another two in the F60 group. The rats which developed stones were characterized by significantly higher serum insulin concentration and urinary excretion of calcium and magnesium. A fructose-rich diet may promote development of calcium stones due to proximal tubule injury and metabolic syndrome.     

Derivatives of 1,10- and 4,7-Phenanthrolinaldehydes and Di(N,N-di-ethylamino)ethoxyphenanthrolines as Potential Antitumor Agents

The syntheses of 1,10- and 4,7-phenanthroline derivatives having glycidyl, oxaziridinyl, N, N-diethylaminoethoxy and thiosemicarbazone groups, and related compounds are reported. Their activities against experimental human tumor cells A 549 in vitro in relation to the molecular structures are discussed.     

Conversion of Formyl into Cyano groups in kojic acid derivatives and analogues

It has been revealed that N,N-dimethylhydrazones ( 1a - c , 3a , b ) derived from kojic acid analogs, such as substituted furans ( 3a , b ), 4-pyrones ( 1a , b ) and 4-pyridine ( 1c ), on oxididation with 3-chloroperoxybenzoic acid afford the corresponding nitriles ( 2a-c , 4a , b ). The method has preparative value. The mechanism of the reaction is presented.     

Physico-chemical characterization of walnut shell biochar from uncontrolled pyrolysis in a garden oven and surface modification by ex-situ chemical magnetization

The shells of walnuts (WS) are major refuse in the global fruits and nuts trade. This, otherwise discarded, lignin-rich material can be carbonized to biochar—a value-added product with environmental applications such as carbon sequestration, soil amelioration, and pollutant adsorption. These applications are dictated by structural and chemical characteristics of the biochar carbon. Conventional controlled pyrolysis (CPy) of biomass is cost-intensive and technically too complex for widespread adoption, especially in emerging economies. Here, walnut shell biochar (BWS0) is derived through uncontrolled pyrolysis (UCPy) in a pyrolysis oven and further hybridized as magnetic biochar through ex-situ chemical co-precipitation. The physico-chemical characteristics of biochar and its water-extractable fractions are comprehensively investigated to understand their carbon structure and environmental applicability. The sp² amorphous carbon sequestered in BWS0 is 0.84 kg_CO2/kg_biomass with a BET (N₂) surface area of 292 m²/g and is comparable to biochar from CPy in terms of carbon structure. The polyaromatic hydrocarbons present are only trace amounts of naphthalene, biphenyl, and phenanthrene. The magnetization decreases porosity of BWS0 while greatly facilitating its separation from aqueous media. BWS0 is suitable for adsorption of cations (between pH 2.8 and 9.45) and hydrophobic pollutants with only 19 mg L⁻¹ fouling from their intrinsic dissolved organic carbon. In combination with fast-release N, P fertilizers, BWS0 (C/N of 24.8) is suitable for application in hydrophilic soils at higher loading rates. The results suggest an avenue where WS biochar can also be prepared via UCPy for direct environmental applications. Future investigations into soil incubation and adsorption tests are recommended.

Graphical abstract