Wyniki wyszukiwania - Biblioteka Nauki

1

Charakterystyka stanu reologicznego

100%

Balejko J. A.

|

2006

|

tom R. 11, nr 2

10-12

2

Uogólnione modele reologiczne

80%

Balejko J. A.

|

2006

|

tom R. 11, nr 1

25-28

3

Effects of low-calcium fly ash on the rheology of fresh cement pastes

80%

Grzeszczyk S. , Lipowski G.

|

1998

|

tom Vol. 3, no 4

589-600

EN

Results of the effect of fly ash upon rheological properties of cement pastes have been presented. Bituminous fly ash when added to cement have been found to produce a decrease both in the yield shear stress value and plastic viscosity of cement pastes the greater the higher the fly ash content. A relation between the fine fraction share in the fly ash and the flowability degree of cement pastes was found. The fine fraction content of the fly ash has been proved to be a better parameter to evaluate the influence of the fineness upon the rheology of cement pastes than Blain's specific surface area is.

4

The inflluence of emulsifiers on physical properties and release parameters of creams with caffeine

80%

Dwornicka D. , Wojciechowska K. , Zun M. , Kasperek R. , Swiader K. , Szumilo M. , Poleszak E.

Current Issues in Pharmacy and Medical Sciences

|

2015

|

tom 28

|

nr 2

81-84

EN

Caffeine is well known alkaloid chemical compound belonging to the methyl-xanthines group. It is an active substance that is found in many cosmetic products, as it has a stimulating action on both the central nervous system and the metabolism. Commercially available topical formulations normally contain 3% of caffeine and 7% anticellulite products. The aim of our work was to investigate the properties of four cream preparations. These consisted of 5% of caffeine and one of four different emulsifiers (GSC, Sodium polyacrylate, Emulsifying Base, MDS). In our work, we compared the physical properties (spreadability, slip and tenacity), the rheological structure of the resulting creams and the caffeine release from the obtained preparations. The results showed that the properties of these creams and their drug release depended upon the kind of the emulsifiers utilised. What is more, all preparations have a pseudoplastic character of flow and most of them have significant thixotropy. Furthermore, the amount of released caffeine is the largest from the MDS cream, and this emulsifier seems to be the most optimal in all the examined items.

5

Physical properties and caffeine release from creams prepared with different oils

80%

Wojciechowska K. , Zun M. , Dwornicka D. , Swiader K. , Kasperek R. , Poleszak E.

Current Issues in Pharmacy and Medical Sciences

|

2014

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tom 27

|

nr 4

224-228

EN

Caffeine is a methylxanthine typically found in the Coffee Arabica L plant. Generally, caffeine is well-known as a orally administered mild stimulant of the central nervous system. However, for cosmetic purpose, caffeine is an active compound ingredient, at 7% concentration, in several anticellulite products. The efficiency of this mode of delivery is not fully understood. Hence, the aim of the study was to ascertain the effectiveness of particular carriers to release this ingredient. In so doing, we prepared six creams based upon different oils (Sesame oil, Rice oil, Walnut oil, Coconut oil, Sweet almond oil and Jojoba oil), containing 5% of caffeine, and compared the release of the substance from the obtained preparations. Initially, all of the creams were subjected to a variety of physical tests, among these being for slippage and spreadability. Furthermore, their rheological properties were evaluated. Subsequently, the creams were tested for caffeine release. In the slippage and spreadability tests, the coconut oil-based cream was revealed as having the best parameters. However, the rheological tests showed that all of the preparations had the pseudoplastic character of flowing according to the Ostwald de Waele power law model. The power low index (n) for all the preparations was from 0.2467-0.3179 at 20°C and 0.2821-0.3754 at 32°C. At 20°C, the Sesame oil-, Walnut oil-, Sweet almond oil- and Jojoba oil-based creams were thixotropic, but at 32°C, thixotropy appeared only in the Walnut oil-based creams. The release studies, conducted by way of an extracting chamber (according to Polish Pharmacoeia IX) in the Paddle Apparatus (according to Polish Pharamcopoeia IX), showed that the amount of released caffeine is the largest in the case of Jojoba oil-based cream, at 85.23% ± 0.8% (SD), and the least in the case of Coconut oil-based cream, at 62,78%± 0.87% (SD).

6

Influence of brine on rheological parameters of sealing slurries

80%

Stryczek S. , Hliniak B.

|

2000

|

tom Vol. 45, nr 2

283-301

EN

The rheological parameters of sealing slurries are a significant technological factor in the geoengineering works performed to seal and strengthen the soil and rock mass. The paper presents the results of laboratory analyses of sealing slurries based on various cements and base fluids. The applied cements were selected in view of different C3A content (a phase significantly influencing the rheology of fresh cement slurries). With the elaborated results of laboratory analyses it will be possible to prognose the rheological properties of cement slurries, depending on the chemical and mineral composition of cements and chemical composition of base fluids.

PL

W pracach geoinżynieryjnych, a zwłaszcza typu otworowego związanych z uszczelnianiem i wzmacnianiem ośrodka gruntowego i masywu skalnego bardzo ważnym parametrem technologicznym stosowanym do tego celu zaczynów uszczelniających są jego parametry reologiczne. W artykule przedstawiono wyniki badań laboratoryjnych zaczynów uszczelniających sporządzonych na różnych rodzajach cementów oraz cieczy zarobowych. Badania właściwosci reologicznych świeżych zaczynów uszczelniających, a zwłaszcza typu cementowego wykazały, że zależą one od wielu czynników, do których należą: - powierzchnia właściwa oraz granulacja nieorganicznych spoiw hydraulicznych wchodzących w skład zaczynu uszczelniającego, - iloraz wody i spoiwa hydraulicznego (współczynnik w/s), - skład chemiczny spoiwa hydraulicznego (np. cementu), - skład chemiczny cieczy zarobowej, - obecność i skład chemiczny dodatków wchodzących w skład receptury zaczynu, - sposób i dynamika (czas i szybkość) mieszania zaczynu, - temperatura zaczynu, - szybkość hydratacji, - warunki i sposób pomiaru. Stosowane cementy dobrano pod kątem różnej zawartości C3A jako fazy, która w istotny sposób wpływa na reologię świeżych zaczynów cementowych. Jednym z istotniejszych problemów w geoinżynierii otworowej jest odpowiedni dobór rodzaju oraz parametrów reologicznych zaczynu uszczelniającego górotwór solny. Do tego rodzaju prac stosuje się zaczyny uszczelniające tzw. solankowe sporządzane na osnowie solanki o pełnym nasyceniu. Wpływ chlorku sodu jako zazwyczaj głównego skladnika cieczy zarobowej do sporządzania solankowych zaczynów cementowych jest zróżnicowany w zależności od jego koncentracji i temperatury zaczynu. Sole chlorkowe wprywają w sposób istotny na właściwości reologiczne zaczynów poprzez ich wpływ na szybkość wiązania. Przyspieszające działanie wiązania zaczynów cementowych zależy od wartościowości jonów zawartych w solance. Jest ono większe przy przejściu z jedno- do trójwartościowych jonów. Zauważa się, że kationy i aniony w zależności od ich efektywności przyspieszającego działania na zaczyny sporządzane z cementów portlandzkich mogą być uszeregowane w następującej kolejności: Ca2+ > Mg2+ > Li+ > Na+ > H2O OH- > Cl- > Br- > NO3- > SO2 4 > H2O NaCl działa jako przyspieszacz czasu wiązania zaczynu przy koncentracji do 10% (wagowo w stosunku do masy cieczy zarobowej). Przy koncentracji między 10% a 18% NaCl, jego oddziaływanie na czas wiązania jest praktycznie niewidoczne i uważa się, że czas początku wiązania jest podobny do tego, jaki uzyskuje się przy stosowaniu wody pitnej jako cieczy zarobowej. Przy zawartości NaCl w cieczy zarobowej powyżej 18% (wagowo), oddziałuje on jako opóźniacz czasu wiązania zaczynów cementowych. Opracowane wyniki z badań laboratoryjnych pozwolą na prognozowanie właściwości reologicznych zaczynów cementowych w zależności od składu chemicznego i mineralnego cementów oraz składu chemicznego cieczy zarobowej.

7

Unsteady MHD flow in the presence of radiation

80%

Perdikis C. , Rapti E.

|

2006

|

tom Vol. 11, no 2

383-390

EN

A magnetohydrodynamic unsteady free convection flow in the presence of radiation is studied. The fluid is considered to be a gray, absorbing-emitting radiating but non-scattering medium. The differential equations governing the problem are solved exactly. The effects of radiation and suction parameters on the temperature and velocity fields are given.

8

Effect of Calcined Colemanite Addition on the Rheological Behaviour of Porcelain Suspension

80%

Özdemir Y. , Akpınar S. , Abbak S. , Evcin A.

Acta Physica Polonica A

|

2017

|

tom 132

|

nr 3

825-829

EN

A standard composition for hard porcelain production was prepared by mixing 50 wt% kaolin, 25 wt% potassium feldspar and 25 wt% quartz. Calcined colemanite powders were added to the porcelain formulation by replacing the potassium feldspar up to 5 wt% to explore its effect on the rheological behaviour of porcelain slip casting. A rheological study has been carried out in order to optimize the processing of the slip casting by using a rotational stress-controlled rheometer. The measurements were performed at constant temperature (25°C) using a parallel plate configuration. Sweep measurements were then conducted in the shear rates ranging from about 0.1-1000 s¯¹. The stability of the suspensions with ammonium polyacrylate (Darvan 821A) was determined in order to select the suitable dispersant amount. In order to achieve casting of acceptable characteristics on a plaster of Paris mould, the slurry should have the appropriate thixotropic or shear-thinning behaviours. Therefore, the same favourable thixotropic behaviour of slurries of different amount of calcined colemanite powders, the solid contents of the slurries have been optimised.

9

Rheological behaviour of protein interfacial layers in emulsion stability

80%

Izmailova V. N. , Yampolskaya G. P.

|

1999

|

tom Vol. 4, no spec.

141-144

EN

Rheological properties of interface layers determine the emulsion stability against coalescence and effect mechanics and flow of emulsions. The role in emulsion stability of Rehbinder structure-mechanical barrier due to elasticity of interfacial layers formed by fine dispersed solids and liquid droplets, or adsorbed polymers, or multilayers of adsorbed surfactants of any nature is emphasized. Emulsions are systems of great importance because of their widespread application. A number of questions of emulsion properties and production was the object of many investigations over a long period of time, of which emulsion stability is the most general.

10

Rheological properties of cement pastes containing fly ash

80%

Grzeszczyk S. , Lipowski G.

|

1999

|

tom Vol. 4, no spec.

215-220

EN

In this paper the analysis of fly ash influence on rheological properties of cement pastes have been carried out. It was pointed that rheological properties of cement pastes containing fly ash from bituminous coal depend mostly on content fly ash in cement and on the quantity of fine fraction in fly ash as well as on the shape of fly ash particle.

11

Rheology of injection moulding suspension prepared from nanosized plasma processed AlN powder

80%

Palcevskis E. , Jakobsons E. , Faitelson L.

|

1999

|

tom Vol. 4, no spec.

375-380

EN

The rheological properties (flow curves and viscoelastic behavior) of injection moulding suspension prepared from nanosized plasma processed AlN powder and paraffin wax were investigated in the broad region of shear rates (0.07-1350 s-1). Two viscosity platoaux are observed on the flow curves and the values of two yield stresses are obtained. The linear viscoelastic region is not reached at the lowest deformation amplitude (0.66 %). Higher values of dynamic viscosity than those of effective viscosity at 'gamma'='omega' are observed in all the range of the used frequency and shear rate (0.1-80 s-1). The rebuilding of destroyed particle packing structure during ultrasound or shear treatment is observed. It results in the dependence of rheologic properties on the pretreatment history of suspensions.

12

Ustalanie składu mieszanek betonów samozagęszczalnych w oparciu o właściwości reologiczne zapraw

80%

Mądrawski J.

|

2006

|

tom T. 11, nr 1

14-18

PL

W pracy przedstawiono wyniki badań wpływu ilości superplastyfikatora na właściwości zapraw oraz określono zależności pomiędzy właściwościami reologicznymi zapraw i mieszanek betonów samozagęszczalnych. Wykonano badania zmiany rozpływu zaczynów w zależności od ilości zastosowanego superplastyfikatora. Dokonano oceny zależności pomiędzy rozpływem zapraw, a rozpływem mieszanek betonowych, wykonanych według tych samych receptur.

EN

Results of research into influence of superplasticizer quantity on mortars properties and dependences between rheological properties of mortars and concrete mixtures have been presented in the paper. Researches on spreading of cement leaven depending on quantity of used superplasticizer have also been done. Evaluation of dependences between mortars spreading and concrete mixtures based on the same recipes have been carried out.

13

Metodyka określania modelu reologicznego cieczy wiertniczej

80%

Wiśniowski R.

|

2001

|

tom R. 18/1

247-261

PL

W artykule przedstawiono czynniki wpływające na opory przepływu cieczy wiertniczych. Podano algorytm obliczania oporów przepływu oraz pokazano wpływ przyjętego modelu reologicznego płuczki wiertniczej na uzyskiwane wyniki obliczeń. Następnie przedstawiono zasady wykorzystania analizy regresji do wyznaczania parametrów reologicznych cieczy wiertniczych. Na wybranym przykładzie zaprezentowano metodykę doboru optymalnego modelu reologicznego cieczy wiertniczej z wykorzystaniem metod numerycznych.

EN

The factors influencing the resitivity of mud fluids have been presented in this paper. The calculation algorithm for flow resitivities was given and the influence of the assumed rheological model of a drilling mud on the obtained results was shown. Then the principles of the use of regression analysis for rheological parameters of drilling fluids were presented. The methodics of selection of an optimum rheological model of a drilling fluid with the use of numerical methods was presented on an example.

14

Rheology of rock massive as a factor of sinergetic mechanism of geocatastrophe

70%

Vilegzhanin V. N.

|

1999

|

tom Vol. 4, no spec.

33-37

EN

In the report the basic accent is concentrated on the general approach to the description of reological model of mining rocks, interrelation of their reological properties with stages of crypticy and destruction. Synergetical mechanism of irreversible deformations and their influence on absorb - filtering, durability and temperature characteristics of a mountain file is shown from positions of nonequilibrum thermodynamics. It allows to use reology laws of mining rocks for forecast and study of a nature of geoaccidents.

15

Viscoelastic behaviour of polysiloxane - based compositions over a wide frequency and temperature range

70%

Śmigasiewicz S. , Gałąź R. , Kurcok M.

|

1999

|

tom Vol. 4, no spec.

319-323

EN

Dynamic, torsion mechanical studies of two polysiloxane based compositions, Polastosil ABM45 and R-P, in wide frequency (0.2 - 100 Hz) and temperature (-140 - 0oC) ranges and for linear range of strain amplitude ('gamma' = 0.2 %) are presented. The observed G'- minima, near -90oC, magnitudes of which are a decreasing function of frequency proved to be the manifestation of some reversible kinetic transition to a more ordered, crystalline structure .The enthalpy of activation for that transition was estimated to be of the order of 19 kJ/mole. On the basis of DSC measurements the average number of links between polymer chains formed during the crystalization was found to be within the range of 120 - 600, depending on the preliminary cooling rate.

16

Research into the influence of short-term ageing on the change in the rheological properties of mastics containing fillers of different origin

70%

Grabowski W. , Wilanowicz J. , Słowik M. , Soból T.

|

2007

|

tom No. 10

39-49

EN

The object of the research were mastics containing limestone filler and mineral dust received from a dust collecting system. The main purpose of the analysis was the evaluation of the influence of ageing on the rheological properties of the mastics. The mastics were prepared with limestone filler and fillers received from the dust collecting system of an asphalt plant: basalt and melaphyre. Some samples were made by mixing fillers from the asphalt plant with the limestone filler. Special attention has been paid to the research into the influence of the filler type on the mastics rheological properties, before and after ageing, using the TFOT laboratory method. As the estimation measure of the change in the rheological properties caused by the ageing process, the change of the following values has been assumed: softening point, penetration at 5 and 25°C, ductility at 25°C and dynamic viscosity determined at 60. 90 and 135°C. All the tests were carried out before and after the ageing using the TFOT laboratory method.

17

THE INFLUENCE OF THE ADDITION OF COLLAGEN ON THE RHEOLOGICAL PROPERTIES OF CHITOSAN CHLORIDE SOLUTIONS

70%

Owczarz P. , Rył A. , Modrzejewska Z. , Dziubiński M.

Progress on Chemistry and Application of Chitin and its Derivatives

|

2017

|

tom 22

176 - 189

EN

Colloidal solutions of chitosan of crab origin with the addition of collagen obtained from cowhide were studied. Were presents the influence of collagen concentration and the method of preparing the sample on the obtained mechanical properties of the solutions and the observed phase transition temperature. Rheological measurements were performed to determine the viscoelastic properties and phase transition temperatures of these solutions. The study was conducted in the temperature range of 5–60°C with the use of classical techniques of rotational rheometry in the cone-plate measurement system. A significant influence of a collagen addition to chitosan chloride solutions on the viscoelastic properties of the systems was observed. The addition of collagen in all the cases increased the sol–gel phase transition temperature in comparison with the chitosan chloride solution containing β-glycerophosphate.

18

Mixing system for highly concentrated fine-grained suspensions

70%

Moravec J. , Jirout T. , Rieger F. , Krátký L.

Polish Journal of Chemical Technology

|

2009

|

tom 11

|

nr 4

52-56

EN

The mixing equipment for highly concentrated fine-grained suspensions must be designed differently from the equipment in which a suspension with a low concentration of the solid phase or bigger particles is mixed. It is due to the different rheological properties of the suspensions. In this work we are trying to find a suitable mixing system for a highly concentrated fine-grained suspension. The aim was to determine an effect of particular geometrical parameters of the tested mixing systems on a suspension process, especially from the energetic viewpoint. The energetic costs of all the used mixing systems were compared on the basis of the power consumption which was necessary for reaching the state of sufficient suspension movement in the whole mixed bulk. As a result, it was confirmed that multistage impellers can be used even in standard vessels (with a liquid level height equal to a vessel diameter) with a profit. During experiments, the state of sufficient movement was determined by a visual observation of the suspension at the vessel bottom, at the wall and also at the suspension level.

19

Nowa generacja urządzeń do oceny właściwości reologicznych materiałów lepkosprężystych

60%

Balejko J. A.

|

2006

|

tom R. 11, nr 6

28-29

20

Szybkość sedymentacji fazy rozproszonej jako wielkość charakteryzująca stabilność zawiesin farmaceutycznych

60%

Dziubiński M. , Witczak-Stawicka A.

|

2008

|

tom Nr 6

23-24

PL

W pracy przedstawiono wpływ stężenia cząstek ciała stałego i stężenia zagęstnika na zmianę szybkości sedymentacji oraz własności reolo- gicznych wybranych zawiesin farmaceutycznych.

EN

Results of investigations on the effect of particle properties and thickener concentration on rheological parameters and sedimentation rate of suspensions to be applied in the pharmaceutical industry are presented in the paper.