Coagulation followed by floc separation is a key process for the removal of algal organic matter (AOM) in water treatment. Besides optimizing coagulation parameters, knowledge of the properties of AOM-flocs is essential to maximizing AOM removal. However, the impact of AOM on the floc properties remains unclear. This study investigated how peptides/proteins derived from the cellular organic matter (COM) of the cyanobacterium Microcystis aeruginosa influenced the size, structure, and shape of flocs formed at different shear rates (G). Flocs formed by kaolinite, COM-peptides/proteins and a mixture of the same were studied, and the effect of intermolecular interactions between floc components on floc properties was assessed. The coagulation experiments were performed in a Taylor-Couette reactor, with aluminum (Al) or ferric sulphate (Fe) utilized as coagulants. Image analysis was performed to gauge floc size and obtain data on fractal dimension. It was found that floc properties were affected by the presence of the COM-peptides/proteins and the coagulant used. COM-peptides/proteins increased floc size and porosity and widened floc size distributions. The Fe coagulant produced larger and less compact flocs than Al coagulant. Moreover, the decrease in floc size that occurred in parallel with increase in shear rate was not smooth in progress. A rapid change for the kaolinite-coagulant suspension and two rapid changes for the suspensions containing COM were observed. These were attributed to various intermolecular interactions between floc components participating in coagulation at different G. Based on the results obtained, shear rates suitable for efficient separation of flocs containing COM were suggested.

• Klíčová slova
• Algal organic matter, Coagulation, Floc size, Image analysis, Water treatment,
• MeSH
• bakteriální proteiny MeSH
• čištění vody metody   MeSH
• flokulace MeSH
• Microcystis * MeSH
• mikrobiologie vody * MeSH
• peptidy MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• bakteriální proteiny MeSH
• peptidy MeSH

Declines in endothelial function can take place rapidly across the menopause transition, placing women at heightened risk for atherosclerosis. Disturbed patterns of conduit artery shear, characterized by greater oscillatory and retrograde shear, are associated with endothelial dysfunction but have yet to be described across menopause. Healthy women, who were not on hormone therapy or contraceptives, were classified into early perimenopausal, late perimenopausal, and early postmenopausal stage. Resting antegrade, retrograde, and oscillatory shear were calculated from blood velocity and diameter measured in the brachial and common femoral artery using Doppler ultrasound. Serum was collected for measurements of estradiol, follicle-stimulating hormone (FSH), and luteinizing hormone. After adjusting for age, brachial artery oscillatory shear was significantly higher in early postmenopausal women (n = 15, 0.17 ± 0.08 a.u.) than both early (n = 12, 0.08 ± 0.05 a.u., P < 0.05) and late (n = 8, 0.08 ± 0.04 a.u) perimenopausal women, and retrograde shear was significantly greater in early postmenopausal versus early perimenopausal women (-19.47 ± 12.97 vs. -9.62 ± 6.11 sec-1 , both P < 0.05). Femoral artery oscillatory and retrograde shear were greater, respectively, in early postmenopausal women (n = 15, 0.19 ± 0.08 a.u.; -13.57 ± 5.82 sec-1 ) than early perimenopausal women (n = 14, 0.11 ± 0.08 a.u.; -8.13 ± 4.43 sec-1 , P < 0.05). Further, Pearson correlation analyses revealed significant associations between FSH and both retrograde and oscillatory shear, respectively, in the brachial (r = -0.40, P = 0.03; r = 0.43, P = 0.02) and common femoral artery (r = -0.45, P = 0.01; r = 0.56, P = 0.001). These results suggest menopause, and its associated changes in reproductive hormones, adversely influences conduit arterial shear rate patterns to greater oscillatory and retrograde shear rates.

• Klíčová slova
• Menopause transition, oscillatory shear, retrograde shear,
• MeSH
• arterie diagnostické zobrazování   fyziologie   MeSH
• cévní endotel fyziologie   MeSH
• dospělí MeSH
• estradiol krev   MeSH
• folikuly stimulující hormon krev   MeSH
• lidé středního věku MeSH
• lidé MeSH
• luteinizační hormon krev   MeSH
• menopauza krev   fyziologie   MeSH
• reologie krve * MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• estradiol MeSH
• folikuly stimulující hormon MeSH
• luteinizační hormon MeSH

Shear wave elastography (SWE) is a non-invasive diagnostic imaging technique that maps the elastic properties of tissues. This modality is being increasingly developed in other areas of medicine, offering a new type of high-quality ultrasound examination, since it increases specificity and thus improves diagnostic accuracy. This method is similar to manual palpation, showing the elastic properties of biological tissues and providing a kind of reconstruction of the internal structure of soft tissues based on measurement of the response to tissue compression. In ophthalmology, it already appears promising for diagnosis and in evaluating changes in extraocular muscles and orbital tissues in patients with endocrine orbitopathy. Shear wave elastography offers three main innovations: the quantitative aspect, dimensional resolution, and real-time imaging ability. Determination of the utilization rate of this method and its inclusion in the diagnosis of endocrine orbitopathy is still a question and the object of clinical studies currently under way.

• Klíčová slova
• Elastography, Module d’Young, Onde de cisaillement, Ophtalmologie, Ophthalmology, Shear wave, Ultrason, Ultrasound, Young's modulus, Élastographie,
• MeSH
• diagnostické techniky oftalmologické * MeSH
• elastografie metody   MeSH
• lidé MeSH
• modul pružnosti MeSH
• nemoci endokrinního systému komplikace   diagnóza   MeSH
• oční nemoci diagnóza   etiologie   MeSH
• senzitivita a specificita MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Flowability of powder excipients is directly influenced by their size and shape although the granulometric influence of the flow and shear behaviour of particulate matter is not studied frequently. In this work, the influence of particle size on the mass flow rate through the orifice of a conical hopper, and the cohesion and flow function was studied for four free-flowable size fractions of sorbitol for direct compression in the range of 0.080-0.400 mm. The particles were granulometricaly characterized using an optical microscopy; a boundary fractal dimension of 1.066 was estimated for regular sorbitol particles. In the particle size range studied, a non-linear relationship between the mean particle size and the mass flow rate Q10 (g/s) was detected having amaximum at the 0.245mm fraction. The best flow properties of this fraction were verified with aJenike shear tester due to the highest value of flow function and the lowest value of the cohesion. The results of this work show the importance of the right choice of the excipient particle size to achieve the best flow behaviour of particulate material.Key words: flowability size fraction sorbitol for direct compaction Jenike shear tester fractal dimension.

• MeSH
• fraktály * MeSH
• pevnost ve smyku MeSH
• pomocné látky * MeSH
• prášky, zásypy, pudry MeSH
• sorbitol * MeSH
• velikost částic MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• pomocné látky * MeSH
• prášky, zásypy, pudry MeSH
• sorbitol * MeSH

BACKGROUND/AIMS: The feeding artery of dialysis vascular access is subjected to unusually high wall shear stress (WSS), a hemodynamic factor leading to vasodilatation, for at least several months after access creation. Physiologically, high WSS leads to compensatory endothelium-dependent vasodilatation. We supposed that the dilatation of the feeding artery continues to lower WSS during longer time period after access creation and that this process is limited by risk factors of endothelial dysfunction. METHODS: We examined the feeding artery of vascular accesses within 3 months, 1 and 2 years after access creation. By ultrasonography, we obtained internal diameter and blood velocity in the feeding arteries. We calculated wall shear rate (WSR). RESULTS: We examined 75 patients. Internal diameter rose from 3.9 +/- 0.1 mm (3 months) to 4.3 +/- 0.2 mm within the first year and to 4.6 +/- 0.2 mm within the second. Similarly, mean WSR decreased from 1,839 +/- 117 to 1,629 +/- 123 s(-1) and to 1,159 +/- 109 s(-1), respectively. The vasodilatation was limited by diabetes mellitus, hypercholesterolemia and hypertriglyceridemia. CONCLUSIONS: The feeding artery continues to dilate 2 years after access creation, with a simultaneous decrease in WSR. This process is dampened in patients with diabetes mellitus and dyslipidemia.

• MeSH
• arterie diagnostické zobrazování   fyziologie   MeSH
• cévní endotel fyziologie   MeSH
• diabetes mellitus patofyziologie   MeSH
• dialýza ledvin * MeSH
• duplexní dopplerovská ultrasonografie MeSH
• fyziologická adaptace MeSH
• hypercholesterolemie patofyziologie   MeSH
• hypertriglyceridemie patofyziologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• pevnost ve smyku MeSH
• senioři MeSH
• vazodilatace fyziologie   MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Good flow and compaction properties are necessary for the manipulation of particulate material in the pharmaceutical industry. The influence of the addition of an alternative sweetener, rebaudioside A, in a concentration 0.2% w/w and 0.5% w/w on the flow, shear and compaction properties of sorbitol for direct compaction, Merisorb® 200, was investigated in this work. Rebaudioside A worsened the flow properties of sorbitol: the Hausner ratio, the compressibility index and the mass flow rate through the aperture of a model hopper. Using a Jenike shear cell revealed a significant increase in cohesion leading to the decrease of the flow function; moreover, the addition of rebaudioside A increased the total energy for compression of tablets and plasticity estimated by the force-displacement method. Finally, the tablets showed a higher tensile strength and needed longer time to disintegrate compared to the tablets made of sorbitol itself. In view of the results for the free-flowable excipient, sorbitol, the effects of stevia even for a 0.2% w/w concentration have to be carefully considered, particularly whenever used in pharmaceutical formulations of poor flow properties.

• Klíčová slova
• Jenike shear tester, Sorbitol, flowability, force–displacement method, rebaudioside A, tablets,
• MeSH
• diterpeny kauranové chemie   MeSH
• farmaceutická technologie metody   MeSH
• pevnost v tahu MeSH
• pomocné látky chemie   MeSH
• příprava léků metody   MeSH
• sladidla chemie   MeSH
• sorbitol chemie   MeSH
• Stevia chemie   MeSH
• tablety chemie   MeSH
• tlak MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• diterpeny kauranové MeSH
• pomocné látky MeSH
• rebaudioside A MeSH Prohlížeč
• sladidla MeSH
• sorbitol MeSH
• tablety MeSH

Adiabatic shear banding (ASB) is a unique dynamic failure mechanism that results in an unpredicted catastrophic failure due to a concentrated shear deformation mode. It is universally considered as a material or structural instability and as such, ASB is hardly controllable or predictable to some extent. ASB is modeled on the premise of stability analyses. The leading paradigm is that a competition between strain (rate) hardening and thermal softening determines the onset of the failure. It was recently shown that microstructural softening transformations, such as dynamic recrystallization, are responsible for adiabatic shear failure. These are dictated by the stored energy of cold work, so that energy considerations can be used to macroscopically model the failure mechanism. The initial mechanisms that lead to final failure are still unknown, as well as the ASB formation mechanism(s). Most of all - is ASB an abrupt instability or rather a gradual transition as would be dictated by microstructural evolutions? This paper reports thorough microstructural characterizations that clearly show the gradual character of the phenomenon, best described as a nucleation and growth failure mechanism, and not as an abrupt instability as previously thought. These observations are coupled to a simple numerical model that illustrates them.

• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

This study aimed to measure the whole blood viscosity (WBV) in racehorses using a new viscometer and establish reference values, as well as to investigate the correlation between the WBV and the haematological parameters and serum chemistry. WBV measurements were conducted on 51 Thoroughbred horses using a novel U-shaped scanning capillary-tube viscometer. The reference values for the WBV were determined at various shear rates ranging from 1 s-1 to 1 000 s-1. Correlation analyses were performed to examine the correlation between the WBV and the haematological and serum chemistry parameters. The findings provide valuable reference data for the WBV in Thoroughbred horses and enhance understanding of the relationship between the WBV and routine blood tests in equine health assessment.

• Klíčová slova
• haemorheology, shear rates, viscometer,
• Publikační typ
• časopisecké články MeSH

OBJECTIVE: Liver stiffness measurement (LSM) is a tool used to screen for significant fibrosis and portal hypertension. The aim of this retrospective multicentre study was to develop an easy tool using LSM for clinical outcomes in advanced chronic liver disease (ACLD) patients. DESIGN: This international multicentre cohort study included a derivation ACLD patient cohort with valid two-dimensional shear wave elastography (2D-SWE) results. Clinical and laboratory parameters at baseline and during follow-up were recorded. LSM by transient elastography (TE) was also recorded if available. The primary outcome was overall mortality. The secondary outcome was the development of first/further decompensation. RESULTS: After screening 2148 patients (16 centres), 1827 patients (55 years, 62.4% men) were included in the 2D-SWE cohort, with median liver SWE (L-SWE) 11.8 kPa and a model for end stage liver disease (MELD) score of 8. Combination of MELD score and L-SWE predict independently of mortality (AUC 0.8). L-SWE cut-off at ≥20 kPa combined with MELD ≥10 could stratify the risk of mortality and first/further decompensation in ACLD patients. The 2-year mortality and decompensation rates were 36.9% and 61.8%, respectively, in the 305 (18.3%) high-risk patients (with L-SWE ≥20 kPa and MELD ≥10), while in the 944 (56.6%) low-risk patients, these were 1.1% and 3.5%, respectively. Importantly, this M10LS20 algorithm was validated by TE-based LSM and in an additional cohort of 119 patients with valid point shear SWE-LSM. CONCLUSION: The M10LS20 algorithm allows risk stratification of patients with ACLD. Patients with L-SWE ≥20 kPa and MELD ≥10 should be followed closely and receive intensified care, while patients with low risk may be managed at longer intervals.

• Klíčová slova
• chronic liver disease, clinical decision making, liver cirrhosis, liver failure, portal hypertension,
• MeSH
• algoritmy MeSH
• chronická nemoc MeSH
• dospělí MeSH
• elastografie * MeSH
• lidé středního věku MeSH
• lidé MeSH
• míra přežití MeSH
• nemoci jater diagnóza   etiologie   mortalita   MeSH
• prediktivní hodnota testů MeSH
• retrospektivní studie MeSH
• ROC křivka MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• multicentrická studie MeSH
• pozorovací studie MeSH
• práce podpořená grantem MeSH

This paper studies the influence of displacement rate on mode II delamination of unidirectional carbon/epoxy composites. End-notched flexure test is performed at displacement rates of 1, 10, 100 and 500 mm/min. Experimental results reveal that the mode II fracture toughness GIIC increases with the displacement, with a maximum increment of 45% at 100 mm/min. In addition, scanning electron micrographs depict that fiber/matrix interface debonding is the major damage mechanism at 1 mm/min. At higher speeds, significant matrix-dominated shear cusps are observed contributing to higher GIIC. Besides, it is demonstrated that the proposed rate-dependent model is able to fit the experimental data from the current study and the open literature generally well. The mode II fracture toughness measured from the experiment or deduced from the proposed model can be used in the cohesive element model to predict failure. Good agreement is found between the experimental and numerical results, with a maximum difference of 10%. The numerical analyses indicate crack jump occurs suddenly after the peak load is attained, which leads to the unstable crack propagation seen in the experiment.

• Klíčová slova
• Mode II delamination, carbon/epoxy composite, cohesive zone model, displacement rate, fractography,
• Publikační typ
• časopisecké články MeSH