Changes In Turbidity Research Articles

Approbation of the texture analysis imaging technique in the wastewater treatment plant

AbstractMonitoring of effluent turbidity is essential to evaluate the coagulation process in wastewater treatment plants (WWTPs). A digital imaging system based on the texture analysis of flocs has been tested in a Norwegian municipal WWTP to predict changes in coagulation conditions and outlet turbidity. Principal component analysis (PCA) was applied to prove that the textural features of flocs’ images depend on the inlet wastewater parameters and coagulation conditions. Partial least squares regression (PLSR) was performed for the outlet turbidity prediction. The best model resulted in 86.6 % prediction accuracy using two wastewater quality parameters (inlet flow and inlet turbidity) and four textural feature vectors retrieved from the images of flocs. Furthermore, the outlet turbidity predicted by this model resulted in a lower amount of underestimated values compare to the model, which contained only wastewater quality parameters. A new term – floc texture index (FTI) summarizes the textural features ...

The influence of hydraulic conditions on coagulation process effectiveness

This paper presents the impact that small changes in the hydraulic installation between the flocculation chamber and the sedimentation tanks have on coagulation process effectiveness. This study has shown significant improvements in the parameters of the treated water. The research was conducted in two treatment systems: reference and test, in order to compare the changes that were introduced in the time period between January and May 2016. The hydraulic conditions between the flocculation chamber and the sedimentation tank were changed in the test system, leaving the reference system unchanged for comparative purposes. The height-wise positioning of the sedimentation tank relative to the flocculation chamber resulted in a formation of a cascade at the flocculation chamber drain at a height of 0.60m. Air was therefore introduced into the water, forming an air-water mixture, which disturbed the flow between the devices. It was found that floc transported by the pipeline was broken down, which hampered sedimentation in the sedimentation tank. This was confirmed by the analysis of chosen parameters from treated water. After changes in the hydraulic system, changes in water turbidity were noticed, indicating an increase in post-coagulation suspension separation effectiveness. Consequently, an increase in organic carbon removal was found relative to the reference system. This change influenced changes in UV 254 absorbance to a much lesser extent.

2015~2016年洱海水质参数季节性变化

随着洱海流域建设和生产、生活规模的快速扩展，对洱海水质的影响也日益增强。为了解和认识其水质现状和变化过程，我们对洱海进行了定位水质监测。通过对监测数据分析结果表明：洱海的湖水受到风浪的强烈影响，较浅的南部湖区混合度>北部湖区>中部湖区。作为高原浅水湖泊，洱海不存在温度分层现象，但是7月份在中部湖区与北部湖区出现温跃层和湖上层的混合现象；水温的季节变化影响叶绿素a的变化，较浅的南部湖区更易受到人类活动与自然因素(如风力、吹程、湖流)等多重影响；洱海水体的溶解氧含量存在季节变化，表现为1月份高而7月低；洱海的pH值季节性差异较明显，就监测月份而言，1月份的pH最低，pH值易受水生动植物的光合作用和呼吸作用的影响，7月在湖泊水体中波动较大；洱海水体10月份的叶绿素a浓度、溶解氧浓度和pH值之间均存在显著的相关性；洱海水体中的浊度在季节性变化中受水体深度以及浮游动植物量的影响较大。洱海不同湖区水体的温度(Temp)、叶绿素-a (Chll-a)、溶解氧(DO)、pH以及浊度(Turbid+)的季节性(1月、4月、7月和10月)变化特征显著，并存在明显的空间异质性，结合总氮和总磷数据进行营养化评估，结果显示洱海处于中营养化阶段。 Along with the regional economic development and urban expansion in the Erhai drainage area, the water quality of Lake Erhai has been impacted strongly. To understand the water quality status and its change processes, we have monitored the lake water recently. The analyses results of the monitoring data show that the mixedness of lake water, which is affected by the strong wind and waves in the Lake Erhai, is the highest in the south of lake where with a shallow water depth, and is the lowest in central part of lake, while it shows a moderate situation in the north of the lake. As one of the typical plateau-type shallow lakes, there is no temperature stratification observed in Lake Erhai, but a weak mixing phenomenon between thermocline and epilimnion exist in the central and north part of the lake in July. The seasonal water temperature changes affect the distribution and content of chlorophyll-a, which is also affected by human activity induced nutrient inputs, especially in the shallow area in south of the Lake Erhai, where is more sensitive to natural factors, such as wind velocity, direction and lake current. The dissolved oxygen (DO) content is not only influenced by the algae in lake water, but also the discharge of rivers into the lake. Our monitoring data reveal a seasonal variation of the DO contents, and show a highest value in January high and a lowest value in July. At the same time, the pH value shows a distinguishable seasonal variation with a lowest value in January. As pH is very sensitive to the photosynthesis and respiration of aquatic animals and plants in the lake water, it varies from one area to another abruptly in July. It has been noticed that a strong correlation exist between the chlorophyll-a content, DO and pH values in October. The seasonal change of turbidity is sensitive to water depth and zooplankton and phytoplankton amounts. The total contents of both Nitrogen (TN) and Phosphorous (TP) reveal that Lake Erhai is approaching to the middle to middle-high eutrophication situation, and strong measurements to prevent the lake from further eutrophication is necessary.

Physical compatibility of ceftolozane-tazobactam with selected i.v. drugs during simulated Y-site administration.

Results of a study to examine the physical compatibility of ceftolozane-tazobactam with common i.v. medications during simulated Y-site administration are presented. Ceftolozane-tazobactam was reconstituted according to manufacturer recommendations and diluted with 0.9% sodium chloride or 5% dextrose to solutions containing 15 mg (10 mg of ceftolozane and 5 mg of tazobactam)/mL. All other i.v. drugs were prepared according to manufacturer recommendations and diluted with 0.9% sodium chloride or 5% dextrose to standard concentrations used clinically. Y-site administration was simulated by mixing ceftolozane-tazobactam solution with each tested drug solution at a 1:1 ratio. Solutions were inspected for visual, turbidity, and pH changes immediately and 15, 60, and 120 minutes after mixing. Incompatibility was defined as precipitation, color change, a positive Tyndall test, a change in turbidity of ≥0.5 nephelometric turbidity unit, or a change in pH of ≥1 unit during the 120-minute observation period. Of the 95 i.v. drugs tested, ceftolozane-tazobactam was compatible with 86 drugs in both diluents; notably, it was compatible with metronidazole in both solutions. No substantial pH changes were observed in any tested combination. Ceftolozane-tazobactam was incompatible with albumin, amphotericin B, caspofungin, cyclosporine, nicardipine, and phenytoin sodium due to turbidity changes and with propofol due to formation of an oily layer. Ceftolozane-tazobactam 15 mg (10 mg of ceftolozane and 5 mg of tazobactam)/mL was physically compatible with 86 of 95 study drugs tested in both 0.9% sodium chloride injection and 5% dextrose injection during simulated Y-site administration.

Effect of wave-current interactions on sediment resuspension in large shallow Lake Taihu, China.

The disturbance of the water-sediment interface by wind-driven currents and waves plays a critical role in sediment resuspension and internal nutrient release in large, shallow lakes. This study analyzed the effects of the interactions between wind-induced currents an1d waves on the driving mechanism of sediment resuspension in Lake Taihu, the third largest freshwater lake in China, using acoustic and optic techniques to collect long-term, high-frequency, synchronous in situ measurements of wind, currents, waves, and suspended solid concentrations (SSCs). The results suggested that water turbidity started to increase at wind speeds of approximately 4m/s and significantly increased when wind speeds exceeded 6m/s. In most cases, wind-induced waves were the main energy source for changes in turbidity. Wave-generated shear stress contributed more than 95% to sediment resuspension and that only in weak wind conditions (<4m/s) did the lake bottom shear stresses generated by currents and waves contributed equally. The relationship between SSC and bottom shear stress generated by wave was established by fitting the observed results. The processes of sediment dynamics were divided into four stages (A through D) according to three shear-stress thresholds. In stage A, SSC remained stable (about 45mg/L) and τw was less than 0.02N/m2. In stage B, the sediment bed was starting to be activated (SSC 45∼60mg/L) and τw was in the range of 0.02∼0.07N/m2. In stage C, a medium amount of sediment was suspended (SSC 60∼150mg/L) and τw ranged from 0.07 to 0.3N/m2. In stage D, large amount of sediment was suspended (SSC 150∼300mg/L) and τw was larger than 0.3N/m2. The findings of this paper reveal the driving mechanism of sediment resuspension, which may further help to evaluate internal nutrient release in large shallow Lake Taihu.

Functional and rheological properties of cold plasma treated rice starch

The present work deals with aimed to study the effect of cold plasma treatment on the functional and rheological properties of rice starch using two different power levels (40 and 60W). The changes in amylose content, turbidity, pH, water and fat absorption due to plasma treatment were evaluated. Where decrease in the turbidity and pH after the treatment was observed. Gel hydration properties and syneresis study revealed that there is an increase in leaching of amylose molecules after the treatment. Rapid Visco Analyzer examination showed an increase in pasting and final viscosities. From G′ and G″ moduli determination we observed that there is decrease in retrogradation tendency of starch gels. XRD did not show any change in A-type pattern but decrease in the relative crystallinity was observed due to depolymerization caused by active plasma species. FTIR shows some of the additional functional groups after treatment. SEM showed formation of fissures on the surface of starch granules due to etching caused by the plasma species. Thus, plasma treatment can be one of the methods for physical modification of starch.

Modelling the sensitivity of suspended sediment profiles to tidal current and wave conditions

Seawater turbidity due to suspended particulate material (SPM) is an important property of a marine ecosystem, determining the underwater light environment and many aspects of biological production and ecology. SPM concentrations are largely determined by patterns of sediment resuspension from the seabed due to shear stress caused by waves and currents. Hence planning for the construction of large scale offshore structures which will alter regional hydrodynamics needs to consider the consequences for SPM concentrations. Here we develop a one-dimensional (vertical) model of SPM dynamics which can be used to scope the effects of changes in wave and tidal current properties at a site. We implement the model for a number of sites off the east coast of Scotland where we have extensive data sets to enable numerical parameter optimisation. The model performs well at simulating fluctuations in turbidity varying from flood-ebb tidal cycles, spring-neap cycles, storm wave events, and an annual cycle of SPM concentration which is attributed to seasonal consolidation of seabed sediments. Sensitivity analysis shows that, for the range of seabed sediment types in the study (water depth 16–50 m; mud content 0.006–0.380 proportion by weight), relatively large (50%) attenuations of tidal current speed are required to produce changes in water column turbidity which would be detectable by observations given the variability in measurements. The model has potential for application to map the large scale sensitivity of turbidity distributions to the installation of wave and tidal energy extraction arrays.

The Relationship between the Health of Coral Reefs to The Damages of Jelateng Sub Watersheds in the Northern Coast of Sekotong, West Nusa Tenggara

Coral reefs are unique ecosystem and most of them are found in tropical areas. Remote sensing technology has the ability to present the information about the existence of marine resources, such as coral reefs. Remote sensing technology also provide the spatial information on wider area. This study is aimed to see how significant the effect of watersheds damage toward the condition of coral reefs because of erosion which is occurred in the upstream and sedimentation which is occurred in the downstream of the watershed. Acquisition of the data in this study used remote sensing image Landsat 7 ETM+ and Lansat 8 OLI in multi temporal, the data collection of this study used photo-quadrate technique and taking sample in the field. Spectral analysis and transformation of CTA (Classification Tree Analysis) was used to generate the level of the health of coral reefs. The method of RSI (Red Silt Index) was used to find out the degree of turbidity of the water. Analysis of the changes was done to find out the changes which were occurred on coral reefs based on the changes of turbidity that were occurred between 2000 till 2015. Based on the result, it shows that there is no effect on the changes of turbidity value toward the health condition of coral reefs in the northern coast of Sekotong Sub District 2000 till 2015. This is due to the use of RSI index or turbidity index that cannot be used in the condition of shallow water.

Influence of temperature and turbidity on water COD detection by UV absorption spectroscopy

Ultraviolet (UV) absorption spectroscopy is used to detect the concentration of water chemical oxygen demand (COD). The UV absorption spectra of COD solutions are analyzed qualitatively and quantitatively. The partial least square (PLS) algorithm is used to model COD solution and the modeling results are compared. The influence of environmental temperature and turbidity is analyzed. These results show that the influence of temperature on the predicted value can be ignored. However, the change of turbidity can affect the detection results of UV spectra, and the COD detection error can be effectively compensated by establishing the single-element regression model.

Rapid Screening of Calcium Carbonate Precipitation in the Presence of Amino Acids: Kinetics, Structure, and Composition

Soluble additives are widely used to control crystallization, leading to a definition of properties including size, morphology, polymorph, and composition. However, because of the number of potential variables in these experiments, it is typically extremely difficult to identify reaction conditions—as defined by solution compositions, temperatures, and combinations of additives—that give the desired product. This article introduces a high-throughput methodology which addresses this challenge and enables the streamlined preparation and characterization of crystalline materials. Using calcium carbonate precipitated in the presence of selected amino acids as a model system, we use well plates as microvolume crystallizers, and an accurate liquid-handling pipetting workstation for sample preparation. Following changes in the solution turbidity using a plate reader delivers information about the reaction kinetics, while semiautomated scanning electron microscopy, powder X-ray diffraction, and Raman microscopy p...

Kinetics on the turbidity change of wheat starch during its retrogradation.

Wheat starch dispersions of 10-40% (w/w) were gelatinized and the change in turbidity of each solution during storage was measured in the 400-1100nm wavelength range. The relative transmittance, defined as the ratio of transmittance at any storage time to that at the initial time, decreased when the solutions were stored at 5 and 30°C; the decrease, reflecting the progress of retrogradation, was larger at 5°C than at 30°C. Most of the changes in relative transmission taking place over 14days were achieved during the first 90min. The change in the relative transmittance is inversely proportional to the energy required for deformation. The kinetics on change in relative transmittance can be expressed by Weibull equation. The larger rate constant at higher starch concentration could be ascribed to the state of the starch granules, which depended on starch concentration.

Effect of substituted hydroxyl groups in the changes of solution turbidity in the oxidation of aromatic contaminants.

This paper deals with the changes of turbidity that are generated in aqueous solutions of phenol when they are oxidized by using different Fenton technologies. Results revealed that if the Fenton reaction was promoted with UV light, the turbidity that was generated in the water doubled. Alternatively, the use of ultrasonic waves produced an increase in turbidity which initially proceeded slowly, reaching intensities eight times higher than in the conventional Fenton treatment. As well, the turbidity showed a high dependence on pH. It is therefore essential to control acidity throughout the reaction. The maximum turbidity was generated when operating at pH=2.0, and it slowly decreased with increasing to a value of pH=3.0, at which the turbidity was the lowest. This result was a consequence of the presence of ferric ions in solution. At pH values greater than 3.5, the turbidity increased almost linearly until at pH=5.0 reached its maximum intensity. In this range, ferrous ions may generate an additional contribution of radicals that promote the degradation of the phenol species that produce turbidity. Turbidity was enhanced at ratios R=4.0mol H2O2/mol C6H6O. This value corresponds to the stoichiometric ratio that leads to the production of turbidity-precursor species. Therefore, muconic acid would be a species that generate high turbidity in solution according to its isomerism. Also, the results revealed that the turbidity is not a parameter to which species contribute additively since interactions may occur among species that would enhance their individual contributions to it. Analyzing the oxidation of phenol degradation intermediates, the results showed that meta-substituted compounds (resorcinol) generate high turbidity in the wastewater. The presence of polar molecules, such as muconic acid, would provide the structural features that are necessary for resorcinol to act as a clip between two carboxylic groups, thus establishing directional hydrogen bonds that would generate an adduct in the 2:2 ratio. In addition, some similarity is observed between the turbidity and the presence of dihydroxybenzoquinone. This molecule has a structure that could establish hydrogen bond links with the carboxylic groups in 1:2 ratio. Such supramolecular structures would possess high molecular weight and robustness that would hinder the passage of light through the water, generating high turbidity.

Effect of anionic surfactants on the stability ratio and electrophoretic mobility of colloidal hematite particles

The effect of anionic surfactants on the charging and aggregation of hematite particles was investigated. Charging behavior was studied by the measurement and analysis of the electrophoretic mobility. The stability ratio of hematite suspension was obtained from the temporal change of turbidity, and the stability ratio was analyzed by the DLVO theory. These experiments were performed as functions of types of surfactant, surfactant dosage, and surfactant chain length. Electrophoretic mobility of bare hematite was positive at pH below 7. The mobility went through zero and became negative with increasing surfactant dosage. Required surfactant concentrations reaching the isoelectric point decreased with increasing the chain length of surfactant. These results are reasonably described by a simple theoretical model. The stability ratio showed the minimum around the isoelectric point. That is, the suspension is destabilized by charge neutralization due to the adsorption of surfactants onto the hematite. Values of the minimum stability ratio in this work were almost unity irrespective of the chain length; the fastest aggregation rate with surfactants equaled the salt-induced rate. Therefore, in the case of ionic-surfactant, charge-patch attraction and steric hindrance do not significantly work around zero mobility concentration. The DLVO theory qualitatively describes the aggregation behavior. The range of the minimum stability ratio was narrower for the suspension with fatty acids. This result indicates that the suspension with fatty acids is more stable.

Study of the paracetamol degradation pathway that generates color and turbidity in oxidized wastewaters by photo-Fenton technology

Abstract This study aims determining the effect that certain kind of water contaminants have on the changes of turbidity during their oxidation. Phenol is considered by its frequent presence in industrial discharges; meanwhile paracetamol is representative of emerging pollutants of pharmaceutical origin. Quite different results are observed in the turbidity changes during the oxidation of both pollutants that evolve following the kinetics of a reaction intermediate. The analysis of paracetamol and phenol degradation pathways reveals that operating conditions are important in the formation of intermediates that cause turbidity. The maximum turbidity levels are achieved operating at the ratios 12 mol HO per 100 mg contaminant. However the turbidity generated during the paracetamol oxidation only reaches a third of the intensity achieved with phenol. During the paracetamol degradation, the intermediates causing turbidity are similar to the ones found during the phenol decomposition. These species are generated during the initial minutes of oxidation and possess structures of large size and molecular weight. At the maximum turbidity point, muconic acid and hydroquinone are identified and found to coexist with other compounds such as pyrogallol and resorcinol. Therefore, the path involving metasubstitution would be the main originator of turbidity. It is noteworthy the rapid formation of muconic acid that coexists with resorcinol-like species. These compounds enable the establishment of hydrogen bond interactions that yield supramolecular structures.

Changes in Turbidity, Zeta Potential and Precipitation Yield Induced by Persian Gum-Whey Protein Isolate Interactions During Acidification

To measure the molecular parameters of Persian gum (PG) (gathered from Kazeroon plains/Iran) by gel permeation chromatography-multiangle laser light scattering (GPC-MALLS), water-insoluble part of gum was removed using filtration method. In the following, acidification of whey protein isolate/PG mixture solutions (pH ∼ 7.00–2.00) at different biopolymer mixing ratio (r = 0.1–10) was induced by HCl, allowing turbidity, zeta potential and precipitation yield determinations. Contrary to previous studies, it was demonstrated that more than 93% of gum is composed of large water-insoluble particles and water-soluble part contains heavy and heterogeneous compounds with high weight-average molecular mass (up to 5.11 × 106 g/mol) and high dispersity index (∼2.54–6.64). Acid titration of the mixtures displayed that the net neutrality shifts to the higher pHs by increasing the mixing ratio, and the charge neutralization occurs at pHs near pHopt as well. Generally, the maximum interaction was found for a 1:1 WPI/PG mixture with the highest liquid precipitate yield achieved at pH 3.4. Practical Application Persian gum exudes from the wild almond tree (Amygdalus scoparia), growing in the Middle East countries. The characteristics of this hydrocolloid highly depend on the color of exudate and region of the tree. As a mixture with gum Arabic, it has wide industrial and pharmaceutical applications due to economic reasons and high functionality. However, very few scientific information about this gum has been already published. Some researchers have displayed the emulsifier, stabilizer and fat replacer ability of this gum. The interaction of PG with other biopolymers such as proteins would be beneficial in food and pharmaceutical applications in the form of gels, microcapsules, etc. In this study, we have measured the water-soluble and insoluble fractions and molecular parameters of PG gathered from Kazeroon plains. To have a basic knowledge for our future investigations on encapsulation ability of PG-WPI complexes, titration method was applied for different PG-WPI admixtures.

Synthesis and Characterization of Tunable Dual‐pH Switchable Zwitterionic Copolymers

A dual‐pH switchable zwitterionic copolymer, poly(2‐(dimethylamino)ethyl methacrylate‐co‐acrylamide‐co‐acrylic acid) (poly(DMAEMA‐co‐AM‐co‐AA)), is synthesized by random copolymerization. Characterized by a sharp change in solution turbidity, the conformation of such polymers in aqueous solutions can be switched at both acidic (low pH) and alkaline (high pH) conditions, with the switching pH being finely tunable by controlling the molar ratio of cationic and anionic functional groups of the copolymer. Study with quartz crystal microbalance with dissipation confirm the origin of the conformational change from electrostatic attractions between cationic DMAEMA and anionic AA functional groups. image

Fracture and Growth Are Competing Forces Determining the Fate of Conformers in Tau Fibril Populations

Tau fibrils are pathological aggregates that can transfer between neurons and then recruit soluble Tau monomers by template-assisted conversion. The propagation of different fibril polymorphs is thought to be a contributing factor to phenotypic diversity in Alzheimer disease and other Tauopathies. We found that a homogeneous population of Tau fibrils composed of the truncated version K18 (residues 244–372) gradually converted to a new set of fibril conformers when subjected to multiple cycles of seeding and growth. Using double electron-electron resonance (DEER) spectroscopy, we observed that the distances between spin labels at positions 311 and 328 in the fibril core progressively decreased. The findings were corroborated by changes in turbidity, morphology, and protease sensitivity. Fibrils that were initially formed under stirring conditions exhibited an increased fragility compared with fibrils formed quiescently after multiple cycles of seeding. The quiescently formed fibrils were marked by accelerated growth. The difference in fragility and growth between the different conformers explains how the change in incubation condition could lead to the amplification of a minor subpopulation of fibrils. Under quiescent conditions where fibril breakage is minimal, faster growing fibrils have a selective advantage. The findings are of general importance as they suggest that changes in selective pressures during fibril propagation in the human brain could result in the emergence of new fibril conformers with varied clinicopathological consequences.

Aggregation of Phospholipid Based Vesicle Using Triblock Polymer

ABSTRACTThe motivation of this study is to learn more about the effect of lipid to polymer ratios on the biosensing platform in lipid-based vesicles. Nanoparticles are useful because of their ability to detect cancer in the body with the aid of antibodies. This early detection is crucial in avoiding the rapid spread of tumors. In this study, nanoparticles were synthesized for bio-sensing applications. This was accomplished by combining a long chain lipid (dipalmitoyl-sn-glycero-3-phosphocholine, DPPC) and a short chain lipid (diheptanoyl-sn-glycero-3-phosphocholine, DHPC). After this, the nanoparticles underwent a temperature cycling procedure. Next, the nanoparticles went through a 100nm extrusion filter. This transformed the multilamellar vesicles (MLVs) into unilamellar vesicles (ULVs). The polymer (polypropylene oxide - polyethylene oxide - polypropylene oxide) was then added to the samples, which served as a linker to create a cluster of ULVs. The clustering process was monitored using apparent UV absorption and dynamic light scattering. Dynamic light scattering reflects the hydrodynamic radius of the particle and UV absorption records the change in turbidity. If large clusters are formed, then both the UV absorption and the hydrodynamic radius will increase. Three different polymer to lipid ratios were used: 2.5:1, 1:1, and 0.5:1. The results show that with an increase of polymer to lipid ratios, the aggregation process was facilitated. The nanoparticles were fabricated at the Self-Assembled Functional Nanomaterials (SAFN) lab under the mentorship of Professor Mu-Ping Nieh. The results of this study could provide a more effective way to detect malignant cancer cells in susceptible patients.

Application of sepiolite in clarification of pomegranate juice: changes on quality characteristics during process

SummaryIn this study, for the first time, the function of acid‐activated sepiolite clay was evaluated for clarification of pomegranate juice. The optimum conditions of clarification process were achieved using response surface methodology based on juice turbidity as a response. After that, under optimal condition, efficiency of sepiolite, bentonite and combination of these fining agents with gelatin and kieselgel was compared for clarifying pomegranate juice. The results showed that the best conditions for juice clarification were 0.05% (w/v) clay concentration, temperature of 50 °C and time of 2 h. The results revealed that treatments of bentonite–gelatin–kieselgel and sepiolite–gelatin–kieselgel were the most active fining agents that their use led to a reduction of 99.7% in turbidity of pomegranate juice. Kinetic study for different features was performed, and the results indicated that rate of changes in turbidity, viscosity, total phenolic contents and colour with time followed first‐, first‐, zero‐ and zero‐order kinetic models, respectively.

Procoagulant changes in fibrin clot structure in patients with cirrhosis are associated with oxidative modifications of fibrinogen

Essentials Patients with cirrhosis have hemostatic changes, which may contribute to a risk of thrombosis. This in vitro study compares clot formation and structure between patients and healthy subjects. Clot formation is delayed in patients; ultimately, however, clot permeability is decreased. The thrombogenic structure of fibrin clots may contribute to the thrombotic risk in cirrhosis. Background and Objectives Patients with cirrhosis can be at risk of thrombotic complications due to an imbalance between hemostatic components. However, little is known on how the disease affects clot generation or how alterations in the structure of fibrin clots may affect the hemostatic function of these patients. Methods We investigated the formation and structure of clots generated with plasma and purified fibrinogen of 42 patients with cirrhosis. Clots generated with plasma and fibrinogen of 29 healthy volunteers were studied for comparison. Clot formation and structure were assessed by turbidity, permeation studies, confocal laser and scanning electron microscopy (SEM). The extent of fibrinogen oxidation was assessed by measuring the carbonyl content of purified fibrinogen samples. Results Tissue factor and thrombin-induced clotting of plasma was delayed in patients. The clotting rate was also decreased, but change in turbidity, fibrin density and fiber thickness were largely comparable to healthy volunteers. Conversely, clot permeability was significantly decreased in patients. When clots were generated with purified fibrinogen, differences in clot formation and structure similar to those in plasma were found. The carbonyl content was increased in patient fibrinogen and correlated with disease severity and clot permeability. Conclusions Delayed clot formation in cirrhosis ultimately results in decreased clot permeability. Similar alterations in clots generated with purified fibrinogen suggest that modifications of the molecule are (partly) responsible. Taken together, these findings are indicative of hypercoagulable features of clots of patients with cirrhosis, which may explain the increased risk of thrombosis associated with this condition.