Artificial Neural Networks in Modeling of Dewaterability of Sewage Sludge

Mechanical dewatering is a key process in the management of sewage sludge. However, the drainage efficiency depends on a number of factors, from the type and dose of the conditioning agent to the parameters of the drainage device. The selection of appropriate methods and parameters of conditioning and dewatering of sewage sludge is the task of laboratory work. This work can be accelerated through the use of artificial neural networks (ANNs). The paper discusses the possibilities of using ANNs in predicting the dewatering efficiency of physically conditioned sludge. The input variables were only four parameters characterizing the conditioning methods and the dewatering method by centrifugation. These were the dose of the sludge skeleton builders (cement, gypsum, fly ash, and liquid glass), sonication parameters (sonication amplitude and time), and relative centrifugal force. Dewatering efficiency parameters such as sludge hydration and separation factor were output variables. Due to the nature of the research problem, two nonlinear networks were selected: a multilayer perceptron and a radial neural network. Based on the results of the prediction of artificial neural networks, it was found that these networks can be used to forecast the effectiveness of municipal sludge dewatering. The prediction error did not exceed 1.0% of the real value. ANN can therefore be useful in optimizing the dewatering process. In the case of the conducted research, it was the optimization of the sludge dewatering efficiency as a function of the type and parameters of conditioning factors. Therefore, it is possible to predict the dewatering efficiency of sludge that has not been tested in the laboratory, for example, with the use of other doses of physical conditioner. However, the condition for correct prediction and optimization was the use of a large dataset in the neural network training process.

An important source of preanalytical error in medical laboratories: centrifugation

Centrifugation separates particles within the specimen according to their shape, dimensions, and density and basically can be defined as a separation method. The centrifuge is an essential device in medical laboratories to prepare the serum, plasma, and urine samples for analysis. It is basically an electric device composed of the stationary (motor) and the motile (rotor) part. The centrifugation depends on two main variables: relative centrifugal force (RCF) and centrifugation time. The physical impact separating the specimen into its components in the centrifuge known as RCF is expressed as the multiples of gravitational acceleration (×g). RPM, defined as the number of rotations of the centrifuge per minute, shows the speed of the centrifuge. RCF value can be calculated by using RPM, and the centrifuge radius. Because models and sizes of centrifuges vary considerably, the use of gravity (g) forces instead of RPM is suggested. The centrifuges can be classified according to their usage, speed, technical specifications, and rotor type. An accurate and precise centrifugation process is essential to prevent errors in the preanalytical phase. The purpose of this document is to ensure the standardization of a good, precise protocol for the centrifugation process among the medical laboratories.

Evaluation of 24 protocols for the production of platelet-rich fibrin

Background The aim of this study was to evaluate 24 protocols for the production of platelet rich fibrin (PRF) produced via horizontal centrifugation to better understand cell separation following protocols at various times and speeds. Methods All protocols were compared utilizing a recent method to quantify cells in PRF in 1 mL sequential layers pipetted from the upper layer downwards until all 10 mL were harvested. In total, 960 complete blood counts (CBCs) were investigated. Both solid and liquid-based PRF protocols were investigated following 24 protocols involving 6 relative centrifugal force (RCF) values (100, 200, 400, 700, 1000 and 1200g) at 4 centrifugation times (3, 5, 8 and 12 min). Results In general, platelets could more easily accumulate in the upper 4 layers when compared to leukocytes owing to their lower cellular density. Protocol time seemed to have a greater impact on the final cell layer separation when compared to the effect of speed. Protocols of greater than 8 min at 400g led to no leukocyte accumulation in the upper PRF layers (found specifically within the buffy coat). Protocols at or below 200g were unable to effectively accumulate platelets/leukocytes. The optimal centrifugation speed and time for solid-PRF ranged between 400 and 700g for 8 min. It was noted that variability in patient baseline platelet/leukocyte/erythrocyte counts (hematocrit) significantly affected cell layer separation. This finding was more pronounced at lower centrifugation speeds. Conclusions Within the investigated ranges, a protocol of 700g for 8 min presented the highest yield of platelets/leukocytes evenly distributed throughout the upper PRF layers.

Histological characteristics of Platelet-Rich Fibrin clots obtained under various modes of blood centrifugation

Autologous products of the first and second generation, namely platelet-rich plasma and platelet-rich fibrin, are considered promising for regenerative medicine. They differ from each other in physical properties, as well as in the way they are obtained. The key procedure of all techniques is centrifugation; changing its parameters affects the biological properties of these biomaterials. The aim of the work is to determine and histologically characterize the area of concentration cells of autologous fibrin enriched with platelets, depending on the change in centrifugation parameters. The studies were carried out on rabbits. Blood was collected and platelet-rich plasma (PRP) and platelet-rich fibrin (PRF) were obtained using different values of relative centrifugal force: 100 g, 400 g, 735 g, 906 g, 1843 g. Due to the fact that it is impossible to determine the number of platelets in PRF clots, the counting was performed in platelet-rich plasma obtained by a single centrifugation with the corresponding parameters that were used to obtain PRF. The length of the formed clots was compared and a histological assessment of the cell composition in different layers (lower, middle and upper) was carried out. The highest platelet concentrations were observed in PRP obtained at 100 g and 400 g. Application of different values of centrifugal force showed obvious differences in the formation of platelet-rich fibrin clots. After preparation of I-PRF, its volume was significantly less than that of standard PRF, and the border between erythrocytes was less distinct. During the histological examination of fibrin clots, a change in the distribution of cellular elements in different parts was found with a change in the centrifugation parameters. With an increase in the parameter of relative centrifugal force, the length of the fibrin clot significantly increases, but the concentration of platelets in it significantly decreases. That is, it was found that the most optimal value of the relative centrifugal force for obtaining platelet mass is 100 g, which makes it possible to achieve the number of platelets greater than 800×109/L.

Relative Centrifugal Force (RCF; G-Force) Affects the Distribution of TGF-β in PRF Membranes Produced Using Horizontal Centrifugation

Solid platelet-rich fibrin (PRF) is produced with centrifugation tubes designed to accelerate clotting. Thus, activated platelets may accumulate within the fibrin-rich extracellular matrix even before centrifugation is initiated. It can thus be assumed that platelets and their growth factors such as transforming growth factor-β (TGF-β) are trapped within PRF independent of their relative centrifugal force (RCF), the gravitation or g-force. To test this assumption, we prepared PRF membranes with tubes where clotting is activated by a silicone-coated interior. Tubes underwent 210 g, 650 g and 1500 g for 12 min in a horizontal centrifuge. The respective PRF membranes, either in total or separated into a platelet-poor plasma and buffy coat fraction, were subjected to repeated freeze-thawing to prepare lysates. Gingival fibroblasts were exposed to the PRF lysates to provoke the expression of TGF-β target genes. We show here that the expression of interleukin 11 (IL11) and NADPH oxidase 4 (NOX4), and Smad2/3 signaling were similarly activated by all lysates when normalized to the size of the PRF membranes. Notably, platelet-poor plasma had significantly less TGF-β activity than the buffy coat fraction at both high-speed protocols. In contrast to our original assumption, the TGF-β activity in PRF lysates produced using horizontal centrifugation follows a gradient with increasing concentration from the platelet-poor plasma towards the buffy coat layer.

Evaluation of 24 protocols for the production of platelet-rich fibrin

Background: The aim of this study was to evaluate 24 protocols for the production of platelet rich fibrin (PRF) produced via horizontal centrifugation to better understand cell separation following protocols at various times and speeds. Methods: All protocols were compared utilizing a recent method to quantify cells in PRF in 1 mL sequential layers pipetted from the upper layer downwards until all 10 mL were harvested. In total, 960 complete blood counts (CBCs) were investigated. Both solid and liquid-based PRF protocols were investigated following 24 protocols involving 6 relative centrifugal force (RCF) values (100,200,400,700,1000 and 1200g) at 4 centrifugation times (3,5,8 and 12 minutes). Results: In general, platelets could more easily accumulate in the upper 4 layers when compared to leukocytes owing to their lower cellular density. Protocol time seemed to have a greater impact on the final cell layer separation when compared to the effect of speed. Protocols of greater than 8 minutes at 400 g led to no leukocyte accumulation in the upper PRF layers (found specifically within the buffy coat). Protocols at or below 200 g were unable to effectively accumulate platelets/leukocytes. The optimal centrifugation speed and time for solid-PRF ranged between 400-700 g for 8 minutes. It was noted that variability in patient baseline platelet/leukocyte/erythrocyte counts (hematocrit) significantly affected cell layer separation. This finding was more pronounced at lower centrifugation speeds. Conclusions: Within the investigated ranges, a protocol of 700 g for 8 minutes presented the highest yield of platelets/leukocytes evenly distributed throughout the upper PRF layers.

Evaluation of 24 protocols for the production of platelet-rich fibrin

Background The aim of this study was to evaluate 24 protocols for the production of platelet rich fibrin (PRF) produced via horizontal centrifugation to better understand cell separation following protocols at various times and speeds. Methods All protocols were compared utilizing a recent method to quantify cells in PRF in 1 mL sequential layers pipetted from the upper layer downwards until all 10 mL were harvested. In total, 960 complete blood counts (CBCs) were investigated. Both solid and liquid-based PRF protocols were investigated following 24 protocols involving 6 relative centrifugal force (RCF) values (100,200,400,700,1000 and 1200g) at 4 centrifugation times (3,5,8 and 12 minutes). Results In general, platelets could more easily accumulate in the upper 4 layers when compared to leukocytes owing to their lower cellular density. Protocol time seemed to have a greater impact on the final cell layer separation when compared to the effect of speed. Protocols of greater than 8 minutes at 400 g led to no leukocyte accumulation in the upper PRF layers (found specifically within the buffy coat). Protocols at or below 200 g were unable to effectively accumulate platelets/leukocytes. The optimal centrifugation speed and time for solid-PRF ranged between 400 -700 g for 8 minutes. It was noted that variability in patient baseline platelet/leukocyte/erythrocyte counts (hematocrit) significantly affected cell layer separation. This finding was more pronounced at lower centrifugation speeds. Conclusions Within the investigated ranges, a protocol of 700 g for 8 minutes presented the highest yield of platelets/leukocytes evenly distributed throughout the upper PRF layers.

Evaluation of 24 protocols for the production of platelet-rich fibrin

Background The aim of this study was to evaluate 24 protocols for the production of platelet rich fibrin (PRF) produced via horizontal centrifugation to better understand cell separation following protocols at various times and speeds. Methods All protocols were compared utilizing a recent method to quantify cells in PRF in 1 mL sequential layers pipetted from the upper layer downwards until all 10 mL were harvested. In total, 960 complete blood counts (CBCs) were investigated. Both solid and liquid-based PRF protocols were investigated following 24 protocols involving 6 relative centrifugal force (RCF) values (100,200,400,700,1000 and 1200g) at 4 centrifugation times (3,5,8 and 12 minutes). Results In general, platelets could more easily accumulate in the upper 4 layers when compared to leukocytes owing to their lower cellular density. Protocol time seemed to have a greater impact on the final cell layer separation when compared to the effect of speed. Protocols of greater than 8 minutes at 400 g led to no leukocyte accumulation in the upper PRF layers (found specifically within the buffy coat). Protocols at or below 200 g were unable to effectively accumulate platelets/leukocytes. The optimal centrifugation speed and time for solid-PRF ranged between 400 -700 g for 8 minutes. It was noted that variability in patient baseline platelet/leukocyte/erythrocyte counts (hematocrit) significantly affected cell layer separation. This finding was more pronounced at lower centrifugation speeds. Conclusions Within the investigated ranges, a protocol of 700 g for 8 minutes presented the highest yield of platelets/leukocytes evenly distributed throughout the upper PRF layers.

Evaluation of 24 protocols for the production of platelet-rich fibrin

Background The aim of this study was to evaluate 24 protocols for the production of platelet rich fibrin (PRF) produced via horizontal centrifugation to better understand cell separation following protocols at various times and speeds.Methods All protocols were compared utilizing a recent method to quantify cells in PRF in 1 mL sequential layers pipetted from the upper layer downwards until all 10 mL were harvested. In total, 960 complete blood counts (CBCs) were investigated. Both solid and liquid-based PRF protocols were investigated following 24 protocols involving 6 relative centrifugal force (RCF) values (100,200,400,700,1000 and 1200g) at 4 centrifugation times (3,5,8 and 12 minutes).Results In general, platelets could more easily accumulate in the upper 4 layers when compared to leukocytes owing to their lower cellular density. Protocol time seemed to have a greater impact on the final cell layer separation when compared to the effect of speed. Protocols of greater than 8 minutes at 400 g led to no leukocyte accumulation in the upper PRF layers (found specifically within the buffy coat). Protocols at or below 200 g were unable to effectively accumulate platelets/leukocytes. The optimal centrifugation speed and time for solid-PRF ranged between 400 -700 g for 8 minutes. It was noted that variability in patient baseline platelet/leukocyte/erythrocyte counts (hematocrit) significantly affected cell layer separation. This finding was more pronounced at lower centrifugation speeds.Conclusions Within the investigated ranges, a protocol of 700 g for 8 minutes presented the highest yield of platelets/leukocytes evenly distributed throughout the upper PRF layers.