Comparison of platelet-rich fibrin (PRF) produced using 3 commercially available centrifuges at both high (~ 700 g) and low (~ 200 g) relative centrifugation forces

OBJECTIVES

Platelet-rich fibrin (PRF) has gained tremendous momentum in recent years as a natural autologous growth factor derived from blood capable of stimulating tissue regeneration. Owing to its widespread use, many companies have commercialized various centrifugation devices with various proposed protocols. The aim of the present study was to compare 3 different commercially available centrifuges at both high and low g-force protocols.

MATERIALS AND METHODS

PRF was produced on three commercially available centrifuges including the IntraSpin Device (IntraLock), the Duo Quattro (Process for PRF), and Salvin (Salvin Dental). Two separate protocols were tested on each machine including the original leukocyte and platelet-rich fibrin (L-PRF) protocol (~ 700 RCF max (~ 400 RCF clot) for 12 min) as well as the advanced platelet-rich fibrin (A-PRF+) protocol (~ 200 g RCF max (~ 130 g RCF clot) for 8 min). Each of the tested groups was compared for cell numbers, growth factor release, scanning electron microscopy (SEM) for morphological differences, and clot size (both weight and length/width).

RESULTS

The present study found that PRF clots produced utilizing the low-speed centrifugation speeds (~ 200 g for 8 min) produce clots that (1) contained a higher concentration of evenly distributed platelets, (2) secreted higher concentrations of growth factors over a 10 day period, and (3) were smaller in size. This was irrespective of the centrifugation device utilized and consistently observed on all 3 devices. The greatest impact was found between the protocols utilized (up to a 200%). Interestingly, it was further revealed that the centrifugation tubes used had a much greater impact on the final size outcome of PRF clots when compared to centrifugation devices. It was found that, in general, the Process for PRF tubes produced significantly greater-sized clots when compared to other commercially available tubes. The Salvin Dental tubes also produced significantly greater PRF clots when compared to the IntraLock tubes on each of the tested centrifugation devices.

CONCLUSIONS

The present study demonstrated the reproducibility of a scientific concept (reduction in RCF produces PRF clots with more evenly distributed cells and growth factors) utilizing different devices. Furthermore, (and until now overlooked), it was revealed for the first time that the centrifugation tubes are central to the quality production of PRF. Future research investigating tube characteristics thus becomes critically important for the future optimization of PRF.

CLINICAL RELEVANCE

This is the first study to reveal the marked impact of centrifugation tubes on the final production of PRF. Future study thus becomes markedly important to further optimize the quality of PRF-based matrices. It was further found that little variability existed between the centrifugation devices if optimized centrifugation protocols (lower centrifugation speeds) were utilized.

The effect of sampling procedures and day-to-day variations in metabolomics studies of biofluids

Metabolomics analysis of biofluids is a feasible tool for disease characterization and monitoring due to its minimally invasive nature. To reduce unwanted variation in biobanks and clinical studies, it is important to determine the effect of external factors on metabolic profiles of biofluids. In this study we examined the effect of sample collection and sample processing procedures on NMR measured serum lipoproteins and small-molecule metabolites in serum and urine, using a cohort of men diagnosed with either prostate cancer or benign prostatic hyperplasia. We determined day-to-day reliability of metabolites by systematic sample collection at two different days, in both fasting and non-fasting conditions. Study participants received prostate massage the first day to assess the differences between urine with and without prostate secretions. Further, metabolic differences between first-void and mid-stream urine samples, and the effect of centrifugation of urine samples before storage were assessed. Our results show that day-to-day reliability is highly variable between metabolites in both serum and urine, while lipoprotein subfractions possess high reliability. Further, fasting status clearly influenced the metabolite concentrations, demonstrating the importance of keeping this condition constant within a study cohort. Day-to-day reliabilities were however comparable in fasting and non-fasting samples. Urine sampling procedures such as sampling of first-void or mid-stream urine, and centrifugation or not before sample storage, were shown to only have minimal effect on the overall metabolic profile, and is thus unlikely to constitute a confounder in clinical studies utilizing NMR derived metabolomics.

Plasma Filtration Versus Centrifugation in Pediatric Therapeutic Plasma Exchange: Should the Diagnosis Define the Method?†

Therapeutic plasma exchange (TPE) is used for a variety of illnesses in critically ill pediatric patients. Although both centrifugation and filtration are known to be effective methods, to our knowledge, clinical results for TPE by these methods are not compared in pediatric patient populations. One hundred patients who had TPE for a variety of diagnoses were included in the study. In 55 patients plasma exchange was implemented by centrifugation and in 45, by filtration. These two groups were further divided into subgroups according to admittance diagnoses. The demographic information, admittance Pediatric Risk of Mortality scores, Pediatric Logistic Organ Dysfunction (PELOD) scores before beginning of therapy and PELOD at the end of therapy, durations of ventilatory support, pediatric intensive care unit and hospital stay, and outcomes were compared. Although the survival was significantly better in filtration group, it included more patients with neurologic diagnoses. Filtration group standard mortality rate was 0.6. In both groups, the PELOD scores after the termination of TPE were significantly decreased compared to that before beginning of TPE. Within thrombotic microangiopathy and hemophagocytic lymphohistiocytosis subgroups, median PELOD scores before treatment were higher in centrifugation patients but survival was similar with both methods. Both methods of TPE are alike in decreasing PELOD scores. In the filtration group, survival benefit of TPE is evident. In thrombotic microangiopathy patients, despite higher PELOD scores in the centrifugation group, survival is similar for both methods. These findings should be retested in randomized studies and the underlying physiology awaits to be uncovered.

Cell-Free DNA: An Overview of Sample Types and Isolation Procedures

The study of cell-free DNA (cfDNA) is often challenging due to genomic DNA contamination, low concentration, and high fragmentation. Therefore, it is important to optimize pre-analytical and analytical procedures in order to maximize the performance of cfDNA-based analyses.In this chapter, we report the most common methods for the correct collection, centrifugation, storage, and DNA isolation from cell-free biological sources such as plasma, urines, cerebrospinal fluid, and pleural effusion fluid.

Barricor blood collection tubes are equivalent to PST for a variety of chemistry and immunoassay analytes except for lactate dehydrogenase

INTRODUCTION

The BD Barricor tube uses a novel mechanical separator designed to eliminate gel artifacts, decrease cellular contamination, and improve stability. Here, we evaluated the Barricor tube as a possible replacement for PST using Beckman Coulter analyzers under both optimal, alternative, and suboptimal centrifugation conditions based on BD recommendations.

METHODS

Paired PST and Barricor samples were collected from 4 local hospitals and processed based on site-specific preanalytical systems involving automated or manual centrifugation. Centrifugation conditions ranged from 1912 ×g for 10 min (suboptimal), 2060 g for 10 min (alternative), and 4000 ×g for 3 or 10 min (optimal). Tube volume (4.5 vs. 5.5 ml) was also assessed. Forty-three chemistry and immunochemistry analytes were measured on Beckman Coulter DxC and DxI analyzers.

RESULTS

Using an automated preanlaytical system with suboptimal spin conditions, no bias between PST and Barricor was observed for all analytes tested except lactate dehydrogenase (LD). Further investigation revealed significant increase in LD when Barricor was spun for 10 min at 1912, 2060 and 4000 ×g, ranging from +7.4-19.4% vs. PST across the entire measurement interval (87-493 U/l). Smaller tube volume was also associated with higher LD. Differences in LD occurred despite no change in other hemolysis markers such as potassium, phosphate, and AST.

CONCLUSIONS

LD is most sensitive to varying centrifugation conditions (time and speed) in Barricor tubes. We recommend that BD centrifugation protocols should be closely evaluated to determine if Barricor is equivalent to PST under local preanalytical configurations.

Manufacturing of Proteins and Antibodies: Chapter Downstream Processing Technologies

Cell harvesting is the separation or retention of cells and cellular debris from the supernatant containing the target molecule Selection of harvest method strongly depends on the type of cells, mode of bioreactor operation, process scale, and characteristics of the product and cell culture fluid. Most traditional harvesting methods use some form of filtration, centrifugation, or a combination of both for cell separation and/or retention. Filtration methods include normal flow depth filtration and tangential flow microfiltration. The ability to scale down predictably the selected harvest method helps to ensure successful production and is critical for conducting small-scale characterization studies for confirming parameter targets and ranges. In this chapter we describe centrifugation and depth filtration harvesting methods, share strategies for harvest optimization, present recent developments in centrifugation scale-down models, and review alternative harvesting technologies.

Plasma exchange activity in the European Union

In spite of a relatively high number of diseases where therapeutic plasma exchange (TPE) is recommended as a first (category I) or second line of therapy (category II), according to the Guidelines on the Use of Therapeutic Apheresis in Clinical Practice-Evidence-Based Approach from the American Society for Apheresis, evidence exists that the number of procedures that are performed varies widely depending on the countries and even between centers in a given country. The aim of this work was to analyze the number of TPE that are performed in different European countries and calculate the rate of TPE per 1,000,000 inhabitants. We contacted the three manufacturers of disposables for performing TPE by centrifugation in Europe (Fresenius Kabi, Haemonetics, and Teurmo BCT) and asked them for the number of disposables sold in each of the countries of the European Union (EU) in 2014 as a surrogate indicator of the TPE performed in the country. A total of 101,767 disposable units to perform TPE using centrifugation devices were sold in the EU in 2014. A huge variation exists in the number of disposable units of PTE sold in the different EU countries. A factor of 51 separates the rate of TPE per 1 million inhabitants performed by centrifugation in the country with the highest number (Belgium, 459) from the country with the lowest (Romania, 9). That variation probably is due to differences in healthcare expenditure but also differences in practice.

The influence of centrifugation and incubation temperatures on various veterinary and human chlamydial species

The Chlamydiaceae are Gram-negative bacteria causing diseases in humans and in both, endothermic (mammals and birds) and poikilothermic (e.g. reptiles, amphibians) animals. As most chlamydial species described today were isolated from humans and endothermic animals, the commonly used culturing temperature in vitro is 37 °C, although the centrifugation temperature during experimental infection, a technique necessary to improve the infection rate, may vary from 25 to 37 °C. The aim of this study was to investigate the influence of different centrifugation (28° or 33 °C) and incubation temperatures (28 °C or 37 °C) on the average inclusion size, infectivity and ultrastructural morphology of human and animal chlamydial strains, as well as two recently described species originating from snakes, C. poikilothermis and C. serpentis, in LLC-MK2 cells at 48 h post infection. Infectivity and average inclusion size was reduced at an incubation temperature of 28 °C compared to 37 °C for all strains including C. poikilothermis, although the latter formed larger, fully matured inclusions at 28 °C in comparison to the other investigated Chlamydia species. C.psittaci displayed a shorter developmental cycle than the other species confirming previous studies. Higher centrifugation temperature increased the subsequent inclusion size of C. trachomatis, C. abortus and C. suis but not their infectivity, while the incubation temperature had no discernable effect on the morphology, inclusion size and infectivity of the other chlamydial strains. In conclusion, we found that all Chlamydia species are viable and can grow at low incubation temperatures, although all strains grew better and more rapidly at 37 °C compared to 28 °C.

Morphological and electrical disturbances after split-flow fractionation in murine macrophages

Split-flow fractionation (SPLITT) is a family of techniques that separates in the absence of labeling using very low flow rates and force fields, and is therefore expected to minimize cell damage. Although it has been documented that separation methods cause physiological changes in immune cells that are attributable to mechanical stress and antibody labeling, SPLITT has not yet been examined for possible damaging effects of hydrodynamic stress, partly because it is assumed that the low flow rates and weak forces used in this technique do not generate significant mechanical stress. The aim of this study was to investigate the effects of SPLITT on cell function of a murine macrophage cell, and to compare these effects with those induced by centrifugation. Macrophages J774.2 were cultured in RPMI-enriched media, then detached from the culture flask and resuspended for 12 h. Cell suspensions were diluted in a buffered saline solution and exposed to SPLITT (flow rates 1-10 ml/min) or centrifugation (100-1500g) for 10 min. Cell viability, diameter, membrane potential, and nitric oxide production were measured. Under the operating conditions employed, cell viability was above 98% after SPLITT and centrifugation but cells suffered immediate hydrodynamic cell damage, including decreased cell diameter and membrane hyperpolarization which was inhibitable by 4-aminopyridine; nitric oxide production was not affected. Pressure values during SPLITT and centrifugation correlated with diameter and membrane potential. Our data do not support the assumption that SPLITT is innocuous to cell function. Some changes in SPLITT channel design are suggested to minimize cell damage. Membrane potential and cell diameter are sensitive indicators for the evaluation of sublethal damage in different cell models, and allow identification of optimal operating conditions on different scales.

Direct observation of the cell-wall remodeling in adhering Staphylococcus aureus 27217: An AFM study supported by SEM and TEM

We took benefit from Atomic Force Microscopy (AFM) in the force spectroscopy mode to describe the time evolution – over 24 h – of the surface nanotopography and mechanical properties of the strain Staphylococcus aureus 27217 from bacterial adhesion to the first stage of biofilm genesis. In addition, Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) experiments allowed identifying two types of self-adhering subpopulations (the so-called “bald” and “hairy” cells) and revealed changes in their relative populations with the bacterial culture age and the protocol of preparation. We indeed observed a dramatic evanescing of the “hairy” subpopulation for samples that underwent centrifugation and resuspension processes. When examined by AFM, the “hairy” cell surface resembled to a herringbone structure characterized by upper structural units with lateral dimensions of ∼70 nm and a high Young modulus value (∼2.3 MPa), a mean depth of the trough between them of ∼15 nm and a resulting roughness of ∼5 nm. By contrast, the “bald” cells appeared much softer (∼0.35 MPa) with a roughness one order of magnitude lower. We observed too the gradual detachment of the herringbone patterns from the “hairy” bacterial envelope of cell harvested from a 16 h old culture and their progressive accumulation between the bacteria in the form of globular clusters. The secretion of a soft extracellular polymeric substance was also identified that, in addition to the globular clusters, may contribute to the initiation of the biofilm spatial organization.

Solid alcohol based on waste cooking oil: Synthesis, properties, micromorphology and simultaneous synthesis of biodiesel

Solid alcohols based on waste cooking oil (WCO) and other edible oils (butter or soybean oil) were synthesized by a simple one-step method. The effects of sodium hydroxide (NaOH) dosage and type of oil on the combustion performances were explored. IR spectroscopy and micro-morphologies of the oil based solid alcohols were also studied. Results showed that, for oil based solid alcohol, use of an appropriate excess of NaOH and an oil with lower iodine value produced the solid alcohol with better combustion performance. Centrifugation produced the bottom waste cooking oil (B-WCO) with lower iodine value and the supernatant waste cooking oil (S-WCO) with higher iodine value. The B-WCO afforded solid alcohol with longer combustion time, higher melting temperature and relatively low combustion residue rate, whereas the S-WCO could be used for synthesizing biodiesel.

Primary Recovery of Yeast Culture Supernatant for Recombinant Protein Purification

The harvest of a bench scale high cell density fermentation of Pichia pastoris, using standard laboratory equipment, to process products from supernatant is described. The process consists of a centrifugation step and a depth filtration, followed by a (sterile) membrane filtration. The procedure yields supernatant ready for the next purification step such as chromatography.

Determination of the microplastics emission in the effluent of a municipal waste water treatment plant using Raman microspectroscopy

Samples from the secondary clarifier effluent of a waste water treatment plant (serving 98500 inhabitants) were analyzed to determine the microplastics (MP) emission. The samples were collected using a stainless steel centrifugal pump and filtered through a 10 μm stainless steel cartridge filter. Microplastics particles (MPPs) and microplastics fibers (MPFs) were recovered by chemical and physical sample purification. To remove natural organic matter, the samples were first subjected to oxidative treatment with H₂O₂ and NaClO. Inorganic materials were subsequently removed by density separation in ZnCl₂ (ρ = 1.9 g/cm³) using a centrifuge. Special centrifuge tubes were developed for this purpose. Sample analysis was performed on a Si filter by Raman micro-spectroscopy. Particles with a diameter (d_p) ≥ 10 μm were analyzed. The results were differentiated by dry and wet weather samples. On average, 5900 MPPs m^-3 were identified in the effluent on wet weather days compared to 3000 MPPs m^-3 on dry weather days. Most of the MPPs detected were in the 30 μm < d_p < 100 μm size range. The MPFs ranged between 100 μm and 1000 μm in length. While most of the MPFs were of PET origin, the MPPs consisted mainly of PET, PP, PE and PS.

Composition of acacia honeys following processing, storage and adulteration

This study investigated the effect of different treatments (centrifugation and filtration; heating; adulteration with sugar syrups, and storage) and collection variables (year and region of the country) on the physicochemical properties of 44 Hungarian acacia honeys. The characteristics measured were diastase activity, hydroxyl-methyl-furfural (HMF), total phenolic content (TPC), electrical conductivity (EC), colour, pH, proline, moisture, sucrose, fructose and glucose contents, and concentration of eleven elements (As, B, Cd, Cr, Fe, K, Mg, Na, P, S, Zn). Centrifugation and filtration reduced the concentration of all examined parameters, except for moisture. Heating reduced diastase activity, proline and total phenolic concentrations and increased HMF concentration and colour value. Adulteration with sugar syrups had adverse effects on the diastase activity, proline, moisture and sugar concentrations, EC, colour and pH. Two-year storage reduced diastase activity, HMF, proline and TPC concentrations and increased sucrose concentrations. The collecting area influenced Na, Fe and As concentration, but the collecting year had no effect on the examined parameters. It is concluded that method and region of honey collection, duration of storage and processing all have major effects on the quality of acacia honey. Applied sugar syrup, although it affected honey quality, would be difficult to detect in the finished product.

Biobanking of Cerebrospinal Fluid

Cerebrospinal fluid (CSF) is a physiologically essential fluid produced by the brain that is involved in protecting the brain and in the exchange of nutrients and waste products. CSF has long been utilized to confirm clinical suspicion of various infectious and inflammatory disorders, such as meningitis and multiple sclerosis. However, there has been increasing interest in collecting CSF in order to study the clinical significance of additional biomarkers. This chapter outlines the procedures necessary to collect, process, store, and utilize CSF obtained for the purposes of biobanking from both living and deceased patients.

Multiscale analysis of architecture, cell size and the cell cortex reveals cortical F-actin density and composition are major contributors to mechanical properties during convergent extension

The large-scale movements that construct complex three-dimensional tissues during development are governed by universal physical principles. Fine-grained control of both mechanical properties and force production is crucial to the successful placement of tissues and shaping of organs. Embryos of the frog Xenopus laevis provide a dramatic example of these physical processes, as dorsal tissues increase in Young's modulus by six-fold to 80 Pascal over 8 h as germ layers and the central nervous system are formed. These physical changes coincide with emergence of complex anatomical structures, rounds of cell division, and cytoskeletal remodeling. To understand the contribution of these diverse structures, we adopt the cellular solids model to relate bulk stiffness of a solid foam to the unit size of individual cells, their microstructural organization, and their material properties. Our results indicate that large-scale tissue architecture and cell size are not likely to influence the bulk mechanical properties of early embryonic or progenitor tissues but that F-actin cortical density and composition of the F-actin cortex play major roles in regulating the physical mechanics of embryonic multicellular tissues.

Rapid creation system of morphologically and functionally communicative three-dimensional cell-dense tissue by centrifugation

This study reports a rapid fabrication system of a morphologically and functionally communicative three-dimensional (3D) cell-dense tissue without scaffolds by centrifugation. The tight adhesion between C2C12 myoblasts and culture surface was accelerated without significant cell damage by centrifugation (80 x g, 37 °C, 30 min). A thicker tissue created on a temperature-responsive culture surface was harvested by decreasing temperature. The 3D myoblast tissues having approximately 200 μm-thickness were created at 1.5 h [centrifugation (80 x g, 37 °C) for 30 min and tissue harvest for 1 h]. However, in the case of without centrifugation, the myoblast tissues had fragile parts even at 7.5 h after the incubation. Additionally, electrically/functionally communicative and thicker human induced pluripotent stem (iPS) cell-derived cardiac tissues were created rapidly by the centrifugation and cultivation at 37 °C. We report a centrifugation system that significantly shortens the creation time of 3D tissues. We envision that this procedure will contribute to the field of tissue engineering and regenerative medicine. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:1447-1453, 2018.

Centrifugal dewatering performance in plastic films recycling

Dewatering of plastic films is a highly energy-consuming recycling operation that largely affects the quality of the recycled product. Despite the importance of good drying, this operation has not been studied at laboratory or pilot plant scale. In this work, the mechanical dewatering of blown film grade high density polyethylene has been assessed by using a laboratory centrifuge. It is suggested that a plastic cake is formed under the centrifugal forces similar to the sludge cake after the filtration process. The water is retained within the plastic cake due to three phenomena: free water within the cake pores and voids, water maintained by capillarity (superficial and pendular) and water trapped due to the tortuosity of the plastic mass. The total moisture is a sum of an equilibrium moisture and a transient moisture. The equilibrium moisture depends on the centrifugal force (G) but it is independent of time. Conversely, the transient moisture is reliant on both the G-force and the centrifugation time. The experimental results showed that an optimum side length exists. The moisture content is minimized when the flake side lies between 1 and 2 cm. Finally, it has been found that the moisture content is a function of the plastic surface. Hence, the specific moisture content (the mass of water per total plastic surface) should be calculated to compare films with uneven thickness or made of different materials. In sum, the outcomes of this study may be fundamental for the further and more extensive research into the plastic films dewatering processes.

Dialysis of the goat semen and its effect on the quality of frozen/thawed spermatozoa processed in the presence of egg yolk

The aim of the present study was to analyze the effect of dialysis on the quality of frozen/thawed buck semen. Ejaculates (n = 15) from three Saanen bucks were divided into three experimental groups. Semen in Group Ce (centrifugation) was processed by standard method and washed two times at 1.085 × g for 20 min. During this time, the diluted control semen (Co) was stored at room temperature. Semen in Group D was dialyzed using 300 kDa cut-off semi-permeable cellulose tubing. The semen from all groups was diluted with extender containing 20% egg yolk and frozen in liquid nitrogen vapor. After thawing, semen samples were evaluated by microscopic and biochemical analyses. Phospholipase A2 was in amounts that was 72.0 ± 11.7% less after dialysis and 21.3 ± 10.0% less after washing with centrifugation compared to the control semen (P <  0.05). Spermatozoa from Group Co had a lesser motility and viability and greater percentage of morphological abnormal spermatozoa in comparison to Groups D and Ce at 3 h after thawing and incubation on 37 °C. At the same time motility and percentage of HOST positive spermatozoa were greater in Group Ce compared with D (P <  0.05). There, however, was no difference in morphology and viability (CFDA/PI analysis) of spermatozoa between Ce and D group. Results from the present study suggest the dialysis is the promising alternative method for reducing phospholipase A2 in the buck semen before cryopreservation.

Influence of soil conditions on the distribution coefficients of 226Ra in natural soils

In order to clarify some of the assumptions and approximations about the use of the distribution coefficient K_d for ²²⁶Ra in soils, a systematic study has been performed using centrifugation to extract the soil solution. The separated fractions of the soil solution have different kinetics with respect to the sorption process in the soil, which may in turn condition the final chemical composition and even the speciation of the radionuclides in solution. In the experimental design of this study three factors were considered: the moisture level in the incubation process, incubation time and the speed of centrifugation. Also, three levels were chosen for each factor. In order to analyze the influence of the structural characteristics of the soil, this study was performed with three textural fractions: coarse sand, fine sand, and silt and clay, obtained from an only soil. Also, the soil was naturally enriched with radionuclides of the ²³⁸U series. An analysis of variance (ANOVA) was performed in order to assess the influence of the factors studied on the distribution coefficient of ²²⁶Ra. The results indicate that different behaviors can be observed depending on the structural characteristic of the soil. In the case of particle size, the soil with the largest grain size showed that the incubation process parameters influence the equilibrium level achieved, while in the case of the smallest edaphic particles, radium is not homogeneously distributed in the soil solution and the K_d value is dependent on the speed of centrifugation.

Comparison of Rapid Centrifugation Technique with Conventional Centrifugation for Prothrombin Time (PT) and Activated Partial Thromboplastin Time (APTT) Testing

Prothrombin Time (PT) and activated partial thromboplastin time (APTT) are frequently performed coagulation tests in patients with coagulation disorders especially in critical care areas and in monitoring patients on anticoagulation therapy. In coagulation testing, sample processing especially centrifugation is one of the most critical steps that affect turnaround time (TAT). This study was carried out over a period of 1 year. Three hundred paired samples from patients sent for PT and APTT estimation were included. One sample was centrifuged in a regular bench top centrifuge at 1500g for 20 min. The other sample was divided into two polypropylene aliquots and centrifuged in a microcentrifuge at 13000g for 3 min. The plasma obtained from both methods was tested for PT and APTT using the automated method on STA Compact coagulometer (Stago) using commercial thromboplastin STA^R-Neoplastine^R C1 Plus and phospholipid (cephalin), STA^R-C K PREST^R 5 respectively. Data were analyzed using descriptive statistics, Student t test, correlation coefficient and Bland-Altman plots. Mean PT, INR and APTT for both centrifugation methods was comparable with no statistically significant difference (p > 0.05). PT, INR and APTT also showed good correlation (r > 0.98) when compared between the two methods of centrifugation. Bland-Altman comparison between rapid and conventional methods of centrifugation for PT, INR and APTT also showed acceptable agreement. Rapid centrifugation technique for routine coagulation testing can be used safely with a significant reduction in the TAT. This can benefit patients in critical care settings and those on outpatient oral anticoagulant therapy.

Temperature dependent separation of immiscible polymer blend in a melted state

The density and the spectral fingerprint of a compounded blend or composite vary widely depending on the type of the components and their composition. However, the currently used polymer separation techniques, such as density-based and optical sorting systems are not suitable for recovering these materials fully due to the physical-chemical bonding between the components. The application of a novel separation principle creates the opportunity to enrich the blend fractions to neat, homogeneous zones in a melted state by utilising centrifugal force. In this study three different types of plastics: high density polyethylene, polystyrene and polyethylene terephthalate were deeply investigated in order to understand the separability of their blends as a function of rotation time and melt temperature. The results showed that the separation of polymer mixtures and blends depends strongly on the viscosity and bulk density at a given temperature, and the initial particle size also has a significant impact.

Microalgae harvesting techniques: A review

Microalgae with wide range of commercial applications have attracted a lot of attention of the researchers in the last few decades. However, microalgae utilization is not economically sustainable due to high cost of harvesting. A wide range of solid - liquid separation techniques are available for microalgae harvesting. The techniques include coagulation and flocculation, flotation, centrifugation and filtration or a combination of various techniques. Despite the importance of harvesting to the economics and energy balance, there is no universal harvesting technique for microalgae. Therefore, this review focuses on assessing technical, economical and application potential of various harvesting techniques so as to allow selection of an appropriate technology for cost effectively harvesting of microalgae from their culture medium. Various harvesting and concentrating techniques of microalgae were reviewed to suggest order of suitability of the techniques for four main microalgae applications i.e biofuel, human and animal food, high valued products, and water quality restoration. For deciding the order of suitability, a comparative analysis of various harvesting techniques based on the six common criterions (i.e biomass quality, cost, biomass quantity, processing time, species specific and toxicity) has been done. Based on the order of various techniques vis-a-vis various criteria and preferred order of criteria for various applications, order of suitability of harvesting techniques for various applications has been decided. Among various harvesting techniques, coagulation and flocculation, centrifugation and filtration were found to be most suitable for considered applications. These techniques may be used alone or in combination for increasing the harvesting efficiency.

Microalgae harvesting techniques: A review

Microalgae with wide range of commercial applications have attracted a lot of attention of the researchers in the last few decades. However, microalgae utilization is not economically sustainable due to high cost of harvesting. A wide range of solid - liquid separation techniques are available for microalgae harvesting. The techniques include coagulation and flocculation, flotation, centrifugation and filtration or a combination of various techniques. Despite the importance of harvesting to the economics and energy balance, there is no universal harvesting technique for microalgae. Therefore, this review focuses on assessing technical, economical and application potential of various harvesting techniques so as to allow selection of an appropriate technology for cost effectively harvesting of microalgae from their culture medium. Various harvesting and concentrating techniques of microalgae were reviewed to suggest order of suitability of the techniques for four main microalgae applications i.e biofuel, human and animal food, high valued products, and water quality restoration. For deciding the order of suitability, a comparative analysis of various harvesting techniques based on the six common criterions (i.e biomass quality, cost, biomass quantity, processing time, species specific and toxicity) has been done. Based on the order of various techniques vis-a-vis various criteria and preferred order of criteria for various applications, order of suitability of harvesting techniques for various applications has been decided. Among various harvesting techniques, coagulation and flocculation, centrifugation and filtration were found to be most suitable for considered applications. These techniques may be used alone or in combination for increasing the harvesting efficiency.

Biochemical Properties of Pathology-Related Tau Species in Tauopathy Brains: An Extraction Protocol for Tau Oligomers and Aggregates

Intracellular deposition of microtubule-associated protein tau in the form of filamentous aggregates is a prominent neuropathological feature of neurodegenerative disorders termed tauopathy. Formation of filamentous tau aggregates is presumably initiated by phosphorylation and/or conformational change of protein structure followed by oligomerization and fibril extension. These processes via intermediate oligomers have not yet been entirely resolved. To examine the biochemical properties of tau protein including oligomers, standardized isolation methods will invariably provide molecular mechanisms of tauopathy. In this chapter, we describe the procedures for isolating tau oligomers based on biochemical properties.