Relative Centrifugal Force Research Articles

Response Surface Methodology Optimization of Exosome-like Nanovesicles Extraction from Lycium ruthenicum Murray and Their Inhibitory Effects on Aβ-Induced Apoptosis and Oxidative Stress in HT22 Cells.

Exosome-like nanovesicles (ELNs) derived from plants are nanoscale vesicles isolated from edible plant sources. Lycium ruthenicum Murray (LRM) has garnered growing attention for its dietary value and therapeutic benefits. In this study, a PEG6000-based method was developed to isolate LRM-ELNs. Response surface methodology (RSM) was used to optimize the extraction conditions to obtain the optimal extraction efficiency. When PEG6000 concentration was at 11.93%, relative centrifugal force was 9720 g, and incubation time was 21.12 h, the maximum LRM-ELN yield was 4.24 g/kg. This optimization process yielded LRM-ELNs with a particle size of 114.1 nm and a surface charge of -6.36 mV. Additionally, LRM-ELNs mitigated Aβ-induced apoptosis in HT22 cells by enhancing mitochondrial membrane potential (MMP), lowering the Bax/Bcl-2 ratio, and reducing Cleaved Caspase-3 expression. Furthermore, LRM-ELNs alleviated Aβ-induced oxidative stress in HT22 cells by promoting the nuclear translocation of Nrf2 and upregulating the expression of HO-1 and NQO1. These findings indicate that LRM-ELNs exert protective effects against Aβ-induced damage in HT22 cells and may be considered as a potential dietary supplement for Alzheimer's disease prevention.

Optimizing rare earth element beneficiation using response surface methodology and Knelson concentrator

ABSTRACT The beneficiation of rare earth elements is a crucial process in unlocking the potential of these valuable resources. This study investigates the utilization of response surface methodology in optimizing rare earth beneficiation using a laboratory Knelson concentrator. The experimental design employed response surface methodology to analyze and predict the effects of various parameters, such as feed rate, water pressure, and particle size, on the efficiency of rare earth recovery. Through systematic experimentation and statistical analysis, this research establishes optimal conditions for the Knelson concentrator operation, enhancing the recovery of rare earth elements. The study presents a comprehensive analysis of the impact of individual factors and their interactions on the beneficiation process. The results showed that for −0.5 + 0.074 mm fraction the main influencing factors were in the order of relative centrifugal force > fluidization water flow rate > feeding rate, and the factors acting on −0.074 + 0.02 mm fraction were fluidization water flow rate > relative centrifugal force > feeding rate. The beneficiation performance by Knelson concentrator for −0.074 + 0.02 mm fraction was better than that of −0.5 + 0.074 mm fraction. The findings demonstrate the efficacy of response surface methodology as a tool for optimizing the Knelson concentrator’s performance in rare earth beneficiation. This approach offers insights into process optimization and provides a framework for improving the efficiency of rare earth recovery methods, contributing to the sustainable utilization of these critical elements in various industrial applications.

Platelet rich fibrin as a bioactive matrix with proosteogenic and proangiogenic properties on human healthy primary cells in vitro

Blood concentrates like platelet rich fibrin (PRF) have been established as a potential autologous source of cells and growth factors with regenerative properties in the field of dentistry and regenerative medicine. To further analyze the effect of PRF on bone tissue regeneration, this study investigated the influence of liquid PRF matrices on human healthy primary osteoblasts (pOB) and co-cultures composed of pOB and human dermal vascular endothelial cells (HDMEC) as in vitro model for bone tissue regeneration. Special attention was paid to the PRF mediated influence on osteoblastic differentiation and angiogenesis. Based on the low-speed centrifugation concept, cells were treated indirectly with PRF prepared with a low (44 g) and high relative centrifugal force (710 g) before the PRF mediated effect on osteoblast proliferation and differentiation was assessed via gene and protein expression analyses and immunofluorescence. The results revealed a PRF-mediated positive effect on osteogenic proliferation and differentiation accompanied by increased concentration of osteogenic growth factors and upregulated expression of osteogenic differentiation factors. Furthermore, it could be shown that PRF treatment resulted in an increased formation of angiogenic structures in a bone tissue mimic co-culture of endothelial cells and osteoblasts induced by the PRF mediated increased release of proangiogenic growth factors. The effects on osteogenic proliferation, differentiation and vascularization were more evident when low RCF PRF was applied to the cells. In conclusion, PRF possess proosteogenic, potentially osteoconductive as well as proangiogenic properties, making it a beneficial tool for bone tissue regeneration.

The effect of size and shape of annular centrifugal contactors upon hydrodynamics and mass transfer using HNO3-TBP/OK

Annular centrifugal contactors (ACCs) are process intensification equipment for liquid-liquid extraction (also known as solvent extraction) that use centrifugal force that 200x greater than traditional gravity settling (Baker et al., 2022a). The size and throughput of ACCs have been denoted by their increasing rotor diameter (RD), from 10 mm up to 1330 mm. In this work a multiscale ACC platform has been commissioned, (consisting of 10, 25, 40 mm RD ACCs), to collect the physical liquid-holdup and mass transfer across several sizes to inform future computation modelling flowsheets of liquid-liquid extraction (LLE).Experimental studies have been performed with nitric acid with tributyl phosphate in odourless kerosene (TBP/OK) relevant to the development of advanced PUREX processes for recovery of actinides from spent fuel. Hydrodynamic trials determined the minimum Relative Centrifugal Force (RCF) required to separate extreme solvent/aqueous (S/A) feed ratios and total throughputs across the three sizes of ACC. The novel 'stepped stop' method has provided understanding of the actual liquid holdups within the two distinctly different regions (mixing annulus and separating rotor) ACC during operation to provide accurate residence times. These values were subsequently used to calculate the mass transfer and stage efficiency of aqueous nitric acid with tributyl phosphate in odourless kerosene. The smallest contactor was determined to be distinct and likely under-predicting performance of larger contactors. Ultimately the geometry and the aspect ratio supersedes using rotor diameter for defining scale-up of annular centrifugal contactors.

Clinical and radiographic evaluation of the use of PRF, CGF, and autogenous bone in the treatment of periodontal intrabony defects: Treatment of periodontal defect by using autologous products.

The purpose of this randomized clinical study was to clinically evaluate and compare the efficiencies of platelet-rich fibrin (PRF), concentrated growth factor (CGF) and autogenous bone graft (ABG) in the treatment of intrabony pockets and to assess the alveolar bone gain (AB gain) radiographically (panoramic and CBCT images). Eighty intrabony pockets were divided into four groups: ojnly open flap debridement (OFD), OFD+PRF, OFD+CGF and OFD+ABG; each group consisted of 20 defects. Plaque index (PI), gingival index (GI), probing depth (PD), clinical attachment level (CAL), and tooth mobility (TM) by using Periotest M device were evaluated. Radiographic images were also taken to evaluate the AB gain. PRF was produced using a protocol of 2,700 RPM for 12 min and the relative centrifugal force (RCF) was evaluated. CGF was prepared as follows: 2min 2700rpm, 4min 2400rpm, 4min 2700rpm, 3min 3000rpm. The study results revealed a similar improvement in PI and GI values in all groups (p>0.05). There was a statistically significant decrease in PD and CAL in favor of ABG group at day 180 in comparison with other groups (p=0.001). There was also a statistically significant decrease in TM and alveolar bone height loss (ABHL), whereby the AB gain gradually increased among the groups with the best group being ABG, followed by CGF, PRF, and control groups, respectively (p=0.001). The study results support the treatment of periodontal intrabony pockets using OFD in combination with ABG, CGF, and PRF, as ABG showed the best results followed by CGF and PRF.

A-002 The Prevalence of the High Sensitivity Cardiac Troponin I Outlier and False Positivity Rates on Beckman Coulter Access DxI

Abstract Background The false positive elevation in high sensitivity cardiac troponin I (hsTnI) can be triggered by many factors, for example, fibrin clots, heterophile antibodies, or other sources of troponin interferences. These interferences lead to inaccurate hsTnI results. These inaccurate results described in the literature as the “outliers”. Published studies use statistical tools to identify the outliers based on the discrepancies between the two repeat values. Depending on the instrument platform and the study design, the outlier rate for the conventional troponin I assay was reported from 0.44% to 1.01% (1, 2). In our laboratory, the false positivity rate for the conventional troponin assay on Beckman Coulter DxI platform was determined as 1% (unpublished data). This study aim was to determine both the statistically and clinically significant outliers for hsTnI assay on the Beckman Coulter Access DxI instrument in the academic medical center clinical laboratory setting. Methods A unique test repeat protocol was created. Two parallel hsTnI measurements are conducted in lithium heparin tubes (BD Vacutainer) on Beckman Coulter DXI 800 systems. When the difference between the two results is greater than 30%, a third repeat is automatically ordered and run after additional centrifugation at a higher relative centrifugal force. The outlier determination is based on assessing the difference between the first two values using previously described statistical analysis tools (1). The clinically significant outlier was determined by counting positive results in the first two runs which are not unconfirmed by the third run, i.e., false positive results. Gender specific cutoffs, 14 ng/L for female and 19 ng/L for male, were applied to identify the positive results. Overall, 2935 patients’ results were evaluated during the study. Results Based on the analysis of the first two repeat runs, out of 2935 samples 16 samples, or 0.54%, were identified as the statistical outliers. 2 out of these 16 outliers, or 12.5%, were negative results. Taking into consideration the third repeat data, 13 out of 2935 samples, or 0.44%, were identified as false positive results. Only 9 out of 13 false positive results, or 69.2%, were identified using the statistical approach above. Conclusion The false positivity rate of hsTnI testing has dropped significantly from 1% to 0.44% in a setting of our laboratory. Our refined repeat protocol approach significantly increases the clinician’s confidences in the hsTnI results by capturing potential false positive results. This approach addresses the outliers at an additional expense like reagents, instrument wear and tear, and labor. Therefore, a more robust methodology is still desired by the industry.

Technical considerations in obtaining platelet rich fibrin for clinical and periodontal research

Autologous platelet rich fibrin (PRF), is currently being widely used and investigated across the globe by clinicians and periodontal research. The technical aspect required for the procurement of PRF includes revolution per minute (RPM), relative centrifugal force (RCF) or G-force, rotor radius, rotor angle, stability or vibration in the centrifugal machine and material of test-tube, besides the systemic health of the individual may influence the final outcome. Present technical note intends to compile these aspects for better understanding and appropriate outcome while preparing PRF in varying clinical scenarios.

Centrifugation forced ice-concentrate separation to enhance suspension freezing desalination performance

Suspension freeze desalination is a promising route for treatment of high salinity wastewater, but the poor ice-concentrate separation often generates decrease of desalination efficiency. In this work, it is demonstrated that centrifugation forced dewatering can assist in ice purification and enhance suspension freeze desalination performance. The positive correlation and good linear fitting relationship between ice purity and dewatering rate were identified at various centrifugation speeds, centrifugation time, and ice layer thickness. Changes of ice shape were recorded by low-temperature optical microscope observation system. The free water removal and ice floc destruction induced by centrifugal field have an important contribution to ice purification. Increasing centrifugation speed from 100 r/min to 500 r/min, the corresponding relative centrifugal force increased 27-fold, creating sharp increases in ice purity (rate constant k = 0.1605) and dewatering rate (rate constant D = 0.0563). Due to the strong binding characteristics and small portion of bound water, ice desalination efficiency per unit centrifugal force dropped when centrifugation speed increased from 1000 r/min to 3000 r/min. Besides, the multi-step dewatering and purification mechanism involved in ice centrifugation was depicted. The suspension freeze technology hybrid with centrifugation not only enhances desalination efficiency but also is beneficial to obtain high-purity ice.

Standardization of Animal Models and Techniques for Platelet-Rich Fibrin Production: A Narrative Review and Guideline.

Experimental research is critical for advancing medical knowledge and enhancing patient outcomes, including in vitro and in vivo preclinical assessments. Platelet-rich fibrin (PRF) is a blood by-product that has garnered attention in the medical and dental fields due to its potential for tissue regeneration and wound healing. Animal models, such as rabbits and rats, have been used to produce PRF and examine its properties and applications. PRF has demonstrated potential in the dental and medical fields for reducing inflammation, promoting tissue repair, and accelerating wound healing. This narrative review aims to compare existing evidence and provide guidelines for PRF animal research, emphasizing the importance of standardizing animal models, following ethical considerations, and maintaining transparency and accountability. The authors highlight the necessity to use the correct relative centrifugal force (RCF), standardize centrifugal calibration, and report detailed information about blood collection and centrifuge parameters for reproducible results. Standardizing animal models and techniques is crucial for narrowing the gap between laboratory research and clinical applications, ultimately enhancing the translation of findings from bench to bedside.

An ultralow-cost portable centrifuge from discarded materials for medical applications

Reliable centrifugation for medical applications has historically required access to expensive, bulky, and electricity-dependent commercial devices, which are generally unavailable in resource-poor settings. Although several portable, low-cost, non-electric centrifuges have been described, these solutions have predominately been designed for diagnostic applications requiring sedimentation of relatively small volumes. Moreover, construction of these devices frequently requires access to specialized materials and tools that are often unavailable in underserved areas. Herein, we describe the design, assembly, and experimental validation of the CentREUSE—an ultralow-cost, portable, discarded material-based, human-powered centrifuge for use in therapeutic applications. The CentREUSE demonstrated a mean centrifugal force of 10.5 relative centrifugal force (RCF) ± 1.3. Sedimentation of 1.0 mL triamcinolone acetonide suspension for intravitreal use after 3 min of CentREUSE centrifugation was comparable to that achieved after 12 h of gravity-mediated sedimentation (0.41 mL ± 0.04 vs. 0.38 mL ± 0.03, p = 0.14). Sediment compactness after 5 min and 10 min of CentREUSE centrifugation was similar to that observed after centrifugation with a commercial device for 5 min at 10 RCF (0.31 mL ± 0.02 vs. 0.32 mL ± 0.03, p = 0.20) and 50 RCF (0.20 mL ± 0.02 vs. 0.19 mL ± 0.01, p = 0.15), respectively. Templates and instructions for construction of the CentREUSE are included as part of this open-source publication.

Reproducible Quantification of Unbound Fractions of Four Beta-Lactam Antibiotics: Ultrafiltration Versus Microdialysis of Spiked Healthy Donor Plasma.

Ultrafiltration (UF) is a conventional method for isolating the protein-unbound plasma fractions of therapeutic drugs. However, the ideal UF conditions for specific compounds remain largely unexplored. By comparing UF-derived unbound concentrations with the corresponding results obtained using a reference method, the authors sought to identify appropriate UF conditions for cefotaxime, cloxacillin, flucloxacillin, and piperacillin. In vitro microdialysis (MD) with a no-net-flux approach was used as a reference method for plasma protein separation, for which UF performance was assessed. Four levels of relative centrifugal force (2500-11,290 g ) and 2 levels of temperature (37 vs. 22°C) during 10 minutes of UF centrifugation were evaluated. Ultrafiltrates and reference microdialysates were analyzed using liquid chromatography-tandem mass spectrometry to obtain unbound concentrations. After identifying the appropriate UF conditions in the spiked plasma samples, exploratory analyses of clinical samples (n = 10 per analyte) were performed. Of the evaluated UF alternatives, the best overall agreement with the MD-derived reference concentrations was obtained with 11,290 g UF performed at 22°C. For cloxacillin specifically, 37°C UF yielded better agreement than 22°C UF at 11,290 g. Clinical sample analyses indicated minimal differences between 22°C and 37°C at 11,290 g UF for cefotaxime and piperacillin. However, consistently lower levels of unbound cloxacillin (median: -23%, IQR: -19% to -24%) and flucloxacillin (median: -27%, IQR: -21 to -34%) were observed after UF at 22°C versus 37°C. For the evaluated UF device, 10 minutes of 11,290 g UF at 22°C is appropriate for flucloxacillin, cefotaxime, and piperacillin, and can arguably be justified for cloxacillin as well for laboratory practice purposes. Maintenance of 37°C during high-centrifugal UF may lead to overestimation, particularly for unbound flucloxacillin.

Effect of relative centrifugal force on the biological properties of liquid platelet-rich fibrin produced via horizontal centrifugation.

Platelet-rich fibrin (PRF) in liquid form has shown advantages in tissue engineering including acting as injectable fillers and drug carriers. However, few studies have investigated the best relative centrifugal force (RCF) for preparing liquid PRF. The aim of the present study was to find out optimal centrifugation force for preparing liquid PRF. Liquid PRF was prepared using horizontal centrifugation (liquid H-PRF) with RCF ranging from 100g, 300g, 500g, to 700g for 8min. The volume, weight, solidification time, and tensile properties were subsequently investigated. Scanning electron microscopy (SEM) and rheologic tests were carried out to investigate the microstructure and rheologic properties of liquid H-PRF after natural polymerization. The total number, concentration, and distribution of cells within each liquid H-PRF was evaluated by complete blood count (CBC) analysis and hematoxylin-eosin staining. As RCF values increased, the volume and weight of liquid H-PRF both increased accordingly. SEM images revealed that as the centrifugal force increased, the fibrin bundles became thinner with a denser fibrin network, and rheologic tests revealed improved mechanical properties. CBC analysis demonstrated that 500g group had the highest number of leukocytes and neutrophils, whereas 100g group yielded the highest concentration of leukocytes and platelets. Furthermore, histological analysis suggests that cells obtained by 500g for 8min were most evenly distributed in liquid H-PRF. In summary, the present study provided insights into the contents of liquid H-PRF prepared at different centrifugation forces, enabling clinicians to choose proper centrifugation forces based on their needs. The present findings provide theoretical basis for clinical choice of liquid H-PRF protocol from mechanical, cell contents, and histological aspects.

Third-Generation Platelet Concentrates in Periodontal Regeneration: Gaining Ground in the Field of Regeneration.

Platelets are important for hemostasis and the healing of wounds. In clinical settings, healing cytokines including insulin-like growth factors (IGF), platelet-derived growth factors (PDGF), and transforming growth factors (TGF) are commonly implemented. The regenerative approach in dentistry frequently employs platelet concentrates (PCs) that are “autologous in origin” and have a high concentration of platelets, growth factors, and leukocytes. First-generation PCs is made of platelet-rich plasma (PRP), while second-generation PC is made of platelet-rich fibrin (PRF). Both have limitations, so modification protocols and development in PRP and PRF derivatives are required for advancement mechanisms, strength, biodegradability, retention ability in the field of regenerative dentistry, and so on. As third-generation PC, newer genera kinds of PRF, such as advanced-PRF (A-PRF), advanced-PRF+ (A-PRF+), injectable-PRF (i-PRF), and titanium-PRF (T-PRF), were introduced. A-PRF matrices in their solid form were introduced using the low-speed centrifugation concept (LSCC). The applied relative centrifugal force (RCF) for A-PRF is reduced to 208 g as a result of this improved preparation process. A-PRF features a greater number of neutrophil granules in the distal region, especially at the red blood cells-buffer coat (RBC-BC) interface, and the A-PRF clot has a more porosity-like structure with a bigger interfibrous space than PRF. Since the PRF is in a gel form and is difficult to inject, i-PRF was formulated to address this problem. Compared to the other two protocols, the i-PRF protocol requires far less time, and this is the advantage of this PC. This is because i-PRF just needs the blood components to be separated, which happens within the first two to four minutes. Compared to normal L-PRF, T-PRF creates fibrin that is thicker and more densely woven. Titanium has a higher hemocompatibility than glass, which could lead to greater polymerized fibrin formation. In periodontal regenerative operations, oral surgery, and implant dentistry, PRF and its newer advanced modifications have demonstrated promising results and desirable results in both soft and hard tissue regenerative techniques.

Functional evaluation of muscle-tendon repair in athletes treated with monomeric phase platelet-rich fibrin

The autologous platelet-rich fibrin in the monomeric phase (MP-PRF) is a matricellular product obtained from the selective separation of elements in the blood by centrifugation with very low relative centrifugal force, and it appears as a possible alternative in the treatment of muscle-tendon injuries caused by therapeutically functional molecules concentrate. The objective of this study was to verify the obtained concentration of leukocytes and platelets in the matrix according to the proposed centrifugation method (fibrin protocol) and to correlate it with the functional clinical condition in patients submitted to the application of this matrix. In the laboratory phase, according to the acquisition protocol, hemocytometry was performed with anticoagulated blood samples from 05 patients recruited from the sample universe of 14 participants, where the platelet concentration of 119.35% was higher than that observed in whole blood. For the clinical experimental phase, MP-PRF obtained from non-anticoagulated blood samples, were applied to pre-existing muscle-tendon injuries with more than 30 days of evolution in the 14 participants. For functional assessment, the validated DASH and LEFS were used. Of the 14 patients selected, 13 were athletes and showed significant functional improvement three weeks after the intervention. No complications resulted from the response. The infiltrations improved the functional clinical status of the patients. There were no cases of complications, revealing that the procedure is safe. New prospective clinical studies are needed to strengthen this new therapeutic modality.

The G-Force Conundrum in Platelet-Rich Fibrin Generation

Aim:A force of 400 g at 2700 revolutions per minute (RPM) results in an optimum leukocyte and platelet-rich fibrin (L-PRF). Most of centrifuges with varying characteristics generate a g-force in excess of 700 g at 2700 RPM. In this context, the study explores the effect of the original centrifugation protocol and a modified protocol tailor-made to lower the RPM to generate a g-force of ~ 400 g on platelet concentration, clot size and growth factors release in L-PRF prepared in two different commercially available centrifuges.Materials and Methods:Twenty five subjects each were assigned to the following groups; R1 and R2 where L-PRF was obtained from two laboratory swing-out centrifuges (Remi 8C® and Remi C854®, Mumbai, India), respectively. PRF was obtained from each subject within a group using two protocols; Original (O) protocol: conforming to the original centrifugation cycle (2700 RPM for 12 min) and Modified (M) protocol. Clot size, growth factor estimation, and platelet counts were measured at 20, 40, and 60 min from all the L-PRF clots, respectively.Results:At the third time period (40–60 min), there were no significant differences in clot sizes with the original protocol (P = 0.09), but a highly significant difference was noticed with the modified protocol in both the centrifuges (P = 0.001). Our results showed an increased concentration of vascular endothelial growth factor and epidermal growth factor with modified protocol than with original protocol with both the centrifuges (P = 0.001). By the end of second and third time periods, more platelet concentration was observed with modified protocol than with the original protocol in both the centrifuges (P = 0.001).Conclusion:This study infers that the centrifuge type and relative centrifugal force can affect the quality and quantity of cells and growth factors and an optimum relationship between g-force and RPM should be maintained to obtain L-PRF with adequate cell viability and optimum growth factor release.

Fibrinogen Concentrations in Liquid PRF Using Various Centrifugation Protocols.

Liquid platelet-rich fibrin (PRF) is produced by fractionation of blood without additives that initiate coagulation. Even though liquid PRF is frequently utilized as a natural source of fibrinogen to prepare sticky bone, the concentration of fibrinogen and the overall amount of “clottable PRF” components have not been evaluated. To this aim, we prepared liquid PRF at 300, 700, and 2000 relative centrifugal force (RCF), for 8 min and quantified the fibrinogen levels by immunoassay. We report here that, independent of the RCF, the fibrinogen concentration is higher in the platelet-poor plasma (PPP) compared to the buffy coat (BC) fraction of liquid PRF and further decreases in the remaining red fraction. We then determined the weight of the clotted PRF fractions before and after removing the serum. The PPP and BC fractions consist of 10.2% and 25.3% clottable matrix suggesting that more than half of the weight of clottable BC is caused by cellular components. Our data provide insights into the distribution of fibrinogen in the different fractions of liquid PRF. These findings suggest that PPP is the main source of clottable fibrinogen, while the BC is more a cell source when it comes to the preparation of sticky bone.

A Standardized g-Force Allows the Preparation of Similar Platelet-Rich Fibrin Qualities Regardless of Rotor Angle.

Platelet-rich fibrin (PRF) is an autologous blood concentrate that supports tissue regeneration. The effect of the centrifuge rotor angle in the fabrication of PRF is still not fully elucidated. The hypothesis of this study is: When applying the same g-force (relative centrifugal force [RCF]) and centrifugation time, PRF components and bioactivity are not modified using either a swing-out rotor or a fixed angle rotor. For this purpose, peripheral blood samples (from five donors) were used to gain solid (710 ×g, 8 min) and liquid (44 ×g, 8 min) PRF matrices using three different centrifuges (one fixed angle as a control and two different swing-out rotor centrifuges). The physical characteristics of the solid PRF were measured to evaluate the clot formation and cellular distribution. The liquid PRF was used to evaluate the cell number, bioactivity, and influence on primary human osteoblasts (pOBs) and primary human fibroblasts (pHFs) in vitro. Solid PRF clots were significantly larger in the group of fixed rotor centrifuges compared with either of the two evaluated swing-out rotor centrifuges. No differences were observed when evaluating the cellular distribution within the solid PRF. No statistically significant differences were documented in the cell's density in liquid PRF samples (platelets, lymphocytes, neutrophils, eosinophils, and basophils) among the differently gained PRF samples. No statistically significant differences were documented for the released growth factors (vascular endothelial growth factor, epidermal growth factor, and transforming growth factor beta 1) over 7 days. pOBs and pHFs viability after treatment with PRF conditioned media showed no statistically significant differences between the evaluated groups. However, the number of adherent cells treated with PRF obtained with the use of the fixed angle rotor was significantly higher when compared with those treated with PRF obtained by using the swing-out rotors. The presented results confirm that regardless of the centrifuge rotor used, the components and bioactivity of solid and liquid PRF matrices are modified by the applied RCF and centrifugation time. These findings are of great importance for highlighting the essential role of adapting the centrifugation protocols when using different centrifuges and to correctly report the used centrifugation protocols in scientific research to allow for reproducible results. Impact statement Platelet-rich fibrin (PRF) is prepared from autologous peripheral blood and is widely applied in research and clinical treatments. The centrifugation parameters used during the preparation of PRF directly influence its components and bioactivity. By using a standardized protocol, the present study demonstrated that adapting various centrifuges to a standardized relative centrifugal force and centrifugation protocol resulted in reproducible PRF matrices with similar bioactivity, regardless of the centrifuge rotor angle. These findings underline the necessity to carefully adapt and correctly report the used centrifuge and centrifugation protocols in scientific research to allow reproducible results.

Effects of relative centrifugation force on L-PRF: An in vivo submandibular boney defect regeneration study.

Properties and composition of leukocyte- and platelet-rich fibrin (L-PRF) clots may be largely affected by centrifugation protocols (function of relative centrifugal force [RCF]), which may impact biological potential repair in bone regeneration. The present in vivo study sought to assess the effect of the RCF on the composition of L-PRF clots, as well as to compare the repair potential of L-PRF clots obtained with different RCF protocols in submandibular boney defects using PLGA scaffolds for bone regeneration. Complete blood count and volumetric evaluations were performed on L-PRF clots obtained through centrifugation for 12 min at 200, 400, and 600 RCF-clot centrifugation speeds. These evaluations were completed from blood collected immediately prior to any surgical procedures. The in vivo portion comprised of three submandibular unilateral, full thickness, osteotomies (~0.40cm3 ) which were created in the submandibular region of six sheep, using rotary instrumentation under continuous irrigation. Subsequently, poly(lactic-co-glycolic acid) (PLGA) scaffolds were enveloped in a L-PRF membrane from one of the three spinning speeds (n=6/RCF) and inserted into the defect (sites were interpolated to avoid site bias). Six-weeks after surgery, the mandibles were harvested en bloc and prepared for volumetric and histomorphometric evaluations. Membranes harvested from 600 RCF produced significantly larger L-PRF clots (6.97g ± 0.95) in comparison to the lower 200 RCF (5.7g ± 0.95), with no significant differences between 600 and 400, and from 400 and 200 RCF. The three tested RCFs did not alter the platelet count of the L-PRF clot. For the in vivo component, quantitative bone regeneration analyses demonstrated significantly higher values obtained with L-PRF membranes extracted post 600 RCF (27.01 ± 8%) versus 200 RCF (17.54 ± 8%), with no significant differences regarding 400 RCF (~23 ± 8%). At the qualitative histological analyses, L-PRF membranes obtained at 600 and 400 RCFs yielded improved healing throughout the defect, where the L-PRF sourced from the lowest speed, 200 RCF, presented healing primarily at the margins along with the presence of connective tissue at the central aspect of the surgical defect. Higher 600 RCF yielded larger L-PRF clots/membranes, resulting in enhanced bone repair potential in association with PLGA scaffolds for the treatment of critical size bone defects.

Fundamental Study of the Dispersion of Carbon Nano-Onions

Since the discovery of the fullerene C60 in 1985 by Curl, Kroto and Smalley, carbon nanomaterials have been the focus of interdisciplinary chemical research. Multi-shell fullerenes, known as carbon nano-onions (CNOs) discovered by Ugarte in 1992, are structured by concentric shells of carbon atoms. Different methods for their synthesis have been developed and their properties have been widely studied. In addition, the chemical functionalization of CNOs has been investigated and several synthetic pathways were found to be applicable for the introduction of a variety of functional groups. The purpose of this project is to make the oxidized CNOs bear a relative centrifugal force at different time durations to analyzed how well the material disperses. This in turn, will provide a fundamental concept for the synthesis efficiency. According to preliminary results, there is a tendency on which the concentrated CNOs difference in weight gets narrow, as duration of the centrifugal force increases. Chemically modified CNOs were probed in different fields of application and have revealed to be a promising nanomaterial that attracts a growing interest among researchers and opens new avenues for investigation. Its development starts using nano-diamonds; a carbon nanomaterial of strong structure which undergoes through a temperature of approximately 1650°C inside a furnace to obtain the CNOs structure. The CNOs are then oxidize through synthesis that requires a constant temperature and stirring to attain oxygen based functional groups. Another way to obtain the oxygen based functional groups is through heating the sample at 400°C for two hours; these procedures are then analyzed to determine the efficiency of functionalization. The preliminary elemental detection of oxygen atoms was gathered by Energy-Dispersive Spectroscopy. To detect states in the CNO’s molecular system, Raman Spectroscopy was utilized to confirm the carbon structure of CNOs by the identification of the peaks D and G characteristic of this carbon material. An in-depth characterization analysis was done using X-Ray Diffraction, providing detailed information about chemical composition, and crystalline structure. The morphology and microstructure of CNOs were studied using a Transmission Electron Microscope and Scanning Electron Microscopy. Through Cyclic Voltammetry, CNO’s ink was prepared to characterize electrochemically comparing both functionalization processes. To study its catalytic properties, Oxygen Reduction Reaction (ORR) experiments was conducted utilizing Rotating Ring-Disk Electrode (RRDE). The ORR experiments were carried out by varying the rotation rates of the RRDE at 100, 400, 900, 1600 and 2500 rpm.

Elemental sulphur production from thiosulphate under haloalkaline conditions in a Thioalkalivibrio versutus amended fluidized bed bioreactor

Concentrated sulphurous and saline streams, produced for example by pulp and paper and petrochemical industries, pose challenges for both environmental and processes management. In this study, the potential of biological recovery of S0 from haloalkaline thiosulphate solution in a Thioalkalivibrio versutus amended continuous-flow fluidized bed bioreactor (FBBR) was investigated using different (12−5 h) hydraulic retention times (HRT) as well as physico-chemical means to separate the S0 produced. S2O32− was biotransformed to SO42− and S0 with the highest biotransformation efficiency of 99.9 %. At 7 h HRT, the capacity of the FBBR was reached, seen as incomplete thiosulphate conversion. S0 production rate increased up to 6.3 ± 0.6 g S/l/d at HRT 7 h, whilst the average S0 yield was 27 ± 2 %. The presence of biologically produced S0 was visual and identified by scanning electron microscopy. Separation of S0 from the effluent by centrifugation at 3417 relative centrifugal force (rcf) resulted in 93 % separation, while among the four tested coagulants, FeCl2 at 0.5 g/l resulted in 40 % separation. Also, FeCl2 enhanced thiosulphate biotransformation rates. In summary, continuous biological S0 production followed by separation by centrifugation indicates potential for sulphur recovery from alkaline and saline industrial streams.