Speed Centrifugation Research Articles

Concentration of Microparticles/Cells Based on an Ultra-Fast Centrifuge Virtual Tunnel Driven by a Novel Lamb Wave Resonator Array.

The µTAS/LOC, a highly integrated microsystem, consolidates multiple bioanalytical functions within a single chip, enhancing efficiency and precision in bioanalysis and biomedical operations. Microfluidic centrifugation, a key component of LOC devices, enables rapid capture and enrichment of tiny objects in samples, improving sensitivity and accuracy of detection and diagnosis. However, microfluidic systems face challenges due to viscosity dominance and difficulty in vortex formation. Acoustic-based centrifugation, particularly those using surface acoustic waves (SAWs), have shown promise in applications such as particle concentration, separation, and droplet mixing. However, challenges include accurate droplet placement, energy loss from off-axis positioning, and limited energy transfer from low-frequency SAW resonators, restricting centrifugal speed and sample volume. In this work, we introduce a novel ring array composed of eight Lamb wave resonators (LWRs), forming an Ultra-Fast Centrifuge Tunnel (UFCT) in a microfluidic system. The UFCT eliminates secondary vortices, concentrating energy in the main vortex and maximizing acoustic-to-streaming energy conversion. It enables ultra-fast centrifugation with a larger liquid capacity (50 μL), reduced power usage (50 mW) that is one order of magnitude smaller than existing devices, and greater linear speed (62 mm/s), surpassing the limitations of prior methods. We demonstrate successful high-fold enrichment of 2 μm and 10 μm particles and explore the UFCT's potential in tissue engineering by encapsulating cells in a hydrogel-based micro-organ with a ring structure, which is of great significance for building more complex manipulation platforms for particles and cells in a bio-compatible and contactless manner.

Characteristics of PB 260 clone rubber coagulated with natural coagulants: type of Averrhoa

The aim of this research was to determine the properties of the PB 260 clone rubber using the Averrhoa type coagulant. The natural coagulants used in this study were Averrhoa bilimbi and Averrhoa carambola. The latex used was 150 ml of PB 260 clone rubber with a concentration of 100% natural coagulant of 75 ml and 2% formic acid. The rubber properties that were tested were Po, PRI, DRC, ash content, dirt content, volatile matter content and Mooney viscosity. This research also uses a special treatment in the form of centrifugation speed. The higher the centrifugation speed, the higher the pH value of the natural coagulant and the lower the H+ ion value, which accelerates the coagulation time of the latex. In natural coagulant extract, the highest values of Po, PRI, DRC, ash content, dirt content and Mooney viscosity were obtained at 0 rpm for Averrhoa bilimbi extract with values of 40%, 94.17%, 32.83%, 0, 32%, 0.038% and 77 MU. Meanwhile, in the test for volatile matter content, the highest value was found in Averrhoa carambola at 5000 rpm with a value of 0.23%.

Platelet-rich fibrin: A review of its role as a new treatment in androgenetic alopecia.

Androgenetic alopecia (AGA) is a major cause of hair loss resulting from a complex interplay between various genes and hormones with the result being follicular miniaturization and altered hair cycle dynamics. Platelet-rich plasma (PRP) has a well-established role as adjunctive therapy in AGA but there are many limitations of it. In an attempt to overcome the shortcomings of PRP, liquid platelet-rich fibrin (PRF) was developed. This article critically reviews the protocol for the preparation and clinical outcomes of PRF. The articles published so far in the English language regarding the preparation and clinical outcomes of PRF were reviewed. Among five studies analyzing various centrifugation speeds and centrifugation times, three of the studies favored low-speed centrifugation, whereas two studies did not support this methodology. A horizontal centrifuge may be preferred over a fixed-angle centrifuge for PRF. Five clinical studies on the use of PRF showed a significant effect on AGA. At present, there is no consensus regarding the preparation of PRF. Most studies used fixed-angle centrifugation favored low centrifuge speed and less centrifugation time. Larger studies are needed to determine the optimal centrifugation force and time. A horizontal centrifuge may be preferred over a fixed-angle centrifuge due to the higher yield of platelets, and lesser shear trauma to the cells. In addition, larger, well-designed studies are needed to confirm the benefits of PRF over PRP.

Determination of indoxyl sulfate by spectrofluorimetric method in human plasma through extraction with deep eutectic solvent

A rapid and efficient analytical method was established to quantify indoxyl sulfate (IS) in plasma through extraction technique with a deep eutectic solvent (DES) and spectrofluorimetric method. DES (choline chloride: urea) was mixed with plasma samples for the extraction of IS, followed by the addition of dipotassium hydrogen phosphate (K2HPO4) solution to form an aqueous two-phase system. The fluorescence intensity of IS which was first extracted to the DES-rich-phase and then back-extracted into the salt-rich-phase, was measured by spectrofluorimetric method. Some key factors such as pH, centrifugation speed and time, the volume ratio of DES/salt, and salt concentration were optimized. Under the optimized conditions, the suggested method had a dynamic range between 20 and 160 µg/mL with a coefficient of determination (R2) of 0.99. Precision (relative standard deviation) was less than 15% and accuracy (% relative recovery) was ± 15% at the nominal concentration level. In addition, results showed that IS levels in real samples were higher than 40 µg/mL which was compatible with reported IS levels in end-stage renal disease (ESRD) patients. Overall, all the results reflect the fact that the presented analytical method can potentially be used for the determination of IS in real plasma samples.

Fully integrated and automated centrifugal microfluidic chip for point-of-care multiplexed molecular diagnostics

Public health events caused by pathogens have imposed significant economic and societal burdens. However, conventional methods still face challenges including complex operations, the need for trained operators, and sophisticated instruments. Here, we proposed a fully integrated and automated centrifugal microfluidic chip, also termed IACMC, for point-of-care multiplexed molecular diagnostics by harnessing the advantages of active and passive valves. The IACMC incorporates multiple essential components including a pneumatic balance module for sequential release of multiple reagents, a pneumatic centrifugation-assisted module for on-demand solution release, an on-chip silicon membrane module for nucleic acid extraction, a Coriolis force-mediated fluid switching module, and an amplification module. Numerical simulation and visual validation were employed to iterate and optimize the chip's structure. Upon sample loading, the chip automatically executes the entire process of bacterial sample lysis, nucleic acid capture, elution quantification, and isothermal LAMP amplification. By optimizing crucial parameters including centrifugation speed, direction of rotation, and silicone membrane thickness, the chip achieves exceptional sensitivity (twenty-five Salmonella or forty Escherichia coli) and specificity in detecting Escherichia coli and Salmonella within 40 min. The development of IACMC will drive advancements in centrifugal microfluidics for point-of-care testing and holds potential for broader applications in precision medicine including high-throughput biochemical analysis immune diagnostics, and drug susceptibility testing.

Determination of Fe, Cu, and Pb in edible oils using choline chloride:ethylene glycol deep eutectic solvent-based dispersive liquid-liquid microextraction associated with microwave-induced plasma optical emission spectrometry

A new simple, fast and environmentally friendly deep eutectic solvent based dispersive liquid-liquid microextraction (DES-based DLLME) methodology assisted by vortex is presented for the separation and preconcentration of three elements (i.e., Fe, Cu and Pb) from edible oil samples (i.e., soybean, sunflower, rapeseed, sesame, and olive oil) prior to the determination by microwave-induced plasma optical emission spectrometry (MIP-OES). The deep eutectic solvent selected as extractant (i.e., choline chloride and ethylene glycol, 1:2) is synthesized and characterized by Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance spectroscopy (1H NMR) and differential scanning calorimetry (DSC), and the extraction conditions are optimized by a two steps experimental design. Under the optimum extraction conditions (i.e., diluted sample weight: 8.6 g; DES volume: 100 μL; extraction time: 1 min; centrifugation time and speed: 3 min and 3000 rpm; and dispersion system: vortex) the analytical method presents excellent linearity (i.e., R2 values higher than 0.99) in the range 10–500 μg kg−1, repeatability (i.e., CV values lower than 9.2%), and limits of detection (LOD) values of 3, 2 and 0.7 μg kg−1 for Pb, Fe and Cu, respectively. None of the analytes displayed amounts over the upper limit permitted by law, and recovery values of all analytes evaluated in the different samples using external standard calibration were close to 100%, which excludes significant matrix effects. Finally, AGREEprep metric has been used to evaluate the method greenness (final score of 0.47) and it has been compared successfully with previous publications for the same type of analytes and matrices.

The influence of imbalances on the dynamic characteristics of the laboratory centrifuge HERMLE Z306

Laboratory centrifuges are used in various industries. During operation, vibrations occur that lead to resonant frequencies, which in turn impair functionality. This paper presents an overview of the computational model of the HERMLE Z306 laboratory centrifuge used in medical laboratories to separate mixtures of different fractions to determine the dynamic characteristics. The zones of stable operation of the centrifuge and the influence of the rotation speed on the natural frequencies are analytically determined. Experimental results are presented with the influence of imbalances on the dynamic characteristics of the HERMLE Z306 centrifuge. As a result of the modeling, the amplitude-frequency characteristics are determined and a Campbell diagram is constructed. Objective: Modeling of dynamic processes in laboratory centrifuges by studying the influence of imbalances on the quality of mixture separation. Determination of zones of stable operation of the centrifuge.Purpose: Construction of amplitude-frequency characteristics of the centrifuge, determination of zones of stable operation of the laboratory centrifuge during separation and Campbell diagram showing the dependence of natural frequencies on the rotation speed of the HERMLE Z306 centrifuge. This diagram makes it possible to determine the resonance zones. Methods of implementation: Based on the use of the Lagrange equation of the second kind, a model is obtained that makes it possible to determine the zones of stable operation of the centrifuge. Using experimental equipment, determine the frequency response of the centrifuge and analyze the Campbell diagram to determine the resonance zones.Results: The zones of stable operation of a laboratory centrifuge were analytically determined. The amplitude-frequency characteristics of the HERMLE Z306 centrifuge were constructed, the trajectories of the free end of the shaft were built taking into account the corresponding imbalances, and the resonance zones were experimentally determined. Conclusions: Experimental studies have shown that the free end of a laboratory centrifuge shaft moves along a surface whose shape and, accordingly, the path of movement depend on both the angles of rotation and translational movement that arise as a result of deformations of elastic supports. The analytical and experimental studies made it possible to identify unstable modes and thereby determine the areas of the centrifuge's operating modes. The separation process will be stable if the roots of the equation have a negative real part, and moreover, the motion will be asymptotically stable in the presence of resistance forces. An experimental technique for determining the dynamic parameters of the centrifuge has been developed. On its basis, the effect of the rotation speed on the natural frequencies was determined.

Recent overview of microextraction of metal ions and pharmaceuticals by solidified floating organic drop microextraction techniques

AbstractThis work presents a comprehensive overview of solidified floating organic drop microextraction, with a particular emphasis on its applications in the analysis of heavy metal ions and different pharmaceutical compounds by sample pretreatment, complexation, and their identification by various analytical techniques. Here, we discussed basic principles, procedures, applications of the technique, and effects of different variables like pH, temperature, stirring rate, extraction time, salts addition, extraction solvent and extraction volume, centrifugation speed, and, vortex time on preconcentration. In brief, the review summarises the various modes of solidified floating organic drop microextraction such as dispersive liquid‐liquid microextraction, ultrasound‐assisted, air‐assisted liquid‐liquid microextraction, and vortex‐assisted solidified floating organic drop microextraction. this review covers the methods combined with analytical techniques such as inductively coupled plasma‐optical emission spectrometry, electrothermal atomic absorption spectrometry, flame atomic absorption spectroscopy, graphite furnace atomic absorption spectrometry, electrothermal vaporization inductively coupled plasma mass spectrometry, high‐performance liquid chromatography, and gas chromatography/mass spectrometry. among these, the incorporation of ultrasonic, vortex, and air agitation improves the dispersion mechanism. The coupling of solidified floating organic drop microextraction with other techniques enhances the selectivity and efficiency of the preconcentration procedure. This review provides a potential overview of the fundamental principles, advancements in various modes, influencing factors, and applications of solidified floating organic drop microextraction, showing its potential for advancements in sample preparation and analytical methodologies across various domains.

Response Surface Methodology for Optimization of Mucilage Extraction from Dioscorea alata Tuber

Dioscorea alata mucilage (DAM) is a water-soluble polysaccharide and is composed of glucomannan. In this research, mucilages from D. alata were extracted using Response surface methodology (RSM) with a Central Composite Design (CCD) followed by distance-based optimality design, with three independent variables applied, i.e., temperature (4 – 60°C), time (0 – 30 h), and centrifugal speed (1.386 – 22.615×g). The maximum DAM yield was 5.89% ± 0.50%, which was obtained with an extraction temperature of 36.2°C for 13.3 h extraction time and centrifugation at 12,322×g. The regression model from RSM – CCD predicted that the maximum DAM yield was 5.47%, with R2 of 99.59% and adjusted R2 of 97.72%, which shows a significant correlation between the experimental and predicted values. The DAM is a complex material that mainly contains polysaccharides, i.e., β-pyranose forms of glucose and mannose, with low protein content. Water and oil holding capacity of the DAM powder were 8.43 g/g and 5.08 g/g, respectively, which considered as the highest compared to other similar studies. Keywords: Dioscorea alata mucilage, Extraction, Optimization, Response surface methodology, Physicochemical properties

Research on Vibration Reduction in the Transmission System of Plastic Centrifugal Pump

The inherent weakness in the deformation resistance of plastic centrifugal pumps makes them prone to vibrations. This study explores the impact of flow components on the vibrations of such pumps. Utilizing the given parameters, the primary structural parameters of the plastic centrifugal pump were calculated. The study focused on the torsional vibrations within the pump shaft transmission system, employing a silicone oil damper for vibration mitigation. A dual-mass forced torsion vibration model was developed for the pump shaft transmission system with the added damper. The optimal damping coefficient for this damper was determined, and its structural design was completed, including the creation of three-dimensional models and two-dimensional part drawings. Utilizing a ZT-3 type rotor test bench, a mathematical model correlating centrifugal pump speed with deflection was developed, and the effectiveness of various polynomials was assessed. The analysis showed that the optimal damping value for the silicone oil damper is 0.22. Compared to the system without the damper, the vibration frequency reduced by 10.45%, and the vibration amplitude decreased by 49.29%, demonstrating excellent vibration reduction effectiveness.

Study of centrifuge conditions for preparing rabbit leukocyte-poor platelet-rich plasma by single centrifugation

To explore the best centrifuge condition for preparing rabbit leukocyte-poor platelet-rich plasma (LP-PRP) by using single centrifugation method. Sixteen healthy New Zealand rabbits, aged 3-4 months, were utilized in the investigation. A total of 15 mL anticoagulated blood was extracted from the central ear artery of each rabbit, with a repeat of the blood collection procedure after 1 and 2 months. The obtained blood specimens were individually subjected to centrifugation at a radius of 16.7 cm and speeds of 1 200, 1 300, 1 400, and 1 500 r/min (equivalent to centrifugal forces of 269× g, 315× g, 365× g, and 420× g) for durations of 2, 3, 4, and 5 minutes, resulting in a total of 16 groups. Following centrifugation, collect plasma from each group to a distance of 1.5 mL from the separation plane. The volumes, platelet enrichment coefficient, and platelet recovery rates of LP-PRP in each group, under varying centrifugation conditions, were methodically computed and subsequently compared. The volume of LP-PRP obtained under all centrifugation conditions ranged from 1.8 to 7.6 mL. At a consistent centrifugal speed, an extension of centrifugation time leaded to a significant increase in the volume of LP-PRP, accompanied by a declining trend in the platelet enrichment coefficient of LP-PRP. When centrifuged for 2 minutes, the volume of LP-PRP at speeds of 1 200 and 1 300 r/min was less than 2.0 mL, while the volume of LP-PRP obtained under other conditions was more than 2.0 mL. When centrifuged for 4 and 5 minutes, the volume of LP-PRP obtained at each speed was more than 4 mL. LP-PRP with a platelet enrichment coefficient more than 2.0 could be prepared by centrifuging at 1 200 r/min for each time group and 1 300 r/min for 2 and 3 minutes, and the highest LP-PRP platelet enrichment coefficient could be obtained by centrifugation for 2 minutes at a speed of 1 200 r/min. The platelet recovery rates of LP-PRP obtained by centrifugation at 1 200 r/min for 4 and 5 minutes, as well as centrifugation at 1 400 r/min for 5 minutes, were both greater than 60%. There was no significant difference between the groups when centrifuged at 1 200 r/min for 4 and 5 minutes ( P>0.05). In the process of preparing rabbit LP-PRP using a single centrifugation method, collecting 15 mL of blood and centrifuging at a radius of 16.7 cm and speed of 1 200 r/min for 4 minutes can prepare LP-PRP with a volume exceeding 2.0 mL, platelet enrichment coefficient exceeding 2.0, and platelet recovery rate exceeding 60%. This centrifugal condition can achieve the optimal LP-PRP action parameters in the shortest possible time.

Impacts of the Local arm on the local circular velocity inferred from the Gaia DR3 young stars in the Milky Way

ABSTRACT A simple one-dimensional axisymmetric disc model is applied to the kinematics of O type and B type stars (OB stars) near the Sun obtained from Gaia Data Release 3 catalogue. The model determines the ‘local centrifugal speed’ Vc(R0) – defined as the circular velocity in the Galactocentric rest frame, where the star would move in a near-circular orbit if the potential is axisymmetric with the local potential of the Galaxy. We find that the Vc(R0) values and their gradient vary across the selected region of stars within the solar neighbourhood. By comparing with an N-body/hydrodynamic simulation of a Milky Way-like galaxy, we find that the kinematics of the young stars in the solar neighbourhood is affected by the Local arm, which makes it difficult to measure Vc(R0). However, from the resemblance between the observational data and the simulation, we suggest that the known rotational velocity gap between the Coma Bernices and Hyades-Pleiades moving groups could be driven by the co-rotation resonance of the Local arm, which can be used to infer the azimuthally averaged circular velocity. We find that Vc(R) obtained from the D < 2 kpc sample is well matched with this gap at the position of the Local arm. Hence, we argue that our results from the D < 2 kpc sample, Vc(R0) = 234 ± 2 km s−1, are close to the azimuthally averaged circular velocity rather than the local centrifugal speed, which is influenced by the presence of the Local arm.

Characterization of magnetostrictive bi-stable rotational vibration energy harvester with integrated centrifugal effect

Rotational machinery is a common presence in dust still production, and the occurrence of operational failures in components like engines and turbine blades necessitates effective measures. To solve this challenge, remote structural health monitoring using energy harvesting and wireless sensors has been widely employed to realize self-powered sensing. This study proposes a magnet-induced bi-stable rotational energy harvester (REH), which utilizes the centrifugal effect to broaden the effective frequency bandwidth, enabling efficient energy harvesting in complex environments. A comprehensive mathematical model has been established to facilitate the dynamic characteristics of the bi-stable system, taking into account the centrifugal effect. The theoretical results demonstrate that the gap distance of magnetic configuration has great effects on the bi-stable system. Additionally, the centrifugal effect decided by the centrifugal radius and rotational speeds also affects the stable high-energy orbit oscillations. Furthermore, experimental results indicate that the proposed REH can effectively operate within the frequency range of 230–290 rpm, with a maximum RMS voltage of 780 mV and corresponding power of 4.35 mW. These findings validate the performance of the bi-stable magnetostrictive REH with the centrifugal effect and indicate its potential to effectively address the power supply challenges for wireless sensors. Overall, this study presents a promising solution for enhancing the energy harvesting performance of REH and also provides insights into the design of high-efficiency REH by magnet-induced nonlinearity and the centrifugal effect.

Maxillary sinus surgery and use of fibrin-rich plasma: a systematic review

Introduction: In around 25% of all maxillary sinuses, there is an accessory bone that is located in a lower portion than the main ostium, and all the mucus produced and the particles trapped in this mucus are directed through the ciliary beat to the ostium. When a dental element is lost in the posterior region of the maxilla, there is natural reabsorption of the alveolar process and at the same time, pneumatization of the maxillary sinus occurs. Objective: It was to carry out a systematic review to elucidate the main clinical approaches to the use of fibrin-rich plasma in the bone regeneration process in maxillary sinus surgeries. Methods: The PRISMA Platform systematic review rules were followed. The search was carried out from October to December 2023 in the Scopus, PubMed, Science Direct, Scielo, and Google Scholar databases. The quality of the studies was based on the GRADE instrument and the risk of bias was analyzed according to the Cochrane instrument. Results and Conclusion: A total of 115 articles were found, 40 articles were evaluated in full and 25 were included and developed in the present systematic review study. Considering the Cochrane tool for risk of bias, the overall assessment resulted in 20 studies with a high risk of bias and 25 studies that did not meet GRADE and AMSTAR-2. Most studies did not show homogeneity in their results, with X2=55.5%<50%. It was concluded that to improve osseointegration and bone anchorage, surface modifications can be chemical, such as calcium phosphate (Ca-P), or physical impregnation, being related to the microtopography of the implant. Several variables affect the biological activity of FRP preparations, such as the number of centrifuges used, centrifugation speed, and other protocols that result in preparations with various volumes, platelet numbers, amount of growth factors, and concentration of fundamental white blood cells and erythrocytes. Some researchers recommend avoiding tissue exposure to FRP-containing leukocytes, arguing that an inflammatory reaction may occur. On the other hand, other authors have described beneficial effects due to increased immunological and antibacterial resistance, although there is no clinical evidence to support its effect. FRP has gained prominence in the scientific community because it does not require the addition of an activator or anticoagulant, making the product more autologous, and featuring a fibrin network that protects growth factors, keeping them in place for longer.

Method for Measuring the Mass Fraction of Soybean Trypsin Inhibitor: Features of Development and Certification

Modern industrialization increases the requirements for the accuracy of identifying allergens, especially those that have a negative impact – soy trypsin inhibitor (STI). Correct determination of the presence of STI in food products containing soybeans is key for product safety control and labeling. The authors set a goal to develop and certify a method for measuring the mass fraction of STI using an enzyme-linked immunosorbent assay – a technique that may increase the specificity of the method and avoid false-negative results. The object of research was a method for analyzing food allergens – an enzyme-linked immunosorbent assay carried out with a set of reagents produced by XEMA LLC. In the process of developing the measurement method, the main methodological factors influencing the accuracy of the measurement results were optimized: sample weight, time of its extraction, time and speed of sample centrifugation, ratio of supernatant liquid to ELISA buffer, incubation temperature, interaction time of the allergen-antibody complex with the coloring agent, the wavelength for measuring absorbance, and the maximum time for measuring absorbance after introduction of the stop reagent. The developed method was tested during an interlaboratory experiment with the participation of 5 laboratories. Metrological characteristics were established in accordance with RMG 61–2010. The proposed method was certified in accordance with the requirements of GOST R8.563-2009, No. 102–FZ. The method has a wide range of quantitative determination of the mass fraction of STI from 0.5 to 25.0 μg/kg (ppb) with a detection limit of 0.1 μg/kg (ppb) and a relative error of 40 %. Based on the results of the research, the Federal Information Fund for Ensuring the Uniformity of Measurements (FIF) registered a certified method for identifying and quantifying the content of non-infectious food allergens of plant protein origin in samples of all types of food products and objects related to the requirements for food products, swabs taken from working surfaces during production control using reagent kits for an enzyme-linked immunosorbent assay produced by XEMA LLC No. FR.1.31.2022.43884. The method is intended for use in testing laboratories involved in monitoring the quality and safety of manufactured products; it can be used to confirm product compliance with the mandatory requirements established in the Technical Regulations of the Customs Union TR CU022/2012.

PLATELET-DERIVED EXTRACELLULAR VESICLES PROMOTE STEM CELL TENOGENIC COMMITMENT IN A BIOENGINEERED TENDON 3D MODEL

Worldwide, tendon disorders are one of the main causes of disability that decrease the quality of life of individuals and represent a substantial economic burden on society. Currently, the main therapies used for tendon injuries are not able to restore tendon functionality, and due to tendons' hypovascular and hypocellular nature, they present a reduced healing capacity, which also limits the success of the available therapies. In order to discover new therapies, extracellular vesicles (EVs), key players in cell-cell communication, have been widely explored for tissue engineering and regenerative medicine applications. Thus, the aim of this study is to assess the role of EVs derived from platelets in stem cell tenogenic commitment using a bioengineered tendon in vitro model for potential use as tendon therapeutic agents. Biomimetic platelet-derived EVs were produced by freeze-thaw cycles of platelets and isolation at different centrifugation speed. To recreate the architecture of tendons, a 3D system consisting of electrospun anisotropic nanofiber scaffolds coated with collagen encapsulating human adipose stem cells (hASCs) and different types of platelet-derived EVs, were produced. Then, the influence of the tendon-mimetic constructs and the distinct EVs populations in the hASCs tenogenic differentiation were assessed over culture time. We observed that the hASCs on the nanofibrous tendon scaffolds, show high cytoskeleton anisotropic organization that is characteristic of tenocytes. Moreover, acting as biological cues, platelet-derived EVs boosted hASCs tenogenic commitment, supported by the increased gene expression of tendon-related markers (SCX and TNMD). Additionally, EVs enhanced the deposition of tendon like extracellular matrix (ECM), as evidenced by the increased gene expression of ECM-related markers such as COL1, COL3, DCN, TNC, and MMP-3, which are fundamental for ECM synthesis and degradation balance. Moreover, EVs induced lower collagen matrix contraction on hASCs, which has been related with lower myofibroblast differentiation. Overall, the results revealed that EVs are capable of modulating stem cells' behavior boosting their tenogenic commitment, through the increased expression of healthy tendon cell markers, potentiating ECM deposition and decreasing cell contractility. Therefore, platelet EVs are a promising biochemical tool, worthy to be further explored, as paracrine signaling that might potentiate tendon repair and regeneration.

Ternary solvent based homogeneous liquid-liquid microextraction for the preconcentration of organochlorine pesticides from water and apple juice samples.

In the present study, the optimal experimental conditions were determined by optimizing the effect of extraction solvent types and volume, salt types and concentration, centrifugation speed and time using one variable at a time. Under optimal experimental conditions, calibration curves were constructed separately using water and apple juice samples as representative matrices, and good linearities were achieved over a wide concentration range of 0.2-1600 ng L-1 with a coefficient of determination (r2) ≥ 0.998. The limits of detection (LOD) and limits of quantification (LOQ), determined to be 3 and 10 times the signal-to-noise ratios (S/N), were between 0.07-3.9 and 0.2-12.0 ng L-1 for water samples and 2.6-10.0 and 8.0-30.0 ng L-1 for the apple juice sample respectively. The precisions study showed %RSD values of ≤6% for both matrices, indicating satisfactory precisions. The enrichment factors and recoveries of the proposed method ranged from 41.4-74.5 and 86-109% respectively. The proposed method could be used as a simple and environmentally friendly alternative for the analysis of OCPs from environmental and food matrices. This method potentially offers a more sustainable and effective approach to monitoring OCPs in environmental and food products. Its use in the analysis of apple juice samples is particularly novel and can provide valuable insights into pesticide contamination in fruit juices.

Is it necessary to calibrate the rotational speed of the centrifuge?

Centrifuge has become a commonly used device in medical and dental clinics, especially for preparing platelet-rich plasma and platelet-rich fibrin. The preparation protocol depends on the centrifugal force generated by the centrifugation process, which is directly affected by the rotational speed of the centrifuge. Therefore, any less accuracy in the real rotational speed results in a change in the centrifugal force that can affect the properties of the resulting material. For this reason, this study aims to ascertain whether the selected rotational speed of the centrifuge can be relied upon as an actual speed and can be used in the calculation of the centrifugal force. Fifteen new centrifuges from different origins were randomly selected. Each centrifuge was set at a specified speed. Then, two tubes were placed inside each one. A thin, flexible piece of plastic was placed touching the cap of the tubes during their rotation to make a sound. Following that, the sound was recorded with a special recording device. Subsequently, the fifteen recorded audio files were analyzed using a software application. Finally, the number of waves per minute was counted, and the rotational speed was calculated. It was found that ten of fifteen devices showed significant differences between the selected speed and the actual speed. Moreover, the percentage difference for these ten centrifuges ranged from 15-43%. In conclusion, it is recommended to pre-assess and calibrate the centrifugal speed in the beginning, to obtain the required centrifugal force.

Effect of Centrifugation Speed and Time on the Blood Chemistry Values of Healthy Individuals

Blood chemistry testing requires centrifugation as one of the crucial pre-analytical phases. Usual differences in the speed and time of centrifugation influence specimens to varying extents among laboratories. This prompted the researchers to ascertain the effects of varying centrifugation speeds and times on healthy individuals' blood chemistry values and reduce the centrifugation time attested by the World Health Organization (WHO). Blood specimens were collected from four healthy adults, centrifuged, and then analyzed using the VITROS 5600 Automated Machine. The dry chemistry principle was applied. Three sets of speed and time were applied (1) 3,500 RPM for 15 minutes (WHO recommended), (2) 3,750 RPM for 10 minutes, and (3) 4,000 RPM for 5 minutes. The parameters include Fasting Blood Sugar (FBS), Total Cholesterol (Total CHOLE), Creatinine (Crea), Sodium (Na), and Potassium (K). The results of the serum chemistry values have no significant difference between different speeds and times against the standard set by WHO and were found to be acceptable, normal, and close in range with each other. Therefore, these can be substituted for the WHO-recommended speed and time. The researchers forward the following recommendations: (1) tests should be conducted to respondents with comorbidities and to younger and older individuals; (2) conduct the tests in triplicates and consider using other methods and more participants should be considered; and; (3) consider lesser time in centrifugation.

EVALUATION OF PLATELET RICH PLASMA (PRP) PREPARATION PROCEDURE

The success of PRP therapy in repairing tissue damage is influenced by the PRP preparation procedure. Currently, there’s no standardization of PRP preparation procedures, and various techniques are used, such as the use of anticoagulants and different centrifugation speeds. This study aimed to evaluating the PRP preparation procedures based on the centrifugations steps (single and double centrifugation) and the use of anticoagulants variation (sodium citrate, EDTA and ACD-A). This study was an experimental study and used blood samples from respondents. The selected respondents must meet inclusion and exclusion criteria. The treatment groups in this study were the single centrifugation group and the double centrifugation group. Each group will be divided into 3 subgroups with different anticoagulant usage (sodium citrate, EDTA and ACD-A). Statistical analysis results showed a significant difference in the mean platelet count in the sodium citrate , EDTA, ACD-A groups with single and double centrifugation steps. Evaluation of platelet preparation procedures in this study, a higher platelet count was obtained, specifically in the sodium citrate group (494 x 103 cells/µL), EDTA group (829.4 x 103 cells/µL), and ACD-A group (607.1 x 103 cells/µL), compared to single centrifugation in the sodium citrate group (354.8 x 103 cells/µL), EDTA group (408.1 x 103 cells/µL), and ACD-A group (390.6 x 103 cells/µL). The highest platelet count in PRP was achieved with the preparation procedure using EDTA as the anticoagulant with double centrifugation. Further research is necessary to evaluate PRP preparation procedures regarding the concentration of growth factors present in PRP.