A Novel Mouse Model to Study Fracture Healing of Tibia

Background Delayed union of most tibial fractures due to their special anatomical structures.So an effective animal model is very important to study the mechanism and method of fracture healing.However, due to the small tibia of mice, the operation is difficult, and the surgical model requires high surgical skills. The construction of the fixation model of intramedullary nail for this fracture has improved and simplified the traditional fixation model of intramedullary nail, which not only achieves the purpose of constructing the fracture model, but also makes it more simple and effective.Therefore, the aim of the current study was to develop a new mouse model to study fracture healing of tibia. Methods We chose a combination between an open osteotomy and intramedullary stabilization. The 22G needle was inserted into the fracture end in a closed manner by using an open approach for osteotomy at the middle and lower 1/3 level of the tibia.Fractured tibia were analyzed using microcomputed tomography and histology at days 7,14,21and 28after surgery. All animals displayed normal limb loading and a physio-logical gait pattern within the first three days after fracture. No animals were lost due to surgery or anesthesia. Results X-ray confirmed that the fracture types obtained by the fracture modeling method were transverse fractures. X-ray, Micro-CT, immunohistochemistry, histological staining and Real-time PCR showed that the fracture healing of mice was typical endochondral ossification, with high repeatability. Conclusion The mouse tibial fracture model established by intramedullary nailing is safe, rapid and simple. Its fracture healing is a typical intrachondral ossification with high repeatability, which can be better used for the study of molecular mechanism and clinical transformation of fracture healing and bone metabolism.

Novel Method of Measuring Corneal Viscoelasticity Using the Corvis ST Tonometer

Background: The process of rapid propagation of the corneal deformation in air puff tonometer depends not only on intraocular pressure, but also on the biomechanical properties of the cornea and anterior eye. One of the biomechanical properties of the cornea is viscoelasticity, which is the most visible in its high-speed deformations. It seems reasonable to link the corneal viscoelasticity parameter to two moments of the highest speed of corneal deformations, when the cornea buckles. The aim of this work is to present a method of determining the time and place of occurrence of corneal buckling, examine spatial and temporal dependencies between two corneal applanations and bucklings in the Corvis ST tonometer, and correlate these dependencies with corneal viscoelastic properties. Methods: Images of the horizontal cross section of the Corvis ST deformed cornea from the air puff tonometer Corvis ST were used. 14 volunteers participated in the study, each of them had one eye measured eight times. Mutual changes in the profile slopes of the deformed corneas were numerically determined. They describe pure corneal deformation, eliminating the influence of rotation, and displacement of the entire eyeball. For each point in the central area of the corneal profile, the maximum velocities of mutual slope changes accompanying the applanations were estimated. The times of their occurrence were adopted as buckling times. Results: The propagation of buckling along the corneal profile is presented, as well as the repeatability and mutual correlations between the buckling parameters and intraocular pressure. Based on the relationship between them, a new parameter describing corneal hysteresis: Corvis Viscoelasticity (CVE) is introduced. It is characterized by high repeatability: ICC = 0.82 (0.69–0.93 CI) and low and insignificant correlation with intraocular pressure: r = 0.25 (p-value = 0.38). Conclusion: The results show for the first time how to measure the corneal buckling and viscoelastic effects with Corvis ST. CVE is a new proposed biomechanical parameter related to the viscoelastic properties of the cornea, which has high repeatability for the examined subject. The distribution of its values is planned to be tested on different groups of patients in order to investigate its clinical applicability.

Towards Repeatable, Scalable Graphene Integrated Micro-Nano Electromechanical Systems (MEMS/NEMS)

The demand for graphene-based devices is rapidly growing but there are significant challenges for developing scalable and repeatable processes for the manufacturing of graphene devices. Basic research on understanding and controlling growth mechanisms have recently enabled various mass production approaches over the past decade. However, the integration of graphene with Micro-Nano Electromechanical Systems (MEMS/NEMS) has been especially challenging due to performance sensitivities of these systems to the production process. Therefore, ability to produce graphene-based devices on a large scale with high repeatability is still a major barrier to the commercialization of graphene. In this review article, we discuss the merits of integrating graphene into Micro-Nano Electromechanical Systems, current approaches for the mass production of graphene integrated devices, and propose solutions to overcome current manufacturing limits for the scalable and repeatable production of integrated graphene-based devices.

Moiré topography as a screening and diagnostic tool—A systematic review

Diagnostic investigation can be carried out using non-radiological and non-contact methods. Moiré topography (MT) seems to be a viable alternative to radiographic research in evaluating the spine and/or trunk deviations. The aim of this systematic review was to analyze the current knowledge regarding the reliability and validity of Moiré topography as a screening and diagnostic tool. The systematic review was performed from 2010 until March 2021 in the PubMed, EBSCO, Web of Science, and Scopus databases, according to the eligibility criteria. This review fulfilled the following criteria according to the PICO system: population (children and adolescents), intervention (MT measurement), comparison (repeated MT measurements, MT compared to Cobb angle or scoliometer), outcome (reliability and validity of MT). Eight studies fulfilled the inclusion criteria for further analysis. All the studies were assessed to be of high quality. Included studies found that MT had high repeatability and high intraobserver and interobserver correlation, and correlation between MT parameters and radiographic Cobb angle ranged from moderate to high. The authors reported difficulty in defining the cut-off values for MT parameter (Surface Trunk Rotation—STR), and unsatisfactory sensitivity and specificity of MT examination. The studies did not reveal the advantage of MT as a screening method in the detection of idiopathic scoliosis in comparison to radiograph. Based on the evidence from eight studies, the results indicated moderate evidence for reliability and validity of Moiré topography as a screening and diagnostic tool. There is still no strong evidence for the accuracy of MT.

Evaluating sources of technical variability in the mechano-node-pore sensing pipeline and their effect on the reproducibility of single-cell mechanical phenotyping

Cellular mechanical properties can reveal physiologically relevant characteristics in many cell types, and several groups have developed microfluidics-based platforms to perform high-throughput single-cell mechanical testing. However, prior work has performed only limited characterization of these platforms’ technical variability and reproducibility. Here, we evaluate the repeatability performance of mechano-node-pore sensing, a single-cell mechanical phenotyping platform developed by our research group. We measured the degree to which device-to-device variability and semi-manual data processing affected this platform’s measurements of single-cell mechanical properties. We demonstrated high repeatability across the entire technology pipeline even for novice users. We then compared results from identical mechano-node-pore sensing experiments performed by researchers in two different laboratories with different analytical instruments, demonstrating that the mechanical testing results from these two locations are in agreement. Our findings quantify the expectation of technical variability in mechano-node-pore sensing even in minimally experienced hands. Most importantly, we find that the repeatability performance we measured is fully sufficient for interpreting biologically relevant single-cell mechanical measurements with high confidence.

A new multi-species Protein A-ELISA assay for plague diagnosis in humans and other mammal hosts

Background: The Hemagglutination assay (HA) is widely used in plague diagnosis, however, it has a subjective interpretation and demands high amounts of antigen and other immunobiological supplies. Conventional IgG-ELISA is limited by the need of specific conjugates for multiple plague hosts. Methods: Thus, we developed an ELISA Protein A-peroxidase method to detect anti-F1 antibodies across several species, including humans. To determine the cut-off and performance rates, HA results from 288 samples (81 rabbits, 64 humans, 66 rodents and 77 dogs) were used as reference. Results: Optimal conditions were found with 250ng/well of F1 and 1:500 serum dilution. Protein A-ELISA showed high repeatability and reproducibility. The positive/negative OD ratios were higher in Protein A-ELISA and there was no significant cross-reaction with other pathogenic yersiniae. The overall sensitivity/specificity, area under the curve and Kappa rates for Protein A-ELISA were 93.9/98.9%; 0.993 and 0.938, respectively. Similar results were observed in each species separately. There was a strong agreement between Protein A and IgG assays (kappa=0.973) in independent analysis (n=487). Conclusions: Altogether, the Protein A-ELISA showed high performance when compared both to HA and IgG-ELISA, with a polyvalent single protocol that requires reduced amounts of antigen and can be employed to any plague hosts.

Non-Destructive Method in Determining the Barley Grain Vitreousity

Possibilities of non-destructive express-evaluation of the barley grain vitreousity using machine vision and digital image processing methods were studied. The study was carried out with the proprietary design hardware and software complex on barley samples of three different varieties provided by the LLC "Nosters". Transmittance in the near IR wavelength range was used as the objective criterion in classifying grains as vitreous, partially vitreous and better use powdery. Classification group boundaries were determined empirically by the cross-section inspection method. The optimal filming mode was experimentally selected, and the algorithm for digital processing of grain images was developed in order to determine the number of better use powdery grains in a sample. In addition to classifying grains by vitreousity, the proposed approach also makes it possible to evaluate uniformity of a sample by this indicator and, thus, to identify a grain of higher quality. It was found out that grain orientation introduces an error of not more than 5 %, and high repeatability of the results and, as a consequence, accuracy of the algorithm are characterized by the variation coefficient of 1.1 %

Piezoelectric Silicon Micropump for Drug Delivery Applications

Subcutaneous injection is crucial for the treatment of many diseases. Especially for regular or continuous injections, automated dosing is beneficial. However, existing devices are large, uncomfortable, visible under clothing, or interfere with physical activity. Thus, the development of small, energy efficient and reliable patch pumps or implantable systems is necessary and research on microelectromechanical system (MEMS) based drug delivery devices has gained increasing interest. However, the requirements of medical applications are challenging and especially the dosing precision and reliability of MEMS pumps are not yet sufficiently evaluated. To enable further miniaturization, we propose a precise 5 × 5 mm2 silicon micropump. Detailed experimental evaluation of ten pumps proves a backpressure capability with air of 12.5 ± 0.8 kPa, which indicates the ability to transport bubbles. The maximal water flow rate is 74 ± 6 µL/min and the pumps’ average blocking pressure is 51 kPa. The evaluation of the dosing precision for bolus deliveries with water and insulin shows a high repeatability of dosed package volumes. The pumps show a mean standard deviation of only 0.02 mg for 0.5 mg packages, and therefore, stay below the generally accepted 5% deviation, even for this extremely small amount. The high precision enables the combination with higher concentrated medication and is the foundation for the development of an extremely miniaturized patch pump.

Assessment of colour and tannin extraction in Tempranillo and Cabernet-Sauvignon using small-scale fermentation vessels

Researchers typically perform winemaking experiments using small volumes of grapes. This study examined which small-vessel volume (10, 25, 50 and 100 L) gives better repeatability during red winemaking extraction of colour and tannin in research studies. Few studies have actually evaluated the repeatability of small-scale fermentations using two varieties of different phenolic potential: Tempranillo and Cabernet-Sauvignon. We investigated how volume size may affect the composition of colour and tannins for these two varieties and result in potentially different phenolic contents. Furthermore, for each variety, we compared the small scale vessel with a commercial fermentation using a 2.500 L capacity. 50 L tanks resulted in optimum extraction of phenols and colour. High repeatability was observed for alcohol content, pH and total acidity, anthocyanins, and procyanidins for both varieties amongst vessel sizes. Kinetics of fermentation performed faster in big berry driven grapes (Tempranillo) regardless of the volume. Instead, for small berry grapes (Cabernet-Sauvignon), vessel size affected the kinetics or fermentation and therefore the extraction can be altered. Very high repeatability for the alcohol by volume, pH and total acidity (CV ≤ 7 %) as well as anthocyanins and procyanidins by HPLC (15 % ≤ CV ≤ 20 %) for both varieties in all volume sizes. This research provides a solid basis for validating the reproducibility of small-scale fermentations of two red grapevines with different phenolic potential and sheds new light on the potential and limitations of small-scale winemaking.