Time-Temperature Superposition Principle in Shearing Tests Compared to Tension Conditions for Polymers Close to Glass Transition

The well-known principle of time-temperature superposition (TTS) is of prime interest for polymers close to their glass transition. First demonstrated in the range of linear viscoelasticity, it has been more recently extended to large deformations in tension. However, shear tests were not yet addressed. The present study depicted TTS in shearing conditions and compared it to results in tensile conditions both for low and high strains for a polymethylmethacrylate (PMMA) of different molar masses. The main objectives were to enlighten the relevance of the principle of time-temperature superposition for shearing at high strain and to discuss the way shift factors should be determined. It was suggested that shift factors could be dependent on compressibility, which should be taken into account when addressing various types of complex mechanical loadings.

Adhesive Strength in Dentin Conditioned with 18% Ethylenediaminetetraacetic Acid versus 35% Phosphoric Acid: In Vitro Study with 1-Year Artificial Aging

The success and longevity of a resin composite restoration is determined by its good bonding to the tooth structure, with the adhesion being a challenge to dentin due to its complexity and structural heterogeneity. The present study aimed to compare the adhesive strength of dentin conditioned with 18% ethylenediaminetetraacetic acid (EDTA) versus 35% phosphoric acid (H3PO4) in human premolars. Materials and Methods: This in vitro experimental study was performed on 40 human premolars. The occlusal thirds were sectioned and randomly placed into four groups according to the type of dentin conditioning: Group 1 (control), Group 2 (18% EDTA), Group 3 (35% H3PO4) and Group 4 (18% EDTA plus 35% H3PO4). Then, 10,000 thermocycles between 5 +/− 2 °C and 55 +/− 2 °C were applied. Adhesive strength was tested by shearing with a digital universal testing machine at a crosshead speed of 0.75 mm/min. The values obtained were analyzed in megapascals (MPa). The mean and standard deviation were used as measures of central tendency and dispersion. In addition, a one-factor intergroup ANOVA test was applied with Tukey’s post hoc test considering a significance level of p < 0.05. Results: The 18% EDTA and 18% EDTA plus 35% H3PO4 showed significantly higher adhesive strength compared to the control group that did not receive dentin conditioning (p = 0.047 and p < 0.001, respectively). However, the group conditioned with 18% EDTA did not present significant differences compared to the group conditioned with 35% H3PO4 (p = 0.997). In addition, the group conditioned with 18% EDTA plus 35% H3PO4 showed significantly higher adhesive strength compared to the groups conditioned with 18% EDTA (p = 0.002) and 35% H3PO4 (p = 0.001). Conclusion: The adhesion of bulk fill resin composite to dentin was favorable when preconditioning was performed using 18% EDTA followed by 35% H3PO4. In contrast, when both etchants were used separately, the bulk fill resin composite showed similar bond strength values in both cases, but significantly lower compared to their sequential application.

Acute Stress Response of Sheep to Shearing Procedures: Dynamic Change of Cortisol Concentration and Protein Electrophoretic Pattern

The current study aimed to investigate the influence of acute stress by shearing procedures on hematological parameters, serum cortisol concentration and serum protein electrophoretic pattern in Comisana sheep. A total of 20 not pregnant and not lactating adult ewes, aged 3−4 years old and with a mean bodyweight of 55.50 ± 3.50 kg, were enrolled in the study. From each animal, blood samples were collected before shearing (TPRE) and 5 (TPOST5) and 60 (TPOST60) minutes after the end of the shearing procedure in order to assess the values of hematological parameters, serum cortisol, total proteins and protein fractions, including albumin, α-, β1-, β2- and γ-globulins. According to statistical analysis results, albumin values were lower at TPOST60 than TPOST5 (p < 0.01), whereas α- and β2-globulins and the A/G ratio were higher at TPOST60 with respect to TPRE (p < 0.01) and TPOST5 (p < 0.01). A higher serum concentration of cortisol was found at TPOST5 and TPOST60 than TPRE (p < 0.01), and at TPOST60 than TPOST5 (p < 0.01). The serum cortisol values were negatively correlated with the serum values of albumin, β1-globulins and A/G ratio at TPOST60, and positively correlated with α- and β2-globulins at TPOST5 and TPOST60. The decrease in the albumin concentration and the increase in the α- and β2-globulins observed in ewes after shearing with respect to the baseline values suggests an acute phase response in shorn ewes. Additionally, the correlation found between the serum cortisol concentration and the serum protein fractions confirmed the immunomodulatory effect of this hormone, emphasizing the linkage between the endocrine and immune systems during an acute stress condition.

An inexpensive, simple, and effective method of genome DNA fragmentation for NGS libraries

NGS-library preparation for whole-genome sequencing (WGS) starts with DNA fragmentation, and sonication is a physical approach used most often due to its simplicity and reproducibility. However, the commercially available Covaris instrument has a high price for both the device and consumables. Here we describe our in-house method of DNA shearing by sonication with small (100-600 µm) glass beads and an ultrasonic bath. The fragmentation conditions were optimized for the bacterial WGS with ∼550 bp fragment size (the ultrasonic bath water temperature 5-10 °C, glass beads 0.06 g, the fragmentation time 50 seconds), and for human DNA with ∼250 bp (fragmentation with the same parameters for 4 minutes). Fragmentation results were compared with the Covaris instrument for preparing several bacterial NGS libraries for Illumina NGS platforms by several characteristics. We obtained close mean fragment lengths (523-623 vs 480-646), similar mono- and dinucleotide specificity of shearing, and comparable indicators of read alignment and de novo assembly for both methods. Thus, the described method is a new fast, and effective DNA fragmentation approach that can be used in different WGS applications.

Degradation of Exopolysaccharides from Lactic Acid Bacteria by Thermal, Chemical, Enzymatic and Ultrasound Stresses

During isolation, exopolysaccharides (EPS) from lactic acid bacteria are subject of thermal, chemical, enzymatic or ultrasound stress of different intensity that may affect macromolecular properties, for instance molecular mass or (intrinsic) viscosity. These parameters are, however, crucial, as they are associated with the technofunctional potential of EPS replacing commercial thickeners in nonfermented products. The aim of this study was to systematically examine treatments EPS are usually exposed to during isolation and to investigate the underlying degradation mechanisms. Solutions (1.0 g/L) of EPS from Streptococcus thermophilus, isolated as gently as possible, and commercial dextran were analyzed for molecular mass distributions as representative measure of molecule alterations. Generally, acid, excessive heat and ultrasonication, intensified by simultaneous application, showed EPS degradation effects. Thus, recommendations are given for isolation protocols. Ultrasonic degradation at 114 W/cm² fitted into the random chain scission model and followed third- (S. thermophilus EPS) or second-order kinetics (dextran). The degradation rate constant reflects the sensitivity to external stresses and was DGCC7710 EPS > DGCC7919 EPS > dextran > ST143 EPS. Due to their exceptional structural heterogeneity, the differences could not be linked to individual features. The resulting molecular mass showed good correlation (r² = 0.99) with dynamic viscosity.

Binary Amplitude Reflection Gratings for X-ray Shearing and Hartmann Wavefront Sensors

New, high-coherent-flux X-ray beamlines at synchrotron and free-electron laser light sources rely on wavefront sensors to achieve and maintain optimal alignment under dynamic operating conditions. This includes feedback to adaptive X-ray optics. We describe the design and modeling of a new class of binary-amplitude reflective gratings for shearing interferometry and Hartmann wavefront sensing. Compact arrays of deeply etched gratings illuminated at glancing incidence can withstand higher power densities than transmission membranes and can be designed to operate across a broad range of photon energies with a fixed grating-to-detector distance. Coherent wave-propagation is used to study the energy bandwidth of individual elements in an array and to set the design parameters. We observe that shearing operates well over a ±10% bandwidth, while Hartmann can be extended to ±30% or more, in our configuration. We apply this methodology to the design of a wavefront sensor for a soft X-ray beamline operating from 230 eV to 1400 eV and model shearing and Hartmann tests in the presence of varying wavefront aberration types and magnitudes.

The Impact of Draping Effects on the Stiffness and Failure Behavior of Unidirectional Non-Crimp Fabric Fiber Reinforced Composites

Unidirectional non-crimp fabrics (UD-NCF) are often used to exploit the lightweight potential of continuous fiber reinforced plastics (CoFRP). During the draping process, the UD-NCF fabric can undergo large deformations that alter the local fiber orientation, the local fiber volume content (FVC) and create local fiber waviness. Especially the FVC is affected and has a large impact on the mechanical properties. This impact, resulting from different deformation modes during draping, is in general not considered in composite design processes. To analyze the impact of different draping effects on the mechanical properties and the failure behavior of UD-NCF composites, experimental results of reference laminates are compared to the results of laminates with specifically induced draping effects, such as non-constant FVC and fiber waviness. Furthermore, an analytical model to predict the failure strengths of UD laminates with in-plane waviness is introduced. The resulting stiffness and strength values for different FVC or amplitude to wavelength configurations are presented and discussed. In addition, failure envelopes based on the PUCK failure criterion for each draping effect are derived, which show a clear specific impact on the mechanical properties. The findings suggest that each draping effect leads to a “new fabric” type. Additionally, analytical models are introduced and the experimental results are compared to the predictions. Results indicate that the models provide reliable predictions for each draping effect. Recommendations regarding necessary tests to consider each draping effect are presented. As a further prospect the resulting stiffness and strength values for each draping effect can be used for a more accurate prediction of the structural performance of CoFRP parts.

Soft Porous Blade Printing of Nonfullerene Organic Solar Cells

Developing scalable and robust processing methods with low material waste remains a challenge for organic solar cells (OSCs) to become a practical renewable energy source. Here, we present a novel low-cost processing approach termed as soft porous blade printing (SPBP), which uses a layer of soft porous material such as filter paper as the printing blade. The inherent porous microstructure of the blade offers high shear rates that facilitate the alignment, crystallization, and orientation of active materials during printing. Moreover, by eliminating the suspended liquid meniscus, SPBP relaxes the stringent requirement of gap control and enables continuous ink delivery for uninterrupted film fabrication with adjustable thickness. Higher photovoltaic performances are achieved in the SPBP-printed OSCs than those of the spin-coated counterparts for two nonfullerene-acceptor active-layer systems (Y6:PM6 and PTQ10:IDIC). Y6:PM6 cells printed by SPBP without any additive exhibit power conversion efficiencies up to 14.75%, which is among the highest reported to date for non-spin-coated OSCs.

A population balance model to modulate shear for the control of aggregation in Taxus suspension cultures

Cellular aggregation in plant suspension cultures directly affects the accumulation of high value products, such as paclitaxel from Taxus. Through application of mechanical shear by repeated, manual pipetting through a 10 ml pipet with a 1.6 mm aperture, the mean aggregate size of a Taxus culture can be reduced without affecting culture growth. When a constant level of mechanical shear was applied over eight generations, the sheared population was maintained at a mean aggregate diameter 194 μm lower than the unsheared control, but the mean aggregate size fluctuated by over 600 μm, indicating unpredictable culture variability. A population balance model was developed to interpret and predict disaggregation dynamics under mechanical shear. Adjustable parameters involved in the breakage frequency function of the population balance model were estimated by nonlinear optimization from experimentally measured size distributions. The optimized model predictions were in strong agreement with measured size distributions. The model was then used to determine the shear requirements to successfully reach a target aggregate size distribution. This model will be utilized in the future to maintain a culture with a constant size distribution with the goal of decreasing culture variability and increasing paclitaxel yields.

Clinical, behavioral and biochemical alterations due to shearing stress in Ossimi sheep

The effects of shearing on behavioral patterns, antioxidants, and inflammatory and stress biomarkers was investigated in Ossimi sheep. Clinical parameters and behavioral patterns were recorded, and serum samples were collected pre-shearing and 1, 5, 10 and 15 days post-shearing from 60 Ossimi sheep. The results revealed that grooming and standing idle frequencies were significantly (P<0.01) increased post-shearing. There were significant (P<0.01) increases in IL-6, cortisol, and MDA detected from the 1st to the 10th day post-shearing compared to pre-shearing values. IL-2 and TNF-α significantly (P<0.01) increased from the 1st until the 5th day post-shearing compared to pre-shearing values, while significant (P<0.01) decreases in the values of catalase from the 1st until the 5th day post-shearing compared to pre-shearing values were recorded. Regarding to glutathione reductase, there was a significant (P<0.01) decrease from the 1st until the 10th day post-shearing compared to pre-shearing values. Shearing leads to significant changes in antioxidants, inflammatory, stress biomarkers, and some behaviors in sheep.

Charge-Transport Anisotropy in a Uniaxially Aligned Diketopyrrolopyrrole-Based Copolymer

Aligned films of a semiconducting DPP-based copolymer exhibit highly anisotropic charge transport with a band-like temperature dependence along the alignment direction and hole mobilities of up to 6.7 cm(2) V(-1) s(-1) . X-ray diffraction measurements reveal an exceptional degree of in-plane alignment, high crystallinity, and a dominant face-on orientation of the polymer backbones. The surprising charge-transport properties are interpreted in a tie-chain model consistent with anisotropic activation energies.

New methods for evaluating physical and thermal comfort properties of orthotic materials used in insoles for patients with diabetes

Orthotic insoles are commonly used in the treatment of the diabetic foot to prevent ulcerations. Choosing suitable insole material is vital for effective foot orthotic treatment. We examined seven types of orthotic materials. In consideration of the key requirements and end uses of orthotic insoles for the diabetic foot, including accommodation, cushioning, and control, we developed test methods for examining important physical properties, such as force reduction and compression properties, insole-skin friction, and shear properties, as well as thermal comfort properties of fabrication materials. A novel performance index that combines various material test results together was also proposed to quantify the overall performance of the insole materials. The investigation confirms that the insole-sock interface has a lower coefficient of friction and shearing stress than those of the insole-skin interface. It is also revealed that material brand and the corresponding density and cell volume, as well as thickness, are closely associated with the performance of moisture absorption and thermal comfort. On the basis of the proposed performance index, practitioners can better understand the properties and performance of various insole materials, thus prescribing suitable orthotic insoles for patients with diabetic foot.

Displaced intra-articular fractures involving the volar rim of the distal radius

PURPOSE

To describe the features of displaced intra-articular fractures confined to the volar rim of the distal radius and compare outcomes after their operative fixation to complete intra-articular and extra-articular fractures treated with operative fixation.

METHODS

A total of 627 distal radius fractures were treated over a 6-year period. Twenty-eight patients had volar rim fractures (type 23-B3, as classified by the Orthopaedic Trauma Association [OTA]), all treated with operative reduction and fixation using a volar buttress plate. Clinical outcome information including radiographs, Short Form-36 health survey, and Disabilities of the Arm, Shoulder, and Hand questionnaire were collected at regular postoperative intervals. Patients with volar rim fractures were compared with patients who sustained other types of operatively managed distal radius fractures (OTA types 23-A, 23-B1/B2, and 23-C).

RESULTS

The most common type of volar rim fracture consisted of a single large fragment (OTA 23-B3.2; 46%), followed by comminuted fractures (OTA 23-B3.3; 36%). Restoration of radiographic parameters was similar between groups except for an increased volar tilt in volar rim fractures compared with group 23-B1/B2. Active wrist and finger motion improved in all groups except for wrist extension, which was less in the 23-B1/B2 groups. The 23-B1/B2 group had the greatest pain and worst Short Form-36 scores. Disabilities of the Arm, Shoulder, and Hand questionnaire scores were similar and without differences between groups.

CONCLUSIONS

Our data suggest that patients with volar rim distal radius fractures can expect a rapid return to function with minimal risk for complications and have outcomes similar to other types of operatively treated distal radius fractures. Further investigation of type 23-B fractures (23-B1/B2) is warranted owing to evidence of diminished outcomes.