Cas12a (Cpf1) is a CRISPR-associated nuclease with broad utility for synthetic genome engineering, agricultural genomics, and biomedical applications. Although bacteria harboring CRISPR-Cas9 or ...CRISPR-Cas3 adaptive immune systems sometimes acquire mobile genetic elements encoding anti-CRISPR proteins that inhibit Cas9, Cas3, or the DNA-binding Cascade complex, no such inhibitors have been found for CRISPR-Cas12a. Here we use a comprehensive bioinformatic and experimental screening approach to identify three different inhibitors that block or diminish CRISPR-Cas12a-mediated genome editing in human cells. We also find a widespread connection between CRISPR self-targeting and inhibitor prevalence in prokaryotic genomes, suggesting a straightforward path to the discovery of many more anti-CRISPRs from the microbial world.
An experimental investigation of the effect of nanotube length and aggregate size on the mechanical and electrical properties of the composites was reported. Three treatments, that affect mainly the ...length and aggregate size, were applied on the CVD MWNTs before they were added into a resin matrix. They had a very clear impact on the dielectric properties of the composites and on the improvement efficiency. There was an insulator-to-conductor transition with the as-prepared MWNTs at 0.5
wt%. Regarding the mechanical properties, the addition of MWNTs increased the Young's modulus and reduced the fracture strain. In that case, the pre-treatment on MWNTs, however, had a much more moderate effect on the improvement efficiency.
Summary Objective To evaluate the efficacy of Danshen on histological parameters and antioxidative activity in the articular cartilage of rabbits with osteoarthritis (OA). Design Twenty-four rabbits ...were randomly divided into three groups (control, OA, and Danshen OA; eight rabbits per group). Anterior cruciate ligament transection (ACLT) of the left hind knees was performed in all rabbits in the OA and Danshen OA group for induction of OA. The rabbits in the control group underwent a sham operation. After surgery, 3 g/kg body weight of Danshen granules dissolved in 5 mL distilled water was administered by gastric intubation once per day and over a 6-week period to the Danshen OA group. The same volume of distilled water was administered to the OA and control groups. After 6 weeks, the medial femoral condyles and synoviums of the left hind knees in all three groups were harvested and used for histological and biochemical analyses. Results Severe articular cartilage degeneration as well as lower proteoglycan (PG) content were noted in the OA group compared to the Danshen OA group ( P < 0.05). The glutathione (GSH) levels in the synovium and articular cartilage of the rabbits in the Danshen OA group were significantly higher compared to the OA group ( P < 0.001). The malondialdehyde (MDA) levels of the synovium and articular cartilage in the Danshen OA group was markedly depleted compared to the OA group ( P < 0.001). Conclusion Danshen can prevent articular cartilage degeneration in OA through the defense against oxidative stress.
We interpret the Taylor–Green cellular vortex model in terms of the Kolmogorov length and velocity scales, in order to study the balance between aggregation and breakup of cohesive sediment in ...fine-scale turbulence. One-way coupled numerical simulations, which capture the effects of cohesive, lubrication and direct contact forces on the flocculation process, reproduce the non-monotonic relationship between the equilibrium floc size and shear rate observed in previous experiments. The one-way coupled results are confirmed by select two-way coupled simulations. Intermediate shear gives rise to the largest flocs, as it promotes preferential concentration of the primary particles without generating sufficiently strong turbulent stresses to break up the emerging aggregates. We find that the optimal intermediate shear rate increases for stronger cohesion and smaller particle-to-fluid density ratios, and we propose a simple model for the equilibrium floc size that agrees well with experimental data reported in the literature.
Abstract Purpose To investigate whether grape seed proanthocyanidins (GSP) might protect the heart against myocardial injury (MI) induced by isoproterenol (ISO), in a rat model. Methods GSP was ...administered orally to Wistar albino rats (150–180 g) in three different doses, by gastric gavage (50, 100 and 150 mg kg − 1 GSP), 6 days a week for 5 weeks. At the end of this period, all the rats, except the normal untreated rats that served as the control group, were administered ISO, 85 mg kg − 1 subcutaneously, for 2 consecutive days to induce myocardial injury. After 48 h, rats ( n = 6 per group) were anaesthetized with anesthetic ether, sacrificed and the levels of biochemical and histological observations of the heart tissues were performed. Result Our results suggest that prior administration of GSP maintained the levels of the marker enzymes (AST, ALT, LDH and CK) in all the treatment groups (GSP-50-ISO, GSP-100-ISO and GSP-150-ISO) when compared to ISO-injected rats. The entire baseline groups also showed no significant alterations in serum marker enzyme levels in comparison to that of control group. Interestingly, in this study, there was no significant change in the basal levels of myocardial TBARS, GST, SOD and CAT on administration of GSP in all the three dosages (GSP-50-BL, GSP-100-BL and GSP-150-BL). However, a significant decrease occurred in the levels of GSH and GPx in group GSP-50-BL, which in the absence of any cellular injury (as evidenced by histological studies), is considered to be non-lethal. In the ISO-injected group there was a significant rise in TBARS and a significant decrease in GSH, GPx, GST, SOD and CAT when compared to group control. The administration of GSP maintained the activities of these enzymes close to normal levels when compared to group ISO, which proves the stress stabilizing action of GSP. The biochemical and histological evidence from this study shows that 100 and 150 mg kg − 1 of GSP protected against ISO-induced myocardial injury. Conclusion This study demonstrates that GSP has a significant effect in the protection of heart against MI induced by ISO. We believe that pretreatment with GSP may contribute to developing novel strategies in the prevention and treatment of cardiotoxic effects of elevated levels of catecholamine.
Mass spectrometry-based proteomics has experienced an unprecedented advance in comprehensive analysis of proteins and posttranslational modifications, with particular technical progress in liquid ...chromatography coupled to tandem mass spectrometry (LC-MS/MS) and isobaric labeling multiplexing capacity. Here, we introduce a deep proteomics profiling protocol that combines 10-plex tandem mass tag (TMT) labeling with an optimized LC-MS/MS platform to quantitate whole proteome and phosphoproteome. The major steps include protein extraction and digestion, TMT labeling, two-dimensional liquid chromatography, TiO
-mediated phosphopeptide enrichment, high-resolution mass spectrometry, and computational data processing. This protocol routinely leads to confident quantification of more than 10,000 proteins and approximately 30,000 phosphosites in mammalian samples. Quality control steps are implemented for troubleshooting and evaluating experimental variation. Such a multiplexed robust method provides a powerful tool for dissecting proteomic signatures at the systems level in a variety of complex samples, ranging from cell culture, animal tissues to human clinical specimens.
•A two-dimensional model for the design of flow fields in VRFBs is reported.•Uniformity of vanadium ion distribution is evaluated by uniformity factors.•Pressure drop is accurately captured in ...interdigitated and serpentine flow fields.•Performance of several design of flow fields for a large cell is studied.
In this work, we report a two-dimensional mathematical model for the design of flow fields in vanadium redox flow batteries (VRFBs). The model is validated by calculating the pressure drop, distribution uniformity of vanadium ions in an interdigitated flow field and a serpentine flow field for a 9-cm2 cell. The model is then used to simulate interdigitated and a series of parallel serpentine design of flow fields in a 410-cm2 cell. It is demonstrated that with an increase in the number of parallel serpentine channels, the pumping power decreases while the distribution of vanadium ions becomes less uniform. Among the design of flow fields studied in this work, the interdigitated design performs the lowest pumping power and the most uniform distributions of vanadium ions.
Multi-walled carbon nanotube/epoxy resin composites have been fabricated. By choosing an over-aged hardener, relatively soft and ductile matrix, a rubbery epoxy resin, has been obtained. This made ...possible to evaluate the effect of nanotube addition on the whole stress-strain curve up to high strain level. The mechanical and electrical properties of the composite with different weight percentages of nanotubes have been investigated. The Young's modulus and the yield strength have been doubled and quadrupled for composites with respectively 1 and 4 wt.% nanotubes, compared to the pure resin matrix samples. Conductivity measurements on the composite samples showed that the insulator-to-conductor transition took place for nanotube concentration between 0.5% and 1 wt.%.
We investigate the dynamics of cohesive particles in homogeneous isotropic turbulence, based on one-way coupled simulations that include Stokes drag, lubrication, cohesive and direct contact forces. ...We observe a transient flocculation phase, followed by a statistically steady equilibrium phase. We analyse the temporal evolution of floc size and shape due to aggregation, breakage and deformation. Larger turbulent shear and weaker cohesive forces yield smaller elongated flocs. Flocculation proceeds most rapidly when the fluid and particle time scales are balanced and a suitably defined Stokes number is $O(1)$. During the transient stage, cohesive forces of intermediate strength produce flocs of the largest size, as they are strong enough to cause aggregation, but not so strong as to pull the floc into a compact shape. Small Stokes numbers and weak turbulence delay the onset of the equilibrium stage. During equilibrium, stronger cohesive forces yield flocs of larger size. The equilibrium floc size distribution exhibits a preferred size that depends on the cohesive number. We observe that flocs are generally elongated by turbulent stresses before breakage. Flocs of size close to the Kolmogorov length scale preferentially align themselves with the intermediate strain direction and the vorticity vector. Flocs of smaller size tend to align themselves with the extensional strain direction. More generally, flocs are aligned with the strongest Lagrangian stretching direction. The Kolmogorov scale is seen to limit floc growth. We propose a new flocculation model with a variable fractal dimension that predicts the temporal evolution of the floc size and shape.
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