Probabilistic characteristics of random damage events and their quantification in acrylic bone cement

The failure of brittle and quasi-brittle polymers can be attributed to a multitude of random microscopic damage modes, such as fibril breakage, crazing, and microfracture. As the load increases, new damage modes appear, and existing ones can transition into others. In the example polymer used in this study—a commercially available acrylic bone cement—these modes, as revealed by scanning electron microscopy of fracture surfaces, include nucleation of voids, cracking, and local detachment of the beads from the matrix. Here, we made acoustic measurements of the randomly generated microscopic events (RGME) that occurred in the material under pure tension and under three-point bending, and characterized the severity of the damage by the entropy (s) of the probability distribution of the observed acoustic signal amplitudes. We correlated s with the applied stress (σ) by establishing an empirical s–σ relationship, which quantifies the activities of RGME under Mode I stress. It reveals the state of random damage modes: when ds/dσ > 0, the number of damage modes present increases with increasing stress, whereas it decreases when ds/dσ < 0. When ds/dσ ≈ 0, no new random damage modes occur. In the s–σ curve, there exists a transition zone, with the stress at the “knee point” in this zone (center of the zone) corresponding to ~30 and ~35% of the cement’s tensile and bending strengths, respectively. This finding explains the effects of RGME on material fatigue performance and may be used to approximate fatigue limit.     

Analysis of the interaction of adjacent layers of a GFRP-laminate under fatigue loading

A layer-wise strength analysis of laminates leads to realistic results not only with quasistatic but also with cyclic loading. The used fatigue strength has to be determined by experiment. Degradation models exist, used to reduce the laminate stiffness due to inter-fibre fracture (IFF) cracks. However a notch effect caused by IFF – in other words, a local increase in stress in the laminate adjacent to the laminate affected by an IFF – is not included. This leads to a premature failure of the laminate much earlier as it is predicted by a failure criteria. Performing 3-point-bending tests the notch effect was measured to obtain a more exact service life prediction. Adequate crack arresting layers are tested which will reduce the negative notch effect.     

Biochemical and Initial Structural Characterization of the Monocot Chimeric Jacalin OsJAC1

The monocot chimeric jacalin OsJAC1 from Oryza sativa consists of a dirigent and a jacalin-related lectin domain. The corresponding gene is expressed in response to different abiotic and biotic stimuli. However, there is a lack of knowledge about the basic function of the individual domains and their contribution to the physiological role of the entire protein. In this study, we have established a heterologous expression in Escherichia coli with high yields for the full-length protein OsJAC1 as well as its individual domains. Our findings showed that the secondary structure of both domains is dominated by β-strand elements. Under reducing conditions, the native protein displayed clearly visible transition points of thermal unfolding at 59 and 85 °C, which could be attributed to the lectin and the dirigent domain, respectively. Our study identified a single carbohydrate-binding site for each domain with different specificities towards mannose and glucose (jacalin domain), and galactose moieties (dirigent domain), respectively. The recognition of different carbohydrates might explain the ability of OsJAC1 to respond to different abiotic and biotic factors. This is the first report of specific carbohydrate-binding activity of a DIR domain, shedding new light on its function in the context of this monocot chimeric jacalin.     

齿轮泵在橡胶挤出工艺中的应用

齿轮泵技术在橡胶工业中的应用正取得突飞猛进的发展。橡胶挤出中使用齿轮泵有很多优点 ,如可提高产品质量和减少胶料焦烧等。事实上 ,如果多花一点时间改进和优化技术 ,同时应用更多必要的范例来了解齿轮泵的用途 ,将很难想象在下一代挤出生产线中可以不用齿轮泵。这主要是由于单螺杆挤出机有限的生产能力造成的。1　单螺杆挤出机的边界条件挤出的主要目的之一是在高生产能力和一定温度下生产具有稳定尺寸、光滑表面和精确口型的几何形状产品。为了达到这个目的 ,单螺杆挤出机的各加工步骤非常重要。它们可分成下列几个环节 :喂料、均匀加…     

Nanoscaled Biocoatings via Enzyme Mediated Autodeposition of Casein

Formation of nanoscaled monolayer protein structures via enzyme mediated autodeposition is investigated on the example of casein as protein and chymosin as enzyme. The key of this method is tethering of enzyme to the support. This ensures that destabilization and subsequent deposition of casein particles occurs only in direct proximity to the support surface. In this work, covalent enzyme coupling (with and without polymeric spacer) is applied to obtain high site‐specificity and self‐terminating properties of the autodeposition process. Direct covalent coupling results in defined deposition of monolayer films or single particles. Use of polymeric spacers increases the amount and radius of deposition by a factor of 4, due to higher mobility of enzyme and delayed self‐termination. Deposited casein structures show DMT‐moduli of 1.2–1.4 GPa, indicating higher flexibility compared to conventional casein coatings. Applications might arise in the fields of implantology and biosensor technology as well as renewable coatings.

     

Monitoring Dicer-Mediated miRNA-21 Maturation and Ago2 Loading by a Dual-Colour FIT PNA Probe Set

The inhibition of micro RNA (miRNA) maturation by Dicer and loading matured miRNAs into the RNA-induced silencing complex (RISC) is envisioned as a modality for treatment of cancer. Existing methods for evaluating maturation either focus on the conversion of modified precursors or detect mature miRNA. Whereas the former is not applicable to native pre-miRNA, the latter approach underestimates maturation when both nonmatured and matured miRNA molecules are subject to cleavage. We present a set of two orthogonally labelled FIT PNA probes that distinguish between cleaved pre-miRNA and the mature miRNA duplex. The probes allow Dicer-mediated miR21 maturation to be monitored and Ago2-mediated unwinding of the miR21 duplex to be assayed. A two-channel fluorescence readout enables measurement in real-time without the need for specialized instrumentation or further enzyme mediated amplification.     

Public Health als Beitrag zur sozialen Gerechtigkeit

Definition of the problem Health and life expectancy are strongly influenced by social factors. Even in social welfare states, there are significant health inequalities between upper and lower sections of the population. These differences are increasingly perceived as a problem of social justice. Arguments Public health conduces to the reduction of health inequalities and, thus, to promoting social justice. Even though public health measures can contribute to promoting and leveling of population health more efficiently than the provision of more medical care, they have not received as much significance in health care politics. This prioritizing in favor of medicine can be criticized as irrational. But it should be noted that medicine is of high symbolic importance for social care and social recognition not given by public health. Health inequalities are not per se socially unjust, but only if they are based on an unjust distribution of social determinants of health. These factors, e.g., income and education, are of importance for social justice irrespective of their health-related consequences. Conclusion Justice in health cannot be determined alone, but only in the context of a comprehensive theory of social justice.     

Autonomous vehicles: challenges,opportunities, and future implications for transportation policies

This study investigates the challenges and opportunities pertaining to transportation policies that may arise as a result of emerging autonomous vehicle (AV) technologies. AV technologies can decrease the transportation cost and increase accessibility to low-income households and persons with mobility issues. This emerging technology also has far-reaching applications and implications beyond all current expectations. This paper provides a comprehensive review of the relevant literature and explores a broad spectrum of issues from safety to machine ethics. An indispensable part of a prospective AV development is communication over cars and infrastructure (connected vehicles). A major knowledge gap exists in AV technology with respect to routing behaviors. Connected-vehicle technology provides a great opportunity to implement an efficient and intelligent routing system. To this end, we propose a conceptual navigation model based on a fleet of AVs that are centrally dispatched over a network seeking system optimization. This study contributes to the literature on two fronts: (i) it attempts to shed light on future opportunities as well as possible hurdles associated with AV technology; and (ii) it conceptualizes a navigation model for the AV which leads to highly efficient traffic circulations.

     

A Multi-step Virtual Screening Protocol for the Identification of Novel Non-acidic Microsomal Prostaglandin E2 Synthase-1 (mPGES-1) Inhibitors

Microsomal prostaglandin E₂ synthase-1 (mPGES-1) is a potential therapeutic target for the treatment of inflammatory diseases and certain types of cancer. To identify novel scaffolds for mPGES-1 inhibition, we applied a virtual screening (VS) protocol that comprises molecular docking, fingerprints-based clustering with diversity-based selection, protein–ligand interactions fingerprints, and molecular dynamics (MD) simulations with molecular mechanics Poisson–Boltzmann surface area (MM-PBSA) calculations. The hits identified were carefully analyzed to ensure the selection of novel scaffolds that establish stable interactions with key residues in the mPGES-1 binding pocket and inhibit the catalytic activity of the enzyme. As a result, we discovered two promising chemotypes, 4-(2-chlorophenyl)-N-[(2-{[(propan-2-yl)sulfamoyl]methyl}phenyl)methyl]piperazine-1-carboxamide ( 6 ) and N-(4-methoxy-3-{[4-(6-methyl-1,3-benzothiazol-2-yl)phenyl]sulfamoyl}phenyl)acetamide ( 8 ), as non-acidic mPGES-1 inhibitors with IC₅₀ values of 1.2 and 1.3 μm , respectively. Minimal structural optimization of 8 resulted in three more compounds with promising improvements in inhibitory activity (IC₅₀: 0.3–0.6 μm ). The unprecedented chemical structures of 6 and 8 , which are amenable to further derivatization, reveal a new and attractive approach for the development of mPGES-1 inhibitors with potential anti-inflammatory and anticancer properties.