Effect of Upper-Cycle Temperature on the Load-Biased, Strain-Temperature Response of NiTi

Over the past decade, interest in shape-memory-alloy based actuators has increased as the primary benefits of these solid-state devices have become more apparent. However, much is still unknown about the characteristic behavior of these materials when used in actuator applications. Recently, we showed that the maximum temperature reached during thermal cycling under isobaric conditions could significantly affect the observed mechanical response of NiTi (55?wt?pct?Ni), especially the amount of transformation strain available for actuation and thus work output. The investigation we report here extends that original work to (1) ascertain whether increases in the upper-cycle temperature would produce additional changes in the work output of the material, which has a stress-free austenite finish temperature of 386?K (113?°C), and (2) determine the optimum cyclic conditions. Thus, isobaric, thermal-cycle experiments were conducted on the aforementioned alloy at various stresses from 50?to 300?MPa using upper-cycle temperatures of 438?K, 473?K, 503?K, 533?K, 563?K, 593?K, and 623?K (165?°C, 200?°C, 230?°C, 260?°C, 290?°C, 320?°C, and 350?°C). The data indicated that the amount of applied stress influenced the transformation strain, as would be expected. However, the maximum temperature reached during the thermal excursion also plays an equally significant role in determining the transformation strain, with the maximum transformation strain observed during thermal cycling to 563?K (290?°C). In situ neutron diffraction at stress and temperature showed that the differences in transformation strain were mostly related to changes in martensite texture when cycling to different upper-cycle temperatures. Hence, understanding this effect is important to optimizing the operation of SMA-based actuators and could lead to new methods for processing and training shape-memory alloys for optimal performance.     

The role of milk in the British diet

Milk and foods made from milk have been part of the British diet for the last 3500 years. They constitute one of the four main food groups that together comprise a healthy balanced diet, providing significant amounts of protein and most micronutrients, including calcium, B-group vitamins (particularly riboflavin and B₁₂, but also thiamin, niacin, B₆ and folate), vitamin A, iodine, magnesium, phosphorus, potassium and zinc. Milk and dairy foods can increase the nutrient density of the diet and play a pivotal role in ensuring that dietary intakes are nutritionally adequate. They can also help to improve bone and dental health and possibly protect against hypertension and colon cancer.     

Effect of Calcium on Lead in Soft-Water Distribution Systems

Meeting the lead rule action level for drinking water can be difficult for soft-water systems. One concern in these systems is the formation of particulate or colloidal lead that is difficult to remove from the aqueous phase. In this preliminary study, batch and pipe-loop systems are used to assess the effect of calcium addition on lowering the concentration of particulate or colloidal lead. The addition of calcium at levels as low as 5 mg∕L reduced zeta potential of lead-bound colloids and in some cases resulted in a reduction of total Pb concentration.     

Single Component Self‐Assembled Monolayers of Aromatic Azo‐Biphenyl: Influence of the Packing Tightness on the SAM Structure and Light‐Induced Molecular Movements

Aiming at modulating the packing density within functional self‐assembled monolayers (SAMs), two azo‐biphenyl derivatives AZO1 and AZO2 comprising a terminal sulfur anchor group have been designed and synthesized. While AZO1 allows for a coplanar arrangement of both biphenyl subunits, additional steric repulsion due to two methyl side groups attached to the footing biphenyl of AZO2 results in an increased intermolecular distance within the SAM, providing additional free volume. SAMs of both derivatives on gold and platinum substrates have been formed and thoroughly investigated by photoelectron (XPS) and near‐edge absorption fine structure (NEXAFS) spectroscopy as well as cyclic voltammetry and scanning tunneling microscopy. These measurements confirmed the formation of tightly packed SAMs for AZO1 , while AZO2 formed SAMs consisting of less organized and more loosely packed molecules. Optical investigations of both azo derivatives in solution as well as their SAMs displayed efficient photoisomerization in solution and in SAMs. Comparable maximal cis/trans ratios of ca. 0.9 have been observed in all cases upon irradiation at λ = 370 and 360 nm for AZO1 and AZO2 , respectively. The thermally induced cis → trans back reaction on AZO1 was found to be slower by a factor of 3 in SAMs as compared to solution, while AZO2 displayed comparable rates of the back reaction in both environments. This behavior can be explained by the different nature of molecular isomerization in the two SAM systems: whereas the isomerization in AZO1 SAMs takes place in a highly coordinated, collective way and involves many adjacent molecules, AZO2 species behave rather individually even packed in SAMs, such that their isomerization process is similar in SAMs and in solutions.     

Short- and medium-chain chlorinated paraffins in biota from the European Arctic -- differences in homologue group patterns

Congener and homologue group patterns of chlorinated paraffins (CPs) in biota can be influenced by different processes, but these are not well studied yet. Short- (SCCPs) and medium-chain chlorinated paraffins (MCCPs) were quantified in liver from Arctic char and seabirds (little auk and kittiwake) collected at Bear Island (European Arctic) as well as in cod from Iceland and Norway. CP concentrations were between 5 and 88 ng/g wet weight (ww) for SCCPs and between 5 and 55 ng/g ww for MCCPs with one exception of 370 ng/g measured in a liver sample from little auk. The SCCP homologue group patterns were compared with those of technical mixtures and of SCCPs present in cod liver from the Baltic Sea. The latter showed a more common SCCP homologue distribution (sum of C(11) and C(12)>60%) in contrast to cod liver from the Northwest of Europe, which had a high abundance of C(10) and C(12) congeners. Seabirds from Bear Island contained an equally distributed SCCP homologue group pattern. In Arctic char, the SCCP distribution was closer to technical products, but with a high proportion (average of 18.9%) of C(10) congeners. A comparison of C(10)/C(12) ratios confirmed the higher abundance of C(10) congeners in samples from higher latitudes. For the first time, MCCPs could be detected in Arctic samples. The average proportion of C(14) congeners was 65.8%. The C(14)/C(15) abundance ratio was similar to technical mixtures. High-chlorinated CPs (Cl(>7)) were also detectable. The average chlorine content of the SCCPs was 61.9% (59.0-63.3%), and that of the MCCPs 55.8% (54.5-57.4%).     

Performance evaluation of domino logic circuits for wide fan-in gates with FinFET

Microsystem Technologies - Power dissipation, propagation delay and noise are major issues in digital circuit design. In this paper, a new leakage-tolerant domino circuit is presented which has...     

On the correlation between stiffness and strength properties of anisotropic laminates

This paper focuses on the analytical formulation of laminate-level failure criteria which are expressed (under a unified matrix formulation) in the framework of the first-order shear deformation theory (FSDT) in order to take into account the influence of the transverse shear stresses on the failure mechanisms. The proposed unified formulation relies on the utilization of the polar formalism generalized to the FSDT framework: in this background, all the considered criteria are stated in terms of tensor invariants. Furthermore, an important theoretical result is proven: the existence of a set of analytical relationships between the laminate strength and stiffness invariants.     

Pichia pastoris protease-deficient and auxotrophic strains generated by a novel,user-friendly vector toolbox for gene deletion

Targeted gene knockouts play an important role in the study of gene function. For the generation of knockouts in the industrially important yeast Pichia pastoris, several protocols have been published to date. Nevertheless, creating a targeted knockout in P. pastoris still is a time-consuming process, as the existing protocols are labour intensive and/or prone to accumulate nucleotide mutations. In this study, we introduce a novel, user-friendly vector-based system for the generation of targeted knockouts in P. pastoris. Upon confirming the successful knockout, respective selection markers can easily be recycled. Excision of the marker is mediated by Flippase (Flp) recombinase and occurs at high frequency (≥95%). We validated our knockout system by deleting 20 (confirmed and putative) protease genes and five genes involved in biosynthetic pathways. For the first time, we describe gene deletions of PRO3 and PHA2 in P. pastoris, genes involved in proline, and phenylalanine biosynthesis, respectively. Unexpectedly, knockout strains of PHA2 did not display the anticipated auxotrophy for phenylalanine but rather showed a bradytroph phenotype on minimal medium hinting at an alternative but less efficient pathway for production of phenylalanine exists in P. pastoris. Overall, all knockout vectors can easily be adapted to the gene of interest and strain background by efficient exchange of target homology regions and selection markers in single cloning steps. Average knockout efficiencies for all 25 genes were shown to be 40%, which is comparably high.