pET expression vector customized for efficient seamless cloning

Here we present a modification of the widely used pET29 expression vector for use in rapid and straightforward parallel cloning via a gene replacement and Golden Gate strategy. The modification can be applied to other expression vectors for Gram-negative bacteria. We have used the modified vectors to clone large numbers of bacterial natural enzyme variants from genomic and metagenomic sources for applications in biocatalysis

Multiscale description of carbon-supersaturated ferrite in severely drawn pearlitic wires

AbstractA multiscale simulation approach based on atomistic calculations and a discrete diffusion model is developed and applied to carbon-supersaturated ferrite, as experimentally observed in severely deformed pearlitic steel. We employ the embedded atom method and the nudged elastic band technique to determine the energetic profile of a carbon atom around a screw dislocation in bcc iron. The results clearly indicate a special region in the proximity of the dislocation core where C atoms are strongly bound, but where they can nevertheless diffuse easily due to low barriers. Our analysis suggests that the previously proposed pipe mechanism for the case of a screw dislocation is unlikely. Instead, our atomistic as well as the diffusion model results support the so-called drag mechanism, by which a mobile screw dislocation is able to transport C atoms along its glide plane. Combining the C-dislocation interaction energies with density-functional-theory calculations of the strain dependent C formation energy allows us to investigate the C supersaturation of the ferrite phase under wire drawing conditions. Corresponding results for local and total C concentrations agree well with previous atom probe tomography measurements indicating that a significant contribution to the supersaturation during wire drawing is due to dislocations

Advanced data mining in field ion microscopy

Field ion microscopy (FIM) allows to image individual surface atoms by exploiting the effect of an intense electric field. Widespread use of atomic resolution imaging by FIM has been hampered by a lack of efficient image processing/data extraction tools. Recent advances in imaging and data mining techniques have renewed the interest in using FIM in conjunction with automated detection of atoms and lattice defects for materials characterization. After a brief overview of existing routines, we review the use of machine learning (ML) approaches for data extraction with the aim to catalyze new data-driven insights into high electrical field physics. Apart from exploring various supervised and unsupervised ML algorithms in this context, we also employ advanced image processing routines for data extraction from large sets of FIM images. The outcomes and limitations of such routines are discussed, and we conclude with the possible application of energy minimization schemes to the extracted point clouds as a way of improving the spatial resolution of FIM

Differential toxicological effects of natural and synthetic sources and enantiomeric forms of limonene on mosquito larvae

Common fragranced consumer products, such as cleaning supplies and personal care products, emit chiral compounds such as limonene that have been associated with adverse effects on human health. However, those same compounds abound in nature, and at similar concentrations as in products, but without the same apparent adverse human health effects. We investigated whether different types of limonene may elicit different biological effects. In this study, we investigated the mortality rate of mosquito larvae in response to changes in their environment. Specifically, we tested different sources of naturally occurring R-limonene and chemically synthetized limonene, containing one of its enantiomeric forms (R-, S-) in mortality bioassays with Aedes aegypti mosquito larvae. We found that a natural source of limonene extracted from oranges induced lower mortality of mosquito larvae compared to synthetic sources at the same concentration. However, enantiomeric forms did not differ in their effects on mortality. Our results provide novel evidence that natural sources of a chemical can cause lower rates of mortality than synthetic sources

Volatile chemical emissions from essential oils with therapeutic claims

Essential oils emit many volatile organic compounds (VOCs), with some considered potentially hazardous. However, little is known about specific emissions from essential oils that make therapeutic claims for health and well-being. This study investigated VOCs emitted from 14 commercially available essential oils with therapeutic claims, such as beneficial for coughs, colds, flus, relaxation, sleep, tension, headaches, stress, or skin irritation. The essential oils were selected from different brands and types, such as tea tree oil, lavender oil, eucalyptus oil, geranium oil, peppermint oil, bergamot oil, orange oil, and oil blends. Analyses were performed using headspace gas chromatography/mass spectrometry (GC/MS). The analyses found 1034 VOCs emitted from the 14 essential oils, representing 378 VOC identities. The most prevalent VOCs (in more than 90% of the oils) were acetaldehyde, alpha-phellandrene, alpha-pinene, camphene, limonene, methanol, terpinolene, 3-carene, acetone, beta-phellandrene, ethanol, and gamma-terpinene. Among the 1034 VOCs emitted, 251 VOCs, representing 60 VOC identities, are classified as potentially hazardous. The most prevalent potentially hazardous VOCs were acetaldehyde, limonene, methanol, acetone, ethanol, and 3-carene. Toluene was found in more than 70% of the essential oils. Each of the essential oils emitted 9 or more potentially hazardous VOCs. Fewer than 1% of all VOCs identified and fewer than 1% of all potentially hazardous VOCs were listed on any essential oil label, safety data sheet, or website. Results from this study provide new findings on VOC emissions from essential oils with therapeutic claims, which can help to improve public awareness about potential exposures and risks

Volatile chemical emissions from fragranced baby products

Fragranced consumer products have been associated with adverse effects on human health. Babies are exposed to a variety of fragranced consumer products, which can emit numerous volatile organic compounds (VOCs), some considered potentially hazardous. However, fragranced baby products are exempt from disclosure of all ingredients. Consequently, parents and the public have little information on product emissions. This study investigates VOCs emitted from a range of fragranced baby products, including baby hair shampoos, body washes, lotions, creams, ointments, oils, hair sprays, and fragrance. The products were analysed using gas chromatography/mass spectrometry (GC/MS) headspace analysis. Of the 42 baby products tested, 21 products made claims of green, organic, or all-natural. Results of the analysis found 684 VOCs emitted collectively from the 42 products, representing 228 different VOCs. Of these 684 VOCs, 207 are classified as potentially hazardous under federal regulations, representing 43 different VOCs. The most common VOCs emitted were limonene, acetaldehyde, ethanol, alpha-pinene, linalool, beta-myrcene, acetone, and beta-pinene. A comparison between ingredients emitted and ingredients listed reveals that only 5% of the 684 VOCs, including 12% of 207 potentially hazardous VOCs, were listed on the product label, safety data sheet, or website. More than 95% of both green and regular products emitted one or more potentially hazardous VOCs. Further, emissions of the most prevalent VOCs from green, organic, or all-natural products were not significantly different from regular products. Results from this study can help improve public awareness about emissions from baby products, with the aim to reduce pollutant exposure and potential adverse effects on babies

Volatile chemical emissions from car air fresheners

Air fresheners, used in a variety of indoor environments, emit a range of volatile chemicals, including some classified as hazardous. However, little is known about the emissions from air fresheners designed for use in cars. This study investigates the volatile organic compounds emitted from car air fresheners, identifies potentially hazardous compounds, compares emissions between so-called natural and regular versions, and assesses whether ingredients are disclosed. Using gas chromatography/mass spectrometry, 12 car air fresheners were analyzed for their volatile emissions. Air freshener types included car vent clips, wraps, hanging ornaments, cans, and spray. Results reveal that the air fresheners collectively emitted 546 VOCs with 30 VOCs classified as potentially hazardous. All air freshener types emitted one or more potentially hazardous compounds. Comparing regular air fresheners with so-called natural or green air fresheners, no significant difference was found in the emissions of hazardous compounds. Notably, all products emitted at least one VOC classified as potentially hazardous. Among all of the 546 compounds emitted, fewer than 2% of all VOCs, and none of the potentially hazardous VOCs, were disclosed on any product label or safety data sheet. This study reveals that car air fresheners can be a source of exposure to numerous volatile compounds, including potentially hazardous VOCs, most of which are undisclosed. Of particular concern for human exposure is the small and enclosed breathing space within vehicles, as well as involuntary exposure in commercial vehicles such as taxi cabs and rideshares

Continuous thickening of activated sludge by electro-flotation

The present study was conducted for thickening of activated sludge by continuous electro-flotation (EF) process. The effects of some key factors such as initial pH, current density, operating time, electrode type (stainless steel and graphite) and operation conditions on the sludge thickening by determine of sludge volume reduction (SVR) and sludge solid concentration (SSC) and as well as removal of chemical oxygen demand (COD), total solids (TS), total suspended solids (TSS) and color were investigated. The results showed that the process has a good efficiency. The highest amount of SVR efficiency (89.3) and SSC (38 g L-1) were achieved at current density of 8 mA cm(-2) in 15 min for stainless steel. Moreover, as surface/volume ratio increased, better thickening happened because increases both mass transfer and electro-generation of O-2 and H-2 at the surface of electrodes in low applied current density. Accordingly, consumed electrical energy was 0.15-1 kW h m(-3). Although suitable cell design is entirely essential, the use of chemicals and temperature increase are not effective. Consequently, EF is a comparatively appropriate process for thickening; in the water separated from the process, the amounts pertaining to COD, TS, TSS and color were respectively 112, 1601, 140 mg L-1 and 5 TCU which are useable for subsequent different consumptions. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved

Deformation-Induced Martensite: A New Paradigm for Exceptional Steels

Atom-probe tomography (APT) and synchrotron X-ray diffraction (XRD) were combined to study the carbon supersaturation of ferrite for two pearlitic steel-wire compositions, eutectoid and hypereutectoid. The samples were cold-drawn at different strains up to true drawing strains for the eutectoid steel and the hypereutectoid steel, respectively. The wire diameters range from 1.7 mm down to 0.058 mm for the eutectoid steel and from 0.54 mm down to 0.02 mm for the hypereutectoid steel. The findings reveal that cold-drawing of pearlitic steel wires leads to a carbon-supersaturated ferrite causing a spontaneous tetragonal distortion of the ferrite unit cell through a strain-induced deformation driven martensitic transformation. We fi nd that the drawing process induced a significant increase in the carbon content inside the originally nearcarbon-free ferrite until a steady state is approached at drawing strains larger than ca. 4 for the wires. The change of carbon concentration in the ferrite grains during the drawing process is closely related to the tetragonal distortion of the ferrite unit cell

Effect of natural and calcined halloysite clay minerals as low-cost additives on the performance of 3D-printed alkali-activated materials

Crown Copyright © 2022. This study investigates the effects of natural and calcined halloysite clay minerals (“NH” and “CH”, respectively) on the performance of 3D printed alkali-activated materials (AAMs). Halloysite clay minerals are selected as they are low-cost and abundantly available. At first, different characterisation techniques were employed to characterise the NH and CH additives. Mechanical performance, extrusion window, and shape stability of several AAM formulations containing various dosages (0.5 wt% to 5 wt%) of the NH and CH additives were evaluated. The best-performing mixtures in terms of fresh and hardened properties namely, NH-1.5 and CH-1.5 mixtures (containing 1.5 wt% of NH and CH additives, respectively) were then selected for 3D printing. The results showed that the CH-1.5 mixture exhibited enhanced shape stability, buildability, and mechanical properties as compared to the control mixture. The flexural and compressive strengths of 3D printed CH-1.5 samples were 88% and 40%, respectively higher than those of the printed control samples. Using the CH-1.5 mixture, a twisted column with an intricate shape was printed to verify the suitability of the developed CH-modified AAM for the construction of complex structures. This study establishes the use of halloysite clay minerals as low-cost additives for enhancing the mechanical properties and printing performance of AAMs.European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement ID: 101029471; National Science Centre, Poland, within Project No. 2020/39/D/ST8/00975 (SONATA-16)