LacO-LacI interaction in affinity adsorption of plasmid DNA

Current approaches for purifying plasmids from bacterial production systems exploit the physiochemical properties of nucleic acids in non-specific capture systems. In this study, an affinity system for plasmid DNA (pDNA) purification has been developed utilizing the interaction between the lac operon (lacO) sequence contained in the pDNA and a 64mer synthetic peptide representing the DNA-binding domain of the lac repressor protein, LacI. Two plasmids were evaluated, the native pUC19 and pUC19 with dual lacO3/lacOs operators (pUC19lacO3/lacOs), where the lacOs operator is perfectly symmetrical. The DNA-protein affinity interaction was evaluated by surface plasmon resonance using a Biacore system. The affinity capture of DNA in a chromatography system was evaluated using LacI peptide that had been immobilized to Streamline™ adsorbent. The KD-values for double stranded DNA (dsDNA) fragments containing lacO1 and lacO3 and lacOs and lacO3 were 5.7 ± 0.3 × 10 -11 M and 4.1 ± 0.2 × 10-11 M respectively, which compare favorably with literature reports of 5 × 10-10 - 1 × 10-9 M for native laCO1 and 1-1.2 × 10-10 M for lacO1 in a saline buffer. Densitometric analysis of the gel bands from the affinity chromatography run clearly showed a significant preference for capture of the supercoiled fraction from the feed pDNA sample. The results indicate the feasibility of the affinity approach for pDNA capture and purification using native protein-DNA interaction.

Affinity adsorption of plasmid DNA

The development of a protein-mediated dual functional affinity adsorption of plasmid DNA is described in this work. The affinity ligand for the plasmid DNA comprises a fusion protein with glutathione-S-transferase (GST) as the fusion partner with a zinc finger protein. The protein ligand is first bound to the adsorbent by affinity interaction between the GST moeity and gluthathione that is covalently immobilized to the base matrix. The plasmid binding is then enabled via the zinc finger protein and a specific nucleotide sequence inserted into the DNA. At lower loadings, the binding of the DNA onto the Fractogel, Sepharose, and Streamline matrices was 0.0078 ± 0.0013, 0.0095 ± 0.0016, and 0.0080 ± 0.0006 mg, respectively, to 50 μL of adsorbent. At a higher DNA challenge, the corresponding amounts were 0.0179 ± 0.0043, 0.0219 ± 0.0035, and 0.0190 ± 0.0041 mg, respectively. The relatively constant amounts bound to the three adsorbents indicated that the large DNA molecule was unable to utilize the available zinc finger sites that were located in the internal pores and binding was largely a surface adsorption phenomenon. Utilization of the zinc finger binding sites was shown to be highest for the Fractogel adsorbent. The adsorbed material was eluted with reduced glutathione, and the eluted efficiency for the DNA was between 23% and 27%. The protein elution profile appeared to match the adsorption profiles with significantly higher recoveries of bound GST-zinc finger protein.

Application of organo-beidellites for the adsorption of atrazine

The surfaces of natural beidellite were modified with cationic surfactant octadecyl trimethylammonium bromide at different concentrations. The organo-beidellite adsorbent materials were then used for the removal of atrazine with the goal of investigating the mechanism for the adsorption of organic triazine herbicide from contaminated water. Changes on the surfaces and structure of beidellite were characterised by X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and BET surface analysis. Kinetics of the adsorption studies were also carried out which show that the adsorption capacity of the organoclays increases with increasing surfactant concentration up until 1.0 CEC surfactant loading, after which the adsorption capacity greatly decreases. TG analysis reveals that although the 2.0 CEC sample has the greatest percentage of surfactant by mass, most of it is present on external sites. The 0.5 CEC sample has the highest proportion of surfactant exchanged into the internal active sites and the 1.0 CEC sample accounts for the highest adsorption capacity. The goodness of fit of the pseudo-second order kinetic confirms that chemical adsorption, rather than physical adsorption, controls the adsorption rate of atrazine.

Vision-based operations of a large industrial vehicle : autonomous hot metal carrier

Hot metal carriers (HMCs) are large forklift-type vehicles used to move molten metal in aluminum smelters. This paper reports on field experiments that demonstrate that HMCs can operate autonomously and in particular can use vision as a primary sensor to locate the load of aluminum. We present our complete system but focus on the vision system elements and also detail experiments demonstrating reliable operation of the materials handling task. Two key experiments are described, lasting 2 and 5 h, in which the HMC traveled 15 km in total and handled the load 80 times.

Liquid metal/metal oxide frameworks with incorporated Ga2O3 for photocatalysis

Solvothermally synthesized Ga2O3 nanoparticles are incorporated into liquid metal/metal oxide (LM/MO) frameworks in order to form enhanced photocatalytic systems. The LM/MO frameworks, both with and without incorporated Ga2O3 nanoparticles, show photocatalytic activitydue to a plasmonic effect where performance is related to the loading of Ga2O3 nanoparticles. Optimum photocatalytic efficiency is obtained with 1 wt% incorporation of Ga2O3 nanoparticles. This can be attributed to the sub-bandgap states of LM/MO frameworks, contributing to pseudo-ohmic contacts which reduce the free carrier injection barrier to Ga2O3.

Autonomous hot metal carrier: Navigation and manipulation with a 20 tonne industrial vehicle

This paper reports work on the automation of a hot metal carrier, which is a 20 tonne forklift-type vehicle used to move molten metal in aluminium smelters. To achieve efficient vehicle operation, issues of autonomous navigation and materials handling must be addressed. We present our complete system and experiments demonstrating reliable operation. One of the most significant experiments was five-hours of continuous operation where the vehicle travelled over 8 km and conducted 60 load handling operations. Finally, an experiment where the vehicle and autonomous operation were supervised from the other side of the world via a satellite phone network are described.

Book Review: "Metal Rules the Globe: Heavy Metal Music around the World". Durham, NC: Duke University Press.

It is rare to find an anthology that realizes the possibilities of the form. We tend to regard our edited collections as lesser siblings, and forget their special value. But at times, a subject seems to require an edited collection much more than it does a classic monograph. So it is with the subject showcased here, which concerns the global circulation, performance and consumption of heavy metal. This is a relatively new and emerging body of work, hitherto scattered disparately in the broader popular music studies, but quickly gaining status as a “studies” with the establishment of a global conference, a journal, and publication of this anthology, all in recent years. Metal Rules the Globe took the editors’ a decade to compile. That they have thought deeply about how they want the collection to speak shows through in the book’s thoughtful arrangement and design, and in the way in which they draw on the contributions herein to develop for the field a research agenda that will take it forward...

Autonomous hot metal carrier

This paper reports work involved with the automation of a Hot Metal Carrier — a 20 tonne forklift-type vehicle used to move molten metal in aluminium smelters. To achieve efficient vehicle operation, issues of autonomous navigation and materials handling must be addressed. We present our complete system and experiments demontrating reliable operation. One of the most significant experiments was five-hours of continuous operation where the vehicle travelled over 8 km and conducted 60 load handling operations. We also describe an experiment where the vehicle and autonomous operation were supervised from the other side of the world via a satellite phone network.

Transition metal layered double hydroxides for energy storage

Various types of layered double hydroxides, a type of clay, were synthesised. They were then electrochemically tested to determine whether the samples would be suitable to store energy as supercapacitors. A manganese aluminium layered double hydroxide was electrochemically tested for the first time and found to have a large capacitance.

The structures of the isomorphous potassium and rubidium salts of 4-nitrobenzoic acid and an overview of the metal complex stereochemistries of the alkali metal salt series with this ligand

The structures of the isomorphous potassium and rubidium polymeric coordination complexes with 4-nitrobenzoic acid, poly[mu2-aqua-aqua-mu3-(4-nitrobenzoato)-potassium], [K(C7H4N2O2)(H2O)2]n, (I) and poly[mu3-aqua-aqua-mu5-(4-nitrobenzoato)-rubidium], [Rb(C7H4N2O2)(H2O)2]n, (II) have been determined. In (I) the very distorted KO6 coordination sphere about the K+ centres in the repeat unit comprise two bridging nitro O-atom donors, a single bridging carboxyl O-atom donor and two water molecules, one of which is bridging. In the the Rb complex (II), the same basic MO6 coordination is found in the repeat unit but is expanded to RbO9 through a slight increase in the accepted Rb-O bond length range and includes an additional Rb-O(carboxyl) bond, completing a bidentate O,O'-chelate interaction, and additional bridging Rb-Onitro) and Rb-O(water) bonds. The comparative K-O and Rb-O bond length ranges are 2.738(3)-3.002(3)Ang. (I) and 2.884(2)-3.182(2)Ang. (II). The structure of (II) is also isomorphous as well as isostructural with the known structure of the nine-coordinate caesium 4-nitrobenzoate analogue, [Cs(C7H4N2O~2~)(H~2~O)2]n, (III) in which the Cs---O range is 3.047(4)-3.338(4)Ang. In all three complexes, common basic polymeric extensions are found, including two different centrosymmetric bridging interactions through both water and nitro groups as well as extensions along c through the p-related carboxyl group, giving a two-dimensional structure in (I). In (II) and (III), three-dimensional structures are generated through additional bridges through the nitro and water O-atoms. In all structures, both water molecules are involved in similar intra-polymer O-H...O hydrogen-bonding interactions to both carboxyl as well as water O-atom acceptors. A comparison of the varied coordination behaviour of the full set of Li-Cs salts with 4-nitrobenzoic acid is also made.

Modelling CO2 adsorption and separation on experimentally-realized B40 fullerene

Searching for efficient solid sorbents for CO2 adsorption and separation is important for developing emergent carbon reduction and natural gas purification technology. This work, for the first time, has investigated the adsorption of CO2 on newly experimentally realized cage-like B40 fullerene (Zhai et al., 2014) based on density functional theory calculations. We find that the adsorption of CO2 on B40 fullerene involves a relatively large energy barrier (1.21 eV), however this can be greatly decreased to 0.35 eV by introducing an extra electron. A practical way to realize negatively charged B40 fullerene is then proposed by encapsulating a Li atom into the B40 fullerene (Li@B40). Li@B40 is found to be highly stable and can significantly enhance both the thermodynamics and kinetics of CO2 adsorption, while the adsorptions of N2, CH4 and H2 on the Li@B40 fullerene remain weak in comparison. Since B40 fullerene has been successfully synthesized in a most recent experiment, our results highlight a new promising material for CO2 capture and separation for future experimental validation.

Generation of catalytically active materials from a liquid metal precursor

A facile route to prepare catalystically active materials from a galinstan liquid metal alloy is introduced. Sonicating liquid galinstan in alkaline solution or treating it in reducing media results in the creation of solid In/Sn rich microspheres that show catalytic activity toward both potassium ferricyanide and 4-nitrophenol reduction.

Effects of metal ion concentration on electrodeposited CuZnSn film and its application in kesterite Cu2ZnSnS4solar cells

In this study, effects of concentrations of Cu(II), Zn(II) and Sn(II) ions in the electrolytic bath solution on the properties of electrochemically deposited CuZnSn (CZT) films were investigated. Study of the composition of a CZT film has shown that the metallic content (relative atomic ratio) in the film increased linearly with increase in the metal ion concentration. It is the first time that the relationship of the compositions of the alloy phases in the co-electrodeposited CZT film with the concentration of metal ions has been revealed. The results have confirmed that the formation and content of Cu6Sn5 and Cu5Zn8 alloy phases in the film were directly controlled by the concentration of Cu(II). SEM measurements have shown that Sn(II) has significant impact on film morphology, which became more porous as a result of the larger nucleation size of tin. The changes in the surface properties of the films was also confirmed by chronoamperometry characteristic (i–t) deposition curves. By optimization of metal ion concentrations in the electrolyte solution, a copper-poor and zinc-rich kesterite Cu2ZnSnS4 (CZTS) film was synthesized by the sulfurization of the deposited CZT film. The solar cell with the CZTS film showed an energy conversion efficiency of 2.15% under the illumination intensity of 100 mW cm 2.

Nanostructured hydroxyapatite surfaces-mediated adsorption alters recognition of BMP receptor IA and bioactivity of bone morphogenetic protein-2

Highly efficient loading of bone morphogenetic protein-2 (BMP-2) onto carriers with desirable performance is still a major challenge in the field of bone regeneration. Till now, the nanoscaled surface-induced changes of the structure and bioactivity of BMP-2 remains poorly understood. Here, the effect of nanoscaled surface on the adsorption and bioactivity of BMP-2 was investigated with a series of hydroxyapatite surfaces (HAPs): HAP crystal-coated surface (HAP), HAP crystal-coated polished surface (HAP-Pol), and sintered HAP crystal-coated surface (HAP-Sin). The adsorption dynamics of recombinant human BMP-2 (rhBMP-2) and the accessibility of the binding epitopes of adsorbed rhBMP-2 for BMP receptors (BMPRs) were examined by a quartz crystal microbalance with dissipation. Moreover, the bioactivity of adsorbed rhBMP-2 and the BMP-induced Smad signaling were investigated with C2C12 model cells. A noticeably high mass-uptake of rhBMP-2 and enhanced recognition of BMPR-IA to adsorbed rhBMP-2 were found on the HAP-Pol surface. For the rhBMP-2-adsorbed HAPs, both ALP activity and Smad signaling increased in the order of HAP-Sin < HAP < HAP-Pol. Furthermore, hybrid molecular dynamics and steered molecular dynamics simulations validated that BMP-2 tightly anchored on the HAP-Pol surface with a relative loosened conformation, but the HAP-Sin surface induced a compact conformation of BMP-2. In conclusion, the nanostructured HAPs can modulate the way of adsorption of rhBMP-2, and thus the recognition of BMPR-IA and the bioactivity of rhBMP-2. These findings can provide insightful suggestions for the future design and fabrication of rhBMP-2-based scaffolds/implants.

Visible light enhanced oxidant free dehydrogenation of aromatic alcohols using Au-Pd alloy nanoparticle catalysts

We find that visible light irradiation of gold–palladium alloy nanoparticles supported on photocatalytically inert ZrO2 significantly enhances their catalytic activity for oxidant-free dehydrogenation of aromatic alcohols to the corresponding aldehydes at ambient temperatures. Dehydrogenation is also the dominant process in the selective oxidation of the alcohols to the corresponding aldehydes with molecular oxygen. The alloy nanoparticles strongly absorb light and exhibit superior catalytic and photocatalytic activity when compared to either pure palladium or gold nanoparticles. Analysis with a free electron gas model for the bulk alloy structure reveals that the alloying increases the surface charge heterogeneity on the alloy particle surface, which enhances the interaction between the alcohol molecules and the metal NPs. The increased surface charge heterogeneity of the alloy particles is confirmed with density function theory applied to small alloy clusters. Optimal catalytic activity was observed with a Au : Pd molar ratio of 1 : 186, which is in good agreement with the theoretical analysis. The rate-determining step of the dehydrogenation is hydrogen abstraction. The conduction electrons of the nanoparticles are photo-excited by the incident light giving them the necessary energy to be injected into the adsorbed alcohol molecules, promoting the hydrogen abstraction. The strong chemical adsorption of alcohol molecules facilitates this electron transfer. The results show that the alloy nanoparticles efficiently couple thermal and photonic energy sources to drive the dehydrogenation. These findings provide useful insight into the design of catalysts that utilize light for various organic syntheses at ambient temperatures.