A TiO2‐Binding Protein isolated from Rhodococcus Strain GIN‐1 (NCIMB 40340) – Purification,Properties and Potential Applications

A Rhodocuccus strain (Rh. GIN1, NCIMB 40340), which is capable of adsorption to titanium dioxide (TiO₂) and TiO₂‐containing coal fly ash particles, has been isolated previously in our Lab. Selectivity experiments showed that the bacterium is capable of adsorption to other metal oxides as well (e.g. magnetite and Al₂O₃) but at lower affinities. The bacterium binds tightly both to rutile and anatase TiO₂. In electronmicrograms the formation of “bridge‐like” structures between the bacterium and the oxide is observed. A specific protein fraction, located on the cell wall of the bacterium was isolated from the bacterium. This protein was found to adhere strongly to TiO₂ particles at high salt concentrations, similarly to the binding to TiO₂ of the intact bacteria. TiO₂ (rutile) was found to bind the protein faster, stronger and at a higher capacity than the anatase isoform. The 55 kDa Ti‐Binding Protein (TiBP) was isolated from the bacteria after homogenization by French Press. It was purified by affinity chromatography on TiO₂ particles, hydrophobic chromatography on a Fractogel‐propyl column and gel filtration on a Superdex G‐200 column. The same protein was isolated from the bacteria by treatment with mutanolysin, an enzyme which is commonly used to retrieve cell‐wall proteins from Gram‐positive bacteria, demonstrating the outer cell location of the protein in Rh. GIN1. TiBP exhibits metal oxide binding selectivity similar to that of the intact bacterium, namely TiO₂>ZnO>Al₂O₃ >Fe₂O₃(magnetite). Hydrophobic forces seem to dominate the interactions of the protein with TiO₂ as its binding capability is greatly enhanced in the presence of high concentrations of NaCl and its desorption requires high concentrations of urea and SDS. These features differentiate TiBP from other proteins known to adsorb TiO₂ (such as hemoglobin, cytochrome c and bovine serum albumin), mainly by weak, charge‐based interactions.     

Rule induction in the discrimination of virulent and avirulent isolates of the plant bacterium Erwinia amylovora,from fatty acid profiles

Virulent isolates of the bacterium Erwinia amylovora cause fire blight, a serious disease of Rosaceous plants. Metabolic profiles of whole-cell fatty acid methyl esters (FAME) were obtained from a “training” set of 43 isolates with known virulence reactions. Rule induction was used to generate a decision tree relating the FAME profile composition to the virulence reaction of these isolates. The decision-tree was used to predict the virulence reactions for a “test” set of 16 isolates, later subjected to biological testing. The marked success of these procedures showed that reliable predictions of virulence can be achieved for isolates within a single species. The first evidence for host-specificity within E. amylovora was obtained and markers for Pseudomonas bacteria were identified. This approach to the discrimination of virulence may be applicable to human and animal pathogens.     

Advanced Hybrid GaN/ZnO Nanoarchitectured Microtubes for Fluorescent Micromotors Driven by UV Light

The development of functional microstructures with designed hierarchical and complex morphologies and large free active surfaces offers new potential for improvement of the pristine microstructures properties by the synergistic combination of microscopic as well as nanoscopic effects. In this contribution, dedicated methods of transmission electron microscopy (TEM) including tomography are used to characterize the complex hierarchically structured hybrid GaN/ZnO:Au microtubes containing a dense nanowire network on their interior. The presence of an epitaxially stabilized and chemically extremely stable ultrathin layer of ZnO on the inner wall of the produced GaN microtubes is evidenced. Gold nanoparticles initially trigger the catalytic growth of solid solution phase (Ga_1–xZn_x)(N_1–xO_x) nanowires into the interior space of the microtube, which are found to be terminated by AuGa‐alloy nanodots coated in a shell of amorphous GaO_x species after the hydride vapor phase epitaxy process. The structural characterization suggests that this hierarchical design of GaN/ZnO microtubes could offer the potential to exhibit improved photocatalytic properties, which are initially demonstrated under UV light irradiation. As a proof of concept, the produced microtubes are used as photocatalytic micromotors in the presence of hydrogen peroxide solution with luminescent properties, which are appealing for future environmental applications and active matter fundamental studies.     

Chemical Nanomotors at the Gram Scale Form a Dense Active Optorheological Medium

The rheological properties of a colloidal suspension are a function of the concentration of the colloids and their interactions. While suspensions of passive colloids are well studied and have been shown to form crystals, gels, and glasses, examples of energy‐consuming “active” colloidal suspensions are still largely unexplored. Active suspensions of biological matter, such as motile bacteria or dense mixtures of active actin–motor–protein mixtures have, respectively, reveals superfluid‐like and gel‐like states. Attractive inanimate systems for active matter are chemically self‐propelled particles. It has so far been challenging to use these swimming particles at high enough densities to affect the bulk material properties of the suspension. Here, it is shown that light‐triggered asymmetric titanium dioxide that self‐propel, can be obtained in large quantities, and self‐organize to make a gram‐scale active medium. The suspension shows an activity‐dependent tenfold reversible change in its bulk viscosity.     

EBSD Study of Microstructural Evolution in a Nickel‐Base Superalloy during Two‐Pass Hot Compressive Deformation

Generally, the high‐temperature deformation characteristics and microstructural evolution of alloys are studied by isothermal compressive experiments at stable strain rates. But, the strain rate is variant during the practice industrial production of components. In this work, isothermal two‐pass hot compression experiments with stepped strain rates are performed to analyze the microstructural evolution of a nickel‐base superalloy with δ phase. Results reveal that the mean grain size decreases, but the percentage of undissolved δ phases increases, as the strain rate of the first pass (SROFP) is increased. However, the mean grain size and the percentage of undissolved δ phases decreases with the increase of inter‐pass time (IPT) or the true strain of the first pass (TSOFP). Meanwhile, the increased deformation temperature easily enlarges the mean grain size, but obviously decreases the percentage of undissolved δ phases. In addition, the evolution of Σ3ⁿ boundaries not only results from the “new twinning mechanism”, but also “Σ3ⁿ regeneration mechanism”. “Σ3ⁿ regeneration mechanism” becomes predominant with decreasing SROFP or increasing IPT/TSOFP. Besides, “new twinning mechanism” plays a major role on Σ3ⁿ boundaries evolution as the temperature is increased from 950 to 980 °C, and then become weaken with further increasing the deformation temperature.

     

Three-primary-color upconversion luminescence in rare earth-doped <Emphasis Type="Italic">β</Emphasis>-NaLuF<Subscript>4</Subscript> microtubes

Lanthanide ions-doped NaLuF₄ hexagonal-prismatic microtubes have been successfully synthesized via a facile hydrothermal approach for the first time. The as-grown microtubes are determined to be pure hexagonal (β-) NaLuF₄ phase with an outermost diameter of about 3 μm and a length of approximately 40 μm. The Yb³⁺/Er³⁺(Tm³⁺)-codoped NaLuF₄ microtubes emit bright three-primary-color (red, green, and blue) light under 980 nm laser diode excitation undergoing an upconversion. Mechanisms for the excitation and emission were analyzed based on the emission spectra, the plot of luminescence intensity to pump power and a simplified energy level diagram.     

Ti3C2TX MXene Ink Direct Writing Flexible Sensors for Disposable Paper Toys

Flexible electronics have gained great attention in recent years owing to their promising applications in biomedicine, sustainable energy, human-machine interaction, and toys for children. Paper mainly produced from cellulose fibers is attractive substrate for flexible electronics because it is biodegradable, foldable, tailorable, and light-weight. Inspired by daily handwriting, the rapid prototyping of sensing devices with arbitrary patterns can be achieved by directly drawing conductive inks on flat or curved paper surfaces; this provides huge freedom for children to design and integrate “do-it-yourself (DIY)” electronic toys. Herein, viscous and additive-free ink made from Ti₃C₂T_X MXene sediment is employed to prepare disposable paper electronics through a simple ball pen drawing. The as-drawn paper sensors possess hierarchical microstructures with interweaving nanosheets, nanoflakes, and nanoparticles, therefore exhibiting superior mechanosensing performances to those based on single/fewer-layer MXene nanosheets. As proof-of-concept applications, several popular children's games are implemented by the MXene-based paper sensors, including “You say, I guess,” “Emotional expression,” “Rock-Paper-Scissors,” “Arm wrestling,” “Throwing game,” “Carrot squat,” and “Grab the cup,” as well as a DIY smart whisker for a cartoon mouse. Moreover, MXene-based paper sensors are safe and disposable, free from producing any e-waste and hazard to the environment.     

Molecular Switch Controlled by Pulsed Bias Voltages

Recent experiments have shown that the current–voltage characteristics (I–V) of BPDN‐DT (bipyridyl‐dinitro oligophenylene‐ethynylene dithiol) can be switched in a very controlled manner between “on” and “off” traces by applying a pulse in a bias voltage, V_bias. Here, the polaron formation energies are calculated to check a frequently held belief, namely, that the polaron formation can explain the observed bistability. These results are not consistent with such a mechanism. Instead, a conformational reorientation is proposed. The molecule carries an intrinsic dipole moment, which couples to V_bias. Ramping V_bias exerts a force on the dipole that can reorient (“rotate”) the molecule from the ground state (“off”) into a metastable configuration (“on”) and back. By elaborated electronic structure calculations, a specific path for this rotation is identified through the molecule's conformational phase space. It is shown that this path has sufficiently high barriers to inhibit thermal instability but that the molecule can still be switched in the voltage range of the junction stability. The theoretical I–Vs qualitatively reproduce the key experimental observations. A proposal for the experimental verification of the alternative mechanism of conductance switching is presented.     

Biocompatibility of Dental Alloys

Modern dental alloys have been used for 50 years to produce prosthetic dental restorations. Generally, the crowns and frames of a prosthesis are prepared in dental alloys, and then veneered by feldspar ceramics or composites. In use, the alloys are exposed to the corrosive influence of saliva and bacteria. Metallic dental materials can be classified as precious and non‐precious alloys. Precious alloys consist of gold, platinum, and small amounts of non‐precious components such as copper, tin, or zinc. The non‐precious alloys are based on either nickel or cobalt, alloyed with chrome, molybdenum, manganese, etc. Titanium is used as Grade 2 quality for dental purposes. As well as the dental casting alloys, high purity electroplated gold (99.8 wt.‐%) is used in dental technology. This review discusses the corrosion behavior of metallic dental materials with saliva in “in vitro” tests and the influence of alloy components on bacteria (Lactobacillus casei and Streptococcus mutans). The test results show that alloys with high gold content, cobalt‐based alloys, titanium, and electroplated gold are suitable for use as dental materials.     

Relationship Between System Failure Rate and Component Failure Rates

A simple sufficient condition is given for a system to have an increasing failure rate when the identical components comprising it have an increasing failure rate. Systems which function if and only if at least k of the n components function (“k out of n” systems) satisfy this condition. For systems of non-identical components, upper and lower bounds on failure rate are obtained in terms of component failure rates. These bounds are increasing functions of time for “k out of n” structures having components with increasing failure rates.     

Biofunctionalised quantum dots for sensing and identification of waterborne bacterial pathogens

Harmful bacteria are the most common cause of food- and waterborne illnesses. Infection often leads to bloody diarrhoea, and occasionally to kidney failure. Several strains of the bacteria Escherichia coli produce a powerful toxin which causes serious illness. Food and water can be contaminated with other bacteria like Salmonella, Coliform, Pseudomonas, etc. Hence, it has become important to rapidly detect and identify infectious bacteria. Colloidal luminescent semiconductor nanocrystals or quantum dots (QDs) have elicited a great deal of interest in the biosensing community due to their unique fluorescent properties. Here ZnS?:?Mn²⁺ QDs are synthesised and biofunctionalised with chitosan. They are attached to the anionic cell wall of E. coli bacteria and different properties of this compound system are studied. These nanocrystals may offer cost effective and quicker alternative to detect single bacterium compared to other conventional methods. The process of the synthesis of QDs, biofunctionalisation and detection of bacteria have been characterised by XRD, UV-Vis spectroscopy, FTIR, photoluminescence spectroscopy, AFM, high-resolution transmission electron microscopy and confocal microscopy. The particle size calculated is approximately 8–10?nm. The blue shift of PL peak has been observed after the bacteria get attached.     

Formation of transition-metal sulfide microspheres or microtubes

Cu_xS (x = 1, 2) microtubes, and a series of transition-metal sulfide (CdS, ZnS, NiS, CoS, CuS and Cu₂S) compounds microspheres were successfully synthesized through a facile hydrothermal reaction. These compounds have been characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The optical properties of ZnS and CdS have also been investigated by UV–vis absorption and fluorescence spectroscopy. The possible formation mechanism of these microspheres or microtubes was discussed based on the experimental results.     

Moulded pulp products manufacturing with thermoforming

For an effective optimization of pulp thermoforming and of the moulded pulp products manufactured by this process, a full understanding of the process physics combined with full knowledge of the pressing equipment is necessary. For this reason, in this Addendum, we clarify how the process parameters “Holding time,” “Vacuum time,” “Cycle time,” and “Temperature” were interpreted and subsequently defined for the analysis of the process and product‐related outputs of the thermoforming experiments.     

Brass Rings or Brass Buttons in Engineering Design*

The purpose of this paper is to point out two distinct selections for student design projects. The main decision maker is assumed to be the faculty advisor for the projects, although the students would be expected to have input. The brass ring project involves some aspect of cutting edge technology. The brass button project is one that satisfies the typical criteria of a thoroughly designed, fabricated, and documented “component.” Both types of projects have great value for the students although one is obviously more visible outside the academic community. These two philosophical approaches in engineering design projects reflect the distinction between entrepreneurial and traditional engineering education. As we move from the concept of engineers working for large companies to engineers starting companies, this distinction becomes more important. The primary example base is drawn from electrical and mechanical engineering due to our experiences. While two philosophical approaches are indicated, there are ultimately numerous methodologies and end points possible as a result of diversions along the way.     

Generalized Bose–Einstein Condensation

Generalized Bose–Einstein condensation (GBEC) involves condensates appearing simultaneously in multiple states. We review examples of the three types in an ideal Bose gas with different geometries. In Type I there is a discrete number of quantum states each having macroscopic occupation; Type II has condensation into a continuous band of states, with each state having macroscopic occupation; in Type?III each state is microscopically occupied while the entire condensate band is macroscopically occupied. We begin by discussing Type I or “normal” BEC into a single state for an isotropic harmonic oscillator potential. Other geometries and external potentials are then considered: the “channel” potential (harmonic in one dimension and hard-wall in the other), which displays Type II, the “cigar trap” (anisotropic harmonic potential), and the “Casimir prism” (an elongated box), the latter two having Type III condensations. General box geometries are considered in an appendix. We particularly focus on the cigar trap, which Van Druten and Ketterle first showed had a two-step condensation: a GBEC into a band of states at a temperature T _c and another “one-dimensional” transition at a lower temperature T ₁ into the ground state. In a thermodynamic limit in which the ratio of the dimensions of the anisotropic harmonic trap is kept fixed, T ₁ merges with the upper transition, which then becomes a normal BEC. However, in the thermodynamic limit of Beau and Zagrebnov, in which the ratio of the boundary lengths increases exponentially, T ₁ becomes fixed at the temperature of a true Type I phase transition. The effects of interactions on GBEC are discussed and we show that there is evidence that Type III condensation may have been observed in the cigar trap.     

Addition of “Living” Polymers onto C60.

Abstract

Various “living” polymers were grafted onto C₆₀ The number of arms of the so obtained “star” molecules can be controlled by stoechiometry and/or by varying the reactivity of the carbanion on the “living” chain against a double bond on the C₆₀. Even the oxanion of “living” polyethylenoxide is able to add onto the reactive double bonds on C₆₀. In some conditions, the carbanions present on these alkaline salts of grafted fullerenes becomes able to initiate anionic polymerization of vinyl monomers. Using “living” poly(phenylvinylsulfoxide) as a precursor polymer for PA, polyacetylene chains could be attached to the fullerene.     

Biosynthesis and Characterization of Copper Nanoparticles Using Shewanella oneidensis: Application for Click Chemistry

Copper nanoparticles (Cu‐NPs) have a wide range of applications as heterogeneous catalysts. In this study, a novel green biosynthesis route for producing Cu‐NPs using the metal‐reducing bacterium, Shewanella oneidensis is demonstrated. Thin section transmission electron microscopy shows that the Cu‐NPs are predominantly intracellular and present in a typical size range of 20–40 nm. Serial block‐face scanning electron microscopy demonstrates the Cu‐NPs are well‐dispersed across the 3D structure of the cells. X‐ray absorption near‐edge spectroscopy and extended X‐ray absorption fine‐structure spectroscopy analysis show the nanoparticles are Cu(0), however, atomic resolution images and electron energy loss spectroscopy suggest partial oxidation of the surface layer to Cu₂O upon exposure to air. The catalytic activity of the Cu‐NPs is demonstrated in an archetypal “click chemistry” reaction, generating good yields during azide‐alkyne cycloadditions, most likely catalyzed by the Cu(I) surface layer of the nanoparticles. Furthermore, cytochrome deletion mutants suggest a novel metal reduction system is involved in enzymatic Cu(II) reduction and Cu‐NP synthesis, which is not dependent on the Mtr pathway commonly used to reduce other high oxidation state metals in this bacterium. This work demonstrates a novel, simple, green biosynthesis method for producing efficient copper nanoparticle catalysts.     

The Floating Face: Garbo,Photography and Death Masks

A number of writers have noted the influence of Ernst Benkard’s 1927 book of death masks, Das Ewige Antlitz, on Modernist artists and writers of the inter-war period. This article links it specifically to the emergence in the late 1920s of a very particular way of photographing people, termed here “the floating face”, which is epitomised in publicity portraits of Greta Garbo. It is suggested that this photographic convention is linked to changing attitudes associated with war, to the techniques of cinema, and to surrealism, but also to the influence of Benkard’s book. The resemblance between the death mask image and movie star portrait is significant for an understanding of the origins and affective impact of a certain photographic style. This essay also suggests that the death mask as a figure in film and photography theory emerges out of this particular style of photography, and this specific social and cultural context, but then becomes applied to “the photograph” in general. It is argued that the idea of photographs as like death masks is overdetermined by the social and cultural context of 1920s Europe.     

Ecologically Driven Ultrastructural and Hydrodynamic Designs in Stomatopod Cuticles

Ecological pressures and varied feeding behaviors in a multitude of organisms have necessitated the drive for adaptation. One such change is seen in the feeding appendages of stomatopods, a group of highly predatory marine crustaceans. Stomatopods include “spearers,” who ambush and snare soft bodied prey, and “smashers,” who bludgeon hard‐shelled prey with a heavily mineralized club. The regional substructural complexity of the stomatopod dactyl club from the smashing predator Odontodactylus scyllarus represents a model system in the study of impact tolerant biominerals. The club consists of a highly mineralized impact region, a characteristic Bouligand architecture (common to arthropods), and a unique section of the club, the striated region, composed of highly aligned sheets of mineralized fibers. Detailed ultrastructural investigations of the striated region within O. scyllarus and a related species of spearing stomatopod, Lysiosquillina maculate show consistent organization of mineral and organic, but distinct differences in macro‐scale architecture. Evidence is provided for the function and substructural exaptation of the striated region, which facilitated redeployment of a raptorial feeding appendage as a biological hammer. Moreover, given the need to accelerate underwater and “grab” or “smash” their prey, the spearer and smasher appendages are specifically designed with a significantly reduced drag force.