Designing catalytic nanomotors by dynamic shadowing growth

Using a geometric shadowing effect, a thin catalyst layer can be coated asymmetrically on the side of a nanorod backbone. Combining with substrate rotation, a dynamic shadowing growth technique has been developed to fabricate catalytic nanomotors such as rotary Si/Pt nanorods, rotary L-shaped Si/Pt and Si/Ag nanorods, and rolling Si/Ag nanosprings, and their autonomous motions have been demonstrated in a diluted H2O2 solution. This fabrication method reveals an optimistic step toward designing integrated nanomachines.     

Geometrically designing the kinematic behavior of catalytic nanomotors

Catalytic nanomotors with silica microbead heads and TiO(2) arms are systematically designed by dynamic shadowing growth. The swimming trajectories are fine tuned by altering the arm length and orientation exploiting geometry-dependent hydrodynamic interactions at low Reynolds number. The curvature, angular frequency, and radius of curvature of the trajectories change as a function of arm length. Simulations based on the method of regularized Stokeslets are also described and correctly capture the trends observed in the experiments.     

Near-infrared light-driven yolk@shell carbon@silica nanomotors for fuel-free triglyceride degradation

Yolk@shell mesoporous nanoparticles have received close attention due to their controllable structures and integrated functions.However,most yolk@shell nanosystems lack self-propulsion.Herein,yolk@spiky-shell structured carbon@silica nanomotors are fabricated with near-infrared(NIR)light self-thermophoretic propulsion as lipase nanocarriers for fuel-free triglyceride degradation.The light propulsion accelerates the accumulation of nanomotors on the droplet interface,and the efficient lipase loading further facilitates the rapid degradation of tributyrin droplets.By adjusting the yolk and spiky structure,the obtained semi-yolk@spiky-shell structured nanomotors exhibit the highest capacity of lipase(442 mg/g)and the highest light-driven diffusion coefficient(ca.55%increase under 2 W/cm^(2 )irradiation),thus improving the degradation efficiency of triglyceride(93.1%under NIR light vs.66.7%without NIR light within 20 min).This work paves the way to rationally design yolk@shell structured nanomotors for diverse applications.     

AMACE1: versatile aminoacetamide electrophore reagent

Acetamide, 2-amino-N-[[3,5-bis(trifluoromethyl)phenyl]-methyl]-N-methyl-, monohydrochloride, which we have named AMACE1, was synthesized in three steps starting from N-tritylglycine. AMACE1 was coupled via its primary amine group (pKa 8.2) under aqueous conditions to four model analytes for oxidative sugar damage to DNA: glycolate, 3-hydroxy-2-butanone, 3-phenylbutyraldehyde, and alpha-hydroxy-gamma-butyrolactone, relying on cyanoborohydride for coupling to a keto function and a water-soluble carbodiimide for coupling to a carboxyl function. Further reaction with butyric anhydride led to products that could be detected by gas chromatography/electron capture mass spectrometry when 1 microL of ethyl acetate containing essentially 20 amol of each product was injected, on the basis of selected ion monitoring of the analyte characteristic anion fragment from dissociative loss of the 3,5-bis-(trifluoromethyl)phenylmethyl moiety: m/z 215, 289, 299, and 329, respectively. Since many small, organic analytes contain a keto or carboxylic acid group, AMACE1 should be useful in general in the area of trace organic analysis.     

The PTB microbeam: a versatile instrument for radiobiological research

The PTB microbeam is routinely used for the irradiation of living cells using protons (1-20 MeV) and alpha particles (1-28 MeV). The beam diameter is approximately 2 microm (fwhm), achieved by focussing, resulting in an excellent energy resolution and practically no scattered particles. Recently, an electrostatic beam scanner was added to the facility which allows targeting of each cell within 1 ms. This and other improvements led to an increase in the experimental speed of the system to a maximum of 50,000 cells per hour including all experimental steps. To improve the versatility of the facility further, a module for automatic quantification of immunocytochemical staining was implemented. This allows the analysis of protein activation, taking into account the positional information of the irradiation run.     

A versatile optical alignment tool

An optical alignment tool is described, which acts like an optical tee to produce two collinear beams whose direction can be adjusted. The device can be used to align optica subsystems.     

Stochastic analysis of versatile workcentres

We analyse the system consisting of a highly capable workcentre, which processes a variety of part types, using queueing models. The various part types produced by the system have distinct arrival and processing durations that are stochastic in nature. When an arriving workpiece finds the machine busy, it waits in a pre-process storage buffer (queue); this buffer may be common for all the part types, or may be dedicated for that part type. Further, this buffer may be capable of holding only a finite number of workpieces, or may be of infinite capacity. When the machine changes over from producing one type of part to another, a setup operation of stochastic duration is necessary to adjust the machine and load the necessary tools for production of the next part type. This model is representative of a typical machining centre in an Automated Manufacturing System. We focus ongi/g/1 models and multiqueue polling models, and their variants. The important performance measures of the system obtained by queueing analysis are the part-type-wise values of the mean lead time, mean inventory level, and the mean machine utilisation.     

Rigidly connected overlapping spherical particles: a versatile grain model

This paper describes a method to simulate the dynamics of granular systems consisting of irregularly shaped grains. This method is a simplification and partial improvement of a method that has been developed and employed earlier in simulating the toning process in electro-photographic copiers. Here, grains are modeled as rigidly connected overlapping spherical particles. For each grain a bounding sphere around the center-of-mass is known. Therefore, it can efficiently be decided whether two particles intersect and thus exert contact forces upon each other. A second order time stepping algorithm for such grains is given which needs only one evaluation of the interparticle forces in a time step. In a ten grain example system a favorable but poorly understood phenomenon of energy restoration is exemplified.U. Mutze retired from R&D for a subsidiary of Heidelberger Druckmaschinen AG, after R&D work for a subsidiary of Eastman Kodak Company.     

Water soluble cellulose acetate: a versatile polymer for film coating

The objective of this study was to investigate the use of water soluble cellulose acetate (WSCA) as a film coating material for tablets. Aspirin (ASA) tablets were prepared by direct compression and coated with either WSCA or HPMC (hydroxypropyl methylcellulose) dispersions. Coatings of 1-3%, depending on the intended application, were applied to the model drug (ASA) tablets employing a side-vented coating pan. Free films of WSCA, prepared by cast method, are crystal clear and, depending on the viscosity grade, are flexible, strong and durable. WSCA has the capability of forming free films without plasticizers and the films dry at room temperature. Glass transition temperature, Tg, was determined by differential scanning calorimetry. The Tg of WSCA is significantly higher relative to HPMC. Inclusion of plasticizer lowers the Tg of WSCA and effective plasticizers were PEG 400 and glycerin. Low viscosity WSCA was more soluble in water (25-30%) relative to medium viscosity WSCA (10-15%). WSCA solutions exhibited no increase in viscosity with an increase in temperature. Samples of coated (WSCA and HPMC) tablets and uncoated ASA cores were packaged for stability studies at room and elevated temperature storage. Physical stability of ASA tablets coated with 2:1 LV: MV (low viscosity: medium viscosity) WSCA formulations was better when compared to tablets coated with HPMC. Dissolution stability of WSCA coated ASA was similar to the physical stability results. After three months at elevated temperature (35 and 45°C), the WSCA coated tablets complied with USP dissolution requirements for ASA, while the HPMC coated tablets did not. There was no difference in moisture (weight) gain of ASA tablets coated with either WSCA or HPMC. The WSCA coated tablets were not sticky or tacky, while the HPMC coated tablets were tacky and stuck together.     

Polysodium N-undecanoyl-L-leucylvalinate: a versatile chiral selector for micellar electrokinetic chromatography

Dipeptide micelle polymers are a new class of polymeric surfactants of which the polysodium undecanoyl-L-leucylvalinate (poly-L-SULV) was found to be a broadly applicable chiral selector for micellar electrokinetic chromatography. This negatively charged dipeptide micelle polymer is a high molecular weight compound with large countercurrent mobility, zero critical micelle concentration, low aggregation number, and high solubility in water or water-organic solvents. In an extensive chiral screening program, enantioseparation of 75 racemic compounds was tested with poly-L-SULV as chiral pseudostationary phase in neutral pH and basic pH background electrolytes. A total of 58 out of 75 racemic compounds could be resolved after choosing an appropriate concentration of poly-L-SULV. Although anionic chiral analytes are difficult to resolve using poly-L-SULV, the percent success rate for chiral resolution of cationic (77%) and neutral (85%) racemates was very high. Aspects regarding electrostatic, steric, hydrophobic, and hydrogen-bonding interactions of this dipeptide micelle polymer with various classes of chiral analytes are discussed.     

Sol-gel processing: A versatile concept for special glasses and ceramics

The various parameters related to sol-gel processing are discussed with special reference to those which usually attract less attention but depending on the final product in mind, can play important roles. The versatility of the sol-gel technique in materials preparation is demonstrated by discussing the various products developed at the author’s laboratory by using this processing method.     

Ultrastable MOF-based foams for versatile applications

Metal-organic frameworks(MOFs)are attractive for promising applications but plagued by difficult recovery and deployment due to their intrinsic nano/micro powde...     

Magnetically triggered nanocomposite membranes: a versatile platform for triggered drug release

Drug delivery devices based on nanocomposite membranes containing thermoresponsive nanogels and superparamagnetic nanoparticles have been demonstrated to provide reversible, on-off drug release upon application (and removal) of an oscillating magnetic field. We show that the dose of drug delivered across the membrane can be tuned by engineering the phase transition temperature of the nanogel, the loading density of nanogels in the membrane, and the membrane thickness, allowing for on-state delivery of model drugs over at least 2 orders of magnitude (0.1-10 μg/h). The zero-order kinetics of drug release across the membranes permit drug doses from a specific device to be tuned according to the duration of the magnetic field. Drugs over a broad range of molecular weights (500-40000 Da) can be delivered by the same membrane device. Membrane-to-membrane and cycle-to-cycle reproducibility is demonstrated, suggesting the general utility of these membranes for drug delivery.     

Self-powered versatile shoes based on hybrid nanogenerators

A triboelectric nanogenerator (TENG) and an electromagnetic generator (EMG) were hybridized to harvest the human mechanical energy. By an effective conjunction of triboelectrification and electromagnetic induction, the hybridized nanogenerator with a radius of 2 cm and height of 1.2 cm could charge a 1,000 μF capacitor to 5.09 V after 100 cycles of vibration. This mini-sized hybrid nanogenerator could then be embedded in shoes to serve as an energy cell. Typical outdoor applications—including driving with a Global Positioning System (GPS) device, charging a Li-ion battery and a cell phone—were successfully demonstrated, suggesting its potential application in smart wearable electronics and future suits of soldiers.

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New versatile polydopamine coated functionalized magnetic nanoparticles

Polydopamine coated magnetite nanoparticles are functionalized with azido groups by reaction with 4-azidobutylamine. The resulting nanoparticles allow straight forward Cu-catalyzed “click”-reaction with alkynes. In this way practically interesting functions can be tethered to the nanoparticles as exemplified by introducing biotin, glucose, proline or dansyl. The nanoparticles exhibit superparamagnetic behavior.     

Metal@Silica yolk-shell nanostructures as versatile bifunctional nanocatalysts

Recent developments in nanochemistry offer precise morphology control of nanomaterials, which has significant impacts in the field of heterogeneous catalysis. Rational design of bifunctional catalysts can influence various aspects of catalytic properties. In this review, a new class of bifunctional catalysts with a metal@silica yolk-shell nanostructure is introduced. This structure has many advantages as a heterogeneous catalyst since it ensures a homogeneous environment around each metal core, and particle sintering is effectively eliminated during high temperature reactions. The catalysts exhibit high activity and recyclability in gas- and solution-phase reactions. It is anticipated that appropriate selection of bifunctional components and optimal structural control will significantly further enhance the catalytic properties, and enable target reaction-oriented development of new catalysts.     

A versatile multi-platform biochip surface attachment chemistry

A versatile DNA spotting and immobilization method for covalent attachment of amino-modified probe oligonucleotides in microarray format at glass, native silicon dioxide and CVD silicon nitride substrates is reported. Optimal probe spot printing and attachment buffers are identified for each substrate. Relative areal densities of immobilized probes as measured by epi-fluorescence microscopy vary with substrate type reflecting differences in surface morphology and chemistry. Target oligonucleotide hybridization occurs at glass and nitride supported probe microarrays in an efficient and reproducible manner with excellent measured fluorescence signal-to-background.     

Trident: a versatile high-power Nd:glass laser facility for inertial confinement fusion experiments

The Trident Nd:glass laser system operates as an experimental facility supporting the national Inertial Confinement Fusion program at Los Alamos. The laser has two identical main beam lines with 14-cm-disk final amplifiers. The beams are frequency doubled, expanded to 19.2 cm, and focused on target with a variety of focusing optics. A third beam with 10-cm disk final amplifiers is also frequency doubled and used as a target-shooting or diagnostic beam simultaneously with the other two beams.

The facility provides a flexible combination of energy, pulse-shaping capabilities, and diagnostic tools for laser-target interaction experiments.