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The combination of hazard evaluation and risk analysis is an organized effort to pinpoint weaknesses in the design and operation of facilities that could lead to accidental or unintentional chemical releases, fires or explosions. These studies assist organizations with the goal of improving safety and managing the risk of operations. However, reported data on incidents in academic chemistry laboratories indicates that the accident rate is 10–50 times higher than that in industrial laboratories. These data suggest that risk reduction efforts in academic laboratories are less successful than those practiced by the chemical industry. Investigation findings of accidents in academic laboratories often point to the absence of a risk analysis of the synthesis that led to the accident. This paper discusses the relationship between the hazards and consequences of an upset event, the likelihood of the upset happening, and the resulting risk to personnel, property and the environment. Some well-established risk procedures have been adapted to the task of hazard identification and risk assessment in the chemical research laboratory. These risk studies are preceded by a Chemical Hazard Review that is used to identify those aspects of a chemical synthesis that could have a hazardous outcome if there is an upset or a deviation from the desired synthesis procedure. A powerful advantage of this approach is that it encourages and enables a research laboratory group to consider less obvious ways in which an upset may occur, even though it may seem unlikely at first consideration. The risk assessment becomes much more than a mechanistic check-list type of review making it more likely that potential failures and problems, not previously encountered with this activity, will be identified.

A review of 27 Chemical Hygiene plans and safety manuals used in university chemistry labs, and posted on the Internet, suggests that the use of hazard identification and risk analysis procedures in academia is an infrequent practice. This, unfortunately, is the genesis of accidents. However, a goal of zero incidents and accidents in the laboratory is desired, and it can be achieved with systematic hazard identification and risk analyses procedures. This article describes a three part process to assess the risks of any work that involves chemical reactions in the research laboratory. The first step identifies the hazard potentials of a chemical synthesis study. This hazards' review helps researchers to fully appreciate the nature and extent of the potential hazards of the planned synthesis study. The second step involves conducting a formal risk analysis, and the third step develops and implements risk minimization measures. This described process is used to lower accident rates by helping researchers understand the hazards and to implement hazard minimization controls and conditions before starting chemical synthesis studies. © 2012 American Institute of Chemical Engineers Process Saf Prog, 2012

Using scanning near-field lithography (SNP), it is possible to pattern molecules at surfaces with a resolution as good as 9 nm [M. Montague, R. E. Ducker, K. S. L. Chong, R. J. Manning, F. J. M. Rutten, M. C. Davies and G. J. Leggett, Langmuir 23 (13), 7328–7337 (2007)]. However, in common with other scanning probe techniques, SNP has previously been considered a serial process, hindering its use in many applications. IBM’s “Millipede” addresses this problem by utilizing an array of local probes operating in parallel. Here, we describe the construction of two instruments (Snomipedes) that integrate near-field optical methods into the parallel probe paradigm and promise the integration of top–down and bottom–up fabrication methods over macroscopic areas. Both are capable of performing near-field lithography with 16 probes in parallel spanning approximately 2 mm. The instruments can work in both ambient and liquid environments, key to many applications in nanobiology. In both, separate control of writing is possible for each probe. We demonstrate the deprotection of self-assembled monolayers of alkylsilanes with photocleavable protecting groups and subsequent growth of nanostructured polymer brushes from these nanopatterned surfaces by atom-transfer radical polymerization.

Scanning near-field photolithography (SNPL) has recently shown its great potential for fabricating various structures at the nanoscale. However, the low throughput of SNPL is a barrier to wider applications. Additionally, to extend SNPL to operation in aqueous environments is of significant importance to applications in nanobiology, such as sensing, screening and protein adsorption studies. Here we describe a new instrument (a ''Snomipede'') that facilitates the parallel execution of SNPL under water using an AFM-style cantilever probe array and liquid cell. A feature size (full width at half maximum (FWHM)) of around 70nm has been achieved for dot arrays fabricated in parallel under water.

A prerequisite for any "lab on a chip" device that utilizes an electrical signal from the sensor protein is the ability to attach the protein in a specific orientation onto a conducting substrate. Here, we demonstrate the covalent attachment to a gold surface of light-harvesting membrane proteins, from Rhodobacter sphaeroides, via cysteine (Cys) residues engineered on either the cytoplasmic or periplasmic face. This simple directed attachment is superior in its ability to retain light-harvesting complex (LHC) function, when compared to a similar attachment procedure utilizing a self-assembled monolayer on gold. LH 1 has previously been observed to have superior photostability over LH 2 (Magis et al. [2010] Biochim. Biophys. Acta, 1798, 637-645); this characteristic is maintained even with the introduction of Cys residues. The integral membrane protein light-harvesting complex 2 of Rhodobacter sphaeroides has been engineered to express cysteine residues on either the cytoplasmic or periplasmic face of the complex. These cysteine residues permit the oriented attachment of the isolated complexes on a gold surface. The complexes are not denatured by this simple attachment procedure as demonstrated by fluorescence emission spectroscopy. © 2011 The Authors.

A history is given of liquid 3He research from the time when 3He first became available following World War II through 1972 when the discovery of the superfluid phases was made. The Fermi liquid nature was established early on, and the Landau Fermi liquid theory provided a framework for understanding the interactions between the Fermions (quasiparticles). The theory’s main triumph was to predict zero sound, which was soon discovered experimentally. Experimental techniques are treated, including adiabatic demagnetization, dilution refrigerator technology, and Pomeranchuk cooling. A description of the superfluid 3He discovery experiments using the latter two of these techniques is given. While existing theories provided a basis for understanding the newly discovered superfluid phases in terms of l>0 Cooper pairs, the unexpected stability of the A phase in the high-P, high-T region of the phase diagram needed for its explanation a creative leap beyond the BCS paradigm. The use of sum rules to interpret some of the unusual magnetic resonance in liquid 3He is discussed. Eventually a complete theory of the spin dynamics of superfluid 3He was developed, which predicted many of the exciting phenomena subsequently discovered.

Continued progress in the fast-growing field of nanoplasmonics will require the development of new methods for the fabrication of metal nanostructures. Optical lithography provides a continually expanding tool box. Two-photon processes, as demonstrated by Shukla et al. (doi: 10.1021/nn103015g), enable the fabrication of gold nanostructures encapsulated in dielectric material in a simple, direct process and offer the prospect of three-dimensional fabrication. At higher resolution, scanning probe techniques enable nanoparticle particle placement by localized oxidation, and near-field sintering of nanoparticulate films enables direct writing of nanowires. Direct laser "printing" of single gold nanoparticles offers a remarkable capability for the controlled fabrication of model structures for fundamental studies, particle-by-particle. Optical methods continue to provide a powerful support for research into metamaterials.

After a brief review of the phenomenology of superconductivity and of its generic explanation in terms of the concept of off-diagonal long-range order, I first survey the original Bardeen-Cooper-Schrieffer (BCS) weak-coupling model and some extensions of it. I then turn to systems such as the heavy fermions and the cuprates where the superconductivity is generally believed to be due to an all-electronic mechanism, and ask how much information we get about this mechanism from quite general energetic and other considerations, without committing ourselves to any particular microscopic model.

Photolithographic techniques have been used to fabricate polymer brush micro- and nanostructures. On exposure to UV light with a wavelength of 244 nm, halogens were selectively removed from films of chloromethylphenyltrichlorosilane and 3-(2-bromoisobutyramido)propyl-triethoxysilane on silicon dioxide. Patterning was achieved at the micrometer scale, by using a mask in conjunction with the incident laser beam, and at the nanometer scale, by utilizing interferometric lithography (IL). Friction force microscopy images of patterned surfaces exhibited frictional contrast due to removal of the halogen but no topographical contrast. In both cases the halogenated surface was used as an initiator for surface atom-transfer radical polymerization. Patterning of the surface by UV lithography enabled the definition of patterns of initiator from which micro- and nanostructured poly[oligo(ethylene glycol)methacrylate] bottle brushes were grown. Micropatterned brushes formed on both surfaces exhibited excellent resistance to protein adsorption, enabling the formation of protein patterns. Using IL, brush structures were formed that covered macroscopic areas (approximately 0.5 cm²) but exhibited a full width at half maximum height as small as 78 nm, with a period of 225 nm. Spatially selective photolytic removal of halogens that are immobilized on a surface thus appears to be a simple, rapid, and versatile method for the formation of micro- and nanostructured polymer brushes and for the control of protein adsorption.

The frictional properties of poly(2-(methacryloyloxy)ethylphosphorylcholine) (PMPC) brushes grown from planar silicon surfaces by atom transfer radical polymerization (ATRP) have been characterized using in situ friction force microscopy (FFM). The dry thicknesses of the PMPC brushes ranged from 20 to 421 nm. For brush layers with dry thicknesses greater than ca. 100 nm, the coefficient of friction decreased with increasing film thickness. For shorter brushes, the coefficient of friction varied little with brush thickness. We hypothesize that the amount of bound solvent increases as the brush length increases, causing the osmotic pressure to increase and yielding a reduced tendency for the brush layer to deform under applied load. A comparison of the force-displacement plots acquired for various PMPC brushes under water supports this hypothesis, since a greater repulsive force is measured for thicker brushes. FFM was also used to investigate the well-known co-nonsolvency behavior exhibited by PMPC chains. For a PMPC brush layer of 307 nm dry thickness, the friction force was determined as a function of the volume fraction of alcohol in alcohol/water mixtures. Unlike a previous macroscopic study, a significant increase in the coefficient of friction was observed for ethanol/water mixtures at a volume fraction of 90%. This is attributed to brush collapse due to co-nonsolvency, leading to loss of hydration of the brush chains and hence substantially reduced lubrication. Force measurements normal to the surface indicate much greater hysteresis between approaching and retraction curves under co-nonsolvency conditions. However, no such effect was observed for 2-propanol/water and methanol/water mixtures over a wide range of volume fractions, in agreement with recent ellipsometric studies of PMPC brushes.

An approach to the integration of nanolithography with synthetic chemical methodology is described, in which near-field optical techniques are used to selectively deprotect films formed by the adsorption of aminosilanes protected by modified 2-nitrophenylethoxycarbonyl (NPEOC) groups. The NPEOC groups are functionalized at the m- or p-position with either a tetraethyleneglycol or a heptaethylene glycol adduct. We describe the synthesis of these bioresistant aminosilanes and the characterization of the resulting photoreactive films. Photodeprotection by exposure to UV light (λ = 325 nm) yielded the amine with high efficiency, at a similar rate for all four adsorbates, and was complete after an exposure of 2.24 J cm(-2). Following photodeprotection, derivatization by trifluoroacetic anhydride was carried out with high efficiency. Micropatterned samples, formed using a mask, were derivatized with aldehyde-functionalized polymer nanoparticles and, following derivatization with biotin, were used to form patterns of avidin-coated polymer particles. Fluorescence microscopy and atomic force microscopy data demonstrated that the intact protecting groups conferred excellent resistance to nonspecific adsorption. Nanometer-scale patterns were created using scanning near-field photolithography and were derivatized with biotin. Subsequent conjugation with avidin-functionalized polymer nanoparticles yielded clear fluorescence images that indicated dense attachment to the nanostructures and excellent protein resistance on the surrounding surface. These simple photocleavable protecting group strategies, combined with the use of near-field exposure, offer excellent prospects for the control of surface reactivity at nanometer resolution in biological systems and offer promise for integrating the top-down and bottom-up molecular fabrication paradigms.

Iranian scientists are growing increasingly isolated because of political tensions between Iran and the West. We attempt to alleviate this problem through science diplomacy.

The “Millipede”, developed by Binnig and co-workers (Bining, G. K.; et al. IBM J. Res. Devel. 2000, 44, 323.), elegantly solves the problem of the serial nature of scanning probe lithography processes, by deploying massive parallelism. Here we fuse the “Millipede” concept with scanning near-field photolithography to yield a “Snomipede” that is capable of executing parallel chemical transformations at high resolution over macroscopic areas. Our prototype has sixteen probes that are separately controllable using a methodology that is, in principle, scalable to much larger arrays. Light beams generated by a spatial modulator or a zone plate array are coupled to arrays of cantilever probes with hollow, pyramidal tips. We demonstrate selective photodeprotection of nitrophenylpropyloxycarbonyl-protected aminosiloxane monolayers on silicon dioxide and subsequent growth of nanostructured polymer brushes by atom-transfer radical polymerization, and the fabrication of 70 nm structures in photoresist by a Snomipede probe array immersed under water. Such approaches offer a powerful means of integrating the top-down and bottom-up fabrication paradigms, facilitating the reactive processing of materials at nanometer resolution over macroscopic areas.

Following the success of the original BCS theory as applied to superconductivity in metals, it was suggested that the phenomenon of Cooper pairing might also occur in liquid 3- He , though unlike the metallic case the pairs would most likely form in an anisotropic state, and would then lead in this neutral system to superfluidity. However, what had not been anticipated was the richness of the phenomena which would be revealed by the experiments of 1972. In the first place, even in a zero magnetic field there is not one but two superfluid phases, and the explanation of this involves ideas concerning "spin fluctuation feedback" which have no obvious analog in metals. Secondly, the anisotropic nature of the pair wave function, which in the case of the B phase is quite subtle, and the fact that the orientation must be the same for all the pairs, leads to a number of qualitatively new effects, in particular to a spectacular amplification of ultra-weak interactions seen most dramatically in the NMR behavior. In this chapter I review the application of BCS theory to superfluid 3- He with emphasis on these novel features.

We demonstrate that interferometric lithography provides a fast, simple approach to the production of patterns in self-assembled monolayers (SAMs) with high resolution over square centimeter areas. As a proof of principle, two-beam interference patterns, formed using light from a frequency-doubled argon ion laser (244 nm), were used to pattern methyl-terminated SAMs on gold, facilitating the introduction of hydroxyl-terminated adsorbates and yielding patterns of surface free energy with a pitch of ca. 200 nm. The photopatterning of SAMs on Pd has been demonstrated for the first time, with interferometric exposure yielding patterns of surface free energy with similar features sizes to those obtained on gold. Gold nanostructures were formed by exposing SAMs to UV interference patterns and then immersing the samples in an ethanolic solution of mercaptoethylamine, which etched the metal substrate in exposed areas while unoxidized thiols acted as a resist and protected the metal from dissolution. Macroscopically extended gold nanowires were fabricated using single exposures and arrays of 66 nm gold dots at 180 nm centers were formed using orthogonal exposures in a fast, simple process. Exposure of oligo(ethylene glycol)-terminated SAMs to UV light caused photodegradation of the protein-resistant tail groups in a substrate-independent process. In contrast to many protein patterning methods, which utilize multiple steps to control surface binding, this single step process introduced aldehyde functional groups to the SAM surface at exposures as low as 0.3 J cm(-2), significantly less than the exposure required for oxidation of the thiol headgroup. Although interferometric methods rely upon a continuous gradient of exposure, it was possible to fabricate well-defined protein nanostructures by the introduction of aldehyde groups and removal of protein resistance in nanoscopic regions. Macroscopically extended, nanostructured assemblies of streptavidin were formed. Retention of functionality in the patterned materials was demonstrated by binding of biotinylated proteins.

The aqueous speciation of trivalent lanthanide and actinide cations in solutions containing DTPA (diethylenetriamine-N,N,N′,N′,N′′-pentaacetic acid) and lactic acid were studied under conditions representative of the TALSPEAK process. Spectrophotometric titrations, fluorescence spectroscopy, and thermometric titrations were used to search for indications of ternary metal-DTPA-lactate complexes. The addition of lactate anions to metal-DTPA complexes was undetectable by any of these techniques, even at free lactate concentrations of 0.75 M. Although lactic acid is necessary for the optimal performance of the TALSPEAK process, we find that the fractions of aqueous ternary Ln3+/An3+-DTPA-lactate complexes are far too low to account for the observed acid dependence of TALSPEAK metal extraction.

The UV photodegradation of protein-resistant poly(oligo(ethylene glycol) methacrylate) (POEGMA) bottle-brush films, grown on silicon oxide by surface-initiated atom radical transfer polymerization, was studied using X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Exposure to light with a wavelength of 244 nm caused a loss of polyether units from the brush structure and the creation of aldehyde groups that could be derivatized with amines. An increase was measured in the coefficient of friction of the photodegraded polymer brush compared to the native brush, attributed to the creation of a heterogeneous surface film, leading to increased energy dissipation through film deformation and the creation of new polar functional groups at the surface. Exposure of the films through a photomask yielded sharp, well-defined patterns. Analysis of topographical images showed that physical removal of material occurred during exposure, at a rate of 1.35 nm J(-1) cm(2). Using fluorescence microscopy, the adsorption of labeled proteins onto the exposed surfaces was studied. It was found that protein strongly adsorbed to exposed areas, while the masked regions retained their protein resistance. Exposure of the film to UV light from a scanning near-field optical microscope yielded submicrometer-scale patterns. These data indicate that a simple, rapid, one-step photoconversion of the poly(OEGMA) brush occurs that transforms it from a highly protein-resistant material to one that adsorbs protein and can covalently bind amine-containing molecules and that this photoconversion can be spatially addressed with high spatial resolution.

The optical and electrical properties of dodecanethiol-stabilized nanoparticles (6 nm diameter gold core) have been investigated over a range of film thicknesses and temperatures. The surface plasmon resonance absorbance is found to be dependent on temperature. Heating of the nanoparticle film causes desorption of the thiol from the surface of the gold nanoparticle, resulting in irreversible changes to the absorption spectra of the nanoparticle film. Atomic force microscopy images of the samples before and after heating for different film thicknesses reveal structural changes and increased domain connectivity for thicker films leading to sub-10 ohm resistances measured for the 15-layer film.

The synthesis of alpha-thioacetate terminated quaterthiophene and phenylene-thiophene materials, possessing thioacetate, oxetane, and alkyl groups at their omega-termini, is described. After deprotection these molecules were adsorbed onto Au films and the resulting self-assembled monolayers were characterized by X-ray photoelectron spectroscopy (XPS) and friction force microscopy (FFM). FFM indicated that monolayers formed by the dithioacetates had the highest coefficients of friction, followed by the oxetane-terminated adsorbates, with the alkyl-functionalized materials showing the lowest friction coefficients. These data may be understood in terms of differences in molecular packing. The quaterthiophene adsorbates also yielded higher friction coefficients than their phenylene-thiophene counterparts. Micrometer-scale patterns were fabricated by mask-based exposure to 244 nm light, and characterized by FFM. Nanometer-scale patterns were fabricated using near-field exposure and characterized by FFM. The images obtained demonstrated that features of conjugated oligomers with high spatial resolution (59 nm, ca. lambda/4) were achievable.

This paper presents the results of a study targeted at characterising the oxidation behaviour of a new nickel based disc alloy (RR1000) at intermediate temperatures. Isothermal exposures were carried out using a thermo-microbalance at temperatures in the range 700 – 800°C for exposures up to 200 hours. Cyclic oxidation exposures were carried out at, 700 and 750°C for up to 1000 hours with 100 hour cycles, using mass change to monitor the materials performance. The mass gain data obtained have been used to derive oxidation reaction rate parameters, using established methodologies, with parabolic rate constants varying between 1.4×10–5 mg2/cm4/h at 700°C and 8.4×10–4 mg2/cm4/h at 800°C.Surface oxides were initially analysed using scanning electron microscope/energy dispersive X-ray analysis (SEM/EDX) and X-ray diffraction (XRD) techniques. The results showed that slowly-growing chromium-rich oxide scales had formed on the surface of the samples during these exposures. A more detailed study of cross-...

Studies of the UV-induced photodegradation of poly(ethylene terephthalate) (PET) have been carried out using contact-angle goniometry, X-ray photoelectron spectroscopy (XPS), and friction force microscopy (FFM). The advancing contact angle of water, theta, decreased following exposure of free-standing PET films to UV light. Measurements of surface friction by FFM showed that the coefficient of friction mu increased as the degradation proceeded, reaching a limiting value after ca 200 min, in agreement with the contact angle data. Using a modified form of the Cassie equation, a quantitative analysis of the extent of modification could be carried out. There was a very close correlation between the coefficient of friction determined by FFM and the value of cos theta. XPS provided more detailed information on surface bonding that also correlated closely with the FFM data. Although FFM provides quantitative data on surface modification with nanometer-scale spatial resolution, it does not provide detailed structural information such as is provided by XPS. The oxygen content at the surface was found to increase as photo-generated radicals within the PET reacted with atmospheric oxygen. Increases in both ester and carbonyl contributions within XPS data accompanied this increase. It was concluded that the photodegradation process follows mainly Norrish type I reaction pathways, following previous work by Fechine et al and Grosstete et al.

Central to the advancement of friction force microscopy (FFM) as a quantitative surface analysis technique is the establishment of clear relationships between the organization and composition of surfaces and data acquired from FFM. As a step toward this goal, FFM has been applied to measurement of the kinetics of a surface-confined reaction, namely, the esterification of alcohol-terminated self-assembled monolayers (SAMs) by trifluoroacetic anhydride. The kinetics were studied initially using contact angle goniometry. The data obtained were found to be well described by a Langmuir adsorption isotherm. The progress of the reaction was also monitored by X-ray photoelectron spectroscopy, and comparative studies carried out using FFM. By using a simple numerical analysis of the FFM data, it has been possible to obtain quantitative information on surface composition. The resulting measurements of the fraction of derivatized molecules have been compared with compositional data obtained from XPS and contact angle goniometry, and found to be in excellent agreement, establishing unequivocally the capability of FFM as a quantitative surface analysis technique.

The frictional properties of spun-cast films of polystyrene and poly(methyl methacrylate) (PMMA) have been characterized using friction force microscopy (FFM). In air, the friction-load relationship was found to obey Johnson-Kendall-Roberts mechanics, but under ethanol, it was found to fit Amontons' Law. The coefficient of friction measured under ethanol was found to increase with increasing molecular weight, up to a molecular weight close to the bulk critical molecular weight for entanglement. At greater values than this, the coefficient of friction changed comparatively little with molecular weight. It is suggested that at molecular weights below Mc, the frictional interaction is dominated by plowing of the tip between polymer molecules; as molecular weight increases, so the viscosity of the film increases and the coefficient of friction increases. After the onset of entanglement, the mechanism of energy dissipation changes to one in which the tip sticks in loops of polymer between entanglements, extending the chains until at a critical stress, the contact is broken. The frictional interaction is thus comparatively invariant with molecular weight. FFM was also used to investigate the kinetics of the UV-induced modification of PMMA. A progressive decrease in the coefficient of friction was observed as a function of the time that the film was exposed to UV light, a result which was correlated to a gradual reduction in the molecular weight of the polymer and, hence, the entanglement density of the system.

U-Pb ages and Nd isotope values of Proterozoic rocks in Sonora, Mexico, indicate the presence of Caborca-type basement, predicted to lie only south of the Mojave-Sonora mega-shear, 40 km north of the postulated megashear. Granitoids have U-Pb zircon ages of 1763–1737 Ma and 1076 Ma, with ϵNd(t) values from +1.4 to −4.3, typical of the Caborca block. Lower Jurassic strata near the Proterozoic rocks contain large granitic clasts with U-Pb ages and ϵNd(t) values indistinguishable from those of Caborcan basement. Caborca-type basement was thus present at this location north of the megashear by 190 Ma, the depositional age of the Jurassic strata. The Proterozoic rocks are interpreted as parautochthonous, exhumed and juxtaposed against the Mesozoic section by a reverse fault that formed a footwall shortcut across a Jurassic normal fault. Geochronology, isotope geochemistry, and structural geology are therefore inconsistent with Late Jurassic megashear displacement and require either that no major transcurrent structure is present in Sonora or that strike-slip displacement occurred prior to Early Jurassic time.

The photolithographic modification of monolayers provides a versatile and powerful means of fabricating functionalized nanostructured surfaces. In this contribution, we present photosensitive thiol-bearing aryl ester groups which are capable of undergoing the so-called photo-Fries rearrangement to yield hydroxyketones. Phenyl 16-mercaptohexadecanoate was prepared by a three-step synthesis. This molecule undergoes a photoisomerization reaction upon illumination with UV light at ca. 250 nm. Subsequently this molecule was applied as a self-assembled monolayer on gold. Following photochemical modification, the adsorbates were selectively derivatized to yield amino-functionalized surfaces using a simple two-step reaction. This reaction was monitored by X-ray photoelectron spectroscopy and contact angle measurements and friction force microscopy. Micrometer-scale patterned surfaces were produced using a contact mask in conjunction with a frequency-doubled argon ion laser (lambda=244 nm). Near-field optical exposure was carried out by coupling the laser to a scanning near-field optical microscope and yielded nanometer-scale resolution. Following derivatization, the resulting structures were analyzed by friction force microscopy. Clear contrast was observed in the friction signal following surface modification.

Photo-deprotectable self-assembled monolayers (SAMs) provide a versatile platform for creating functional patterned surfaces. In this study, we present nanoscale photo-patterning, multi-component patterning, and a method for producing molecular gradients using photo-deprotectable SAMs. Nanoscale patterning of photo-deprotectable SAMs was achieved by coupling a UV laser (365 nm) through a scanning near field probe to produce nanoscale lines of ∼40 nm, i.e. λ/9. Multi-component patterning was achieved by a two-stage method combining both microcontact printing and soft-UV photo-patterning. The example demonstrated in this study produced a three-component patterned surface with regions of CF3, CH3 and COOH/CF3 functionality. The versatility of these photocleavable SAMs is further demonstrated by creating linear molecular gradients of two functionalities along a distance of ∼25 mm. The use of ‘soft’ UV gives several advantages including the ability to pattern SAMs with micron-scale features over large areas qu...

Near-field optical methods offer unique potential in nanofabrication, because they provide the capacity to initiate highly selective chemical transformations with nanometer scale precision. The basic principles behind scanning near-field photolithography (SNP), in which a scanning near-field optical microscope coupled to a UV laser is used to initiate surface chemical reactions, are described. The fundamental principles underlying the patterning of self-assembled monolayers by SNP are described, and the resolution limits and the basic principles that enable routine achievement of sub-50 nm resolution are discussed. Illustrations are provided of the application of SNP to the patterning of protein molecules on gold surfaces. The patterning of molecular adsorbates on oxide surfaces, including the fabrication of highly miniaturized arrays of DNA on silicon dioxide, is also described. It is argued that SNP holds great promise for the organization of biomolecules on nanometer length scales.

Gradients of surface chemical composition were prepared by performing a selective photo-oxidation of self-assembled monolayers (SAMs) of alkanethiols adsorbed on a gold surface, using an ultraviolet laser (244 nm) coupled to an etched optical fiber. In the center of the exposed region, uniform oxidation occurs facilitating uniform replacement of the oxidation products with a second, contrasting thiol, while at the perimeter of the exposed region a gradient of exposure occurs, leading to a gradient of photochemical reaction and, following immersion of the sample in a solution of a contrasting thiol, a gradient of composition. Variation in the exposure is possible by varying the time or the power, and both the height and the width of the resulting gradient may be controlled straightforwardly yielding a simple but highly effective means of generating molecular-scale chemical gradients.

Self-assembled monolayers of alkylphosphonic acids (APA) have been patterned at the micrometer and nanometer scale by photochemical methods. Exposure of APA monolayers to light with a wavelength of 244 nm leads to scission of the C−P bond and desorption of the alkyl chain from the surface. Immersion of the specimen in a solution of a second APA leads to adsorption at the surface in the exposed regions. Immersion in a solution of hydroxide ions leads to etching of the exposed regions of the aluminum film. UV exposure appears to anneal the aluminum oxide film, conferring increased resistance to etching at high exposures and a switching the function of the monolayer from a positive to a negative tone resist. At intermediate exposures, nanoscale trenches form at the perimeters of exposed regions. Near-field exposure of the phosphonic acid structures, using a UV laser coupled to a scanning near-field optical microscope, yields well-defined nanostructured features following development of the pattern in aqueous...

The UV photo-oxidation of oligo(ethylene glycol) (OEG)-terminated self-assembled monolayers (SAMs) has been studied using static secondary ion mass spectrometry, X-ray photoelectron spectroscopy, contact angle measurement, and friction force microscopy. OEG-terminated SAMs are oxidized to yield sulfonates, but photodegradation of the OEG chain also occurs on a more rapid time scale, yielding degradation products that remain bound to the surface via gold-sulfur bonds. The oxidation of these degradation products is the rate-limiting step in the process. Photopatterning of OEG-terminated SAMs may be accomplished by using a mask and suitable light source or by using scanning near-field photolithography (SNP) in which the mask is replaced by a scanning near-field optical microscope coupled to a UV laser. Using SNP, it is possible to fabricate patterns in SAMs with a full width at half-maximum height (fwhm) as small as 9 nm, which is approximately 15 times smaller than the conventional diffraction limit. SNP-patterned OEG-terminated SAMs may be used to fabricate protein nanopatterns. By adsorbing carboxylic acid-terminated thiols into oxidized regions and converting these to active ester intermediates, it has been possible to fabricate lines of protein molecules with widths of only a few tens of nanometers.

I present the motivation for experiments which attempt to generate, and verify the existence of, quantum superpositions of two or more states which are by some reasonable criterion “macroscopically” distinct, and show that various a priori objections to this program made in the literature are flawed. I review the extent to which such experiments currently exist in the areas of free-space molecular diffraction, magnetic biomolecules, quantum optics and Josephson devices, and sketch possible future lines of development of the program.

In recent years, Dynamic Nuclear Polarization (DNP) has re-emerged as a means to ameliorate the inherent problem of low sensitivity in nuclear magnetic resonance (NMR). Here, we present a novel approach to DNP enhanced liquid-state NMR based on rapid melting of a solid hyperpolarized sample followed by 'in situ' NMR detection. This method is applicable to small (10nl to 1μl) sized samples in a microfluidic setup. The method combines generic DNP enhancement in the solid state with the high sensitivity of stripline (1)H NMR detection in the liquid state. Fast cycling facilitates options for signal averaging or 2D structural analysis. Preliminary tests show solid-state (1)H enhancement factors of up to 500 for H2O/D2O/d6-glycerol samples doped with TEMPOL radicals. Fast paramagnetic relaxation with nitroxide radicals, In nonpolar solvents such as toluene, we find proton enhancement factors up to 400 with negligible relaxation losses in the liquid state, using commercially available BDPA radicals. A total recycling delay (including sample freezing, DNP polarization and melting) of about 5s can be used. The present setup allows for a fast determination of the hyper-polarization as function of the microwave frequency and power. Even at the relatively low field of 3.4T, the method of rapid melting DNP can facilitate the detection of small quantities of molecules in the picomole regime.

A novel poly(amino acid methacrylate) brush comprising zwitterionic cysteine groups (PCysMA) was utilized as a support for lipid bilayers. The polymer brush provides a 12-nm-thick cushion between the underlying hard support and the aqueous phase. At neutral pH, the zeta potential of the PCysMA brush was ∼-10 mV. Cationic vesicles containing25% DOTAP were found to form a homogeneous lipid bilayer, as determined by a combination of surface analytical techniques. The lipid mobility as measured by FRAP (fluorescence recovery after photobleaching) gave diffusion coefficients of ∼1.5 μm(2) s(-1), which are comparable to those observed for lipid bilayers on glass substrates.

In 1964, the year in which the present author obtained his doctorate, the highest known transition temperature Tc to the superconducting state was around 20 K. In that year, Professor Vitaly Ginzburg made a striking prediction; building on the work of Little [1], who had proposed a purely electronic mechanism to raise Tc, he predicted [2] that transition temperatures of the order of room temperature would indeed some day be achieved, and moreover that this was most likely to happen in a strongly layered (quasi-two-dimensional) system (rather than in the one-dimensional systems that Little had considered). As is well known, both these predictions were verified 22 years later, when transition temperatures over 90 K (subsequently raised to over 160 K) were realized in a class of cuprate materials whose most striking structural feature is indeed their metallic CuO2 planes separated by much less conducting materials. I would like, therefore, to devote this brief essay to the question: What is the role, in the genesis of high-temperature superconductivity in the cuprates, of the quasi-two-dimensionality of the CuO2 planes? In particular, I shall be interested in the question (which has, of course, already attracted much attention in the literature): why, in the various homologous cuprate series (T1, Hg, Bi, etc.) does Tc show a characteristic and reproducible dependence (see below) on the number n of CuO2 planes per multilayer? Let me start with a couple of remarks about the raw data. First, it seems to be a rather general observation, not confined to the cuprates, that compared to other materials in their general class, strongly layered materials have rather high transition tempera

The settlement and adhesion of Navicula perminuta and Ulva linza to methyl-terminated alkanethiol self-assembled monolayers (SAMs) of increasing chain length has been investigated. Organisms were allowed to settle onto the monolayers and were subsequently exposed to hydrodynamic shear stress in order to determine their adhesion strength. Results show that as the SAM structure changes from amorphous to crystalline (C14), there is a marked change in the adhesion of N. perminuta and U. linza . Given that the SAMs in the series all exhibit similar contact angle behaviour and surface energy, it is hypothesized that the lubricity of the surface plays a role in determining the surface adhesion.

Monolayers of alkylphosphonic acids (APA) and alkylcarboxylic acids (ACA) on magnetron-sputtered aluminum films have been investigated by friction force microscopy (FFM), contact angle measurement, and polarization-modulation infrared reflection-absorption spectroscopy (PM-IRRAS). Clear evidence has been provided from PM-IRRAS that friction coefficients, determined from FFM data, may be correlated directly with variations in adsorbate molecular structure. The friction coefficient increased with the length of the adsorbate molecule, but reached a limiting value when the alkyl chain of the adsorbate contained eight carbons in the case of APA or 12 carbons in the case of ACA. For a given alkyl chain length, APA monolayers yielded coefficients of friction that were similar to those of monolayers of alkylthiols of the same length, but smaller than those of ACA. These data indicate that APA monolayers are better ordered than ACA monolayers. These inferences were supported by PM-IRRAS data, which enabled the density of gauche defects to be estimated and correlated with variations in the coefficient of friction.

Multiuse pilot-scale plants often run production campaigns in parallel, requiring frequent changes in the chemistry from campaign to campaign and modified procedures to match the new production needs within a short time span. Facilities must also match clients' product chemistry and process demands with their equipment capabilities. These campaigns may occur several times a year with considerable overlap of projects. Several basic but important questions arise for the facility manager. For example, how do the facilities' personnel pay adequate attention to all of the safety issues associated with the chemical reactivity? ensure that a facility's equipment and the new process chemistry fit together safely, especially with respect to chemical reactivity? verify emergency relief and vent sizing, estimate cooling duty needs, and implement the necessary process safety changes? This paper introduces a new approach and procedure that assists plant personnel to assess the process and identify the potential hazards. The procedure also recommends a methodology to evaluate the nature and extent of the hazard. © 2006 American Institute of Chemical Engineers Process Saf Prog, 2006

Exposure of thiol-stabilized gold nanoparticles supported on silicon wafers to UV light leads to oxidation of the thiol molecules and coagulation of the nanoparticles, forming densified structures that are resistant to removal by solvent exposure. Unoxidized particles may, in contrast, readily be removed leaving gold structures behind at the surface. This process provides a convenient and simple route for the fabrication of gold structures with dimensions ranging from micrometers to nanometers. The use of masks enables micrometer-scale structures to be fabricated rapidly. Exposure of nanoparticles to light from a near-field scanning optical microscope (NSOM) leads to the formation of gold nanowires. The dimensions of these nanowires depend on the method of preparation of the film: for spin-cast films, a width of 200 nm was achieved. However, this was reduced significantly, to 60 nm, for Langmuir-Schaeffer films.

Self-assembled monolayers (SAMs) of alkanethiols have been patterned on micrometre and nanometre length scales by exposure to light from a frequency doubled argon ion laser. Friction force microscopy shows that the patterning speed depends on the nature of the terminal group and is in the order COOH> CH3, the reverse of the order reported previously using a mercury arc lamp, indicating that a different photo-oxidation mechanism is responsible. It is suggested that this involves the creation of hot electrons at the gold surface that initiate oxidation of the adsorbate. Nanostructures have been fabricated using scanning near-field photolithography (SNP), in which the UV laser is coupled to a near-field scanning optical microscope. During SNP, the rates of writing required for complete oxidation correlate closely with oxidation rates measured during micropatterning, suggesting that the mechanism is essentially the same. SAMs on silver have been patterned, yielding linewidths smaller than 50 nm. The selective alkylation of hydrogen passivated Si has been demonstrated, yielding structures that may be used as resists for etching and demonstrating a powerful new capability—fluid-phase nanophotolithography. Patterned SAMs prepared using SNP have been used to selectively attach polymer nanoparticles, demonstrating their utility for the creation of functional molecular nanostructures. Nanopatterns generated by SNP have also been used as resists, enabling the etching of nanostructures into gold and the fabrication of three-dimensional nanostructures in silicon using a two-stage wet etch process.

Study objectives To determine the prevalence of gastroesophageal reflux disease (GERD)—both symptoms and objective evidence—using 24-h dual-probe pH monitoring in difficult asthma, and the relationship between the presence and treatment of GERD to clinical outcome Design and setting As part of a systematic evaluation protocol, 68 subjects with difficult-to-control asthma attending a difficult asthma clinic were referred for dual-probe ambulatory pH esophageal monitoring Results Esophageal probe data were available in 52 patients (76%) with difficult asthma. The prevalence of GERD/GERD-associated asthma symptoms was 75% (39 of 52 patients; 95% confidence interval [CI], 63 to 84.7%). The prevalence of GERD as evidenced by an abnormal pH profile at the distal esophageal probe was 55% (29 of 52 patients; 95% CI, 40 to 69%). The prevalence of GERD at the proximal probe was 34.6% (18 of 52 patients; 95% CI, 23.6 to 51%). The prevalence of GERD was similar in asthmatic subjects who responded to intervention and those who remained difficult to control (therapy resistant). Asymptomatic GERD was present in 9.6% (5 of 52 patients); 16% of cough episodes correlated with acid reflux Conclusions In difficult-to-control asthma, GERD is common, but identification and treatment of GERD do not appear to relate to improvement in asthma control in this population

Contact mode scanning force microscopy was employed to produce permanent deformation in polystyrene films of molecular weight ranging from 5 to 483 kg mol−1. Operating in a regime of small loads and a low number of scan cycles, a variety of wear types was observed, including the formation of grooves and bundles. These differences could be explained in terms of the entanglement density at the film surface. For completely disentangled films, long parallel grooves formed at the lateral edges of the scanned area as a consequence of molecular displacement. In the central region, wide bundles formed after only a few passages. For fully entangled films, discontinuous ridges were immediately generated with a much reduced spacing. A transition in wear behaviour occurred when, for molecular weight between 13 and 64 kg mol−1, entanglement was not fully developed. In this regime, the entanglement degree could be evaluated via measuring the threshold load at which fragments of material were torn off from the surface. Nanowear induced in such a controlled fashion on unknown polymeric surfaces can yield important insights into surface molecular organization.

The objective of this article is to evaluate (via modeling) the impact of different pollution control scenarios on the shape of the income-emissions relationship. The simulation of emissions and emission controls was conducted using the Climate Change Risk Assessment Framework, which projects SO2 and NOx emissions from energy consumption and conversion and non-energy sources. The analysis of resulting scenario-, region-, and gas-specific income-emission curves suggests that income alone as a model driver of future emissions cannot adequately capture all plausible future SO2 or NOx emission pathways, or important differences among regions in those trajectories. Future social choices regarding the degree and strategy for environmental protection introduce large uncertainties in future projections and result in differing relationships between income and emissions. The analysis also suggests that the inverted-U shape (hypothesized Environmental Kuznets Curve) is only one of several plausible forms of the future relationship between income and emissions.

The element helium comes in two (stable) forms. 4 He and 5 He; at low temperatures and pressures both form liquids rather than solids. The liquid phase of the common isotope, ' 1 He, was realized' nearly a century ago, and since 1938 has been known to show, at temperatures below about 2 K, the property of superfluidity-the ability to flow through the narrowest capillaries without apparent friction. The light isotope, 2 He, is believed to be of quite a different nature; however,because of its similarity to the electrons in metals, which at low temperatures sometimes form Cooper pairs and thereby become superconducting, theorists in the 1960s and early 1970s had speculated that something similar might happen in liquid 3 He, which would then also show superfluidity though for reasons rather different than 4 He. In 1972 nuclear magnetic resonance (NMR) experiments at Cornell University revealed the existence, below 3 millidegrees, if two new phases, one of which displayed extraordinary NMR properties. Anthony Leggett is one of the theorists who succeeded in fitting the experimental properties into the Cooper-pairing scenario; in particular, he explained the NMR behavior and predicted further novel NMR phenomena which were subsequently found.

Molecular features with widths of only 20 nm have been fabricated in self-assembled monolayers of alkanethiols on gold using a new lithographic tool, scanning near-field photolithography, based upon the use of a near-field scanning optical microscope (NSOM) coupled to a UV laser. Quite unexpectedly it has proved possible to routinely fabricate structures significantly smaller than the aperture in the NSOM probe. This exceptional performance is strongly correlated with the morphology of the gold film. In particular, the best results are achieved on films with comparatively small grain sizes. In contrast, the use of atomically flat, epitaxially deposited gold films leads to a minimum feature size comparable to the aperture diameter (ca 50 nm). It is concluded that nonradiative interactions (possibly the excitation of surface plasmons) between the gold substrate and the fiber lead to a pronounced focusing of the electric field beneath the aperture.

By using small inclusions of liquid 3 He trapped in a solid 4 He matrix, it may be possible to study a sample of the superfluid A phase in the regime where quantum fluctuations of the relative phase of the “up” and “down” Cooper pairs are no longer negligible. Under these conditions there is little doubt that a standard quantum-mechanical (QM) calculation of the NMR dynamics should correctly describe the behavior of the total magnetization of a large ensemble of independent inclusions. However, it is less obvious that it should describe the behavior of a single inclusion on a single run of the experiment, and indeed it is tempting to argue that a “spontaneous breaking of the symmetry” corresponding to the relative phase should occur, analogously to what (allegedly) happens in the interference of two independent Bose condensates. Here I argue that the prima facie analogy is misleading, and that the QM calculation indeed describes the behavior of a single inclusion.

This paper advances the thesis that a complete assessment of the chemical process safety must be founded on specific chemical hazards data. Usually, these data can only be obtained from appropriately designed experiments using the correct testing techniques. The basis of safety and the window of safe operations arise from the relevant process safety data. BakerRisk's experience with the chemical processing industry (CPI) has shown that the PSM elements Safety Information, Process Hazards Analysis, and Operating Procedures are often documented without adequate hazards test data for the covered process. The information is often qualitative; it may be taken from inappropriate laboratory data and may not address the specific process deviation or worst-case situation(s). This lack of hazards test data represents an information void that tabletop or literature process hazard analyses alone cannot fill. Five observations and recommendations are offered: Chemical process safety supported by hazards testing is the right thing to do, whether the process is covered or not and whether the process is at the manufacturing stage or not; Hazards testing to identify and evaluate potential upset conditions should be an integral part of a company's process safety program. It is a major information source for process hazard analyses; The information obtained is specific to the thermodynamics and kinetics of the process chemistry; The information enables clear identification of operational, thermal, and reactivity hazards of processes involving highly hazardous chemicals; The scope of the chemical hazards testing should be matched with the quantities of chemicals involved and the development stage of the product. © 2004 American Institute of Chemical Engineers Process Saf Prog 23: 163–169, 2004

Aligned regularly spaced ridges form immediately on scanning the surface of uniaxially oriented poly(ethylene terephthalate) (PET) at applied loads of greater than 15 nN. This contrasts with nanowear of biaxially oriented PET film studied previously [B.D. Beake, et al., Polymer 42 (2001) 7025], which proceeds more slowly over a number of scan cycles by fatigue wear. Differences in nanowear are interpreted in terms of the differences in crystallinity and mechanical properties with processing history. Nanoindentation shows that the biaxially oriented material is harder, higher modulus and has a higher H/E ratio. It is suggested that the stick-slip process that leads to the formation of regularly spaced ridges on the polymeric surface proceeds smoothly on the uniaxially oriented PET film as the yield threshold for plastic deformation is exceeded at these contact pressures. The higher crystallinity of the biaxially oriented material results in a higher yield stress thus imparting a barrier to the stick-slip process. It is necessary for some local damage to occur over a number of scan cycles before the surface has a low enough yield stress that the stick-slip process can proceed efficiently. Results are compared to the nanowear of other polymeric materials and a map of the major deformation processes in nanowear is proposed for the first time. © 2003 Elsevier B.V. All rights reserved.