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The Montreal Urban Snow Experiment was dedicated to furthering the understanding of micrometeorological processes involved in the late winter-early spring transition period in a Canadian city. A surface energy budget (SEB) measurement site was installed in a dense residential area of Montreal for several weeks in 2005 and 2006. This paper focuses on the last 6 days of the 2006 experiment (23-28 March 2006), after snowmelt and before vegetation became active, with the objectives of providing a better understanding of physical processes involved during this transition period and examining their impact on the SEB. The Town Energy Balance urban canopy model and the Interactions between Soil, Biosphere, and Atmosphere force-restore land surface model are used in stand-alone mode and are forced with meteorological data measured at the top of a 20-m AGL instrumented tower. Preliminary results reveal deficiencies in the models' ability to simulate the surface energy budget partitioning, and in particular show overestimation of the sensible heat flux. Sensitivity studies indicate that a large portion of these problems is related to the latent heat transfer involved in natural soil freeze/thaw processes, which has a significant effect on the surface energy budget in this urban area. It is also found that the SEB in this particular situation is very sensitive to the thermal roughness length used for local energy exchange over the roof and road surfaces. DOI: 10.1175/2009JAMC2153.1

The effects of modifying features of the force field and their effects on the properties of the liquid are discussed.

The rapid and slow thermal decomposition of an energetically unstable polycyclic and heterocyclic azide, triazido-s-heptazine ([C.sub.6][N.sub.16]) (TAH), is described for producing nitrogen rich C[N.sub.x] materials. It is found that rapid methods produced porous spongelike structures, while slow decomposition methods produced faceted structures almost similar to microcrystalline precursor powder.

Two modern, fundamentally different methods were used for a detailed investigation of enantioselective drug--protein interactions, a surface plasmon resonance (SPR)-based Biacore 2000 biosensor assay and the previously validated HPLC perturbation method (HPLC-PM). This is the first time SPR has been used for this purpose. The fundamental features of the two methods were investigated, and the consequences for operation and data evaluation were addressed. With HPLC-PM, chiral data could be obtained directly from the racemic mixture, whereas a separate analysis of each pure enantiomer was required to obtain chiral data with SPR. It was shown that if chirality is not attributed in the SPR analysis, misleading average racemic binding constants will be obtained. Both drug and protein consumption were considerably higher with HPLC-PM. HPLC-PM was found to be best suited for measurements of weak affinity interactions, whereas the SPR method was best for strong interactions. With both methods, the presence of DMSO in the samples severely affected the interactions, introducing errors. The binding of the [beta]-blockers alprenolol and propranolol to Cel7a cellulase was used as a model system. These methods gave results that agreed quite well qualitatively, but considerable quantitative deviations were sometimes obtained.

We describe the design of a novel in vitro assay to study the interaction of soluble proteins with small hydrophobic sterol ligands. The sterol molecules are incorporated in an artificial membrane system in order to mimic their arrangement found in a biomembrane. The artificial membrane setup is monitored in real time by surface plasmon spectroscopy. Binding of fluorescently labeled soluble protein is observed by optical detection with surface plasmon enhanced fluorescence spectroscopy. By application of the novel assay, we demonstrate that four different oxidized sterol molecules are specifically recognized by the yeast protein Osh5p, a presumed oxysterol binding protein. Osh5p from yeast is the first oxysterol binding protein homologue for which oxysterol binding is shown with this new technique. With the design of our novel in vitro oxysterol binding assay, we have solved the technically challenging difficulty of presenting hydrophobic ligands to hydrophilic proteins in aqueous media.

A significant challenge in materials characterization is the determination of the structure of nanoparticle assemblies that have been deposited on solid substrates, such as Si[O.sub.2]. The best method for obtaining quantitative information about structure, size, and spacing on the nanometer-length scale is TEM; however, commercially available TEM grids offer a limited range of substrate materials. In addition, the compositions of these grids do not permit much chemical processing. Here we describe silicon-based grids with electron-transparent Si[O.sub.2] windows suitable for use as substrates for high-resolution TEM that can be easily fabricated using standard silicon microfabrication techniques. These grids are physically and chemically robust and exhibit the same surface chemistry and chemical stability as an oxide grown on a silicon wafer. Thus, the grids make possible the concurrent investigation of chemical and structural information on the same sample. Convenient modification of the surfaces of the grids provides access to a wide range of new substrates for the direct imaging of chemically modified surfaces by TEM. We demonstrate the utility of these grids by aligning DNA on the chemically modified Si[O.sub.2] surface in order to direct the assembly of linear arrays of nanoparticles. Using these grids, we are able to quantify the effects of assembly conditions on nanoparticle size, spacing, and dispersity in the arrays.

The specificity and affinity characteristics of antibodies make them excellent probes in biosensor applications. Unfortunately, their large size, unstable behavior, and random immobilization properties create numerous problems. The single-domain antigen-binding fragment derived from heavy-chain antibodies of camelids (termed VHH) offers special advantages in terms of size, stability, and ease of generating different antibody constructs. In this study, we show the potential of those VHHs in sensing human prostate-specific antigen (hPSA) by SPR technology. Different VHH constructs were immobilized onto commercial and custom-built sensor surfaces by metal chelation, biotin--streptavidin interaction, or covalent coupling. The detection of subnanogram per milliliter hPSA concentrations could be attained on a covalently coupled three-dimensional dextran surface. Moreover, the ratio of different hPSA isoform concentrations could be assessed via a sandwich assay and resulted in the detection of clinically significant antigen concentrations within 15 min. In addition, for the first time, the intrinsic protein stability is presented as an important probe design factor, since our results reveal that higher intrinsic stability offers higher resistance to harsh regeneration conditions. In conclusion, we present VHHs as a novel class of biosensor probes rivaling conventional antibodies and their derived antibody fragments.

In this work, we report on the surface modification of a micronozzle surface to enhance fluid dispensing in the nanoliter range. Unmodified dispensing chips usually suffer from lateral wetting of the nozzle surfaces by low surface tension liquids resulting in poor control of the volume of the dispensed fluid. Covalent attachment of a fluorinated acrylate polymer to the outer surface of the micronozzle using a novel UV irradiation process helps to overcome capillary and adhesive forces and results in an enhancement of the control on fluid dispensing in the nanoliter range. The modified nozzles have been tested with a variety of fluids having a wide range of surface tensions. The surface modification allows precise control of the dispensing of nanoliter droplets with a high degree of reproducibility.

Adsorbed atoms (adatoms) and vacancies have a significant role to play in the physics of surfaces and the mechanisms of film growth on a substrate. This paper investigates the effect of applied or residual strain on the energetic interaction between pairs of adatoms and vacancies. The analysis is based on a continuum-level point-defect model, where adatoms and vacancies have strain-dependent properties. Atomistic calculations are used to evaluate the defect properties for Si(III). The result is used as input for the defect model in order to investigate the strength and character of the interaction versus strain, separation distance, and relative orientation of the defects. It is found that strain may cause the defects to align in certain direction and modulate their interaction between repulsion and attraction, providing a mechanism for controlled building of nanostructures. [DOI: 10.1115/1.1875392]

The surface chemistry of thiophene on reduced and sulfided Ni/SiO2 and Ni2P/SiO2 catalysts is investigated by using infrared (IR) spectroscopy. The increased reactivity of thiophene on Ni2P/SiO2 catalysts in UHV may explain the high turnover frequency previously reported for Ni2P/SiO2 catalysts relative to sulfided Ni/SiO, Mo/SiO2, and Ni-Mo/SiO2 catalysts.

The study presents the use of single model that can be used as addition of promoter or poison species, which can destabilize the uniform state of surface chemical reactions. It is concluded that interplay between the reaction, interactions, and diffusion of species in this system could result in the development of periodic nonequilibrium spatial patterns.

The study characterizes the different Re-O species formed on O-modified planar and faceted Re surfaces and on a thin-film oxide on Re(1231). On the planar and faceted surfaces the study concluded that methanol reacts via competing pathways of dehydration to CH2O and CO and nonselective decomposition to yield H2 and CO formed by recombinative desorption.

A report on the surface phonon spectrum of the deuterium-terminated D:C(001)-(2*1) surface calculated using a semiempirical total energy approach is presented. The calculated mode energies are found to be in gratifying agreement with recent electron energy loss data and allow identifying the physical origin of the measured features.

Total energy calculations were performed for nitrous oxide and its anion N2O(super -) by Multi Configuration Self-Consistent Field-Configuration Interaction (MCSCF-CI) methods. For the purpose of studying the strong vibrational state dependence of the reaction outcome the study discusses transitions form the adiabatic N2O(super -) [(sub 2) A'] potential energy surface on the (super 2)A'' surface.

The prototypical photoreaction H(sub ad)+H( ad)->H(sub 2.gas) on Ru-(001) initiated by intense near-infrared femtosecond laser excitation is investigated. Detailed results on the influence and coverage dependence of the fs laser-induced hydrogen formation are presented.

It is shown that the loss of species on the reactor wall has to be taken into account while analyzing the kinetic results of the droplet-train apparatus. The uncertainty of the extracted gas-surface reaction and the probability for high water vapor experimental conditions have increased due to the revision of the kinetics for species with a wall loss.

The energy difference between the gauche and trans structures of ethanol is determined at the CCSD(T)/aug-cc-pVTZ level. Five classes of dimer structures exist due to the two monomer conformations. In a systematic way 600 structures were generated as initial structures for the dimer geometry optimization.

A computational kinetic Monte Carlo (KMC) experiments that examines the time scale and pathways of H-atom mobility across the step edges connecting (100), (110), and (111) surfaces and the time-scale and pathway of H-atom penetration in the sublayer of the surfaces is reported. The activation energies for H mobility from site-to-site using a realistic potential energy function are also determined.

The surface structures and segregation of ultrathin polystyrene (PS)

We report fabrication, characterization, and use of microfluidic analysis devices containing surface-immobilized cell-capturing molecules. Amino-terminated biotin ligands are immobilized onto the luminal surface of a microdevice and effectively support serf-assembly of proteins, antibodies, and mammalian cells. For this purpose, chemical vapor deposition (CVD) polymerization is used to functionalize PDMS-made microfluidic devices with poly-[para-xylylene carboxylic acid pentafluorophenolester-copara-xylylene]. The resulting reactive coating shows excellent adhesion when deposited in thin films (~100 nm, and the distribution of the pentafluorophenol ester groups is reasonably uniform within the microchannel inner surface, as examined by fluorescence microscopy. The utility of these devices for cell-based bioassays is demonstrated by monitoring the concentration-dependent effect of the disintegrin echistatin on cell adhesion. The described assay format could be relevant to clinical research in various fields, including angiogenesis research.

Hydration properties of organic and biomolecules are frequently calculated using continuum models. These models are also used to estimate its dependence on conformation and association. Nonpolar solvation contributions are often estimated from the solvent assessable surface of a molecule using a single surface tension parameter.

The potential energy surface for the C(super 3)P(sub j)) + C(sub 3)H(sub 5)(X (super 2)A(sub 1) reaction was investigated using ab initio G2M(MP2)//B3LYP/6-311G** calculations. The results indicate that C((super 3)P(sub j)) can add without a barrier either to the terminal CH(sub 2) group of the allyl radical to form a metastable intermediate INT1 or between two CH(sub 2) groups to produce a bicyclic structure INT2.

A theoretical study of the dynamics of the H + HC1system on the potential energy surface (PES) of Bian and Werner has been presented. State-to-state reaction probabilities for the exchanged and abstraction channels were calculated using a time-dependent wave pocket approach.

A new approach in the manipulation of the size and chemistry of nanoscopic characteristics using contact molding and living free radical polymerization is presented. A focus is also laid on creating templates for pattern replication and the development of process steps for transferring images into molecular electronics applications.

Here we report a design and synthesis of a chemically functional polymer membrane by an interracial polycondensation reaction and multilayer flow inside a microchannel. Single and parallel dual-membrane structures are successfully prepared by using organic/aqueous two-layer flow and organic/aqueous/organic three-layer flow inside the microchannel followed by an interracial polycondensation reaction. By using the inner-channel membrahe, permeation of ammonia species through the innerchannel membrane is successfully achieved. Furthermore, horseradish peroxidase is immobilized on one side of the membrane surface to integrate the chemical transform function onto the inner-channel membrane. Here substrate permeation through the membrane and subsequent chemical transformation at the membrane surface are realized. The polymer membrane prepared inside the microchannel has an important role in ensuring stable contact of different phases such as gas/liquid or liquid/ liquid and the permeation of chemical species through the membrane. Furthermore, membrane surface modification chemistry allows chemical transformation of permeated chemical species. These methods are expected to lead to development of complicated and sophisticated chemical systems involving membrane permeation and chemical reactions.

Raman spectroscopy is used to examine the effects of temperature, surface coverage, nature of the alkylsilane precursor (octadecyltrichlorosilane, methyloctadecyldichlorosilane, or dimethyloctadecylchlorosilane), and surface grafting method (surface or solution polymerized) on alkyl chain conformational order in a series of high-density octadecylsilane stationary phases ranging in surface coverage from 3.09 to 6.45 [micro]mol/[m.sup.2]. Conformational order is assessed using the intensity ratio of the antisymmetric and symmetric v(C[H.sub.2]) modes as well as the frequency at which these Raman bands are observed. Conformational order increases with surface coverage. Temperature-induced surface phase changes are observed between 258 and 343 K for this homologous series of stationary phases that are demonstrated to adhere to the Clapeyron equation for a simple first-order transition. Phase changes are discussed in terms of variation of the molar enthalpy, molar entropy, and molar volume of the stationary phase, all of which depend on surface coverage. For the limited range of systems investigated, a correlation between stationary-phase preparation (surface versus solution polymerized and nature of the silane precursor) and extent of alkyl chain order is not clearly observed. Instead, alkyl chain order is largely dependent on bonding density. A molecular picture of temperature-induced disorder in octadecylsilane stationary phases is proposed, with disorder originating at the distal carbon and propagating toward the proximal carbon.

In this paper, we report the effects of different etchants on the mobility-lifetime product ([mu][tau]) of cadmium zinc telluride (CZT). The [mu][tau] values were obtained via Hecht relation. The effects of surface recombination were also investigated using photoconductivity measurements. Results were obtained for a {111} oriented CZT single crystal. We find that the surfaces behave differently after etching. Values for surface recombination rates for (111)A and (111)B surfaces can vary by up to two orders of magnitudes for the same etchant. This large variation in surface recombination rates affects the charge collection efficiency and detector performance. We report surface treatments that enhance the charge collection efficiency for (111)A and (111)B surfaces. Data describing the detector response for [Am.sup.241] Spectra current-voltage relationship, and bulk [mu][tau] values and surface recombination rates are shown for different etchants. Index Terms--CZT, charge collection, nuclear radiation detectors, surface recombination.

Aging of polymeric and composite materials is reviewed mainly from the standpoint of their interfacial performance. Insulating materials can be divided into simple polymers and composites. Polymers for power cables, transformers, insulators and rotating machines consist of thermoplastics such as PE, PET and PPS, elastomers such as silicone, EPR and EPDM, and thermosets such as epoxy. Composites for GIS, rotating machines and insulators comprise epoxy/ glass, epoxy/silica/alumina, and epoxy/mica systems. Aging processes are complicated in general, and take place under simultaneous multiple stresses such as electrical, thermal, mechanical and environmental stresses. Some of the phenomena covered in this paper are associated with the degradation by tracking and erosion and the loss of hydrophobicity in case of surface properties, and with PD, electrical treeing, water treeing and combined phenomena. The quality of cable insulation such as XLPE has been improved extensively from the standpoint of design electric strength. Interfacial problems will emerge for modification of cable joints. It is expected that polymers for outdoor use and filled epoxy resin systems should be improved from their environmental stability and from their design stress enhancement, respectively.

Hydrocarbon oligomers, high-molecular-weight polymers, and polymer additives have been covered with 2--60 nmol of gold/[cm.sup.2] in order to enhance the ionization efficiency for static secondary ion mass spectrometry (s-SIMS) measurements. Au-cationized molecules (up to ~3000 Da) and fragments (up to the trimer) are observed in the positive mass spectra of metallized polystyrene (PS) oligomer films. Beyond 3000 Da, the entanglement of polymer chains prevents the ejection of intact molecules from a 'thick' organic film. This mass limit can be overcome by embedding the polymer chains in a low-molecular-weight matrix. The diffusion of organic molecules over the metal surfaces is also demonstrated for short PS oligomers. In the case of high-molecular-weight polymers(polyethylene, polypropylene, PS) and polymer additives (Irganox 1010, Irgafos 168), the metallization procedure induces a dramatic increase of the fingerprint fragment ion yields as well as the formation of new Au-cationized species that can be used for chemical diagnostics. In comparison with the deposition of submonolayers of organic molecules on metallic surfaces, metal evaporation onto organic samples provides a comparable sensitivity enhancement. The distinct advantage of the metal evaporation procedure is that it can be used for any kind of organic sample, irrespective of thickness, opening new perspectives for 'real world' sample analysis and chemical imaging by s-SIMS.

Research points out that deamidation of glutamine and asparagine residues in the reduced gammaS-crystallin alters the surface charge and causes conformational changes in the protein leading to disulfide bonds formation, which, in turn renders gammaS-crystallin insoluble. Data reveal that this water-insoluble high molecular weight protein contributes to human nuclear cataracts.

A simple genetic algorithm can efficiently search the space of surface-charge distributions in proteins and can find many stabilizing distributions under specified restrictions. It is shown that the genetic algorithm can be employed to select small sets of interacting sites to be used in vitro-directed evolution procedures.

Research describes the syntheses and photophysical characterization of four Ru(sup)II-polypyridyl compounds containing tripodal ligands. Data indicate that the Ru centers are between 15-17 angstroms from the surface and are attached via an incompletely conjugated bridge, which facilitates unchanged redox and steady-state optical properties upon attachment of nanoparticles.

The site-selective assembly of colloidal polymer particles onto laterally patterned silane layers was studied as a model system for the object assembly process at mesoscale dimensions. The structured silane monolayers on silicon oxide substrates were fabricated by a combination of liquid- and gas-phase deposition of different trialkoxysilanes with a photolithographic patterning technique. By using this method various types of surface functionalizations such as regions with amino functions next to areas of the bare silica surface or positively charged regions of a quaternary ammonium silane surrounded by a hydrophobic octadecylsilane film could be obtained. Furthermore, a triethoxysilane with a photoprotected amino group was synthesized, which allowed direct photopatterning after monolayer preparation, leading to free [NH.sub.2] groups at the irradiated regions. The different silane monolayer patterns were used to study the surface assembly behavior of carboxylated methacrylate particles by optical and scanning electron microscopy. In dependence of the assembly conditions (different surface functionalizations, pH, and drying conditions), a selective preference of the particles for a specific surface type versus others was found. Site-specific colloid adsorption could be observed also on the photosensitive silane layers after local deprotection with light. From the photosensitive silane and positively charged ammonium silane, molecularly mixed monolayers were prepared, which allowed particle adsorption and photoactivation within the same monolayer as shown by fluorescence labeling.

Results show that the two genes srtA and srtB code for sortase enzymes, involved in anchoring the proteins to the cell wall. Data indicate that srtA-derived protein links proteins containing an LPXTG moiff to the cell wall, whereas the srtB gene inactivation affects the surface loalization of proteins.

The electronic structure and energies of Au atoms adsorbed on an atomic cluster of kaolinite were calculated using the self-consistent-field Discrete Variational (DV) method. A hexagonal ring of Si[O.sub.4] tetrahedra and three Al[O.sub.2][(OH).sub.4] octahedra, comprising 38 atoms, was used to model the kaolinite crystal flake. An Au atom was used to model the submicrometer Au. Calculations were performed with Au atoms adsorbed at different sites. The systems with lower total energy are those with Au adsorbed on the edge surfaces. The adsorption of Au atoms on the edges is more stable than Au atoms adsorbed on the basal plane. Bond order calculations suggest that significant shifting of atomic charge and overlap of electron clouds between Au and the surface atoms of kaolinite takes place in the systems with Au adsorbed on the edges, especially at sites near Al octahedra.

A study of accurate single-valued double many-body expansion (DMBE) potential energy surface for the ground electronic state of HSO based on novel MR CISD ab initio energies suitably corrected for the complete one-electron basis-set/complete CI limit is presented. A n-body distributed polynomial approach, which implies using individual multinomial developments at the various stationary points is suggested.

A detailed investigation of the complex potential energy surface for the reaction of singlet methylene (CH2) with Nitrous oxide (N2O) using B3LYP/6-31G(d,p) and single point QCISD(T)/6-311G(d,p) methods is presented. This work can assist experiments to identify the products of the CH2+NO2 reaction.

The experiment shows that N2 chemisorbs at 88K on two stepped platinum surfaces, Pt(335) and Pt(779), with exclusive occupancy of step sites. An irreversible conversion from 2-D and 1-D precursor motion occurs as terrace-bound precursors irreversibly convert to step-bound precursors.