Additional Surface Layer Research Articles

TiO2-Based Mortars for Rendering Building Envelopes: A Review of the Surface Finishing for Sustainability

Building envelopes coated with TiO2-based mortars benefit from depolluting, antibiological and self-cleaning effects. Therefore, photocatalytic renders are allies in the quest for sustainability in the built environment, potentially combatting atmospheric pollution, enhancing durability and reducing maintenance needs. Surface finishing characteristics of the renders influence their photocatalytic efficiency and esthetic and functional properties. In this context, this study reviews the existing literature, focusing on proven surface-affecting parameters, the surface and color of TiO2-based mortars, to explore their impacts on photoactive behavior. The incorporation of TiO2 within an additional surface layer and its mixture into the mortar in bulk were observed for surface roughness. Mainly the addition of TiO2 during casting was identified in colored mortars. Generally, a moderate surface roughness led to better photoactivity; microroughness affected self-cleaning by facilitating dirt deposition. The interaction between the surface roughness and the photocatalytic layer affected the water contact angle, regarding superhydrophilicity or superhydrophobicity. The photoactivity of colored mortars with TiO2 depended on the color and amount of the added pigments, which influenced electron–hole recombination, physically occupied active sites or, on the other hand, led to a higher formation of reactive radicals. Surface finishing can thus be designed to enhance the photoactivity of TiO2-based mortars, which is fundamental for current climate concerns and emphasizes the need for life cycle assessments and environmental protection.

Clutter Effect on a Combination of Microwave Imaging and Target Identification Using Ground-Penetrating Radar

This paper presents an experimental investigation of the effect of clutter on the performance of microwave imaging and target identification using ground-penetrating radar (GPR) for buried objects. Signals collected by the GPR were formed to be B-scan and 3D images to carry out the microwave imaging of buried objects. Poles extracted using the short-time matrix pencil method from a late-time response of the received signal collected at a specific position were exploited to identify buried objects. The experiment was set up by constructing a large box filled with sand where an L-shaped metallic sheet was buried. The GPR was installed along with a 2-dimensional scanner above the box to image and identify the buried metallic sheet. In order to investigate the effect of the clutter on the performance of the GPR-based microwave imaging and target identification, small rocks were arranged on the sand surface, and their density was then varied. The experimental results have shown that clutter density significantly affects the sharpness of the B-scan and 3D images. The rocks result in an additional surface layer in the images. Moreover, the results have also shown that the clutter does not affect the performance of the identification of the buried object. From the results, the poles obtained from the GPR scanning inside and outside the buried object region differed. This confirms that the poles of the buried object should be different from those without the object. The poles of the buried object remain constant, although rocks on the sand surface exist since the clutter affects only the early-time response (not the late-time response). With varying clutter densities, the underlying poles were significantly changed, but this does not affect the identification of the buried object.

Effect of a silicon dioxide diffusion barrier layer and its sublimation on the migration of strontium implanted into SiC

Thin film diffusion barriers are inevitable in nuclear reactors for preventing the release of radioactive waste products. The combination of chemical stable silicon carbide (SiC) and silicon oxide (SiO2) layers has been considered being beneficial, thus, we studied the migration and stability of strontium implanted SiC upon annealing, owing an additional SiO2 surface layer. Our investigations show that annealing at 1100 and 1200 °C retained the Sr atoms in comparison to pure SiC and induced strong strontium segregation at the SiO2/SiC interface and SiO2 surface. However, this enhanced the sublimation of the SiO2 layer, while pure SiO2 layers (i.e., without impurities) showed no sublimation after annealing under the same conditions. On the other hand, higher temperatures at 1300 and 1400 °C, resulted also in significant sublimation of the pure SiO2 layer.

Optical properties and electron characteristics of noble-metal-dielectric oxide nanostructures with covered graphene layer

A comparative study of surface plasmon resonances (SPR) and optical properties of metal/dielectric/graphene multilayer films based on high conductive Ag and Cu metals is presented. For measurements of the generation of surface plasmon polaritons under the resonant condition, we involved the total internal reflection ellipsometry and direct spectroscopic ellipsometry for determining optical properties. SPR was studied in graphene/HfO2/Ag(Cu)/Cr/substrate nano-hetero-structures which contain an additional graphene surface layer for enhancement of their sensing performance. The plasmonic performance of each hybrid nano-hetero-structure is evaluated based on quality factors and propagation length of surface plasmon polaritons. The SPR in the graphene/HfO2/Ag(Cu)/Cr/substrate hybrid nano-hetero-structures demonstrate a strong correlation with the measured macroscopic optical characteristics such as the effective real dielectric function ε1(λ) and optical conductivity σ(λ) and extracted from them effective microscopic parameters: the plasma and relaxation frequencies of free electrons ωP and γ. Our results on graphene/HfO2/Ag(Cu)/Cr/substrate hybrid nano-hetero-structures indicate that the real part of the effective dielectric function ε1(λ) and optical conductivity σ(λ) generally follows effective medium approach and the stronger SPR occurs at higher values of ε1(λSPR), and the ratio of ωP2/γ and lower ones of σ (λSPR). Going forward, it appears that graphene/HfO2/Ag(Cu)/Cr/substrate hybrid nano-hetero-structure designs are more suitable for surface plasmon biomedical sensor applications because they could provide both tunability and low optical loss due to specific electronic properties of graphene.

Influence of vegetation and additional surface layers on the water balance of a reclamation cover with elevated water table

Influence of vegetation and additional surface layers on the water balance of a reclamation cover with elevated water table

SrSnO3 Perovskite post-deposition on Ag-doped TiO2 rutile nanoflower for optoelectronic application

Optoelectronic nanomaterials could be improved through bandgap engineering and surface area enhancement, which involves depositing nanoparticles on their photoactive layer surfaces. The present study investigated silver-doped rutile nanoflower TiO2 with an additional surface layer of perovskite SrSnO3 nanoparticles (rT-NF) using a combination of hydrothermal pre-processing followed by radio frequency (RF) magnetron sputtering. The new structure exhibited expanded visible spectrum light absorption. Increasing SrSnO3 deposition time lowered the energy bandgap from 3.0 eV to 2.89 eV. Furthermore, the electrical impedance approach and current-voltage measurement revealed the material's electrical properties, subsequently supported by structural and surface characterization via XRD, FESEM, AFM, and Raman Spectroscopy. The post-deposition of SrSnO3 perovskite on Ag-doped rT-NF raised rutile crystallinity, enhanced its photo response, and lowered its bandgap and bulk resistivity. The outcomes of this work provided a new route to enhancing standard TiO2 nanoflower photoelectric response via perovskite post-deposition on nanoflower surfaces.

A new thermographic method for determining the thickness of the polymer surface layer in sound-absorbing fibrous composite materials

Sound absorption efficiency of the fibrous composite material could be increased by an additional polymer thin layer deposited on the substrate. In order to control the thickness of the polymer surface layer, a new method based on thermographic measurement is presented. The proposed method is much easier to use and does not need any expensive tools in contrast to the Optical Coherence Tomography (OCT) image analysis. The research results show the prospects of this method in the development of sound-absorbing composites. The acoustic measurements confirmed that in the case of fibrous composite materials of viscose fibres/polylactide with an additional polylactide surface layer, the nature of low frequency sound absorption depends on the thickness of this layer.

A simplified skid resistance predicting model for a freeway network to be used in a pavement management system

ABSTRACT The available skid resistance, or friction, in a pavement surface is a vital parameter for functional evaluations of roads due to its relation with crashes. Therefore, highway administrations must collect friction data on their road network to provide safe roads to users. Additionally, a prediction model that can forecast the available skid resistance in each road segment is necessary for an efficient pavement management system (PMS). The aim of this paper is to develop a skid resistance prediction model for the bituminous pavements of the motorway network of federal state of Bavaria, in Germany, with information that is typically available in a PMS: the Annual Average Daily Traffic , the Annual Average Daily Heavy Traffic , and the number of lanes in each segment. Despite its simplicity, with 6410 road segments of 2 and 3 lanes of the Bavarian motorway network, the model achieves a determination coefficient (R2 ) of 0.405. If information about the surface layer material is added, R2 increases to 0.480. Consequently, apart from predicting the minimum available friction in each lane in a motorway, the study underlines the necessity that a PMS should contain the recommended elements and additional surface layer material, because the quality of the prediction improves.

Evaluation of anti-galling properties of threaded coating of tubing couplings obtained by thermal diffusion galvanizing and friction cladding

The construction and subsequent operation of oil and gas wells is not complete without oil-well tubing. Tough requirements are imposed on threaded joints of oil-well tubing: ensuring the required level of wear resistance during multiple make-up-breakout cycles while maintaining the tightness of the joint. In this work, it is proposed to apply a coating formed by thermal diffusion galvanizing with the application of an additional surface layer of fluoropolymer by cladding with a flexible tool as a dry solid lubricating coating. The resulting coating is non-uniform in thickness (range from 21 to 31 microns). On average, the thickness of the coating on the couplings is significant - from 46 to 61 microns. The main thickness is due to the thermal diffusion coating, the thickness of the polymer layer does not exceed 7 microns. The anti-seize properties of a dry solid lubricating coating have been evaluated. The properties were assessed using a CKR-500 clutch wrapping machine. During the tests, the running-in of the coating was observed: peeling of the coating; the formation of stripes of a dark color with a mirror shine on the tubing couplings; partial transfer of the coating to the nipple end in the form of dark stripes (metal-to-metal seal); partial destruction and transfer of the coating to the places of maximum contacts, which leads to an additional increase in the antiwear properties of the threaded joint (the effect of “self-lubrication”). A significant increase in make-up moments was also observed: the torque was higher than 8000 N·m (instead of the planned 3700 N·m). The heating of the tight threaded joint was recorded (at 4-6 cycles up to 75 °C). The couplings successfully withstood 11 make-up-breakout cycles, after which no significant wear of the coating and the development of microdamages in the multilayer coating was observed. Thus, it is necessary to continue the work on the study of the properties of the coating of the type “thermal diffusion galvanizing + cladding with a flexible tool”.The research was funded by RFBR and Chelyabinsk Region, project No. 20-48-740024\20

УДОСКОНАЛЕННЯ КОНСТРУКЦІЇ ГЛУШНИКІВ ДЛЯ ЗМЕНШЕННЯ РІВНЯ ЗВУКОВОГО ТИСКУ НА ОПЕРАТОРІВ МАЛОГАБАРИТНИХ ТРАКТОРІВ

Noise background, as an important factor in the working conditions of agricultural operators, has a direct impact on human health and productivity. This topic is especially relevant for small tractors, which in most cases are not equipped with cabs. One of the main means of reducing the sound pressure on the operator are the mufflers of exhaust gases, which mainly have a labyrinth-absorbing type of action. The paper proposes a fundamental approach to the design of the muffler by the criterion of reflection and scattering of sound waves with the verification of efficiency by computer simulation. The purpose of research: - to improve the working conditions of operators of small tractors that are not equipped with cabs, by reducing the sound pressure level from internal combustion engines; - to improve the noise-absorbing properties of mufflers of exhaust gases of engines with observance of requirements to manufacturability of process of their manufacturing; - to develop a structural scheme of the exhaust gases muffler based on the results of preliminary modeling and analysis of the trajectory of the gas flow in the cavity of its working part. Methods. Determination of the sound pressure level of the engine of a small tractor by mathematical (computer) modeling of the behavior of the exhaust gas flow in the muffler cavity in different frequency ranges. Results. The article analyzes the main sources of noise during the operation of agricultural machinery with internal combustion engines (ICE). On the basis of literature sources and methods, their separate degree of influence on the complex picture of noise pollution of the working space of the operator of a small tractor is established. A comparative analysis of the efficiency of mufflers, created on the generally accepted principles and approaches to the design of such devices. According to the results of previous tests, shortcomings and limitations in the application of design concepts were identified, an additional analysis of external causes and factors was made, and adjustments were made to the method of creating muffler designs. An alternative design approach to the creation of internal combustion engine mufflers of small tractors is proposed and computer modeling of the processes of sound pressure distribution and sound waves in their cavity is performed. Conclusions. 1. A layout diagram of the design of the exhaust muffler, containing a resonator chamber and a shell module, which is made in the form of a three-stage ribbed diffuser of oscillations of the exhaust flow pulses with an additional surface layer of the vibration absorber. The parameters of the exhaust flow of exhaust gases of a typical diesel engine of a small tractor with a capacity of 24 hp are calculated. (pressure - 11652 Pa, acceleration – 90-105 m / s2, frequency - 1950-3300 Hz), which performed computer simulations of the process of gas movement in the muffler cavity of the proposed layout. Optimal design parameters were selected to ensure the maximum possible noise absorption with a body diameter of 150 mm and a length of 600 mm. The calculated sound pressure when working at the crankshaft speed (1700-2000) rpm does not exceed 72 dB. At the same time, the design of the muffler is made in compliance with the requirements for economic feasibility, manufacturability and in accordance with the capabilities of industrial production. A further direction of research is the manufacture of an experimental sample of the muffler and testing for the efficiency of its noise absorption in the conditions of operation of small tractors.

Retrieving Leaf Chlorophyll Content by Incorporating Variable Leaf Surface Reflectance in the PROSPECT Model

Leaf chlorophyll content plays a vital role in plant photosynthesis. The PROSPECT model has been widely used for retrieving leaf chlorophyll content from remote sensing data over various plant species. However, despite wide variations in leaf surface reflectance across different plant species and environmental conditions, leaf surface reflectance is assumed to be the same for different leaves in the PROSPECT model. This work extends the PROSPECT model by taking into account the variation of leaf surface reflection. In the modified model named PROSPECT-Rsurf, an additional surface layer with a variable refractive index is bounded on the N elementary layers. Leaf surface reflectance (Rs) is characterized by the difference between the refractive indices of leaf surface and interior layers. The specific absorption coefficients of the leaf total chlorophyll and carotenoids were recalibrated using a cross-calibration method and the refractive indices of leaf surface and interior layers were obtained during model inversion. Chlorophyll content (Cab) retrieval and spectral reconstruction in the visible spectral region (VIS, 400–750 nm) were greatly improved using PROSPECT-Rsurf, especially for leaves covered by heavy wax or hard cuticles that lead to high surface reflectance. The root mean square error (RMSE) of chlorophyll estimates decreased from 11.1 µg/cm2 to 8.9 µg/cm2 and the Pearson’s correlation coefficient (r) increased from 0.81 to 0.88 (p < 0.01) for broadleaf samples in validation, compared to PROSPECT-5. For needle leaves, r increased from 0.71 to 0.89 (p < 0.01), but systematic overestimation of Cab was found due to the edge effects of needles. After incorporating the edge effects in PROSPECT-Rsurf, the overestimation of Cab was alleviated and its estimation was improved for needle leaves. This study explores the influence of leaf surface reflectance on Cab estimation at the leaf level. By coupling PROSPECT-Rsurf with canopy models, the influence of leaf surface reflectance on canopy reflectance and therefore canopy chlorophyll content retrieval can be investigated across different spatial and temporal scales.

Mapping Strain and Composition Effects on Gesn Band Structure Using Spectroscopic Ellipsometry

One of the most interesting research areas in silicon photonics has been the development of silicon-compatible electro-optical devices including detectors, modulators, and light sources, to name a few. IN this regard, the binary alloy Ge1-xSn x has been of particular importance due its bandgap directness in contrast to silicon and germanium.[1-2] As a matter of fact, great efforts have been expended in recent years towards the development of the epitaxial growth of high-quality GeSn crystals on silicon platform and their introduction in design and fabrication of optoelectronic devices.[3] This interest has been nurtured by the ability to manipulate the GeSn band structure by controlling Sn composition and strain. These two degrees of freedom provide flexibility to tune the optoelectronic properties relevant to a variety of devices. For instance, GeSn is attractive material system for photodetectors with absorption edge extending over a broad wavelength range from the short wavelength infrared (SWIR, 1.6-2 µm) to the mid-infrared (MIR, 2-5 µm). In this perspective, this work reports detailed investigations of the influence of both strain and composition on the band structure above 1 eV of GeSn ternary alloys through a spectroscopic ellipsometry study. Understanding the individual influence of each parameter is highly critical to establish and optimize the properties of GeSn device layers. GeSn thin films investigated in this work were grown using a low-pressure Chemical Vapor Deposition (LP-CVD) at different Sn compositions in the 7-18 at.% range.[4] A graded growth process on Ge-virtual substrates was used. Figure A shows a typical example of the investigated samples. The figure exhibits a schematic representation where the bottom layer (BL- 6.3% of Sn) and the top layer (TL- 12.5% of Sn) have different Sn composition. Furthermore, High-Resolution X-Ray Diffraction (HR-XRD) was used to characterize the compressive strain present in each layer. In the sample shown in Figure A, the strain was found to be respectively equal to -0.65% and -1.503%, for the BL and TL. Next, a rotating-analyzer spectroscopic ellipsometry system measures the following parameters (Ψ and Δ) for different incidence angles from 45 to 70° as shown in Figure B. These parameters are then coupled with an optical model to allow for an accurate determination of the complex dielectric (ε=ε1+iε2) of the sample. The developed optical model is presented in Figure A where the different constituting layers are shown: GeSn(BL/ML)/ Ge(VS)/Si. Furthermore, two additional surface layers were introduced to simulate the surface roughness as well as the presence of the native GeO2 oxide. The optical properties of the GeO2 oxide were used in their tabulated form from Reference [5]. The optical model is shown as a dashed line in Figure B, and the accuracy is measured by a very low MSE of 0.598. Consequently, the dielectric constant can be extracted. Having extracted the dielectric constant from the ellipsometry measurement, it becomes now possible to quantify the contributions from the E1, E1 + Δ1, E0’, E2, and E1’ critical points in the joint density of electronic states which they will be enhanced by computing numerical second derivatives of the already measured dielectric function. The numerical second derivative is often coupled with the Savitsky-Golay smoothing filter to reduce noise while maintaining the shape and the height of waveform peaks. The resulting lineshapes were fitted with model expressions from which the critical point energies Ej, amplitudes, broadenings Aj, and phases ϕj were determined. The model lineshapes have been well established in literature. [6] In Figure C, a lineshape fit for the E2 critical point energy for the Bottom layer (BL) was undertaken. The accuracy of the fit was confirmed with a coefficient of determination (R2) higher than 0.97. The Levenberg-Marquardt fit gave an E2 energy of 4.06±0.20 eV for the BL, whereas for the Top layer (TL), E2 was equal to 4.10±0.30 eV. After finding the energy for each sample, it becomes possible to map the effect of strain on the bang gap energies. Based on these systematic studies, this presentation will describe the individual influence of strain and composition on the optical properties of Sn-rich GeSn semiconductors.

Amorphophallus: New insights into pollen morphology and the chemical nature of the pollen wall

In pollen characters, Amorphophallus is one of the most diverse genera in the Araceae. The present work is a critical survey of contradicting reports on the impact of acetolysis treatment on Amorphophallus pollen, on the chemical nature of the outer pollen wall layer and of electron-dense (dark) granules found within it. Furthermore, we wanted to clarify the pollen polarity and to test conclusions based on different preparation techniques. Pollen morphology of 25 species is investigated by light microscopy, scanning electron microscopy and transmission electron microscopy. Our results show that Amorphophallus pollen is not resistant to acetolysis treatment. The use of different transmission electron microscopy staining methods proved the polysaccharide nature of the outer pollen wall layer and of the granules within it. Moreover, an additional thin surface layer was found in all investigated species. Microspores in early and late tetrad stages show that the less convex side of the microspore is the proximal face and the more convex side the distal face. The extrusion of pollen in strands is illustrated for the first time by light microscopy and scanning electron microscopy. Furthermore, observations of pollen in water showed that in some of the investigated species the pollen wall is shed immediately before pollen tube formation.

Photoemission Study on the Interaction Between LiCoO2 Thin Films and Adsorbed Water

Surface layers at the cathode-electrolyte interface strongly affect the performance of the Li-ion cell. Such surface layers are found during manufacturing and operation of the battery. As water can never be fully excluded from the manufacturing chain, it will form an additional surface layer situated between cathode and electrolyte. In this contribution, we investigate the interaction between the LiCoO2 electrode and H2O by a surface science approach. H2O was adsorbed stepwise onto a LiCoO2 thin film, and intermediate X-ray photoelectron spectroscopy analysis was performed after every step. Adsorption results in the formation of a Li2O/LiOH-type reaction layer on top of the electrode and downward band bending attributed to a Li+-ion transfer out of the electrode.

One-Step Synthesis of Novel Mesoporous Three-Dimensional GeO2 and Its Lithium Storage Properties

In order to meet the requirements of high energy density as well as high power performance, a worldwide effort has been made to develop novel high-performance electrode materials to keep pace with the fast increasing market demands. Various compounds that form intermetallic phases (so-called “alloys”) with lithium have been proposed as alternative anode materials, such as silicon (Si) [1-2], tin (Sn) [3] and germanium (Ge) [4]. Compared to Si, less attention has been paid so far on Ge due to its higher costs. Nevertheless, its good lithium diffusivity (400 times higher than in silicon) and high electronic conductivity (ca. 104 times higher than silicon) enable it as a promising anode material for the next-generation LIBs. Currently, researchers report on different structures of Ge-based materials, such as nanotubes [5], nanowires [6], porous structures [7] and Ge-based composite materials [4]. So far, only a few studies focus on GeO2 as anode material. GeO2 is of interest for application as negative electrode material due to its high theoretical reversible capacity (1125 mAh g-1 based on 4.25 mol Li per mol Ge), low operation voltage (0.7 V to 0 V vs. Li/Li+) and higher thermal stability compared to Ge.[8] The reaction of GeO2 with Li involves two steps: 1) GeO2 + 4Li à Ge + 2Li2O; 2) xLi + Ge ⇌ LixGe (x ≤ 4.25). While the first reaction can be considered as to a large part electrochemically irreversible, resulting in a large irreversible charge loss by formation of Li2O, the lithiation/de-lithiation reaction in step 2) can be regarded as reversible, providing the discharge capacity of GeO2. The high irreversible capacity during the first lithiation process is also well-known for SnO2-based anodes and is one of the main reasons hindering so far the application in commercial lithium-ion batteries.[9] In general, the synthesis of GeO2 can be achieved by different methods, including hydrolysis reactions from a Ge precursor, chemical vapor deposition (CVD) and sputter processes. In this work, novel mesoporous three-dimensional GeO2 was successfully synthesized by a facile one-step synthesis method followed by mixing with graphene using a spray drying process. The as-prepared GeO2 shows a bean-like morphology with a particle size of 400 to 500 nm in length and 200 to 300 nm in diameter (Figure 1a-d). In a further step, we take the advantages of graphene (low-dimensional carbon material with high electronic conductivity; excellent mechanical properties; graphene can contribute to the capacity) to further enhance the electrochemical performance of b-GeO2. As illustrated in Figure 2, it can be clearly observed that the GeO2 particles are tightly anchored on or wrapped within the graphene sheets. Notably, during the mixing process, GeO2 particles are still homogenously dispersed within or firmly encapsulated by the graphene sheets. The b-GeO2 without any additional conductive surface layer shows a high reversible capacity for lithium storage of 845 mAh g-1 after 100 cycles, with nearly no capacity fading. When graphene was employed to be mixed with GeO2 via a spray drying method, the electrochemical performance is further significantly improved. The b-GeO2/graphene composite electrode gives a higher de-lithiation capacity of 1,021 mAh g-1 for 200 cycles at 0.2C and a high rate capability of up to 5C. This superior electrochemical performance benefits from its uniformly dispersed mesoporous structure, in which the GeO2 particles are homogeneously distributed on or within the conductive graphene sheets. Figure 1. Low-resolution (a, b) and high-resolution-resolution (c, d) SEM images of b GeO2. Figure 2. (a, b) SEM images of the b-GeO2/graphene composite prepared by spray drying method.

Abstract 4459: Characterization of a novel magnetic nanoparticles formulation for cancer therapeutic applications

Abstract We have successfully engineered a magnetic nanoparticles (MAG-NPs) formulation using a multi-layer approach which can be used for drug/gene/biomolecule delivery, hyperthermia, and magnetic resonance imaging (MRI) applications in cancer therapeutics. Overcoming nanoparticles clearance by the immune system remains a major challenge. This formulation is designed to provide an additional surface layer as molecular “authentication” that the body does not recognize as foreign material. The interaction between the surface of nanoparticles and plasma proteins leads to nanoparticle-protein complex which determines the rational design of clinically useful formulations for cancer therapeutics. This formulation was very effective for inhibiting tumorigenic features in in vitro and in vivo cancer models. Therefore, we further studied our MAG-NPs formulation for biologically and clinically relevant characteristic features for its clinical translation. For this, we have examined the change in particle size, zeta potential, human serum protein adsorption, hemotoxicity, uptake, targeting cancer cells, and magnetic resonance imaging of the MAG-NPs formulation. No significant change was observed in particle size and zeta potential of nanoformulation with the incubation of 0.5 to 50 wt/wt% human serum. With increase of serum concentration and particle concentration there was a clear indication that apart from serum albumin and transferrin; apolipoprotein E (Apo-E, a surrogate marker for improved circulation of nanoparticles and enhanced crossing of the blood-brain barrier) also adsorbed on the surface of nanoparticles (determined by Western blot analysis). No significant primary or secondary structural alterations were observed in serum proteins through circular dichroism study. Hemolysis assay demonstrated almost no hemolysis at the tested concentrations (up to 1 mg/mL) for nanoparticles compared to the positive control (sodium dodecyl sulphate). Particle internalization and targeting cancer cells were observed in dose dependent manner and were not influenced by protein architecture on surface of nanoparticles. Additionally, this formulation has exhibited identical T1 relaxation times (∼1.1-1.6 s) and T2 relaxation times (∼ 13-14 ms) which suggests that our nanoparticles retained MRI properties even after serum proteins adsorption and drug/biomolecular encapsulation. Based on all these superior clinical characteristics, this MAG-NPs formulation can effectively be used for the delivery of drug/siRNA/miRNAs for cancer therapy, diagnosis, and imaging. Citation Format: Murali M. Yallapu, Neeraj Chauhan, Shadi F. Othman, Vahid Khalilzad-Sharghi, Meena Jaggi, Subhash C. Chauhan. Characterization of a novel magnetic nanoparticles formulation for cancer therapeutic applications. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4459. doi:10.1158/1538-7445.AM2014-4459

Nonthermal graphitization of diamond induced by a femtosecond x-ray laser pulse

Diamond irradiated with an ultrashort intense laser pulse in the regime of photon energies from soft up to hard x rays can undergo a phase transition to graphite. This transition is induced by an excitation of electrons from the valence band or from atomic deep shells of the material into its conduction band, which is followed by a transient rapid change of the interatomic potential. Such a nonthermal phase transition occurs on a femtosecond time scale, shortly after or even during the laser pulse. In this work we show that the duration of the graphitization depends on the incoming photon energy: the higher the photon energy is, the longer the secondary electron cascading which promotes the electrons into the conduction band will take. The transient kinetics of the electronic and atomic processes during the graphitization is analyzed in detail. The damage threshold fluence is calculated in the broad photon energy range and is found to be always $\ensuremath{\sim}$0.7 eV/atom in terms of the average dose absorbed per atom. It is confirmed that the temporal characteristics of a femtosecond laser pulse (at a fixed pulse duration and fluence) do not significantly influence the transient damage kinetics. Finally, the influence of an additional surface layer of high-$Z$ material on the damage within diamond is discussed.

Ferroelectric surface chemistry: First-principles study of the PbTiO3surface

Ferroelectric surfaces provide a promising method for modifying surface reactions via an external electric field, which can potentially provide an avenue for tunable molecular binding and surface catalysis. Using first-principles density functional theory, we investigate how the properties of the PbTiO${}_{3}$ surface vary with polarization and how these changes affect CO${}_{2}$ and H${}_{2}$O adsorption. We find that the polarized stoichiometric surfaces cancel the depolarizing field with an electronic reconstruction, which has a large effect on molecular binding energies. However, thermodynamically, the system will instead cancel the depolarizing field by adjusting the surface stoichiometry. Variation of the polarization and the environmental conditions can thus be used to systematically tune the surface chemistry over a wide range. In addition, we consider the addition of several different catalytic monolayers to the PbTiO${}_{3}$ surface, and we find that additional surface layers can be used to modify the binding of molecules to the surface while still responding to the polarization of the substrate.

Analysis of surface acoustic wave propagation in a two-dimensional phononic crystal

In this paper, we present a numerical technique to calculate the surface acoustic wave (SAW) in a two-dimensional phononic crystal (PC). By the technique, the SAW in the system, which is obtained by adding an additional composite surface layer on the xy-cut surface of a two-dimensional PC, is investigated. Result shows that the behavior of SAW in the studied system is mainly determined by the residual penetration depth of the SAW into the PC structure. Based on this understanding, we show that the SAW in the band gap of the PC can be controlled efficiently by changing the structure of the surface layer.

Probing adsorption of sodium poly(acrylate) at the calcite–water interface by ellipsometry

Null ellipsometry was used to investigate the adsorption of poly(acrylic acid) (PAA) in the form of sodium poly(acrylate) (NaPA) on polished calcite crystals in aqueous electrolytes at pH 9. The ellipsometric angles were converted into adsorbed mass with an optical layer model, which treats the surface roughness by introducing an additional surface layer. One finds that the adsorbed mass saturates near 4 mg/m 2. Higher values of specific adsorbed mass were also observed, and they can be explained with the precipitation of polyelectrolyte with calcium ions.