Big Spheres Research Articles

Bandgap mechanisms and wave characteristics analysis of a three-dimensional elastic metastructure

PurposeIn order to investigate the vibration reduction properties of a three-dimensional elastic metastructure with spherical cavities at low frequencies.Design/methodology/approachThe bandgap characteristics of a three-dimensional elastic metastructure with spherical cavities are studied based on analytical and numerical approaches.FindingsThe results of both method revealed that the vibration of the vertexes masses is important for opening bandgaps. The fact that the big sphere cavity radius or short side length of the cube unit leads to a wider bandgap, is noteworthy.Originality/valueThis research provides theoretical guidance for realizing the vibration attenuation application of EMs in practical engineering.

Energy window optimization for Bremsstrahlung Y90 SPECT-CT imaging : a phantom study

Introduction: In Yttrium-90 SPECT imaging, the energy window and collimator used during acquisition can have a major effect on image quality. In this work, we used a new and independent method to verify the prevoius results suggest different energy ranges, but all centered at 130 keV. Materials and method: We used Siemens Symbia SPECT-CT system fitted with High Energy General Purpose (HEGP), Medium Energy General Purpose (MEGP) and Low Energy High Resolution (LEHR) to acquire data from NEMA IEC PET Body Phantom with its 6 different spheres of 3.7, 2.8, 2.2, 1.7, 1.3, 1.0 cm diameter. Results:HEGP collimator is the most suitable for acquisitions of 90Y bremsstrahlung radiation from the point of view of the correct volume reproduction. For the bigger sphere’s study, the optimum ISO-counting curves is related to the energy range centred in 130 keV.Conclusion: The results obtained are consistent with previous studies. The Iso Counting Curves method can help to improve image quality.

Items and proposals related to the suburban area-planning within the big city sphere of influence

The paper is dedicated to the major aspects of formation and functioning of the suburban areas within the big city sphere of influence. A set of questions was determined to be studied, in particular, definition of essence of the concept of “suburban area”, definitions of suburban area. The new trend of territorial development is the processes of population decentering from the central districts per city, which is related to the factors of development of the objects of social and economic support of the population, as well as a number of environmental problems. The paper proposes a model of suburban area territory planning within the big city sphere of influence, which allows managing and using territories of suburban area a more efficient way.

Comment to “Skeletonization-based beam finite element models for stochastic bicontinuous materials: Application to simulations of nanoporous gold” by C. Soyarslan et al. [J. Mater. Res. 33(20), 3371 (2018)

Abstract

Concealed Information About The Future In The Qur’an: The Examples of al-Isra 17/79, ar-Rum 30/1-5 and al-Fath 48/27

Kur’ân’ın cümle yapısında ihbârî ve inşâî olmak üzere iki temel ifade biçimi görülmektedir. Dil otoritelerine göre bu ifade biçimleri nihâî ayrımları ifade etmemekte, zaman zaman birinin bir diğerinin kapsamına dahil olabileceği geçişkenlikleri içinde barındırmaktadır. Süreç içerisinde bu geçişkenlikler göz ardı edilmiş, bunun neticesinde gayb, Kur’ânî bir problem haline getirilmiştir. Bu problemin çözümü için üretilen gayb tasnifleri müşterek bir kanaat oluşturamamış, üstelik vahiy ve Allah tasavvurunda sorunlara yol açmıştır. Çoğu zaman ayetlerdeki üslûp dikkate alınmamış, lafızlardaki gelecek kipleri ve tekidli ifadeler Kur’ân’ın ilahîliğinin ve Rasul’ün risaletinin delili sayılmış, bu durum ilerleyen süreçte İ‘câzu’l-Kur'ân başlıklarının argümanı haline gelmiştir. Bu çalışmada Allah’ın geleceğe dair bilgisi konusuna girilmeden geleceğe yönelik bilgi taşıdığı düşünülen üç ayetin cümle türü üzerinden gaybla ilişkisi ele alınmıştır. Kur’ân’ın gayba ayırdığı yer, birçok yerde aslî bir zeminde değil, muhataplarının gayba ve gaybî bilgi kaynaklarına dair yanlış anlayışlarına cevap üretme zeminindedir. Bu anlamda çalışmamız, gayba dair ihbârî ifadelerin üst formu inşâî bir yapıdan müteşekkil çoğu zaman teselli, teşvik, cesaretlendirme içerikli Kur’ânî bir üslûbun eseri olduğunu temellendirmektedir. Haber formunda fakat inşa nitelikli bu ayetlerin vukuu ise, mucizevî sonuçlar değil, kişilerin kevnî yasalara uygun doğru eylem ve tutumlarının doğurduğu sonuçlardır. Bu anlamda ayetler, nihai olarak bir başarının gerçekleşeceğine işaret etmemekte, “dirayetli olan, sebat gösteren aydınlığa çıkar” minvalinde bir mesajla Allah’ın yaratılış üzerindeki sünnetine vurgu yapmaktadır.

Fabrication and photocatalytic properties of porous ZnO architectures

In this work, a series of porous zinc oxide (ZnO) architectures were prepared by changing the concentration of trisodium citrate by using a green hydrothermal and calcination method, and the photocatalytic performance of the ZnO samples were investigated by using Rhodamine B as degradant under ultraviolet irradiation. The concentration of trisodium citrate had a great influence on the morphology, structure and optical properties of the ZnO samples, which together affected the photocatalytic activity. With the increase of trisodium citrate concentration, the morphology of as-prepared hexagonal wurtzite ZnO changed from flower-like to porous microsphere, and then formed bigger spheres which were more tightly assembled by nanosheets. The higher photocatalytic performance of ZnO microsphere prepared from 1 × 10 -3 mol·l -1 trisodium citrate solution was due to the hierarchical pore structure, its better ultraviolet light absorption and higher charge separation. Moreover, the mechanism of the dye photodegradation reaction was discussed.

Intermediate state in a type-I superconducting sphere: pinning and size effect

Simulations based on the time-dependent Ginzburg–Landau equations show that the magnetization and spatial structure of the intermediate state are strongly affected by both the radius of the sphere and by the concentration of pinning centers. The intermediate state undergoes a transformation from a one-domain structure for a small sphere to a multi-domain structure in big spheres. In spheres where part of the superconducting material is replaced by the 0.5% randomly distributed normal phase (dirty case), the intermediate state demonstrates a pronounced turbulence behavior.

Intruders in disguise: Mimicry effect in granular gases

In general, the total kinetic energy in a multicomponent granular gas of inelastic and rough hard spheres is unequally partitioned among the different degrees of freedom. On the other hand, partial energy equipartition can be reached, in principle, under appropriate combinations of the mechanical parameters of the system. Assuming common values of the coefficients of restitution, we use kinetic-theory tools to determine the conditions under which the components of a granular mixture in the homogeneous cooling state have the same translational and rotational temperatures as those of a one-component granular gas (“mimicry” effect). Given the values of the concentrations and the size ratios, the mimicry effect requires the mass ratios to take specific values, the smaller spheres having a larger particle mass density than the bigger spheres. The theoretical predictions for the case of an impurity immersed in a host granular gas are compared against both direct simulation Monte Carlo and molecular dynamics simulations with a good agreement.

Efficient Electron Transport Scaffold Made up of Submicron TiO2 Spheres for High-Performance Hole-Transport Material Free Perovskite Solar Cells

Nanoporous submicron TiO2 spheres of diameters around 200 nm are synthesized by a hydrothermal process and used as a scaffold layer for improving light absorption, charge transportation, as well as photovoltaic performance in hole-transport-layer free perovskite solar cells employing carbon counter electrodes. The TiO2 submicron spheres show a porous feature with high specific surface area, which is essential for perovskite infiltration, charge extraction, and transportation in mesoscopic perovskite solar cells. Furthermore, big spheres exhibit better light scattering property compared to traditional TiO2 nanoparticles, thus enhancing light absorption in corresponding devices. The present perovskite solar cells employ a TiO2 scaffold layer of optimized thickness of about 600 nm and show an average power conversion efficiency of 13.46 ± 0.41%, which is 18.4% higher than that of counterparts based on TiO2 nanoparticle (11.37 ± 0.40%). The champion cell exhibits an impressive efficiency of 14.3%, which is very competitive in perovskite solar cells without a hole transport layer using a carbon electrode. Moreover, our carbon based perovskite solar cell shows excellent long-term stability against moisture and heat with negligible degradation for 210 days of storage under ambient conditions.

Theory and calculation of colloidal depletion interaction

Colloidal dispersion is composed of particles with size ranging from 1 nm to [Formula: see text]m dispersed in solvents. There are the volume exclusion interaction and other interactions between colloidal particles, of which the former interaction causes the depletion effect. When a big sphere is immersed in the colloidal system of small spheres, there is a depletion layer around the big sphere where the center of small sphere cannot enter. The depletion layers of two big spheres overlap if they are close to each other, increasing the free volume accessed by small spheres and thereby enlarging the entropy of the system. As a result, an effective interaction between the two big spheres is resulted from the change of entropy as a function of their distance, which is referred to as the depletion interaction. This paper first introduces the concept and scenario of the depletion interaction in colloidal systems. Then we briefly introduce various numerical or simulations methods of the depletion interaction of hard sphere systems, such as the acceptance ratio method, Wang–Landau method, and the density functional theory method. Taking the Asakura–Oosawa model as an example, we introduce a useful approximation method, Derjaguin approximation as well as the derivation of some approximate formula for the depletion interaction of different hardcore colloidal systems, such as between a pair of spheres in mono-disperse small spheres, between a hard sphere and a hard wall in a liquid of small spheres, and between a pair of hard spheres in a liquid of thin rods and thin disks.

Effect of Initial Size and Shape Importance on Masse Transfer during Convective Drying

In this paper the influence of sample initial size on their convective drying at 80°C using convective dryer is determined. Results prove that initial size must be taken into account when drying process was estimated. This influence is limited by its form of cut. Comparing cubic form and parallelepiped (slice) one; results seem to show that thickness is the most important parameter governing the transfer phenomena during foodstuff convective drying. Three slices with thickness of 0.5 cm and surface area of 17, 82 and 112 cm2 respectively, dry better than cubic sample with a = 1 cm or a = 2 cm of arrest and having respectively 6 and 24 cm2 of surface area. All things seem to show that initial surface is not only the essential parameter; but also the thickness of the sample must be taken into account. Indeed, all of the samples with equal thickness (0.5 cm) and different exchange surfaces dry at the same time, about 210 min, comparing with cubic form 1 cm of arrest and 6 cm2 of surface and drying time of 230 min. A new parameter noted Dc called characteristic diameter is so considered to bridge the gaps. It is defined to be the diameter of the biggest sphere we can cut into a sample. This parameter is independent of form of the sample, and time increase with characteristic diameter increasing.

Drone-Based External Calibration of a Fully Synchronized Ku-Band Heterodyne FMCW Radar

This paper discusses a novel drone-based external radar calibration technique, which utilizes a metal sphere hanging from a drone. The advantages of drone-based calibration are introduced and applied to a dual intermediate-frequency frequency-modulation continuous-wave (FMCW) radar system, which was developed to detect a low radar cross section (RCS) target like a drone with high sensitivity. The developed radar system operates in 150-MHz bandwidth with a frequency sweeping time of $500~\mu \text{m}$ at Ku-band frequencies. A 75- $\Omega $ coaxial cable was utilized in the radar system to physically separate the transmitter (Tx) and receiver (Rx) modules for better isolation. The physical separation with a coaxial cable helps in reducing Tx leakage signal effect, which is a critical concern of typical FMCW radar system, and also it helps the proposed radar system to have higher sensitivity. The designed radar system is a wired system that is fully synchronized with an internal reference clock generator. Offset frequency and other compensation factors were calculated for the calibration of the radar system using a big size metal sphere hanging from a drone. We observed that the theoretical calculations using the standard radar equation and the measurement results on calibration are in good agreement with each other. Furthermore, the RCS value of a small size drone is also investigated using the calibrated radar system. The RCS value estimated for the drone was about −22 dBsm.

Optimisation of reconstruction, volumetry and dosimetry for 99mTc-SPECT and 90Y-PET images: Towards reliable dose-volume histograms for selective internal radiation therapy with 90Y-microspheres

PurposeIn Selective Internal Radiation Therapy (SIRT), 99mTc-MAA SPECT images are commonly used to predict microspheres distribution but recent works used 90Y-microspheres PET images. Nevertheless, evaluation of the predictive power of 99mTc-MAA has been hampered by the lack of reliable comparisons between 99mTc-SPECT and 90Y-PET images. Our aim was to determine the “in situ” optimisation procedure in order to reliably compare 99mTc-SPECT and 90Y-PET images and achieve optimal personal dosimetry. MethodsWe acquired 99mTc-SPECT/CT and 90Y-PET/CT images of NEMA and Jaszczak phantoms. We found the best reconstruction parameters for quantification and for volume estimations. We determined adaptive threshold curves on the volumetric reconstruction. We copied the optimised volumes on the quantitative reconstruction, named here the “cross volumes” technique. Finally, we compared 99mTc-SPECT and 90Y-PET Dose Volume Histograms. ResultsOur “in situ” optimisation procedure decreased errors on volumes and quantification (from −44.2% and −15.8% to −3.4% and −3.28%, respectively, for the 26.5mL PET phantom sphere). Moreover, 99mTc-SPECT and 90Y-PET DVHs were equivalent only after the optimisation procedure (difference in mean dose <5% for the three biggest spheres). ConclusionsThis work showed that a preliminary “in situ” phantom study was necessary to optimise volumes and quantification of 99mTc-SPECT and 90Y-PET images and allowed to achieve a reliable comparison between patient treatment planning and post implant dosimetry, notably by the use of the “cross volumes” technique. Methodology developed in this work will enable robust evaluations of the predictive power of 99mTc-SPECT, as well as dose-response relationship and side effects in SIRT treatments.

Abstract 5649: Cell-intrinsic PD-L1 directs tumor initiating cell fate and rapamycin and interferon-γ response

Abstract Tumor initiating cells (TIC) foster treatment resistance and tumor relapse. We show here that in mouse B16 (melanoma) and ID8agg (ovarian carcinoma), and human ovarian cancer ES2, PD-L1 knockdown (shRNA) reduced TIC numbers and functions. Data shown are from 2 PD-L1lo clones/cell type. Sorted, control CD44+CD133+CD24+ (B16), CD44+CD24+ (ID8agg) and ALDHhi (ES2) TIC formed 50-75% more and bigger spheres vs. PD-L1lo TIC in vitro, consistent with reduced TIC self-renewal in PD-L1lo. In vivo, PD-L1lo B16 and ID8agg TIC exhibited reduced tumorigenicity in wild type mice, consistent with poor TIC function, but immune effects could not be excluded. B16 and ES2 PD-L1lo TIC had significantly reduced tumorigenicity versus control TIC in immune deficient NSG mice consistent with cell-autonomous, immune-independent TIC promotion by PD-L1. In further confirmation, we found reduced serial transplantability of PD-L1lo B16 TIC in NSG mice. The canonical stemness genes nanog and pou5f1 (oct4) were significantly higher in control vs. PD-L1lo TIC for B16 and ID8agg. The canonical stemness gene SOX2 was significantly higher in control vs. PD-L1lo ES2 TIC. Altogether, these data validate effects in human cells, and are consistent with PD-L1 driving TIC through stemness gene control, although specific genes differed in distinct tumors (likely due to differing mutational landscapes). mTORC1 signaling linked to stemness (assessed by raptor) was lower but mTORC2 was unaffected (rictor) in PD-L1lo vs control TIC from all 3 tumors, suggesting mTORC1 control of PD-L1-mediated TIC generation. In support, the mTORC1 inhibitor rapamycin reduced control TIC significantly (&amp;gt;50% vs. untreated). Strikingly, rapamycin significantly increased PD-L1lo TIC in all 3 tumors, suggesting mTORC1 effects differ by tumor PD-L1 status. Interferon (IFN)-γ similarly reduced control TIC and augmented PD-L1lo TIC numbers, suggesting the novel concept that PD-L1 alters IFN-γ signals. PD-L1 sensitization of TIC to IFN-γ and rapamycin is the first example of a molecule enhancing TIC treatment response to our knowledge. We recently reported that αPD-L1 directly reduces B16 and ID8agg proliferation in vitro and in vivo (accession no. 27671674). Preliminary data now show that αPD-L1 (and αPD-1) directly reduce TIC proliferation, and these effects differ from non-TIC. We challenge the paradigm that tumor PD-L1 is primarily an immune escape molecule and that αPD-L1 works primarily to block T cell PD-1 interactions. Citation Format: Harshita B. Gupta, Curtis A. Clark, Bin Yuan, Gangadhara Sareddy, Srilakshmi Pandeswara, Alvaro S. Padron, Vincent Hurez, Jose-Conejo Garcia, Ratna Vadlamudi, Rong Li, Tyler J. Curiel. Cell-intrinsic PD-L1 directs tumor initiating cell fate and rapamycin and interferon-γ response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5649. doi:10.1158/1538-7445.AM2017-5649

14. Quantitative performance of a Signa PET/MR based on the NEMA NU 2-2007 standard

Introduction Our purpose was to assess the quantitative performance of a Signa PET/MR (GE Healthcare), which combines both TOF measurement and a 3T MRI. Methods The performance of a Signa PET/MR was evaluated based on the NEMA NU 2-2007 [1] . Analyses were performed with the manufacturer’s software. To characterize the image quality, the contrast activity between the 4 smallest spheres and the background was 4. The 2 biggest spheres were filled with non-radioactive water. A 10 mn acquisition was performed and the image was reconstructed with a 3D iterative TOF algorithm, without PSF. The recovery coefficient (RC) and the background variability (BV) of the spheres were calculated. The measurement of the spatial resolution was done using 3 point sources located in a transaxial plane, in the middle of the axial field-of-view (FOV), and shifted of 6.3 cm. The images were reconstructed with FBP. The Full Width at Half Maximum (FWHM) and the Full Width at Tenth Maximum (FWTM) of the sources in the axial and transverse directions were measured. The sensitivity was measured with different acquisitions of a 70 cm line source, containing 9 MBq and placed in differing amount of attenuation material. It was centered in the transverse FOV and then shifted of 10cm. The sensitivity was deducted dividing the extrapolated count rate without attenuation by the measured activity. Finally, the count rate and the scatter fraction (SF) were measured during 14 h thanks to a line source containing 830 MBq. The curves obtained (cf Fig. 1) allowed us to determine the activity concentration at maximum of NECR as well as the SF. Results The RC (%) and BV (%) for the 10, 13, 17, 22, 28 and 37 mm diameters spheres were 62.0/71.8/108.1/96.0/86.7/91.1 and 7.1/5.4/4.0/3.2/2.5/2.1, respectively. The mean FWHM/FWTM (in mm) of the punctual sources located at 1 and 10 cm from the central axis were 4.02/8.57 and 5.08/9.68 in transverse, and 5.70/11.40 and 7.41/14.70 in axial. The sensitivity in the centre of the FOV and at 10 cm were 23.5 and 22.8 cps/kBq. The activity concentration at maximum of NECR was 223 kcps for an activity concentration of 18.9 kBq/mL. This value was associated to a SF of 44.06%. Conclusions The performances of the Signa PET/MR were better than the manufacturer specifications. However, the image quality was not performed with an attenuation correction image obtained with the MRI but on a theoretical density phantom one. The characterization of this parameter does not allow for an evaluation of the quality of the attenuation correction provided by the MRI. Download : Download high-res image (218KB) Download : Download full-size image

Numerical investigation of dynamical behavior of tethered rigid spheres in supersonic flow

The dynamical behavior of two tethered rigid spheres in a supersonic flow is numerically investigated. The tethered lengths and radius ratios of the two spheres are different. The two spheres, which are centroid axially aligned initially, are held stationary first, then released, and subsequently let fly freely in a supersonic flow. The mean qualities of the system and the qualities of the bigger sphere are considered and compared with the situations without the tether. In the separation process, six types of motion caused by the spheres, tether, and fluid interaction are found. The results show that the mean x-velocity of the system changes in a different manner for different radius ratios, and the x-velocity of the bigger sphere is uniformly reduced but through different mechanisms.

Cross-modal influence on oral size perception

ObjectiveEvidence suggests people experience an oral size illusion and commonly perceive oral size inaccurately; however, the nature of the illusion remains unclear. The objectives of the present study were to confirm the presence of an oral size illusion, determine the magnitude (amount) and direction (underestimation or overestimation) of the illusion, and determine whether immediately prior cross-modal perceptual experiences affected the magnitude and direction. DesignParticipants (N=27) orally assessed 9 sizes of stainless steel spheres (1/16 in to 1/2 in) categorized as small, medium, or big, and matched them with digital and visual reference sets. Each participant completed 20 matching tasks in 3 assessments. For control assessments, 6 oral spheres were matched with reference sets of same-sized spheres. For primer-control assessments, similar to control, 6 matching tasks were preceded by cross-modal experiences of the same-sized sphere. For experimental assessments, 8 matching tasks were preceded by a cross-modal experience of a differently sized sphere. ResultsFor control assessments, small and medium spheres were consistently underestimated, and big spheres were consistently overestimated. For experimental assessments, magnitude and direction of the oral size illusion varied according to the size of the sphere used in the cross-modal experience. ConclusionResults seemed to confirm an oral size illusion, but direction of the illusion depended on the size of the object. Immediately prior cross-modal experiences influenced magnitude and direction of the illusion, suggesting that aspects of oral perceptual experience are dependent upon factors outside of oral perceptual anatomy and the properties of the oral stimulus.

An adaptive filtered back-projection for photoacoustic image reconstruction.

The purpose of this study is to develop an improved filtered-back-projection (FBP) algorithm for photoacoustic tomography (PAT), which allows image reconstruction with higher quality compared to images reconstructed through traditional algorithms. A rigorous expression of a weighting function has been derived directly from a photoacoustic wave equation and used as a ramp filter in Fourier domain. The authors' new algorithm utilizes this weighting function to precisely calculate each photoacoustic signal's contribution and then reconstructs the image based on the retarded potential generated from the photoacoustic sources. In addition, an adaptive criterion has been derived for selecting the cutoff frequency of a low pass filter. Two computational phantoms were created to test the algorithm. The first phantom contained five spheres with each sphere having different absorbances. The phantom was used to test the capability for correctly representing both the geometry and the relative absorbed energy in a planar measurement system. The authors also used another phantom containing absorbers of different sizes with overlapping geometry to evaluate the performance of the new method for complicated geometry. In addition, random noise background was added to the simulated data, which were obtained by using an arc-shaped array of 50 evenly distributed transducers that spanned 160° over a circle with a radius of 65 mm. A normalized factor between the neighbored transducers was applied for correcting measurement signals in PAT simulations. The authors assumed that the scanned object was mounted on a holder that rotated over the full 360° and the scans were set to a sampling rate of 20.48 MHz. The authors have obtained reconstructed images of the computerized phantoms by utilizing the new FBP algorithm. From the reconstructed image of the first phantom, one can see that this new approach allows not only obtaining a sharp image but also showing the correct signal strength of the absorbers. The reconstructed image of the second phantom further demonstrates the capability to form clear images of the spheres with sharp borders in the overlapping geometry. The smallest sphere is clearly visible and distinguishable, even though it is surrounded by two big spheres. In addition, image reconstructions were conducted with randomized noise added to the observed signals to mimic realistic experimental conditions. The authors have developed a new FBP algorithm that is capable for reconstructing high quality images with correct relative intensities and sharp borders for PAT. The results demonstrate that the weighting function serves as a precise ramp filter for processing the observed signals in the Fourier domain. In addition, this algorithm allows an adaptive determination of the cutoff frequency for the applied low pass filter.

The Semantic Field Theory as Applied to Phraseology

The article deals with the field method on the whole and as applied to phraseology in particular. Adaptation of semantic field into phraseology sphere is made necessary by the analysis needed within the frames of specified microsystems. Productivity and systematic description of field method may serve alternative to other methods of comparative research. The lexico-semantic system represents combination of semantic fields, with hierarchic structure. On the one hand it provides for the integration into the bigger spheres of lexicon, on the other hand the inclusion into inner structure of the micro-field with not so numerous units. The semantic fields are interconnected and the structure of their boundaries is comparative. Nowadays “a semantic field” term is widely used in the sphere of phraseology as well. Phrase-semantic field can be further subdivided into micro-fields and the last into groups. Such a division is aroused by heterogeneity of the language material examined. DOI: 10.5901/mjss.2015.v6n3s2p408

Atomistic Insights into the Interaction of Copper Oxide Surfaces with Chloride Ions in Aqueous Media

Corrosion of metals in aqueous environment, such as seawater, represents a technologically relevant electrochemical phenomenon involving complex chemical interactions at the metal-oxide/aqueous media interface. These interactions result in coupled electrochemical processes, such as, metal dissolution and reduction of agents in the environment. A fundamental understanding of these processes at the atomic level is an area of immense interest with applications not only in engineering, but also in catalysis and surface chemistry. To gain atomistic insights into such processes, we employ a model system consisting of copper oxide thin film on a copper substrate; the oxide film interacts with the chloride ions in the aqueous medium. Using extensive molecular dynamics simulations based on a reactive force field (ReaxFF), we systematically investigated the impact of (a) the stoichiometry of oxide film, and (b) solvation dynamics on the dissolution kinetics of Cu and adsorption of Cl on the Cu-oxide surface. Our MD simulations indicate that corrosion initiates via adsorption of Cl- ions on the Cu-oxide surface; these Cl- ions, in turn, bind with nearby Cu atoms causing dissociation of existing Cu-O bonds, and form soluble Cu-Cl complexes. These complexes dissolve in the aqueous media resulting in dissolution of Cu atoms and thinning of the oxide film. We found that upon increasing the oxygen content in the oxide film, the Cl- ion adsorption and Cu dissolution is severely impaired. For instance, increasing oxygen stoichiometry from 0.2 to 0.79 causes Cl-adsorption to drop by half. In other words, O-rich Cu-oxide films provide better corrosion resistance than O-deficient ones. Furthermore, our hydrogen-bond correlations show that water present in the aqueous media forms ordered layers on oxide films with high oxygen content; as the O-content is reduced, this order gets disrupted. Use of the Center for Nanoscale Materials was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Figure Caption: Temporal evolution of the interface between the passive oxide layer (at different oxygen stoichiometry) and aqueous medium at selected times during our MD simulations of corrosion. For the sake of clarity, the adsorbed chloride ions are shown as big spheres (green), while the copper (tan), oxygen (red), and hydrogen (blue) atoms are shown are shown are small spheres. Figure 1