Function Of Penetration Depth Research Articles

Effect of ‘in-plane’ contraction on the (0 0 1) surface of the model perovskite SrTiO3

Reflection high-energy electron diffraction in the temperature range 8–300 K revealed several surface structural transformations accompanied with a strong ‘in-plane’ lattice parameter growth on the (001) surface of the model perovskite SrTiO3 single crystal. Rather may occurring at sharp temperatures, these transformations are observed to extend over temperature intervals separated from each other by temperature zones where no structural changes occur and the crystal lattice is relaxed. In such relaxed zones the equilibrium lattice parameters were identified and analyzed as a function of penetration depth. A strong ‘in-plane’ contraction of the crystal lattice in the first surface layers was experimentally revealed at low temperatures and theoretically confirmed by hybrid DFT calculations. Along with such an ‘in-plane’ contraction of the (001) surface at low temperatures we have found that the thermal expansion on the surface is much higher than in the bulk which results in approaching of the surface ‘in-plane’ and the bulk lattice parameters at room temperature. This contradicts the general assumption that surface ‘in-plane’ and bulk lattice parameters are identical.

Effective mass accommodation for partitioning of organic compounds into surface films with different viscosities.

Indoor surfaces can act as reservoirs and reaction media influencing the concentrations and type of species that people are exposed to indoors. Mass accommodation and partitioning are impacted by the phase state and viscosity of indoor surface films. We developed the kinetic multi-layer model KM-FILM to simulate organic film formation and growth, but it is computationally expensive to couple such comprehensive models with indoor air box models. Recently, a novel effective mass accommodation coefficient (αeff) was introduced for efficient and effective treatments of gas-particle partitioning. In this study, we extended this approach to a film geometry with αeff as a function of penetration depth into the film, partitioning coefficient, bulk diffusivity, and condensed-phase reaction rate constant. Comparisons between KM-FILM and the αeff method show excellent agreement under most conditions, but with deviations before the establishment of quasi-equilibrium within the penetration depth. We found that the deposition velocity of species and overall film growth are impacted by bulk diffusivity in highly viscous films (Db ∼<10-15 cm2 s-1). Reactions that lead to non-volatile products can increase film thicknesses significantly, with the extent of film growth being dependent on the gas-phase concentration, rate coefficient, partitioning coefficient and diffusivity. Amorphous semisolid films with Db > ∼10-17-10-19 cm2 s-1 can be efficient SVOC reservoirs for compounds with higher partitioning coefficients as they can be released back to the gas phase over extended periods of time, while glassy solid films would not be able to act as reservoirs as gas-film partitioning is impeded.

Characterization of 304L laser welds using digital image correlation and x-ray computed tomography

304L stainless steel partial-penetration laser welds with varying penetration depths are needed for a variety of national security applications. Their mechanical performance depends on many parameters including weld schedule, penetration depth, and weld porosity. Unfortunately, these parameters are not easily divorced from one another as each has varying impacts upon the others. Therefore, an understanding of the interplay between these parameters as well as their impact on weld performance is rather useful. In this work, partial penetration laser welds are produced with four varying penetration depths at two different weld schedules. Mechanical testing is conducted to characterize the mechanical performance while full-field digital image correlation (DIC) is applied during testing to obtain the displacement field down to the micron-scale to better understand both global and local deformation behavior. Porosity of these welds is also investigated using x-ray computed tomography (XCT) prior to mechanical testing. The integration of DIC and XCT techniques with mechanical testing provides an expanded experimental dataset to evaluate the variations in mechanical response as a function of penetration depth, weld schedule and porosity. These experimental techniques also provide a promising approach for future study of laser performance.

ANALYSIS OF THE IMPACT OF BIOMATERIAL AND THE TECHNOLOGY OF PROSTHETIC CROWNS MANUFACTURING ON THE CONNECTION WITH VENEERING CERAMICS

The aim of the study is to identify the endurance parameters of prosthetic crowns veneered with dedicated ceramics on metal, glass-ceramic, and ceramic frameworks. Metal frameworks were made using CAD/CAM milling technology and SLM technology, while the glass-ceramic and ceramic frameworks were produced using only the CAD/CAM milling technology. The research materials are samples replicating the layered structures of prosthetic crowns. The veneering procedure must ensure the adhesion of the ceramics to the loadbearing framework. The tests modelling the conditions of concentrated loads during chewing were carried out using the Instron 3345 testing machine. Determination of microhardness in cross-sections through layered structures of crowns was performed using the HMV Micro Hardness Tester. The comparison of force loading the indenter as a function of penetration depth indicates that the value of the maximum depth depends on the configuration of microhardness of the framework and dentine. The zirconium ceramics ZrO2 (3Y-TZP) – veneered with Elephant Sakura silica ceramics – should be indicated as the most advantageous material composition.

Estimation of gamma-rays, and fast and the thermal neutrons attenuation characteristics for bismuth tellurite and bismuth boro-tellurite glass systems

Gamma-rays and fast and thermal neutron attenuation features of (Bi2O3)x–(TeO2)(100−x) (where x = 5, 8, 10, 12, and 15 mol%) and [(TeO2)0.7–(B2O3)0.3](1−x)–(Bi2O3)x (where x = 0.05, 0.10, 0,15, 0.20, 0.25, and 0.3 mol%) glass systems have been explored and compared. For all samples, mass attenuation coefficients (μ/ρ) are estimated within 0.015–15 MeV photon energy range by MCNP5 simulation code and correlated with WinXCom results, which showed a satisfactory agreement between computed μ/ρ values by these both methods. Additionally, effective atomic number (Zeff), effective electron density (Neff), half-value layer (HVL), tenth-value layer (TVL), mean free path (MFP), total atomic cross-section (σa), and total electronic cross-section (σe) are calculated by utilizing μ/ρ values. The μ/ρ, Zeff, and Neff are energy dependent and have higher values at the lowest energy and smaller values at higher energies. Moreover, using the G–P fitting method as a function of penetration depth (up to 40 mfp) and incident photon energy (0.015–15 MeV range), exposure buildup factors (EBFs) and energy absorption buildup factors (EABFs) are evaluated. Both 85TeO2–15Bi2O3 (mol%) and 49TeO2–21B2O3–30Bi2O3 (mol%) samples, by possessing higher values of Zeff, exhibit minimum EBF and EABF values. Highest μ/ρ, Zeff values and lowest HVL, TVL, MFP values of 49TeO2–21B2O3–30Bi2O3 (mol%) sample indicated its better gamma-ray absorption capability among all selected glasses. Further, macroscopic effective removal cross-section for fast neutrons (ΣR), coherent scattering cross-section (σcs), incoherent scattering cross-section (σics), absorption cross-section (σA), and total cross-section (σT) values for thermal neutron attenuation have been computed. Among all samples, 49TeO2–21B2O3–30Bi2O3 (mol%) glass possesses a better ΣR value for fast neutron attenuation, while the largest ‘σT’ value of 66.5TeO2–28.5B2O3–5Bi2O3 (mol%) sample suggests its good thermal neutron absorption efficiency.

Penetration force and cannula sliding profiles of different pen needles: the PICASSO study.

PurposePen needles used for insulin injections can have different characteristics that affect a patient’s injection experience. The aim of the study was to investigate in a standardized laboratory setting the penetration force and sliding force of different 31/32/33/34 gauge pen needles available in 3.5/4/5/8 mm length and 3/5 bevel tips for subcutaneous injection through pen needles and injection pens.MethodsEight different commercially available pen needles were tested in this experimental study. The needle was inserted into a polyurethane substrate at a specific constant speed and the force for insertion was recorded as a function of penetration depth. A load cell was utilized to measure force during the different stages of insertion.ResultsMaximum load was lower with the PiC G32×4 when compared with the G32×4 5-bevel needle (p<0.0001), while it was not significantly lower with the PiC G32×4 when compared to the G32×4 3-bevel needle (p=0.064). The comparison of G33×4 PiC and G34×3.5 PiC needles with G32 needles demonstrated significantly lower maximum loads with G33 and G34 (p<0.0001). No difference between needles emerged for sliding results.ConclusionNewer pen needles represent a significant improvement in insulin delivery, reducing the amount of force required to penetrate tissues. Needle tip sharpness and other factors that can reduce the force of insertion such as lubrication are important parameters that can be optimized to increase patient acceptance.

Correlation of microstructure and constitutive behaviour of sintered silver particles via nanoindentation

During the sintering process, a three-dimensional network-like porous structure forms as the consequences of atom diffusion and neck formation among silver particles. In this paper, two representative types of pressureless sintered silver particles, i.e., silver nanoparticles (AgNP) and silver microparticles (AgMP), are investigated to reveal the intrinsic correlation between microstructure and constitutive behaviour. The heterogeneous microstructure is found to result in distinguishing differences in terms of morphology and thermal stability. The difference of sintering mechanisms between these two types of silver pastes are observed by a scanning electron microscope and discussed. Regarding thermal stability, the effect of particle size and shape on the sintering temperature and mass loss are evaluated using the thermogravimetric analysis and the differential scanning calorimetry. The microstructural effect on the mechanical behaviour of both sintered AgNP and AgMP samples is measured by performing nanoindentations with a Berkovich indenter penetrated up to 2000 nm with different indentation strain rates. During indentation, Young's modulus and hardness are measured as the functions of penetration depth. By solving dimensionless equations, the parameters of a power-law constitutive model are obtained analytically based on the integrated work done in the loading stage and the contact stiffness in the unloading stage in the nanoindentation experiments. The correlation between microstructure and constitutive behaviour is elucidated by the comparison of sintered AgNP and AgMP but further investigations related to the size and shape effects of particles are expected.

Energy-absorption buildup factors of some fluorides and sulfates: thermoluminescent dosimetric materials

Gamma ray energy-absorption buildup factors were computed, using the five-parameter Geometric Progression fitting formula and the ANSI/ANS-6.4.3 report, for some fluorides and sulfates in the energy range 0.015−15 MeV, and for penetration depths up to 40 mfp. The generated energy-absorption buildup factors are studied as functions of penetration depth and incident photon energy. At a given penetration depth, the buildup factor first increases, reaching a maximum value, and then decreases with increasing energy. The maximum value of the buildup factor occurs in the energy range 0.15–0.3 MeV. At these energies, Compton scattering is the major photon interaction process, and photoelectric absorption is of relatively little importance, leading to large buildup factors. The results of the present work should be useful in radiation dosimetry, diagnostics and therapy. The tissue equivalence of these materials is also discussed. It is found that lithium fluoride can be effectively used as a tissue equivalent material for cortical bone in the energy region 0.2−2 MeV.

Calibration of a Constitutive Model from Tension and Nanoindentation for Lead-Free Solder.

It is challenging to evaluate constitutive behaviour by using conventional uniaxial tests for materials with limited sizes, considering the miniaturization trend of integrated circuits in electronic devices. An instrumented nanoindentation approach is appealing to obtain local properties as the function of penetration depth. In this paper, both conventional tensile and nanoindentation experiments are performed on samples of a lead-free Sn–3.0Ag–0.5Cu (SAC305) solder alloy. In order to align the material behaviour, thermal treatments were performed at different temperatures and durations for all specimens, for both tensile experiments and nanoindentation experiments. Based on the self-similarity of the used Berkovich indenter, a power-law model is adopted to describe the stress–strain relationship by means of analytical dimensionless analysis on the applied load-penetration depth responses from nanoindentation experiments. In light of the significant difference of applied strain rates in the tensile and nanoindentation experiments, two “rate factors” are proposed by multiplying the representative stress and stress exponent in the adopted analytical model, and the corresponding values are determined for the best predictions of nanoindentation responses in the form of an applied load–indentation depth relationship. Eventually, good agreement is achieved when comparing the stress–strain responses measured from tensile experiments and estimated from the applied load–indentation depth responses of nanoindentation experiments. The rate factors and are calibrated to be about 0.52 and 0.10, respectively, which facilitate the conversion of constitutive behaviour from nanoindentation experiments for material sample with a limited size.

Influence of Tcnq Loading on the Mechanical Properties of Metal-Organic Framework Films

Bulk Metal-organic-framework (MOF) materials are designed scaffold-like compounds that consist of metal ions connected by organic ligands, forming highly ordered porous structures. Bulk MOFs yield typically powders with micron sized crystallites, which limit their applications. Many practical applications require instead suitably uniform MOF films. In recent years, efforts to grow highly oriented Surface Anchored Metal-Organic Framework (SURMOF) films of Cu3(BTC)2 (BTC: benzenetricarboxylic acid), known as HKUST-1 MOF, have been successful by utilizing a liquid phase epitaxy (LPE) spray method on surface functionalized gold coated silicon substrates. Originally MOFs were intended for gas storage due to high storage capacity inside the porous MOF bulk material. New potential device applications in thermoelectrics and microelectronics [1,2] were explored based on the premise that the electrical properties of the otherwise insulating MOF can be custom tailored by loading the porous MOF structure with metal clusters. For modulating the electrical conductivity of MOF films the most effective method is to infiltrate guest molecules inside the porous framework to transport ions, and hence to modulate the electrical properties of the host framework. Early work focused on the mechanical properties of pristine SURMOF films [3,4]. In this study, we have investigated the influence of loading pristine highly oriented MOF films with TCNQ on the mechanical properties by utilizing nanoindentation methods to measure the hardness and modulus of SURMOF films with and without TCNQ loading. Our findings reveal that undoped pristine SURMOF samples are relatively harder with an intrinsic hardness of ~ 1.6 GPa in the upper third of the MOF film. The hardness of the pristine SURMOF samples is steadily increasing as a function of the penetration depth. The hardness is approaching the substrate Si hardness as the indenter tip approaches the substrate. The measured modulus values of the pristine SURMOF samples are also steadily increasing as a function of the indentation depth. However, the TCNQ loaded SURMOF samples differ markedly and do not show a substrate effect. Interestingly the loaded SURMOF films are much softer and exhibit a constant hardness as a function of depth of ~ 0.5 GPa. As the indenter approaches the Si substrate there is no measurable change in the constant hardness and an absence of a substrate effect. The modulus values of TCNQ loaded SURMOF films is also significantly lower compared with the pristine sample and remains constant as a function of indenter penetration depth. Thus, loading the porous scaffolding of SURMOF films with TCNQ did not only alter the electrical conductivity but triggers marked changes in the mechanical properties, i.e., softening effect. This softening effect in TCNQ infiltrated MOF films can be accounted for by a widening of the lattice constant und the concomitant introduction of lattice defects that weaken the crystal and lead to a much lower hardness.

Optimal control RF pulses for excitation and suppression of NMR signals in a conductive medium.

In this work, optimal control theory was used to design efficient excitation schemes in highly conductive materials, where both the radio frequency field strength and phase vary as a function of penetration depth. A pulse was designed to achieve phase alignment between signals at different depths within the conductor and thus to obtain higher signals from that region. In addition, an efficient suppression pulse was designed by insuring mutual suppression between the signals from various depths in the sample. The performance of the new approach was demonstrated experimentally for a bulk lithium sample for the excitation problem and for a biphasic metal/liquid sample for the selective suppression pulse.

Influence of TCNQ Loading on the Mechanical Properties of Metal-Organic Framework Films

Bulk Metal-organic-framework (MOF) materials are designed scaffold-like compounds that consist of metal ions connected by organic ligands, forming highly ordered porous structures. Bulk MOFs yield typically powders with micron sized crystallites, which limit their applications. Many practical applications require instead suitably uniform MOF films. In recent years, efforts to grow highly oriented Surface Anchored Metal-Organic Framework (SURMOF) films of Cu3(BTC)2 (BTC: benzenetricarboxylic acid), known as HKUST-1 MOF, have been successful by utilizing a liquid phase epitaxy (LPE) spray method on surface functionalized gold coated silicon substrates. Originally MOFs were intended for gas storage due to high storage capacity inside the porous MOF bulk material. New potential device applications in thermoelectrics and microelectronics [1,2] were explored based on the premise that the electrical properties of the otherwise insulating MOF can be custom tailored by loading the porous MOF structure with metal clusters. For modulating the electrical conductivity of MOF films the most effective method is to infiltrate guest molecules inside the porous framework to transport ions, and hence to modulate the electrical properties of the host framework. Early work focused on the mechanical properties of pristine SURMOF films [3,4]. In this study, we have investigated the influence of loading pristine highly oriented MOF films with TCNQ on the mechanical properties by utilizing nanoindentation methods to measure the hardness and modulus of SURMOF films with and without TCNQ loading. Our findings reveal that undoped pristine SURMOF samples are relatively harder with an intrinsic hardness of ~ 1.6 GPa in the upper third of the MOF film. The hardness of the pristine SURMOF samples is steadily increasing as a function of the penetration depth. The hardness is approaching the substrate Si hardness as the indenter tip approaches the substrate. The measured modulus values of the pristine SURMOF samples are also steadily increasing as a function of the indentation depth. However, the TCNQ loaded SURMOF samples differ markedly and do not show a substrate effect. Interestingly the loaded SURMOF films are much softer and exhibit a constant hardness as a function of depth of ~ 0.5 GPa. As the indenter approaches the Si substrate there is no measurable change in the constant hardness and an absence of a substrate effect. The modulus values of TCNQ loaded SURMOF films is also significantly lower compared with the pristine sample and remains constant as a function of indenter penetration depth. Thus, loading the porous scaffolding of SURMOF films with TCNQ did not only alter the electrical conductivity but triggers marked changes in the mechanical properties, i.e., softening effect. This softening effect in TCNQ infiltrated MOF films can be accounted for by a widening of the lattice constant und the concomitant introduction of lattice defects that weaken the crystal and lead to a much lower hardness.

Efficacy of Fluoride Varnishes with Added Calcium Phosphate in the Protection of the Structural and Mechanical Properties of Enamel.

The aim of this study was to investigate the efficacy of various fluoride varnishes in the protection of the structural and nanomechanical properties of dental enamel. Demineralized enamel specimens were imaged using a high-resolution micro-CT system and lesion parameters including mineral density and lesion depth were extracted from mineral density profiles. Nanoindentation elastic modulus and hardness were calculated as a function of penetration depth from the load-displacement curves. The average depth of the lesion in specimens with no prior fluoride varnish treatment was 86 ± 7.19 μm whereas the varnish treated specimens had an average depth of 67 ± 7.03 μm (P < 0.05). The mineral density of enamel lesions with no fluoride varnish treatment had an average of 1.85 gr/cm3 which was 25% lower than the corresponding value in varnish treated enamel and 37% lower than sound enamel. While, in the varnish treated group, elastic modulus and hardness values had decreased by 18% and 23%, respectively, the corresponding values in the non-varnish treated specimens had a reduction of 43% and 54% compared to the sound enamel. The findings from this study highlight the preventive role of fluoride varnishes. Addition of calcium and phosphate does not seem to enhance or inhibit the prevention or remineralization performance of fluoride varnishes.

Study on Proton Radiation Resistance of 410 Martensitic Stainless Steels under 3 MeV Proton Irradiation

In this study, we report on an investigation of proton radiation resistance of 410 martensitic stainless steels under 3 MeV proton with the doses ranging from <TEX>$1.0{\times}10^{15}$</TEX> to <TEX>$1.0{\times}10^{17}p/cm^2$</TEX> at the temperature 623 K. Vibrating sample magnetometer (VSM) and X-ray diffractometer (XRD) were used to study the variation of magnetic properties and structural damages by virtue of proton irradiation, respectively. VSM and XRD analysis revealed that the 410 martensitic stainless steels showed proton radiation resistance up to <TEX>$10^{17}p/cm^2$</TEX>. Proton energy degradation and flux attenuations in 410 stainless steels as a function of penetration depth were calculated by using Stopping and Range of Ions in Matter (SRIM) code. It suggested that the 410 stainless steels have the radiation resistance up to <TEX>$5.2{\times}10^{-3}$</TEX> dpa which corresponds to neutron irradiation of <TEX>$3.5{\times}10^{18}n/cm^2$</TEX>. These results could be used to predict the maintenance period of SUS410 stainless steels in fission power plants.

Nanoscratching meets nanoindentation

Abstract A specimen of high-carbon nitrogen-doped steel has been synthesized to supplement previous studies on wootz-like steels. A comparison of different states of material as well as one of distinct methods of hardness testing has been performed. Electron microscopy of the specimens’ microstructure revealed nano-structuring similar to that observed with ancient sabers. Part of them was annealed so that the nano-structures dissolved. Nano-hardness values derived under ambient conditions from indentation as well as from scratch tests were determined and related to the microstructure prior to and after annealing. The disappearance of nanostructuring led to a significant drop of hardness. The ratio of indentation to scratch hardness proved a suitable indicator of hardening. From hardness as function of penetration depth and from friction as function of time and normal load various quantitative features of the mechanical properties and of the deformation process have been evaluated. When modeling friction, sliding and plowing parts have been distinguished quantitatively. Enhanced adhesion forces were attributed to surface layers.

Semi-empirical relationship for the energy absorption buildup factor in some biological samples

Energy absorption buildup factors in the energy range of 0.2 MeV to 2 MeV using a geometric progression fitting approximation in some selected essential amino acids, fatty acids and carbohydrate molecules have been obtained. A semi empirical relation-ship describing energy absorption buildup factors as a function of penetration depth, Compton scattering and energy absorption cross-section is used. This semi empirical method was defined in an earlier work on water and soft tissue by one of the present authors. We used this method for the calculating energy absorption buildup factor in biological samples. The results are compared with the energy absorption buildup factors data of the geometric progression fitting method. Good agreement between semi empirical and geometric progression fitting methods has been observed, so that average deviation is less than 2 % for all samples.

An LCP method for dynamics of planar-motion rigid-body with non-symmetric friction

A modeling and numerical calculation method for the dynamics of the rigid-body in planar motion with contact,impact,symmetric and non-symmetric Coulomb's dry friction was presented based on the theory of contact mechanics and the arithmetic of linear complementarity problem( LCP). The local deformations in contact bodies were taken into account although bodies were assumed to be rigid. The normal contact forces were expressed as nonlinear functions of penetration depth and its speed. The friction law adopted symmetric or non-symmetric Coulomb's dry friction model. Firstly,by using the friction saturation,the positive and negative parts of the relative acceleration of contact points,the complementarity conditions and formulations about the friction law were given in order to determine state transitions of stick-slip in numerical method.Then,based on the event-driven scheme,the problems of detecting stick-slip state transitions and solving frictional forces in stick situation were formulated and solved as a linear complementarity problem. Finally,the numerical example of a planar-motion rigid-body was given to analyze its dynamical behaviour affected by symmetric or non-symmetric Coulomb's dry friction and shown that the proposed method was effective.

A novel micromechanical model of nonlinear compression hysteresis in compliant interfaces of multibody systems

A micromechanical model of nonlinear hysteretic compression between interacting bodies of multibody systems, covered with fibrous structures, has been created and validated experimentally in this work. As an application, a multibody dynamic model of an upright piano action mechanism with felt-covered contacting bodies is considered, and the obtained results were verified using experiments. Felt, as a typical nonwoven fiber assembly, has been used in various contact surfaces of piano action mechanisms to transfer the force applied on the key to other components, smoothly and continuously. To keep the simulation time tractable in the mechanistic multibody dynamic model, interaction between felt-lined interfaces has to be simplified enough so that in each step of simulation time, contact forces can be calculated as a function of penetration depth between colliding objects. The developed micromechanical approach is capable of estimating nonlinear bulk response of felt in terms of microstructural parameters of the network, assuming a binomial distribution of the number of fiber contacts and bending of constituent fibers. Hysteresis is included based on a fiber-to-fiber friction approach, which generates a speed-independent response to compressive loading schemes, as has been observed in experiments. A computational algorithm is introduced to apply the sophisticated hysteretic micromechanical model to the multibody systems simulation, including transitions between loading–unloading stages.

Selective Probing of the Penetration of Dexamethasone into Human Skin by Soft X-ray Spectromicroscopy.

Selective probing of dexamethasone in excised human skin using soft X-ray spectromicroscopy provides quantitative concentration profiles as well as two-dimensional drug distribution maps. Element- and site-selective excitation of dexamethasone at the oxygen K-edge with the lateral step width adjusted to 1 μm provides detailed information on the location of the drug in the different skin layers. The key of this work is to probe dexamethasone selectively at the carbonyl site (C3) by the O 1s → π* transition, providing also a most efficient way to quantify the drug concentration as a function of penetration depth in correlation with structural properties of the skin containing carboxyl and amide oxygen sites occurring at higher transition energy than dexamethasone. Following drug exposure for 4 h, the glucocorticoide is located in about equal amounts in the stratum corneum, the outermost horny layer of skin, and in the viable epidermis, whereas in the dermis no dexamethasone is detected. In the stratum corneum, most of the lipophilic drug is found in regions between corneocytes, where epidermal lipids are dominating.

Solvent determines nature of effective interactions between nanoparticles in polymer brushes.

We study the effective interaction between two parallel rod-like nanoparticles in swollen and collapsed polymer brushes as a function of penetration depth by 2D self-consistent field calculations. In vertical direction, the interaction is always attractive. In lateral direction, the behavior under good and poor solvent conditions is qualitatively different. In swollen brushes (good solvent), nanoparticles always repel each other. In collapsed brushes (poor solvent), we identify two different regimes: an immersed regime, where the nanoparticles are fully surrounded by the brush, and an interfacial regime, where they are located in the interface between brush and solvent. In the immersed regime, the lateral interactions are repulsive, in agreement with previous theoretical predictions. In the interfacial regime, they are governed by the deformations of the interface and tend to be attractive. This implies that the nature of nanoparticle interactions can be manipulated by changing the solvent condition. The influence of particle size and grafting density are also briefly discussed.