Film Saturation Research Articles

Chemical‐Strain‐Engineered Adaptive Interfaces in Nanocomposite Films for Robust Ferroelectricity

AbstractStrain is an effective means of tuning the crystal structure to obtain a variety of fascinating properties, but how to apply flexible strain to meet the different needs of the film at each location has rarely been reported. In this study, a novel approach for designing strain‐damping structures that facilitate the imposition of flexible strain is introduced. A wide range of strain modulation is demonstrated in SmCoO3 films (a‐axis:+4.5%–+1.7%, b‐axis: +3.2%–+0.4%, c‐axis:+2.2%–+1.4%) under positive pressure by introducing Sm2O3 as a dopant. When SmCoO3 films are subjected to triaxial tensile strain, they exhibit a ferroelectric polarization of 7.12 µC cm−2. Through positive pressure modulation, resulting in a further increase in the ferroelectric polarization (up to 11.62 µC cm−2, which represents the maximum performance of the orthogonal rare earth transition metal oxide family). Moreover, the electron spin order can be effectively controlled, and the film's saturation magnetization increases to 14.83 emu cm−3 (+94.1%). This damping structure allows for flexible modulation of chemical strain in epitaxial film, achieving a delicate balance between film strain and structure, which provides valuable insights for all ferroelectrics based on structural distortion.

Effect of initial water saturation and water film on imbibition behavior in tight reservoirs using nuclear magnetic resonance technique

Initial water saturation has a significant influence on spontaneous imbibition, and it impacts the imbibition rate and imbibed liquid dynamic distribution among pore networks. At present, the effect of initial water saturation on spontaneous imbibition is still unclear, especially the water film effect caused by initial water saturation varies during imbibition. To address these issues, we prepared the samples with varied initial water saturation through vapor adsorption and then conducted spontaneous imbibitions on these samples, which were monitored by nuclear magnetic resonance (NMR). Samples were selected from tight sandstone reservoirs in the eastern Ordos Basin. From the NMR spectrum corresponding to different imbibition duration, the left wing of the left peak at the initial water saturation is usually higher than the ones after imbibition, mainly caused by the water film effect. When the water film on the surface of large pores is too thin, it is prone to be interpreted as water in small pores because the water film has a quick relaxation time than the water in the center part of pores. The water film effect disappears when the whole pores are filled with water, and the inversed small pores decrease. The relaxation time of the water film is shorter than 0.51 ms in the tested samples. This study is conducive to understanding the effect of initial water saturation on liquid dynamic distribution during imbibition, especially the water film effect variation during imbibition and the T2 value of the water film.

Domain wall velocity asymmetries driven by saturation magnetization gradients without a Dzyaloshinskii-Moriya interaction

The discovery of asymmetric domain wall velocities in magnetic alloys and multilayers without a heavy metal underlayer has given rise to claims of a large Dzyaloshinskii-Moriya interaction (DMI) driven by compositional non-uniformities. However, these non-uniformities also give rise to vertically non-uniform magnetic properties which can influence the dynamic properties of domain walls. In this work, we use micromagnetic simulations to show that vertical modulation of the saturation magnetization can give rise to asymmetric domain wall velocities for field and current driven motion, closely resembling the presence of a DMI. For field driven motion, by comparing the velocity asymmetries for varying saturation magnetization gradients, film thicknesses, and average saturation magnetization, we show that the magnitude of effective symmetry breaking field resulting from the non-uniformity can be comparable to those resulting from DMI. These effects scale with thickness and degree of modulation, mirroring recent results in single layer materials. However, the scaling of domain velocity asymmetries is largely suppressed for SOT driven domain dynamics. Therefore, great care needs to be taken when evaluating DMI in non-uniform systems.

Characterization of the ZAP-X® Peripheral Dose Fall-Off.

Various small-field radiation dose detectors were systematically compared and their impact on measured beam performance of the ZAP-X® dedicated stereotactic radiosurgery system (ZAP Surgical Systems, Inc., San Carlos, CA, USA) was determined. Three Physikalische Technische Werkstaetten (PTW) diodes, i.e., the microSilicon, the microDiamond, and the Stereotactic Radiosurgery (SRS) diode detectors of (PTW-Freiburg, Freiburg, Germany), as well as Gafchromic™ External Beam Therapy 3 (EBT) film (Ashland, Inc., Wilmington, DE, USA), were used and compared to arrive at a recommended standard for this critical component of small-field beam measurements. Beam profiles, including the dose fall-off region near the edge of the beam, were measured with the PTW diodes and EBT3 film and subsequently contrasted. The impact of detector physical and dosimetric characteristics on the results of the measurements was investigated and compared with film measurements. The beam penumbra was used to quantify the dose fall-off. The measurement acquired with the diodes and film showed the most significant differences in the fall-off region near the field edge. The film-based measurements clearly showed the steepest dose gradient verified by the penumbra value of 1.21 mm, followed by the SRS diode with 1.60 mm, the microSilicon diode with 1.67 mm, and the microDiamond diode with 1.83 mm. A clear correlation of each detector’s sensitive area with the penumbra was found, with the microDiamond detector at 2.2 mm diameter sensitive area having the largest penumbra, followed by the microSilicon and SRS diodes. Beam measurements for the purposes of system characterization or treatment planning system beam data acquisition depend, to a large extent, on detector characteristics. This is especially true for small-field dosimetry performed during stereotactic radiosurgery beam measurements. Careful consideration should be practiced which allows for the measurements to represent true beam characteristics and minimize the impact of the detector on the measurements. We conclude that film should be considered the reference method for such measurements with the ZAP-X due to its smallest physical measurement resolution of 23.1 µm. Potential drawbacks to this methodology are the need to calibrate the film relative to the dose and possible problems with saturation and non-linear film response for very high and very low optical densities.

Determination of the enthalpy of adsorption of hydrogen in activated carbon at room temperature

The development of high-performance materials for hydrogen storage by adsorption requires detailed understanding of the adsorbate-adsorbent interactions, e.g., the enthalpy of adsorption ΔH, which measures the interaction strength. The determination of ΔH for a weakly adsorbing gas such as hydrogen in a carbonaceous porous material is difficult experimentally, normally requiring measuring two cryogenic adsorption isotherms. Here we demonstrate a calculation of ΔH based on ca. room temperature adsorption isotherms at 273 K and 296 K using the Clausius-Clapeyron equation. This requires an estimation of the volume of the adsorbed film (~40%, ~12% of the total pore volume at 77 K, 296 K, respectively) obtained from fits of the excess adsorption isotherms to an Ono-Kondo model with the auxiliary use of a fixed point corresponding to the saturation film density (estimated as 100 ± 20 g/L) which appears to be remarkably sample and temperature independent, i.e., a property of the adsorbate. The calculated room temperature enthalpy of adsorption ΔH = 8.3 ± 0.4 kJ/mol is in excellent agreement with the low-coverage cryogenic determination of ΔH. The methodology hereby proposed facilitates reliable calculations of the enthalpy of adsorption at room temperatures for weakly-adsorbing gases.

Electrical and magnetic properties of (Al, Co) co-doped ZnO films deposited by RF magnetron sputtering

In this work, (Al, Co)-ZnO films were co-sputtered on glass substrate through radio frequency sputtering at 100 °C. The film's structure, electrical and magnetic properties as a function of Al doping content is investigated. The results indicate that (Al, Co)-ZnO films crystallinity can be suppressed by Co doping or (Co, Al) co-doping. With the substitution of Zn2+ by Al3+, the film's conductivity improves. All the films present ferromagnetic behavior at room temperature. Upon increasing the Al doping amount, the film's saturation magnetization expresses a carrier-concentration dependent behavior. Three different regions can be defined, where BMP model and carrier-mediated exchange mechanisms play a role in the various regions.

Simulation of boil-off losses during transfer at a LH2 based hydrogen refueling station

Losses along the LH2 pathway are intrinsic to the utilization of a cryogenic fluid. They occur when the fluid is transferred between 2 vessels (liquefaction plant to trailer, trailer to station storage, station storage to pump or compressor, then possibly onto fuel cell electric vehicles …) and when it is warmed up due to heat transfer with the environment. Those losses can be estimated with good accuracy using thermodynamic models based on the conservation of mass and energy, provided that the thermodynamic states are correctly described. Indeed, the fluid undergoes various changes as it moves along the entire pathway (2 phase transition, sub-cooled liquid phase, super-heated warming, non-uniform temperature distributions across the saturation film) and accurate equations of state and 2 phase behavior implementations are essential. The balances of mass and energy during the various dynamics processes then enable to quantify the boil-off losses. In this work, a MATLAB code previously developed by NASA to simulate rocket loading is used as the basis for a LH2 transfer model. This code implements complex physical phenomena such as the competition between condensation and evaporation and the convection vs. conduction heat transfer as a function of the relative temperatures on both sides of the saturated film. The original code was modified to consider real gas equations of state, and some semi-empirical relationships, such as between the heat of vaporization and the critical temperature, were replaced by a REFPROP equivalent expression, assumed to be more accurate. Non-constant liquid temperature equations were added to simulate sub-cooled conditions. The model shows that under environmental heat transfer only the liquid phase of a LH2 vessel would experience cooling, while the boil-off is mainly a result of evaporation from the saturation film onto the vapor phase. Under the conditions assumed for this work, it was also concluded that the actual LH2 density was lower than the corresponding saturation density given by the working pressure of the vessel. During a bottom fill transfer, for example from a LH2 trailer to an on-site stationary vessel, it is shown that the boil-off losses are due to the compression of the vapor phase (“pdV” force). The model indicates that the magnitude of those losses is not dependent on the regulated pressure in the receiving vessel but is rather a function of the initial pressure in the vessel, amounting to more than 12% of losses for a vessel initially at 100 psia. At last, the model is used to estimate the amount of vapor H2 vented when depressurizing a LH2 trailer following a LH2 delivery.

Vitrification conditions and porosity prediction of CO2 blown polystyrene foams

Experiments with CO2-blown hanging polystyrene (PS) films were carried out. The porosity of foams decreased with decreasing film thickness, indicating thus effects of heat and/or mass transfer. Taking into account the Joule–Thomson effect, mathematical model based on a simplified heat balance for the system PS+CO2 at the conditions of PS saturation with CO2 on one side and at the conditions of foam vitrification at glass transition temperature on the other side was derived to estimate the foam porosity. The model was applied to data on CO2-blown hanging films as well as literature data on foaming of PS particles. The trends of porosity dependence on saturation temperature and film thickness predicted by the model correspond to experimental results. The Joule–Thomson effect included in the modelling of the CO2 foaming process significantly affects the foam porosity and improves the predictive capabilities of simple model based on enthalpy balance and thermodynamic data.

The effect of a drainage layer on the saturation of coalescing filters in the filtration process

The effect of a drainage layer on the saturation of coalescing filters was evaluated experimentally. The effect of the pore size of a drainage layer on the saturation was demonstrated using the capillary theory. The experimental results showed that the filter without a drainage layer began to drain in the liquid film forming stage, where the flow resistance of the liquid in the channels increased significantly, resulting in the increases in both the saturation of the filter and the thickness of the liquid film. The pressure drop, saturation and liquid film thickness profiles varied after assembling a drainage layer outside of the coalescing layer. There was an adjustment stage of the liquid film in the filtration process of the filter with a non-wettable drainage layer, which can be verified by the evolution of the thickness of the liquid film predicted using theoretical calculations. The amount of the liquid increased gradually between the coalescing layer and the drainage layer at this stage, resulting in a significant increase in the saturation of the coalescing layer. As assembling a wettable drainage layer, a pseudo-steady state appeared, where the pressure drop and penetration were steady while the saturation of each layer increased. After the pressure drop increased and became steady again, the drainage led to a drastic increase in the saturation of the coalescing layer. At steady state of all the filters, the drainage rate and loading rate were almost the same. Furthermore, the capillary theory can be used to analyze the variation on the saturation affected by the pore sizes of a wettable drainage layer. Smaller pore size led to stronger capillarity, resulting in more liquid absorbed into the drainage layer and greater saturation of the coalescing layer.

Time evolution of domain-wall motion induced by nanosecond laser pulses

The time evolution of the magnetization normal component change in a garnet film with a labyrinthine domain structure under the action of circularly and linearly polarized laser pump pulses (the pulse duration is 5 ns; the wavelength is 527 nm) has been studied. The dynamic state of the magnetic film was registered using an induction method with a time resolution of 1 ns. It was found that for the initial state of the magnetic film with an equilibrium domain structure, the form of the photomagnetization pulse reflects the time evolution of a domain-wall motion. The domain-wall motion initiated by the circularly polarized laser pump pulse continues in the same direction for a time more than an order of magnitude exceeding the laser pulse duration. In general, the time evolution of the domain-wall movement occurs in three stages. The separation of the contributions to the photomagnetization from the polarization-dependent and polarization-independent effects was carried out. The photomagnetization pulses that reflect the contributions by the aforementioned effects differ by form, and more than two orders of magnitude by duration. Their form doesn't change under a magnetic bias field change, only the photomagnetization pulse amplitude does: for the polarization-dependent contribution, it's an even function of the field, and for the polarization-independent contribution, it's an odd function. The interconnection between the polarization-dependent and polarization-independent effects, on the one hand, and the domain-wall displacement and the change of the film's saturation magnetization, on the other hand, was identified and described.

Top-down control of dynamic anisotropy in permalloy thin films with stripe domains

Permalloy films with different thickness were prepared for comparison, and the dynamic properties of the stripe domains were investigated by using a vector network analyzer ferromagnetic resonance (VNA-FMR) technique. A top-down approach was used to control the thickness of the films. In the measurement of permeability spectra, an applied magnetic field Happ was employed parallel and perpendicular to the stripe domains, respectively. Dynamic pseudo-uniaxial anisotropy fields are derived. In order to explain the anisotropy variation of permalloy films, a theoretical model has been proposed, and the result shows that the pseudo-uniaxial anisotropy can be attributed to the contributions of saturation magnetization, exchange interaction, perpendicular anisotropy, and film thickness. In addition, with the increase of Happ, the stripe domains gradually rotate towards the direction of the applied field, which can be clearly observed by magnetic force microscopy. Moreover, the dynamic permeability spectra exhibit a rhythmic variation dependent on the rotation of the stripe domains, i.e. the relationship between the rotational stripe domains and resonance frequency.

Significance of Red Cell Distribution Width in the Diagnosis of Iron Deficiency Anemia: An Observational Study from India

Objective: To study the importance of Red cell distribution width (RDW) and peripheral smear in Iron Deficiency anemia (IDA) and its correlation with various RBC indices. Method and material: Hundred cases of microcytic (MCV <80fl) anemia (Hb<11 gm %), diagnosed as IDA were enrolled in the study, after getting parental consent. These children's were evaluated for clinical examination, red cell indices, RDW, serum iron and serum total iron binding capacity (TIBC) and transferrin saturation and peripheral blood film (PBF) examination for red cell morphology. Results: The mean RDW in mild, moderate and severe grade of iron deficiency anemia were 16.83±1.24, 18.52%+1.54 and 21.4%+3.15 respectively. The RDW was high in 98% cases of IDA.As the severity of IDA increased the values of RDW increased, serum iron decreased (p<0.001), TIBC increased (p<0.001) and serum transferrin saturation decreased (p<0.001). There was progressive decrease in MCV with increase in severity of anemia and there was corresponding increase in RDW. In mild IDA, the sensitivity of RDW was found to be very high (91%) in comparison to PBF changes (43.47%) cases and was statistically highly significant (p<0.001). In moderate IDA and severe IDA the sensitivity of RDW & PBF changes both were found to be very high. The positive predictive value of RDW and peripheral blood film changes was (100%) in all grades of IDA. The negative predictive value of RDW in mild grade of IDA was 88.23% as compared to 53.57% in PBF. In moderate grade of IDA, NPV of RDW was 100% as compared to 83% in case of PBF. While in severe grade of IDA the NPV of RDW and PBF was recorded to be 100%. Conclusion: The RDW was found to be highly sensitive and effective tool for early diagnosis of mild iron deficiency anaemia therefore; it is recommended that the RDW can be used as an effective tool for the diagnosis of iron deficiency anaemia in early stages, in a large number of samples at major hospitals thereby reducing manpower and time consumption.

Evaluation of the Effects of Electroplating Conditions on the Material Properties of Iron Cobalt Thick Films Using Design of Experiments

The effects of electroplating conditions on the material properties of iron cobalt thick film alloys were investigated. Samples were prepared from sixteen different combinations of electrodeposition conditions (temperature, current density, pH, and bath composition) using a binary design of experiments. A parametric study was done to investigate the effects of the process variable interactions on the magnetic and material properties The results obtained show that FeCo films with superior magnetic saturation, magnetic permeability, and low film stress are electroplated from an aqueous bath under the following deposition parameters: a high temperature, a low pH, low current density, and a high iron to cobalt ratio.

Ultrasensitive core for magnetooptical fluxgate magnetometer with high space resolution

New type of fluxgate magnetometer core on the basis of magnetooptical uniaxial Bi-substituted garnet film was designed, numerically modeled and investigated experimentally. Magnetooptical garnet film with weak magnetization exhibits extremely high sensitivity with relation to external magnetic field. High sensitivity is achieved by single domain wall displacement in film area restricted by potential barriers. High amplitude magnetooptical response was received from garnet film element with special shape in space region 20–200 mcm. Magnetic field value for sensitive element saturation and garnet film coercive field were found in the same range 20–200 /m. Used in fluxgate regime garnet film sensitive element can provide space resolution better 10 mcm with magnetic field sensitivity higher than that one of traditional fluxgate. Presented approach possesses to avoid temperature adjustment and inductive coils application in high sensitive magnetometers.

Adsorption of Crude Oil on Surfaces Using Quartz Crystal Microbalance with Dissipation (QCM-D) under Flow Conditions

Adsorption of crude oil on surfaces is successfully measured with a quartz crystal microbalance with dissipation (QCM-D) under flow conditions. The amounts and thicknesses of adsorbed films are determined with good accuracy using liquid loading corrections. Measurements are performed in solvents where the degree of asphaltene stability is high (toluene) and poor (n-alkanes and heptane/toluene mixtures). In toluene, Langmuir-type adsorption is recorded with saturation film thicknesses of 3−4 nm and limited desorption after rinsing. The size of adsorbing species is also determined at early times where adsorption is diffusion-controlled up to 3 wt % crude oil (or 835 ppm asphaltenes) in toluene. The primary asphaltene species that adsorb on the crystal surface are molecules with a diameter of 0.5−1.6 nm at 139−278 ppm asphaltenes and nanoaggregates with a diameter of 2.6−5.6 nm at 835 ppm asphaltenes in toluene. In n-alkanes (nC7, nC10, and nC12), saturation plateaus are not observed within the experimental time scale. Film thicknesses recorded after 3.5 h are all higher than those in toluene and increase with increasing n-alkane carbon number, mainly because of increasing polarity of aggregates. Atomic force microscopy (AFM) analyses reveal that the size of adsorbed aggregates decreases with n-alkane carbon number. Aging effects show that, with time, the adsorbed films become more rigid in toluene and more viscoelastic in n-alkanes. In heptane/toluene mixtures, a significant increase in the dissipation factor is observed close to the flocculation threshold. Adsorption on various surfaces from toluene shows a high affinity of asphaltenes to hydrophilic surfaces. On the other hand, asphaltenes are almost amorphous in n-alkanes. X-ray photoelectron spectroscopy (XPS) analyses of the adsorbed films confirm these observations.

Theoretical and experimental permeability spectra of nano-granular Co-Fe-Al-O films for GHz magnetoelastic device applications

The effects of the various parameters such as saturation magnetization, anisotropy field, film thickness and resistivity of soft magnetic thin films on the permeability spectra are investigated by using the Landau-Lifshitz-Gilbert equation. Both effects of eddy current loss and ferromagnetic resonance loss on the intrinsic permeability are taken into account to obtain the expression for the effective relative permeability. The calculated permeability spectra are in good agreement with experimental results for nano granular Co-Fe-Al-O thin films, even though only one fitting parameter, the damping constant, is used.

Relationship between saturation field and film texture in NiFeCo/Cu giant magnetoresistive multilayers

We investigated saturation fields and film textures of NiFeCo/Cu giant magnetoresistive multilayers with weak (1 0 0), weak (1 1 1) and strong (1 1 1) textures. The texture was changed by using various buffer layer materials. For 1 nm thick Cu layers, the saturation field of the multilayers was more than 100 kA/m, and not significantly changed by the texture of the multilayers. While for 2.3 nm thick Cu layers, the saturation field was changed by the texture of the multilayers. The saturation fields were 13.7 kA/m and about 2–3 kA/m for (1 0 0) and (1 1 1) texture, respectively.

Electrodeposition of ultrathin magnetic films of Fe and Co

We electrodeposited ultrathin magnetic Fe and Co films on Cu(001) crystals from an aqueous 0.3 M Na2SO4/(Fe or Co)SO4 electrolyte in a newly developed electrochemical cell. A deposition procedure of Fe from an organic electrolyte of propylene carbonate has been additionally developed to prevent the significant H2 evolution during the Fe deposition from an aqueous electrolyte. Fe films of more than 8 monolayer (ML) thickness show the easy magnetization axis in plane. The saturation magnetization correlates linearly with the film thickness. In the thickness range between 2 and 8 ML, the easy magnetization axis is in the [001] direction. No magnetization is observed in films with thickness of less than 2 ML. Co films show in-plane magnetization with square hysteresis loops and a linear correlation of the saturation magnetization and film thickness above 2 ML. The magnetization vanishes at coverages of less than 1.5 ML as known from molecular beam epitaxy grown films. The coercive field of the Co films varies approximately linearly from 0.9 mT at 2.5 ML to 25 mT at 51 ML film thickness.

Resting Energy Expenditure: Evolution During Antibiotic Treatment for Pulmonary Exacerbation in Cystic Fibrosis

To compare the changes in resting energy expenditure (REE) to concomitant changes in clinical status and pulmonary function in cystic fibrosis (CF) patients during treatment for acute pulmonary exacerbation. To determine if weight loss during exacerbation in CF is related to decreased calorie intake or increased energy needs. Measurements of REE, pulmonary function tests, oxygen saturation, respiratory rate, maximal inspiratory pressure (MIP), white blood cell count, chest x-ray films and attribution of clinical score (ACS) on admission, mid-hospitalization, and discharge. Anthropometric measurements on admission, assessment of dietary intake and nitrogen balance upon admission and prior to discharge. Thirteen CF patients admitted for treatment of acute pulmonary exacerbation with a mean age of 11.0 +/- 7.9 (SD) years. From admission to discharge, REE decreased from 44.5 +/- 9.0 to 33.8 +/- 8.5 kilocalorie (kcal)/kg/d (p < 0.003). Similarly, the ACS improved from 7.5 +/- 2.0 to 4.0 +/- 2.2 (p < 0.0001); the absolute neutrophil count decreased from 10,685 +/- 6,226/microliters to 6,363 +/- 168/microliters (p < 0.005); respiratory rate decreased from 32.6 +/- 6.2 to 25.0 +/- 3.7 breaths per minute (p < 0.01); and MIP increased from 77.5 +/- 20.0 to 90.0 +/- 20.4 cm H2O (p < 0.01). In parallel, less significant improvements occurred in pulmonary function tests, oxygen saturation and chest x-ray film scores. Calorie intake was 1,893 +/- 635 and 2,054 +/- 707 kcal/d on admission and discharge, respectively (p = NS); during hospitalization, weight increased from 23.6 +/- 10.1 to 25.7 +/- 10.1 kg (p < 0.005). While carbohydrate and fat content of the diet remained essentially unchanged, a significant increase in protein intake (3.15 +/- 0.92 to 3.5 +/- 0.81 g/kg/d [p < 0.05]) and in nitrogen balance (1.8 +/- 2.5 to 5.6 +/- 2.9 g of nitrogen per day [p < 0.05]) were observed. In acute CF, pulmonary exacerbation, changes in REE parallel those of clinical improvements and are more sensitive than pulmonary function tests and chest x-ray films as an objective clinical correlate. Increased metabolic requirements but not decreased dietary intake are the cause of weight loss in CF patients.

Transition noise properties in longitudinal thin-film media

Transition noise properties in longitudinal thin film media are studied by micromagnetic modeling. The mechanism for enhancement of transition noise at small bit intervals due to intertransition interaction is investigated. The noise dependence on the medium parameters, such as saturation magnetization and film thickness, is calculated. Reducing either the saturation magnetization or the film thickness yields a reduction of transition noise at low recording densities and a reduction of the noise enhancement at high recording densities. The effect of stress-induced longitudinal magnetic orientation is studied for an application of a uniaxial and spatial uniform compressive stress in the recording direction. The calculation shows that films with higher orientation ratio exhibit higher transition noise at small bit intervals. >