Saturation Trend Research Articles

Monthly physicochemical variation of tropical island groundwater of Pulau Bidong, south China sea

The groundwater of Pulau Bidong, Terengganu, Malaysia was investigated to monitor the quality of freshwater source. Groundwater samples were collected from five sampling stations from June 2016 to October 2016. Physical parameters such as temperature, specific conductivity, dissolved oxygen (DO), pH, salinity, and DO saturation were measured in-situ by using handheld device. Meanwhile, total suspended solid (TSS), total dissolved solid (TDS), nitrate (NO3−), nitrite (NO2−), ammonium (NH4+) and phosphate (PO43−) were also analysed. The inorganic nutrients of NO3−, NO2−, NH4+, and PO43− were ranged from 0.000 to 4.310 mg/L, 0.000–0.190 mg/L, 0.000–0.807 mg/L and 0.003–0.028 mg/L, respectively. The monthly trends of specific conductivity, DO, salinity, DO saturation, NH4, NO3 and NO2 demonstrated significant variation in June (the lowest rainfall) compared to other months. Correlation matrix revealed that temperature was associated with the specific conductivity, and NH4+ strongly correlated with DO, NO3− and NO2−. Nevertheless, there is a strong negative correlation between physicochemical parameters and monthly rainfall distribution. The physicochemical parameters were within the recommended safe limits suggested by the World Health Organization (WHO) and National Drinking Water Quality Standard (NDWQS) except for pH. Nevertheless, pH of water does not directly impact on the human health. Environmetrics analysis demonstrated that NO3− and PO43− significantly influenced the groundwater quality spatially. Furthermore, the temporal variation of groundwater quality was affected by pH and salinity. Overall, the groundwater sources from Pulau Bidong are considered safe to be used as drinking water. Notably, future studies are required for long-term monitoring to ensure the good quality of groundwaters from Pulau Bidong.

Machine-washable and breathable pressure sensors based on triboelectric nanogenerators enabled by textile technologies

Utilization of textile's triboelectric effect to realize the perception of pressure is of great interest for self-powered wearable electronics that integrate seamlessly with smart fabrics. However, the challenges associated with rational material/device designs based on conventional textile structures and the lack of understanding of the mechanical circumstances experienced by textile devices hamper the further advancement of this technology. Here, textile pressure sensors based on triboelectric nanogenerators (TENGs) with machine washability and excellent breathability are manufactured by using machines to interlace robust Cu-coated polyacrylonitrile (Cu-PAN) yarns and parylene coated Cu-PAN (parylene-Cu-PAN) yarns via multiple textile industry compatible technologies for the first time, simultaneously achieving devices with stitched, woven, and knitted structures. TENG-based pressure sensors with different textile structures are investigated under as-fabricated conditions and after machine washing, and a relation is proposed between textile structure and the key characteristics of the sensors. The material/device designs, mechanical circumstances, manufacturing methods, etc., will affect the sensitivity, linearity, saturation trend and washability of the obtained sensors. Finally, a smart textile glove with stitched pressure sensors is made to demonstrate grip posture detection in various circumstances.

Evaluation of dentists regulatory systems stress during the provision of dental care according to pulse oximetry data

To evaluate the status of individual hemodynamic parameters (HR) and respiratory indicators of dentists performing local anesthesia. Material and methods. In the period from April 2019 to December 2019 the determination of heart rate (Heart rate) and blood saturation at 120 doctors aged 25-55 years was performed. The value of blood saturation by non-invasive pulse oximeter technique: SpO2 measurement range 0-99%; heart rate range 18-300 beats per minute. The limit of 95-98% was considered normal. However, we consider it correct to note the introduction of an error of 0.1% due to the constant wearing of a dentist's tight polymer mask. All subjects were preliminarily determined by Robergs-Landvere formula: maximum heart rate (MF)=205.8-(0.685·age). Maximum HR limits for the groups of subjects were 185.6±3.1 beats per minute in the first group; 178.7±3.1 beats per minute in the second group; 171.5±3.4 beats per minute in the third group. In all groups the tendency to decrease blood saturation in case of pain appearance in patients during treatment against the background of block anesthesia, as well as during anesthesia on the mandible was determined. The definition of SpO2 showed a slight downward trend in blood saturation when pain occurs within normal parameters. Thus, the limit of changes in the index against the background of performed local anesthesia on the mandible was 95.2-96.1% and 96.3-96.6% on the maxilla. Measurement of arterial oxygen saturation in dentists showed a tendency for a slight decrease in this indicator within the normal range when the patient developed pain. Thus, the limit of changes in the indicator against the background of local anesthesia on the lower jaw was 95.2-96.1%, on the upper jaw - 96.3-96.6%.

Numerical simulation study on hydraulic fracture propagation in heavy oil reservoir with THM coupling

The aim of the study involves examining the effect of heavy oil viscosity on fracture geometry in detail by establishing a heavy oil fracturing model and conventional fracturing model based on thermal-hydraulic-mechanical (THM) coupled theory, Walther viscosity model, and K-D-R temperature model. The results show that temperature exhibits the most significant influence on the heavy oil viscosity while the influence of pressure is the least. The special viscosity distribution results in significant differences in pore pressure, oil saturation, and changing trends between these two models. In the heavy oil reservoir fracturing model, the thermal effect completely exceeds the influence of pore elasticity, and the values of the fracture length, width, and static pressure exceed those calculated in the conventional fracturing model. Thus, a comparison of the measured values indicates that the results obtained by considering viscosity as a function of temperature and pressure are more accurate. [Received: February 9, 2018; Accepted: August 8, 2018]

Numerical simulation study on hydraulic fracture propagation in heavy oil reservoir with THM coupling

The aim of the study involves examining the effect of heavy oil viscosity on fracture geometry in detail by establishing a heavy oil fracturing model and conventional fracturing model based on thermal-hydraulic-mechanical (THM) coupled theory, Walther viscosity model, and K-D-R temperature model. The results show that temperature exhibits the most significant influence on the heavy oil viscosity while the influence of pressure is the least. The special viscosity distribution results in significant differences in pore pressure, oil saturation, and changing trends between these two models. In the heavy oil reservoir fracturing model, the thermal effect completely exceeds the influence of pore elasticity, and the values of the fracture length, width, and static pressure exceed those calculated in the conventional fracturing model. Thus, a comparison of the measured values indicates that the results obtained by considering viscosity as a function of temperature and pressure are more accurate. [Received: February 9, 2018; Accepted: August 8, 2018]

Effects of simulated nitrogen deposition on soil microbial biomass and community function in subtropical evergreen broad-leaved forest

Aim of the study: The aim of this study was to examine the effects of a 5-year simulated nitrogen (N) deposition on soil microbial biomass carbon (MBC), nitrogen (MBN), microbial community activity and diversity in subtropical old-growth forest ecosystems.Area of study: The study was conducted in forest located at subtropical forest in Anhui, east China.Material and methods: Three blocks with three fully randomized plots of 20 m × 20 m with similar forest community and soil conditions were established. The site applied ammonium nitrate (NH4NO3) to simulate N deposition (50 and 100 kg N ha−1 year −1). From three depths (0–10, 10–20 and 20–30 cm), were collected over four seasons (December, March, June and September), and then measured by community-level physiological profiles (CLPPs).Main results: N addition had no significant effect on MBC and MBN. The spatiotemporal variations in MBC and MBN were controlled by seasonality and soil depth. Soil microbial activities and diversity in the growing season (June and September) were apparently higher than the dormant season (March and December), there were significantly lower diversity indices found following N addition in September. However, N addition enhanced microbial activities and increased diversity indices in the dormant season. Redundancy analysis showed that pH, soil moisture, NO3--N and total phosphorus were the most important factors controlling the spatial pattern of microbial metabolic activity.Research highlights: These results suggest that soil microbial community function is more easily influenced than microbial biomass. The site has a trend of P-limited or near-N saturation, and will threaten the whole forest ecosystem with the increasing duration of N addition.Keywords: Nitrogen deposition; Seasonality; Soil microbial biomass; Microbial community; Subtropical old-growth forest.

Decomposition products and formation path of C3F7CN/CO2 mixture with suspended discharge

A mixture of perfluoronitrile (C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sub> CN) and carbon dioxide (CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) has excellent insulation and environmental protection properties, and it is considered to have the potential to replace SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> gas. However, there are few studies on the decomposition products and formation reasons of C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sub> CN/CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> gas under partial discharge. In order to study the decomposition characteristics of C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sub> CN/CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> gas, suspension potential was used to simulate partial discharge. The experimental study on partial discharge decomposition of C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sub> CN/CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> gas was carried out. The variation of decomposition products with discharge time was qualitatively and quantitatively analyzed by gas chromatography-mass spectrometry (GC/MS). The results show that the decomposition products of suspension discharge of C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sub> CN/CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> are mainly CF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> , C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> , C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sub> , CF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> CN and an unknown product. The relative contents of C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> remain basically unchanged with the increase of discharge time. The relative contents of CF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> , C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sub> and unknown products show a non-linear growth trend with the increase of discharge time. The relative content of CF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> CN gas shows a saturation trend with the increase of discharge time. Finally, based on density functional theory (DFT), the formation paths of various products are analyzed.

Single-Step Synthesis of Vertically Aligned Carbon Nanotube Forest on Aluminium Foils.

Vertically aligned carbon nanotube (VACNT) forests are promising for supercapacitor electrodes, but their industrialisation requires a large-scale cost-effective synthesis process suitable to commercial aluminium (Al) foils, namely by operating at a low temperature (<660 °C). We show that Aerosol-Assisted Catalytic Chemical Vapour Deposition (CCVD), a single-step roll-to-roll compatible process, can be optimised to meet this industrial requirement. With ferrocene as a catalyst precursor, acetylene as a carbon source and Ar/H2 as a carrier gas, clean and dense forests of VACNTs of about 10 nm in diameter are obtained at 615 °C with a growth rate up to 5 µm/min. Such novel potentiality of this one-step CCVD process is at the state-of-the-art of the multi-step assisted CCVD processes. To produce thick samples, long synthesis durations are required, but growth saturation occurs that is not associated with a diffusion phenomenon of iron in aluminium substrate. Sequential syntheses show that the saturation trend fits a model of catalytic nanoparticle deactivation that can be limited by decreasing acetylene flow, thus obtaining sample thickness up to 200 µm. Cyclic voltammetry measurements on binder-free VACNT/Al electrodes show that the CNT surface is fully accessible to the ionic liquid electrolyte, even in these dense VACNT forests.

Nonmonotonic Effects of Salinity on Wettability Alteration and Two‐Phase Flow Dynamics in PDMS Micromodels

AbstractThe interaction between fluid‐fluid and solid‐fluid interfacial forces and surface roughness controls the wettability. The ionic strength is the most important factor that controls electrostatic forces. Thus, a modification of the ionic strength can potentially lead to a change of the wettability, as shown in recent experimental works related to low‐salinity waterflooding, which is an enhanced oil recovery technology. Despite the significant research published on this topic, for the first time, we present how a change of the ionic strength alters the wettability in a pore network micromodel made of silanized polydimethylsiloxane (PDMS). We visualized the invasion of brine in an elongated hydrophobic PDMS micromodel, initially saturated with Fluorinert. Under different injection rates and ionic strengths and using image processing, we quantified the contact angle distribution in the flow network, the recovery curve with time, the brine breakthrough time, and the temporal change of resident saturation. The results imply that there is an optimal range of salinity at which saturation change accelerates and the breakthrough saturation maximizes, which highlights the concept of optimal salinity in wettability alteration. Also, we observed a shift of the contact angle distribution toward a more water‐wet state. Given the nonmonotonic trend of the breakthrough saturation with brine salinity, as well as recovery time versus the ionic strength, we conclude that the induced surface roughness is not the primary drive behind the accelerated saturation change. Therefore, the recovery time difference can be primarily attributed to the local alterations of the wetting properties of the porous medium due to the change of the ionic strength.

Environment-Friendly and Efficient Gaseous Insulator as a Potential Alternative to SF6

Sulfur hexafluoride (SF6) is commonly used in electrical insulation networks due to its superior dielectric properties. However, it possesses a high Global Warming Potential (GWP) of 22,800 times compared to CO2 (at equal mass over a time span of 100 years) and a high atmospheric lifetime. This alarming metric prompted investigation for substitute gases with minor environmental influences. The overall objective of this research is to evaluate refrigerant R152a as a potential alternative for SF6 in electrical insulation systems. R152a gas has a significantly reduced value of GWP (140) and is a cheap insulation medium as compared to SF6. In this paper, dielectric breakdown testing of R152a and a mixture of CO2 with different concentrations have been tested. The dielectric strength of R152a/CO2 gas shows a saturated growth trend with increasing the gap difference, gas pressure and mixing ratio of R152a. Based on our experimental conditions, R152a/CO2 gas reveals good dielectric properties, and insulation performance can reach up to 96% of SF6. Finally, this work will bring a cost-effective and environment-friendly gaseous insulator for utility companies and power equipment manufacturers.

Use of micro-PIXE for elemental characterization and iron uptake evaluation in zebrafish larvae exposed to iron oxide nanoparticles

We report on the evaluation of iron content and biodistribution in zebrafish larvae (Danio rerio) exposed to dextran-coated superparamagnetic iron oxide nanoparticles (SPION-DX) using the micro-PIXE technique. We compare results of elemental 2D maps and Fe quantification obtained from two different sample preparation procedures: one using sagittal slices prepared by cryo-sectioning and another using entire dehydrated larvae. Independently of the preparation method used, the Fe content in the tissues of exposed animals is significantly higher than in the controls, but the increase is not proportional to the exposure level. In addition, 2D elemental maps show a somewhat homogeneous Fe distribution in the larvae, with some samples showing a slight enhancement in Fe content near the gut. From the PIXE data a curve correlating the exposure (nanoparticle concentration in the fish water) to the iron content in the body was obtained, which shows a saturation trend towards high exposure doses.

Oxygen saturation histogram monitoring to reduce death or retinopathy of prematurity: a quality improvement initiative.

Maintaining preterm infants within a goal oxygen saturation range challenges care providers. Through periodic assessment of saturation trends on infants' bedside histogram reports, our initiative aimed to (1) increase time spent at goal saturations and (2) reduce death or severe retinopathy of prematurity. The initiative integrated histogram monitoring into provider, respiratory, and nursing care. Achieved oxygen saturations, chart audits, and bedside histogram monitoring flowsheets provided process measures with the outcome measure of death or severe retinopathy of prematurity. In infants <29 weeks' gestation (n = 518), the rate of death or severe retinopathy of prematurity prior to hospital discharge decreased from 32.1% to 18.0%. Time at goal saturations (90-95%) increased from 48.7% to 57.6%. In infants born at <29 weeks' gestation, periodic, multidisciplinary oxygen saturation histogram monitoring improved time at goal saturations and was associated with a reduction in death or severe retinopathy of prematurity.

PETROPHYSICAL AND ROCK PHYSICS ANALYSES FOR CHARACTERIZATION OF COMPLEX SANDS IN DEEPWATER NIGER DELTA, NIGERIA

Characterization of complex sand reservoirs in deepwater of Niger Delta was carried out through petrophysical and rock physics evaluation of well log data from three wells. Petrophysical analysis to determine clay volume, porosity, lithologies, and hydrocarbon saturation were made. Rock physics was studied in a velocity-porosity plane to analyze the influence of depositional and diagenetic features on the reservoirs. Cross-plots of different elastic parameters, using linear regression and cluster analysis, were generated for lithologic and fluid fill identification and to differentiate between the hydrocarbon bearing sands, brine sands, and shale. Variance attribute was extracted on seismic time slice in order to image the complex sand distribution in the area. Three reservoirs of turbidite origin were identified within the upper fan to lower fan area. Petrophysical results revealed gas bearing reservoir units with less than 20% shale volume and porosity of 25-31%. Lambda-Mu-Rho (LMR) cross-plots for the reservoirs show gas saturated data cloud and trend. Ratio-Difference (R-D) cluster analysis of elastic rock properties shows a distinct trend and data cloud that represents lithofacies units and fluid fills. The study concludes that the reservoirs simulated contact cement and friable models with properties that ranged from highly porous, well sorted and poorly consolidated sand to fairly sorted and highly cemented sands. The results provide a model that increases the possibility of finding reservoir sand while mitigating the risk involved in finding hydrocarbons. Keywords: Rock Physics, Petrophysics, Deepwater, Reservoir, Niger Delta, Cross-plot http://doi.org/10.35180/gse-2019-0009

Analysis of the effect of system parameters for combined nonlinear cable elongation characteristics in CDPR

The polymer cable is a widely used material in the cable-driven parallel robot (CDPR) system because of its many advantages such as high sensitivity, large workspace and so on. However, the accurate control of CDPR is not easy because of complicated response of the cable. In our previous study, the integrated cable model was derived. Based on the model, parametric studies were progressed in this paper. While operating CDPR, various parameters such as length, applied tension, and tensile rate can be changed and dominantly affect the dynamics of CDPR. For this reason, parametric study was based on these parameters. In this investigation, dynamic creep, hardening factor and short-term recovery were saturated as processing cyclic load. Each saturation rate was dominantly influenced by cable length and applied tension. As the tensile rate was increased, the dynamic creep was decreased. The hysteresis was the characteristic combining all of dynamics. So, the hysteresis also had saturation trends. When the exerted tension was decreased, the length of cable could be reduced or elongated because the creep and recovery occur at the same time.

Examination of downward hydrocarbon charge within the Bakken-Three Forks petroleum system – Williston Basin, North America

Abstract The Bakken and Three Forks Formations of the Williston Basin have been targeted by over 10,000 unconventional style wells (horizontal drilling coupled with hydraulic fracturing). Exploration and developmental drilling initially focused on the Middle Bakken but later expanded into the underlying upper Three Forks (located directly below the Bakken) and eventually the middle and lower Three Forks, which are positioned 10s to 100 + feet below the Bakken. Hydrocarbons (oil and associated gas) within both formations are believed to be sourced from the upper and lower Bakken shale members, which are both highly organic-rich (>10% TOC), thermally mature petroleum source beds. However, minimal literature exists examining the relationship between hydrocarbons generated by the lower Bakken shale and expelled downward into the various reservoirs of the Three Forks. Core-plug oil and water saturation data from 65 partial to complete Three Forks cores were utilized to map out fluid saturation trends within the upper, middle, and lower Three Forks. Over 500 core chip analyses from 52 cores were used to spatially delineate the present day average hydrogen index (thermal maturity) of the lower Bakken shale while a lower shale isopach map was created from wireline logs of 240 wells. Lastly, the geochemical and standard core-plug data from four complete Bakken-Three Forks cores were used to calculate and compare the volumetric amount of oil generated and expelled from the lower Bakken shale with the original oil in place (OOIP) of the entire Three Forks section. The results show a strong spatial relationship between increased thickness-thermally maturity of the lower Bakken shale and increased core-plug oil saturations across the upper to middle Three Forks members, and a similar, but less pronounced relationship with the lower Three Forks. The calculated lower Bakken shale expelled oil volumes ranged from 13 to 51 million barrels of oil (MMBO) per section (640 acres) which overall equaled to exceeded the OOIP of the entire Three Forks section (9–25 MMBO/section). These spatial and volumetric relationships indicate that local hydrocarbon generation and expulsion from the lower Bakken shale is the primary control for hydrocarbon charge within the underlying Three Forks Formation, where in some locations hydrocarbons have been pushed downwards 200 + ft. Understanding downward hydrocarbon charge has implications in exploring for and developing hydrocarbon resources within the Bakken-Three Forks as well as numerous other unconventional petroleum systems.

Surface oxidation model in plasma enhanced atomic layer deposition for silicon oxide films including various aminosilane precursors

In this study, a surface oxidation model for the plasma enhanced atomic layer deposition process for silicon oxide films formed by the combination of aminosilane with Ar/O2 plasma is proposed. After the discussion of the dominant oxidation pathways involving both reactive species generation and reaction energy barriers, the authors develop a surface oxidation model and compare it with experimental deposition results. From plasma simulation results, they confirmed two dominant species generated by Ar/O2 plasma; triplet oxygen atom (3O) and singlet oxygen molecule (1O2). The authors then compared the reaction energy barrier along the oxidation pathways for these oxidation species and the corresponding surface terminations by using density functional theory calculations. The calculated activation barriers were negligible in the oxidation paths with 3O, but not in the ones with 1O2. These results support that oxidation by 3O was dominant, especially at low substrate temperatures. The authors suggest a surface oxidation model having two kinds of surface terminations; hydrogen terminations (Si–H) and amino ligand terminations (Si–R). This model can explain the experimental saturation curve for surface oxidation against plasma irradiation time as a function of substrate temperature. The authors confirmed that saturation trends observed with various aminosilane precursors can successfully be explained by their differing ratios of Si–H and Si–R bonds present prior to oxidation.In this study, a surface oxidation model for the plasma enhanced atomic layer deposition process for silicon oxide films formed by the combination of aminosilane with Ar/O2 plasma is proposed. After the discussion of the dominant oxidation pathways involving both reactive species generation and reaction energy barriers, the authors develop a surface oxidation model and compare it with experimental deposition results. From plasma simulation results, they confirmed two dominant species generated by Ar/O2 plasma; triplet oxygen atom (3O) and singlet oxygen molecule (1O2). The authors then compared the reaction energy barrier along the oxidation pathways for these oxidation species and the corresponding surface terminations by using density functional theory calculations. The calculated activation barriers were negligible in the oxidation paths with 3O, but not in the ones with 1O2. These results support that oxidation by 3O was dominant, especially at low substrate temperatures. The authors suggest a surface...

Surface oxidation model in plasma enhanced atomic layer deposition for silicon oxide films including various aminosilane precursors

In this study, a surface oxidation model for the plasma enhanced atomic layer deposition process for silicon oxide films formed by the combination of aminosilane with Ar/O2 plasma is proposed. After the discussion of the dominant oxidation pathways involving both reactive species generation and reaction energy barriers, the authors develop a surface oxidation model and compare it with experimental deposition results. From plasma simulation results, they confirmed two dominant species generated by Ar/O2 plasma; triplet oxygen atom (3O) and singlet oxygen molecule (1O2). The authors then compared the reaction energy barrier along the oxidation pathways for these oxidation species and the corresponding surface terminations by using density functional theory calculations. The calculated activation barriers were negligible in the oxidation paths with 3O, but not in the ones with 1O2. These results support that oxidation by 3O was dominant, especially at low substrate temperatures. The authors suggest a surface oxidation model having two kinds of surface terminations; hydrogen terminations (Si–H) and amino ligand terminations (Si–R). This model can explain the experimental saturation curve for surface oxidation against plasma irradiation time as a function of substrate temperature. The authors confirmed that saturation trends observed with various aminosilane precursors can successfully be explained by their differing ratios of Si–H and Si–R bonds present prior to oxidation.

Atom-subjected optical dipole force exerted by femtosecond laser field

&lt;sec&gt; In 2011, Kumar et al. (2011 &lt;i&gt;Phys. Rev. A&lt;/i&gt; &lt;b&gt;84&lt;/b&gt; 043402) studied the light force acting on a beam of neutral two-level atoms superimposed on a few-cycle-pulse Gaussian laser field under both resonant and off-resonant conditions by solving the optical Bloch equation beyond the rotating-wave approximation, and they found that under resonant condition the transverse component of the light force shows oscillatory behavior but vanishes when a time average is taken, and the time averaged longitudinal force is nonzero only when the Rabi frequency is smaller than the resonant frequency and vanishes when the Rabi frequency is equal to or larger than the resonant frequency.&lt;/sec&gt;&lt;sec&gt; In this paper, we investigate further the strong nonlinear optical interaction between a two-level atomic system and a femtosecond Gaussian laser pulse by solving numerically the full-wave optical Bloch equations through using the predictor-corrector method. It is found that the light forces and the light potentials are sensitive to the value of the Rabi frequency and the detuning of the laser field. Under the resonant condition, the instant light forces induced by the femtosecond laser pulse change their signs as a function of time. The instant longitudinal light force changes its sign at twice the Rabi frequency, while the instant transverse light force changes its sign at twice the light carrier-wave frequency. However, none of the time-averaged light forces is zero, showing periodical oscillation characters as a function of Rabi frequency. Both of the time-averaged longitudinal and transverse light forces oscillate at the Rabi frequency corresponding to the pulse area of 2&lt;inline-formula&gt;&lt;tex-math id="Z-20190110084840-1"&gt;\begin{document}${\text{π}}$\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20182016-e_Z-20190110084840-1.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20182016-e_Z-20190110084840-1.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt;. The time-averaged transverse light force shows also a trend of enhancement with Rabi frequency increasing, and the time-averaged longitudinal light force shows also a saturation trend with the increase of the Rabi frequency. The optical potential depends strongly on the detuning. It changes gradually from repulsive potential to attractive potential when the detuning defined here changes from negative to positive detuning. When the field is nearly resonant, the optical potential then oscillates between repulsive and attractive potentials. Therefore, neutral atoms can be focused, defocused, trapped, splitted or steered by the femtosecond laser field with appropriate detuning and Rabi frequency. &lt;/sec&gt;

Experimental Study on Power Frequency Breakdown Characteristics of C4F7N/CO2 Gas Mixture Under Quasi-Homogeneous Electric Field

As a new environmental-friendly gas insulating medium, perfluoroisobutyronitrile (C 4 F 7 N) has been widely concerned in recent years due to its relatively low global warming potential and excellent dielectric strength, which has the potential to replace the most greenhouse gas, sulfur hexafluoride(SF 6 ). However, there are a few systematic studies on the influence of gas pressure and mixing ratio on the dielectric strength of C 4 F 7 N/CO 2 gas mixture at present. In this paper, the power frequency breakdown characteristics of C 4 F 7 N/CO 2 gas mixture under different pressure and mixing ratio conditions were tested using the gas insulation performance test platform. The optimal mixing ratio and pressure range of C 4 F 7 N/CO 2 gas mixture for engineering application were also discussed. It is found that the breakdown voltages of C 4 F 7 N/CO 2 gas mixture show a saturated growth trend with gas pressure and mixing ratio. The breakdown voltage of the gas mixture with 10% C 4 F 7 N can reach 80% of pure SF 6 under the same condition. The insulation performance of the gas mixture with 20% C 4 F 7 N can reach more than 95% of pure SF 6 . Relevant results indicate that the gas mixture with 4%-12% C 4 F 7 N has the potential to be applied to high-voltage gas-insulated equipment.

Ultrafast Carrier Dynamics and Terahertz Photoconductivity of Mixed-Cation and Lead Mixed-Halide Hybrid Perovskites**Supported by the National Natural Science Foundation of China under Grant Nos 11604202, 11674213, 61735010 and 51603119, the Young Eastern Scholar under Grant Nos QD2015020 and QD2016027, the Shanghai Rising-Star Program under Grant No 18QA1401700, the ‘Chen Guang’ Project under Grant Nos 16CG45 and 16CG46, the Shanghai Municipal

Using time-dependent terahertz spectroscopy, we investigate the role of mixed-cation and mixed-halide on the ultrafast photoconductivity dynamics of two different methylammonium (MA) lead-iodide perovskite thin films. It is found that the dynamics of conductivity after photoexcitation reveals significant correlation on the microscopy crystalline features of the samples. Our results show that mixed-cation and lead mixed-halide affect the charge carrier dynamics of the lead-iodide perovskites. In the (5-AVA)0.05(MA)0.95PbI2.95Cl0.05/spiro thin film, we observe a much weaker saturation trend of the initial photoconductivity with high excitation fluence, which is attributed to the combined effect of sequential charge carrier generation, transfer, cooling and polaron formation.