Solution Bi Research Articles

Stable lead free perovskite solar cells based on bismuth doped perovskite materials

The inclusion of lead in the Champion perovskite material MAPbI3 is a detrimental factor in the commercialization of lead based perovskite solar cells. This is mainly due to the toxicity of lead and also due to degradation of MAPbI3 in ambient condition into hazardous chemicals which are toxic to the environment [1]. Due to these factors, though the Hybrid Organic Inorganic Lead based PSCs exhibit excellent photovoltaic effect and photo conversion efficiency (PCE), yet numerous theoretical and experimental studies have been done to replace lead with suitable elements such as Sn, Ge, Bi etc. This research work focusses on replacing Pb from MAPbI3, with different wt% of Bi such as 1%, 2%, 4% and 8% and analyzing its effect on the stability and efficiency of the PSC. These solutions of Bi doped perovskite are coated on the FTOs and are fabricated under room ambient condition in the sandwich structure. The results exhibit lower efficiency of Bismuth doped PSCs but it shows remarkable stability comparable to that of MAPbI3.

Effect of Bi on the Tensile and Viscoplastic Behavior of Sn-Ag-Cu-Bi Alloys Used for Microelectronics Applications

Sn-Ag-Cu-Bi (SAC-Bi) alloys are gaining popularity as a potential replacement for current lead-free solder alloys in microelectronic packages. In this study, the tensile and viscoplastic behaviors of eight SAC-Bi alloys with 0, 1 wt.%, 2 wt.%, and 3 wt.% Bi content were investigated. The samples of these eight alloys were cast, aged at room temperature, 75 °C and 125 °C, and tensile-tested at rates of 0.1/s, 0.01/s, and 0.001/s in ambient and elevated temperature environments to facilitate the quantification of viscoplasticity using the Anand viscoplastic model. The Anand parameters of all eight alloys in the as-cast and aged conditions were determined. Tensile strength was found to increase with the addition of Bi. Additionally, alloys containing 2 and 3 wt.% Bi showed a 5 to 10% increase in tensile strength after isothermal aging of 90 days at 125 °C. On the contrary, the tensile strength of alloys with up to 1 wt.% Bi decreased by 22 to 48% after such aging. Using a Scanning Electron Microscope (SEM) and energy dispersive spectroscopy (EDS), the microstructure of the alloys was characterized. The aging-induced property changes in the samples were correlated to strengthening by Bi solute atoms for alloys with 1 wt.% Bi and the formation of Bi precipitation for alloys with 2 wt.% and 3 wt.% Bi.

Improving business efficiency based on the capabilities of BUSINESS EFFICIENCY tools

the purpose of this article is to conduct a comparative analysis of BI solutions that can be used to replace common foreign systems such as Power BI, Tableau and Qlik. Due to the practical orientation and active development of this subject area, mainly Russian-language articles of news and analytical agencies are used as analysis materials. The following methods were used to conduct the study: bibliographic analysis, testing, comparative analysis. As a result, a table was compiled reflecting the presence or absence of the most significant parameters when choosing a BI-system. In conclusion, it is worth noting that at the moment there is no universal solution, each company must rely on its own constraints and take into account the existing IT infrastructure.

Implementation of Cross-Functional BI Solutions for Global Consumer Brands

Implementation of Cross-Functional BI Solutions for Global Consumer Brands

Challenging Fabrication and Characterization of a New Ferroelectric Solid-Solution Composition 0.30Bi(Cu1/2Ti1/2)O3 – 0.70PbTiO3

In this paper, an unexplored solid solution (1-x)Bi(Cu1/2Ti1/2)O3-(x)PbTiO3 has been synthesized and characterized for its crystal structure, dielectric and ferroelectric properties aimed at a selected composition, i.e., 0.30 Bi(Cu1/2Ti1/2)O3-0.70PbTiO3. The paper unveils the different synthesis approaches to achieve pure-phase in Pb-based perovskite-structured materials that are prone to produce impurities during synthesis. The Rietveld refinement of the XRD pattern confirms a tetragonal crystal structure (P4mm) of the composition. The ferroelectric properties of the as-prepared composition are also discussed using P-E hysteresis and PUND characteristics. The composition shows a high Tc (480 °C) and low dielectric losses, making it suitable for high-temperature applications.

Experimental determination of solid-liquid interface energy for para- and diamagnetic solid solution in equilibrium with eutectic liquid under a high magnetic field

The solid-liquid interface energy (SLIE) of the Al-Cu and Bi-Cd systems under a high magnetic field (HMF) has been experimentally determined by a Bridgeman-type directional solidification furnace. The equilibrated grain boundary groove shapes for the paramagnetic solid α-Al solution and the diamagnetic solid Bi solution in equilibrium with the eutectic liquid under various HMFs were observed in Al-15.3at%Cu alloy and Bi-50at%Cd alloy. It can be found that the profiles of grain boundary grooves changed significantly under the action of the HMF. The Gibbs-Thomson coefficient and the SLIE for the solid α-Al and solid Bi solution in equilibrium with the eutectic liquid under various HMFs were obtained from obtained grain boundary groove shapes. The results show that the SLIE of the Al-Cu and Bi-Cd alloys increase and decrease under an HMF, respectively. The interaction theory of magnetic dipoles induced by an HMF can be responsible for the above experimental phenomena. Additionally, the results of the differential thermal analysis (DTA) and theoretical analysis indicate that the undercooling of the Al-15.3at%Cu and Bi-50at%Cd alloys increase and decrease under the influence of an HMF, respectively, which is ascribed to the existence of HMF-induced interface energy.

Simultaneous Measurement of Trace Levels of Hg, As, Sb, and Bi in Coastal Seawater with a Multichannel Chemical Vapor Generation Atomic Fluorescence Spectrometer.

Trace levels of Hg, As, Sb, and Bi in coastal seawater have been simultaneously detected by a laboratory-built multichannel chemical vapor generation coupled to an atomic fluorescence spectrometer. The system was configured with a built-in electrochemical H2 generator as the fuel supplier to replace chemical H2 produced by the oxidation of potassium borohydride under acidic conditions in traditional instruments. The electrochemical H2 generator not only isolated the atomization process from the chemical vapor injection process but also improved the stability of atomization, excitation, and fluorescence emission in the hydrogen flame, making it easier to optimize conditions for CVG while introducing evaporating multielement vapors. Calibrations were obtained using a mixed standard solution of Hg(II), As(III), Sb(III), and Bi(III). The addition of KBr to a 3% (v/v) HCl solution was selected as the preservative to ensure the stability of 0.10 μg/L Hg(II) in a multielement standard solution for at least 15 days while also preserving μg/L levels of As(III), Sb(III), and Bi(III) stable. The method detection limits (LOD, 3σ) were 0.001, 0.015, 0.010, and 0.005 μg/L for Hg, As, Sb, and Bi, respectively. The relative standard deviations (RSD, n = 7) of the standard spiked seawater samples were 3.2% (0.020 μg/L Hg), 1.2% (0.50 μg/L As), 1.0% (0.50 μg/L Sb), and 3.5% (0.050 μg/L Bi), respectively. The recoveries of seawater samples spiked with different salinities were in the range of 84.5%(Sb)-114%(Hg). The system has been successfully applied to the simultaneous analysis of the four elements in the seawater samples collected from Xiamen Bay, Southeast China.

Two Noncentrosymmetric Bismuth Phosphates: Rational Design Synthesis and Optical Properties.

Developing strategies to rational design noncentrosymmetric structure still attract much interest for their applications in nonlinear optical and piezoelectric materials. Two noncentrosymmetric (NCS) alkaline earth metal bismuth phosphates have been successfully achieved via partial replacement of Bi3+ with Ca2+ or Sr2+ ions. BiCa(H0.5PO4)2 (designated as CaBiPO) and BiSr(H0.5PO4)2 (designated as SrBiPO), together with their solid solution Bi(Sr1-xCax)(H0.5PO4)2 (0 < x ≤ 0.5), crystallize in the NCS space group C2. Both CaBiPO and SrBiPO exhibit ultraviolet nonlinear optical (NLO) properties, and their second-harmonic generation effects belong to type-II phase matching. Meanwhile, they could also act as photoluminescence hosts in which the Eu3+-doping samples SrBiPO:xEu3+ (x = 0.02-0.2) emit orange light. The effect of different radius ions on the derivative structures and the structure-NLO property relationship has also been discussed in detail.

Hot tear cracks on the suppression of Sn–Bi alloy for low-temperature assembly

PurposeIn the electronic assembly industry, low-temperature soldering holds great potential to be used in surface mounting technology. Tin–bismuth (Sn–Bi) eutectic alloys are lead-free solders applied in consumer electronics because of their low melting point, high strength and low cost. This paper aims to investigate how to address the problem of hot tear crack formation during Sn–Bi low-temperature solder (LTS) in the mass production of consumer electronics.Design/methodology/approachThis paper explored the development of hot tear cracks during Sn–Bi soldering in the fabrication of flip chip ball grid arrays. Experiments were designed to simulate various conditions encountered in Sn–Bi soldering. Quantitative analysis was conducted on the number of hot tear cracks observed in different alloy compositions and solder volumes to explore the primary cause of hot tear cracks and possible methods to suppress crack formation.FindingsHot tear cracks existed in Sn–Bi solders with different bismuth (Bi) contents, but increasing the solder volume reduced the number of hot tear cracks. Experiments were designed to test the degree of chip transient thermal warpage with temperature change, and, according to the results, glue was dispensed in specific areas to reduce chip warpage deformation. Finally, the results of combined process experiments pointed to an effective method of low-temperature soldering to suppress hot tear cracks.Research limitations/implicationsThe study focuses on Sn–Bi solders only without other solder pastes such as SAC305 or Sn–Zn series.Practical implicationsWith the growing popularity of smart electronics, especially in intelligent terminals, new energy vehicles electronics, solar photovoltaic and other field, there will be more and more demand for low- temperature, energy-saving, lead-free solders. Therefore, this study will help the industry to roll out LTS (Sn–Bi) solutions rapidly.Social implicationsIn the long term, lean and green manufacturing is expected to be essential for maintaining an advanced manufacturing industry across the world. Developing new LTSs and soldering processes is the most effective, direct solution for energy conservation and emission mitigation. With the growing popularity of smart electronics, especially in intelligent terminals, new energy vehicles and solar photovoltaics, there would be an increased demand for low-temperature, energy-saving, lead-free techniques.Originality/valueAlthough there are many methods that can be used to suppress hot tear cracks, there is little research on how to control the hot tear cracks caused by the low-temperature soldering of Sn–Bi in laptop applications. The authors studied the hot tear cracks that developed during the world’s first mass production of 50 million personal laptops based on low-temperature Sn–Bi alloy solder pastes. By controlling the Bi content, redesigning the solder paste printing process (e.g. through a printer’s stencil) and adding dispensing processes, the authors obtained reliable and stable experimental data and conclusions.

Synthesis and Characterization of a New Ferroelectric with Low Lead Content, a High Curie Temperature, and a High Piezoelectric Response

AbstractA new solid solution (1−x)Bi(Fe2/8Ti3/8Mg3/8)O3–(x)PbTiO3 (BFTM‐PT) is synthesized and the electromechanical properties are measured. This system is defined as a low‐lead material with ferroelectric/piezoelectric behavior and a morphotropic phase boundary (MPB) that leads to enhanced properties. The MPB is located between x = 0.30 and 0.35 and coincides with a structural phase transition and a sharp increase in the piezoelectric response. The system demonstrates ferroelectric hysteresis where x = 0.325 displays the best properties with a maximum polarization of 39 µC cm−2 and a remnant polarization of 26 µC cm−2. The range of compositions has high Curie temperature (Tc), ranging from 625–650 °C. Materials with a Tc above 400 °C typically have a low d33 of &lt;50 pC N−1 at room temperature. However, BFTM‐PT has a higher d33 that most other compositions with a Tc in this range, with the highest being 145 pC N−1 for x = 0.375. The d33 drops off above 100 °C, but doping studies can be done in the future to stabilize the piezoelectric response at higher temperatures. These outstanding properties open the possibility of new transducer applications, in particular ones requiring high temperature and high power.

Implementation of Business Intelligence Solution for United Airlines

US Airline is recognized as the world's largest airline, with a massive number of daily departures completed and a combined fleet of over 2700 aircraft. US Airlines have carried major 18 airlines, categorized as mainline, regional, and freight airlines. United Airline is one of the major airlines in the US after American Airlines and Delta Airlines in the world. Today, companies received as much feedback from their customers. Customers can share their opinion and emotion through social media platforms, such as Twitter. Thus, collecting and understanding customer’s opinion become the key benefits for the aviation industry to get actionable insights while increasing their competitiveness. Such insights are useful in planning and execution to increase the relationship with customers. Thus, this study was conducted to analyze customer’s feedback in different airlines to discover actionable insights that increase the competitiveness of United Airline. The analysis result will be visualized on Tableau dashboards and BI solutions will be provided. By implementing the BI solutions, United Airline can make accurate decisions and define next strategies by identifying those positive and negative references. Thus, United Airline can improve the quality of their service, enhance customers loyalty, and boost business profitability.

Reaction of Bi(NO3)3 with quinoxaline in the presence of HI. Synthesis of 5,6,7,8-tetranitro-1,2,3,4-tetrahydroquinoxaline-2,3-diol by serendipity: Crystal structure, Hirshfeld and optical study of a novel energetic compound

Treatment of an acetone solution of Bi(NO3)3 with quinoxaline (Qx) in the presence of hydroiodic acid produces in moderate yield the crystallographically characterized 1D-polymeric salt-like iodobismutate [(Qx-H+)BiI4]n (1), whose negative charge is balanced by mono-protonated quinoxalinium counterions. The main product is an unusual tetra(nitrated) quinoxaline derivative, namely 5,6,7,8-tetranitro-1,2,3,4-tetrahydroquinoxaline-2,3-diol (2), which was formed accidently under mild reaction conditions. The molecular structure of this organic compound 2 was determined by single-crystal X-ray diffraction and its strong intermolecular interactions giving rise to a supramolecular three-dimensional network were assessed by IR spectroscopy and a Hirshfeld surface analysis. Structural analysis reveals that the crystal structure is supported essentially by O‒H···O and N‒H···O intermolecular hydrogen bonds and additionally stabilized by N‒O···π interactions. The ground-state molecular structure of this novel organic heterocycle has been optimized by DFT calculation. The optical band gap, caused by intramolecular charge transfer (ICT) from the 1,2,3,4-tetrahydroquinoxaline-2,3-diol fragment to the nitro groups, has been estimated to be 2.04 eV. High density, positive heat of formation and very good thermal stability according to thermal analysis by TGA, DTA and DSC characterize tetranitro compound 2 as energetic material.

Electrodeposition of bismuth at a graphene modified carbon electrode and its application as an easily regenerated sensor for the electrochemical determination of the antimicrobial drug metronidazole

Metronidazole is a well-known antimicrobial drug that belongs to the nitroimidazole family of antibiotics. It has been widely used in the treatment of infections, but its accumulation in aquatic environments is an emerging concern. In this study a glassy carbon electrode was modified with graphene (Gr) nanoplatelets and bismuth. Both the Gr and Bi were electrochemically deposited onto the glassy carbon and the modified electrode was employed in the electrochemical detection of metronidazole. At the modified electrode, the reduction of metronidazole was found to be an adsorption-controlled reaction. The optimised sensor, which was fabricated within 6 min, exhibited good selectivity in the presence of various inorganic and organic compounds, good recovery in tap water, and exhibited a linear calibration curve extending from 0.005 to 260 μM, with a limit of detection of 0.9 nM. The sensor was easily regenerated through the simple oxidation of the Bi deposit followed by a 100 s reduction period in the Bi(III) solution to give a newly generated surface. Good reproducibility was achieved using this simple regeneration approach.

Synthesis of Bi/Sr doped zinc sulphide by spray pyrolysis technique: Effects of doping tempertures on solar cell application

With the aim of determining the best synthesizing substrate temperature that will improve the optical properties of Bi/Sr doped ZnS thin film, spray coated Bi/Sr doped ZnS thin films were deposited at a varying glass substrate temperature of 200 °C–350 °C using an interval of 50 °C. A constant volume of 40 ml of precursor solution was created by adding 10 ml of each of the following solutions: 0.045 M solution of zinc acetate dihydrate C4H6O4Zn.2H2, 0.1 M solution of thioacetamide CH3CSNH2, 0.02 M solution of bismuth nitrate Bi(NO3)3.5H2O, and 0.07 M solution of Strontium hydroxide Sr(OH).2. UV–Visible Spectrophotometry, scanning electron microscope (SEM), EDX, X-ray diffraction (XRD), photoluminescence, and Fourier transform infrared (FTIR) were all used to investigate the samples. 53.84 and 193.26% increment in carrier concentration and mobility, a 36.36% and 17.77% reduction in resistivity, and a band gap were obtained at a doping temperature of 300 °C. An open-circuit voltage (Voc) of 0.30 V and a power conversion efficiency of 0.58% were achieved. It was established that a doping temperature of 300 °C on Bi/Sr doped ZnS thin films can be used to lower the band gap of ZnS for solar cell applications.

Enhanced energy storage performance of 0.88(0.65Bi0.5Na0.5TiO3-0.35SrTiO3)-0.12Bi(Mg0.5Hf0.5)O3 lead-free relaxor ceramic by composition design strategy

Dielectric ceramic capacitors with high energy density are one of the great bright energy storage devices. Here, the Bi0.5Na0.5TiO3, 0.75Bi0.5Na0.5TiO3-0.25SrTiO3, 0.65Bi0.5Na0.5TiO3-0.35SrTiO3 and 0.88(0.65Bi0.5Na0.5TiO3-0.35SrTiO3)-0.12Bi(Mg0.5Hf0.5)O3, (abbreviated as BNT, BNT-25ST, BNT-35ST and BNST-BMH, respectively) ceramics were produced by solid state sintering method. The influence of solid solution of SrTiO3 and Bi(Mg0.5Hf0.5)O3 doping in Bi0.5Na0.5TiO3 on crystal structure, microstructure, electrical and energy storage performance were evaluated systematically. By optimizing ceramics composition, high breakdown field and slim hysteresis loops were simultaneously realized due to enhanced band gap, refined grain size and nano-domains formed, which can be verified by the transmission electron microscope (TEM), piezoelectric force microscope (PFM) and ultraviolet–visible spectrum. Therefore, an ultrahigh recoverable energy density of 5.59 J/cm3 with brilliant efficiency of 85.3% is realized in BNST-BMH ceramic. Besides, the BNST-BMH also exhibits prominent temperature stability at 20–140 °C, superior fatigue resistance beyond 105 cycles and outstanding frequency stability at 1–200 Hz. Our work offers a novel way for designing dielectric capacitors and also proves that BNST-BMH is indeed a great hopeful dielectric energy storage material in pulse power electronics.

Reply to the 'Comment on "Structural, electrical and multiferroic characteristics of lead-free multiferroic: Bi(Co0.5Ti0.5)O3-BiFeO3 solid solution"' by P. E. Tomaszewski, RSC Adv., 2022, 12, DOI: 10.1039/D1RA08415A.

The cobalt and titanium modified BiFeO3 [i.e., Bi(Co0.40Ti0.40Fe0.20)O3; referred to as BCTF80/20] solid solution was synthesized via a simple and cost effective solid-state technique, and numerous sets of studies (structural, elemental, electrical, leakage current, multiferroic and other properties) were carried out and reported. The basic structural symmetry was investigated and phase identification of the prepared samples was carried out by analyzing powder X-ray diffraction data through the widely used "POWDMULT" software. From the XRD pattern [Fig. 2(a) of RSC Adv., 2018, 8, 36939], it is clear that almost all the reflection peaks (including those that appear to be split) have been indexed to a single phase (based on the best agreement between experimental and calculated interplanar distances and minimum standard deviation) system using the above software. The lattice parameters, average crystallite size, cell volume, and micro-strain value are strongly affected by the addition of Co and Ti into the bismuth ferrite. The significant enhancement of various parameter (i.e., electrical, multiferroic and so on) values of BCTF80/20 ceramics may make them promising candidates for the development of new generation electronic devices.

Fast Scalable Synthetic Methodology to Prepare Nanoflower‐Shaped Bi/BiOClxBr1−x Heterojunction for Efficient Immobilized Photocatalytic Reactors under Visible Light Irradiation

AbstractThe metal/photocatalyst heterojunction has demonstrated an excellent capability for pollutant degradation under visible light irradiation. In this study, for the first time, highly stable colloidal dispersions of Bi/BiOClxBr1−x heterojunction with an exposed (001) facet are successfully prepared from inorganic simple salts using low‐frequency ultrasound irradiation (LFUI) at ambient conditions without further post‐treatment. The colloidal dispersion series of Bi/BiOClxBr1−x heterojunction (x = 0, 0.2, 0.5, 0.8 and 1) is simply obtained by adding stoichiometric aqueous solutions of NaCl and NaBr, into an acidic aqueous solution of Bi(NO)3.5H2O in a typical ultrasonication bath at room temperature within ≈5 min. Bi/BiOClxBr1−x heterojunction films are also fabricated using a simple drop‐casting technique and tested as immobilized photocatalytic reactors. Compared to its counterparts, the Bi/BiOCl0.8Br0.2 film possesses a 3D flower‐like morphology with a highly exposed (001) facet showing the highest electron‐hole generation and separation efficiencies. In addition, the Bi/BiOCl0.8Br0.2 film demonstrates the highest photocatalytic degradation rate of the rhodamine RhB aqueous solutions (≈5 ppm), achieving ≈99% in 60 min under the visible light component of the solar spectrum. This study demonstrates the potential of LFUI as a rapid scalable synthetic strategy for cost‐effective and energy‐efficient practical production of highly active immobilized photocatalytic reactors.

Iterative Minimum Viable Product Approach to Implementing AI, RPA, and BI Solutions

Breakthrough technologies can be considered as exponentially disruptive to organizations across industries within the last few decades of the 21st century, as they have significantly altered the way their business units or customers operate. Artificial Intelligence related cognitive technologies are some of the latest disruptive solutions currently being adopted by organizations. Organizational leaders may feel both the pressure and excitement of adopting such nascent technology quickly and at scale. However, due to organizational knowledge gaps of nascent solutions, transformative large-scale initiatives have a higher risk of negative impact on failure to implement. On the other hand, an iterative approach allows for the implementation to occur in smaller amounts and leaves room for incorporating feedback and lessons learned in future iterations, thus mitigating the risks involved with the undertaking. This article breaks down the nascent field of advanced cognitive technologies into three main categories based on their business use cases: process automation, cognitive insights, and cognitive engagement. It then explores implementing this technology in each of its three categories through the lens of a popular iterative product lifecycle management approach (i.e., the Minimum Viable Product) to reduce the risk of failure or other negative impacts on an organization adopting cognitive solutions.

St. Petersburg paradox: adoption of decisions on the basis of data mining and development of software in the sphere of business analytics

This article is devoted to analysis of models of St. Petersburg paradox, as well as development of software in the sphere of business analysis. This work is based on mathematical models using theories of probability and games as well as expert survey method. It is demonstrated that the St. Petersburg paradox is a mathematical problem of probability theory with artificial conditions. The influence of this problem on economical theory is exemplified by such provisions as the principle of diminishing marginal utility, the use of expected utility as criterion of decision adoption in uncertain environment, as well as foundations of microeconomics of insurance and risk management, theory of games and some approaches to financial simulation. Adoption of decisions on the basis of the St. Petersburg paradox is analyzed. Review of main decisions of the St. Petersburg paradox and their influence for economic theory has confirmed that the St. Petersburg paradox as a mathematical problem can be used as mathematical model upon implementation of financial simulation. Comparative analysis of available BI solutions has confirmed that most of them propose all major functions, and significant differences can be revealed in penetration of expanded functions.

Single-Use Fluidic Electrochemical Paper-Based Analytical Devices Fabricated by Pen Plotting and Screen-Printing for On-Site Rapid Voltammetric Monitoring of Pb(II) and Cd(II).

This work reports the fabrication of integrated electrochemical fluidic paper-based analytical devices (ePADs) using a marker pen drawing and screen-printing. Electrodes were deposited on paper using screen-printing with conductive carbon ink. Then, the desired fluidic patterns were formed on the paper substrate by drawing with a commercial hydrophobic marker pen using an inexpensive computer-controlled x-y plotter. The working electrode was characterized by cyclic voltammetry and scanning electron microscopy. The analytical utility of the electrochemical PADs is demonstrated through electrochemical determination of Pb(II) and Cd(II) by anodic stripping voltammetry. For this purpose, the sample was mixed with a buffer solution and a Bi(III) solution, applied to the test zone of the PAD, the metals were preconcentrated as a bismuth alloy on the electrode surface and oxidized by applying an anodic potential scan. The proposed manufacturing approach enables the large-scale fabrication of fit-for-purpose disposable PADs at low cost which can be used for rapid on-site environmental monitoring.