Hasil untuk "Oils, fats, and waxes"

A. Marangoni, E. Co

Cyrill Husmann, T. Schmid, Chiara Waser et al.

Palm and palm kernel oils are preferred ingredients in industrial food processing for baked goods and chocolate-based desserts due to their unique properties, such as their distinctive melting behaviors. However, ongoing concerns about the social and environmental sustainability of palm oil production, coupled with consumer demands for palm oil-free products, have prompted the industry to seek alternatives which avoid the use of other tropical or hydrogenated fats. This project investigated replacing palm oils with chemically unhardened Swiss sunflower or rapeseed oils. Target applications were cookies and chocolate fillings. These oils were physically modified through emulsification, stabilized with finely ground oil press cake particles and crystallized waxes. Findings indicated that the emulsification of the oils increased viscosity and that the addition of wax was beneficial for long-term stability; however, the extent of this effect depended on the combination of oil and wax types. Furthermore, wax pre-crystallization and low shear during crystallization significantly improved emulsion stability. Despite these improvements, the resulting emulsions did not achieve sufficient stability and exhibited lower viscosity than palm oil. Future experiments should explore higher wax concentrations (1% or more) and develop analytical methods to better understand the wax composition and its role in oleogel formation.

ZHANG JIN, ZHANG FENGQI, ZOU YANRONG et al.

Helium is a rare inert gas with indispensable applications in defense, aerospace, and medicine. However, helium resources available for use in China are extremely limited. To date, no independently accumulated helium resources have been found. Helium is primarily found in two forms: natural gas-associated and geothermal water-dissolved. This study focused on two typical basins—the Hangjinqi area in the northern Ordos Basin and the Weihe Basin—to investigate the genesis of helium. Helium isotope mass spectrometry analysis, rock radioactive element analysis and other methods were conducted to test the assgciated gas, core samples and potential helium source rock in the surrounding areas of the study area. The results show that helium in the Hangjinqi area in the northern Ordos Basin is typically crust-derived. While in Weihe Basin, high volume fractions of mantle-derived helium (up to 6.959%) were detected near deep-seated faults penetrating the basement, such as the Baoji-Xianyang fault and the Piedmont Fault of the Qinling Mountains. Both basins are located on the southwestern margin of the North China Plate and share a basement composed mainly of Archean-Proterozoic metamorphic-granite complexes, which serve as the main source rocks of helium formation. In addition, the main source rocks for helium gas in the Weihe Basin also include the uranium-rich granites of the Yanshanian period around the periphery and the concealed granitic bodies of the same period in the deep part of the basin. Due to the low mass fractions of U and Th elements or the low helium gas content of the desorbed gas in the basement sedimentary rock complexes, they cannot be regarded as the main source rocks for helium gas. The formation, migration and accumulation of helium gas in both areas are controlled by the source rocks and faults, and are closely related to the distribution of deep-seated fault zones. These findings provide a scientific basis for the further exploration and development of helium resources in the Weihe and northern Ordos basins.

Jiaxuan HU, Changqing GUO, Zhida WANG et al.

During the process of water electrolysis,the "bubble effect" will significantly reduce the overall performance of the system.The classical nucleation theory (CNT model） fails to reveal the regulatory mechanism of the electrical double layer (EDL),surface microstructure,and mass transfer synergy on nucleation kinetics in actual electrochemical systems.This study develops an electrode interface bubble nucleation model with the synergistic effect of electrical double layer⁃mass transfer⁃surface microstructure,considering the synergistic regulation mechanism of ion migration diffusion behavior,electrode surface nano microstructure,and concentration boundary layer on the nucleation process.The research results show that the synergistic effect of EDL and microporous structurel generates significant potential gradients at the surface micropores,leading to an increase in local supersaturation and prioritizing bubble nucleation.At high overpotentials,the effect of the concentration boundary layer on nucleation energy barrier exhibits a nonlinear relationship.The thinner the concentration boundary layer is,the more significant the decreasing trend of the nucleation rate at high potential will be.The growth of bubbles is dominated by the net concentration flux near the three⁃phase contact line (TPCL),exhibiting a two⁃stage growth characteristic.The study provides a theoretical basis for optimizing the surface design of gas evolution electrodes.

Jorge Campos Pazmiño, Marc-Antoine Fortin, Véronique Fortier et al.

Purpose: To develop a technique for joint measurement of fat and water-specific longitudinal relaxation rates (R1f and R1w), effective transverse relaxation rate (R2*), and proton density fat fraction (PDFF) combining the Multi-Echo Magnetization Prepared Two Rapid Acquisition of Gradient Echoes (ME-MP2RAGE) sequence and fat-water separation. Theory and Methods: R1f and R1w were calculated with fat-specific and water-specific MP2RAGE signals. R2* and PDFF maps were obtained from fat-water separation applied to the second RAGE block. Sequence parameters optimization was performed via Cramér-Rao lower bounds theory, and we designed four protocols with different combinations of number of echoes and readout gradient schemes (I: 3 echoes unipolar, II: 6 echoes unipolar, III: 6 echoes bipolar, and IV: 10 echoes bipolar). We tested and validated these protocols with numerical simulations, phantom and in vivo experiments. In phantoms, we compared ME-MP2RAGE measurements with inversion recovery spin-echo (IR-SE) global R1 and 3D Fast Low Angle Shot (3D FLASH) R2* and PDFF. In vivo, we scanned the lower leg and neck of a healthy volunteer. Results: Numerical simulations showed accurate quantification of relaxation rates with mean relative bias < 3% and PDFF with mean bias < 0.003 using protocol ME-MP2RAGE IV (10 echoes bipolar). Phantom experiments showed excellent agreement with IR-SE and 3D FLASH measurements. In vivo, measurements in the lower leg and neck were consistent with literature values. Conclusion: We proposed an accurate method for simultaneous quantification of R1f, R1w, R2*, and PDFF from a single acquisition with the ME-MP2RAGE sequence.

Robert Graf, Hendrik Möller, Sophie Starck et al.

Volume Interpolated Breath-Hold Examination (VIBE) MRI generates images suitable for water and fat signal composition estimation. While the two-point VIBE provides water-fat-separated images, the six-point VIBE allows estimation of the effective transversal relaxation rate R2* and the proton density fat fraction (PDFF), which are imaging markers for health and disease. Ambiguity during signal reconstruction can lead to water-fat swaps. This shortcoming challenges the application of VIBE-MRI for automated PDFF analyses of large-scale clinical data and of population studies. This study develops an automated pipeline to detect and correct water-fat swaps in non-contrast-enhanced VIBE images. Our three-step pipeline begins with training a segmentation network to classify volumes as "fat-like" or "water-like," using synthetic water-fat swaps generated by merging fat and water volumes with Perlin noise. Next, a denoising diffusion image-to-image network predicts water volumes as signal priors for correction. Finally, we integrate this prior into a physics-constrained model to recover accurate water and fat signals. Our approach achieves a < 1% error rate in water-fat swap detection for a 6-point VIBE. Notably, swaps disproportionately affect individuals in the Underweight and Class 3 Obesity BMI categories. Our correction algorithm ensures accurate solution selection in chemical phase MRIs, enabling reliable PDFF estimation. This forms a solid technical foundation for automated large-scale population imaging analysis.

Tao HU, Fujie JIANG, Xiongqi PANG et al.

Taking the Lower Permian Fengcheng Formation shale in Mahu Sag of Junggar Basin, NW China, as an example, core observation, test analysis, geological analysis and numerical simulation were applied to identify the shale oil micro-migration phenomenon. The hydrocarbon micro-migration in shale oil was quantitatively evaluated and verified by a self-created hydrocarbon expulsion potential method, and the petroleum geological significance of shale oil micro-migration evaluation was determined. Results show that significant micro-migration can be recognized between the organic-rich lamina and organic-poor lamina. The organic-rich lamina has strong hydrocarbon generation ability. The heavy components of hydrocarbon preferentially retained by kerogen swelling or adsorption, while the light components of hydrocarbon were migrated and accumulated to the interbedded felsic or carbonate organic-poor laminae as free oil. About 69% of the Fengcheng Formation shale samples in Well MY1 exhibit hydrocarbon charging phenomenon, while 31% of those exhibit hydrocarbon expulsion phenomenon. The reliability of the micro-migration evaluation results was verified by combining the group components based on the geochromatography effect, two-dimension nuclear magnetic resonance analysis, and the geochemical behavior of inorganic manganese elements in the process of hydrocarbon migration. Micro-migration is a bridge connecting the hydrocarbon accumulation elements in shale formations, which reflects the whole process of shale oil generation, expulsion and accumulation, and controls the content and composition of shale oil. The identification and evaluation of shale oil micro-migration will provide new perspectives for dynamically differential enrichment mechanism of shale oil and establishing a “multi-peak model in oil generation” of shale.

Zhaoyang LIU

DENG Meizhou, NIU Na, YIN Shuang et al.

Tight sandstone gas reservoirs have the characteristics of poor physical properties of the reservoir， complex pore throat structure， strong anisotropy， and extensive coverage of initial water saturation， which lead to the complex flow mechanism of fluids in reservoirs and bring significant challenges to the accurate prediction and evaluation of gas well productivity. Therefore， based on the theory of gas-water two-phase non-Darcy flow， this study comprehensively considers the complex productivity factors， such as reservoir anisotropy， different degrees of stress sensitivity between reservoir matrix and fracture， two-phase starting pressure gradient， high-speed non-Darcy flow effect， gas slippage effect， finite conductivity of fracture， and inter-fracture interference. A new gas-water two-phase productivity prediction model for multistage fractured horizontal wells in anisotropic tight sandstone gas reservoirs is established by using coordinate transformation， perturbation ellipse theory， equivalent development rectangle theory， equivalent well diameter principle， pressure superposition principle， and hydropower similarity principle. Field examples verify the accuracy and practicability of the model. The gas-water two-phase productivity prediction curve is drawn， and the influence of sensitive parameters on productivity is evaluated. The results show that the open flow capacity of a fractured gas well increases with the increase in slippage effect， fracture conductivity， fracture half-length， fracture number， and the angles between the wellbore of the horizontal well and the main permeability of the formation. The open flow capacity of the fractured horizontal well decreases with the increase in reservoir anisotropy， reservoir stress sensitivity， fracture stress sensitivity， two-phase starting pressure gradient， and water-gas volume ratio. Water has an inhibitory effect on the flow of gas， and greater displacement pressure difference indicates a more significant inhibitory effect， so it is necessary to take waterproof and water control measures in advance. The research results further narrow the gap between the productivity prediction results of tight sandstone gas reservoirs and the actual production of the field， which is helpful for parameter evaluation， dynamic prediction， productivity evaluation， and exploration and development decision-making of tight sandstone gas reservoirs.

李玲玲1，徐妍然1，牛延菲1,2，金春秀1，胡玲华1，吴春华1 LI Lingling1, XU Yanran1, NIU Yanfei1,2, JIN Chunxiu1, HU Linghua1, WU Chunhua1

为了更好地开发与利用辣木籽，以辣木籽为原料，研究了不同体积分数乙醇（20%、40%、60%、80%）分级醇沉得到的辣木籽粗多糖（P20、P40、P60、P80）的单糖组成差异以及抗氧化活性，并采用紫外可见光谱（UV-Vis）和傅里叶红外光谱（FT-IR）对纯化后的辣木籽多糖结构进行表征。结果表明：4种辣木籽粗多糖的主要成分均为鼠李糖（Rha）、半乳糖（Gal）和葡萄糖（Glc），其中粗多糖P80中单糖总含量最高（84.09 μg/mg）；在4种辣木籽粗多糖中，P20（1 mg/mL）对DPPH自由基和超氧阴离子自由基清除率均最高，分别为50.24%、34.54%，P40（1 mg/mL）对羟自由基清除率最高，为76.92%，P80的总还原力最强；通过UV-Vis和FT-IR表征可知，不同体积分数乙醇能够对辣木籽粗多糖进行分级醇沉。综上，采用不同体积分数乙醇进行醇沉的辣木籽粗多糖有不同的抗氧化活性，需要根据具体应用有针对性地提取。In order to better develop and utilise Moringa oleifera seeds, the differences in the composition of key monosaccharides as well as antioxidant activity of crude polysaccharides (P20, P40, P60, P80) from Moringa oleifera seeds obtained by graded alcohol precipitation with different volume fraction of ethanol (20%, 40%, 60%, 80%) were investigated, and the structure of purified polysaccharides of Moringa oleifera seeds was characterized using ultraviolet-visible spectroscopy (UV-Vis) and Fourier transform-infrared spectroscopy (FT-IR). The results showed that the main components of the four crude polysaccharides were rhamnose (Rha), galactose (Gal) and glucose (Glc), among which the crude polysaccharide P80 had the highest content of total monosaccharides (84.09 μg/mg); among the four crude polysaccharides of Moringa oleifera seeds, P20 (1 mg/mL) had the highest scavenging rate of DPPH radicals and superoxide anion radicals, with 50.24% and 34.54%, respectively, P40 (1 mg/mL) had the highest scavenging rate of hydroxyl radicals（76.92%）, and P80 had the strongest total reducing power; it was known that different volume fraction of ethanol were able to carry out graded alcohol precipitation of crude polysaccharides from Moringa oleifera seeds by UV-Vis and FT-IR. In summary, crude polysaccharides extracted with different volume fraction of ethanol have different antioxidant activities and need to be extracted according to specific applications.

WANG Jie, WANG Qianjun, ZHENG Sheng et al.

Due to large burial depths， ultra-deep clastic rock reservoirs have poor physical properties and low oil and gas productivity. However， the newly drilled Well Zheng10 in Shawan Sag， Sinopec exploration area， has encountered high-quality thick reservoirs in the Triassic Karamay Formation at a buried depth of 6 700 m， and conventional tests have obtained high industrial oil and gas flow. To reveal the characteristics of this set of reservoirs and favorable main controlling factors， clarify the direction of ultra-deep clastic rock exploration， and reduce the risk of further oil and gas exploration in this area， this paper comprehensively analyzed the data of core， well logging， cast thin sections， physical properties， scanning electron microscopy， and diagenetic evolution of the reservoirs， and discussed the petrological， physical， and pore characteristics of reservoirs in the Triassic Karamay Formation in this area. The results show that the ultra-deep clastic rocks of the Triassic Karamay Formation in Well Zheng10 area are deposited in the front of the braided river delta. The lithology is dominated by glutenites， gravel-bearing fine sandstones， and fine sandstones， and the rock types are mainly feldspar lithic sandstones with low composition maturity. The remaining primary pores and solution pores dominate the reservoir space. The average porosity of the reservoirs is 9.1%， and the average permeability is 2.85 mD. The reservoir belongs to the ultra-low porosity and ultra-low permeability type and low porosity and low permeability type as a whole. Favorable sedimentary facies zones， constructive diagenesis， and abnormal high-pressure control the development and distribution of favorable reservoirs in this area. Among them， sedimentary microfacies are the basis of favorable reservoir development. The fine sandstones deposited in the underwater distributary channel at the front of the braided river delta are better sorted and rounded. The contents of the muddy matrix are low， and the physical properties of the reservoir are better， which are the dominant phase zones for favorable reservoir development. The sodium feldspar cements generated in the early diagenetic process are dissolved by acids in the later period， which increases the dissolution pores and is an essential constructive diagenesis. The abnormal high-pressures formed by continuous oil and gas charging form early and develop continuously for a long time， playing an important construction role. The research results have a guiding role for the subsequent ultra-deep oil and gas exploration in this area.

Jihye Baek, Ahmed El Kaffas, Aya Kamaya et al.

Objectives- Several ultrasound measures have shown promise for assessment of steatosis compared to traditional B-scan, however clinicians may be required to integrate information across the parameters. Here, we propose an integrated multiparametric approach, enabling simple clinical assessment of key information from combined ultrasound parameters. Methods- We have measured 13 parameters related to ultrasound and shear wave elastography. These were measured in 30 human subjects under a study of liver fat. The 13 individual measures are assessed for their predictive value using independent magnetic resonance imaging-derived proton density fat fraction (MRI-PDFF) measurements as a reference standard. In addition, a comprehensive and fine-grain analysis is made of all possible combinations of sub-sets of these parameters to determine if any subset can be efficiently combined to predict fat fraction. Results- We found that as few as four key parameters related to ultrasound propagation are sufficient to generate a linear multiparametric parameter with a correlation against MRI-PDFF values of greater than 0.93. This optimal combination was found to have a classification area under the curve (AUC) approaching 1.0 when applying a threshold for separating steatosis grade zero from higher classes. Furthermore, a strategy is developed for applying local estimates of fat content as a color overlay to produce a visual impression of the extent and distribution of fat within the liver. Conclusion- In principle, this approach can be applied to most clinical ultrasound systems to provide the clinician and patient with a rapid and inexpensive estimate of liver fat content.

D. Dimakopoulou-Papazoglou, Foteini Giannakaki, E. Katsanidis

Waxes and monoglycerides (MGs) added in edible oils form oleogels that can be used as an alternative structured fat, providing healthier substitutes to saturated and trans fats in foods. This study aimed to investigate the properties of oleogels formed by the interaction between monoglycerides and different waxes in various edible oils. For this purpose, waxes, namely rice bran (RBW), candelilla (CDW), sunflower (SW), and beeswax (BW), together with MGs in a total concentration level of 15% (w/w) were dissolved in several edible oils (olive, sunflower, sesame, and soybean). The structure and physical properties of oleogels were investigated using texture analysis, polarized light microscopy, melting point measurements, and Fourier-transform infrared spectroscopy (FTIR). The hardest structure was produced by SW/MG (5.18 N), followed by CDW (2.87 N), RBW (2.34 N), BW (2.24 N) and plain MG (1.92 N). Furthermore, RBW and SW led to a higher melting point (69.2 and 67.3 °C) than the plain MG oleogels (64.5 °C). Different crystallization structures, i.e., needle-like crystals and spherulites, were observed depending on the type of wax, its concentration, and the oil used. These results can be used to control the properties of oleogels by adjusting the gelator composition for a variety of potential food applications.

D. Thakur, Anurag Singh, Rajat Suhag et al.

Xie Jianyong, Cheng Hui, Chu Yanjie et al.

The failure diagnosis indicators are featured by nonlinear separable similarity and uncertain relationship between failures and indications.It is difficult to conduct effective failure diagnosis on site for the electric submersible screw pump(EPCP)unit.Based on the statistical process control extended criterion and empirical judgment,multi-parameter rule charts,failure weight factor and normalization of collected field data,a failure diagnosis model of ESPCP unit was established,and a failure diagnosis method of multi-parameter process control was proposed.The operation and failure types of electric submersible screw pump unit are divided into 12 working conditions,7 characteristic parameters such as electrical parameters and production parameters were selected to characterize the production conditions of oil wells,and the judgment criteria and weight factors of on-site failure conditions were determined.Combined with the judgment trend of process control extended criteria and data feedback analysis,the failure with the highest probability is output.According to the on-site measured parameters of more than 20 failure wells in Xinjiang Oilfield,example calculation and verification analysis were carried out.The results show that the failure diagnosis method of multi-parameter process control and data feedback has strong analysis function and visualization.It provides theoretical basis and technical support for timely diagnosis and accurate judgment of the operation conditions and failures of ESPCP units.

Huang Liang, Guo Ruifeng, Wu Chunhong et al.

In view of the excessive damage of the conventional slip-type bridge plug to casing during anchoring,an inserted-tooth slip-type bridge plug was proposed and designed.The burst strength,circumferential strain and circumferential elongation of casing were calculated using the thick-wall cylinder model of the elastic theory and the finite element method,and the contact pressure and penetration depth between the slip tooth and the inner casing wall after the bridge plug anchoring were analyzed.The analysis shows that the higher side of the upper slip tooth is associated with higher stresses reaching the strength of cemented carbide,while those of the rest parts of the bridge plug are relatively low.After setting,the first row of teeth of the lower slip generates great stresses,and the teeth of the lower slip evenly contact the inner casing wall along the casing circumference,which provides solid installation and tight seal.Moreover,the inserted tooth has minor effects on the surface stress of casing.Finally,the casing anchoring testing was performed for the inserted-tooth slip,which shows that the pressure-bearing capacity and setting performance of the slip after setting are relatively stable and verified the structure design of the carbide slip.The findings of this research provide theoretical and experimental data for design optimization and application promotion of inserted-tooth slip-type bridge plugs in coiled tubing drilling of horizontal wells.

Yunjin WANG, Fujian ZHOU, Hang SU et al.

Considering the characteristics of carbonate reservoirs in the Middle East, a low-viscosity microemulsion acid that can be prepared on site and has an appropriate retardation ability was developed. It was compared with four conventional acid systems (hydrochloric acid, gelled acid, emulsified acid and surfactant acid) through experiments of rotating disk, multistage acid fracturing and core flooding with CT scanning. The micro-etching characteristics and conductivity of fracture surfaces were clarified, and the variation of saturation field during water invasion and flowback of spent acid and the recovery of oil phase relative permeability were quantitatively evaluated. The study shows that the addition of negatively charged agent to the oil core of microemulsion acid can enhance its adsorption capacity on the limestone surface and significantly reduce the H+ mass transfer rate. Moreover, the negatively charged oil core is immiscible with the Ca2 + salt, so that the microemulsion acid can keep an overall structure not be damaged by Ca2 + salt generated during reaction, with adjustable adsorption capacity and stable microemulsion structure. With high vertical permeability along the fracture walls, the microemulsion acid can penetrate into deep fracture wall to form network etching, which helps greatly improve the permeability of reservoirs around the fractures and keep a high conductivity under a high closure pressure. The spent microemulsion acid is miscible with crude oil to form microemulsion. The microemulsion, oil and water are in a nearly miscible state, with basically no water block and low flowback resistance, the flowback of spent acid and the relative permeability of oil are recovered to a high degree.

Azeez Adebisi, Ajiboye Abd-Rasheed, Tomomewo Olusegun et al.

Owing to strict emission-policies, vehicle manufacturers are mandated to control hazardous emissions from diesel engines. One novel step adopted in this work, is the use of hydrogen enrichment with nanofuel, where TiO2 nanoparticles- Afzelia Africana biodiesel-mix was blended with hydrogen for use in a diesel engine. 25 ppm TiO2 nanoparticles were admixed with biodiesel and ultrasonicated. Thereafter, H2 was introduced through the air inlet at the lowest possible flow rate (3–4 LPM) to avoid reaching H2/air explosion limit. The ratio of H2 to the blended fuels (BNH) is (15: 85 vol/vol %). The effects of the nanofuels blended with pure H2 were investigated by evaluating the brake thermal efficiency (BTE), wall temperature of the combustion chamber, NOx, CO, and HC emissions. Via a simplified model, the associated uncertainties in the parametric variations were determined while a Supervisory Computer Aided Data Acquisition (SCADA) system with an in-built program, was configured in the engine set-up for data generation. The results showed that higher BTE of the blends + 25 ppm TiO2 alongside hydrogen flowrates of 3 LPM and 4 LPM helped to improve the engine performance with lesser emissions of CO, NOx and HC respectively. Sample BNH@-3-LPM gave the best performance/BTE of 39.5 % compared to BNH@-4-LPM (32.4 %), BN (29 %) and diesel (29.4 %), whereas, BNH@-3-LPM gave the lowest emissions of 0.4, 5 and 81 g/kwh for CO, HC and NOx respectively compared with diesel which gave corresponding emissions of 0.8, 35 and 200 g/kwh for CO, HC and NOx respectively.

Carolina van Baalen, Jacopo Vialetto, Lucio Isa

Monolayers of colloidal particles at oil-water interfaces readily crystalize owing to electrostatic repulsion, which is often mediated through the oil. However, little attempts exist to control it using oil-soluble electrolytes. We probe the interactions amongst charged hydrophobic micospheres confined at a water/hexadecane interface and show that repulsion can be continuously tuned over orders of magnitude upon introducing minor amounts of an organic salt into the oil. Our results show that charged groups at the particle/oil interface are subject to an associative discharging mechanism, analogous to the charge regulation kinetics observed for charged colloids in non-polar solvents.

Attila Jung, Dömötör Pálvölgyi

We prove a fractional Helly theorem for $k$-flats intersecting fat convex sets. A family $\mathcal{F}$ of sets is said to be $ρ$-fat if every set in the family contains a ball and is contained in a ball such that the ratio of the radii of these balls is bounded by $ρ$. We prove that for every dimension $d$ and positive reals $ρ$ and $α$ there exists a positive $β=β(d,ρ, α)$ such that if $\mathcal{F}$ is a finite family of $ρ$-fat convex sets in $\mathbb{R}^d$ and an $α$-fraction of the $(k+2)$-size subfamilies from $\mathcal{F}$ can be hit by a $k$-flat, then there is a $k$-flat that intersects at least a $β$-fraction of the sets of $\mathcal{F}$. We prove spherical and colorful variants of the above results and prove a $(p,k+2)$-theorem for $k$-flats intersecting balls.