Search

The precipitation of asphaltene and waxes occurs when crude oil characteristics change as a consequence of pressure, temperature variations, and/or chemical modifications, etc. The costs associated with the cleaning of deposition on the production equipment and the loss of profit opportunities can go beyond hundreds of millions of USD. Thus, there is a strong incentive to search for ways to mitigate deposit formation during the crude production process. A light crude bottom hole fluid sample from a deep well with an asphaltene deposition problem was analyzed in the laboratory. Basic data on density, viscosity, bubble point, GOR, and asphaltene onset pressure were measured at a PVT laboratory. Asphaltene characterization, as a prescreening for appropriate inhibitors, has been conducted using asphaltene phase diagrams (APD). The APD generated from two developed software programs in both Matlab and Excel codes were favorably compared with the phase behavior of other oil samples available in the literature and has shown to be an excellent match. Various test methods were used to demonstrate the asphaltene instability of the oil samples. Eleven chemical inhibitors from five global companies were screened for testing to inhibit the precipitation. The optimum concentration and the amount of reduction in precipitation were determined for all of these chemicals to identify the most suitable chemicals. Finally, some recommendations are given for the field application of chemicals. [ABSTRACT FROM AUTHOR]

Designing custom secure function evaluation compilers has been an active research area. However, intelligent adaptation of the integrated circuit synthesis tools outperforms these compilers. It is time for the custom compilers to embrace this trend. [ABSTRACT FROM AUTHOR]

Emerging complex deep neural networks require vast amounts of data to achieve high precision. However, the information is often collected from user logs and personal data. In this article, we summarize recent cryptographic methodologies for provably privacy-preserving deep learning and inference. [ABSTRACT FROM AUTHOR]

We introduce CAMsure, the first realization of secure Content Addressable Memory (CAM) in the context of approximate search using near-neighbor algorithms. CAMsure provides a lightweight solution for practical secure (approximate) search with a minimal drop in the accuracy of the search results. CAM has traditionally been used as a hardware search engine that explores the entire memory in a single clock cycle. However, there has been little attention to the security of the data stored in CAM. Our approach stores distance-preserving hash embeddings within CAM to ensure data privacy. The hashing method provides data confidentiality while preserving similarity in the sense that a high resemblance in the data domain is translated to a small Hamming distance in the hash domain. Consequently, the objective of near-neighbor search is converted to approximate lookup table search which is compatible with the realizations of emerging content addressable memories. Our methodology delivers on average two orders of magnitude faster response time compared to RAM-based solutions that preserve the privacy of data owners. [ABSTRACT FROM AUTHOR]

Injection of CO 2 , as a redundant gas, is considered as one of the most viable options to enhance oil recovery. The performance of this process may though be compromised in the event of severe precipitation and deposition of asphaltene. In this study, the effect of Co 3 O 4 nanoparticles with various concentrations of 0.01, 0.1 and 1.0 wt% on precipitation of asphaltene during CO 2 injection was investigated by means of interfacial tension (IFT) measurements. The addition of Co 3 O 4 nanoparticles to synthetic solutions comprising of n-heptane, toluene and 5 wt% asphaltene and crude oil caused the IFT to decrease linearly as a function of pressure with two different slopes. In the first region, CO 2 dissolved in the oil phase while in the second region, asphaltene was prone to precipitation. The IFT reduced at lower slope in the second region. It was found that the addition of nanoparticles to the synthetic and crude oils resulted in more asphaltene particles adsorption on the surface of nanoparticles. In addition, more stable dispersion of asphaltene nano-aggregates could be attained. Consequently, the ultimate recovery of asphaltenic oil would take place in reservoir conditions during CO 2 injection due to less aggregation and precipitation of asphaltene particles. Finally, the optimum concentration of dispersed Co 3 O 4 nanoparticles was found to be 0.1 wt%. [ABSTRACT FROM AUTHOR]

Background & objectives: Leptospirosis is a widespread zoonotic disease and a public health problem, particularly in tropical and subtropical countries. Varied clinical manifestations of the disease frequently lead to misdiagnosis resulting in life-threatening multi-organ complications. Therefore, early laboratory investigation using an appropriate diagnostic approach is crucial. In the present study, a potential protein marker was identified and evaluated for its usefulness in the serodiagnosis of acute leptospirosis. Methods: Leptospira interrogans serovar Icterohaemorrhagiae (L44), which represents a commonly prevalent serovar in Malaysia, was cultivated for preparation of sequential protein extract (SEQ). SDS-PAGE and immunoblotting were performed with a serum panel comprising confirmed cases of leptospirosis and controls (n=42 each). Identification and characterization of the highest scoring protein from the antigenic band was performed. Subsequently based on the nucleotide coding sequence of the protein, the corresponding recombinant protein was custom-produced. It was then evaluated for sensitivity and specificity by testing against 20 serum samples from leptospirosis patients and 32 from controls. Results: Among the antigenic components, a 72kDa protein band demonstrated significant sensitivity (83.3%) and specificity (95.2%) for the detection of specific anti-leptospiral IgM antibodies. The protein was identified by mass-spectrometry analysis as heat shock protein DnaK of L. interrogans. Recombinant form of the protein (r72SEQ) showed 85 per cent sensitivity and 81 per cent specificity for the detection of specific anti-leptospiral IgM antibodies. Interpretation & conclusions: The findings of our study indicate that a protein (72kDa) of L. interrogans has the potential utility of being used for the diagnosis of acute leptospirosis. Further studies need to be done to confirm these findings. [ABSTRACT FROM AUTHOR]

Enzyme-linked immunosorbent assays (ELISAs) were developed for the detection of Ig G, Ig G4 and Ig E antibodies against Strongyloides stercoralis. A commercial ELISA ( IVD Research, USA) was also used, and the sensitivities and specificities of the four assays were determined. Serum samples from 26 patients with S. stercoralis infection and 55 patients with other infections or no infection were analysed. Sensitivities of the Ig G4, Ig G, Ig E and Ig G ( IVD) assays were 76·9%, 84·6%, 7·7% and 84·6%, respectively, while the specificities were 92·7%, 81·8%, 100% and 83·6%, respectively. If filariasis samples were excluded, the specificities of the Ig G4- ELISA and both Ig G- ELISAs increased to 100% and 98%, respectively. A significant positive correlation was observed between Ig G- and Ig G4- ELISAs ( r = 0·4828; P = 0·0125). Ig G- and Ig G- ( IVD) ELISAs ( r = 0·309) were positively correlated, but was not significant ( P = 0·124). Meanwhile there was no correlation between Ig G4- and Ig G- ( IVD) ELISAs ( r = 0·0042; P = 0·8294). Sera from brugian filariasis patients showed weak, positive correlation between the titres of antifilarial IgG4 and the optical densities of anti- Strongyloides Ig G4- ELISA ( r = 0·4544, P = 0·0294). In conclusion, the detection of both anti- Strongyloides Ig G4 and Ig G antibodies could improve the serodiagnosis of human strongyloidiasis. Furthermore, patients from lymphatic filariasis endemic areas who are serologically diagnosed with strongyloidiasis should also be tested for filariasis. [ABSTRACT FROM AUTHOR]

In this article, difficulties in accurate estimation of thermophysical properties of heavy petroleum fluids and natural gas systems through conventional methods are discussed. Potential approaches in characterization of such systems that use direct measurable properties of mixtures are investigated. It is shown that properties such as velocities of sound and light and dipole moment might be appropriate properties to measure for characterization and property estimation of heavy petroleum fluids. [ABSTRACT FROM AUTHOR]

In this paper a semianalytical model has been proposed to predict the rate at which oil components dissolve in water when an oil spill occurs in a marine environment. The model breaks the oil into a number of pseudocomponents proportional to the number of compounds originally present in the oil and calculates the rate of dissolution for each component. In addition, the components are divided into paraffinic, naphthenic, and aromatic hydrocarbon types and the amount of dissolution of each pseudocomponent is calculated versus time. In this method the concentration of most toxic components of oil (mainly monoaromatics) is determined. The model considers variable surface area and slick thickness and requires oil specifications (i.e., American Petroleum Institute [API] gravity and boiling point) in addition to air and water temperatures and speeds. The model has been applied to a Kuwaiti crude oil and its products naphtha and kerosene samples at 20°C and 40°C. The results could be useful in selection of an appropriate method for oil spill clean up as well as simulation of environmental impact of oil spill from toxicity points of view. [ABSTRACT FROM AUTHOR]

The cochlear microphonic (CM) may play an important role in the diagnosis of auditory neuropathy (AN) in newborns. However, since the CM tends to mirror the waveform of the acoustic stimulus, conscientious recording methodology must be applied to separate true response from artifact. The difficulty in achieving this separation has limited the clinical usefulness of the CM. In an effort to call attention to the importance of recording protocol when measuring the CM, the present study was designed to optimize CM recordings in humans by investigating the following parameters: (1) secondary minus electrode recording site (mastoid versus ear canal [EC]), (2) stimulus parameters, and (3) grounding and shielding conditions. Normative data were collected in full-term newborns (n = 7) and adults (n = 4) with no known risk factors for cochlear or retrocochlear pathology. Results suggest that the CM is easier to separate from stimulus artifact using an EC electrode and toneburst stimuli. In addition, electromagnetic shielding and grounding of the electrode cables and the acoustic transducer were effective in reducing and/or eliminating stimulus artifact. Results from this normative study may be helpful in improving the diagnostic utility of the CM in AN and other hearing-related disorders. [ABSTRACT FROM AUTHOR]

A new correlation is developed for predicting the Reid vapor pressure (RVP) of gasoline and naphtha based on a true vapor pressure (TVP) correlation. The input parameters for this correlation are the mid-boiling point, specific gravity, critical temperature, and critical pressure, where the critical properties may be estimated from the boiling point and specific gravity using available methods. The proposed correlation is evaluated with data collected on 50 gasoline samples from crude oils from around the world with API gravity ranges from 41 to 87, average boiling point ranges from 316 to 494 K and RVP of 0.007 to 1.15 bars (0.1–17 psia). The average error from the proposed correlation is about 0.06 bar (0.88 psia). Two other simple methods for prediction of RVP available in the literature have been evaluated with the same data bank and compared with the proposed method. [ABSTRACT FROM AUTHOR]

The heart is an important target organ for cholinergic function. In this study, muscarinic receptor subtype(s) in the human heart were determined using reverse transcription-polymerase chain reaction. Our results demonstrated muscarinic receptor M2 and M3 subtype RNA in left/right atria/ventricles of donor hearts. Receptor autoradiography analysis using selective muscarinic ligands indicated an absence of M1 receptor subtype in the human heart. The level of muscarinic receptor binding in atria was two to three times greater than in ventricles. Our results suggest that muscarinic receptors in the human heart are of the M2 and M3 subtypes. This is the first report of M3 receptors in the human myocardium. [ABSTRACT FROM AUTHOR]

Mechanical behavior of rocks would have substantial implications for different operations from fluid injection and hydraulic fracturing in hydrocarbon reservoirs to underground carbon dioxide storage in the crust of the earth. In all of these operations, restricting the undesired seismicity events and preserving the integrity of formations is a crucial subject that enforces engineers to evaluate the mechanical behaviors of constituent rocks and predict the formation response. Tensile strength is an important factor for maintaining caprock and reservoir formation from induced tensile cracking which can be influenced by the pore fluid. This paper focuses on the tensile strength of carbonate rock, as an important reservoir rock, in the presence of seawater, as a common injection fluid candidate for enhanced oil recovery objectives. For this purpose, twelve dolomite samples from the Asmari-Jahrum Formation outcrop in Fars province, Iran, were prepared for performing tensile tests. Also for a thorough comparison, sample properties, fluid contents, digital image correlation measurements, and a finite element simulation have been investigated. The experimental results showed a noticeable reduction in the tensile strength of dolomite samples in the presence of distilled water and seawater. In comparison with a dry sample though, a reduction of 16% tensile strength for a seawater saturated sample was observed for similar samples. Among the various mechanisms, which are reported in the open literature, the hydration force seems to be the main reason for the tensile strength reduction and this conclusion was examined by measuring the mass of vaporized adsorbed water on the powder of the same dolomite sample. In addition by testing flooded samples, the impact of flow on the tensile strength was examined. For both cases of seawater and distilled water flooding, the samples which were placed in the outlet zone during the flooding showed lower tensile strength. Moreover, simulation results confirmed the similarity of the weakening trend and impact of seawater. • Impact of pore fluid on the tensile strength of dolomite rocks. • Combining the Brazilian test with the digital image correlation technique. • Hydration force impact on the mass of vaporized adsorbed water. • Simulation of the indirect tensile test using the extended finite element. • Effluent components of dolomite flooded samples. [ABSTRACT FROM AUTHOR]

The amount of precipitated asphaltene can be considerably reduced with pretreatment of asphaltene inhibitor, in the crude oil. Efficiency of asphaltene inhibitors mainly depends on some parameters such as pH of the oil and the chemical structure of asphaltene inhibitors. In this paper, the amounts of asphaltene precipitation have been experimentally measured using two n-paraffin precipitants; n-heptane and n-hexane. The performance of the studies on the asphaltene accumulation was studied using Fourier-Transform Infrared (FTIR) Spectroscopy analysis. The onset point has been determined by three different commercial asphaltene inhibitors. The results show that when an asphaltene inhibitor is not injected into the mixture of synthetic oil/n-heptane, AOP (Asphaltene Onset Point) occurs at 35 vol.% of n-heptane, while with addition of 3000 ppm of asphaltene B inhibitor, AOP occurs at 60 vol.% of n-heptane.

In-situ emulsification of injected brines of various types is gaining increased attention for the purpose of enhanced oil recovery. The present experimental study aims at evaluating the impact of injecting various solutions of Na2CO3 and MgSO4 at different flow rates resembling those in the reservoir and near wellbore using a glass micromodel with different permeability regions. Emulsification process was visualized through the injection of deionized water and different brines at different flow rates. The experimental results showed that the extent of emulsions produced in the vicinity of the micromodel exit was profoundly higher than those at the entrance of the micromodel. The injection of Na2CO3 brine after deionized water caused the impact of emulsification process more efficiently for attaining higher oil recovery than that for the MgSO4 brine. For instance, the injection of MgSO4 solution after water flooding increased oil recovery only up to 1%, while the equivalent figure for Na2CO3 was 28%. It was also found that lower flow rate of injection would cause the displacement front to be broadened since the injected fluid had more time to interact with the oil phase. Finally, lower injection flow rate reduced the viscous force of the displacing fluid which led to lesser occurrence of viscous fingering phenomenon.

Asphaltene deposition may cause profound formation damages in oil reservoirs. Solvents of various types can be used to remove asphaltene deposition though they are expensive and prone to safety hazards and detrimental environmental consequences. In this study, emulsified solvents (i.e. toluene/water emulsions) were investigated as an alternative approach for the removal of asphaltene deposition in porous media. Three different emulsions (90/10, 80/20, 70/30 vol percentages of water in oil emulsions) were prepared and injected at two injection rates of 0.1 and 1.0 cc/hr into a transparent heterogeneous micromodel containing deposited asphaltene to evaluate their ability to either dislodge or dissolve asphaltene deposition and also to compare their performance with the use of pure toluene in both microscopic and macroscopic scales. The results showed that all of the investigated emulsions were able to remove, to some extent, the deposited asphaltene despite having a lower volume fraction of toluene. Furthermore, emulsions swept the whole area of porous media, but toluene left more than half the area of micromodel un-swept. Emulsion 70/30 (w/o) was found to be the optimum solvent as it removed all of the deposited asphaltenes at lower injected pore volumes. It was also found that the deposited asphaltene was removed with injecting lower pore volume of solvents, which was due to higher toluene penetration into deposition as the emulsified solvent flowed slower in the micromodel. • Emulsified solvents remove asphaltene deposition better than conventional solvents. • Emulsion 70-30 water/oil was better than others due to lower use of toluene. • Displacement efficiency of emulsions are higher because of favorable mobility ratio. • More efficient sweep efficiency when emulsified solvents were injected at lower rates. [ABSTRACT FROM AUTHOR]

The in-depth knowledge of reservoir heterogeneity is imperative for identifying the location of production and injection wells. The present study aimed at experimentally investigating the process of water flooding in the viscous oil-saturated glass micromodels, which contain layers with different permeability where the fractures were placed in different locations. Computational Fluid Dynamics (CFD) simulations of flooding were also conducted to study the impact of different water flow rates and wettability states. The results showed that the fractures, which have a deviation with the trend of maximum pressure gradient line, would widen the water path and vice versa. The performance of injection wells would increase the recovery factor by 18% if these would be located in the zones with high permeability for low flow rates of water. With changes in wettability state from water to oil wet conditions, the oil production will increase by 11%. Computational Fluid Dynamics results also indicated that an increase in the capillary number from 0.8 × 10−6 to 1.6 × 10−5, would cause the recovery factor to decrease as much as 14.34% while further increase from 1.6 × 10−5 to 2.24 × 10−5, the oil production will increase by 9.5%. Comparison between the obtained oil recoveries indicates that the maximum oil recoveries will happen when the injector well is located in the zone where ascending permeability, capillary number greater than 4.81 × 10−6 and also fracture with the most deviation with pressure gradient line (i.e. angular pattern) are gathered in an area between the injection and production wells.

Balance theory proposed by Heider for the first time modeled triplet interaction in a signed network, stating that relationships between two people, friendship or enmity, is dependent on a third person. The Hamiltonian of this model has an implicit assumption that all triads are independent, meaning that the type of each triad, being balanced or imbalanced, determined apart from the state of other triads. This independence forces the network to have completely balanced final states. However, there exists evidence indicating that real networks are partially balanced, raising the question of what is the mechanism preventing the system to be perfectly balanced. Our suggestion is to consider a quartic interaction which dissolves the triad's independence. We use the mean-field method to study the thermal behavior of such systems where the temperature is a parameter that allows the stochastic behavior of agents. We show that under a certain temperature, the symmetry between balanced and imbalanced triads will spontaneously break and we have a discrete phase transition. As a consequence, stability arises where either similar balanced or imbalanced triads dominate, hence the system obtains two new imbalanced stable states. In this model, the critical temperature depends on the second power of the number of nodes, which was a linear dependence in thermal balance theory. Our simulations are in good agreement with the results obtained by the mean-field method. [ABSTRACT FROM AUTHOR]

Abstract In recent years, smart waterflooding has gained increased attention as an emerging EOR technology both for carbonate and sandstone reservoirs which would offset the need for utilization of toxic or expensive chemicals. Wettability alteration is one of the main mechanisms in smart waterflooding to improve oil recovery. Most previous studies showed that the rock wettability alteration toward water wetting conditions would help to recover oil. In this study, wettability alteration is investigated for a dolomite rock using the sessile drop method. The effects of monovalent and divalent cationic (K+ and Mg2+) and anionic (Cl− and SO 4 2−) brines are discerned for different combination of various salts and concentrations of less than 5000 ppm. The experimental results showed that wettability would profoundly be changed for low salinity water in the presence of MgSO 4 and KCl. The resultant findings are based on wettability alteration index (WAI) for different solutions and concentrations. It was found that KCl and MgSO 4 can alter wettability up to 90% from strongly oil-wet to profoundly water-wet state within the range of investigated salt concentrations in this study. It was also found that double layer expansion and action of SO 4 2− as a catalyst were the prevailing mechanisms in the process of wettability alteration. Highlights • Wettability of dolomite surface during smart water injection is investigated. • Impact of NaCl, KCl, MgSO 4 and MgCl 2 as per salinity is examined. • Order of wettability alteration is: KCl ≥ MgSO 4 > MgCl 2 > NaCl > formation brine. • Monovalent cation bonded to the chloride anion showed better performance. • NaCl and KCl as a function of concentration showed different wettability behavior. [ABSTRACT FROM AUTHOR]

Water-soluble graphene quantum dots (GQDs) have recently exhibited considerable potential for diverse biomedical applications owing to their exceptional optical and chemical properties. However, the pronounced heterogeneity in the composition, size, and morphology of GQDs poses challenges for a comprehensive understanding of the intricate correlation between their structural attributes and functional properties. This variability also introduces complexities in scaling the production processes and addressing safety considerations. Light and sound have firmly established their role in clinical applications as pivotal energy sources for minimally invasive therapeutic interventions. Given the limited penetration depth of light, photodynamic therapy (PDT) predominantly targets superficial conditions such as dermatological disorders, head and neck malignancies, ocular ailments, and early-stage esophageal cancer. Conversely, ultrasound-based sonodynamic therapy (SDT) capitalizes on its superior ability to propagate and focus ultrasound within biological tissues, enabling a diverse range of therapeutic applications, including the management of gliomas, breast cancer, hematological tumors, and modulation of the blood-brain barrier (BBB). Considering the advancements in theranostic and precision therapies, reevaluating these conventional energy sources and their associated sensitizers is imperative. This review introduces three prevalent treatment modalities that harness light and sound stimuli: PDT, SDT, and a synergistic approach that integrates PDT and SDT. This study delineated the therapeutic dynamics and contemporary designs of sensitizers tailored to these modalities. By exploring the historical context of the field and elucidating the latest design strategies, this review underscores the pivotal role of GQDs in propelling the evolution of PDT and SDT. This aspires to stimulate researchers to develop "multimodal" therapies integrating both light and sound stimuli.