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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]

To detect optimum well locations for new injection wells one must generally notice to existing well locations, reservoir shape, capital cost per well construction in each area as well as recovery increase relevant to new well layout. Designing injection process presents inverse optimization issue whereas adjusting exploitation wells prior to primary recovery exhibits classic optimization problem. Most important design factor namely injection well layout has no unique explicit solution to solve via analytical or numerical techniques thus one can propose meta or hyper heuristic approaches to solve such problems. Our main novelty in this work is that here we cooperate four heuristic optimization approaches with our self made fast simulation technique to optimize well locations for two exemplar miscible gas injection processes. We employ MATLAB software to construct artificial porous media prototypes with different uncertainties to investigate optimization technique performances in low rather than high risk media. Outcomes illustrate that approaches like artificial immune system or particle swarm optimization which exhibit strong local search can effectively detect optimal well locations in high risk porous media. Results also show that solution techniques such as Monte Carlo that have strong global search capabilities at expense of weak local search can discover optimum well locations only in media with low uncertainty. • By using heuristic techniques for optimizing injection rather than production well layout in reservoirs that exhibits high uncertainty one can improve oil extraction efficiency to more than 10%–15%. • Heuristic techniques such as particle swarm or artificial immune system that have higher local search capabilities can more strongly improve well locations in high risk media with zonal or laminate heterogeneity. • Optimization approaches that express weak local search abilities like Monte Carlo fail to detect optimal layout for injection wells in extremely disparate porous media specially at inadequate number of iterations. • Fast simulation approach is several times faster than full multiphase flow simulation when mining in large volume data whereas convergence times are almost same when working with small volume data. [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]

PurposeTo evaluate the efficacy and safety of Artisan–Verysise intraocular lens (IOL) secondarily implanted for aphakic correction in post-traumatic vitrectomized eyes.MethodsPostoperative outcomes of secondary implantation of an iris-supported Artisan IOL in 17 unilateral aphakic patients with previous pars plana vitrectomy secondary to posterior segment trauma were evaluated prospectively. Eyes had vitrectomized in previous 6–60 months. After complete ophthalmologic examination, IOL implantation was performed through a scleral tunnel incision. Patients were followed for visual outcome, endothelial cell density (ECD) and occurrence of complications. Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), spherical equivalents (SE), and ECD were compared before and after IOL insertion.ResultsPatients' postoperative mean follow-up were 14.65±5.21 months. UCVA improved in all patients. (0.03±0.1 preoperatively vs 0.45±0.29 postoperatively, P=0.0001). However improvement of BCVA was not significant. Mean postoperative SE was 0.84±1.32 D, whereas it was 10.85±1.70 D preoperatively (P=0.0001). SE was within ±2.00 D of emmetropia in 16 eyes (94.1%). Mean endothelial cell loss was 8.1% in first 6 postoperative months.All eyes achieved the desired anatomic results. No intraoperative complications occurred in any of our cases. Complications were transient pigmented precipitates (three cases), choroidal detachment (one case), and transient vitreous haemorrhage (one case).ConclusionSecondary Artisan IOL implantation is an effective and safe procedure to correct aphakia in vitrectomized eyes without capsular support after trauma. Considering good visual rehabilitation and low rate of complications, this procedure is recommended in vitrectomized eyes.Eye (2008) 22, 1419–1424; doi:10.1038/eye.2008.271; published online 29 August 2008 [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]

Macaque monkeys infected with various neurovirulent forms of simian immunodeficiency virus (SIV) represent highly effective models, not only of systemic acquired immunodeficiency virus (AIDS), but also neuroAIDS. Behavioral studies with this model have clearly established that SIV-infected monkeys show both cognitive and motor impairments resembling those that have been reported in human immunodeficiency virus (HIV)-infected humans. This paper combines data from a number of behavioral studies in SIV-infected macaque monkeys to obtain an overall estimate of the frequency of impairments in various motor and cognitive domains. The results were then compared to similar data from studies of HIV-infected humans. Whereas cognitive functions are most commonly impaired in HIV-infected humans, motor function is the domain most commonly impaired in SIV-infected monkeys. Electrophysiological studies in SIV-infected macaques have revealed deficits in motor-, somatosensory-, visual-, and auditory-evoked potentials that also resemble abnormalities in human HIV infection. Abnormalities in motor-evoked potentials were among the most common evoked potential deficits observed. Although differences in behavioral profiles of human HIV disease and SIV disease in monkeys exist, the results, nevertheless, provide strong validation for the use of macaque models for translational studies of the virology, immunology, pathophysiology, and treatment of neuroAIDS. [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]

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]

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 precipitation and deposition of asphaltene are among the least understood phenomena in upstream to downstream oil-related processes. The present experimental study investigated the impact of different connate water types on precipitation and deposition of asphaltene from synthetic oil solutions comprising of toluene, n-heptane with 5 wt% of asphaltene in a uniformly patterned glass micromodel. To do so, different types of connate water including deionized water (DW) and brines such as CaCl 2 , MgCl 2 , KCl, NaCl, and Na 2 SO 4 ranging from 5000 to 40,000 ppm were investigated. It was found that the type of cations present in the brine would profoundly influence the precipitation of asphaltene, probably due to their higher affinity toward anionic components. Divalent cations were also found to cause much more severe asphaltene precipitation compared to monovalent cations. Connate water saturation of different brines was also found to have diverse impact on precipitation and deposition of asphaltene given the type of cations present in the aqueous phase. Moreover, brine concentration influenced the amount of precipitated asphaltene due to the salting-in and salting-out effects. [ABSTRACT FROM AUTHOR]

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]

Asphaltene extracted from a crude oil covers a wide range of molecules that would similarly act in terms of solubility in general but they may differ in terms of precipitation behavior due to different molecular structures. For this reason, they are commonly represented as a solubility class, not a particular molecule though each sub-fraction of asphaltene may have its own precipitation tendency. In recent years, the impact of water presence on the precipitation of these molecules has attracted attention due to increased production of water, although the reported results are somewhat inconsistent. In this study, a systematic experimental study was performed to investigate the impact of aqueous phase, which composed of deionized water and ions of single, double, and three valence with net positive and negative charges on asphaltene precipitation from a synthetic oil composed of toluene and asphaltene. The aqueous phase was emulsified within this synthetic oil phase using ultrasonic mixer. Then, the oil phase was divided into three fractions named oil 1, 2, and 3, respectively depending on the degree of their desire to remain in the emulsion. The results showed that oils 1, 2, and 3 have different precipitation curves. The precipitation became more intensified even up to four fold from oil 1 to 3. Moreover, the presence of ions with higher valence in the aqueous phase drew extra asphaltene molecules from oil 1 to oil 2 and then oil 3 (i.e. from bulk to the interface) which, in turn, changed the precipitation curve. The experimental results also showed that the relative concentration of asphaltene sub-fractions in oils 1, 2 and 3 determines the shape of the final precipitation curve and the onset point of precipitation. Unlabelled Image • A new simple and robust approach to identify sub-fractions of asphaltene. • Impact of brines of different ions on precipitation of asphaltene. • Different classes of asphaltene were distributed in the presence of different brines. • Each class showed different propensity of asphaltene to precipitate. • Ions of higher valence increased asphaltene presence at the interface of oil and water. [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]

As crude oil gets denser and heavier, the precipitation and deposition of asphaltene causes severe problems in various sectors of oil industry from oil reservoirs to refineries. Asphaltene deposition in some wellbores may cause a partial or total production loss depending on its severity. Several studies have attempted to model asphaltene deposition along the wellbore in which a fixed shape of deposited asphaltene profile is assumed over time. Having said though there exist field experiences which report evolutionary behavior of deposited asphaltene in terms of growth pattern and structure. In this study, a new model is proposed that considers the removal propensity of deposited asphaltene from the wall along with its deposition in another location of the same well. The structure of asphaltene deposits, their growth pattern and movement during production which is predicted in this model are consistent with the field data quantitatively. The proposed model also predicts that as production continues, the deposits in some locations of the well get thicker and the consequent increase in pressure drop lowers the location of bubble point which causes dissolution and removal of asphaltene in upper parts due to higher solubility of asphaltene and higher velocity of fluid in that region. Thus, the proposed model would more accurately simulate the wellbore deposition as compared with a field case-study. The finding of this study is hence a step forward for understanding of the behavior of asphaltene deposition in oil producing wells. • Prediction of asphaltene blockage in vertical wellbores during oil production • Model includes evolutionary behaviour of deposition, removal and dissolution. • Location of asphaltene blockage would be shifted given local pressure and velocity. • Consistency of the theoretical results with the field data. [ABSTRACT FROM AUTHOR]