Nuclear Magnetic Resonance Scans Research Articles

Perlite incorporation for sedimentation reduction and improved properties of high-density geopolymer cement for oil well cementing

Portland cement (PC) is known for its environmental and technical concerns and massive energy consumption during manufacturing. Geopolymer cement is a promising technology to totally replace the use of PC in the oil and gas industry. Although geopolymers are widely used in the construction industry, it is yet to see a full-scale application in the petroleum industry. High-density geopolymer cement development is essential to substitute heavy-weight Portland cement slurries for high pressure well cementing applications. Sedimentation issue is associated with high-density cement slurries which use high specific gravity solids such as weighting materials. This problem causes heterogeneity and density variation along the cemented sections. The main target of this work is to evaluate the use of perlite powder to address the sedimentation issue in the heavy weight geopolymer systems. Hematite-based Class F fly ash (FFA) geopolymer cement slurries with perlite concentrations of 0, 1.5, and 3% by weight of binder (BWOB) were prepared. The sedimentation problem was investigated using three techniques: API method, nuclear magnetic resonance (NMR), and computed tomography (CT) scan. The perlite effects on different geopolymer properties such as unconfined compressive strength (UCS), porosity, elastic and rheological properties were assessed. The results proved that perlite incorporation in high-density hematite-based FFA geopolymer significantly reduced sedimentation issue by increasing yield point and gel strength. NMR and CT scan showed that perlite decreases porosity and density variation across the geopolymer samples. The UCS increased with increasing perlite percentage from 0 to 3%. The measured Young’s moduli (YM) and Poisson’s ratios (PR) showed that the developed perlite based geopolymer systems are considered more flexible than Class G cement systems. It was found that the optimum perlite concentration is 3% BWOB for tackling sedimentation and developing a slurry with acceptable mixability and rheological properties.

The Metabolic Vulnerability Index: A Novel Marker for Mortality Prediction in Heart Failure

BackgroundInflammation and protein energy malnutrition are associated with heart failure (HF) mortality. The metabolic vulnerability index (MVX) is derived from markers of inflammation and malnutrition and measured by nuclear magnetic resonance spectroscopy. MVX has not been examined in HF. ObjectivesThe authors sought to examine the prognostic value of MVX in patients with HF. MethodsThe authors prospectively assembled a population-based cohort of patients with HF from 2003 to 2012 and measured MVX scores with a nuclear magnetic resonance scan from plasma collected at enrollment. Patients were divided into 4 MVX score groups and followed until March 31, 2021. ResultsThe authors studied 1,382 patients (median age: 78 years; 48% women). The median MVX score was 64.6. Patients with higher MVX were older, more likely to be male, have atrial fibrillation, and have a higher Meta-analysis Global Group in Chronic Heart Failure score. Higher MVX was associated with mortality independent of Meta-analysis Global Group in Chronic Heart Failure score, ejection fraction, and other prognostic biomarkers. Compared to those with the lowest MVX, the HRs for MVX groups 2, 3, and 4 were 1.1 (95% CI: 0.9-1.4), 1.5 (95% CI: 1.2-1.9), and 1.5 (95% CI: 1.2-1.9), respectively (Ptrend < 0.001). Measures of model improvement document the added value of MVX in HF for classifying the risk of death beyond the Meta-analysis Global Group in Chronic Heart Failure score and other biomarkers. ConclusionsIn this HF community cohort, MVX was strongly associated with mortality independently of established clinical factors and improved mortality risk classification beyond clinically validated markers. These data underscore the potential of MVX to stratify risk in HF.

The small molecule ACM-001 improves cardiac function in a rat model of severe cancer cachexia.

Cachexia, a common manifestation of malignant cancer, is not only associated with weight loss, but also with severe cardiac atrophy and impaired cardiac function. Here, we investigated the effects of ACM-001 (0.3 or 3mg/kg/d) in comparison to carvedilol (3 or 30mg/kg/d), metropolol (50 or 100mg/kg/d), nebivolol (1 or 10mg/kg/d) and tertatolol (0.5 or 5 mg/kg/d) on cardiac mass and function in a rat cancer cachexia model. Young male Wistar Han rats were inoculated with 108 Yoshida hepatoma AH-130 cells ip and treated once daily with verum or placebo by gavage. Cardiac function (echocardiography), body weight and body composition (NMR-Scans) were assessed. The hearts of animals were euthanized on day 11 (placebo and 3 mg/kg/d ACM-001) were used for signaling studies. Beta-blockers had no effect on tumour burden. ACM-001 reduced body weight loss (placebo: -34±2.4g vs 3mg/kg/d ACM-001: -14.8±8.4g, p=0.033). Lean mass wasting was attenuated (placebo: -16.5±2.34g vs 3mg/kg/d ACM-001: -2.4±6.7g, p=0.037), while fat loss was similar (p=0.4) on day 11. Placebo animals lost LVmass (-101±14mg), which was prevented only by 3mg/kg/d ACM-001 (7±25mg, 0<0.01 vs placebo). ACM-001 improved the EF (ΔEF: placebo: -24.3±2.6, 3mg/kg/d ACM-001: 0.1±2.9, p<0.001). Cardiac output was 50% lower in the placebo group (-41±4mL/min) compared to baseline, while 3mg/kg/d ACM-001 preserved cardiac output (-5±8, p<0.01). The molecular mechanisms involve inhibition of protein degradation and activation of protein synthesis pathways. This study shows that 3mg/kg/d ACM-001 restores the anabolic/catabolic balance in cardiac muscle leading to improved function. Moreover, not all beta-blockers have similar effects. This article is protected by copyright. All rights reserved.

Investigations of fracture behavior and pore structure change in pulse fracturing for cement block

Pulse fracturing can reduce fracture initiation pressure and increase stimulation effectiveness. To investigate the effect of frequency and amplitude on fracture propagation behavior in pulse fracturing, tri-axial experiments with acoustic emission (AE) monitoring are applied. The results demonstrate that pulse fracturing can generate mixed mode fractures, and the distinct deviation of the fracture propagation near-wellbore can be seen for pulse fracturing. Both pulse frequency and amplitude are critical parameters for the propagation path, measured AE accounts, accumulative energy and pore connectivity. The increase in amplitude is beneficial for large fracturing energy, but the increase in frequency is not necessarily helpful for fracture effectiveness. The harmony between the rock and pump frequency can yield the largest acoustic events and pore connectivity. The pore structure and microfracture change of rock before and after pulse fracturing at different distances are measured with nuclear magnetic resonance (NMR) and CT scans, indicating that pulse fracturing has a strong capability to create a larger stimulated area than the monotonic fracturing model. In addition, obvious microfracture generation and pore space expansion can be seen near the injection port. However, the pore structure comparison indicates that the pulse fracturing mode mainly improves the scale of macropores, which is primarily because of the relatively small pulse fracturing parameters used in these experiments. Thus, this study provides an understanding of pulse frequency and amplitude effects for stimulation effectiveness related to pulse fracturing of tight reservoirs.

The microbial growth potential of antiscalants used in seawater desalination

20 years since the first report on the biofouling potential of chemicals used for scale control, still, antiscalants with high bacterial growth potential are used in practice. Evaluating the bacterial growth potential of commercially available antiscalants is therefore essential for a rational selection of these chemicals. Previous antiscalant growth potential tests were conducted in drinking water or seawater inoculated with model bacterial species which do not represent natural bacterial communities. To reflect better on the conditions of desalination systems, we investigated the bacterial growth potential of eight different antiscalants in natural seawater and an autochthonous bacterial population as inoculum. The antiscalants differed strongly in their bacterial growth potential varying from ≤ 1 to 6 μg easily biodegradable C equivalents/mg antiscalant. The six phosphonate-based antiscalants investigated showed a broad range of growth potential, which depended on their chemical composition, whilst the biopolymer and the synthetic carboxylated polymers-based antiscalants showed limited or no significant bacterial growth. Moreover, nuclear magnetic resonance (NMR) scans enabled antiscalant fingerprinting, identifying components and contaminants, providing a rapid and sensitive characterization, and opening opportunities for rational selection of antiscalants for biofouling control.

The effect of unilateral adrenalectomy on patients with primary bilateral macronodular adrenal hyperplasia

PurposeTo evaluate the long-term effect of unilateral adrenalectomy (uADX) on patients with primary bilateral macronodular adrenal hyperplasia (PBMAH).MethodsWe retrospectively reviewed 29 patients (including 11 men and 18 women) with PBMAH and Cushing’s syndrome (CS) between 2005 and 2019 who underwent uADX in our center. Clinical symptoms, serum cortisol (8:00 a.m., 4:00 p.m., and 0:00 a.m.), 24 h urinary free cortisol (UFC), computed tomography (CT) scan of the adrenal gland, and pituitary nuclear magnetic resonance (MR) scan performed before and after operation were analyzed.ResultsThe median follow-up time was 39 (13–134) months. uADX decreased significantly at 24 h UFC (median: 357.14 vs. 89.50 ug/24 h, P < 0.001) and serum cortisol (8:00 a.m.) (median: 22.88 vs. 12.50 ug/uL, P < 0.001) 1 year after surgery. In total, 17 of 29 patients had normal UFC again 1 year after surgery, while one of them suffered a relapse after 61 months. However, uADX failed to decrease UFC to the normal range in the other patients. Ten of the remaining 12 uncured patients and the relapsed patient finally underwent contralateral adrenalectomy (cADX). The 24 h UFC of the patients who were cured (n = 17) after uADX was significantly lower than that of the uncured patients (n = 12) (222.30 vs. 579.10 ug/24 h, P = 0.011).ConclusionuADX may be an appropriate treatment for patients with mildly elevated cortisol, while contralateral adrenalectomy (cADX) may be required for patients with highly elevated cortisol. The level of 24 h UFC is helpful to predict patients’ prognosis.

Preparation and characterization of wet adhesives based on (poly (vinyl butyral-co-vinyl alcohol-co-vinyl acetate)/castor oil/styrene butadiene rubber) using gamma irradiation for trapping of reptiles and rodents

Wet adhesives from poly (vinyl butyral-co-vinyl alcohol-co-vinyl acetate), castor oil, and styrene butadiene rubber were prepared at variable compositions. These components were exposed to a certain range of irradiation dose for γ-rays. Wet adhesives were characterized by adhesion force, Fourier transform infrared, thermogravimetric analysis and derivative thermal gravimetric, gel permeation chromatography, proton nuclear magnetic resonance spectroscopy and scan electron microscopy. Results declared that dose and composition have significant effect on features of wet adhesives. Further, the adhesion force and thermal stability of wet adhesives improved by increasing the irradiation dose. Moreover, the adhesion force reached ~ 690 (kPa). The analysis of gel permeation chromatography showed that molecular weight of wet adhesive 48,921 (g/mol). The wet adhesives were exploited to trap reptiles and rodents. Through the results, it can be observed that the wet adhesives had good efficiency for trapping the reptiles and rodents. The results showed that the best sample of wet adhesive was from 98% of [poly (vinyl butyral-co-vinyl alcohol-co-vinyl (10%)/castor oil (90%))] to [2% of styrene butadiene rubber] at 30 kGy In conclusion, this study referred that this type of wet adhesive has an excellent ability to adhere and trap of reptiles and rodents such as geckos and mice respectively. Consequently, these wet adhesives could be utilized in pilot scale.

Lost circulation mitigation using modified enzyme induced calcite precipitation technique

Circulation loss is a very common and undesirable non-productive time (NPT) event that happens during the oil and gas well drilling operations. Many loss circulation materials (LCM) have been formulated and implemented in the process of gas and oil wells drilling to minimize or mitigate this problem. In-situ calcite precipitation in effective pores can restrict the movement of the water flow between the grains by forming bridges. In this study, different mixes of Enzyme-induced calcite precipitation (EICP) solution are studied and tested in the laboratory to mitigate lost circulation problem. EICP solution is primarily composed of urea, calcium chloride, magnesium chloride, Xanthan Gum, and urease enzyme. Different concentrations and compositions of reagents were tested. The properties of the created precipitates were examined through different techniques such as X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The combination that produced the highest amount of thermally stable calcite with a minimal amount of aragonite, along with the highest precipitation efficiency was further selected for lost circulation application. A solution containing 1M Urea, 0.9M CaCl 2 , 0.1M MgCl 2 , 1 g/L Xanthan Gum, and 3 g/L urease was considered as an optimum combination for an EICP process. Lost circulation experiments were carried out in core flooding experiments on a high permeable Indian Limestone sample at room and elevated temperature conditions with the optimum combination of EICP reagents. The permeability of the samples was measured before and after the treatment. Nuclear Magnetic Resonance (NMR) scan was also run before and after the treatment to determine the pore size redistribution. Results showed that the permeability of the samples was reduced by 99%, NMR results showed that the porosity of the samples was also reduced by 20%. • Investigation of the modified enzyme induced calcite precipitation as a lost circulation technique. • Investigation of incorporating magnesium in an EICP process to precipitate dolomite mineral. • Investigation of incorporating Xanthan Gum as a temperature stabilizer for an EICP reaction. • Coreflooding and NMR experiments with optimized EICP solution as a potential lost circulation material. • 99% reduction in permeability achieved with modified EICP process.

Shift of musical hallucinations to visual hallucinations after correction of the hearing deficit in a patient with Lewy body dementia: a case report

BackgroundMusical hallucinations are a particular type of auditory hallucination in which the patient perceives instrumental music, musical sounds, or songs. Musical hallucinations are associated with acquired hearing loss, particularly within the elderly. Under conditions of reduced auditory sensory input, perception-bearing circuits are disinhibited and perceptual traces released, implying an interaction between peripheral sensory deficits and central factors related to brain dysfunction.Case presentationA 71-year-old Caucasian man with hearing loss complained of memory difficulties and resting tremor of the right upper limb in the previous 2 years. He already had difficulties in instrumental activities of daily life. Neurological examination showed Parkinsonian signs and hypoacusia. Neuropsychological examination identified deficits in executive functions and memory tests. Brain computerized tomography and nuclear magnetic resonance scans showed mild cortical and subcortical atrophy. The clinical diagnosis of possible dementia with Lewy bodies was established. Five years later, the patient began complaining of musical hallucinations. There had been no previous change in medication. An otorhinolaryngologist diagnosed age-related hearing loss and prescribed bilateral hearing aids. After using the hearing aids, the patient did not hear the songs any longer, only some tinnitus, described as a whistle. However, at the same time, the patient started experiencing visual hallucinations he never had before.DiscussionTo our knowledge, the immediate shift of hallucinations from one sensory modality to another sensory modality when perception is improved has not been previously described. This report emphasizes the interaction between brain pathology and sensory deficits for the genesis of hallucinations, and reinforces the theory that attention and control networks must couple properly to the default mode network, as well as integrate and select adequately peripheral signals to the somatosensory cortices, in order to keep a clear state of mind.ConclusionThe clinician should bear in mind and let the patient know that improving one sensory modality to ameliorate hallucinations may sometimes paradoxically lead to hallucinations in a different sensory modality.

Reduction of Breakdown Pressure by Filter Cake Removal Using Thermochemical Fluids and Solvents: Experimental and Numerical Studies.

The process of well cleanup involves the removal of an impermeable layer of filter cake from the face of the formation. The inefficient removal of the filter cake imposes difficulty on fracturing operations. Filter cake’s impermeable features increase the required pressure to fracture the formation. In this study, a novel method is introduced to reduce the required breakdown pressure to fracture the formation containing the water-based drilling fluid filter cake. The breakdown pressure was tested for five samples of similar properties using different solutions. A simulated borehole was drilled in the core samples. An impermeable filter cake using barite-weighted drilling fluid was built on the face of the drilled hole of each sample. The breakdown pressure for the virgin sample without damage (filter cake) was 6.9 MPa. The breakdown pressure increased to 26.7 MPa after the formation of an impermeable filter cake. Partial removal of filter cake by chelating agent reduced the breakdown pressure to 17.9 MPa. Complete dissolution of the filter cake with chelating agents resulted in the breakdown pressure approximately equivalent to the virgin rock breakdown pressure, i.e., 6.8 MPa. The combined thermochemical and chelating agent solution removed the filter cake and reduced the breakdown pressure to 3.8 MPa. Post-treatment analysis was carried out using nuclear magnetic resonance (NMR) and scratch test. NMR showed the pore size redistributions with good communication between different pores after the thermochemical removal of filter cake. At the same time, there was no communication between the different pores due to permeability impairment after filter cake formation. The diffusion coupling through NMR scans confirmed the higher interconnectivity between different pores systems after the combined thermochemical and chelating agent treatment. Compressive strength was measured from the scratch test, confirming that filter cake formation caused added strength to the rock that impacts the rock breakdown pressure. The average compressive strength of the original specimen was 44.5 MPa that increased to 73.5 MPa after the formation of filter cake. When the filter cake was partially removed, the strength was reduced to 61.7 MPa. Complete removal with chelating agents removed the extra strength that was added due to the filter cake presence. Thermochemical and chelating agents resulted in a significantly lower compressive strength of 25.3 MPa. A numerical model was created to observe the reduction in breakdown pressure due to the thermochemical treatment of the filter cake. The result presented in this study showed the engineering applications of thermochemical treatment for filter cake removal.

Effects of molecular structure of polymeric surfactant on its physico-chemical properties, percolation and enhanced oil recovery

Polymeric surfactant can simultaneously thicken aquous phase and reduce water–oil interfacial tension (IFT), which makes it present a great application prospect in the oilfield taword enhanced oil recovery (EOR). There are two kinds of polymeric surfactant with different molecular structures are commonly used to realize the salt resistance, thermal endurance and shear resistance. However, the influence of the molecular structure of polymeric surfactant on their properties related on EOR are not well understood. In the work, we synthesized two kinds of polymeric surfactants with different molecular structure which respectively named intermolecular association molecule (IAM) and rigid chain molecule (RCM). Their physico-chemical properties, porous media transportation and EOR are compared with a series of experiments. It is found that the hydrodynamic characteristic sizes and retention of IAM are higher than those of RCM via the membrane filtration test and nuclear magnetic resonance (NMR) scan. These features make IAM have a larger resistance factor and residual resistance factor than RCM and hydrolyzed polyacrylamide (HPAM) in the same viscosity. Compare to HPAM with shear thinning, RCM presents a Newtonian fluid region and IAM presents a shear thickening region when the shear rate is lower than 1 s−1. The spatial structure of IAM can pack oil drop into its network, which make it easy to form oil-in-water-in-oil (O/W/O) emulsions. Moreover, the concentration and water–oil ratio (WOR) rarely affect the stability of IAM emulsions once the intermolecular association generated. The increamental oil recovery factor of IAM is 17.5% after water flooding in the three-layer core flooding experiments with the permeability of 500 mD, 1500 mD and 3000 mD at 55℃, which is higher than that of 14.5% for RCM and 11.4% for HPAM.

Evaluating drilling fluid infiltration in porous media – Comparing NMR, gravimetric, and X-ray CT scan methods

The infiltration of drilling fluids into underground rocks during drilling can cause adverse effects such as underground fluid loss, formation damage, and borehole collapse. An effective filter cake formed by the drilling fluid on the borehole wall can minimize such adverse effects to a degree that is dependent on the characteristics of the drilling fluid. For this reason, drilling fluids are routinely screened in the laboratory based on the sealing properties of their filter cakes. However, there appear not to be a universally adopted method for characterizing filter cakes. This study utilizes a nuclear magnetic resonance (NMR) approach to characterize filter cakes and then compares the result with some existing methods. Fluid loss tests were conducted to form filter cakes over four consolidated sandstone and carbonate rock samples. NMR measurements were conducted pre and post filter cake deposition. NMR measurements of filter cake porosity and infiltrated solids were compared with those from conventional methods such as gravimetric and X-ray computer tomography (CT) measurements. The results obtained from the three methods show significantly different values. To resolve this, cross correlations plots were made between measurements obtained from the three methods and the measured cake thickness. NMR measured porosity and infiltrated solids showed an excellent correlation with the measured cake thickness compared to the other two methods. However, the porosity values from NMR is significantly lower than the values obtained from the other methods. Through sensitivity analyses, we provide reasons why values from other methods are high and not as representative as the NMR method. We also gave a detailed explanation why NMR method is more accurate and useful compared to the other methods.

The Digitalization of Bottle Tests Nuclear Magnetic Resonance Evaluation of Emulsion Stability

Bottle tests are the preferred meth-od to test petroleum emulsion stability in the industry today. A new technique using nuclear magnetic resonance (NMR) is available to evaluate both stability and demulsification behavior of emulsions. The NMR scans the water fraction throughout the entire length of the emulsion sample. These rapid measurements are designed to dynamically probe the emulsion, capturing its separation as a digital image. This case study presents the ways NMR has helped predict the effects of future well line-up changes. Introduction Emulsion stability negatively impacts oil processing operations and plant design. The assessment of emulsion stability is performed at wellheads and gas/oil separation plants (GOSPs). Bottle tests are largely used for emulsion assessment, due to their simplicity and low cost. These tests depend on the visual identification of the separated water layer as the only quantifiable parameter. NMR is one of the alternative methods for emulsion assessment that can pro-vide information for all emulsion components. These components include the water layer; the oil/water interface - including the rag layer (the dense-pack zone [DPZ] of droplets above the interface); the remaining water-in-oil emulsion; and the dry-oil continuous phase. The DPZ - or rag layer - is of particular importance for oil processing, as its occurrence in separation vessels can lead to process upsets, resulting in excessive concentration of oil at the vessel’s water outlets. This interfacial phenomenon is particularly critical in the production of heavy oils, oils with high solid content, and oils forming highly stable emulsions. NMR is not only capable of measuring the water fraction throughout the entire emulsion sample, but can also provide a digital image of the water separating in the sample. More advanced NMR analyses are able to determine the water droplet size distribution (DSD) in the emulsion, and how the distribution changes during separation. It is also possible to obtain information on the droplet sizes at each position in the sample, as they change in time. Bottle tests are limited to the visualization of the free-water layer. Measurement errors are common if the oil/water interface is not clear. Unlike the NMR, any water still emulsified in the oil cannot be measured as it is not visible. The formation of the rag layer cannot be identified either. In addition, the efficiency of separation calculated from bottle test results, or emulsion separation index (ESI), requires knowledge of the water cut of the sample. The production water cut can be provided by the oil-processing operations, but the value is hardly the same found at sampling points. If the water cut is not known, it needs to be accurately measured in the sample after the bottle test. Usually the total amount of water is measured after centrifugation. It is difficult to guarantee that the emulsion is fully separated, as some droplets could still be unresolved at the interface. Another test limitation is the determination of separation efficiency when the water quality is poor. The presence of an oil-in-water emulsion could be the cause of cloudiness, contributing to an inefficient separation. But most of all, no readings can be made if the emulsion does not separate spontaneously. With NMR it is possible to determine the sedimentation rate of water droplets, even if no coalescence takes place (and no free-water layer is formed).

The effect of pore structure complexity and saturation history on the variations of acoustic velocity as function of brine and oil saturation in carbonates

Time lapse seismic is a major technique that has been successfully implemented to monitor reservoir dynamics (such as changes in fluid saturation) in sandstones but its applicability in carbonate rocks is not well understood yet. This study aims to improve our understanding of the time lapse seismic signature in carbonates oil reservoirs by investigating how acoustic velocity changes as a result of variations in the brine and oil saturation. To this scope, we utilize a core flooding system to perform brine-oil displacement experiment in three reservoir carbonate samples, while monitoring the acoustic velocity as function of brine saturation (Sw) changes. The fluid displacement experiment included injection of oil into the fully brine saturated samples until reaching irreducible brine saturation, followed by injection of brine until reaching the residual oil saturation. We also characterize the pore structure complexity of the samples using nuclear magnetic resonance (NMR) and micro-CT scans to investigate its effect on the velocity-saturation relationship. We finally compare the measured acoustic velocity as function of saturation with the predictions of Gassmann theory while considering both uniform and patchy fluid distribution styles.Our results show that both P- and S-wave velocity (Vp and Vs respectively) decrease as oil displaces brine and then they both increase as brine displaces oil. Nevertheless, the velocity-saturation relationship exhibits a hysteresis: velocities measured at a given saturation during brine injection tend to be higher than those measured during oil injection. Our analysis shows that the Vp-Sw trend during oil injection into brine saturated samples follows the lower bound predicted by Gassmann theory (i.e., uniform fluid distribution), while the brine flooding data follows the upper bound of Gassmann theory (i.e., patchy fluid distribution). The transition from the uniform to patchy fluids distribution seems to occur around the irreducible brine saturation. Since oil production or enhanced oil recovery can be represented by the process of brine displacing oil, our results suggest that patchy fluid distribution should be considered in Gassmann theory when performing feasibility studies to predict changes in Vp as function of saturation changes. This study also highlights the importance of pore structure in controlling the changes of saturation and the corresponding changes in acoustic velocity. Larger changes and hysteresis in the measured velocity as function of saturation seem to correlate with lower pore stiffness (i.e., more micro cracks and less content of intraparticle rounded pores).

Determination of the optimum wormholing conditions in carbonate acidizing using NMR

The current optimum wormhole injection rate during acid stimulation treatment in a carbonate formation is defined as the injection rate that creates a dominant wormhole with the minimum acid volume. Wormholes are created to connect the reservoir to the wellbore by bypassing the drilling fluid damage and to enhance the wellbore productivity by increasing the effective wellbore radius in carbonate formations. Currently, the pressure drop and computed tomography scan (CT scan) are used to define the acid optimum injection rate and wormhole shape in the stimulated carbonate rock cores. However, these two techniques assess the interconnectivity of the created wormhole to the rest of the pore system in the reservoir in a coarse way.In this paper and for the first time new definitions and new approach to the optimum injection rate and wormhole evaluation during carbonate stimulation are introduced. Coreflooding experiments were performed using 3-inch Indiana limestone cores at 100 °C at different injection rates. A suite of stimulation fluids such as emulsified acid, hydrochloric (HCl) acid, gelled HCl acid systems based on polymers and viscoelastic surfactant (VES), and chelating agents were used in this study. Nuclear Magnetic Resonance (NMR) was used to evaluate the efficiency of different stimulation fluids in creating wormholes and their interconnectivity with the surrounding pore distributions in the rock. A new dimensionless number, pore interconnectivity number, is introduced to describe the interconnectivity between the created wormhole and the rest of the pore size distributions in the rock. Optimum wormhole shape is determined at the highest interconnectivity number. The optimum injection rate for a specific fluid can also be determined at the highest interconnectivity number.Detailed NMR scanning of the core was found to be a good assessing tool for the type of the stimulation fluid and locating the optimum wormholing generating conditions. For example, using a 3-inch length Indiana limestone core, conventional coreflooding experiments showed that 2 cm3/min injection rate generates the minimum acid volume HCl/VES acid system, however, NMR scan showed an injection rate of 3 cm3/min generates the highest pore interconnectivity for the wormhole. Gelled acidizing fluids such as HCl based on polymers created wormholes that were clearly identified by CT scan and pressure drop but the NMR scan showed that these wormholes are completely isolated from the rest of the surrounding pore system due to polymer residue plugging the pores. This isolation will reduce the production rate due to minimal radial fluid entry at the wormhole surface. Radial flooding experiments through the wormhole and production from the side of the core confirmed the findings of NMR scan regarding the interconnection between the wormholes and other pores in the rock. Strong relationship was found between the interconnectivity number and core radial permeability around the wormhole.

Prognostic factors for postoperative visual outcome in surgically treated suprasellar meningiomas

The prognosis of postoperative visual acuity in patients with surgically treated suprasellar meningiomas is influenced not only by the size and precise localization of meningiomas in the optochiasmatic region and their compressive effect, but also by certain parameters, such as the age of patient, duration of symptoms, and preoperative visual acuity. The purpose of this study was to analyze the influence of these factors on postoperative visual acuity in the patients with surgically treated optochiasmatic meningioma as well as to determine their prognostic value in the recovery of visual function after surgery. The study sample consisted of 43 pati- ents operated for suprasellar meningioma. All tumors were dia- gnosed by computed tomography or nuclear magnetic resonance scans. Visual acuity was analyzed both before surgery and six months after surgery. The effects of age, preoperative Visual loss, duration of visual symptoms and tumor size on visual outcome were analyzed. Postoperative improvement of visual acuity was observed in 50% of eyes (68.4% of patients). Visual outcome was better in the younger patients. The patients with better preoperative visual acuity had better postoperative visual acuity outcome. Chances of achieving better postoperative visual function and favorable tumor resection outcome were inversely proportional to the increased length of history of disease and tumor size. Postoperative visual acuity prognosis in suprasellar meningioma surgery was favorably affected by the mean duration of symptoms of less than 24 months, tumor size less than 30 mm. and preoperative visual acuity loss below 0.1.

Muscle strength recovery versus semitendinosus and gracilis tendon regeneration after harvesting for anterior cruciate ligament reconstruction

Twenty consecutive, chronic and isolated anterior cruciate ligament (ACL) lesions that underwent reconstruction with quadrupled semitendinosus (ST) and gracilis (G) were prospectively examined to compare tendon regeneration and muscle strength recovery. Twenty consecutive axial nuclear magnetic resonance (NMR) scans were done after 1 month, 6 months and 2 years from surgery. A CybexII was used to evaluate concentric strength deficits both in flexion and in internal tibia rotation at 6 months and 2 years. At 2 years, an NMR signal comparable to the contralateral was present in 14 (70%) cases and absent in 6 (30%). Semitendinosus tendon exceeded the meniscal plateau since the first month, while the G tendon crossed the joint line only after 6 months. However, the distal-end insertions of both tendons were always significantly more proximal than the contralateral normal side (ST: P = .002; G: P = .003). In case of tendon regeneration, flexion deficit was not significant after 6 months, while internal tibia rotation deficit became not significant only after 2 years. In case of non-regeneration, a flexion deficit was present after 6 months [15.5% (P = .05)] but not after 2 years, while internal tibial rotation deficit was significant both after 6 months [30.3% (P < .001)] and 2 years [24.3% (P = .03)]. In case of tendon regeneration, isokinetic evaluation showed a non-significant deficit in both flexion and internal rotation strength after ACL reconstruction with ST and G. At the 2-year follow-up, none of the 6 patients without tendon regeneration found any impairment in their sport activities despite the loss of internal rotation strength.

Peptide–Micelle Hybrids Containing Fasudil for Targeted Delivery to the Pulmonary Arteries and Arterioles to Treat Pulmonary Arterial Hypertension

This study investigates the respirability and efficacy of peptide-micelle hybrid nanoparticles as carriers for inhalational therapy of pulmonary arterial hypertension (PAH). CARSKNKDC (CAR), a cell-penetrating and lung-homing peptide, conjugated polyethylene glycol-distearoyl-phosphoethanolamine micelles containing fasudil, an investigational anti-PAH drug, were prepared by solvent evaporation method and characterized for various physicochemical properties. The pharmacokinetics and pharmacological efficacy of hybrid particles containing fasudil were evaluated in healthy rats and monocrotaline-induced PAH rats. CAR micelles containing fasudil had an entrapment efficiency of approximately 58%, showed controlled release of the drug, and were monodispersed with an average size of approximately 14 nm. Nuclear magnetic resonance scan confirmed the drug's presence in the core of peptide-micelle hybrid particles. Compared with plain micelles, CAR peptide increased the cellular uptake by approximately 1.7-fold and extended the drug half-life by approximately fivefold. The formulations were more prone to accumulate in the pulmonary vasculature than in the peripheral blood, which is evident from the ratio of the extent of reduction of pulmonary and systemic arterial pressures. On the whole, this study demonstrates that peptide-polymer hybrid micelles can serve as inhalational carriers for PAH therapy.

Acute hypophysitis and hypopituitarism in early syphilitic meningitis in a HIV-infected patient: a case report

BackgroundSexually transmitted diseases and most notably syphilis-infections are rising amongst men who have sex with men. In HIV-co-infected patients, an accelerated clinical course of syphilis neurological involvement is known.Case presentationA 46 year old HIV-positive male patient came in to our emergency department in the late evening with acute fever, rapidly progressive cephalgia and photophobia. Palmar skin efflorescence was evocative of an active syphilis infection. A reactive Treponema pallidum particle agglutination (TPPA) assay with positive Treponema pallidum-specific IgG/IgM immunofluorescence as well as a highly reactive Veneral diseases research laboratory (VDRL) test confirmed the diagnosis. Liquor pleocytosis, liquor protein elevation and a highly positive VDRL test in cerebrospinal fluid (CSF) were interpreted in context of the clinical symptoms as neurosyphilitic manifestations within an early syphilis infection (stage II). Cranial nuclear magnetic resonance scans of the sella turcica, which were performed due to low thyroidea stimulation hormone (TSH) and thyroxin levels, showed signs of hypophysitis such as pituitary gland enlargement and inhomogeneous contrast enhancement. Advanced endocrine laboratory testing revealed hypopituitarism. Fourteen days of intravenous ceftriaxone treatment and levothyroxine- and hydrocortisone-substitution led to complete disappearance of all clinical symptoms. Two months later, nuclear magnetic resonance scan showed normal pituitary size and that the syphilis serology had normalized.ConclusionWe report to the best of our knowledge the first case of a HIV-positive patient with acute hypophysitis and hypopituarism due to early neurosyphilis infection. Ceftriaxone treatment and levothyroxine- and hydrocortisone-substitution led to the disappearance of all clinical symptoms. We strongly recommend to exclude syphilis infection in every clinical situation unclear in HIV-patients, especially when additional risk factors are known.

Evaluation of extensive initial staging procedure in intermediate/high‐risk melanoma patients

Early diagnosis and treatment of metastases have been shown to improve overall survival of melanoma patients. The purpose of this study was to evaluate the impact of extensive initial staging, including positron emission tomography (PET) scan on the management of melanoma patients. Forty-three patients with intermediate/poor prognosis primary melanoma benefited from complementary excision and sentinel lymph node biopsy (SLB) after clinical and paraclinical staging (computed tomography, nuclear magnetic resonance and whole body fluorodeoxyglucose PET scan). No systemic metastases were demonstrated, while the SLB procedure emphasized the presence of regional lymph node metastases in 10 patients as suggested by the PET scan in four patients (sensitivity of the PET scan 40%). These 10 patients with early diagnosed lymph node involvement benefited from early surgery and were included in adjuvant treatment protocols. A secondary primary cancer was fortuitously diagnosed and treated early in two patients. The development of new adjuvant therapies and therapeutic procedures (specific and non-specific immunotherapy, gamma-knife radiosurgery, etc.) now raises the relevance of extensive staging in intermediate/poor prognosis melanoma patients. We confirm in our series that PET scan is not useful to detect micrometastasis and cannot replace SLB in initial regional staging. However, we show in our study that 12 of 43 patients were treated early or were included early in treatment protocols thanks to the extensive staging procedure. Nevertheless, it seems important to evaluate through larger prospective trials the real impact of these early diagnoses and new treatments on overall survival before defining new diagnostic and therapeutic guidelines.