Injection Of Hydrochloric Acid Research Articles

Controls of low injectivity caused by interaction of reservoir and clogging processes in a sedimentary geothermal aquifer (Mezőberény, Hungary)

Low injectivity is often experienced in geothermal doublets installed in sandstone reservoirs. This even led to a shutdown of the Mezőberény (Hungary) geothermal site. An on-site campaign was carried out in January 2021 to prepare a stimulation aiming to enhance the transmissivity of the sedimentary reservoir and the near-wellbore zone of this site. Previous studies have concluded that insufficient injectivity may be linked to a high skin effect in the near well-bore zone and pore clogging in combination with the low net sandstone content of the fluvio-deltaic reservoir. A chemical soft stimulation based on the injection of hydrochloric acid (HCl) was successfully used to unclog and recover the well injectivity. Despite such empirical evidence, the geochemical mechanisms leading to both, detrimental formation of clogging and the HCl-driven transmissivity restoration, have not yet been elucidated. This work presents the results of a novel analysis aiming at (a) predicting the dominant type of clogging forming in the near-well bore zone; (b) quantifying the drop in hydraulic conductivity as clogging occurs; and (c) supporting the optimization of the HCl dosage during the chemical soft stimulation. The study is supported by new experimental datasets never presented before from the Mezőberény site and a geochemical model set-up simulating the main mechanisms involved in the clogging and unclogging processes. It is concluded that the biofilm formation was the dominant, while the precipitation of calcite and amorphous ferrihydrite—later reduced to magnetite by microbes—was the secondary clogging mechanism: In the long-term (yearly scale) simulating the hydraulic conductivity showed a decline with forming scales; therefore, biofilm was presumably responsible for the experienced rapid (1 month) clogging. When modelling the chemical stimulation, the estimated amount of precipitated minerals was dissolved already with 2.5 mol of HCl per liter of water (~ 10 m/m%). Therefore, the 20 m/m% of HCl chosen during the field campaign might had a beneficial effect dissolving the potentially higher amount of scaling and/or the carbonate minerals of the matrix near the wellbore. Overall, it is concluded that the chemical and the microbial analyses together with the geochemical model were critical to tailor the remediation attempts and to propose further development or reconstruction of the surface system before going into operation to prevent recurrent impairments. Our findings highlight the importance of interactions of various clogging mechanisms with each other as well as with the reservoir processes and provide approaches to tackle the issue of injectivity drop by characterizing and quantifying their effects.

Cepharanthine Dry Powder Inhaler for the Treatment of Acute Lung Injury.

Severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) induces a severe cytokine storm that may cause acute lung injury/acute respiratory distress syndrome (ALI/ARDS) with high clinical morbidity and mortality in infected individuals. Cepharanthine (CEP) is a bisbenzylisoquinoline alkaloid isolated and extracted from Stephania cepharantha Hayata. It exhibits various pharmacological effects, including antioxidant, anti-inflammatory, immunomodulatory, anti-tumor, and antiviral activities. The low oral bioavailability of CEP can be attributed to its poor water solubility. In this study, we utilized the freeze-drying method to prepare dry powder inhalers (DPI) for the treatment of acute lung injury (ALI) in rats via pulmonary administration. According to the powder properties study, the aerodynamic median diameter (Da) of the DPIs was 3.2 μm, and the in vitro lung deposition rate was 30.26; thus, meeting the Chinese Pharmacopoeia standard for pulmonary inhalation administration. We established an ALI rat model by intratracheal injection of hydrochloric acid (1.2 mL/kg, pH = 1.25). At 1 h after the model's establishment, CEP dry powder inhalers (CEP DPIs) (30 mg/kg) were sprayed into the lungs of rats with ALI via the trachea. Compared with the model group, the treatment group exhibited a reduced pulmonary edema and hemorrhage, and significantly reduced content of inflammatory factors (TNF-α, IL-6 and total protein) in their lungs (p < 0.01), indicating that the main mechanism of CEP underlying the treatment of ALI is anti-inflammation. Overall, the dry powder inhaler can deliver the drug directly to the site of the disease, increasing the intrapulmonary utilization of CEP and improving its efficacy, making it a promising inhalable formulation for the treatment of ALI.

Inhibition of Prostaglandin F2α Receptors Exaggerates HCl-Induced Lung Inflammation in Mice.

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are severe respiratory disorders that are caused by aspiration, sepsis, trauma, and pneumonia. A clinical feature of ALI/ARDS is the acute onset of severe hypoxemia, and the mortality rate, which is estimated at 38–50%, remains high. Although prostaglandins (PGs) are detected in the bronchoalveolar lavage fluid of patients with ALI/ARDS, the role of PGF2α in ALI remains unclear. We aimed to clarify the role of PGF2α/PGF2α receptor (FP) signaling in acid-induced ALI using an FP receptor antagonist, AL8810. Intratracheal injection of hydrochloric acid (HCl) increased neutrophil migration into the lungs, leading to respiratory dysfunction. Pre-administration of AL8810 further increased these features. Moreover, pre-treatment with AL8810 enhanced the HCl-induced expression of pro-inflammatory cytokines and neutrophil migratory factors in the lungs. Administration of HCl decreased the gene expression of lung surfactant proteins, which was further reduced by co-administration of AL8810. Administration of AL8810 also increased lung edema and reduced mRNA expression of epithelial sodium channel in the lungs, indicating that AL8810 reduced fluid clearance. Furthermore, AL8810 also increased lipopolysaccharide-induced expression of adhesion molecules such as intracellular adhesion molecule-1 and E-selectin in human umbilical vein endothelial cells. These results indicate that inhibition of FP receptors by AL8810 exacerbated HCl-induced ALI.

Positional Therapy and Regional Pulmonary Ventilation.

Prone ventilation redistributes lung inflation along the gravitational axis; however, localized, nongravitational effects of body position are less well characterized. The authors hypothesize that positional inflation improvements follow both gravitational and nongravitational distributions. This study is a nonoverlapping reanalysis of previously published large animal data. Five intubated, mechanically ventilated pigs were imaged before and after lung injury by tracheal injection of hydrochloric acid (2 ml/kg). Computed tomography scans were performed at 5 and 10 cm H2O positive end-expiratory pressure (PEEP) in both prone and supine positions. All paired prone-supine images were digitally aligned to each other. Each unit of lung tissue was assigned to three clusters (K-means) according to positional changes of its density and dimensions. The regional cluster distribution was analyzed. Units of tissue displaying lung recruitment were mapped. We characterized three tissue clusters on computed tomography: deflation (increased tissue density and contraction), limited response (stable density and volume), and reinflation (decreased density and expansion). The respective clusters occupied (mean ± SD including all studied conditions) 29.3 ± 12.9%, 47.6 ± 11.4%, and 23.1 ± 8.3% of total lung mass, with similar distributions before and after lung injury. Reinflation was slightly greater at higher PEEP after injury. Larger proportions of the reinflation cluster were contained in the dorsal versus ventral (86.4 ± 8.5% vs. 13.6 ± 8.5%, P < 0.001) and in the caudal versus cranial (63.4 ± 11.2% vs. 36.6 ± 11.2%, P < 0.001) regions of the lung. After injury, prone positioning recruited 64.5 ± 36.7 g of tissue (11.4 ± 6.7% of total lung mass) at lower PEEP, and 49.9 ± 12.9 g (8.9 ± 2.8% of total mass) at higher PEEP; more than 59.0% of this recruitment was caudal. During mechanical ventilation, lung reinflation and recruitment by the prone positioning were primarily localized in the dorso-caudal lung. The local effects of positioning in this lung region may determine its clinical efficacy.

Computational fluid dynamics investigation for austenitic AISI 904L stainless steel corrosion in a biodiesel stream piping

A Brazilian biodiesel plant uses the transesterification of soybean oils with the methanol and sodium methoxide catalyst excess to convert these oils into alkyl esters and glycerin. Hydrochloric acid solution is injected in the piping to neutralize free NaOH and reduce saponification of oils. After the hydrochloric acid solution, several failures of pipelines of AISI 316L and 904L steels were registered. The objective of this work is to study the austenitic stainless steel corrosion observed in the downstream piping the hydrochloric acid injection, applying computational fluid dynamics and to evaluate pH and chloride profiles using different geometries for the acid solution injection in order to avoid or mitigate the corrosive attack. The obtained results showed a good agreement with in situ observations of the pipe degradation. All the studied geometries presented evidence of a weak mixture between the polar and non‐polar species, even under turbulent flow. The elbow geometry is more effective to reduce the local corrosive attack compared to two other simulated geometries.

Regulating autonomic nervous system homeostasis improves pulmonary function in rabbits with acute lung injury

BackgroundThis study aimed to investigate the effects of regulating autonomic nervous system (ANS) homeostasis by inhibiting sympathetic hyperactivity and/or enhancing parasympathetic activity on pulmonary inflammation and functional disturbance.MethodsAn animal model of acute lung injury (ALI) was established in rabbits by an intratracheal injection of hydrochloric acid (HCl) in rabbits. Animals in control groups were received saline or HCl only, and the others received both HCl and followed treatments: vagus nerve stimulation (VNS), intravenous injection of tetrahydroaminoacridine (THA), or stellate ganglion block (SGB). The effects of different treatments on the changes in autonomic nervous system homeostasis, pulmonary and systemic inflammation, and functional disturbance were detected.ResultsSympathetic nervous activity was higher than parasympathetic nervous activity in rabbits after HCl aspiration, as demonstrated by the significant changes in the discharge frequency of cervical sympathetic/vagus trunk, and heart rate variability. VNS, THA and SGB could significantly alleviate the changes of ANS induced by HCl aspiration and improved the pulmonary function, especially for SGB treatment.ConclusionsThe disturbance of ANS homeostasis is attributed to a predominance of SNS activity. Administration of VNS, THA and SGB are capable to regulate disequilibrium of the ANS in rabbits with HCl-induced ALI and SGB is supposed to be the most effective approach.

Porous media investigation before and after hydrochloric acid injection on a pre-salt carbonate coquinas sample

Porous space characterization of carbonate rocks is an important aid in petroleum exploration from carbonate reservoir. In this study, X-ray microtomography technique was applied to evaluate total porosity of a coquina sample extracted from pre-salt reservoir, in Brazil, before and after acid injection. Two image processing program were used in order to assess performance. The results showed that microtomography has potential to compute porosity of coquina samples and provides information about rock porous network.

Time‐dependent changes in bladder function and plantar sensitivity in a rat model of fibromyalgia syndrome induced by hydrochloric acid injection into the gluteus

To examine the correlation between muscular pain and bladder hypersensitivity in order to clarify the pathogenesis of comorbidity of bladder pain syndrome/interstitial cystitis with other chronic pain conditions such as fibromyalgia syndrome (FMS). Under isoflurane anaesthesia, 0.2 mL of hydrochloric acid (HCl) solution (pH 4.0) was injected into the bilateral gluteus muscles of female Sprague-Dawley rats to produce an FMS model, as the gluteus is one of the specific tender points in patients with FMS. Control rats received saline injection (0.2 mL). The mechanical sensitivity of the plantar was evaluated using the mean number of bilateral hindlimb withdrawals in response to tactile stimulation with a 2.0-g von Frey filament at 1, 2 and 3 weeks after the HCl injection. In a separate rat group, cystometry was performed with the rats awake during saline infusion (0.06 mL/min) into the bladder before and after 1% lidocaine injection (0.2 mL) into the bilateral gluteus 1, 2 and 3 weeks after the HCl injection. The mean number of hindlimb withdrawals was significantly higher in FMS rats than in controls at 1 and 2 weeks. Using cystometry, we found that the intercontraction interval (ICI) and voided volume (VV) were significantly lower in FMS rats than in controls at 1 and 2 weeks. In addition, the voiding threshold pressure, ICI and VV were significantly higher after lidocaine injection in FMS rats, but not in controls, at 1 and 2 weeks. HCl injection (pH 4.0) into the gluteus can induce plantar hypersensitivity and urinary frequency for up to 2 weeks after the injection, suggesting that somatic (gluteus)-to-visceral (bladder) cross-sensitization might underlie bladder hypersensitivity in patients with FMS. Moreover, intervention at specific tender points outside the bladder could be effective in treating urinary frequency because lidocaine injection into the gluteus normalized bladder function in FMS rats for up to 2 weeks.

Proton Acts as a Neurotransmitter for Nicotine-Induced Adrenergic and Calcitonin Gene-Related Peptide-Containing Nerve-Mediated Vasodilation in the Rat Mesenteric Artery

Nicotine stimulates presynaptic nicotinic acetylcholine receptors in perivascular adrenergic nerves and releases unknown transmitter(s) that activate transient receptor potential vanilloid-1 (TRPV1) located on calcitonin gene-related peptide (CGRP)-containing (CGRPergic) nerves, resulting in vasodilation. The present study investigated a potential transmitter transmitting between perivascular adrenergic nerves and CGRPergic nerves. Rat mesenteric vascular beds without endothelium were contracted by perfusion with Krebs' solution containing methoxamine, and the perfusion pressure and pH levels of the perfusate were measured. Nicotine perfusion for 1 min induced concentration-dependent vasodilation and lowered pH levels, which were abolished by cold-storage denervation of preparations, guanethidine (adrenergic neuron blocker), and mecamylamine (nicotinic alpha(3)beta(4)-acetylcholine receptor antagonist). Capsazepine (TRPV1 antagonist) blunted nicotine-induced vasodilation, but had no effect on the reduction of pH. Injection of hydrochloric acid (HCl) and perfusion of Krebs' solution at low pH (6.0-7.2) induced vasodilation. HCl-induced vasodilation was inhibited by cold-storage denervation, capsazepine, capsaicin (CGRP depletor), and CGRP(8-37) (CGRP receptor antagonist). Perfusion of adrenergic transmitter metabolites (normetanephrine and 3-methoxydopamine), but not of other metabolites, induced vasodilation, which was not inhibited by capsaicin treatment. Immunohistochemical staining of mesenteric arteries showed dense innervation of CGRP- and TRPV1-immunopositive nerves, with both immunostainings appearing in the same neuron. Mesenteric arteries were densely innervated by neuropeptide Y-immunopositive nerves, which coalesced with CGRP-immunopositive nerves. Scanning and immunoscanning electron microscopic images showed coalescence sites of different perivascular fibers before they intruded into smooth muscles. These results indicate that nicotine initially stimulates adrenergic nerves via nicotinic alpha(3)beta(4)-receptors to release protons and thereby induces CGRPergic nerve-mediated vasodilation via TRPV1.

Protective effect of raloxifene on lung function after acute lung injury in rats

Objective To evalhate the protective effect of oral raloxifene on lung function after acute lung injury (ALI) in rats. Methods Thirty male adult Sprague-Dawley rats were used and divided into three groups: LPS raloxifene hydrochloric acid. group before secondary impact ( Group A, n = 10 ), LPS raloxifene hydrochloric acid group after secondary impact ( Group B, n = 10) and control group ( n = 10). All the rats were injected intraperitoneally with 5 mg/kg LPS. Raloxifene (30 mg/kg) was orally administered one hour before LPS injection and 14 hours after LPS injection in Groups A and B. The con-trol group remained free. All the animals were anesthetized by intraperitoneal injection of pentobarbital so-dium at 40 mg/kg and the femoral artery was cannulated 16 hours after LPS injection to measure the mean arterial pressure (MAP). All the rats received a direct intratracheal injection of hydrochloric acid ( pH = 1.2, 0.5 ml/kg). Before injection of hydrochloric acid and at 0. 5,1.5 and 4 hours after injection of hy-drochloric acid, the blood gas was measured. Fifteen rats ( five from each group) underwent a micro posi-tron emission tomography ( [18F] FDG microPET) scan of the thorax four hours after hydrochloric acid in-stillation. Then, the lung tissue was collected for histopathological examination. Results The Group B showed better pulmonary gas exchange and more stable MAP compared to the control group. The [18F] fluorodeoxyglueose uptake and histological lung injury score were 9. 01 ± 1.58 and 12.6 ± 0.97 respec-tively in Group B, which were higher than 4. 67 ± 1.33 and 9. 01 ± 1.58 respectively in control group (P < 0. 01 ). Conclusions Raloxifene exerts significant protective effect on lung function after ALI. [18F] FDG microPET is a useful method to evaluate the inflammatory reaction during ALI. Key words: Lipopolysaceharides; Respiratory distress syndrome, adult; Raloxifene; Es-trogen receptor modulator

Electrochemistry at cobalt(II)tetrasulfophthalocyanine-multi-walled carbon nanotubes modified glassy carbon electrode: a sensing platform for efficient suppression of ascorbic acid in the presence of epinephrine

Electrochemistry of water-soluble cobalt(II) tetrasulfophthalocyanine (CoTSPc) electrodeposited on glassy carbon nanotube pre-modified with acid-functionalized multi-walled carbon nanotubes (MWCNT) is described. Both charge transfer resistances toward [Fe(CN)6]3−/4− redox probe and electrocatalytic responses toward epinephrine (EP) detection follow the trend: bare GCE < GCE-MWCNT < GCE-CoTSPc < GCE-MWCNT-CoTSPc. EP analysis was then carried out in details using GCE-MWCNT-CoTSPc. The catalytic rate constant value k ch = 2.2 × 107 (mol cm−3)−1 s−1 was obtained from rotating disk electrode experiment. Interestingly, GCE-MWCNT-CoTSPc efficiently suppressed the detection of ascorbic acid (the natural interference of neurotransmitters in physiological conditions) showing good sensitivity (0.132 ± 0.003 A l mol−1), limit of detection (4.517 × 10−7 mol l−1), and quantification (15.056 × 10−7 mol l−1). In addition, GCE-MWCNT-CoTSPc was conveniently used to determine EP in epinephrine hydrochloric acid injection with recovery of 101.1 ± 2.2%.

Efficient Electrocatalytic Detection of Epinephrine at Gold Electrodes Modified with Self‐Assembled Metallo‐Octacarboxyphthalocyanine Complexes

AbstractElectrocatalysis of epinephrine at gold electrode pre‐modified with the self‐assembled monolayer of cysteamine and subsequently integrated with novel metallo‐octacarboxyphthalocyanine (MOCPc where M=Fe, Co and Mn) complexes (Au‐Cys‐MOCPc) was investigated. The electrodes showed response to the presence of epinephrine. The oxidation peak potential (Ep/V vs. Ag|AgCl, sat'd KCl) and charge transfer resistance (Rct (kΩ)) in epinephrine solution depend markedly on the central metal of the phthalocyanine cores: Au‐Cys‐FeOCPc&lt;Au‐Cys‐MnOCPc&lt;Au‐Cys‐CoOCPc. All the electrodes showed first order electrode kinetics in [epinephrine]; the Au‐Cys‐FeOCPc electrode exhibited catalytic rate constant (kch=4.1×107 M−1 s−1) which is higher than that of the Au‐cys‐CoOCPc or Au‐cys‐MnOCPc electrode. Mechanism, recognizing the mediation of the electrocatalytic process by the central M(II)/M(III) redox processes was proposed. Epinephrine electro‐oxidation at the Au‐cys‐FeOCPc electrode was studied in more details for the response characteristics. The diffusion coefficient of epinephrine was evaluated as (2.62±0.23)×10−9 cm2 s−1. It was established that Au‐Cys‐FeOCPc is suitable for sensitive determination of epinephrine in physiological pH (7.40) conditions showing linear concentration range of up to 300 nM, with excellent sensitivity (0.53±0.01 nA nM−1), and very low limits of detection (13.8 nM) and quantification (45.8 nM). The peak separation between ascorbic acid and epinephrine is large enough (190 mV) to permit simultaneous determination of both epinephrine and ascorbic acid in physiological pH 7.4 conditions using the Au‐cys‐FeOCPc electrode. Au‐cys‐FeOCPc electrode was successfully used for the determination of epinephrine in epinephrine hydrochloric acid injection with recovery of ca. 98.4%.

The Unique Mechanism of Analcime Dissolution by Hydrogen Ion Attack

Acidization is the process of injecting acid into porous oil bearing formations to dissolve minerals in the pore space and is a common technique to increase oil production. Analcime is a zeolite which is one of the minerals found in oil reservoirs in the Gulf of Mexico. This mineral is particularly troublesome during the injection of hydrochloric acid during stimulation of the well reservoir because of the precipitation of silicate and analcime dissolution products. To better understand the dissolution/precipitation process, a fundamental investigation of dissolution of analcime was carried out. Experiments establish that silicate precipitates completely from solution during analcime dissolution in hydrochloric acid and that the precipitation does not influence the dissolution kinetics. Comparison of Si and Al initial dissolution rates demonstrates that Al is selectively removed from the zeolite. The selective removal rate parameter is defined as the ratio of the measured Si dissolution rate to the stoichiometric Si dissolution rate. A new concept is introduced of using the selective removal rate parameter to delineate the mechanism of particle dissolution by demonstrating the influence of the Si-to-Al ratio. The mechanism comprises the removal of Si facilitated by the selective removal of Al, leading to the formation of undissolvable silicate particles. Consequently, the unique mechanism of analcime dissolution has general implications pertaining to how microporous materials dissolve.

Corrosive injury from arterial injection of hydrochloric acid

This report presents a case of hydrochloric acid injection in the inguinal area in a suicide attempt, resulting in total occlusion of the external iliac artery, requiring disarticulation of the hip. To the authors' best knowledge, it has not been previously reported in the English medical literature. The accelerated destructive activity of these irritant chemicals and deep tissue damages are emphasized. Early and aggressive debridement with copious saline irrigation and circumspect monitoring are recommended.

All Solid State Hydrogen Ion Selective Electrode Based on a Tribenzylamine Neutral Carrier in a Poly(vinyl chloride) Membrane with a Poly(aniline) Solid Contact

Hydrogen ion selective solid contact electrode based on tribenzylamine have shown the best Nernstian slope, selectivity and the widest response range in Tris buffered pH sample solutions. Their linear dynamic range was pH 2.48–11.21 and Nernstian slope showed 55.1 mV/pH (at 20±0.2 °C). When it was directly applied to human whole blood (in pH range 6.0–8.5), we could get the same satisfying results. This electrode continuously contacted Tris 7.47 buffered solutions, human whole blood and hydrofluoric acid solutions for one month without any loss of performance. Especially, hydrofluoric acid did not influence the surface of this electrode, thus this electrode was maintained without showing any changes in potentials after used in hydrofluoric acid solution. The standard deviation in the e.m.f. differences determined was 1.0 mV (N=10) at Tris buffer solution of pH 6.5 and 0.5 mV at Tris buffer solution of pH 8.5. The 90 % response time of the electrodes obtained by injection of hydrochloric acid into Tris buffer sample solution was less than 8 s.

Alternative Stimulation Fluids and Their Impact on Carbonate Acidizing

Abstract Acidizing treatments are commonly used to remove near-wellbore damage and create artificial flow channels in carbonate formations. Matrix acidizing treatments are most useful when fracture acidizing is undesirable, such as when a shale break or other natural boundary must be maintained to prevent water or gas production1 or where fracture acidizing is ineffective, such as in soft chalk formations.2 Unfortunately, matrix treatments often require low injection rates to prevent fracturing the formation rock. These treatments may also be required in heterogeneous formations with zones of low conductivity (which need stimulation the most) that accept acid at low rates. It is at these low injection rates that the problem of rapid acid spending severely limits the acid penetration distance. The injection of hydrochloric acid (HCl) into carbonate formations at low rates results in face dissolution, or complete dissolution of the carbonate matrix near the wellbore. This face dissolution consumes large volumes of acid and provides negligible increases in the conductivity of the formation. Various acid systems have been used to reduce the limitations of rapid acid spending at low injection rates. A few of the acids include: weak acids, such as acetic and formic acid, which have relatively low H+ concentrations and therefore react with carbonates at a slower rate than HCl3,4; chemically retarded acids, such as oil external microemulsion systems containing HCl, that retard acid diffusion to the carbonate surface and thus allow deeper penetration of live acid2; and foamed acids (nitrogen gas and aqueous HCl) that prevent acid from spending outside the primary dissolution channel, thereby promoting the growth of wormholes.5 Although retarded and foamed acid systems can stimulate carbonate formations at lower injection rates, strong acids such as HCl induce the precipitation of asphaltic sludge from crude oil. This sludge can plug the formation and restrict production after an acidizing treatment. When ferric ions are present, this problem is even more severe.6 Thus, adequate corrosion protection becomes more essential. Acetic acid (HAc), an iron chelating agent, does not reduce sludging tendencies in the presence of ferric and ferrous iron.6 A variety of acid additives (antisludging agents, corrosion inhibitors, and iron-reducing agents) have been used to prevent the sludging problem. However, their effectiveness is limited by the need to obtain a compatible combination of additives and a lack of understanding of the complex chemistries involved in the precipitation reactions. These limitations demonstrate the need for an alternative stimulation fluid that combines the ability to stimulate at low injection rates with fluid properties that are not conducive to asphaltic sludge precipitation or corrosion problems.

Stimulation of pulmonary C fibres by lactic acid in rats: contributions of H+ and lactate ions.

1. The contributions of H+ and lactate ions to the stimulation of single pulmonary C fibres by lactic acid were examined in anaesthetized and artificially ventilated rats. 2. Lactic acid injected into the right atrium caused a transient decrease in arterial blood pH (pHa) and a short but intense burst of afferent activities in pulmonary C fibres, whereas sodium lactate had no effect. The fibre activity usually reached a peak within 1-1.5 s, with an onset latency of < 1 s, and returned to the baseline in 5 s. 3. The injection of hydrochloric acid at the same pH as that of lactic acid did not significantly decrease pHa, nor did it stimulate any C fibres studied. 4. Formic acid has a pKa value (the negative logarithm of the dissociation constant) almost identical to that of lactic acid; thus, its injection decreased pHa to the same degree as did the injection of lactic acid. However, the response of C fibres to lactic acid was 134% stronger than that to formic acid. 5. We conclude that H+ is primarily responsible for the activation of pulmonary C fibres by lactic acid, probably through a direct effect of H+ on these afferent endings. The lactate ion, by itself, does not activate C fibres, but it seems to potentiate the stimulatory effect of H+ on these afferents.

Participation of capsaicin-sensitive afferent neurons in gastric motor inhibition caused by laparotomy and intraperitoneal acid

Stimulation of somatic or visceral nociceptors causes changes in gastrointestinal motor activity and blood pressure. The present study examined the possible participation of capsaicin-sensitive afferent and noradrenergic efferent neurons in the blood pressure and gastric motor responses to laparotomy and intraperitoneal injection of capsaicin or hydrochloric acid in the rat. Gastric motor activity was measured by recording the intragastric pressure of phenobarbital-anaesthetized rats via an oesophageal catheter. Laparotomy as well as intraperitoneal injection of capsaicin (33 and 330 μM) or hydrochloric acid (30 mM) caused a transient reduction of gastric motor activity stimulated by intravenous infusion of bombesin (200 pmol/min) and a brief fall of blood pressure (depressor effect). The depressor effect of laparotomy was followed by prolonged hypertension. Defunctionalization of capsaicin-sensitive afferent neurons by systemic pretreatment of rats with capsaicin (0.4 mmol/kg) prevented the depressor effect and gastric motor inhibition elicited by laparotomy, intraperitoneal capsaicin (33 μM) or intraperitoneal hydrochloric acid (30 mM). However, the effects of 330 μM capsaicin on blood pressure and gastric motility were only partially reduced by capsaicin pretreatment. Blockade of noradrenergic sympathetic neurons by pretreating rats with guanethidine (0.225 mmol/kg) prevented the gastric motor inhibition and depressor effects of laparotomy and intraperitoneal injection of hydrochloric acid (30 mM). The inhibition of gastric motility caused by capsaicin (33 and 330 μM) was only partially reduced by guanethidine pretreatment. The secondary hypertension following the depressor effect of intraperitoneal capsaicin or hydrochloric acid was enhanced in guanethidine-pretreated rats whereas the prolonged hypertension induced by laparotomy was left unchanged. These observations indicate that laparotomy and intraperitoneal injection of algesic chemicals inhibit gastric motor activity and elicit a depressor effect by a neural reflex. The afferent limb of the reflex is constituted by capsaicin-sensitive afferent neurons, which comprise unmyelinated primary afferents connected to chemoceptors and polymodal nociceptors, whilst the efferent reflex limb involves noradrenergic sympathetic neurons. This neural wiring may have a bearing on pathological inhibition of gastrointestinal motility.

Geochemical modeling of two‐phase flow with interphase mass transfer

AbstractInjecting an acidic aqueous solution into a carbonate‐rich permeable medium can cause the formation of a mobile gas phase through mineral dissolution. The flowing gas can cause significant changes in mineral identities through interaction with the initially present mineral and aqueous species. We have developed a solution to such transport problems based on a finite difference implicit‐pressure/explicit‐saturation formulation for two‐phase flow, using the local equilibrium assumption as calculated with the Villars‐Cruise‐Smith stoichiometric chemical equilibrium algorithm.We illustrate the changes that occur to a calcite/iron (II) hydroxide medium upon injection of hydrochloric acid and the stripping of hydrogen sulfide gas from carbon dioxide gas injected into a siderite‐rich medium. The examples demonstrate that the formation and/or presence of a gas phase can alter resident minerals and that minerals can remove impurities from a gas phase.

High-pressure Acid Injection

This report represents a case of high-pressure hydrochloric acid injection of the shoulder girdle, with the resultant need for aggressive debridement in the form of extended forequarter amputation. The accelerated destructive activity of such reducing agents and the need for neutralization or removal of these agents is emphasized. Debridement, copious saline irrigation, and careful periodic monitoring are recommended.