Predicting full-thickness necrosis in adult acute corrosive ingestion injuries in a sub-Saharan African setting

BACKGROUND Corrosive ingestion remains an important global pathology with high morbidity and mortality.Data on the acute management of adult corrosive injuries from sub-Saharan Africa is scarce,with international investigative algorithms,relying heavily on computed tomography(CT),having limited availability in this setting.AIM To investigate the corrosive injury spectrum in a low-resource setting and the applicability of parameters for predicting full-thickness(FT)necrosis and mortality.METHODS A retrospective analysis of a prospective corrosive injury registry(March 1,2017–October 31,2023)was performed to include all adult patients with acute corrosive ingestion managed at a single,academic referral centre in Cape Town,South Africa.Patient demographics,corrosive ingestion details,initial investigations,management,and short-term outcomes were described using descriptive statistics while multivariate analysis with receiver operator characteristic area under the curve graphs(ROC AUC)were used to identify factors predictive of FT necrosis and 30-day mortality.RESULTS One-hundred patients were included,with a mean age of 32 years(SD:11.2 years)and a male predominance(65.0%).The majority(73.0%)were intentional suicide attempts.Endoscopy on admission was the most frequent initial investigation performed(95 patients),while only 17 were assessed with CT.Seventeen patients had full thickness necrosis at surgery,of which eleven underwent emergency resection and six were palliated.Thirty-day morbidity and mortality were 27.0%and 14.0%,respectively.Patients with full thickness necrosis and those with an established perforation had a 30-day mortality of 58.8%and 91.0%,respectively.Full thickness necrosis was associated with a cumulative 2-year survival of only 17.6%.Multivariate analyses with ROC AUC showed admission endoscopy findings,CT findings,and blood gas findings(pH,base excess,lactate),to all have significant predictive value for full thickness necrosis,with endoscopy proving to have the best predictive value(AUC 0.850).CT and endoscopy findings were the only factors predictive of early mortality,with CT performing better than endoscopy(AUC 0.798 vs 0.759).CONCLUSION Intentional corrosive injuries result in devastating morbidity and mortality.Locally,early endoscopy remains the mainstay of severity assessment,but referral for CT imaging should be considered especially when blood gas findings are abnormal.

Development of anti-corrosive coating on AZ31 Mg alloy modified by MOF/LDH/PEO hybrids

The self-assembly of hybrid inorganic-organic materials on stationary platforms plays a critical role in improving their structural stability and wide usability.In this work,a novel two-step hydrothermal approach is proposed for synthesizing stable and advanced hybrid coatings on metal-oxide platforms through the surface modification of layered double hydroxide(LDH)films using novel metal-organic frameworks(MOFs).Initially,Mg-Al LDH nanocontainers,grown on a magnesium oxide layer produced through plasma electrolytic oxidation(PEO)of AZ31 Mg alloy substrate,were intercalated with cobalt via an oxidation route,providing the metallic coordination center for the MOF formation.In the subsequent step,a pioneering technique is introduced,utilizing tryptophan as the organic linker for the first time at a pH of 10.The self-assembly of cobalt-tryptophan complex,driven by the strong bonding between electrophilic sites of monomers and nucleophilic sites,facilitated the formation of a MOF network having a cloud-like structure on the surface of MgAl LDH's film.The resulting MOF-LDH encapsulation containers demonstrate exceptional electrochemical stability when exposed to a 3.5 wt.%NaCl solution,surpassing the performance of PEO and pure LDH coatings.This enhanced stability is attributed to the development of a dense top layer and a stable composition within the self-assembled MOF,effectively sealing flaws and preventing the infiltration of corrosive ions into the underlying metallic substrate.The formation mechanism of MOFs on LDH galleries is investigated using density functional theory calculations.

Improving corrosive wear resistance of Mg-Zn-Y-Zr alloys through heat treatment

The wear behavior of an as-received Mg-Zn-Y-Zr alloy before and after a facile heat treatment was investigated under sliding in air and 0.5 wt.%NaCl solution.Results revealed that the wear resistance of the alloy was remarkably enhanced after the heat treatment,irrespective of testing condition.The wear mechanism was predominantly abrasive wear accompanied by oxidation under the dry sliding condition,while corrosive wear was dominant under sliding in the NaCl solution.The superior corrosive wear resistance was attributed to the homogenous distribution of fine I-phase precipitates in the alloy by the heat treatment,leading to a reduction in wear,corrosion as well as wear-corrosion synergy.The wear-accelerated corrosion rate was remarkably alleviated after the heat treatment.

A numerical case study on the long-term seismic assessment of reinforced concrete tunnels in corrosive environments

The paper investigates the long-term seismic behaviour of an underground reinforced concrete(RC)metro tunnel in Santiago,Chile,considering the combined effects of chloride-induced corrosion and cumulative,low-amplitude seismic shaking on the structure’s performance.The soil-tunnel response is evaluated with the aid of transient,nonlinear finite element analysis using a two-dimensional(2D)plane strain numerical model that adopts advanced nonlinear models for the simulation of soil and concrete plasticity and the dynamic stiffness behaviour.The effects of corrosion deterioration are demonstrated in terms of time-dependent loss of rebar area and cover concrete stiffness and strength.The study illustrates the influence of ageing and repeated seismic shaking on lining deformation,crack development,and the modal characteristics of the intact and degrading systems.The results indicate that multiple lowamplitude events drive the non-degrading RC tunnel beyond its elastic regime without significant structural response consequences.A noticeable impact of corrosion deterioration on the structure’s seismic performance is revealed,increasing with the number and intensity of earthquake events.Two different tunnel embedment depths are comparatively assessed.The analyses demonstrate larger coseismic section convergence in the case of the deeper tunnel,yet a less pronounced effect of ageing and successive seismic loading compared to the shallow section,which is evident in the RC lining cracks at the end of shaking.

Experimental Study on Cemented Soil in Sulfate Radical Corrosive solution

The cemented soil is a widely used method to stabilize the weak soil.It would be working in polluted environment,and be influenced by environmental pollution such as acid rain,seawater invasion or industrial pollution,which may lead to deterioration of the structure.In order to simulate and study the erosion effect process including as the changes of corrosive degree of surface,compression strength of cemented soil samples and SO_(4)^(2-)concentration of corrosive solutions,a series of tests are conducted on the cemented soil blocks cured in different concentrations of MgSO_(4),H_(2)SO_(4)and Na_(2)SO_(4)solutions.The test results show that the corrosive degree of the sample surface increases while the compression strength decreases with the increase of the corrosive solution concentration at the same erosion time,and that the corrosive degree increases with the corrosive time.The influence of inorganic compound solutions on the cemented soil follows the order of Na_(2)SO_(4)>MgSO_(4)>H_(2)SO_(4).By analyzing the mechanism,the corrosive type of H_(2)SO_(4)and MgSO_(4)solutions to cemented soil is a composite type of resolving and crystallizing combination,and Na_(2)SO_(4)solution to cemented soil is a composite type of dissolving and crystallizing combination.

CORRELATION AMONG CORROSIVE FACTORS OF SOIL

In this paper, through the data treatment of correlation coefficients and the clustering technique of pattern recognition, both the matrix of correlation coefficients and the pedigree of factor clusters show that some factors affecting soil corrosivity are interrelated closely, and some independent relatively. The data analytical method used in this paper has certain assistance to the selection of major soil factors during the prediction and evaluation of soil corrosivity.

Aorto-oesophageal fistula after corrosive ingestion:A case report

BACKGROUND Aorto-oesophageal fistula(AOF)are uncommon and exceedingly rare after corrosive ingestion.The authors report a case of AOF after corrosive ingestion that survived.A comprehensive literature review was performed to identify all cases of AOF after corrosive ingestion to determine the incidence of this condition,how it is best managed and what the outcomes are.CASE SUMMARY A previously healthy 30-year-old male,presented with a corrosive oesophageal injury after drain cleaner ingestion.He did not require acute surgical resection,but developed long-segment oesophageal stricturing,which was initially managed with cautious dilatation and later stenting.An AOF was suspected at endoscopy performed two months after the ingestion,when the patient represented with massive upper gastrointestinal bleeding.The fistula was confirmed on computerised tomographic angiography.The initial bleeding at endoscopy was temporised by oesophageal stenting;a second stent was placed when bleeding recurred later the same day.The stenting successfully achieved temporary bleeding control,but resulted in sudden respiratory distress,which was found to be due to left main bronchus compression caused by the overlapping oesophageal stents.Definitive bleeding control was achieved by endovascular aortic stent-grafting.A retrosternal gastroplasty was subsequently performed to achieve gastrointestinal diversion to reduce the risk of stent-graft sepsis.He was subsequently successfully discharged and remains well one year post injury.CONCLUSION AOF after corrosive ingestion is exceedingly rare,with a very high mortality.Most occur weeks to months after the initial corrosive ingestion.Conservative management is ill-advised.

Dry Friction and Wear Characteristics of Impregnated Graphite in a Corrosive Environment

Tribological properties of impregnated graphite are greatly influenced by preparation technology and working conditions and it’s highly susceptible to corrosion environmental impacts,but the experimental research about it are few.In this paper,three kinds of impregnated graphite samples are prepared with different degree of graphitization,the tribological properties of these samples in the dry friction environment and in a corrosive environment are analyzed and contrasted.The tribo-test results show that the friction coefficient of samples is reduced and the amount of wear of samples increase when the graphitization degree of samples increases in dry friction condition.While in a corrosive environment（samples are soaked N2O4）,the friction coefficient and amount of wear are changed little if the graphitization degree of samples are low.If the degree of graphitization increase,the friction coefficient and amount of wear of samples increase too,the amount of wear is 2 to 3 times as the samples tested in the non-corrosive environment under pv value of 30MPa？m/s.The impregnated graphite,which friction coefficient is stable and graphitization degree is in mid level,such#2,is more appropriate to have a work in the corrosion conditions.In this paper,preparation and tribological properties especially in corrosive environment of the impregnated graphite is studied,the research conclusion can provide an experimental and theoretical basis for the selection and process improvement of graphite materials,and also provide some important design parameters for contact seal works in a corrosive environment.

Development and evaluation of corrosion resistant coating for expandable rock bolt against highly corrosive ground conditions

Expandable rock bolts are widely used in hard rock mines as an efficient ground control product.However, capacity and service life can be significantly reduced if the metallic body is subjected to corrosion.In some hard rock mines in the U.S., highly corrosive ground conditions exist, and it has been reported that inflatable rock bolts have corroded within a few months after installation.To provide mining industry a cost-effective inflatable bolt and combat the corrosion issues, Jennmar Corporation, Inc.,and its subsidiary Keystone Mining Services, LLC(KMS), analyzed corroded bolt samples, identified root causes, evaluated properties of various coating materials, and developed a new inflatable rock bolt,Python M3^(TM), that is protected with an innovative PyFlexU2^(TM)coating.The new generation Python M3^(TM) features improved steel chemistry for reliable performance, modified profile for better inflation, and surface preparation and coating application.The PyFlexU2^(TM)is impervious to liquid and air, durable, and UV resistant.With a flexible, adhesive, and highly corrosion-resistant undercoating, and a very hard sacrificial surface coating, the PyFlexU2^(TM)coating system provides the Python M3^(TM)superior protection against chemical corrosion and physical scratch damage.The under-coating has exceptional flexibility and adhesion to prevent coating micro-cracks or fractures after bolt inflation and possesses excellent corrosion resistance to acids(pH < 3), alkalis(p H > 11), fuels, and salt solvents.The corrosion and scratch resistant PyFlexU2^(TM)coating offers very effective bolt protection for extra longevity in highly corrosive environments.The Python M3^(TM)coated with PyFlexU2^(TM)has been tested in the most challenging conditions,including laboratory corrosion tests in extreme acidic and basic solvents, rock slurry, and borehole scratch insertion tests.With demonstrated corrosion and scratch resistance, the product has been greatly welcomed by hard rock mines in the West and is currently installed in large scale.This paper identifies the root causes of the bolt corrosion, discusses the analysis process, and details laboratory and underground tests carried out on the Python M3^(TM)coated with PyFlexU2^(TM).The Python M3^(TM)and PyFlexU2^(TM) are subjects covered by pending U.S.Patent Applications assigned to FCI Holdings Delaware, LLC.

Analysis of cultivable aerobic bacterial community composition and screening for facultative sulfate-reducing bacteria in marine corrosive steel

Anaerobic, aerobic, and facultative bacteria are all present in corrosive environments. However, as previous studies to address corrosion in the marine environment have largely focused on anaerobic bacteria, limited attention has been paid to the composition and function of aerobic and facultative bacteria in this process. For analysis in this study, ten samples were collected from rust layers on steel plates that had been immersed in seawater for diff erent periods (i.e., six months and eight years) at Sanya and Xiamen, China. The cultivable aerobic bacterial community structure as well as the number of sulfate-reducing bacteria (SRB) were analyzed in both cases, while the proportion of facultative SRB among the isolated aerobic bacteria in each sample was also evaluated using a novel approach. Bacterial abundance results show that the proportions are related to sea location and immersion time;abundances of culturable aerobic bacteria (CAB) and SRB from Sanya were greater in most corrosion samples than those from Xiamen, and abundances of both bacterial groups were greater in samples immersed for six months than for eight years. A total of 213 isolates were obtained from all samples in terms of CAB community composition, and a phylogenetic analysis revealed that the taxa comprised four phyla and 31 genera. Bacterial species composition is related to marine location;the results show that Firmicutes and Proteobacteria were the dominant phyla, accounting for 98.13% of the total, while Bacillus and Vibrio were the dominant genera, accounting for 53.06% of the total. An additional sixfacultative SRB strains were also screened from the isolates obtained and were found to encompass the genus Vibrio (four strains), Staphylococcus (one strain), and Photobacterium (one strain). It is noteworthy that mentions of Photobacterium species have so far been absent from the literature, both in terms of its membership of the SRB group and its relationship to corrosion.

Effect of SiC content on dry sliding wear, corrosion and corrosive wear of Al/SiC nanocomposites

The corrosion, corrosive wear and dry sliding wear of nanocomposites, are extremely complicated and involve various chemical, physical anbd mechanical factors. The aim of this work is to investigate the effects of nanosized SiC content on the hardness, dry sliding wear, corrosion and corrosive wear of Al/SiC nanocomposites synthesized by mechanical milling cold pressing and hot extrusion. The corrosion resistance of these composites in 3%NaCl solution was investigated by electrochemical polarization testing and their dry sliding as well as corrosive wear resistance in the same solution was evaluated using a pin-on-disc tester. The microstructures of the samples and their worn surfaces were examined using scanning electron microscopy. It was shown that the dry sliding wear and corrosion resistance of these nanocomposites were improved with the increase of SiC content. It was concluded that due to the lubrication effect of the solution, both the friction coefficient and frictional heat that might soften the material were reduced. In addition, the improved strength of the nanocomposites combined with their better corrosion resistance contributed to their increased corrosive wear resistance, compared with the base alloy. The prominent wear mechanism in the unreinforced alloy was adhesive wear, in the Al/SiC nanocomposites, the wear mechanism changed to abrasive.

Colon Interposition for Corrosive Esophageal Stricture: Single Institution Experience with 119 Cases

The colon is an alternative graft organ for esophageal reconstruction.The present study reviewed our experience with the colon interposition for esophageal replacement following corrosive ingestion,to evaluate the outcomes of colon interposition based on our surgical experience. The clinical data of 119 patients who underwent colon interposition for esophageal replacement from January 2005 to March 2017 were retrospectively analyzed. The routes of the colon interposition were retrosternal in 119 (100%). The median operative time was 390 min (range: 290-610 min) and the median blood loss was 615 mL (range:270-2500 mL). Of these 119 patients, the cervical anastomosis was performed at the hypopharynx (n=20,16.8%), the larynx (n=3,2.5%), and the cervical esophagus (n=96, 80.7%). Five patients experienced cervical anastomotic leakage (4 cases for esophagus-colon, and one for hypopharynx-colon).One patient experienced wound infection of the abdominal wall. Three patients had injury of recurrent laryngeal nerve and hoarseness. Three patients had stress ulcer with bleeding and treated with octreotide. Two patients suffered from incomplete intestinal obstruction. The postoperative follow-up was made for 12 months in all patients and all of them were alive. In conclusion, The colon is well-suited for esophageal reconstruction. The selection of the colon graft should be flexible and be based on the inspection of blood supply and the length needed. We must therefore make every effort to reduce the number of postoperative complications, and improve the quality of life for patients.

Corrosive-wear and Electrochemical Performance of Laser Thermal Sprayed Co30Cr8W1.6C3Ni1.4Si Coating on Ti6Al4V Alloy

Co30Cr8W1.6C3Ni1.4Si coatings were fabricated on Ti6Al4V alloy using a laser thermal spraying(LTS).The surface and cross-section morphologies,phases and bonding strength of obtained coatings were investigated using scanning electronic microscopy(SEM),X-ray diffraction(XRD),and scratch test,respectively.The effects of laser power on the coefficients of friction(COFs)and corrosive-wear behaviors of Co30Cr8W1.6C3Ni1.4Si coatings were investigated using a wear tester in 3.5%NaCl solution,and the electrochemical corrosion performance was analyzed using an electrochemical workstation.The experimental results show that the Co30Cr8W1.6C3Ni1.4Si coating is bonded with the substrate in the metallurgical form,and the bonding strengths of Co30Cr8W1.6C3Ni1.4Si coatings fabricated at the laser power of 1000,1200,and 1400 W are 76.5,56.5,and 55.6 N,respectively.The average COFs of Co30Cr8W1.6C3Ni1.4Si coatings fabricated at the laser power of 1000,1200,and 1400 W are 0.769,0.893,and 0.941,respectively;and the corresponding wear rates are 0.267×105,0.3178×105,and 0.325×105μm3/Nm,respectively,which increases with the increase of laser power,the wear mechanism is primarily abrasive wear.The corrosion potential of Co30Cr8W1.6C3Ni1.4Si coatings fabricated at the laser power of 1000,1200,and 1400 W is-0.05,-0.25,and-0.31 V,respectively,higher than-0.45 V of substrate which enhances the electrochemical corrosion resistance of substrate.

Effect of molybdenum on the microstructure and corrosive wear resistance of laser clad Ni-based coatings

Five kinds of Ni-based coatings with 0 wt% , 2. 5 wt% , 5.0 wt% , 7.5 wt% and 10. 0 wt% molybdenum were prepared on 45CrNi steel plates by using laser cladding technique. The effect of Mo on the microstructure of Ni-based coatings was investigated by using scanning electron microscopy. The corrosive wear resistance and the corrosion resistance of five coatings were tested. The results show that the corrosive wear resistance of the coating with 5.0 wt% Mo is better than those of other coatings. During the corrosive wear process, the corrosion and wear effects are combined. The corrosive wear resistance is closely related to the microstructure of the coating.

An uncommon cause of corrosive esophageal injury

We present an unusual case of corrosive esophageal injury following liquid glue ingestion. The endoscopic f indings were tissue sloughing and blackened appearance of the esophagogastric junction,due to caustic esophageal injuries following ingestion of glue containing toluene.

Development of anti-corrosive coating on AZ31 Mg alloy subjected to plasma electrolytic oxidation at sub-zero temperature

Plasma electrolytic oxidation(PEO)is a promising surface treatment to generate adherent and thick anti-corrosive coating on light-weight metals(Al,Mg,Ti,etc.)using an eco-friendly alkaline electrolyte.High energy plasma,however,inevitably generates porous structures that limit their practical performance.The present study proposes a straight-forward simple method by utilizing sub-zero electrolyte(268 K)to alter the plasma characteristics during formation of the protective coating on AZ31 Mg alloy via PEO with a comparison to the electrolyte at room temperature(298 K).In refrigerated electrolyte,the formation of micro-defects is suppressed relatively at the expense of low coating growth,which is measured to be twice lower than that at 298 K due to the temperature-dependent soft plasma discharges contributing to the development of the present coating.As a consequence,corrosion resistance of the sample processed at 268 K is superior to that of 298K,implying that the effect of coating thickness is less dominant than that of compactness.This phenomenon is interpreted in relation to the ionic movement and oxide solidification controlled by soft plasma discharges arising from the temperature gradient between electrolyte and surface of the substrate during PEO.

Intercalation and Stability of Layered Semiconductive Material in Corrosive Environment

The intercalation of 4-methyl pyridine （4-picoline） into layered semiconductive material （MnPS3） and the stability of the resulting materials in corrosive environments （water, HCI and open atmosphere） were investigated. Powder X-ray diffraction （XRD） indicated that the presence of water and hydrochloric acid greatly influenced the existing form of intercalation and its orientation in the interlayer of the host. Atmospheric environment （open air） affected the guest orientation in the interlayer of the host material. Phase transformation occurred and the material was stable. The intercalated compounds could be indexed in the trigonal unit cell. The XRD patterns exhibited sharp hkl reflections of the intercalated compounds, which formed in water and HCI, confirming that the materials were well crystalline and stable in corrosive environments.

Effect of Corrosive Solutions on C-S-H Microstructure in Portland Cement Paste with Fly Ash

By means of ^（29）Si and ^（27）Al magic angle spinning nuclear magnetic resonance（MAS NMR） combined with deconvolution technique, X-ray diffraction（XRD）, scanning electron microscopy（SEM） as well as energy dispersive X-ray system（EDX）, the effect of 5 wt% corrosive solutions（ viz. 5 wt% Na_2SO_4, MgSO_4, Na_2SO_^（4＋）Na Cl and Na_2SO_^（4＋）Na Cl＋Na_2CO_3） on C-S-H microstructure in portland cement containing 30 wt% fly ash was investigated.The results show that, in MgSO_4 solution, Mg2＋ promotes the decalcification of C-S-H by SO_4^（2-）,increasing silicate tetrahedra polymerization and mean chain length（MCL） of C-S-H. However, the substituting degree of Al^（3＋） for Si^（4＋）（Al[4]/Si） in the paste does not change evidently. Effect of Na_2SO_4 solution on C-S-H is not significantly influenced by Na Cl solution, while the MCL and Al[4]/Si of C-S-H in fly ashcement paste slightly change. However, the decalcification of C-S-H by SO_4^（2-） and CO_3^（2-） attack, as well as the activation of fly ash by SO_4^（2-） attack will increase the MCL and Al[4]/Si, which are both higher than that under Na_2SO_4 corrosion, MgSO_4 or Na_2SO_4 ＋Na Cl coordination corrosion.

Corrosive electrochemistry of jamesonite by cyclic voltammetry

The corrosive electrochemistry of jamesonite was studied by cyclic voltammetry. Every peak in voltammograms was identified through thermodynamic calculation. The results show an irreversible electrode process by the strong adsorption of oxidation elemental sulfur on jamesonite. A deficient-metal and sulfur-rich compound is formed under the potential of 80 mV at pH 6.86. The passive action by elemental sulfur occurs from 80 to 470 mV and S2O2-3, SO2-4 are produced at potential over 470 mV. The anodic peak producing SO2-4 is inhibited due to the deposition of PbSO4 at higher potential in Na2SO4 solution. The corrosive action of jamesonite becomes strong and the redox characterization similar to PbS, FeS and Sb2S3 appears at pH 9.18.

Corrosive upper gastrointestinal strictures in children:Difficulties and dilemmas

Children constitute 80%of all corrosive ingestion cases.The majority of this burden is contributed by developing countries.Accidental ingestion is common in younger children(<5 years)while suicidal ingestion is more common in adolescents.The severity of injury depends on nature of corrosive(alkali or acid),pH,amount of ingestion and site of exposure.There are multiple doubts and dilemmas which exist in management of both acute ingestion and chronic complications.Acute ingestion leads to skin,respiratory tract or upper gastrointestinal damage which may range from trivial to life threatening complications.Esophagogastroduodenoscopy is an important early investigation to decide for further course of management.The use of steroids for prevention of stricture is a debatable issue.Upper gastrointestinal stricture is a common longterm sequelae of severe corrosive injury which usually develops after three weeks of ingestion.The cornerstone of management of esophageal strictures is endoscopic bougie or balloon dilatations.In case of resistant strictures,newer adjunctive therapies like intralesional steroids,mitomycin and stents can be utilized along with endoscopic dilatation.Surgery is the final resort for strictures resistant to endoscopic dilatations and adjunctive therapies.There is no consensus on best esophageal replacement conduit.Pyloric strictures require balloon dilatation,failure of which requires surgery.Patients with post-corrosive strictures should be kept in long term follow-up due to significantly increased risk of carcinoma.Despite all the endoscopic and surgical options available,management of corrosive stricture in children is a daunting task due to high chances of recurrence,perforation and complications related to poor nutrition and surgery.