Engineered Electroactive Solutions for Electrochemical Detection of Tuberculosis-Associated Volatile Organic Biomarkers.

Rapid screening of tuberculosis by evaluation of associated volatile organic biomarkers in breath is a promising technology that is significantly faster and more convenient than traditional sputum culture tests. Methyl nicotinate (MN) and methyl p-anisate (MPA) have been isolated as potential biomarkers for mycobacterium tuberculosis and have been found in the breath of patients with active pulmonary tuberculosis. A novel approach to detection of these biomarkers in liquid droplets (e.g. from breath condensate) using inexpensive screen-printed electrodes is presented. Previous modelling studies suggest that these biomarkers complex with certain transition metals of particular valence state. This interaction can be exploited by mixing the biomarker sample into an electroactive solution (EAS) containing the functional metal ion and observing the change electrochemically. The study focuses on low biomarker concentrations, determined to be clinically relevant based on preliminary GC-MS studies of the levels found in patient breath. It was found that both the cyclic voltammogram and square wave voltammogram of copper(II) change significantly when as little as 0.1 mM MN is added to the solution, with analysis times of less than 2 min. Copper(II) exhibits three separate peaks during square wave voltammetry. The location and area of each peak are affected differently as the concentration of MN increases, suggesting a reaction with specific oxidation states of the metal. In this way, a "fingerprint" method can be used to identify biomarkers once their known interaction is established.

Developments in Micro- and Nanotechnology for Foodborne Pathogen Detection.

In response to the potential hazards associated with the globalization of the food industry, research has been focused on the development of new sensing techniques to provide the means of contamination detection at any stage in the food supply chain. The demand for on-site detection is growing as pre-emptive sensing of pathogens could eliminate foodborne-related outbreaks and associated healthcare costs. Reduction in food waste is also a driver for point-of-use (POU) sensing, from both an economic and environmental standpoint. The following review discusses the latest advancements in platforms that have the greatest potential for inexpensive, real-time detection, and identification of foodborne pathogens. Specific focus has been placed on the development techniques, which utilize micro- and nanoscale technology. Sample preparation-free techniques are also discussed, as the growing demand to enable POU sensing at any stage in the food supply chain will be a major driver toward the advancements of these nondestructive methods.

A Comprehensive Review on Finite Element Analysis of Laser Shock Peening.

Laser shock peening (LSP) is a formidable cold working surface treatment that provides high-energy precision to enhance the mechanical properties of materials. This paper delves into the intricacies of the LSP process, offering insights into its methodology and the simulation thereof through the finite element method. This review critically examines various points, such as laser energy, overlapping of shots, effect of LSP on residual stress, effect of LSP on grain refinement, and algorithms for simulation extrapolated from finite element analyses conducted by researchers, shedding light on the nuanced considerations integral to this technique. As the significance of LSP continues to grow, the collective findings underscore its potential as a transformative technology for fortifying materials against mechanical stress and improving their overall performance and longevity. The discourse encapsulates the evolving landscape of the LSP, emphasizing the pivotal role played by finite element analysis in advancing our understanding and application of this innovative surface treatment.

Polyaniline/Titania Nanotube-Based Biosensor Strip for Sensitive and Specific Electrochemical Detection of SARS-CoV-2.

This study showcases the creation of a biosensor strip designed for the rapid, precise, and highly sensitive electrochemical detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). These biosensor strips were crafted by affixing a monoclonal antibody (mAb) specific to SARS-CoV-2 onto the surface of a commercially screen-printed carbon electrode (SPCE) modified with polyaniline-titania nanotubes (PANi-TNT). The transportable sensing device was constructed by pairing the mAb functionalized strip with a portable potentiostat wirelessly connected to either a Windows or Android device. Fast and specific conjugation between spike protein of SARS-CoV-2 and immobilized anti-SARS-CoV-2 triggered a change in the charge and electron mobility in the biosensing layer of the strip to produce detectable current during chronoamperometric scanning in the presence of a phosphate buffer solution (PBS). The excellent sensitivity and specificity of the sensor toward SARS-CoV-2 were detected as analytical analysis demonstrated linearity in the range of 80 to 200 copies/µL with a limit of detection of 25.59 copies/µL from the dose-response and standard fitted curve. Through experimental validation, the sensor strip's ability to specifically detect SARS-CoV-2 was established, distinguishing it from human coronavirus-OC43 (HCoV-OC43), HCoV-NL63, HCoV-229E, and adenovirus. The results from these tests indicate that these strips possess the potential for the future creation of dependable and easily transportable point-of-care diagnostic devices, enabling swift, sensitive, and precise detection of SARS-CoV-2 in the saliva or nasopharyngeal fluid of individuals infected with the virus.

Manufacturing Bulk Nanocrystalline Al-3Mg Components Using Cryomilling and Spark Plasma Sintering.

In the current study, pure aluminum (Al) powders were cryomilled with and without 3 wt.% pure magnesium (Mg) dopant for varying durations followed by spark plasma sintering (SPS) of powders to prepare bulk components with superior mechanical properties. The crystallite sizes were determined for powders and the bulk components by analyzing the X-ray diffraction (XRD) spectrum. The calculations indicated a reduction in crystallite size with the increase in the cryomilling duration. The results also showed a more significant decrease in the crystallite sizes for Al-3Mg samples than that of pure Al. The changes in the surface morphology of powders were characterized using scanning electron microscopy (SEM). The elemental mapping analysis at nanoscale was carried out using Energy-dispersive X-ray spectroscopy (EDX) in Scanning transmission electron microscopy (STEM). The mechanical properties of the bulk components were assessed using a Vickers Microhardness tester. The test results demonstrated an improvement in the hardness of Mg-doped components. Higher hardness values were also reported with an increase in the cryomilling duration. This article discusses the mechanisms for the reduction in crystallite size for pure Al and Al-3Mg and its subsequent impact on improving mechanical properties.

Influence of Cryomilling on Crystallite Size of Aluminum Powder and Spark Plasma Sintered Component.

The present investigation aims to develop nanocrystalline (NC) pure aluminum powders using cryomilling technique and manufacture bulk components using spark plasma sintering (SPS). The cryomilling was performed on pure Al powders for 2, 6, and 8 h. The cryomilled powders were then consolidated using SPS to produce bulk components. The particle morphology and crystallite size of the powders and the bulk SPS components were analyzed using scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The results showed that the crystallite size of pure Al powders decreases with increased cryomilling time. The results also showed that the SPS at elevated temperatures resulted in a slight increase in crystallite size, however, the changes were insignificant. The mechanical properties of the bulk components were determined using a Vickers microhardness tester. The hardness of the cryomilled SPS component was determined to be three times higher than that of the unmilled SPS component. The mechanism for the reduction in crystallite size with increasing cryomilling time is discussed. This fundamental study provides an insight into the development of bulk nanomaterials with superior mechanical properties for automotive, aerospace, marine, and nuclear applications.

Peening Techniques for Surface Modification: Processes, Properties, and Applications.

Surface modification methods have been applied to metals and alloys to change the surface integrity, obtain superior mechanical properties, and improve service life irrespective of the field of application. In this review paper, current state-of-the-art of peening techniques are demonstrated. More specifically, classical and advanced shot peening (SP), ultrasonic impact peening (UIP), and laser shock peening (LSP) have been discussed. The effect of these techniques on mechanical properties, such as hardness, wear resistance, fatigue life, surface roughness, and corrosion resistance of various metals and alloys, are discussed. This study also reports the comparisons, advantages, challenges, and potential applications of these processes.

Role of intraoperative echocardiography in surgical correction of the superior sinus venosus atrial septal defect.

Superior type of sinus venosus atrial septal defect (SVASD) is invariably associated with the unroofing of right upper pulmonary vein (RUPV). Warden procedure and pericardial patch repair with rerouting of the RUPV are commonly performed operations for the superior SVASD. Both operations involve the risk of obstruction to the flow of superior vena cava or rerouted pulmonary vein in the postoperative period. The sinus venosus defects are well visualized on the transesophageal echocardiography (TEE) because of the proximity of the TEE probe to these structures. We are reporting two cases operated for the superior SVASD with unroofed RUPV, highlighting the intraoperative echocardiographic features before and after the surgery.

Tricuspid valve excision using off-pump inflow occlusion technique: role of intra-operative trans-esophageal echocardiography.

A pacing system infection may lead to infective endocarditis and systemic sepsis. Tricuspid valve surgery may be required if the valve is severely damaged in the process of endocarditis. Although, cardiopulmonary bypass is the safe choice for performing right-heart procedures, it may carry risk of inducing systemic inflammatory response and multi-organ dysfunction. Some studies have advocated TV surgery without institution of CPB. We report tricuspid valve excision using the off-pump inflow occlusion technique in a 68-year-old man. We also describe role of intra-operative TEE as a monitoring tool at different stages of the surgical procedure.

Early results of minimally invasive mitral valve surgery: initial series in a public hospital in Australia.

PURPOSE: This study analyzes the initial experience with minimally invasive mitral valve surgery through a right minithoracotomy in a public teaching hospital in Australia and evaluates early surgical outcomes. METHODS: A retrospective review of patients who underwent minimally invasive mitral valve surgery between November 2006 and March 2009 was performed. RESULTS: A total of 60 patients included 47 (78%) patients who had mitral valve plasty and 13 (22%) who had mitral valve replacement. The mean age was 61 ± 15 years; 33 (55%) patients were male; and 6 (10%) had had previous cardiac operations. The mean cardiopulmonary bypass and aortic cross-clamp times were 140 ± 46 and 93 ± 35 min, respectively. All patients who underwent mitral valve plasty left the operation room with no more than trivial residual mitral regurgitation. There was no operative mortality. Reoperation for bleeding and stroke occurred in 2 patients each. The mean intensive care unit and hospital stays were 3.1 ± 5.8 and 10.6 ± 8.9 days, respectively. Among the 47 patients with mitral valve plasty, 46 (98%) had mild or less mitral regurgitation on transthoracic echocardiography at discharge. There was one late death. No reoperation for the mitral valve has been observed so far. An echocardiography report was obtained for 34 of the 47 who had had mitral valve plasty at 12.1 ± 7.9 months postoperatively, and 27 (79%) of them had mild or less mitral regurgitation. CONCLUSION: Minimally invasive mitral valve surgery through a right minithoracotomy was safely performed with no early mortality.

Intra-operative assessment of biventricular function using trans-esophageal echocardiography pre/post-pulmonary thromboembolectomy in patient with chronic thromboembolic pulmonary hypertension.

Postoperative studies in patients with chronic thromboembolic pulmonary hypertension (CTPH) have shown that pulmonary thromboembolectomy (PTE) results in a rapid decrease of right ventricular (RV) size, improvement in the RV systolic function and left ventricular (LV) diastolic function. However, the extent to which the biventricular function recovers immediately after embolectomy in post-cardiopulmonary bypass period is not clear. A 45-year-old male patient was operated for retrieval of thrombus from pulmonary trunk and right pulmonary artery. Intraoperative transesophageal echocardiography (TOE) before surgery revealed signs of RV dysfunction and enlargement. The interventricular septum was seen moving paradoxically during end-systole and early-diastole. E/A ratio on transmitral Doppler flow velocity profile was about 0.63 and S/D ratio on pulmonary venous Doppler profile was 2.25, indicative of LV diastolic dysfunction. After weaning the patient from bypass, navigation on TOE showed marginal recovery of the RV systolic function and abatement of septal paradox to some extent. However, significant improvement was observed in the LV diastolic parameter (normal E/A ratio, S/D ratio of 1.08). We conclude that the geometrically altered LV recovers more than the hypertrophied and hypokinetic RV in a patient with CTPH in the post-bypass period.

Late presentation of aortic root abscess in endocarditis with coronary ischemia.

Formation of a large aortic root abscess is an infrequent complication of aortic valve endocarditis in adults. Extrinsic compression of the coronary arteries by this abscess is still rarer. Here, we report a case of a 22-year-old male with aortic root abscess, who presented 2 months after the completion of treatment of endocarditis with exertional angina. Coronary angiogram revealed compression of proximal left anterior descending and left circumflex arteries by the abscess. The patient was successfully treated with pericardial patch exclusion of the abscess cavity and coronary artery bypass graft. The presentation of aortic root abscess with myocardial ischemia as a late complication of treated endocarditis has not been reported earlier.

Subannular left ventricular pseudoaneurysm following mitral valve replacement.

Delayed development of left ventricular pseudoaneurysm is a rare late complication of mitral valve prosthesis and requires early surgical intervention. Here we describe the occurrence of such a complication diagnosed 6-months after the valve surgery in a 60-year-old lady. The anatomic delineation of subannular left ventricular pseudoaneurysm using multiple imaging modalities including CT angiography is also being discussed.

Does transfusion of residual cardiopulmonary bypass circuit blood increase postoperative bleeding? A prospective randomized study in patients undergoing on pump cardiopulmonary bypass.

OBJECTIVE: Homologous blood transfusion after open heart surgery puts a tremendous load on the blood banks. This prospective randomized study evaluates the efficacy of infusing back residual cardiopulmonary bypass (CPB) circuit i.e., pump blood as a means to reduce homologous transfusion after coronary artery bypass surgery (CABG) and whether its use increases postoperative drainage. MATERIALS AND METHODS: Sixty-seven consecutive patients who underwent elective CABGs under CPB were randomized into 2 groups: (1) cases where residual pump blood was used and (2) controls where residual pump blood was not used. Patients were monitored for hourly drainage on the day of surgery and the 1(st) postoperative day and the requirements of homologous blood and its products. Data were matched regarding change in Hemoglobin, Packed Cell Volume and coagulation parameters till 1st postoperative day. All cases were followed up for three years. RESULTS: There was a marginal reduction in bleeding pattern in the early postoperative period in the cases compared to controls. The requirement of homologous blood and its products were also reduced in the cases. CONCLUSIONS: The use of CPB circuit blood is safe in the immediate postoperative period. The requirement of homologous blood transfusion can come down if strict transfusion criteria are maintained.

The 'aortic rim' recount: embolization of interatrial septal occluder into the main pulmonary artery bifurcation after atrial septal defect closure.

INTRODUCTION: Percutaneous device closure of atrial septal defect (ASD) has emerged as an alternative to traditional surgical closure. Although reduced hospital stay, decreased morbidity and absence of a surgical incision are beneficial, other procedure- or device-related complications are coming into light. We report a rare complication of early embolization of the Blockaid septal occluder into the main pulmonary artery bifurcation associated with 'aortic rim' erosion and present a brief review of literature pertaining to the high incidence of complications associated with deficient or eroded 'aortic rims' necessitating surgical intervention. MATERIALS AND METHODS: An 18-year-old male underwent successful percutaneous device closure of a 24.5 mm ASD after fulfilling institutional criteria for the procedure. The device used was a Blockaid septal occluder, a device morphologically similar to the Amplatzer device. The subsequent day, he had embolization of the device into the main pulmonary artery bifurcation, and underwent emergency surgical retrieval of the same with closure of the ASD. At surgery the ASD was found to have an eroded aortic rim. COMMENTS: We believe that embolization of the percutaneous septal occluder in our patient was due to a combination of factors including an inadequate aortic rim; a grossly oversized device which eroded the aortic rim; and the Blockaid septal occluder, whose formally untested design and configuration could have led to its migration. CONCLUSION: Strict selection criteria governing an 'adequate' aortic rim, the size of the device, and the choice of the device may help reduce the incidence of complications like the rare, but potentially fatal embolization of the device into the pulmonary artery following percutaneous device closure of an ASD.

Scimitar syndrome with anomalous connection of left superior pulmonary vein to left innominate vein.

Scimitar syndrome is a rare variant of partial anomalous pulmonary venous connection. The combination of scimitar syndrome with anomalous connection of the left superior pulmonary vein to the left innominate vein is extremely rare, and is yet to be documented in literature. We report the successful single-stage correction of such a rare type of anomalous pulmonary venous connection.

Fatal post-operative gastro intestinal hemorrhage because of angio-dysplasia of small intestine in aortic regurgitation.

Gastrointestinal bleeding due to angiodysplasia of the large intestine associated with calcific aortic stenosis is a well-known entity. Angiodysplasias are artero-venous malformations and they form one of the common causes of occult gastro-intestinal bleeding in the elderly. A 59-year-old man underwent aortic valve replacement for severe aortic regurgitation, developed severe gastro intestinal bleeding. Selective angiography was inconclusive. Exploratory laparotomy revealed angiodysplasia of the terminal ileum, which was resected. We report this case to draw attention to this rare cause of gastro intestinal bleeding and the difficulty in arriving at a diagnosis by the usual investigations.