External Wrapping Research Articles

Focusing on papain release in the intestine: The effects of Chitinous materials on alginate microsphere properties

SummaryExogenous enzymes, accompanied by a function of assisting digestion, can be employed in therapeutic application which supplement the daily diet for the patients suffering from gastrointestinal diseases. To prevent the degradation of the enzymes in gastric fluid, papain was encapsulated into alginate microspheres with the external wrap of chitin nanocrystals. The protective effect of the assembled alginate microspheres (PAM‐ChNC) on papain was studied and compared with traditional chitosan‐coated alginate microspheres (PAM‐Ch). Scanning electron microscopy results showed that ChNC could form a dense structure on the surface of alginate microspheres. The swelling rate of PAM‐ChNC was lower than that of PAM‐Ch at pH 1.2. The effect of papain (encapsulated in microspheres) on the digestion of myofibrillar protein gels (MP) was investigated by in vitro digestion. The results showed that the degree of hydrolysis of MP + PAM‐ChNC was significantly higher than that of MP+ PAM‐Ch, indicating that PAM‐ChNC was expected to become a controlled release system for oral exogenous enzymes that assist digestion.

Performance and strengthening of the circular R.C. Columns with high slenderness ratios using GFRP External Wrapping

Performance and strengthening of the circular R.C. Columns with high slenderness ratios using GFRP External Wrapping

Biodegradable external wrapping promotes favorable adaptation in an ovine vein graft model

Vein grafts, the most commonly used conduits in multi-vessel coronary artery bypass grafting surgery, have high intermediate- and long-term failure rates. The abrupt and marked increase in hemodynamic loads on the vein graft is a known contributor to failure. Recent computational modeling suggests that veins can more successfully adapt to an increase in mechanical load if the rate of loading is gradual. Applying an external wrap or support at the time of surgery is one way to reduce the transmural load, and this approach has improved performance relative to an unsupported vein graft in several animal studies. Yet, a clinical trial in humans has shown benefits and drawbacks, and mechanisms by which an external wrap affects vein graft adaptation remain unknown. This study aims to elucidate such mechanisms using a multimodal experimental and computational data collection pipeline. We quantify morphometry using magnetic resonance imaging, mechanics using biaxial testing, hemodynamics using computational fluid dynamics, structure using histology, and transcriptional changes using bulk RNA-sequencing in an ovine carotid-jugular interposition vein graft model, without and with an external biodegradable wrap that allows loads to increase gradually. We show that a biodegradable external wrap promotes luminal uniformity, physiological wall shear stress, and a consistent vein graft phenotype, namely, it prevents over-distension, over-thickening, intimal hyperplasia, and inflammation, and it preserves mechanotransduction. These mechanobiological insights into vein graft adaptation in the presence of an external support can inform computational growth and remodeling models of external support and facilitate design and manufacturing of next-generation external wrapping devices. Statement of significanceExternal mechanical support is emerging as a promising technology to prevent vein graft failure following coronary bypass graft surgery. While variants of this technology are currently under investigation in clinical trials, the fundamental mechanisms of adaptation remain poorly understood. We employ an ovine carotid-jugular interposition vein graft model, with and without an external biodegradable wrap to provide mechanical support, and probe vein graft adaptation using a multimodal experimental and computational data collection pipeline. We quantify morphometry using magnetic resonance imaging, mechanics using biaxial testing, fluid flow using computational fluid dynamics, vascular composition and structure using histology, and transcriptional changes using bulk RNA sequencing. We show that the wrap mitigates vein graft failure by promoting multiple adaptive mechanisms (across biological scales).

Experimental and numerical study of compressive behavior of axially loaded circular ultra-high-performance concrete-filled tube columns

To test the compressive behavior of ultra-high-performance fiber-reinforced concrete UHPFRC columns, numerical and experimental investigations were conducted using various confinement materials under axial compression loading. A total of seven columns were examined in the current experimental work. In this study, the major variables included the utilization of an outer steel tube, an inner steel tube, an outer polyvinyl chloride (PVC) tube, and an external wrap by CFRP, i.e., carbon fiber- reinforced polymer wrap. For UHPFRC-filled tube columns, a 3D finite element (FE) simulation has been developed. The commercial FE program ABAQUS was used. Moreover, validation against the obtained experimental results was carried out. The results showed that the outer steel tube had a better confinement impact on the given core concrete compared with the PVC tube and the CFRP sheet. The axial capacity of the column specimens confined with steel, PVC and CFRP was enhanced about 53 %, 13 %, 27 % compared to control specimens. All proposed confinement schemes improved the columns’ ductility and energy absorption considerably. Furthermore, the simulation results confirmed the reasonableness of the FE model of specimens to a significant extent; thus, they can be reliable to produce more predictions.

External Aortic Wrapping for Type A Dissection: SEWing but Not as We Know It

In their fascinating article in this issue of The Annals of Thoracic Surgery, Suematsu and colleagues1 present their experience of performing stepwise external wrapping (SEW) of the aorta for patients with type A aortic dissection deemed at excessive risk for conventional surgical repair. In this cohort of 43 patients with a mean age of 79 years, a median EuroSCORE (European System for Cardiac Operative Risk Evaluation) II of 63.9 the operative mortality was only 2.3%. Cerebral malperfusion was present in 65% of patients preoperatively; however, only 2 patients had persistent postoperative neurological disorders.

Aortic Remodeling After Stepwise External Wrapping for Type A Acute Aortic Dissection

BackgroundThe optimal repair technique for type A acute aortic dissection is graft replacement; however, the treatment approach in high-risk patients remains controversial or suboptimal. MethodsWe have retrospectively analyzed a cohort of high-risk patients who were admitted to our center for type A acute aortic dissection and who were treated by a new surgical approach using artificial grafts (stepwise external wrapping) between January 2016 and January 2020. The primary endpoints included inhospital mortality and survival during follow-up. Secondary endpoints included the assessment of aortic remodeling after ascending aorta wrapping. ResultsAmong the 134 patients admitted for type A acute aortic dissection, 43 patients underwent stepwise external wrapping. The mean patient age was 79.1 ± 6.8 years. The new standard European System for Cardiac Operative Risk Evaluation score was 64% ± 12%. There was one hospital death (2.3%). There were two major complications of persistent cerebral disorder (4.6%). Minor complications included temporary neurologic disorder (2.3%) and renal failure (2.3%). The intensive care unit and hospital stays were 2.8 ± 1.0 days and 11.7 ± 2.5 days, respectively. The follow-up survival rate was 95.3% ± 6.2% and 91% ± 10.2% at 1 and 3 years, respectively, after surgery. There was no aortic-related death during follow-up. At 1 year after surgery, complete remodeling of the ascending aorta was obtained in 30 patients (85.7%), and 5 patients (14.3%) showed partial remodeling. ConclusionsOur stepwise external wrapping technique was associated with excellent outcomes for high-risk patients with type A acute aortic dissection.

High dilutions of Magonia pubescens hidrogel affect germination variables in Sorghum bicolor L. Moench

High dilutions of Magonia pubescens hidrogel affect germination variables in Sorghum bicolor L. Moench

Reliability-based optimization of external wrapping of CFRP on reinforced concrete columns considering decayed diffusion

A cost-efficient maintenance plan is crucial to ensure the reliability of decayed reinforced concrete (RC) structures. A reliability-based optimization strategy is proposed that considers a time-variant deterioration model for planning the optimal time and degree of carbon-based fiber reinforcement polymer (CFRP) strengthening of RC columns. A genetic algorithm (GA) has been used as an optimization tool, and the particle swarm optimization algorithm was used to validate the outcomes. A deteriorating RC column exposed to chloride attack was modeled to compare the time-dependent failure probabilities calculated by a recently-developed closed-form equation and the correspondent reliability indexes as lifetime performance indicators. The influence of CFRP wraps on the decayed diffusion rate, and corrosion current density has been modeled using existing formulations. The results of the decaying diffusion model also have been compared to the extreme cases of “no influence” and “complete corrosion stop”. It was found that a GA can successfully determine the optimum solution in terms of the number of required CFRP layers and strengthening time to yield the minimum life-cycle costs. The findings can assist engineers and asset owners in providing optimized maintenance and repair strategies for decayed structures. It also highlights the significance of proper modeling of the corrosion process in CFRP-strengthened RC columns.

Linear plication and external wrapping in ascending aortic aneurysm in well-selected patients: Surgical technique

An aortic aneurysm is known as a bulging or dilatation of the aorta for more than one and half of its normal diameter result in making the wall of the aorta thinner and at the risk of dissection or rupture. For a long time ago surgeons have worked hard to find the best surgical technique to treat this pathology. Open surgery with the replacement of the aneurysmatic segment by a synthetic graft is still the standard surgical treatment method. In the past, some surgeons tried patching the aneurysmatic segment with synthetic patches. This technique was not accepted by many surgeons. In our cardiovascular surgical center, we perform linear plication and external wrapping (LPEW) surgical technique for more than ten years in well-selected patients whose aortic aneurysm diameter is less than 6 cm with normal aortic root and who has not any connective tissue disease, dissection, or rupture. Our results are satisfying with low morbidity and mortality.

Analytical Stress-Strain model for BFRP strengthened RC columns under axial loading

Reinforced column with external wrapping of FRP (Fiber Reinforced Polymer) is one of the strengthening methods. The objective of this experimental work is to determine the axial stress and strain capacity of BFRP (Basalt Fiber Reinforcement Polymer) strengthened RC columns (Reinforced Concrete) under axial loading. The dimension of RC square cross section column 100 mm × 100 mm with λ = 10 (slenderness ratio) and RC circular column of diameter 150 mm with λ = 6.67 (slenderness ratio) are externally strengthened by BFRP layers as per the ACI 440.2R-8 code. All the columns are casted at the depth of 1000 mm. The parameters studies are, shape of the columns (square and circular) and number of BFRP layers (one, two and three). Result discussed about the unconfined and BFRP confined RC columns stress–strain response, deformation control, lateral confining pressure and cost analysis. It is concluded that the RC short circular column confined with BFRP three layers offer more resistance to buckling and has greater load carrying capacity than that of the unconfined circular column and BFRP confined square columns. The ultimate stress and strain equations were predicted from the trend line drawn for BFRP strengthened RC square and circular columns.

Experimental Study on PCC Beams Strengthened With External Wrapping of Basalt Fibre Reinforced Polymer (BFRP)

Infrastructure plays a vital role in development for recent times and humiliation of structural materials that is caused by some environmental effects has to be protected by strengthening of structures. One of the finest challenges in Civil Engineering is strengthening and rehabilitation of existing structures. There are various rehabilitation technique such as external wrapping of fiber reinforced polymers (FRP) have been developed. At initial period, strengthening has been done externally using steel plates bonded to the tension side and it has numerous difficulties including durability, manipulation, and heavy weight. The main aim of the study is to investigate the flexural behavior of the PCC beam with respect to orientation of the wrapped basalt fiber reinforced polymer (BFRP). A sequence of 12 PCC beams with 500mm as its length, 100mm as its width and 100mm as its depth are cast with M25 grade concrete. All the 12 specimens are cured for a period of 28 days. Of the 12 PCC beams two beams are control specimens and a comparative study on the orientation of the fiber such as wrapped tension zone, shear zone, U shaped-1, U shaped-2, and fully wrapped are used on the specimen. The fiber is to be wrapped according to the orientation of the beam with epoxy resin. The experimental results shows that PCC beam that is wrapped as U shaped – 2 Shows higher Flexural strength compared to all other fabric orientations. BFRP Fully wrapped beam gives minimum Load carrying capacity when compare with other fabrics. U shaped – 2 orientation has higher load carrying capacity and economical as compared to fully wrapped and all other modes of orientations.

Effectiveness of FRP strengthening on buckling characteristics of metallic cylindrical shells

Buckling performance of thin metallic shells can be enhanced by external wrapping of FRP composite layers. But the effectiveness and the extent of such FRP strengthening is influenced by the buckling characteristics of the metallic shell. This paper presents a detailed numerical study to bring out the changes in buckling behaviour and buckling modes of metallic cylindrical shells of different r/t ratios, exhibiting all varieties of buckling viz. elastic, axisymmetric plastic, and asymmetric plastic, due to changes in the hoop and longitudinal stiffness of the FRP wrap. The most general buckling behaviour of the FRP strengthened shells exhibiting elastic, pre-strain localization, post strain localization, axisymmetric buckle growth, and the asymmetric buckle growth stages are being brought out. Subsequently, the influence of parameters viz. r/t ratio, modulus and yield strength of the metallic shell, and the type and magnitude of the FRP strengthening on this general buckling behaviour are analysed. The results demonstrate that 1) the elastic buckling shells display a stepwise increase in load capacity with an increase in hoop modulus of the FRP wrap; 2) for the plastic buckling shells undergoing asymmetric buckling modes, a minimal increase in longitudinal stiffness of FRP wrap, just sufficient to reach the shells’ yield capacity, would lead to an optimal design; and 3) for the plastic buckling shells failing due to axi-symmetric bulging at their ends, the increase in longitudinal stiffness of FRP, increases both the yield capacity and the pre-strain localization stiffness, leading to a large increase in buckling capacity.

Compressive Strength of FRP-Reinforced and Confined Concrete Columns

Nowadays, the practice of fiber-reinforced polymers (FRPs) as an internal reinforcement and external wrapping has been expanded in the construction industry. No theoretical model for estimating the compressive strength (CS) of FRP bars reinforced concrete (RC) columns wrapped with FRP sheets (FRCFS columns) has been found in the literature. The main goal of the current research work is to recommend a new theoretical model for estimating the CS of FRCFS columns. To secure the aims of the present work, the previous research works were employed to construct two different records. The first record consists of 500 sample points of FRP-wrapped concrete specimens, and the second record consists of 269 sample points of FRP bars RC columns. Some initial assessments were carried out on the collected records to select the most suitable forms of the recommended models for FRP-wrapping and CS of FRP bars RC columns. The estimations of these models presented higher accuracy as compared with the previously recommended models. Finally, a new theoretical model was recommended for the CS of FRCFS columns. Then, an extensive parametric study of 216 specimens of FRCFS columns was carried out using the recommended theoretical model.

Hybrid stepwise external wrapping for type a acute aortic dissection with cerebral Malperfusion

BackgroundAcute aortic dissection (AAD) is a life-threatening condition which can lead to coronary, brachiocephalic or branch vessel malperfusion, as well as aortic valve insufficiency, or aortic rupture. Mortality of surgical treatment in high-risk or elderly patients with Type A AAD (TAAAD) still remains high, and treatment for such patients remains controversial. We report a successful treatment of TAAAD with a communicating false lumen in a 60-year-old man with acute hemi-cerebral malperfusion.Case presentationThe ascending aorta was wrapped with stepwise external wrapping (SEW) procedure, and subsequent thoracic endovascular aortic repair (TEVAR) was successfully performed. The patient was discharged in good physical condition without any complications.ConclusionsHybrid therapy with SEW and TEVAR with TAAAD associated with major cerebral malperfusion should be considered, especially in patients for whom open surgery is extremely risky.

P24 The Serious Danger of Using Reduction Aortoplasty With External Wrapping to Treat Ascending Aortic Aneurysms

There are multiple surgical methods in use internationally to treat ascending aortic aneurysms. One such controversial technique is the use of reduction aortoplasty with external wrapping. We present a case which highlights the grave dangers of using external wrapping to treat ascending aortic aneurysms.

Experimental Investigation on the Ecofriendly External Wrapping of Glass Fiber Reinforced Polymer in Concrete Columns

An ecofriendly fiber reinforced polymer (FRP) had been used in the last decade to enhance the short concrete column’s strength and deformation capacity. This study involves the wrapping of FRP sheets with a thickness of 3 mm and 5 mm on a short column, and then the compressive strength is determined. The rectangular columns of size 150 mm × 300 mm are used for this study, and cast under the grades of M20 and M40 are wrapped with GFRP sheets at the thickness of 3 mm and 5 mm. These results are clarified at a specific thickness of the FRP‐wrapped columns. It provides a maximum axial compressive strength, and Young’s modulus gets enhanced rigorously when it is to be compared to the normal concrete. This thesis deals with experimental studies of different parameters associated with wrapped glass fiber reinforced polymer (GFRP). In M20 grade, when the 3 mm wrapped specimen and the 5 mm wrapped specimen are compared, the specimen wrapped with 5 mm increases 5.182% more than the specimen wrapped with 3 mm. In M40 grade, when the 0 mm, 3 mm, and 5 mm wrapped specimens are compared, the specimen wrapped with 5 mm increases 2.47% more than the specimen wrapped with 0 mm. The 5 mm wrapping attains the maximum strength.

Оригінальний метод лікування аневризми висхідного відділу аорти

The need for surgical treatment of ascending aortic aneurysms is due to a number of severe complications that occur during the natural course of the disease, such as aortic dissection and rupture. Such interventions show good immediate and long-term treatment outcomes, but they are often accompanied by high blood loss and surgical trauma, which in elderly patients with concomitant pathology can lead to serious cardiac and extracardiac complications and prolongation of treatment in general. We present a technology of external wrapping of the aorta that reduces surgical trauma while maintaining effect of operation. A clinical case of application of this technology in a 63-year-old patient hospitalized to the clinic of the Heart Institute, Ministry of Health of Ukraine, with a diagnosis of aortic insufficiency of the 3rd degree (tricuspid aortic valve), dilatation of the root and ascending aorta, tricuspid insufficiency of the 2nd degree, high pulmonary hypertension, heart failure with reduced left ventricular systolic function. The use of the proposed method has following advantages compared to the established method of fixation of the vascular prosthesis: fixation of the proximal part of the vascular prosthesis is performed using vascular suture material; elimination of the risk of damage to the aortic wall; elimination of the risk of massive bleeding from the aorta at the site of the prosthesis fixation; decreased duration of surgery. Key words: aortic aneurysm, surgical treatment, wrapping of the ascending aorta.

Strength and Durability of Concrete Cubes and Cylinders Wrapped with FRP

Experimental were conduct on the distressed reinforced cement concrete compressive element and on the same after they have been retrofitted for rehabitation. Presently, FRP materials are also been started use in construction field in the form of wrapping to enhance the load carrying capacity, shear and flexural strength as well as ductility. This is an experiment based project which deals with strengthening and load deformation relationship of reinforced cement concrete. Mix design is done M 30 grade of concrete as per IS: 10262-2009 for preparation of structural elements. In this research, increases in strength, stiffness and durability due to external wrapping of Carbon Fiber Reinforced Polymer (CFRP) sheets on concrete cylinders were studied. The research focused on behavior of plain and wrapped concrete cylinders with respect to parameters such as concrete compressive strength, fiber orientation of CFRP wrap. The experimental results were correlated to analytical models consisting of terms representing lateral pressure generated by the wrap in hoop direction. Keywords: Strength , Durability, Cylinder Wrapped, compressive elements

A NUMERICAL STUDY ON SEISMIC PERFORMANCE EVALUATION OF RC RECTANGULAR COLUMNS STRENGTHENED WITH CFRP SHEETS

External confinement of reinforced concrete columns using fiber-reinforced polymer (FRP) sheets can significantly enhance their seismic behavior. This research presents a numerical investigation to evaluate the seismic performance of RC rectangular columns with limited cross-sections' aspect ratios (1, 1.5, and 2) strengthened with a fully wrapped CFRP jacket under constant axial and pushover lateral loads. Therefore, a three-dimensional finite element model was implemented via ABAQUS software, which has been adopted in this study, where the proposed model showed a reliable agreement with the previous experimental work. The studied parameters are: longitudinal steel reinforcement ratio, CFRP confinement ratio, and axial load/capacity ratio for each cross-section aspect ratio. The obtained numerical results have proved that the external wrapping of RC rectangular columns with CFRP sheets has effectively increased drift capacity ratios for cross-sections aspect ratios 1, 1.5, and 2. Moreover, the strengthening of RC rectangular columns using external CFRP wrapping increases the nominal shear and flexural strengths of the strengthened columns. Also, the effect of increasing the longitudinal steel reinforcement ratio can significantly decrease the ultimate lateral displacement and drift capacity ratios. Besides, with the increase of the axial load/capacity ratios, the drift capacity ratios significantly decrease for the strengthened RC rectangular columns.

Stepwise external wrapping procedure for type A intramural hematoma.

The optimal treatment for Stanford type A acute intramural hematoma remains controversial, especially in elderly or high-risk patients. We have developed a new surgical approach using artificial grafts (stepwise external wrapping) for high-risk patients. The aim of this study is to report our results using the stepwise external wrapping procedure in the treatment of high-risk patients with type A intramural hematoma. Among the 129 patients admitted for type A intramural hematoma between January 2016 and January 2020, 49 patients underwent stepwise external wrapping. The mean patient age was 78±7years. The new standard European system for cardiac operative risk evaluation II was 54%±23%. The mean overall operation and cardiopulmonary bypass times were 96±13minutes and 35±10minutes, respectively. There were no hospital deaths. Two cases of temporary neurologic disorder, 1 case of renal failure, and 2 cases of wound infection occurred during the postoperative period. The intensive care unit and hospital stays were 2±1days and 10±3days, respectively. The thickness of intramural hematoma that had been the target of the stepwise external wrapping procedure decreased significantly from 18.0±10.7mm preoperatively to 5.2±4.4mm at 3months after surgery (P<.05). The follow-up survival was 97.7%±4.4 % at 1year after surgery and 89.8%±11.4% at 3years after surgery. There was no aortic-related death during follow-up. Our stepwise external wrapping is a feasible alternative to conventional graft replacement for high-risk patients with type A intramural hematoma. The early and midterm outcomes of the procedure were satisfactory, but further careful follow-up is needed.