Damaged Portion Research Articles

Drp1-Zip1 Interaction Regulates Mitochondrial Quality Surveillance System

Mitophagy, a mitochondrial quality control process for eliminating dysfunctional mitochondria, can be induced by a response of dynamin-related protein 1 (Drp1) to a reduction in mitochondrial membrane potential (MMP) and mitochondrial division. However, the coordination between MMP and mitochondrial division for selecting the damaged portion of the mitochondrial network is less understood. Here, we found that MMP is reduced focally at a fission site by the Drp1 recruitment, which is initiated by the interaction of Drp1 with mitochondrial zinc transporter Zip1 and Zn2+ entry through the Zip1-MCU complex. After division, healthy mitochondria restore MMP levels and participate in the fusion-fission cycle again, but mitochondria that fail to restore MMP undergo mitophagy. Thus, interfering with the interaction between Drp1 and Zip1 blocks the reduction ofMMP and the subsequent mitophagic selection of damaged mitochondria. These results suggest that Drp1-dependent fission provides selective pressure for eliminating "bad sectors" in the mitochondrial network, serving as a mitochondrial quality surveillance system.

Rehabilitation of Reinforced Concrete Deep Beams Using Carbon Fiber Reinforced Polymers (CFRP)

Reinforced concrete structures that incorporates deep beams are generally susceptible to deterioration due to weathering effects and sulphur attacks, under-design in the detailing of concrete cover and/or reinforcement, and construction errors. In lieu of demolishing and replacing these structures, rehabilitation and strengthening using carbon fiber composites becomes a cost-effective viable alternative. Recent advances in research and innovation have introduced concrete repair and strengthening systems that are primarily based on fiber reinforced polymer composites. These systems have offered engineers the opportunity to provide additional stability to the structural elements in question and to restore the damaged portions back to their original load carrying capacity. This paper investigates the effect of Carbon Fiber Reinforced Polymer (CFRP) composites in enhancing the flexural performance of damaged reinforced concrete deep beams. Two types of CFRP composites and epoxy were used in the experimental investigation carried out and as described by this paper: 1) high strength carbon fiber reinforced polymer (CFRP) plates, commercially known as MBrace Laminate, that are bonded using an epoxy resin specifically suited for the installation and used to strengthen existing structural members; and, 2) MBrace Fiber 230/4900, a 100% solids, low viscosity epoxy material that is used to encapsulate MBrace carbon, glass, and aramid fiber fabrics so that when it cures, it provides a high performance FRP sheet.Test samples were divided into four groups: A control group, and three rehabilitated test groups with CRFP fibers, where the main variable among them was the percent length of CRFP used along the bottom beam extreme surface between supports (i.e, for two of the groups reinforced with MBrace laminates), and the use of MBrace Fiber 230/4500 CRFP sheets on the 4th beam along its vertical sides as well as the bottom extreme face between supports. All beams had similar cross-sectional dimensions and reinforcement, and were designed to fail in flexure rather than shear. The results show that CFRP composites, both laminated and sheet type, have increased the load carrying capacity in comparison to the control specimen, where observations were recorded pertaining to the delayed formation of vertical flexural cracks at the section of maximum moment, and diagonal shear cracks at beam ends. The increase in the load carrying capacity varied among the three rehabilitated test group beams, with the 4th group showing the highest ultimate load carrying capacity when compared to the control specimen.

A multilayer scaffold design with spatial arrangement of cells to modulate esophageal tissue growth.

Esophageal diseases may require resectioning of the damaged portion. The current standard of care requires the replacement of the esophagus with the stomach or the intestine. Such procedures have high rates of mortality and morbidity; therefore, the use of alternative conduits is needed. A tissue engineering approach that allows for the regeneration of esophageal tissues would have significant clinical application. A cell-seeded synthetic scaffold could replace the resected part of the esophagus and elicit tissue regrowth. In order to ideally recreate a functioning esophagus, its two crucial tissue layers should be induced: an epithelium on the luminal surface and a muscle layer on the exterior surface. To create a bioengineered esophagus with both tissue layers, a multilayer (ML) tubular scaffold design was considered. Luminal and exterior layers were electrospun with broad pore size to promote penetration and proliferation of mesenchymal stem cells on the lumen and smooth muscle cells on the external. These two layers would be separated by a thin layer with substantially narrower pore size intended to act as a barrier for the two cell types. This ML scaffold design was achieved via electrospinning by tuning the solution and the process parameters. Analysis of the scaffold demonstrated that this tuning enabled the production of three integrated layers with distinguishable microstructures and good mechanical integrity. In vitro validation was conducted on the separated unilayer components of the ML scaffold. The resultant proof-of-concept ML scaffold design could possibly support the spatial arrangement of cells needed to promote esophageal tissue regeneration. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 107B: 324-331, 2019.

The effect of galling aphids feeding on photosynthesis photochemistry of elm trees (Ulmus sp.)

Changes of chlorophyll (Chl) a fluorescence and photosynthetic pigment contents were analysed in galled leaves (visibly damaged and undamaged parts) and intact leaves. The values of minimal fluorescence of the dark-adapted state, maximal quantum yield of PSII photochemistry, effective quantum yield of PSII photochemical conversion, and photochemical quenching coefficient decreased in Ulmus pumila L. leaves galled by Tetraneura ulmi (L.) and in U. glabra Huds. galled by Eriosoma ulmi (L.). Colopha compressa (Koch.) feeding affected these parameters only in damaged parts of U. laevis Pall. galled leaves. The increasing number of T. ulmi galls progressively decreased photosynthetic performance. In gall tissues of all analysed aphid species, the lowest photosynthetic pigment content was found, indicating that the photosynthetic capacity must have been low in galls. Significant reduction of Chl and carotenoid contents were observed in damaged and undamaged portions of galled leaves only in the case of T. ulmi feeding.

Integrative Immune Stimulation Dynamic in Reversal Processes of Stage Four of Prostate Cancer. A Case Study

BackgroundThe fundamental cause of cancer is the inability of your body to kill cancer cells as fast as they are being created. There has been a great deal of research on Transforming Grow Factors (TGF's, also known as Tumor Growth Factors) and other growth factors, and their impact on the growth of cancer. Toxins and free radicals may damage the genes controlling production of mitochondrial energy production, presumed to be underlying factor in the development of tumors. Pathogens, toxins, the wrong foods, low oxygen, stress and many of the other contributors to cancer may predispose the development of cancer cells. However, it may also be a malfunctioning of the morphic field that causes them to form tumors. There has been apparent reason why a stress, shock or trauma that effects a certain part of the brain is might cause cancer to develop in an organ which is exactly what has been observed. The morphic field is also likely to be damaged by the shock too, and its damaged portion, at least for certain shocks and trauma, the facilitate organization of cells into tumors.Methods and ResearchPatient was diagnosed prostate cancer in year 2010. Cancer mestatascized to his bones, blood, mouth and liver. Doctors considered it Stage 4 (probably incurable). The basic General Mathematical Condition need to be accomplished: G.P. Einstein Velocity of ∑ Quanta Integrative Therapies need to be greater than Velocity of specific genetic mutation cause turning on tumor cancer cells growth. The G. P. Einstein Multi Mathematical Functions of Integrative Immune Stimulation Dynamic Therapies was applied (IISDT). IISDT= F1(∑ therapies Biophysical Quanta Therapies Energy); F2(∑ Biochemical Molar Therapies Energy); F3(∑ Psycho‐neuro E.M.E. Therapies). Vibrational specific frequencies help cause tumors to break up, or to put it another way they tend to cause cancer cells to separate from other cells. The specific energetic frequencies in disrupt the function of cancer cells, helping to facilitate their removal from the body.ResultElectrical conductivity of the cells was dramatically improved by function F1(∑ therapies Biophysical Quanta Therapies Energy). The filter of blood the toxins, dramatically change the diet with controlling the pH of water dramatically improved by function F2 (∑ Biochemical Molar Therapies Energy). The high Oxygenations of total body and brain direct the immune system Integrative Immune Stimulation Dynamic in Reversal Processes of Stage Four of Prostate Cancer. A Case Studymore effectively by function F3(∑ Psycho‐neuro E.M.E. Therapies,ConclusionThe Integrative Immune Stimulation Dynamic in Reversal Processes of Stage Four of Prostate Cancer in spite that classical medicine considered as incurable patient extended his life without surgery or chemotherapy.Support or Funding InformationSupported by Institutional resources of USAT Montserrat and the Einstein Medical Institute, N. Palm Beach, FL USA.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

ACTIVATION OF CARDIAC AUTOPHAGIC FLUX RESCUES ISCHEMIA REPERFUSION INJURY

Reperfusion injury accounts for a significant portion of myocardial damage in acute coronary syndromes. Autophagy, a process of cell catabolism, is vital in the heart's response to stress. We reported that re-induction of ischemia/reperfusion (I/R)-suppressed cardiomyocyte autophagy with histone

Gastroduodenal Artery Pseudoaneurysm: A Complication of Pancreatitis

Acute necrotizing pancreatitis complicated with gastroduodenal artery (GDA) pseudoaneurysm is a very rare (1.5% of all reported visceral arterial aneurysms), life-threatening emergency. Immediate treatment is required to prevent the very high mortality rate. A 77-year-old male with history of atrial fibrillation on apixaban presented with sudden onset diffuse acute abdominal pain, hematemesis, and maroon colored stools. Approximately six weeks prior, he diagnosed with necrotizing acute pancreatitis thought to be induced by dabigatran. At that time, he was discharged in stable condition. On arrival, patient was hypotensive and tachycardic. Patient's abdomen was tender and distended with decreased bowel sounds. His hemoglobin had dropped three grams compared to his last check three weeks ago, and his lactate was 6 mmol/L. CT abdomen with contrast showed significant worsening of underlying acute pancreatitis with necrosis and pseudocyst formation. He was started on intravenous antibiotics and fluids, and apixaban was held. The patient was transferred to the intensive care unit for further management. He remained tachycardic and hypotensive, requiring multiple packed red blood cell transfusions as his hemoglobin continued to drop. Intraabdominal bleeding was strongly suspected. Follow up CT abdomen with contrast showed worsening inflammation and necrosis of the pancreatic bed along with findings of a new 2.8 cm pseudoaneurysm of the GDA near the head of the pancreas. The patient underwent an angiogram, which showed enlarging GDA pseudoaneurysm. Interventional radiology subsequently placed a coil in the area. Signs of intraabdominal bleeding resolved and patient was discharged approximately two weeks later. GDA pseudoaneurysms that rupture have a 40% mortality rate. Pancreatitis is the most common risk factor for formation. Release of proteolytic enzymes combined with the host inflammatory reaction are thought to result in destruction of the vascular wall and localized bleeding which is contained by the surrounding tissues - also known as a pseudoaneurysm. Angiography serves both diagnostic and therapeutic purposes, as embolization proximal to the damaged portion of the artery prevents continued bleeding. Physicians should consider psuedoaneurysm as a cause of hemodynamic instability and acute blood loss anemia in patients with severe necrotizing pancreatitis. Emergent intervention, whether surgery or endovascularly, is needed to prevent death.FigureFigureFigure

Purified Human Skeletal Muscle-Derived Stem Cells Enhance the Repair and Regeneration in the Damaged Urethra.

Postoperative damage of the urethral rhabdosphincter and nerve-vascular networks is a major complication of radical prostatectomy and generally causes incontinence and/or erectile dysfunction. The human skeletal muscle-derived stem cells, which have a synchronized reconstitution capacity of muscle-nerve-blood vessel units, were applied to this damage. Cells were enzymatically extracted from the human skeletal muscle, sorted using flow cytometry as CD34/45 (Sk-34) and CD29/34/45 (Sk-DN/29) fractions, and separately cultured/expanded in appropriate conditions within 2 weeks. Urethral damage was induced by manually removing one third of the wall of the muscle layer in nude rats. A mixture of expanded Sk-34 and Sk-DN/29 cells was applied on the damaged portion for the cell transplantation (CT) group. The same amount of media was used for the non-CT (NT) group. Urethral pressure profile was evaluated via electrical stimulation to assess functional recovery. Cell engraftments and differentiations were detected using immunohistochemistry and immunoelectron microscopy. Expression of angiogenic cytokines was also analyzed using reverse transcriptase-polymerase chain reaction and protein array. At 6 weeks after transplantation, the CT group showed a significantly higher functional recovery than the NT group (70.2% and 39.1%, respectively; P < 0.05). Histological analysis revealed that the transplanted human cells differentiated into skeletal muscle fibers, nerve-related Schwann cells, perineuriums, and vascular pericytes. Active paracrine angiogenic cytokines in the mixed cells were also detected with enhanced vascular formation in vivo. The transplantation of Sk-34 and Sk-DN/29 cells is potentially useful for the reconstitution of postoperative damage of the urethral rhabdosphincter and nerve-vascular networks.

Calcium/calmodulin-dependent protein kinase regulates the PINK1/Parkin and DJ-1 pathways of mitophagy during sepsis.

During sepsis and shock states, mitochondrial dysfunction occurs. Consequently, adaptive mechanisms, such as fission, fusion, and mitophagy, are induced to eliminate damaged portions or entire dysfunctional mitochondria. The regulatory PINK1/Parkin and DJ-1 pathways are strongly induced by mitochondrial depolarization, although a direct link between loss of mitochondrial membrane potential (ΔΨ) and mitophagy has not been identified. Mitochondria also buffer Ca2+, and their buffering capacity is dependent on ΔΨ Here, we characterize a role for calcium/calmodulin-dependent protein kinase (CaMK) I in the regulation of these mechanisms. Loss of ΔΨ with either pharmacologic depolarization or LPS leads to Ca2+-dependent mitochondrial recruitment and activation of CaMKI that precedes the colocalization of PINK1/Parkin and DJ-1. CaMKI is required and serves as both a PINK1 and Parkin kinase. The mechanisms operate in both immune and nonimmune cells and are induced in in vivo models of endotoxemia, sepsis, and hemorrhagic shock. These data support the idea that CaMKI links mitochondrial stress with the PINK1/Parkin and DJ-1 mechanisms of mitophagy.-Zhang, X., Yuan, D., Sun, Q., Xu, L., Lee, E., Lewis, A. J., Zuckerbraun, B. S., Rosengart, M. R. Calcium/calmodulin-dependent protein kinase regulates the PINK1/Parkin and DJ-1 pathways of mitophagy during sepsis.

Abstract 357: Activation of Autophagic Flux Blunts Cardiac Ischemia/Reperfusion Injury

Background: Reperfusion injury accounts for a significant portion of myocardial damage in acute coronary syndromes. Autophagy, a process of cell catabolism, plays a vital role in the heart’s response to stress. We have reported that re-induction of ischemia/reperfusion (I/R)-suppressed cardiomyocyte autophagy with histone deacetylase (HDAC) inhibitors affords significant cardioprotection. However, as HDACs govern many processes and may have off-target effects, we set out to modulate autophagy in a manner independent of HDAC activity. Here, we hypothesized that induction of autophagy with a novel agent, Tat-Beclin, at the time of reperfusion, will reduce I/R injury and rescue cardiac function. Methods: Wild type and ATG7 (protein required for autophagic flux) knockout mice were randomized among 3 treatment groups prior to surgical I/R injury [45 min LAD artery ligation; 24h reperfusion]: vehicle control (VC), Tat-Scrambled (TS), or Tat-Beclin (TB). Each agent was delivered at coronary reperfusion. To define molecular mechanisms, cultured adult and neonatal rat ventricular cardiomyocytes (ARVMs/NRVMs) were subjected to simulated I/R. Results: Induction of cardiomyocyte autophagy at reperfusion reduced infarct size 20.1% (±6.3%, n=23, p&lt;0.02 vs VC). This treatment was associated with improved systolic function (declines in fractional shortening: 19.8±3.7% VC; 18.7±2.1% TS; 8.5±1.7% TB, n=11, p&lt;0.01 vs VC). In NRVMs subjected to I/R injury, cell death was reduced 41% (±6%, n=12, p&lt;0.001 vs VC). Improvements correlated with increased autophagic flux measured by the marker LC3-II, particularly at the infarct border zone. Additional data suggested that autophagy rescues I/R injury through reduction of oxidative stress. ATG7 KO mice or NRVM depleted of ATG7 (RNAi) manifested significantly less cardioprotection. Conclusion: Direct induction of cardiomyocyte autophagy reduces infarct size and declines in contractile function. Autophagy rescues I/R injury in part through reduction of oxidative stress. Critically, this cardioprotection was observed when intervention occurred at the time of reperfusion, the clinically relevant context.

Cardiac Stem Cells for Myocardial Regeneration: They Are Not Alone.

Heart failure is the number one killer worldwide with ~50% of patients dying within 5 years of prognosis. The discovery of stem cells, which are capable of repairing the damaged portion of the heart, has created a field of cardiac regenerative medicine, which explores various types of stem cells, either autologous or endogenous, in the hope of finding the “holy grail” stem cell candidate to slow down and reverse the disease progression. However, there are many challenges that need to be overcome in the search of such a cell candidate. The ideal cells have to survive the harsh infarcted environment, retain their phenotype upon administration, and engraft and be activated to initiate repair and regeneration in vivo. Early bench and bedside experiments mostly focused on bone marrow-derived cells; however, heart regeneration requires multiple coordinations and interactions between various cell types and the extracellular matrix to form new cardiomyocytes and vasculature. There is an observed trend that when more than one cell is coadministered and cotransplanted into infarcted animal models the degree of regeneration is enhanced, when compared to single-cell administration. This review focuses on stem cell candidates, which have also been tested in human trials, and summarizes findings that explore the interactions between various stem cells in heart regenerative therapy.

METALLURGICAL ASPECTS RELATED TO CONTACT FATIGUE PHENOMENA IN STEELS FOR BACK-UP ROLLS

The need of even longer rolling sessions is driving the improvement of back up rolls in terms of wear resistance. This is also aimed to reduce costs. In this paper the effect of steel chemical composition on contact fatigue phenomena, bringing to the macroscopic damage named spalling is reported. Results show that the removal by grinding operations of damaged portion of rolls surface should be not sufficient to restore the initial performances of material. Experimental tests showed that a portion of material below the damaged one keeps memory of the last fatigue cycle, and has to be removed.

Preliminary Study on the Enhancement of Seismic Performance of Korea Hospital Buildings

Secure operation of hospitals during and right after earthquake is essential. Past lessons from earthquake damages have shown that most of the injured and the death occurred within 30 minutes after earthquake and the portion of nonstructural damage has become significant. However, hospital buildings in Korea have not prepared fully to address such rising issues. This paper is to study what type of damage patterns are related to hospital buildings and how to develop a preparedness plan to keep hospitals operational at all earthquakes if possible. This paper first reviews on past earthquake damages reported as critical to hospital buildings while classifying them into four groups: (1) structural element; (2) architectural-nostructural element; (3) medical equipments and contents; and (4) utility facility. Upon such classification, some detailed concerns can be specified under each group explicitly. Then a hierarchy for hospital building is also developed for the classified groups, which enables us to identify required things for the enhancement of seismic performance of hospital building that consists of heterogeneous elements. To upgrade the level of seismic performance for existing hospital buildings, the concept of performance-based approach can be adopted to address the heterogeneous problems in a systematic and stepwise manner. Finally a conceptual framework for the seismic risk assessment for hospital building is proposed toward the seismic enhancement of hospital buildings using performance-based approach.

Implantable amyloid hydrogels for promoting stem cell differentiation to neurons

We report a new class of amyloid-inspired peptide hydrogels that was designed and based on α-synuclein protein for which hydrogel formation is triggered by various stimuli, such as heating/cooling or changes in pH. The peptides resemble a cross-β-sheet-rich amyloid, and they assemble into a nanofibrous meshwork that mimics the natural extracellular matrix. Our design principle allows easy manipulation of the gelator sequence to exploit the desirable properties of amyloids for use in cell replacement therapies for neurodegenerative diseases. The amyloid hydrogels facilitate the attachment and neuronal differentiation of mesenchymal stem cells (MSCs) and assist in the delivery and engraftment of MSCs in the substantia nigra and caudate putamen of a Parkinsonian mouse model. A responsive, water-trapping biopolymer can fight neurodegenerative illnesses by promoting the growth and survival of implanted stem cells. Regenerating damaged portions of the nervous system with stem cells is a promising therapy for Alzheimer's and Parkinson's diseases, but ensuring cell viability in damaged brain tissue is challenging. Inspired by amyloid proteins that self-assemble into robust fibrils, Samir Maji from the Indian Institute of Technology in Mumbai, John Forsythe from Monash University in Melbourne and co-workers have developed peptide-based materials that turn into hydrogels on changing the pH or temperature. The hydrogels' nanofibrous, mesh-like structure and tunable stiffness proved favourable for cell replacement therapy. Experiments with Parkinsonian mouse models revealed that stem cells cultured on the hydrogels preferentially differentiated towards neurons and could be easily implanted thanks to the gels' ability to re-liquefy. Inspired by a popular self-assembled motif in proteins called amyloids, we have developed a series of hydrogels composed of amyloid nanofibrils. The gelation process could be induced via different stimuli, such as heating/cooling or change of pH. Human mesenchymal stem cells preferentially differentiate toward neurons when cultured on these hydrogels. Moreover, its shear thinning property facilitates transplantation of stem cells into the brain with minimally invasive surgery. We demonstrate here the utilization of injectable amyloid hydrogels, which promotes cell survival as well as neuronal differentiation in vivo.

Abstract 86: Compromised Sarcolemmal Membrane Repair Contributes to the Progression of Heart Failure

A conserved sarcolemmal membrane repair response exist to counteract membrane damage and restore membrane barrier function in order to maintain normal cellular homeostasis. This response can involve various mechanisms including activation of signaling pathways that trigger vesicular trafficking to the site of injury followed by vesicular fusion with the damaged portion of the membrane to patch the membrane disruption. Previous studies indicate that compromised repair capacity can exacerbate cardiac injury while increasing membrane repair capacity can reduce cardiac pathology. In our studies, membrane repair assays on cardiac and non-cardiac cell lines demonstrated that this process is dependent on activation of the phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) signaling axis through the downstream target Akt1. One mechanism found to increase membrane repair following PI3K/Akt1 activation is elevated exocytotic and endocytotic activity. Further studies indicate that the PI3K/Akt1 pathway is relevant to membrane repair in native hearts. Thick slices of myocardium from explanted human and mouse hearts were probed using multi-photon microscopy to determine the membrane repair capacity. These studies indicate decreased repair capacity in failing human myocardium as well as in mouse hearts following transaortic constriction (TAC). This membrane repair response requires PI3K/Akt1 signaling as genetically modified mice null for Akt1 show compromised sarcolemmal membrane repair. Additionally, PI3K or Akt1 inhibition prevents membrane resealing in non-failing human or mouse myocardium. The compromised membrane repair observed in failing human myocardium can be ameliorated by PI3K or Akt1 agonists. Treatment of TAC mice with multiple therapeutic compounds known to increase membrane repair capacity can minimize the development of structural and functional hallmarks of heart failure. Our results indicate that failing cardiomyocytes exhibit compromised membrane repair and that increased PI3K/Akt1 signaling can increase repair capacity thereby demonstrating potential as a heart failure treatment.

Are the cohesive zone models necessary for delamination analysis?

We develop a dual-purpose damage model (DPDM) that can simultaneously model intralayer damage (ply failure) and interlayer damage (delamination) as an alternative to conventional practices that models ply failure by continuum damage mechanics (CDM) and delamination by cohesive elements. From purely computational point of view, if successful, the proposed approach will significantly reduce computational cost by eliminating the need for having double nodes at ply interfaces. At the core, DPDM is based on the regularized continuum damage mechanics approach with vectorial representation of damage and ellipsoidal damage surface. Shear correction factors are introduced to match the mixed mode fracture toughness of an analytical cohesive zone model. A predictor–corrector local–nonlocal regularization scheme, which treats intralayer portion of damage as nonlocal and interlayer damage as local, is developed and verified. Two variants of the DPDM are studied: a single- and two-scale DPDM. For the two-scale DPDM, reduced-order-homogenization (ROH) framework is employed with matrix phase modeled by the DPDP while the inclusion phase modeled by the CDM. The proposed DPDM is verified on several multi-layer laminates with various ply orientations including double-cantilever beam (DCB), end-notch-flexure (ENF), mixed-mode-bending (MMB), and three-point-bending (TPB).

An investigation on low frequency fatigue damage of mooring lines applied in a semi-submersible platform

Assessing the fatigue life of mooring systems is important for deep water structures. In this paper, a comprehensive fatigue analysis is conducted on the mooring lines applied in a semi-submersible platform with special focus on the low frequency (LF) fatigue damage. Several influential factors, including water depth, wave spectral parameters, and riser system, are considered. Numerical simulation of a semi-submersible platform with the mooring/riser system is executed under different conditions, and the fatigue damage of mooring lines is assessed by using the time domain analysis method as a benchmark. The effects of these factors on the mooring line tension and the fatigue damage are investigated and discussed in detail. Research results indicate that the LF fatigue damage only accounts for a very small portion of the total damage, although the LF components dominate the global motion response and the mooring line tension of the semi-submersible platform. However, it is demonstrated that the LF fatigue damage is clearly affected by the influential factors. The increase in water depth and spectral peak periods, and the existence of risers can weaken the contribution of the LF components to the mooring line fatigue damage, while the fatigue damage due to the LF components increases with the increase of significant wave height.

Urban downburst vulnerability and damage assessment from a case study in Argentina

This paper presents a study of the damage pattern caused by a severe storm consisting of a downburst, a type of gustnado, and a tornado on Bell Ville, Argentina. Two damage surveys were conducted, one involving around 4000 questionnaires, which afforded both quantitative and qualitative insights about the damage on infrastructure, building components, and trees. Key findings include the identification of the most vulnerable urban elements which represented a significant portion of overall damage. Damage interdependencies among urban elements were also identified. The findings gained in this study help to characterize the vulnerability of this and similar cities for the most frequent intensity of downbursts, and along with some general recommendations which are also presented, they can inform local building codes, land-use regulations, and community development ordinances for cities facing this type of hazard in order to increase resilience.

Influence of cumulative damage on seismic response modification factors of elastic perfectly plastic oscillators

Based upon elastic perfectly plastic oscillators, this research investigates the influence of cumulative damage on seismic response modification factors. To take into account the cumulative damage due to hysteretic energy absorption, the Park–Ang damage index was adopted as the damage measure. A large number of iterative nonlinear response history analyses were conducted for the oscillators with periods and other features representative of conventional civil structures. Analysis results show that a significant portion of the total damage in a system reaching its damage limit state is due to hysteretic energy absorption. Consequently, the maximum tolerable ductility demand in the system under earthquake loading is lower than its ductility capacity determined under the monotonic loading condition. Moreover, the existing formulae for calculating response modification factors are shown to be inadequate to capture the effect of cumulative damage. A new method was developed for improved estimates of the response modification factors.

To the theory of acoustic scanning of pipelines with the damaged areas

The evolution of the pressure disturbances propagating in the tubular channel filled with liquid or gas and having a damaged portion in a sufficiently large gaps with low resistance. To this end, it adopted a mathematical model that takes into account the viscous friction and heat transfer in a thin layer of liquid (or gas) near the wall. On the basis of this model, dispersion equation for distribution processes and reflections from the damaged portion of harmonic waves. The dependence of the phase velocity, attenuation coefficient, as well as the reflection and transmission coefficients of the angular frequency and the physical properties of a liquid or gas. The results of calculations to illustrate the dynamics of pulse signals depending on the magnitude of damage, defined as the ratio of the gap area to the sectional area of the channel.