Predominant Mode Research Articles

Numerical Study on Flexible Pipe End Fitting Progressive Failure Behavior Based on Cohesive Zone Model

Flexible pipes are extensively used to connect seabed and floating production systems for the development of deep-water oil and gas. In the top connection area, end fitting (EF) is the connector between the flexible pipe and floating platform, as a critical component for structural failure. To address this issue, a combined numerical and experimental prediction method is proposed in this paper to investigate the failure behavior of flexible pipes EF considering tensile armor and epoxy resin debonding. In order to analyze the stress distribution of the tensile armor and the damage state of the bonding interface as the tensile load increases, a finite element model of the EF anchorage system is established based on the cohesive zone model (CZM). Additionally, the effects of the epoxy resin shear strength (ss) and the steel wire yield strength (ys) on the structural load-bearing capacity are discussed in detail. The results indicate that wire strength and interface bonding have a substantial effect on the anchorage system’s failure behavior, and the low-strength wire anchorage system has a three-stage failure behavior with wire yielding as the predominant failure mode, while the high-strength wire anchorage system has a two-stage failure behavior with interface debonding as the predominant failure mode.

Mobility patterns in healthcare centres. Case Study: La Paz University Hospital (Madrid, Spain)

The COVID-19 pandemic has highlighted the need to ensure good accessibility to healthcare centres, which first requires to study mobility patterns. This work presents a new method based on a dual vision of healthcare centres: as a public facility and as a workplace. This method is applied to the case study of La Paz University Hospital, one of the most important Spanish hospitals. Through a survey campaign using different collection methods, the mobility patterns of patients and staff were studied, obtaining a total of 2,160 valid responses. According to the results, the private vehicle is the predominant mode with a modal share of more than 50%, aggravating the parking problems. Finally, this study has analysed behavioural changes due to the COVID-19 pandemic, which have led to a decrease in the use of public transport, with commuters now opting for active modes or the private vehicle.

Disease Burden of Hepatitis B Infection and Section Vaccination Trends in Healthcare Workers: A Prospective Cohort Study

Introduction: Hepatitis B Virus (HBV) infection is an important occupational hazard for Healthcare Workers (HCWs), with an approximately four-fold increased risk of acquiring this infection compared to the normal population. The horizontal mode of transmission is the predominant mode among HCWs. Additionally, vaccination trends among HCWs have been disappointing, with paramedics reported to have a higher risk of HBV transmission and receiving HBV vaccination less often than doctors. Aim: To determine the burden of hepatitis B infection and vaccination trends among HCWs. Materials and Methods: This cross-sectional study was conducted at Pandit Bhagwat Dayal Sharma PGIMS, Rohtak Haryana, India, from March 2019 to January 2020, enrolling 250 HCWs. The study included 80 junior residents, 17 house surgeons, 123 nursing staff, 18 Laboratory Technicians (LTs), and 12 Operation Theatre Assistants (OTAs). The subjects were divided into two groups: medical workers (Group-1; House Surgeons and Junior Residents) and paramedical workers (Group-2; Nursing staff, LTs, OTAs). The sample size was calculated using Probability Proportion to Size (PPS) of HCWs. Descriptive statistics were performed. Results: None of the subjects tested positive for Hepatitis B surface Antigen (HBsAg) during the study period. A total of 196 (78.4%) subjects were vaccinated, while 54 (21.6%) subjects remained Non-Vaccinated (NV). Out of the 196 vaccinated subjects, 140 (71.4%) were Completely Vaccinated (CV), and 56 (28.6%) were Incompletely Vaccinated (IV). The vaccination rate was highest among junior residents (95%) and lowest among LTs and OTAs (50%). Among the 80 junior residents, 76 (95%) were vaccinated, and 4 (5%) were NV. Among the 123 nursing staff, 89 (72.3%) were vaccinated, and 34 (27.7%) were CV, 9 (50%) were NV and 3 were in category of IV. Among the 18 LTs, 6 (33.3%) were CV, and 9 (50%) were NV. None of the 12 OTAs were CV, with 6 (50%) being NV. Conclusion: HCWs are at a potential risk of contracting HBV infection as an occupational hazard. There is need to strengthen efforts towards vaccination and prevention of HBV infection.

Electroencephalography microstates imbalance across the spectrum of early psychosis, autism, and mood disorders.

Electroencephalography (EEG) microstates translate resting-state temporal dynamics of neuronal networks throughout the brain and could constitute possible markers of psychiatric disorders. We tested the hypothesis of an increased imbalance between a predominant self-referential mode (microstate C) and a decreased attentional mode (microstate D) in psychosis, mood, and autism spectrum disorders. We retrospectively included 135 subjects from an early psychosis outpatient unit, with available eyes-closed resting-state 19 electrodes EEG. Individual-level then group-level modified K-means clustering in controls provided four microstate maps that were then backfitted to all groups. Differences between microstate parameters (occurrence, coverage, and mean duration) were computed between controls and each group, and between disease groups. Microstate class D parameters were systematically decreased in disease groups compared with controls, with an effect size increasing along the psychosis spectrum, but also in autism. There was no difference in class C. C/D ratios of mean duration were increased only in SCZ compared with controls. The decrease in microstate class D may be a marker of stage of psychosis, but it is not specific to it and may rather reflect a shared dimension along the schizophrenia-autism spectrum. C/D microstate imbalance may be more specific to schizophrenia.

Microshear bond strength of resin cement to a zirconia-reinforced lithium silicate glass ceramic using different surface treatments

Background: The purpose of this study was to evaluate the effect of different surface treatments on the microshear bond strength (μSBS) of resin cement to zirconia-reinforced lithium silicate ceramic and to compare it with lithium disilicate ceramic. Materials and Methods: In this in vitro study, 80 specimens containing two glass ceramics of IPS e.max press and VITA SUPRINITY were prepared and categorized into four groups according to the surface treatments (n = 10) as Group 1 (C): no treatment (control); Group 2 (HF): etching with 9% hydrofluoric acid (HF) for 90 s followed by silane application; Group 3 (SPH): sandblasting with Al2O3 particles (50 μm), etching with 35% phosphoric acid for 40 s followed by application of silane and adhesive (Clearfil liner bond F); and Group 4 (SB): sandblasting with Al2O3 followed by silanization. Then, a resin cement (Panavia F2) was applied to the prepared ceramic surfaces. All samples were subjected to thermal aging (5000 cycles, 5–55). The μSBS test was evaluated and failure modes were recorded. Data were analyzed using the Shapiro–Wilk, two-way analysis of variance and Tukey's Honest Significant Difference post hoc tests (P < 0.05). Results: IPS e.max press samples revealed significantly higher μSBS values compared to VITA SUPRINITY (P < 0.001), in whole surface treatments. The HF group showed the highest μSBS value, followed by the SPH and SB groups, respectively (P < 0.001). Adhesive failure was recorded as a predominant failure mode. Conclusion: The adhesion performance of IPS e.max press was significantly higher than VITA SUPRINITY. The common surface treatment protocol including HF application followed by silanization was the most effective surface treatment for both glass ceramics.

Old Dog, New Tricks: A Review of Identifying and Addressing Youth Cannabis Vaping in the Pediatric Clinical Setting

Cannabis vaping has emerged as a predominant mode of cannabis use among United States (US) adolescents and young adults (AYA) primarily due to the popularity of modifiable designs of vaping devices coupled with changes in cannabis policies and increased availability of cannabinoid products. New methods for cannabis vaping by e-liquid/oil vaping, dry plant vaping, and cannabis concentrate vaping (ie, dabbing) have had high uptake among American youth with unclear long-term health implications. Issues with contamination, mislabeling, and expansion of the vaped cannabis market to include not only delta-9-tetrahydrocannabinol (delta-9-THC) and cannabidiol (CBD) but also delta-9-THC analogs (eg, delta-8 and delta-10) sold as hemp-derived "legal highs" further complicated this healthcare space. Recent research suggests that cannabis/THC vaping carries distinct and overlapping risks when compared to cannabis smoking and may be associated with greater risk for acute lung injuries, seizures, and acute psychiatric symptoms. Primary care clinicians providing care for AYA are in an ideal position to identify cannabis misuse and intervene early to address cannabis vaping. To improve public health outcomes, a need exists for pediatric clinicians to be educated about different ways/methods that youth are vaping cannabinoid products and associated risks related to cannabinoid vaping. Further, pediatric clinicians need to be trained how to effectively screen for and discuss cannabis vaping with their youth patients. In the current article, we present a clinically focused review of cannabis vaping among young people with 3 main aims to: (1) identify and describe the cannabis vaping products commonly used by American youth; (2) review the health correlates of youth cannabis vaping; and (3) discuss clinical considerations related to identifying and treating youth who vape cannabis.

An experimental study of friction stir welding parameters effect on joint properties of aluminium alloy and copper plate

Joining dissimilar metals like copper and aluminium is a complex area of research for the manufacturing industry. To effectively join the AA7075 with copper plates, an experimental investigation on friction stir welding was carried out. A straight cylindrical pin profile tool of H13 tool steel was chosen for this study. On the advancing direction, the AA7075 plates were fixed under the condition of zero tool offset. The tool was positioned at a 2° tilt angle for the entire experiment. Tensile test, microhardness test, SEM and EDS analysis were completed to investigate the effectiveness of the process parameters (tool traverse and rotational speed) in combination with a modified set-up on the microstructure, tensile strength and microhardness of the joint. Fractography was conducted on fractured specimens to identify the mode of failure. Complex microstructures of swirl and vortex-type material flow patterns were created in the stir zone. As a result of SEM analysis, one of the samples (S5) had finer grains at intermediate heat input, which produced excellent microhardness and tensile strength. Fractography identified ductile failure as the predominant mode of failure in the joints. The results of this study include an ultimate tensile strength value of 221.091 MPa with a joint efficiency of 95.05%, yield strength of 159.035 MPa, maximum elongation of 9.335% and a microhardness value of 271 HV for specimen welded at a traverse speed of 60 mm min−1 and a rotational speed of 1400 rpm.

Metaldehyde Transport Processes in a Water Abstraction Catchment in Essex, Southeast England

This paper addresses the issue of pesticide loss from agriculture and its impact on the aquatic environment. Specifically, this study assesses the transport of the relatively water-soluble polar molluscicide compound metaldehyde in a small (14 km2) water abstraction catchment in Essex, southeast England during a 14-month period (January 2019–February 2020). A rise in metaldehyde concentrations was observed at all monitoring points, to varying extents, in the months of seasonal metaldehyde applications. The highest increases in metaldehyde concentrations (up to 0.05 µg L–1) across the catchment were observed in the autumn months and in December. These findings reinforce the mobile nature of the pesticide, with surface and field drain runoff likely to be the predominant mode of transfer to surface waters. The scale of individual sources of metaldehyde influx to the Ardleigh surface storage reservoir in the catchment showed that the highest contribution to the total flux to the reservoir was from water transferred from the adjacent River Colne catchment. Atmospheric deposition of metaldehyde followed a similar seasonal pattern to that observed in metaldehyde levels in surface water and field drain runoff, and in certain months accounted for a higher input than influx from surface runoff (May, August–October 2019). Monthly values of metaldehyde mass in the reservoir ranged from 27.7 to 47.4 g. An increase in mass was associated with elevated levels of flux from individual sources. Relatively stable levels of metaldehyde total mass in the reservoir are probably due to the aqueous solubility and decreased degradation rates of metaldehyde in the aquatic environment.

Highlighting Pedestrian Equity Considerations Using Walkability Space Syntax: A Case from Suburb in India

Increasing urbanization has led to uncontrolled growth along the periphery of urban areas, particularly in developing countries. This has led to the formation of suburban areas around the metropolis, which are characterized by low-density neighborhood with the places of activities like education, and work, usually far off from one another. Walking is the predominant mode of transport across the world, but the facilities for pedestrians, while planning and implementation, are usually overlooked. Hitherto, ample amount of literature has been found to be centric to the pedestrian analysis in core city under different purviews, but only some studies highlight pedestrian inequity in suburban diorama. To highlight these pedestrian issues, a study was conducted in Kajlikheda, a suburb area of Bhopal, which is the capital city of Madhya Pradesh, a central state of India. The paper highlights the pedestrian equity concern through Walkability Space Syntax (WSS). WSS of street integration and pedestrian choice analysis is used for understanding the walking pattern in a neighborhood. A reconnaissance survey was conducted to find out the available pedestrian infrastructure and facilities, post which absence of these facilities was observed. To establish the share of pedestrians in traffic and reinforce the findings, a Traffic Volume Count was conducted, and pedestrian share was found to be substantial. In cognizance to the laid standards, volume to capacity ratio was calculated for automobiles and pedestrians for quantifying the Level of Service (LoS) for both the modes. Through statistical analysis, the paper attempts to express the need to take adequate consideration to provide better pedestrian facilities, which can be generalized in various suburban scenarios across the globe. The research also brings a new dimension to the pedestrian equity studies by integrating concepts of space syntax to answer the modality.

Sedimentological Study of Alluvial Deposits on the Congolese Coast: Highlighting the Erosive Character of the Holocene Wet Climatic Phases

A granulometric, mineralogical, morphoscopic and exoscopic study and Rock-Eval analysis carried out on samples taken in the Loango Bay and at Kivesso on the Congolese coast have made it possible to highlight the highly erosive character of the well-documented wet phases ca 9000 - 3000 years B.P. and ca 320 B.P. in the sub-region. Supported by carbon-14 dating, total organic carbon analyses highlight two major phases of peat deposit emplacement. The first, ca. 7000 years B.P., corresponds to the beginning of the deposition of the yellow formation in the entire Loango Bay; the second, ca. 320 years B.P., is contemporary with the deposition of peat in the Kivesso sector. The granulometric analysis of the sediments shows that they are essentially sandy-clay and very poor in silt, alternating with beds of silty clay sometimes rich in organic matter. These sands have a predominant mode of 0.200 mm and an average varying between 0.150 and 0.300 mm. They constitute the flood phase of the carrier current. They are associated with a population of mode 0.125 mm sometimes 0.050 mm with an average varying between 0.100 mm and 0.126 mm which corresponds to the settling phase. Morphoscopic examination showed several varieties of quartz that argue for a source of supply close to the depositional sites.

Role of metal complexes in inhibition of cancer growth factors

Cancer is characterized by uncontrolled cell growth, representing a hallmark feature marked by sustained proliferation. This heightened proliferative capacity is primarily driven by the influence of growth factors. Scientific evidence suggests that growth factors play a crucial role in augmenting the transcription of specific proto-oncogenes, such as myc and fos. In the context of cancer development, these growth factors can be either produced by the cancer cells themselves or induce normal cells to release them through intricate signaling mechanisms. The functional diversity of growth factors encompasses various actions, but their predominant mode of operation is through the tyrosine kinase receptor pathway. Tyrosine kinase receptors, comprising integral membrane complexes with intrinsic kinase activity in their cytoplasmic domain, play a pivotal role in transducing signals initiated by the binding of specific growth factors (ligands). This binding event triggers the activation of the kinase function within the receptor, resulting in the phosphorylation of downstream targets on tyrosine and serine residues. Subsequently, this phosphorylation event recruits additional molecules into signaling cascades, amplifying the cellular response. Transition metals, such as Copper, Zinc, and Cobalt, integral to biological systems, play pivotal roles in normal physiological functions. However, dysregulation of these essential metals has been implicated in the pathogenesis of various disorders, including cancer. The narrative unfolds by elucidating the critical role of growth factors in cancer cell proliferation. Key growth factors, such as Transforming Growth Factor-β, Tumour Necrosis Factor-α and Insulin-like Growth Factors, are explored within the context of cancer progression. The intricate signaling pathways, particularly the Tyrosine Kinase Receptor pathway, are examined to understand how metal complexes may disrupt these pathways, impeding uncontrolled cell growth. Furthermore, this review provides an in-depth examination of medicinal inorganic chemistry, emphasizing the ability of transition metal complexes to form charged ions and induce hydrolysis reactions. The nuanced discussion underscores the necessity for precise dosages of metal-containing drugs to avoid undesirable toxicity, acknowledging the delicate balance required for optimal therapeutic responses. This comprehensive review delves into metal complexes of Cobalt, Copper, Zinc, and metal nanoparticles as promising inhibitors of cancer growth factors. By explicating the intricate interplay between metal complexes and growth factor pathways, this article contributes to the ongoing scientific exploration of novel and effective anticancer strategies.

Effect of different surface treatments on resin-matrix CAD/CAM ceramics bonding to dentin: in vitro study

BackgroundEvaluating the effect of different surface treatment methods on the micro-tensile bond strength (µTBS) of two different resin-matrix computer-aided design/computer-aided manufacturing (CAD/CAM) ceramics (RMCs).MethodsA standardized inlay preparations were performed on 100 intact maxillary premolars. According to the type of the restorative material, the teeth were randomly divided into two equally sized groups (n = 50): (polymer-infiltrated ceramic (Vita Enamic) and resin-based composites (Lava Ultimate)). The inlays were fabricated using CAD/CAM technology. In each group, the specimens were randomly assigned to five subgroups (n = 10) according to the surface treatment method: group 1 used was the control group (no surface treatment); group 2, was treated with air abrasion with 50 μm Al2O3 (A) and universal adhesive (UA); group 3, was treated with air abrasion with 50 μm Al2O3 (A) and silane coupling agent (S); group 4, was treated with hydrofluoric acid (HF) and universal adhesive (UA) and group 5, was treated with Hydrofluoric acid (HF) + silane coupling agent (S). The inlays were then cemented to their respective preparations using dual-cure self-adhesive resin cement (RelyX U200, 3 M ESPE) according to the manufacturer’s instructions. The µTBS test was conducted in all groups, and stereomicroscope and scanning electron microscope were used to inspect the failure mode. The data were statistically analyzed using a two-way analysis of variance (ANOVA) and Tukey’s post-hoc multiple comparison tests at a significance level of p < 0.05.ResultsSurface treatments significantly increased the µTBS of the materials compared to the control group (p < 0.05). For CAD/CAM RBCs, the µTBS value highest in group 2 whereas, for PICN, the µTBS value was highest in group 3. Cohesive failure of CAD/CAM restorative material was the most predominant mode of failure in all treated groups, whereas adhesive failure at restoration-cement interface was the most predominant failure mode in the control group.ConclusionSurface treatments increase the µTBS of resin-matrix CAD/CAM ceramics to tooth structure. Air abrasion followed by universal adhesive and hydrofluoric acid followed by silane application appears to be the best strategies for optimizing the bond strength of CAD/CAM RBCs and PICN respectively.

A Position Statement on Mpox as a Sexually Transmitted Disease.

The global outbreak of mpox virus constituted an international public health emergency. Reports have highlighted (1) a temporal association between sexual activity and mpox, (2) an association between specific sexual practices and location of lesion development, (3) a high frequency of sexual practices conferring risk for other sexually transmitted infections among cases of mpox, (4) that mpox virus can be isolated from sexual fluids, (4) that isolated virus is infectious, and (5) a high frequency of anogenital lesions prior to disease dissemination suggesting direct inoculation during sexual activities. Finally, a growing body of evidence suggests that sexual transmission is the predominant mode of transmission for mpox virus. We therefore conclude that mpox is a sexually transmitted disease. Labeling it as such will help focus public health interventions, such as vaccinations, testing, and treatment, as well as facilitate focused awareness and education programs toward behavioral modifications to reduce exposures.

Experimental study on tensile deformation behaviors under room and elevated temperatures induced by microstructure inhomogeneity of ZK60 Mg with a longitudinal weld

The tensile tests of the extruded ZK60 Mg containing a longitudinal weld seam were carried out at room and elevated temperatures, and the effects of induced microstructure inhomogeneity on tensile deformation behavior was clarified. The results show that the deformation mode, dynamic recrystallization (DRX), texture evolution and mechanical properties are strongly affected by the longitudinal weld seam, temperature, and loading direction. The room temperature (RT) deformation of welding zone is controlled by the dislocation slips with the association of some twins, while twinning plays significant roles in the accommodation of c-axis strain of the coarse grains on matrix zone. The deformation at RT stretched along extrusion direction (ED) and transverse direction (TD) are controlled by basal slip/twinning and basal slip/prismatic slip/twinning, respectively. During high temperature tension, the dislocation cross slip of pyramidal slip is activated, and grain boundary sliding occurred in welding zone, leading to the superplastic behavior. With the increase of tensile temperature, the predominant DRX mode is transformed from continuous DRX to discontinuous DRX. Moreover, the basal poles of the grains spread from TD towards ED with the decrease of maximum pole intensity when stretched along ED, while non-basal textures are transformed to 〈10–10〉 fiber texture when stretched along TD. The slip-dominated flow is seen during RT tension along ED, while twinning becomes predominant during RT tension along TD. The fine grain structure causes the superior RT tensile properties along ED of welding zone with ultimate tensile strength of 315 MPa and elongation to failure of 13.8%. With the increase of tensile temperature, the slipping-dominated deformation is transformed into twinning-dominated, causing the decrease of strength and increase of elongation.

A fast, efficient, and scalable method for purifying recombinant SARS-CoV-2 spike protein

Recombinant SARS-CoV-2 trimeric spike protein produced by mammalian cell culture is a potential candidate for a COVID-19 vaccine. However, this protein is much larger than most typical biopharmaceutical proteins and its large-scale manufacture is therefore challenging. Particularly, its purification using resin-based chromatography is difficult as the diffusive transport of this protein to and from its binding site within the pores of the stationary phase particles is slow. Therefore, very low flow rates need to be used during binding and elution, and this slows down the purification process. Also, due to its large size, the binding capacity of this protein on resin-based media is low. Membrane chromatography is an efficient and scalable technique for purifying biopharmaceuticals. The predominant mode of solute transport in a membrane is convective and hence it is considered better than resin-based chromatography for purifying large proteins. In this paper, we propose a membrane chromatography-based purification method for fast and scalable manufacture of recombinant SARS-CoV-2 trimeric spike protein. A combination of cation exchange z2 laterally-fed membrane chromatography and size exclusion chromatography was found to be suitable for obtaining a homogeneous spike protein sample from mammalian cell culture supernatant. The proposed method is both fast and scalable and could be explored as a method for manufacturing vaccine grade spike protein.

Predictive significance and diagnostic accuracy of plasma fibrinogen levels for coronary stenting outcomes

Objective: The advancement in percutaneous transluminal coronary angioplasty (PTCA) has led to it becoming the predominant mode of revascularization. Post PTCA adverse events in the form of stent thrombosis, recurrent ischemia, unplanned revascularization, recurrent hospitalization etc. result in morbidity as well as mortality. Biomarkers predicting such outcomes can be useful in initiating more aggressive medical therapy and greater modification of risk factors. This study was undertaken to study the predictive significance of periprocedural plasma fibrinogen levels for coronary stenting outcomes. Methods: 80 patients diagnosed as either chronic stable angina (CSA), unstable angina (UA), Non ST Elevation Myocardial Infarction (NSTEMI) or late presentation ST Elevation Myocardial Infarction (STEMI) undergoing planned PTCA were included in study. Patients were evaluated for clinical history, electrocardiogram (ECG), two dimensional echocardiography (2D-echo) and cardiac biomarkers (Creatinine Phosphokinase-MB isomer (CK-MB) and Troponin I). Serum fibrinogen level was measured 24 hours prior to PTCA along with routine pre-operative investigations; and also 24 hours after coronary stenting. Patients were followed for six months. Outcome measure was taken to be freedom from cardiac related adverse events, including rehospitalization, unplanned repeat revascularization, definite stent thrombosis, transient ischemic attack, stroke and all-cause mortality. Results: Fibrinogen level ≥393 mg/dL, 24 hours prior to percutaneous transluminal coronary angioplasty, was associated with higher major adverse cardiac and cerebrovascular events (MACCE) rates (60%) as compared to those with fibrinogen level &amp;lt;393 mg/dL (3.6%). Fibrinogen level ≥427 mg/dL 24 hours after percutaneous transluminal coronary angioplasty, was associated with higher major adverse cardiac and cerebrovascular events rates (65%) as compared to those with fibrinogen level &amp;lt;427 mg/dL (6.7%). Conclusion: The current study demonstrates that higher baseline and post procedural fibrinogen, is an independent predictor of 6 months major adverse cardiac and cerebrovascular events after elective percutaneous coronary intervention. Key words: Coronary stent outcomes, major adverse cardiac and cerebrovascular events, plasma fibrinogen, stent diameter

Mixed-mode I + II fracture characterisation of a honeycomb/carbon-epoxy sandwich panel using the asymmetric single-leg bending test

The Asymmetric Single-Leg Bending (ASLB) test was employed to obtain the fracture energy of a honeycomb/carbon-epoxy sandwich panel under mixed-mode I + II loading. A data reduction method lying on beam theory, specimen compliance and equivalent crack length concepts was employed to get the experimental Resistance-curve (R-curve), which allows determination of the mixed-mode fracture energy. Numerical analysis including cohesive zone modelling was used for validation and as a suitable partition method useful to estimate the mode ratio. In view of the observed non-linear behaviour, a mixed-mode I + II trapezoidal cohesive zone model and the quadratic energetic criterion were considered in the simulations. Overall, it can be concluded that the ASLB test is appropriate for mixed-mode I + II fracture characterisation of sandwich panels under predominant mode I.

MANAGEMENT OF COMPLICATED TRAUMA BY LIMB RECONSTRUCTION SYSTEM (MONO-LATERAL EXTERNAL FIXATOR) IN LOWER EXTREMITY

Introduction: High velocity trauma is the cause of maximum number of fatality in the younger age group worldwide. In the field of trauma surgery open fractures of the leg remain with the higher complication rate. Treatment options include wound debridement reduction and immobilization with cast, open reduction and plate fixation, external fixation, and IM nailing. Limb reconstruction system (LRS) is a unilateral rail system which consists of Schanz pins, rail rods, and sliding clamps. LRS was considered as definitive management for open fractures. LRS with its modular attachments, it is specifically designed to enable the surgeon to perform simple and effective surgery as it offers rigid fixation of fracture fragments, allows early weight bearing, and reduces the economic burden. Aim: The aim of the study was to determine the efficacy of mono-lateral external fixator LRS for management of the lower extremity long bone fracture (tibia/femur). Methods: A prospective study was carried out where 26 cases of lower extremity trauma (complicated) managed by LRS over a period of 5–6 months. The patients ranged from age 13 years to 67 years. Majority were male and predominant mode of injury was road side accidents. Majority of case were exposed to multiple the surgeries before LRS application. Most of the cases are of infection non-union. All the patients were treated at our hospital. These surgeries were done from June, 2005 to 2007. Any bone fragments that were protruding out we recovered with sterile dressing. The patient were taken to the operating room and treated by pulsed lavage and debridement the wound and splints. In patients, whose bone was exposed, as the wound condition improved the patients were planned for flap rotation. Assessment of quality of regenerate was done by plain radiography and clinical assessment at every follow-up. Final assessment for bone results and functional results was done using Association of the study and application of the method of Ilizarov (ASAMI) score. Results: Among 26 patients, bony results as per ASAMI score were excellent in 73.07% (n=19), good in 19.23% (n=5), fair in 3.84% (n=1), and poor in 3.84% (n=1). Functional results were excellent in 84.7% (n=22), good in 11.5% (n=3), and fair in 3.8% (n=1). All the 26 cases of lower extremity fracture were kept on LRS external fixator for a period of 5–6 months on an average depending on the rate of union, after which the fixator was removed. For 2 patients nailing was done after LRS frame removal. Average time for frame removal was 28 weeks. In most cases union was complete by 7–8 months, the least being 5 months for a tibia shaft fracture. The average hospital stay for the patients was 7 days and as compared to multi staged surgery financial burden was reduced by 40%. The average time of return to work for the patients was 3 weeks. Conclusion: Overall LRS proved to be an effective modality of treatment in cases of the lower extremity fracture with bone loss as definite modality of treatment for damage control as well as for achieving union and lengthening/transportation, deformity correction simultaneously, with the advantage of simple surgical technique, ease of application, minimal invasive, strong fixation, high patient compliance, early weight bearing, easy wound management, and the lower rate of complication.

Enhancing the high-temperature creep properties of Mo alloys via nanosized La2O3 particle addition

Molybdenum (Mo) alloys with different La 2 O 3 particle additions (0.6, 0.9, 1.5 wt.%) were prepared by powder metallurgy to investigate the effect of La 2 O 3 particles on microstructural evolution and creep behavior of the alloy. Pure Mo, annealed at 1500 °C for 1 h, presented a fully recrystallized microstructure characterized by equiaxed grains. The alloys doped with La 2 O 3 particles (Mo-La 2 O 3 alloys), on the other hand, exhibited fibrous grains elongated in the rolling direction of the plate. In contrast to the shape of the grains, the average grain size of the alloys was found to be insensitive to the addition of La 2 O 3 particles. Nanosized La 2 O 3 particles with diameters ranging from 65 nm to 75 nm were distributed within the grain interior. Tensile creep tests showed that dislocation creep was the predominant deformation mode at intermediate creep rate (10 −7 s −1 -10 −4 s −1 ) in the present alloys. The creep stress exponent and activation energy were found to decrease with increasing temperature, particularly within the low creep rate regime (<10 −7 s −1 ). The Mo-La 2 O 3 alloys exhibited remarkably greater apparent stress exponent and activation energy than pure Mo. A creep constitutive model based on the interaction between particles and dislocations was utilized to rationalize the nanoparticle-improved creep behavior. It was demonstrated that low relaxed efficiency of dislocation line energy, which is responsible for an enhanced climb resistance of dislocations, is the major creep strengthening mechanism in the Mo-La 2 O 3 alloys. In addition, the area reduction and creep fracture mode of the Mo-La 2 O 3 alloys were found to be a function of the creep rate and temperature, which can be explained by the effect of the two parameters on the creep and fracture mechanisms.

Multiscale analysis of interior cracking behavior of Ni-based superalloy fabricated by selective laser melting under very-high-cycle-fatigue at high-temperature

The fatigue test at high-temperature of selective laser melting Ni-based superalloy was performed to reveal the mechanism of interior cracking behavior by multiple analysis methods in the very-high-cycle-fatigue regime. Due to the inhibition effect of oxide layer, the interior multi-defects assisted facetted cracking becomes a significant failure mode. Large grain deformation mainly occurs on the fracture surface, and slip systems with high Schmid factor are activated by high-temperature. The precipitates in the matrix hinder the dislocation movement, resulting in dislocation accumulation and stress concentration increase, which makes it easier for microcracks initiation. The initiated microcracks with crack deflection caused by high angle grain boundaries propagate transgranularly to form a nearly circular region and undergo fast unstable growth, eventually leading to fracture. • The microcracks propagate transgranularly along the maximum shear stress plane. • {111}<112> slip system with high Schmid factor is activated by high-temperature. • Interior multi-defects assisted facetted cracking is the predominant failure mode.