Compliance Method Research Articles

Remarkably high fracture toughness of HfNbTaTiZr refractory high-entropy alloy

• The fracture behavior of the Hfnbtatizr refractory HEA was investigated. • The HEA exhibits a remarkably high fracture toughness of K JIC = 211 MPa•m 1/2 . • Fully-ductile fracture mode with the formation of kink bands was observed. • The excellent damage-tolerance plus high strengths in a wide temperature range endow this HEA a promising structural material. High-entropy alloys (HEAs) with face-centered cubic (FCC) phase such as CoCrFeMnNi or CoCrNi generally exhibit ultra-high fracture toughness but relatively low strength. In contrast, body-centered cubic (BCC) HEAs often display higher strengths, but the few reports on fracture toughness measurement demonstrate low toughness values. Here we show that the BCC HfNbTaTiZr refractory HEA, which possesses a combination of high strength, good tensile ductility and excellent high-temperature properties, also exhibits a remarkably high fracture toughness. By using the "single specimen" compliance method for J -integral measurement according to the ASTM E1820–17 standard, its fracture toughness K JIC was experimentally determined to be 210 MPa m 1/2 , which renders this HEA among the toughest metallic materials. The excellent damage tolerance makes the HEA promising for applications as high-temperature structural materials such as in aerospace field.

Fracture toughness of High-Manganese steels with TWIP/TRIP effects

Three high-manganese steels with different carbon contents were investigated in this work, aiming to explore their elastoplastic fracture toughness, fracture micro-mechanisms and microstructural features. J-R curves were obtained according to ASTM E1820-20 by testing C(T) specimens, applying the unloading compliance method to measure crack extension. The TWIP effect (mechanical twinning + dislocation gliding) developed in Steel A and Steel B with carbon contents of 0.84 wt% and 0.54 wt% respectively. On the other hand, Steel C (carbon content of 0.28 wt%), showed strain-induced γFCC → εHCP transformation associated with the TRIP effect. The three steels presented smooth load (P) vs load-line displacement (v) records; i.e., no instability was observed, which allowed the characterization of fracture toughness by means of J-R curves. Fully dimpled fracture surfaces were observed in Steel A and Steel B, whilst Steel C showed small cleavage facets in some sectors that had not indication in the P vs v records. Best performance in terms of fracture behavior was obtained in Steel B and the poorest in Steel C. In addition to the above, the microstructural analysis of the stable crack growth zones in the fractured specimens allowed the identification of several characteristics.

Fatigue crack propagation of differently oriented octet-truss lattices

The influence of orientation on octet-truss lattice static properties has been extensively studied. Fatigue failure is one of the main forms of structural failure of lattices. The fatigue properties of lattice structures, such as crack growth direction and crack growth rate, depend on orientation. Hence, it is important to explore the orientation effects on octet-truss lattice fatigue. Differently oriented octet-truss lattices in this research were additively manufactured into compact tension specimen geometry using photopolymer. From the experiment, the fatigue crack paths for differently oriented lattices were observed and compared with each other. The compliance method described in ASTM E647 was used to calculate the fatigue crack growth rates of lattices in different orientations. It is found from experiment that orientation-ZX lattices have the greatest resistance to fatigue crack propagation. Analytical formulae to predict the lattice fatigue life in different orientations were derived by simplifying individual lattice struts as pin-jointed bars. These findings can help us understand the orientation dependence of lattice fatigue failure.

Inventory Routing for Ammonia Supply in German Ports

Following the International Maritime Organization (IMO), in order to safeguard the realization of the Paris Agreement on climate protection, greenhouse gas (GHG) emissions have to be reduced by 50% by the year 2050. This objective shall be reached by decarbonization of maritime traffic, which is why ship operators currently increasingly search for alternative fuels. Moreover, since the start of the Ukrainian war in February 2022, this issue of alternative fuels has gained central importance in political agendas. A promising candidate for clean shipping that meets the IMO goals is ammonia since it is a carbon-free fuel. Ammonia (NH3) shows good advantages in handling and storage, and it ensures long sea voyages without any significant loss in cargo space for a reasonable price. Hence, ammonia has the potential to improve the environmental footprint of global shipping enormously. Induced by the introduction of stricter regulations in the so-called emission control areas (ECAs) in Northern Europe in 2015 as well as the renewed global sulfur cap, which entered into force in 2020, ship operators had to decide between different compliance methods, among which the most popular solutions are related to the use of expensive low-sulfur fuel oils, newbuilds and retrofits for the usage of liquefied natural gas (LNG) or the installation of scrubber technology. A change to ammonia as a marine alternative fuel represents an additional novel future option, but the successful implementation depends on the availability of NH3 in the ports, i.e., on the installation of the maritime NH3 infrastructure. Currently, the single German NH3 terminal with maritime access is located in Brunsbüttel, the western entrance to Kiel Canal. The distribution of NH3 from the existing NH3 hub to other German ports can be analyzed by the mathematical model of an inventory routing problem (IRP) that is usually solved by combinatorial optimization methods. This paper investigates the interrelated research questions, how the distribution of marine NH3 fuel can be modeled as an IRP, which distribution mode is the most economic one for the German ports and which modal mix for the NH3 supply leads to the greenest distribution. The results of this paper are empirically validated by data that were collected in several EU projects on sustainable supply chain management and green logistics. The paper includes a special section that is dedicated to the discussion of the economic turbulences related to the Ukrainian war together with their implications on maritime shipping.

Metered Boot: Trusted Framework for Application Usage Rights Management in Virtualized Ecosystems

The adoption of virtualization and cloud computing technologies have revolutionized how services and applications can be developed, deployed, and operated to achieve better elasticity, flexibility, and scalability. Multiple stakeholders can be involved for providing online services; each of them plays one or more roles (i.e., service operator, application vendor, and infrastructure provider) to create a customized operating model based on the business requirements. The operating model changes from one business to another, and it may even change at different stages of the same business. A trusted relationship among stakeholders for secure information exchange is the key to enable such flexibility. However, traditional usage compliance methods (e.g., in-person audit, dynamic licensing, and subscription) lack explicit trust among involved parties and the flexibility and scalability to support dynamic sizing of services and applications with low overhead. In this work, we argue the need for a new trust framework to manage application usage rights and propose Metered Boot to provide trusted, capacity/usage-based usage rights management for services and applications deployed in virtualized environments. Metered Boot decouples application workload instantiation for service operators, usage rights governance for application vendors, and resource provisioning for infrastructure providers. We leverage cryptoprocessors (e.g., Trusted Platform Module (TPM)) on commodity servers to generate trusted proofs which are managed by efficient cryptographic construction, Merkle hash tree, for usage rights compliance. We integrated our framework with OpenStack and demonstrate that Metered Boot is able to achieve high scalability and low overhead for instantiating virtual network functions (VNFs).

A critical evaluation of cortical bone fracture toughness testing methods

Cortical bone fracture mechanics which quantifies the tissue's resistance to fracture is widely regarded as important to finding key determinants of bone fragility and fracture. Currently, the most widely used fracture mechanics approach is the J-integral resistance (J-R) curve as defined in ASTM E1820 standard. This standard employs an unloading compliance (UC) method to estimate crack extension, necessary for fracture toughness and resistance curve (R-curve) quantification. Further, this UC method requires a series of unload-reload cycles to be conducted during the fracture test. However, cortical bone violates some assumptions on which the UC method is based, which are: no energy loss during the unload-reload cycles and any change in unloading compliance is only due to crack extension. Consequently, the aim of this study was to examine the impact of the UC method on the accuracy of fracture toughness measurement for bovine cortical bone. Ten pairs of single edged notched bend specimens were prepared from the posterior diaphysis of bovine tibiae and underwent three-point bending fracture tests. The paired specimens were divided into two groups: a cyclic loaded group and a monotonic loaded group. Further, crack extension was determined by the UC method for the cyclic group and by an optical method for both the cyclic and monotonic groups. From these, three different approaches were used to generate J-R curves from which three fracture toughness parameters were computed and compared between the three approaches. This comparison allowed the impact of crack extension estimation by the UC method as well as the unload-reload cycles on the accuracy of the fracture toughness measures to be assessed. Results show that the UC method underestimates crack extension by an average error of 73%. In addition, the combined effects from crack extension estimation using the UC method and the unload-reload cycles lead to a significant overestimation of the specimen's fracture toughness measures. This highlights the need for more studies to establish a standardized approach to cortical bone fracture testing.

Improved Method for Fracture Toughness Testing Using Compliance Method for High Toughness Materials

Abstract In order to ensure the integrity of structures such as gas turbines and nuclear power plants, the materials used should have excellent toughness. Especially in the case of nuclear piping materials applied to leak before break (LBB) design, high toughness materials are used to meet the stringent fracture toughness criteria and integrity must be verified through static J–R curve testing using the compliance method, one of the measurement techniques for fracture toughness. The measured and estimated values for the crack extension length during the test should also match, within a certain tolerance. However, in the case of materials with high toughness, rotation of the specimen becomes significant, because the test is performed until the crack open displacement (COD) is relatively large to ensure sufficient crack extension. In this case, it is not easy to satisfy these conditions due to the rotational effect on the specimen. Even though ASTM E1820 suggests a method for correcting the crack length for the rotational effect on these specimens, it has been found that there are substantial differences for high toughness materials. To resolve this problem, a new crack length correction formula considering a large rotation effect is proposed. Through analysis of the data from J–R curve testing with this proposed method, it is confirmed that the accuracy of crack extension length estimation is improved compared to the existing method. The proposed method can well explain the variation of crack extension length due to rotation and is suitable as a correction equation for rotation of compact tension specimens.

SP8.1.4 Iatrogenic gallbladder perforation during laparoscopic cholecystectomy and outcomes: a systematic review and meta-analysis

Abstract Aims to compare the outcomes of iatrogenic gallbladder perforation versus no gallbladder perforation in patients undergoing laparoscopic cholecystectomy. Methods In compliance with PRISMA statement standards, electronic databases were searched to identify all studies comparing the outcomes of iatrogenic gallbladder perforation versus no gallbladder perforation in patients undergoing laparoscopic cholecystectomy. The outcome of interest included surgical site infection (SSI), postoperative collection, operative time and length of hospital stay. Random effects modelling was applied to calculate pooled outcome data. The certainty of evidence was assessed using GRADE system. Results A total of 5366 patients from 11 studies were included. Analysis of 5366 patients from 11 observational studies suggested that iatrogenic gallbladder perforation during laparoscopic cholecystectomy does not increase the risk of SSI (OR 1.48, 95% CI 0.57–3.86, P=0.42) and postoperative collection (RD 0.00, 95%CI -0.00–0.01, P=0.41) but may result in longer operative time (MD 10.28, 95% CI 7.40–13.16, P <0.00001) and length of hospital stay (MD 0.51, 95%CI 0.15–0.87, P=0.005). The results remained consistent through sensitivity analyses. The quality of available evidence was judged to be moderate and the GRADE certainty of the evidence was judged to be high. Conclusions Relatively robust evidence with high level of certainty suggests that iatrogenic gallbladder perforation during laparoscopic cholecystectomy may not increase the risk of SSI and postoperative collection but may result in longer operative time and length of hospital stay. Whether prompt retrieval of spilled stones, adequate peritoneal irrigation, and intraoperative use of prophylactic antibiotic contribute to the above findings remains unknown.

WE5.6 Hajibandeh index is more accurate than NELA score in predicting mortality following emergency laparotomy in patients aged over 80

Abstract Aims To compare performance of the Hajibandeh Index (HI) and National Emergency Laparotomy Audit (NELA) score in predicting mortality following emergency laparotomy (EL). Methods In compliance with STROCSS guidelines for observational studies a cohort study was conducted. All patients who underwent EL between January 2014 and January 2021 in our centre were included. The performance of HI and NELA score in predicting 30-day and 90-day postoperative mortality were compared. The discrimination of each test was evaluated using ROC curve analysis, classification using classification table and calibration using a plotted diagram of the expected versus observed mortality rates. Results Analysis of 700 patients showed that the predictive performance of the HI and NELA models were comparable (AUC: 0.86 vs 0.87, P=0.557). HI was significantly better than the NELA model in predicting postoperative mortality in patients aged over 80 (AUC: 0.85 vs 0.72, P=0.0174). The performances of both tools were comparable in patients with ASA status above 3 (AUC: 0.82 vs 0.82, P=0.9775), patients with intraperitoneal contamination (AUC: 0.77 vs 0.85, P=0.0728) and patients who needed a bowel resection (AUC: 0.85 vs 0.88, P=0.2749). Both tools were comparable in terms of classification and calibration. Conclusions Hajibandeh index is better than the NELA score in predicting mortality following EL in patients aged over 80. Its performance is comparable to NELA for all patients, patients with ASA status above 3, patients with intraperitoneal contamination or patients who need a bowel resection. We encourage other researchers to validate HI in predicting mortality following EL.

Shield or Sword? Moral Distress in Aged Care Employees Related to Regulation and Compliance

This paper reports on one finding of a qualitative study using interpretive phenomenological analysis (IPA) in a mixed-methods study examining the relationship between leadership style and job satisfaction in Australian aged care employees. The qualitative data suggest that aged care employees are experiencing moral distress relating to the regulatory environment that governs the aged care sector and the compliance processes adopted by regulators and accreditors. One of the reasons for the design and operationalisation of the regulatory environment is to protect vulnerable consumers, the public and the workforce. However, the findings of this research are that it is this environment that also causes damage to the aged care workforce. The question is whether compliance requirements and the regulatory scheme are a shield or sword. The causes of the moral distress were different for leaders and raters. This paper reports on this finding. Moral distress is one of three undesirable outcomes identified in the study and labelled as Workplace Maladies. Moral distress due to regulatory systems and processes experienced by leaders appears to be caused by different factors than the moral distress experienced by raters. Leaders experienced moral distress because of the system and methods of regulatory and standards compliance. In contrast, their followership experienced other regulatory processes such as the scope of practice for health professionals and the requirement to supervise and accept responsibility for unregulated workers who do not have a scope of practice. Unregulated workers reported that the absence of scope of practice is a cause of moral distress. Recommendations are made for changes to the system and processes of compliance assessment and action and for developing a scope of practice for unregulated workers to reduce the moral distress experienced by aged care employees and thus reduce workforce turnover in an already scarce workforce.

Moving China’s renewable portfolio standard forward: lessons from the US experiences

Abstract As China is transitioning to the renewable portfolio standard (RPS) regime, this article examines its nascent design and finds it incorporate insufficient forces to generate demand for the renewable resource. Moreover, without further clarification on the flexibility of compliance methods, China’s RPS tends to distort the electricity market. To move China’s RPS system forward, this article takes a close look at the experiences of mature RPS statutes in the New England states, as one bunch of RPS representatives in the USA, and argues critical components following a set of best practices, including a predictable and stable timeframe for stringent targets and the mandatory compliance mechanism with flexible rules. Nevertheless, as no consistent RPS exists across the USA, state-centered RPS statutes are caught up in legal disputes that highlight the necessity of China’s RPS enactment to ensure the compliance market does its job.

Critical evaluation of the chemical composition of acid mine drainage for the development of statistical correlations linking electrical conductivity with acid mine drainage concentrations

• Significant metals concentrations were present in AMD in Mpumalanga Coalfields. • Seasonal variability and strong correlations between electrical conductivity and major parameters were noted. • Electrical conductivity is easily measured and data are immediately available. • Electrical conductivity can be used as a proxy to predict concentrations of other major parameters. • Derivation of electrical conductivity values corresponding to water quality limits for the predicted parameters may be used as a rapid method for testing compliance. The design an effective treatment processes for the remediation of acid mine drainage (AMD) requires an understanding of the composition of the AMD water. The pH and elemental composition of AMD waters are site specific and are dependent on the regional geology, and environmental factors. To establish the chemical and physical characteristics of two AMD sites located in the Mpumalanga coal mining region, South Africa, samples were taken between February 2018 to April 2019. These data were compared against regulatory legislation, and the potential health effects of exposure indicated. Strong correlations were noted between parameters and statistical evaluation demonstrated that electrical conductivity (EC) could be a useful correlative for prediction of total acidity, dissolved iron, and sulfur concentrations in acidic AMD waters. From these findings, empirical correlations were used to derive regression equations which were used to derive the EC values corresponding to the respective water quality limits for total dissolved solids (TDS), dissolved iron, and sulfur to provide a rapid method for testing compliance. Given the site specificity of AMD composition, this approach is intended as a proof of concept for the development of a methodology for adaption at other AMD sites. The regression equations should not be considered as universal to all AMD sites and EC should also not be used as a replacement for more complete chemical analysis. :

Thermomechanical and isothermal fatigue crack propagation testing method for 316LN austenitic stainless steel

AbstractInvestigating fatigue crack growth behavior of materials is crucial to the life design and safety evaluation of engineering structures. During the practical service condition, the temperature keeps changing, which cannot be studied by the traditional fatigue crack growth test method at constant temperature. In this study, we focus on constructing a new thermomechanical fatigue (TMF) crack propagation testing method, developing a thermal deformation compensation method, and proposing an equivalent compliance method suitable for variable temperature conditions based on ASTM E647 standard to measure the crack length. Furthermore, the load‐ and strain‐controlled TMF tests under different phase angles are carried out to prove the validity of the new method.

An Algebraic Elimination by Substitution Algorithm for Vehicle–Bridge Interaction Problems

This paper proposes an algorithm to solve vehicle–bridge interaction (VBI) problems. It describes the VBI system in a linear second-order differential-algebraic equation (DAE) manner, incorporating the motions of both the vehicle and the bridge subsystems, together with the contact forces. On account of the conjugation between the VBI system’s motions and contact forces, the key feature of the proposed algorithm is to solve the DAE with the the algebraic method of elimination by substitution, avoiding the singularity of the differential operator. It enables a versatile and consensus solution scheme for different types of contact mechanisms, including the rigid contact model with constraints, the elastic contact model with the compliance method, and the creep tangential contact model, as well as different wheel–rail profiles. Combined with an appropriate numerical integration scheme, it allows an explicit expression of the contact forces, subsequently leading to the partitioned non-iterative analysis of the motions of both the vehicle and the bridge subsystems. In addition, by incorporating the dynamic condensation of wheels’ degrees of freedom into those of upper components in a matrix form, i.e. a reduced system approach, the proposed algorithm can avoid the numerical drift associated with the kinematic constraints on the acceleration level. To demonstrate the accuracy of the proposed approach, this study first examines a benchmark example of a single degree of freedom sprung mass model traversing a simply supported bridge. Further, it considers a more realistic problem of one and eight train vehicles crossing three three-span continuous bridges. The comparisons and the agreements with existing algorithms prove the accuracy and computational efficiency of the proposed analysis scheme.

Proportional topology optimisation with maximum entropy-based meshless method for minimum compliance and stress constrained problems

In this paper, proportional topology optimisation (PTO) with maximum entropy (maxent)-based meshless method is presented for two-dimensional linear elastic structures for both minimum compliance (PTOc) and stress constraint (PTOs) problems. The computation of maxent basis functions is efficient as compared to the standard moving least square (MLS) and possesses a weak Kronecker delta property leading to straightforward imposition of Dirichlet boundary conditions. The PTO is a simple, non-gradient, accurate, and efficient method compared to the standard topology optimisation methods. A detailed and efficient implementation of the computational algorithms for both PTOc and PTOs is presented. The maxent basis functions are calculated only once at the start of simulation and used in each optimisation iteration. Young’s modulus for each background cells is calculated using the modified solid isotropic material with penalisation (SIMP) method. A parametric study is also conducted on the degree of proportionality and history dependence of both PTOc and PTOs algorithms. A variety of numerical examples with simple and complex geometries, and structured and unstructured discretisations are presented to show the accuracy, efficiency, and robustness of the developed computational algorithms. Both PTOc and PTOs algorithms can handle large topological changes, and provide excellent optimisation convergence characteristics.

A New Creep-Fatigue Interaction Model for Predicting Deformation of Coarse-Grained Soil.

Studying the creep–fatigue interaction of the coarse-grained soil (CGS) is very important for safety assessment and disaster prevention in subgrade engineering. Current research work is mainly focused on single creep or fatigue deformation. In this paper, a new creep–fatigue interaction model is established to predict the creep–fatigue interaction deformation of different gradation CGS based on the rheological mechanics and the interactive relationship between creep and fatigue complex compliance method. Triaxial creep–fatigue interaction tests of different gradations CGS under different average stresses and frequencies were conducted to verify the new creep–fatigue interaction model. Research results show that for the creep–fatigue and fatigue–creep interaction, the fatigue deformation is always larger than the creep deformation under the same stress level. For the creep–fatigue multi-interaction, the second creep and fatigue deformation are always smaller than the first creep and fatigue deformation. The results of the triaxial creep–fatigue interaction tests verify the validity of this new model.

Comparison of Global and Regional Compliance-Guided Positive End-Expiratory Pressure Titration on Regional Lung Ventilation in Moderate-to-Severe Pediatric Acute Respiratory Distress Syndrome.

PurposeTo investigate the difference in the positive end-expiratory pressure (PEEP) selected with chest electrical impedance tomography (EIT) and with global dynamic respiratory system compliance (Crs) in moderate-to-severe pediatric acute respiratory distress syndrome (pARDS).MethodsPatients with moderate-to-severe pARDS (PaO2/FiO2 < 200 mmHg) were retrospectively included. On the day of pARDS diagnosis, two PEEP levels were determined during the decremental PEEP titration for each individual using the best compliance (PEEPC) and EIT-based regional compliance (PEEPEIT) methods. The differences of global and regional compliance (for both gravity-dependent and non-dependent regions) under the two PEEP conditions were compared. In addition, the EIT-based global inhomogeneity index (GI), the center of ventilation (CoV), and standard deviation of regional delayed ventilation (RVDSD) were also calculated and compared.ResultsA total of 12 children with pARDS (5 with severe and 7 with moderate pARDS) were included. PEEPC and PEEPEIT were identical in 6 patients. In others, the differences were only ± 2 cm H2O (one PEEP step). There were no statistical differences in global compliance at PEEPC and PEEPEIT [28.7 (2.84–33.15) vs. 29.74 (2.84–33.47) ml/cm H2O median (IQR), p = 0.028 (the significant level after adjusted for multiple comparison was 0.017)]. Furthermore, no differences were found in regional compliances and other EIT-based parameters measuring spatial and temporal ventilation distributions.ConclusionAlthough EIT provided information on ventilation distribution, PEEP selected with the best Crs might be non-inferior to EIT-guided regional ventilation in moderate-to-severe pARDS. Further study with a large sample size is required to confirm the finding.

Hajibandeh Index versus NELA score in predicting mortality following emergency laparotomy: A retrospective Cohort Study

ObjectivesTo compare performance of the Hajibandeh Index (HI) and National Emergency Laparotomy Audit (NELA) score in predicting postoperative mortality in patients undergoing emergency laparotomy. MethodsIn compliance with STROCSS guidelines for observational studies a cohort study was conducted. All patients aged over 18 who underwent emergency laparotomy between January 2014 and January 2021 in our centre were considered eligible for inclusion. The HI and NELA indices in predicting 30-day and 90-day postoperative mortality were compared. The discrimination of each test was evaluated using Receiver Operating Characteristic (ROC) curve analysis, classification using the classification table and calibration using a plotted diagram of the expected versus observed mortality rates. ResultsAnalysis of 700 patients showed that the predictive performance of the HI and NELA models were comparable (30-day mortality: AUC: 0.86 vs 0.87, P = 0.557; 90-day mortality: AUC: 0.81 vs 0.84, P = 0.0607). In terms of 30-day mortality, HI was significantly better than the NELA model in predicting postoperative mortality in patients aged over 80 (AUC: 0.85 vs 0.72, P = 0.0174); however, the performances of both tools were comparable in patients with ASA status above 3 (AUC: 0.82 vs 0.82, P = 0.9775), patients with intraperitoneal contamination (AUC: 0.77 vs 0.85, P = 0.0728) and patients who needed a bowel resection (AUC: 0.85 vs 0.88, P = 0.2749). In terms of 90-day mortality, HI was significantly better than the NELA model in predicting mortality in patients aged over 80 (AUC: 0.82 vs 0.71, P = 0.0214); however, NELA had better predictive value in patients with intraperitoneal contamination (AUC: 0.76 vs 0.85, P = 0.0268); the performances of both tools were comparable in patients with ASA status above 3 (AUC: 0.77 vs 0.80, P = 0.2582), and patients who needed a bowel resection (AUC: 0.81 vs 0.86, P = 0.05). Both tools were comparable in terms of classification and calibration. ConclusionsHajibandeh index was better than the NELA score in predicting postoperative 30-day and 90-day mortality in patients aged over 80 undergoing emergency laparotomy. Its performance in predicting 30-day and 90-day mortality was comparable with NELA score in other subgroups except 90-day mortality in patients with intraperitoneal contamination where the performance of NELA was better. We encourage other researchers to validate HI in predicting mortality following emergency laparotomy.

Conceptual Approach to Periodontal Microsurgery

Periodontal treatment modalities have evolved since the 20th century. This era of periodontal treatment is progressing towards minimally invasive techniques. Nowadays, microscopes and surgical loupes are being used in different fields of dentistry. Periodontal surgeries like root coverage procedures, esthetic surgeries, scaling &amp; root planing have also incorporated these methods for better esthetic results and patient compliance. Unlike in other fields of dentistry, there is more to be explored in the periodontal field with microsurgical methods. This article aims to discuss the evolution of periodontal treatment with microsurgical procedures and its principles. The literature concerning the efficacy of microsurgical approaches in treating periodontal diseases has been evaluated.

Research on the effect of thermal treatment on the crack resistance curve of marble using notched semi-circular bend specimen

The crack resistance curve is widely used to describe the complete fracture process of quasi-brittle materials. In the paper, the crack resistance curves of thermally treated marble were tested through the notched semi-circular bend specimens. The acoustic emission (AE) and digital image correlation (DIC) techniques were used to monitor the fracture behaviors of the specimens during the test. The AE results indicated that the crack will initiate from the notch when the axial load is less than the peak load. And, when the axial load reaches the peak load, the DIC results demonstrated that there exists a large fracture process zone (FPZ) in front of the crack notch. The effect crack length was calculated by the compliance method, which is coincided with the DIC results. The amplitude of the crack resistance curves decreases with the increase of treatment temperature, which suggested that the fracture resistance of the specimen declines due to thermal treatment. Based on the K-resistance curves, the initial fracture toughness, unstable fracture toughness, and fracture toughness when FPZ is fully formed have been determined for the thermally treated specimens. The results showed that these parameters both decrease in the increase of treatment temperature. Moreover, The FPZ length first increases and then decreases with the increase of normalized crack length and the critical and maximum non-dimensional FPZ length tends to increase with the increase in treatment temperature.