Entire Specimen Research Articles

Blood-Based Biomarker Panel for Personalized Lung Cancer Risk Assessment.

To investigate whether a panel of circulating protein biomarkers would improve risk assessment for lung cancer screening in combination with a risk model on the basis of participant characteristics. A blinded validation study was performed using prostate lung colorectal ovarian (PLCO) Cancer Screening Trial data and biospecimens to evaluate the performance of a four-marker protein panel (4MP) consisting of the precursor form of surfactant protein B, cancer antigen 125, carcinoembryonic antigen, and cytokeratin-19 fragment in combination with a lung cancer risk prediction model (PLCOm2012) compared with current US Preventive Services Task Force (USPSTF) screening criteria. The 4MP was assayed in 1,299 sera collected preceding lung cancer diagnosis and 8,709 noncase sera. The 4MP alone yielded an area under the receiver operating characteristic curve of 0.79 (95% CI, 0.77 to 0.82) for case sera collected within 1-year preceding diagnosis and 0.74 (95% CI, 0.72 to 0.76) among the entire specimen set. The combined 4MP + PLCOm2012 model yielded an area under the receiver operating characteristic curve of 0.85 (95% CI, 0.82 to 0.88) for case sera collected within 1 year preceding diagnosis. The benefit of the 4MP in the combined model resulted from improvement in sensitivity at high specificity. Compared with the USPSTF2021 criteria, the combined 4MP + PLCOm2012 model exhibited statistically significant improvements in sensitivity and specificity. Among PLCO participants with ≥ 10 smoking pack-years, the 4MP + PLCOm2012 model would have identified for annual screening 9.2% more lung cancer cases and would have reduced referral by 13.7% among noncases compared with USPSTF2021 criteria. A blood-based biomarker panel in combination with PLCOm2012 significantly improves lung cancer risk assessment for lung cancer screening.

Tensile properties of epoxy resin filled with activated carbon derived from coconut shell

Epoxy is one of the most widely used polymers. The aim of this research is to determine the potential of activated carbon derived from coconut shells as fillers in epoxy resin. 5 wt% of this filler was added to epoxy resin. The entire specimens were manufactured using a mold made out of aluminum strips with dumbbell shape according to ASTM D638 standard. Tensile properties of epoxy resin with and without filler were analyzed to observe the effect of activated carbon. The results showed that the addition of 5 wt% of activated carbon can decrease the tensile strength of epoxy resin, meanwhile increasing its elastic modulus.

In situ transmission electron microscopy observation of the deformation and fracture processes of an epoxy/silica nanocomposite.

Herein, we report the in situ transmission electron microscopy observation of the deformation and fracture processes of an epoxy resin thin film containing silica nanoparticles under tensile strain. Under tensile strain, the dispersed silica nanoparticles in the composite arrest the progress of the crack tip and prevent crack propagation. Concomitantly, the generation and growth of nanovoids at the epoxy matrix/nanoparticle interfaces were clearly observed, particularly in the region near the crack tip. These nanovoids contribute to the dissipation of fracture energy, thereby enhancing the fracture toughness. We also analyzed the local distributions of the true strain and strain rate in the nanocomposite film during tensile testing using the digital image correlation method. In the region around the crack tip, the strain rate increased by 3 to 10 times compared to the average of the entire test specimen. However, the presence of large filler particles in the growing crack suppressed the generation of strain, potentially contributing to hindering crack growth.

Incidental thyroid carcinoma: Correlation between FNAB cytology and pathological examination in 1093 cases

ObjectiveTo investigate Incidental Thyroid Carcinoma (ITC) by comparing the results of Fine Needle Aspiration Biopsy (FNAB) cytology and the postoperative pathological findings. MethodsData of 1479 patients who underwent total thyroidectomy were retrieved. Three hundred eighty-six patients were excluded due to insufficient data. Each surgical specimen studied received two histopathological diagnoses: the local diagnosis ‒ for the same area in which the FNAB was performed; and the final diagnosis, which includes a study of the entire surgical specimen. ResultsA thousand and ninety-three patients were investigated. FNAB result was malignant in 187 patients, benign in 204, suspicious or indeterminate in 668 cases, and inconclusive in 34 cases. The prevalence of ITC was 15.1%. Most of the ITC in this series was less than 0.5 cm. The incidence of ITC was higher in Bethesda III (17.5% ITC) and IV (19% ITC) than in Bethesda II cases (1.5% false negatives and 9% ITC). ConclusionAlthough the incidence of false-negative results in Bethesda II nodules is only 1.5%, 9% of these patients had ITC in the thyroid parenchyma outside the nodule that underwent preoperative FNAB. The incidence of ITC in the same scenario was even higher in Bethesda III (17.5%) and Bethesda IV cases (19%). Ultrasonography-guided FNAB is an excellent method for the assessment of thyroid nodules. However, biopsy sites should be carefully selected. Despite the high incidence of incidentalomas, total thyroidectomy should not always be the treatment of choice due to its rare but potentially serious complications. The findings of the present study can assist future clinical decisions towards active surveillance strategies for the management of papillary thyroid carcinoma.

Crack paths for mild steel specimens with circular holes in high cycle fatigue

The most common current models for predicting the fatigue limit in notched solids use the stresses along a straight line, beginning at the notch root, to make the prediction. This line represents a simplification of the path of a real crack, which usually has a first part, known as stage I, in the direction of the maximum tangential stress, and a second part, known as stage II, in the direction perpendicular to the maximum normal stress. In this work, experimental crack paths for notched solids are analysed, with the objective of establishing the directions and lengths of stages I and II of fatigue crack growth from notches. The material was a mild steel, the geometry of the specimen was a thin-walled tube with a passing-through hole and the tests were axial, with R = -1. From the tests, the S-N curves were constructed and the fatigue limits were calculated. For the high cycle fatigue tests, the cracks paths were studied, with special attention to the crack initiation point and the crack direction along the first grains. The cracks paths on the specimen outer surface were studied with an optical microscope. In this surface, the crack initiation point was close to the maximum principal stress point at the hole contour. The direction of the crack in the first and second grain showed great variability. This variability noticeably decreased as the crack reached a length of 10-20 grains, approaching the direction of Mode I. However, the crack might actually start at an interior point on the surface of the hole, which has a depth of 1500 μm. In fact, the point of maximum principal stress of the entire specimen is not at the specimen outer surface but on the internal surface of the hole at 750 μm from the outer surface, that is, half the thickness of the specimen. The crack path in the plane transverse to the hole containing this point of maximum principal stress was analysed. For this, the fracture surfaces, at both sides of the hole, were analysed with a non-contact 3D optical profiler. The crack path in this internal transverse plane followed the trend described for the crack path on the specimen outer surface: the initiation point close to the maximum principal stress point at the hole contour, great variability in the direction of the crack along the first grains and tendency to Mode I direction when the crack gets longer.

Using a pupal exuvia to designate the undamaged neotype of a species belonging to a complex of sibling species - the case of Aedes coluzzii (Diptera, Culicidae).

The mosquito species Aedes (Ochlerotatus) coluzzii Rioux, Guilvard & Pasteur, 1998 was distinguished from its sibling species Aedes detritus (Haliday, 1833) using an isoenzymatic method that required the destruction of the entire specimen, therefore no holotype was designated by the species authors. We aimed to designate a neotype for Ae. coluzzii from specimens collected from the type-locality and individually reared up to adult stage. Genomic DNA was extracted from pupal exuvia and ITS2 was sequenced, enabling verification of the identity of each specimen as Ae. coluzzii or Ae. detritus. Among the series of Ae. coluzzii, a male was designated as neotype and deposited in a collection. To our knowledge, this is the first time the type of a mosquito species is deposited thanks to its molecular identification from its pupal exuvia. The set of identified specimens allowed additional phylogenetic and morphologic studies.

Investigation on tensile behaviour of Al/Si3N4/sugarcane ash particles reinforced FSP composites

Composite materials are less weighty, stronger or also cheaper. A composite material is usually composed of two or more identical or different metals. It examines the mechanical behaviour, in the production of specimens in different silicon nitride compositions, of Aluminium Alloy 6063 metal matrix composites with controlled (or) bagasse ash (BA) and silicon nitride distribution. The Stir Casting and Friction stir processing (FSP) method is used to fabricating the AMCs. The mechanical behaviour of the entire specimen is examined in comparison to the existing composite materials, such as the modification of the hardness, tensile and compression tests. The work is aimed at producing an absolutely new composite material and at examining its mechanical properties with various reinforcement compositions.

Incidental Findings of Appendiceal Diverticulitis Presenting as Acute Appendicitis.

Diverticulosis of the appendix (DA) is a rare pathological finding that clinically imitates acute appendicitis and is most commonly found in adult males with chronic abdominal pain. It has a higher rate of perforation compared to acute appendicitis (84% vs 12%, P<0.01), and is consequently associated with a higher rate of mortality. Appendiceal diverticulitis has been found to have a significant association with incidental appendiceal neoplasms, therefore elective prophylactic appendectomy is recommended to prevent the risk of complications and to rule out the possibility of a coexisting neoplasm. Meticulous gross examination in addition to thorough histological examination of the entire appendectomy specimen by pathologists is essential in order to identify diverticula. We present two female patients with signs and symptoms consistent with acute appendicitis, they were found to have appendiceal diverticulitis on pathologic evaluation.

Design of in-plane torsion experiment to characterize anisotropic plasticity and fracture under simple shear

A novel experimental set-up is proposed to perform in-plane torsion experiments on grooved disk specimens. As compared to previously proposed systems, an enhanced clamping system is introduced to enable the torsion testing of high strength materials such as dual phase steels. The clamping is achieved without applying the clamping pressure through an axial actuator. Instead a custom-made washer-nut system is used which allows for the monitoring of the entire specimen front surface with cameras. Experiments are performed on three different steels (DC01, DP980, AISI301) to demonstrate the validity of the technique for measuring the stress–strain curve for strains of up to 2, for strain rate jump testing, for cyclic loading and for fracture testing. In particular, the demonstration experiments elucidate the importance of full field strain measurements during in-plane torsion. The strain fields vary along the gage section circumference in a periodic manner that is related to the anisotropy of the tested material. This important observation is confirmed through a finite element study covering a wide range of anisotropic Hill’48 materials with non-associated plastic flow.

Illustration of the connection between the vastus medialis obliquus muscle and the superficial medial collateral ligament of the knee: A human knee cadaveric study

Background: While the anatomy of the medial part of the knee has been extensively described, the muscular connections to the superficial medial collateral ligament (sMCL) have not been sufficiently studied. The purpose of this study is to describe the anatomy of the musculo-ligamentous connection between the sMCL and the Vastus Medialis Obliquus muscle (VMO), and to describe its anatomy. Methods: Six Human Cadaveric knees were used in this study. Donors were 4 males and 2 females with a mean age of 49 years old. Dissection was performed in fixed knee extension and directed to show the area of the proximal attachment of the sMCL. Results: A musculo ligamentous connection between the distal portion of the Vastus medialis Obliquus muscle and the sMCL has been identified in our entire specimens. The mean mid substance width of this connection was 9.75 (8.7 -10.8) mm, the mean length was 29.3 (22.2-36.4) mm and the mean thickness was 1.3 (0.9-1.7) mm. Conclusion: The proximal femoral attachment of the sMCL is directly connected to the distal end of VMO. This connection may show that the sMCL can possibly assist in the dynamic stabilization of the knee during extension against valgus stress, through its tension by the contracted VMO muscle.

Rapunzel syndrome: an uncommon tale of a long hairy tail - case report and review of literature

Trichobezoar is a rare clinical entity in which a ball of hair accumulates within the alimentary tract. When the tail of the trichobezoar extends into the small intestine, this condition is called Rapunzel syndrome (RS). A 14-year-old female presented with pain abdomen and vomiting for 2 weeks, and a history of trichotillomania and trichophagia, and an epigastric lump. A contrast enhanced computerized tomography (CECT) of the abdomen showed a grossly distended stomach with a heterogeneous mass containing trapped air with underlying normal mucosa suggestive of trichobezoar, with its tail extending into the proximal jejunum suggestive of RS. During laparotomy, a giant trichobezoar was seen in the stomach with its tail extending beyond the duodenum into the proximal jejunum. The entire specimen was delivered out intact. On follow up, she has no surgical complications, and was on behaviour therapy. Trichobezoars form when ingested hair strands become retained in the folds of the gastric mucosa and becomes entangled, forming a ball too large to exit the stomach. Trichotillomania and trichophagia are seen in many of these patients. Patients present with abdominal pain, vomiting, gastric outlet obstruction, and an epigastric mass. In the case of RS, complete removal without breakage and distal migration is important. RS should be considered as a differential diagnosis in a young girl with abdominal pain, vomiting, anaemia and upper abdominal lump. Early diagnosis prevents complications. Surgical removal is treatment of choice. Trichobezoar often coexists with psychiatric illness. Psychiatric evaluation, counselling and treatment are helpful in preventing recurrence.

Hepatoprotective effects of Lactobacillus plantarum 299v supplemented via drinking water against aflatoxin-induced liver damage

ABSTRACT The aim of this study was to examine the impact of intake of a lactic acid bacterium, Lactobacillus plantarum 299v (Lp299v) on aflatoxin-induced hepatotoxicity in broilers. For this, broilers were intoxicated with dietary aflatoxins and simultaneously treated with live Lp299v in drinking water. One-day-old male broilers were divided into eight groups (n = 10/group) as follows. Aflatoxin groups fed basal diet contaminated with aflatoxins (200 or 2000 ppb). The probiotic groups received drinking water enriched with live (Lp299v) (108 CFU/ml). A group of birds was given a commercial mycotoxin binder (2.5 g/kg feed). Control groups received basal diet without probiotic or aflatoxin binder. The growth performance was calculated for the entire period (0–42 days), and blood and liver specimens were processed for histology and determination of liver damage markers. Results showed extensive damage including bile duct hyperplasia, hepatocellular ballooning, and necrosis in chickens fed aflatoxin alone. However, liver lesions were limited to lobular inflammation and pyknosis in broilers treated with aflatoxins along with Lp299v. The histology of the liver tissues from the birds on aflatoxin-free diet + probiotic appeared to be normal when compared to the respective controls. Histopathological indices in different experimental groups were corroborated with the liver damage markers namely, serum ALT, AST, LD, and γ-GT. It is concluded that the improvement in the growth performance and prevention of aflatoxin-related liver lesions could be mainly assigned to the probiotic therapy for the entire period of breeding, although the aflatoxin-binding ability of the Lp299v in inactivation of aflatoxins cannot be ruled out. RESEARCH HIGHLIGHTS Aflatoxin-related liver damage progression was inhibited by probiotics in broilers. Aflatoxin inactivation by probiotics can be assessed by liver histopathology. Growth performance in broilers was improved following the intake of probiotics.

The Effect of Touch-Cure Polymerization on the Conversion and Hardness of Core Build-Up Resin Composites: A Laboratory Study.

To improve the self-curing capacity and interfacial strength with dentine of dual-cured composite materials, touch-cure activators have been introduced. The aim of the study was to evaluate the effect of these activators on the hardness and conversion of dual-cured resin composite core build-up restoratives. The materials tested were Clearfil DC Core Plus (CF) and Gradia Core (GC) with the corresponding adhesives Clearfil S3 Bond Plus (for CF) and G-Premio Bond/G-Premio DCA activator (for GC). Disk-shaped specimens (n = 6/group) were prepared for the following groups: dual-cured, self-cured and self-cured in contact with the adhesive activators at the bottom surface. After a 3-week storage period (dark/dry/37 °C) the Martens hardness (HM) and degree of conversion (DC%) were determined for the previously mentioned groups and the top surfaces of groups in contact with the adhesives. A statistical analysis was performed by a one-way ANOVA and Holm–Sidak test per material and a Pearson’s correlation analysis (HM vs. DC%) at an α = 0.05. The self-cured specimens resulted in significantly lower HM and DC% values from the dual-cured group, as expected. However, in the presence of the adhesives with touch-cure activators, the conversion of the self-cured groups showed insignificant differences in HM and DC% from the dual-cured in both composite materials. The improvements on the bottom composite surfaces in contact with the adhesives did not extend to the entire specimen length. Nevertheless, improved interfacial curing may improve interfacial durability.

Study on Fracture Mode of Gypsum under Shear Box Loading

The fracture mode under compressive shear loading is the research focus of rock fracture mechanics. In this paper, rock-like material with cracks was used to investigate its fracture mode. The physical and mechanical parameters of gypsum with specific paste-to-water ratio and curing time were measured by uniaxial compression test, and then, the shear box tests with loading angles of 0°, 15°, 30°, 45°, 60°, and 70° were carried out on gypsum specimens with initial double edge cut cracks. Finally, the strain field was monitored by the DIC method to analyze and summarize the phenomenon of crack initiation and propagation, and to analyze the fracture mode under shear box loading. The results show that the failure process of gypsum under uniaxial loading is a tensile split failure, and the fracture propagates through the entire specimen. Under the shear box loading, when the loading angle is less than 30°, the crack propagation presents a splitting tensile failure mode, that is, the crack propagation belongs to Mode I. When the loading angle is greater than 60°, the crack propagation shows shear failure mode after loading, that is, the crack propagation belongs to Mode II. While, when the loading angle is 45°, both the above two conditions exist, and the specimen presents both wing crack and secondary crack, in other words, the failure mode of the specimen is a superposition of shear fracture and tensile fracture. The research results can improve the understanding of the crack propagation mechanism of rock-like materials.

Direct observations of hydraulic fracturing in rock bridge of granite specimens in grain-scale

Hydraulic fracturing is a crucial and widely-used technology in shale gas exploitation and enhanced geothermal systems; the rock bridge will significantly affect the crack type and coalescence pattern of the hydraulically induced cracks. This paper aims to directly observe the fracturing process in rock bridge of granite specimens in grain-scale. Speckles are sprayed directly on the granite surface, which avoids covering hair-line cracks, and image quality assessment shows that the speckle pattern performs well in digital image correlation (DIC) calculations. Hydraulic fracturing was performed on two double-flawed granite specimens; a high-speed camera captured the entire specimens, and another recorded the rock bridge in grain-scale at a high frame speed simultaneously. The strain localization, crack propagation and morphology were analyzed based on the DIC method. Results showed that strain localization occurs for the first time approximately 20 seconds before failure, which is earlier than previously observed. When the displacement jump reaches a specific value, hair-line cracks appear, and then the crack propagation is the process of crack width increasing. The competition between hydraulically induced cracks often occurs in 120° rock bridge, which will cause one of the hair-line cracks near the inner tip of the flaw to close before failure.

Are Incisional Biopsies Reliable to Select Definitive Treatment in Patients with Ameloblastoma of the Jaws? A 15-year Interdisciplinary Retrospective Study

Ameloblastomas are tumors of odontogenic epithelium that, although benign, can have a locally aggressive course causing significant morbidity. WHO classifies ameloblastomas as 1 of 3 variants: solid/multicystic, unicystic, and peripheral. Resection, the standard treatment, is deemed curative, but can be debilitating to the patient. Unicystic subtype is considered less aggressive and could be treated with enucleation and curettage. The mercurial presentation of ameloblastomas makes the chosen treatment modality essential in decreasing the recurrence rates and associated morbidity. Definitive treatment is chosen based on an incisional biopsy, but a true diagnosis of unicystic ameloblastoma requires the entire specimen. The aim of this study is to assess the potential sampling error with an incisional biopsy and potential consequences on treatment outcomes at long-term follow-up.This is a retrospective cohort study for patients with ameloblastoma of the jaws treated at the Virginia Commonwealth University Department of Oral and Maxillofacial Surgery between 2005 to 2020. Patients with biopsy-proven ameloblastoma with a minimum of 1-year follow-up after definitive treatment and complete documentation were included. Predictor variables include radiographic findings, incisional biopsy, and histologic samples. Outcome variable is concordance between initial incisional biopsy and final treatment pathology, as well as recurrence rate.A total of 23 patients, 14 males and 9 females, met the inclusion criteria. Table 1 presents demographics and study variables for the sample. On initial incisional biopsy, 4 (17.4%) cases showed a “cystic” mention in the pathology report, 18 cases (78.3%) exhibited solid ameloblastoma, and 1 (4.3%) showed peripheral ameloblastoma. Final pathology after definitive treatment showed solid/multi-cystic ameloblastoma in 20 (87%) cases, 2 (8.7%) were unicystic, and 1 (4.3%) was peripheral ameloblastoma. Overall, initial incisional biopsy and final pathology were concordant in 21 (91%) cases. After histologic investigation, the initial biopsy for 3 (13%) cases exhibited sampling error, which is defined as the sampled tissue not being representative of the entire lesion (Table 2).Segmental resection was the definitive treatment in 14 (60.9%) cases while enucleation and curettage (E&C) were used on 6 (26.1%), and decompression followed by enucleation and curettage on 3 (13%) patients (Table 3). Postoperative follow-up from the day of definitive treatment ranged from 1 year to 15.6 years (mean 3.50 ± 3.22). Four patients (17.4%) had recurrent lesions, with 100% of them seen following conservative management (i.e., E&C or decompression with E&C). The time of recurrence after treatment ranged from 6 months to 10.75 years (mean 4.62 ± 4.25), with 1 case having more than 1 recurrence.Incisional biopsies are acceptably reliable when combined with clinical exam of the lesion and radiographic presentation to select definitive surgical treatment for ameloblastoma. The chance of sampling error should be included in the informed consent with a low threshold for second incisional biopsy when clinical/radiographic findings are not consistent with histopathological report. Consult with an oral and maxillofacial pathologist is essential, both at initial and final histopathology evaluation. Future development of less-invasive treatments that combine medical and/or surgical management, given the benign nature of ameloblastoma, will help patients achieve cure in the long term.

The megalopal stage of the hydrothermal vent crab Austinograea rodriguezensis Tsuchida amp; Hashimoto, 2002 (Decapoda: Bythograeidae): a morphological description based on CLSM images.

The Bythograeidae is unique amongst brachyuran crab taxa as it is the only family where all 6 genera and 16 species are endemic to hydrothermal vents. During the research conducted by German Federal Institute for Geosciences and Natural Resources to identify inactive polymetallic sulphide deposits along Central and Southeast Indian Ridges, the INDEX project collected from hydrothermal vent fields 6 Bythograeidae megalopae. Entire specimens and dissected appendages were stained, mounted on slides and examined using Light Microscopy and Confocal Laser Scanning Microscopy. Additional molecular analysis using mtCOI confirmed the identification of the specimens as Austinograea rodriguezensis Tsuchida Hashimoto, 2002. The megalopal stage of A. rodriguezensis shows similarities and distinctions between the characters of two other bythograeid megalopae, Bythograea thermydron Williams, 1980, and B. microps Saint Laurent, 1984. Unlike other brachyuran megalopae, B. thermydron and A. rodriguezensis lack long serrate setae and stout serrate spines on the dactylus of the fifth pereiopod. In both species no coxal spines on the pereiopods were observed. The elliptical carapace of B. thermydron is broader than long vs longitudinally rectangular in A. rodriguezensis. This carapace shape resembles B. microps more than B. thermydron, however, the dorsal surface of B. microps carapace is densely covered in short setae vs only covered with short setae on the anterior 1/4 and the posterior 1/6 length of carapace in A. rodriguezensis. Furthermore, the amount of plumose natatory setae on the pleopods in B. microps is in total larger and more variable, than in A. rodriguezensis. Bythograeid megalopae seem quite generalized and miss specific features that reveal them distinctively as endemic vent crab. A distinction from other species is possible by observing the unique combinations of certain characters. This is the first megalopal stage description of Austinograea and the fourth within the Bythograeidae.

Complete root specimen of plants grown in soil-filled root box: sampling, measuring, and staining method

BackgroundDetailed datasets containing root system and its architecture in soil are required to improve understanding of resource capture by roots. However, most of the root study methods have paid little attention to make and preserve whole root specimens. This study introduces root system sampling equipment that makes the entire root specimen with minimum impairment and without displacement of the spatial arrangement of the root system in root boxes. The objectives are to assess: whether the equipment can rapidly sample the entire root system; whether root surface area is measurable from a scanned digital image of the root specimen; and whether staining of the entire root specimens would provide multidimensional visual information on the interaction between soil and physiological function of root system architecture (RSA). For validation, we examined the root response of two soybean cultivars to arbuscular mycorrhizal (AM) inoculation and the effect of waterlogging stress on the physiological activity of buckwheat RSA.ResultsThe root boxes allowed soybean and buckwheat plants to grow uniformly across the replications. Both species showed significant differences between cultivars and/or among treatments in shoot and root traits. The equipment enabled to sample the whole-root specimens of soybean and buckwheat, where the tips of the fine roots were alive (diameter < 0.2 mm). Also, the whole root specimens of soybean were made in about 7 min. The root surface area calculated from the scanned soybean specimens showed a significant correlation with that calculated from the roots spread out in water (a common method). Staining of the soybean root specimens enabled us to observe the localized root proliferation induced by AM colonization. Moreover, staining of the buckwheat root specimens made it possible to examine the respiratory activity of each root at different depths.ConclusionsThe present method realized: fast and accurate production of the whole root specimen and precise calculation of the specimens’ root surface area. Moreover, staining of the root specimens enabled analyzing the interaction between soil and physiological function of RSA. The evaluation of root traits, using our methods, will contribute to developing agronomic management and breeding program for sustainable food production.

Numerical Simulation of Fracturing in Coals Using Water and Supercritical Carbon Dioxide with Potential-Based Cohesive Zone Models

The Park-Paulino-Roesler (PPR) cohesive zone model (CZM) for coal was established for analyzing mixed-mode I/II fractures using semicircular specimens under punch-through shear (PTS) and three-point bending (SCB) tests. In these methods, the main parameters of the fracture were obtained through SCB tests and PTS tests. And according to the experimental results, the coal specimens show obvious characteristics of ductile fracture under mode I and II loading. Moreover, hydraulic and supercritical carbon dioxide (ScCO2) fracture tests were conducted, and accordingly, it was found that the crack initiation pressure of coal specimens for hydraulic fracturing is 17.76 MPa, about 1.59 times that driven by ScCO2. And the crack initiation time of coal with ScCO2 fracturing is 123.73 s, which is 1.58 times that for hydraulic fracturing. A macrocrack eventually formed in the coal specimen due to the hydraulic drive, which penetrated through the entire specimen. Yet, there was no crack penetrating the whole fracture specimen and several widely distributed secondary cracks in the fractured coal specimens by ScCO2. Furthermore, zero-thickness pore pressure cohesive elements were utilized to investigate multicrack propagation in coals undergoing hydraulic and ScCO2 fracturing. The constitutive relationships of the established PPR CZM were introduced into the cohesive elements. The obtained results are consistent with the hydraulic and ScCO2 fracturing experiment results for the coal specimens. This indicates that the established PPR CZMs can accurately represent the crack propagation behavior in coals for hydraulic and ScCO2 fracturing.

Local crack growth evaluation in a fully lamellar Ti-6Al-4V alloy using an electrothermal Crack-Tip marking technique

Local crack growth properties within microstructural components are often anisotropic and difficult to measure, especially in materials like titanium alloys, that do not respond well to conventional, stress-ratio-based crack tip marking techniques. A method is described to extract a 3D anisotropic crack growth model from a common triplet colony type in titanium alloys, consisting of three grain-orientation variants of alpha-phase sharing a common 1¯21¯0 plane, parallel to a 111 (octahedral) plane from a parent beta grain. A fatigue crack growth test was run using a novel axisymmetric specimen (Pettit, 2021) of Ti-6Al-4V with an extremely coarse, fully lamellar microstructure. The microstructure consisted of ∼ 10 mm diameter beta grains, one of which had spanned nearly the entire specimen cross section of crack growth, and had decomposed to multiple regions of triplet basketweave microstructure during colony from above the beta transus. During pauses in the test, a succession of crack fronts was recorded on the fracture surface using a novel electrothermal crack tip marking technique (Pettit, 2021; Pettit, 2019) as the crack propagated through these colonies. Crack growth data was then extracted from post-test microscopy to obtain local crack growth rates. The position of the crack front on successive cycles and the fracture surface topography were correlated to local microstructural features using electron backscattered diffraction analysis following minimal polishing of the fracture surface. A numerical model was developed in Franc3D to quantify local crack driving forces. Local triplet-colony crack growth data was fit to a 3D anisotropic crack growth model. Both the crack growth rate and the fracture morphology in the triplets were strongly dependent on the crack orientation relative to the triplet axis. Crack propagation in a direction normal to the octahedral plane was estimated to grow 2.88x faster than crack growth within the octahedral plane at the same crack driving force. The methodology described appears promising for local crack growth evaluation.