Complete Specimens Research Articles

Postcranial anatomy of Besanosaurus leptorhynchus (Reptilia: Ichthyosauria) from the Middle Triassic Besano Formation of Monte San Giorgio (Italy/Switzerland), with implications for reconstructing the swimming styles of Triassic ichthyosaurs

Besanosaurus leptorhynchus Dal Sasso & Pinna, 1996 was originally described on the basis of a single complete fossil specimen excavated near Besano (Italy). However, a recent taxonomic revision and re-examination of the cranial osteology allowed for the assignment of five additional specimens to the taxon. Here, we analyse, describe and discuss the postcranial anatomy of Besanosaurus leptorhynchus in detail. The size of the specimens examined herein ranged from slightly more than one meter to eight meters. Overall, several diagnostic character states for this taxon are proposed, demonstrating a mosaic of plesiomorphic and derived features. This is best exemplified by the limbs, which show very rounded elements in the forelimbs, and pedal phalanges with retained rudimentary shafts. We suggest that the widely spaced phalanges in the forefins of Besanosaurus leptorhynchus were embedded in a fibrocartilage-rich connective tissue, like in modern cetaceans. We also review the similarities of Besanosaurus with Pessopteryx and Pessosaurus, allowing us to conclude that Besanosaurus is not a junior synonym of either of the two taxa. Lastly, to test the swimming capabilities of Besanosaurus leptorhynchus, we expanded on a previously published study focussing on reconstructing the swimming styles of ichthyosaurs. Besanosaurus leptorhynchus was found to possess a peculiar locomotory mode, somewhat intermediate between anguilliform swimmers, such as Cymbospondylus and Utatsusaurus, and some shastasaur-grade (e.g., Guizhouichthyosaurus) and early-diverging euichthyosaurian (e.g., Californosaurus) ichthyosaurs. Based on our results, we furthermore suggest that mixosaurids acquired their characteristic body profile (dorsal fin and forefins that are distinctly enlarged compared to the hindfins) independently and convergently to the one that later appeared in Parvipelvia. Moreover, the different swimming styles inferred for Cymbospondylus, Mixosauridae, and Besanosaurus strengthen the earlier hypothesis of niche partitioning among these three distinct ichthyosaur taxa from the Besano Formation.

Feasibility of triple assessment of the anastomosis using an anastomotic checklist.

Colorectal cancer is the third most common cancer and the second highest cause of cancer mortality in Australia. Despite advances in colorectal surgery, anastomotic leak still occurs in low-risk patients and is a substantial cause of morbidity and mortality. Many operative strategies are used to assess anastomotic integrity such as an air leak test or intraoperative flexible sigmoidoscopy, however an objective anastomotic checklist is yet to be developed and studied. This study aims to develop a photodocumentary anastomotic specific checklist and determine its feasibility for implementation. Patients undergoing left sided colorectal resections with primary anastomosis without a de-functioning ileostomy were prospectively included between May 2021 and December 2022. A photographic checklist assessing anastomotic perfusion, integrity via either air test or endoscopic image, evidence of complete operative doughnut specimens and the assessment of tension was implemented. The feasibility of an anastomotic checklist was externally validated by four independent colorectal surgeons from Australia, New Zealand and United States of America. The anastomotic checklist was completed in 44 patients. Mean age was 62 years, with 43% male and mean BMI 28. Operations included high anterior resection (45%), low anterior resection (18%), ultra-low anterior resection (20%), reversal of Hartmann's (11%). Median length of stay was 4 days. Complications post operatively were documented in six patients with anastomotic leak in 2% and wound infection in 6.8%. Intraclass correlation coefficients were poor amongst all reviewers with air leak and tension having no inter-reviewer correlation. The introduction of an anastomotic checklist was a feasible tool to systematically assess and document anastomotic integrity. Unfortunately, with the small sample size there was significant discrepancy in inter-observer variability, and this led to poor correlation regarding which patients were typically high risk requiring a temporary ileostomy. Larger studies on the implementation of an anastomotic checklist will be needed to evaluate if it is an inherently feasible approach and if there is an effect on anastomotic leak.

The contribution of the Middle Triassic fossil assemblage of Monte San Giorgio to insect evolution

The Triassic represents a critical period for understanding the turnover of insect fauna from the Paleozoic to the Mesozoic following the end-Permian mass extinctions (EPME); however, fossil deposits from the Early-Middle Triassic are scarce. The exceptionally preserved 239 million-year-old fossil insect fauna recorded at Monte San Giorgio (Switzerland), including 248 fossils representing 15 major insect clades is presented here. Besides the exceptional features, including their small size and excellent preservation, the fossils have importance in the evolutionary history of the group. The taxonomic and ecological diversity recovered, including both freshwater (dragonflies and caddisflies) and terrestrial taxa (true bugs and wasps), demonstrates that complex environments sustained a paleocommunity dominated by monurans (thought not to have survived the EPME), midges, and beetles. Interestingly, a blattodean-like fossil bearing an external ootheca was also found, important for understanding Paleozoic roachoids to extant cockroaches’ transition and the evolution of maternal brood care. Moreover, the youngest and first complete specimen of †Permithonidae and the oldest sawfly fossils were discovered. Finally, round-shaped bodies, compatible with seminal capsules or lycophyte spores, were found on the abdomens of several midge-like individuals. If these are spores, non-seed-bearing plants could have been the first entomophilous plants rather than gymnosperms, as recently supposed. Altogether, these fossils contribute substantially to understanding insect evolution and Paleozoic-Mesozoic faunal turnover.

A new approach to the fossil flamingo from Pie de Vaca locality (Puebla, central México) and some taxonomic and biogeographic implications

Pie de Vaca is a late Cenozoic site located in the municipality of Tepexi de Rodríguez, Puebla, Mexico. It is known for its ichnofossil record including footprints of camelids, carnivores, and peccaries, as well as the taphoglyph of an almost complete flamingo skeleton. This fossil specimen was previously identified as Phoenicopterus stocki, a small extinct species, through linear osteometric comparisons of the tibiotarsus. This study presents new data on the morphological features of the taphoglyph skull impression. The extant genera Phoenicopterus, Phoenicoparrus, and Phoeniconaias differ in the morphology and size of the skulls. The fossil specimen analyzed exhibits a small head and a distinct cranial shape when compared to those genera. The results confirm that the taphoglyph belongs to an adult of a small phenicopterid. The two-dimensional morphometric comparisons of the tibiotarsus based on the ratio of distal depth to distal width shows that the taphoglyph is larger than Phoeniconaias minor and Phoenicopterus minutus, and more similar to Phoenicopterus ruber. The analysis revealed previously unknown characteristics of the taphoglyph and refutes its previous identification as the extinct species Phoenicopterus stocki. The specimen appears to be a small adult flamingo, but it differs from known extant genera. These findings confirm the presence of a group of small flamingos in the late Cenozoic of North America and Mexico, with the most complete specimen being the taphoglyph of Pie de Vaca. However, further research remains necessary to establish its connections with extinct and extant phenonicopterids.

Commercially Available Guides Overestimate Socket Length During Anterior and Posterior Cruciate Ligament Socket Retrograde Drilling

To objectively assess the accuracy of socket measurements taken during cruciate ligament reconstruction using a retrograde reaming technique. Six complete knee sawbone specimens were used to ream anterior and posterior cruciate ligament sockets in the femur and tibia in a retrograde fashion using a standard retrograde reaming device. The longest and shortest sides of the sockets were measured using a ruler. One-sided Wilcoxon signed-rank sum tests were used to evaluate whether the actual measured socket length matched the estimated length set on the drill guide. One fellowship-trained surgeon reamed 24 total sockets in sawbone specimens using guides. Statistical analysis revealed a significant difference between the estimated measurement and the actual shortest tunnel length in each of the sockets. The median short side socket lengths were shorter than their respective intended depths by 4 mm for the femoral anterior cruciate ligament socket, 6 mm for the femoral posterior cruciate ligament socket, 6 mm for the tibial anterior cruciate ligament socket, and 4.5 mm for the tibial posterior cruciate ligament socket. All differences were significant at α= 0.05. The estimated cruciate socket lengths reamed during ligament reconstruction using a retrograde reamer and standard intra-articular measuring instrumentation were greater than the actual measured socket lengths. Successful cruciate ligament reconstruction relies on accurate socket measurements. This study examined the accuracy of commercially available cruciate ligament socket drill guides and the implications for clinical practice, to include graft-tunnel mismatch and surface area available for healing. Surgeons may consider reaming slightly longer than estimated sockets when performing all-inside cruciate ligament reconstructions to ensure appropriate socket depth for graft fixation.

Compound osteoderms preserved in amber reveal the oldest known skink

Scincidae is one of the most species-rich and cosmopolitan clades of squamate reptiles. Abundant disarticulated fossil material has also been attributed to this group, however, no complete pre-Cenozoic crown-scincid specimens have been found. A specimen in Burmite (99 MYA) is the first fossil that can be unambiguously referred to this clade. Our analyses place it as nested within extant skinks, supported by the presence of compound osteoderms formed by articulated small ostedermites. The specimen has a combination of dorsal and ventral compound osteoderms and overlapping cycloid scales that is limited to skinks. We propose that this type of osteoderm evolved as a response to an increased overlap of scales, and to reduced stiffness of the dermal armour. Compound osteoderms could be a key innovation that facilitated diversification in this megadiverse family.

Theropod teeth palaeodiversity from the uppermost Cretaceous of the South Pyrenean Basin (NE Iberia) and the intra-Maastrichtian faunal turnover

The South Pyrenean Basin has yielded abundant dinosaur and penecontemporaneous vertebrate fossils, becoming one of the most important areas in Europe for the study of these faunas. The studied isolated theropod teeth from the Western Tremp Syncline (NE Iberia) were recovered from the uppermost Maastrichtian (topmost Arén and Tremp formations). The studies conducted have led to the identification of eight tooth morphotypes, which are referred to cf. Paronychodon, cf. Richardoestesia, an abelisaurid, a dromaeosaurid, and a non-dromaeosaurid paravian. Together with the previously reported troodontid and ornithuromorph, this study increases the known theropod palaeobiodiversity in the area to seven taxa. The latest Maastrichtian theropod fauna of the Western Tremp Syncline is thus composed of a medium to large-sized abelisaurid as well as a high diversity of small-bodied early-branching coelurosaurians and avialans, as seen in other Ibero-Armorican localities. Revision of the literature concerning the theropods of the Ibero-Armorican domain indicates that, although similar theropod groups were present before, during, and after the intra-Maastrichtian faunal turnover (an event constrained to between the early Maastrichtian and the early late Maastrichtian; lower part of C31r to the C30r/C30n reversal), there were changes in the abelisaurid, dromaeosaurid, and large avialan assemblages, as well as in the proportions of indeterminate paravian and cf. Richardoestesia morphotypes, with the presence of troodontids only recorded in post-turnover faunas. These changes suggest that theropods might have been affected by the turnover event. Nevertheless, further studies and more complete specimens could shed more light on the effects of this faunal turnover, and on the affinities and palaeobiodiversity of the latest Cretaceous Ibero-Armorican theropods.

Haliskia peterseni, a new anhanguerian pterosaur from the late Early Cretaceous of Australia

Pterosaur remains have been reported from every continent; however, pterosaur skeletons remain rare. A new pterosaur is presented here, Haliskia peterseni gen. et sp. nov., constituting the most complete specimen from Australia from the upper Albian Toolebuc Formation of the Eromanga Basin (Queensland, Australia). A combination of features, including the presence of a premaxillary crest and curved teeth, and the morphology of the scapulocoracoid, support its referral to Anhangueria. Haliskia can be distinguished from all other anhanguerian pterosaurs based on two dental characters: the 4th and 5th tooth pairs are smaller than the 3rd and 6th, and the 2nd and 5th alveoli are smaller than 3–4 and 6–8. Moreover, the hyoid is 70% the total length of the mandible. The phylogenetic analyses presented here place Haliskia within Anhangueria. In one analysis, Haliskia and Ferrodraco are resolved as sister taxa, with Tropeognathus mesembrinus sister to that clade. The other resolves Haliskia, Mythunga and Ferrodraco in a polytomy within Tropeognathinae. The new Australian pterosaur attests to the success of Anhangueria during the latest Early Cretaceous and suggests that the Australian forms were more taxonomically diverse and palaeobiogeographically complex than previously recognized.

Morphology, taxonomy and trophic interactions of rostrum-less coleoids from the Late Triassic Polzberg Konservat-Lagerstätte (Lower Austria)

AbstractColeoid cephalopods are widespread from the Mesozoic till today. The extinct group of the Phragmoteuthida is thought to represent either stem-neocoleoids, stem-decabrachians, or stem-octobrachians. The well-known, almost complete specimens of Phragmoteuthis bisinuata from the Carnian Polzberg Konservat-Lagerstätte near Lunz am See (Lower Austria, Northern Calcareous Alps) and Cave del Predil (Northern Italy, Julian Alps) come from historical collections. These specimens do not reflect the entire coleoid assemblage within this environment. In order to obtain a more complete picture of the Carnian coleoid fauna, 430 coleoid specimens from the Polzberg locality and 60 specimens from contemporaneous localities around Cave del Predil were studied in detail. All available elements (phragmocones, proostraca, cartilages, hooks, beaks, ink sacs) attributed to the coleoid fauna were recorded, measured and evaluated taxonomically and taphonomically. Reviews of historical collection material permitted comparisons with recently collected material. The notation of co-occurrences of other faunal elements yielded insights into the palaeoecological context of this Upper Triassic environment within the Polzberg Basin. The new material from Polzberg does not support the previous assumption of a monospecific composition of the Polzberg coleoid fauna. Instead, we report the occurrence of the new phragmoteuthid Phragmoteuthis polzbergensis nov. sp. and a newly excavated specimen of Phragmoteuthis indicates the presence of ten arms within the group of the Phragmoteuthida for the first time. Phragmocones with small opening angles combined with cylindrical (roundly closed) body chambers, and arm hook types which are unusual for phragmoteuthids indicate the presence of the basal coleoid group comprising the rostrum-less genus Mojsisovicsteuthis.ZooBank LSID: urn:lsid:zoobank.org:pub:7EE7425C-6B0C-4800-925A-52D9108C13C7.

A new species of a snapping turtle (Pan-Chelydridae/Chelydropsis) from the Upper Miocene (MN9, early Vallesian) of Southwest Germany

ABSTRACT Chelydropsis is a genus of the clade Pan-Chelydridae, which existed and was distributed in Eurasia from the Eocene to the end of the Pliocene. The Chelydropsis fossil record of North of the Alps is particularly rich throughout the Miocene. In this study, we describe a new Chelydropsis species from the Late Miocene (Vallesian, MN9) fossiliferous site of Höwenegg in southwestern Germany. The new species is based on a nearly complete Chelydropsis skeleton, which stands out among the best preserved and most complete specimens ever found until now. The new species, Chelydropsis heweneggensis sp. nov. is of particular importance. It differs from the coeval Chelydropsis murchisoni, which recent studies suggest is the only Chelydropsis species known to have existed in Europe from the Middle Miocene to the Pliocene. The species described herein thus adds to the diversity of the European Neogene Chelydropsis record.

Abstract PO1-27-03: Studies on factors for pathological complete response after neoadjuvant chemotherapy in relation to HER2 status in primary breast cancer

Abstract Background: Neoadjuvant chemotherapy (NAC) has been increasingly used as the frontline therapy for the management of high-risk localized breast cancer (BC). Achieving pathological complete response (pCR) following NAC is associated with significantly better disease-free (DFS) and overall survival (OS), particularly for triple negative (TN) and HER2+ breast cancer. Among HER2 negative BC, HER2-low BC is a newly defined subset that has a HER2 immunohistochemical (IHC)-1+ or 2+/ISH negative phenotype. HER2 status is divided into 3 categories: HER2 positive, HER2-low, and HER2-zero. In this study, we investigated factors for pCR in relation to HER2 status and survival after NAC. Methods: A total of 197 cases with primary BC from January 2013 to July 2023 were enrolled in this study. There were 83 HER2 positive cases (including 7 HER2 2+/ISH+ cases) and 114 HER2 (78 HER2-low and 36 HER2-0) negative cases. HER2 3+ was dichotomized according to the staining cell rate (cut-off point; 90%) into the following two groups; HER2 3+/>90% (70 cases) and HER2 3+/< 90% (6 cases). The chemotherapy regimen was anthracycline and taxane with the addition of anti-HER2 therapy if the cases were HER2-positive. The clinicopathological factors examined were age, nodal status, tumor size, ER/PgR (cut-off points; 1% and 10%), and the Ki-67 index value (cut-off points: 20% and 40%). pCR was defined as the absence of residual invasive cancer on H&E evaluation of the complete resected breast specimen (ypT0/Tis). We investigated the correlation between pCR and clinicopathological factors. The DFS and OS were calculated using the Kaplan-Meier method and analyzed using the log-rank procedure. Uni- and multivariate analyses of factors for pCR were performed using regression analysis. Results: 1. pCR was observed in 48 cases (57.8%) after NAC in the HER2 positive group and 17 cases (14.9%) in the HER2 negative group. 2. There was no significant relationship between the pCR rate and ER, PgR, Ki-67, menopausal and nodal status in the HER2 positive group. However, pCR was significantly observed more often in smaller tumors. HER2 3+( >90%) had a significantly higher pCR rate than HER2 3+(≤90%) and HER2 2+(ISH+). Multivariate analysis revealed that HER2 3+( >90%) and tumor size (≤5cm) were significant factors for pCR in HER2 positive BC cases. 3. Patients with pCR after NAC had significantly better DFS in HER2 positive BC cases. 4. There was a significant correlation between the pCR rate and ER≤10%, PgR≤10% and tumor size < 5cm in the HER2 negative BC cases. There was no relationship between the pCR rate and the HER2 status; 19.4% in HER2-0 and 12.8% in HER2-low. 5. Multivariate analysis revealed that the PgR status and tumor size were significant factors for pCR in the HER2 negative BC cases. 6. There was no significant difference in DFS between patients with pCR and non-pCR, especially in the luminal type BC cases. Moreover, no significant difference was observed between HER2-low and HER2-0. Conclusion: pCR rate after NAC was 57.8% in the HER2 positive cases and 14.9% in the HER2 negative cases. Moreover, the HER2 3+( >90%) group had a significantly higher pCR rate than the HER2 3+(≤90%) and HER2 2+(ISH+) groups. There was no correlation between the HER2 status (HER2-low and HER2-0) and pCR rate in the HER2 negative BC cases. In addition, the ER/PgR negativity (≤10%) was a significant factor for pCR in the HER2 negative cases. These findings suggest that the IHC data on the HER2 and ER/PgR status may be effective in predicting the pCR rate after NAC in BC cases. Citation Format: Nobuyuki Arima, Reiki Nishimura, Kazuhiro Muramoto, Atsushi Inayoshi, Tomio Tanigawa, Sugiko Watanabe. Studies on factors for pathological complete response after neoadjuvant chemotherapy in relation to HER2 status in primary breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-27-03.

A three miRNAs panel in paraffin tissue serves as tool for predicting prognosis of renal cell carcinoma.

Renal cell carcinoma (RCC) stands as the most prevalent form of urogenital cancer. However, there is currently no universally accepted method for predicting the prognosis of RCC. MiRNA holds great potential as a prognostic biomarker for RCC. A total of 100 cases with complete paraffin specimens and over 5-year follow-up data meeting the requirements were collected. Utilizing the clinical information and follow-up data of the specimens, an information model was developed. The expression levels of eight microRNAs were identified using RT-qPCR. Finally, determine and analyze the clinical application value of these microRNAs as prognostic markers for RCC. Significant differences were observed in the expression of two types of miRNAs (miR-378a-5p, miR-23a-5p) in RCC tissue, and three types of miRNAs (miR-378a-5p, miR-642a-5p, miR-23a-5p) were found to be linked to the prognosis of RCC. Establish biomarker combinations of miR-378a-5p, miR-642a-5p, and miR-23a-5p to evaluate RCC prognosis. The combination of three microRNA groups (miR-378a-5p, miR-642a-5p, and miR-23a-5p) identified in paraffin section specimens of RCC in this study holds significant potential as biomarkers for assessing RCC prognosis.

Exceptionally preserved shark fossils from Mexico elucidate the long-standing enigma of the Cretaceous elasmobranch Ptychodus.

The fossil fish Ptychodus Agassiz, 1834, characterized by a highly distinctive grinding dentition and an estimated gigantic body size (up to around 10 m), has remained one of the most enigmatic extinct elasmobranchs (i.e. sharks, skates and rays) for nearly two centuries. This widespread Cretaceous taxon is common in Albian to Campanian deposits from almost all continents. However, specimens mostly consist of isolated teeth or more or less complete dentitions, whereas cranial and post-cranial skeletal elements are very rare. Here we describe newly discovered material from the early Late Cretaceous of Mexico, including complete articulated specimens with preserved body outline, which reveals crucial information on the anatomy and systematic position of Ptychodus. Our phylogenetic and ecomorphological analyses indicate that ptychodontids were high-speed (tachypelagic) durophagous lamniforms (mackerel sharks), which occupied a specialized predatory niche previously unknown in fossil and extant elasmobranchs. Our results support the view that lamniforms were ecomorphologically highly diverse and represented the dominant group of sharks in Cretaceous marine ecosystems. Ptychodus may have fed predominantly on nektonic hard-shelled prey items such as ammonites and sea turtles rather than on benthic invertebrates, and its extinction during the Campanian, well before the end-Cretaceous crisis, might have been related to competition with emerging blunt-toothed globidensine and prognathodontine mosasaurs.

Redescription of the enigmatic myriapod Hanseniellachilensis (Hansen, 1903) (Symphyla, Scutigerellidae) based on scanning electron microscope images of Chilean specimens.

Hanseniellachilensis is the only myriapod of the class Symphyla known from Chile. This garden centipede, or pseudocentipede, was described more than 120 years ago based on morphologically incomplete specimens collected in central Chile, a well-known biodiversity hotspot. In this study, we redescribe this species based on morphologically complete specimens collected near the type locality using scanning electron microscope images. Our study provides the description of diagnostic characters hitherto unknown in this species such as macrochaetae of the tergites and spinnerets of the cerci. We also include a new record from central Chile and discuss the presumed presence of this species in Argentina and Madagascar.

The Power and Performativity of Naming

In 1906, the Mikado pheasant, an endemic bird of Taiwan, was discovered as a new species by a British collector. As the creation of this new species was based solely on the examination of tail feathers, it generated excitement among ornithologists and aviculturists, sparking a series of expeditions to collect complete specimens. By following the trajectory of these endeavors and subsequent attempts to reclassify, propagate, and protect the bird, this article explores the power and performativity of scientific naming in both global and colonial contexts. The act of writing and publishing a species description is performative in that it creates a new species by assigning a scientific name that allows it to gain recognition within the scientific community and beyond. It also served to create and maintain the ornithological community—the idealized virtual community of ornithologists, bird collectors, and aviculturists. The history of the Mikado pheasant is part of a larger scientific effort to establish the comprehensive knowledge of the family Phasianidae, which motivated aspiring Japanese ornithologists to exert their acquired knowledge over the avifauna of the Japanese empire. These processes interacted during a time when zoological nomenclature was becoming accessible to non-Western zoologists. The discovery of the Mikado pheasant was the result of a colonial enterprise involving the British and Japanese empires, which converged on the interior of Taiwan and involved the Indigenous people who had settled in the mountain regions. The enduring legacy of the Mikado pheasant’s naming still resonates today.

Pirumosphaera armandae nov. sp., a new Southern Ocean polycystine radiolarian genus and species

This paper describes a new monospecific polycystine radiolarian genus and its single species so far, Pirumosphaera armandae, found in the Southwest Pacific and Indian sectors of the Southern Ocean. The new spumellarian form is rarely found as a complete specimen, as only its first and second shells are commonly found. However, partially complete specimens suggest that the test of this species is made of four shells. The most diagnostic feature of the species is the peculiar shape of the first shell which protrudes through the second shell, a characteristic that does not conform to any other Quaternary spumellarian genus. Based on the distinct and unique relationship between the first and second shells, the species is assigned to the newly established Pirumosphaera genus.

Analysis of the Fracture Characteristics and Crack Propagation Mechanism of Fractured Sandstone under Dynamic Loading

In order to study the impact of fracture thickness on the dynamic mechanical properties of rock specimens, impact compression tests on prefabricated sandstone specimens with different fracture thicknesses and intact specimens were carried out by using a split Hopkinson pressure bar (SHPB) test device, and the dynamic mechanical parameters of the fractured sandstone specimens were obtained. The results showed that the dynamic stress–strain curves of the prefabricated fractured sandstone specimens are similar to those of the intact sandstone specimens, which can be divided into three stages: elasticity, plasticity, and failure. With the increase in the thickness of prefabricated cracks, the dynamic compressive strength of the sandstone specimens decreases in a quadratic function, the dynamic strain decreases in a power exponential function, and the dynamic elastic modulus decreases linearly. Attempts were made to quantitatively analyze the crushing degree of sandstone specimens. The average particle size of the crushed specimens was negatively correlated with the thickness of prefabricated cracks, and the fractal dimension was linearly negatively correlated with the dynamic compressive strength. The 1.5–2.5 mm prefabricated fractured sandstone specimens produced airfoil cracks and secondary cracks; the 3–3.5 mm prefabricated fractured specimens produced airfoil cracks, coplanar secondary cracks, and secondary oblique cracks; and the complete specimens were subjected to axial failure to produce axial cracks.

Developing a phantom for simulating robotic-assisted complete mesocolic excision using 3D printing and medical imaging

BackgroundRobotic-assisted complete mesocolic excision is an advanced procedure mainly because of the great variability in anatomy. Phantoms can be used for simulation-based training and assessment of competency when learning new surgical procedures. However, no phantoms for robotic complete mesocolic excision have previously been described. This study aimed to develop an anatomically true-to-life phantom, which can be used for training with a robotic system situated in the clinical setting and can be used for the assessment of surgical competency.MethodsEstablished pathology and surgical assessment tools for complete mesocolic excision and specimens were used for the phantom development. Each assessment item was translated into an engineering development task and evaluated for relevance. Anatomical realism was obtained by extracting relevant organs from preoperative patient scans and 3D printing casting moulds for each organ. Each element of the phantom was evaluated by two experienced complete mesocolic excision surgeons without influencing each other’s answers and their feedback was used in an iterative process of prototype development and testing.ResultsIt was possible to integrate 35 out of 48 procedure-specific items from the surgical assessment tool and all elements from the pathological evaluation tool. By adding fluorophores to the mesocolic tissue, we developed an easy way to assess the integrity of the mesocolon using ultraviolet light. The phantom was built using silicone, is easy to store, and can be used in robotic systems designated for patient procedures as it does not contain animal-derived parts.ConclusionsThe newly developed phantom could be used for training and competency assessment for robotic-assisted complete mesocolic excision surgery in a simulated setting.

Experimental study of uniaxial compressive mechanical properties of rough jointed rock masses based on 3D printing

Abstract Roughness and inclination are important factors affecting the strength and deformation properties of jointed rock masses. Serrated joint specimens with varying joint roughness coefficient (JRC) and inclination angle were manufactured by 3D printing technique and cement mortar material. Then, uniaxial compression tests were performed for serrated joint specimens. The results show that when inclination angle equals 0° or 90°, the stress–strain curves of serrated joint specimens with various JRC values are basically the same and display a similar variation trend as that of the complete specimen, hence JRC presents a very little impact. When inclination angle varies from 30° to 60°, the stress–strain curves display a significant difference for various JRC values. Both the compressive strength and peak strain increase with the JRC value. With the increase in JRC value, the stress–strain curve exhibits a stress drop point, and with the further increase in JRC value, the stress drop point obviously delays or disappears directly. Variation in uniaxial compressive strength and deformation modulus with inclination angle is approximately U-shape for serrated joint specimens and displays typical anisotropic characteristics. Due to the variation in inclination angles and JRC values, failure modes of serrated joint specimens under uniaxial compression varies from splitting tensile or shear slip failure to compound tensile and shear failure. Rough serrated joint has a strengthening effect on the resistance ability to vertical load, and large roughness can effectively slow down the shear slip failure of jointed rock masses.

New Limaiinae (Neuroptera: Chrysopidae) from the early Eocene Fur Formation, Denmark, including an unexpected finding of a Mesozoic genus.

Two species of Limaiinae (Chrysopidae) are described from the early Eocene Fur Formation of Denmark: Mesypochrysa nielseni sp. nov. and Limaiinae gen. et sp. A. All forewing character states of M. nielseni sp. nov. are similar to those of the widely distributed Mesozoic genus Mesypochrysa Martynov, 1927, which was formerly known from the Middle Jurassic to mid-Cretaceous. Limaiinae gen. et sp. A is represented by an incomplete forewing. Although it differs from other species known from the formation, we refrained to name it pending a more complete specimen. The relatively high diversity of Limaiinae in the early Eocene of Denmark, with at least by two genera and four or five species is surprising. This diversity in the Fur Formation is nearly equal to that of Nothochrysinae.