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•The attempt of building FEA model dedicated to damage prediction.•Comparison of PFA and experimental damage evaluation in 1:1 macro- and microscale.•Analysis of ply stacking sequence ...effect on damage initiation and propagation.•Ply clusters reduce delamination range at the expense of intense crack development.•PFA model predicts well the localization of damage onset but not the damage types.
Fibre reinforced polymers are widely used materials in terms of their mechanical properties. The application of proper stacking-sequence of layers allows to obtain desirable properties of composite structure, and affect its failure mechanisms. The aim of this work was to evaluate the stacking sequence influence in the axially compressed glass-fibre reinforced epoxy thin-walled columns. To highlight the differences, the comparative failure analysis was performed. The macroscopic observation and the analysis of X-ray µCT images presented numerous damage types for particular stacking sequences. Also, the progressive failure analysis model, which takes the manufacturing conditions into account, was implemented. The novelty of the analysis approach lies in direct comparison of experimental and numerical results in scale 1:1 – both in macroscale and microscale. The analysis indicated the most sensitive points of the studied columns in terms of damage initiation. The most dominant failure mode was delamination. It was noted ply clustering allows one to limit the damaged area in cost of increased matrix failure. It was also noticed that symmetric and asymmetric stacking sequences possess insignificant differences in the damaged area. The changes of stacking sequences have the effect on the development of translaminar, interlaminar and intralaminar cracks likewise. The comparison of experimental failure analysis and finite element method showed that the PFA model predicts the approximate localization of the failures.
Brain cutting and trimming Iwasaki, Yasushi
Neuropathology,
October 2022, Letnik:
42, Številka:
5
Journal Article
Recenzirano
The process of brain cutting followed by trimming is quite important to make adequate specimens for sufficient neuropathological observations. The protocol described herein is recommended as an ...optimized implementation for suitable preparation, which inevitably leads to an accurate neuropathological diagnosis. To obtain neuropathological cues, macroscopic observation of the brain before cutting presents an important opportunity. Gross examination provides a clue to the neuropathological diagnosis and shows clinicopathological correlations. Brain cutting should be preceded by a careful review of the clinical notes and consideration of the possible pathological diagnosis. Therefore, the medical staff associated with the patient should attend the procedure to provide clinical information. The process involves removing the brainstem and cerebellum from the cerebrum, sectioning the cerebrum, removing the cerebellum from the brainstem, and sectioning the cerebellum, brainstem and spinal cord followed by trimming. Trimming should be performed in accordance with the internationally accepted guidelines for the pathological diagnosis of different types of neurodegenerative diseases. In each stage acquiring clear photographs is significant, the observations must be concisely recorded, and which side of the specimen is to be sliced and stained has to be indicated. Additionally, it is necessary to photograph all trimmed tissues to assist with orientation of the brain in later assessments. The three‐dimensional structure and individual differences have to be considered. These skills are essential, and knowledge of neuropathology, neurology and neuroanatomy is required for appropriately cutting and trimming of the brain.
Satellites in low Earth orbit (LEO) are subject to several environmental factors, atomic oxygen (AO) having the greatest effect on space materials, especially polymers. Recently, the possibility of ...utilizing orbits at an altitude lower than 300 km (super LEO or S-LEO) has been explored, but one complication in using these orbits is that AO fluence is expected to far exceed that in an ordinary LEO. The effect of S-LEO AO on materials used in space is not well understood. To investigate the influence of S-LEO AO on space materials, we developed the Material Degradation Monitor (MDM), which is installed on a JAXA spacecraft, the Super Low Altitude Test Satellite (SLATS, also known as TSUBAME). The SLATS is the first S-LEO satellite to operate at an altitude under 200 km and the MDM is the first near real-time experiment to examine the effects of AO on materials in this orbit. The aim of the MDM is to clarify degradation behaviors of the space materials according to AO fluence. We developed the instruments needed to detect AO fluence and the changes it causes to samples of various materials in S-LEO. The MDM performed as expected until the end of the SLATS operation. Some changes in materials were found from the images taken from front and back LEDs. Although there was no breakage by AO, optical properties changed that are assumed to be due to material erosion by AO.
•The super-low altitude test satellite was demonstrated at an altitude under 200 km.•A near-real-time space material monitoring system was designed for the satellite.•Material-degradation images that show change with time were successfully acquired.•The behaviors of the materials on exposure to atomic oxygen can be analyzed.
It has been confirmed that nanofibrous poly（3-hydroxybutyrate-co-3-hydroxyvalerate） nerve conduit can promote peripheral nerve regeneration in rats. However, its efficiency in repair of over ...30-mm-long sciatic nerve defects needs to be assessed. In this study, we used a nanofibrous poly（3-hydroxybutyrate-co-3-hydroxyvalerate） nerve conduit to bridge a 30-mm-long gap in the rat sciatic nerve. At 4 months after nerve conduit implantation, regenerated nerves were macroscopi- cally observed and histologically assessed. In the nanofibrous graft, the rat sciatic nerve trunk had been reconstructed by restoration of nerve continuity and formation of myelinated nerve fiber. There were Schwann cells and glial cells in the regenerated nerves. Masson＇s trichrome staining showed that there were no pathological changes in the size and structure of gastrocnemius muscle cells on the operated side of rats. These findings suggest that nanofibrous poly（3-hydroxybutyrate-co-3- hydroxyvalerate） nerve conduit is suitable for repair of long-segment sciatic nerve defects.
This study has reviewed the last two decades of student conception research in solution chemistry pertaining to aims, methods of exploring students' conception, general knowledge claims, students' ...conceptions and difficulties, and conceptual change studies. The aims of solution chemistry studies have been to assess students' understanding level of solution chemistry and in some studies compare understanding based on age and year at school or college. The methods of exploring students' conceptions consisted of interviews, paper and pencil surveys (open-ended questions and multiple-choice questions), free writing and drawings and the validity of these methods have been highlighted. The general knowledge claims synthesized in this study are students' (a) attending to mechanical events, (b) preference for everyday language usage over chemical language, (c) confusing solution chemistry with non-related concepts, (d) lack of sub-microscopic explanation for macroscopic observation, (e) difficulty with visualizing and representing sub-microscopic ideas, (f) difficulty with symbolic representations, (g) inconsistent explanations, (h) development of student understanding with age, and (i) development of conservation reasoning with age. To incorporate students' conceptions, conceptual change studies have used strategies such as worksheet, analogy, collaboratively working with a teacher, hypermedia, and group exploration. The results of conceptual change studies generally have had a positive impact enabling students to consider their ideas and develop plausible models of solution chemistry. For improvement of student learning in chemistry, this review of solution chemistry studies sheds light on teacher thinking and capacity building with respect to explicitly incorporating students' conceptions into chemistry curriculum; practicing research-based strategies; forging links among types of chemical knowledge; collaborating for experimental teaching; and conducting further research.
Based on my personal experience publishing case reports on blunt injuries, I hereby focus on issues that have recently come to my attention. 1. Abrasions: 1) As to whether they occurred ante-mortem ...or post-mortem; those reddish in color cannot always have occurred antemortem. When they overlap with reddish (-purple) discoloration, as in hypostasis, post-mortem abrasions look reddish as well. Abrasions larger than the tip of the finger or the palm of the hand are often seen post-mortem and are thought to occur due to the touching of putrefied skin post-mortem. 2) There are cases where the direction in which the epidermis peeled-off is not apparent, when it peels off in many directions or where there is no residual epidermis. 3) The shape and size of an abrasion can indicate the structure of the offending blunt object. When there is an abrasion on the scalp 3 to 4 cm in diameter, with structures 5 mm in diameter at the margins of the abrasion, it can be inferred that the victim fell on a paved gravel road. 2. Bruises: 1) Inferring the nature of a blunt object: (1) Evidence of a fist blow: Co-existence of the following three features indicates a blow by the fist : 1. macular discoloration, 2. within an area of approximately 8 cm by 5 cm, 3. with an abrasion from the thumb nail. (2) Evidence of being grabbed:Try to grab the corpse with your own hand during autopsy to find how the person was grabbed. Bruise-like discoloration can be generated post-mortem on the upper arm, when a body is being drawn out of water, for example. 2) Tram-line bruises: These appear when a victim was struck by a stick. To estimate the diameter of the object, it is useful to measure two parts of the bruising : the width of the pale part between the bruises and the width between the outer margins of the bruises. 3. Intradermal bleeding: There tends to be a grouping of hemorrhagic spots, the interval between which 1 mm or less. It can be generated by both direct and indirect force. Abrasions may be both present or absent. 4. Contused lacerated wounds: First of all, it is necessary to determine the characteristics of the offending blunt object based on the findings of the wound. When the edge of the end of a column works against the skin at an angle, abrasions are mainly generated on the one margin abraded by the edge. When the smooth round surface of a column is applied, abrasions are not likely to occur on or near the margins. To diagnose a wound as being contused, the following findings are considered valuable : the margins of the wound are more irregular than the incision; the margins are contused; the osseous membrane is detached at the bottom of the wound; and abrasions are present at the margins. Abrasions are generated when the surface of the object is rough and when the sharper edge is at an angle. They tend not to occur when the surface of the object is smooth with no angular edge or when the sharper edge works perpendicularly against the skin. 5. Post-mortem mutilation by animals: It is necessary to distinguish wounds caused by animals from those that are man-made. Crows will tear out the eyeballs, open the intercostal muscle and devour the lungs. They pull and rip off the skin, but do not seem to chew on the bones. Dogs and foxes will chew on the bones, leaving traces of their teeth about 5 mm in width. Rats leave round-shaped parts missing from the skin, the margins of which are quite sharp. They do not seem to chew on the bones. 6. One pattern of injuries from an immersed body: A set of abrasions, bruises, pocket formation (décollement) of the head and face, accompanied by dehiscence or fracture of the spine and drowning indicates jumping into the water face first and banging the head against the bottom of the body of the water, followed by drowning. 7. A case of a traffic accident: The details of the accident became apparent from the following findings in and on the autopsied body: contused lacerations on both knees, abrasions and pocket formation (décollement) on the parietal region of the head, characteristically shaped abrasions on the back, acetabula fractures caused by raising of the femoral head, fractured ribs caused by antero-posterior or posteroanterior compression, and an annular fracture at the base of the skull. The abrasions on the back were determined to have been generated by compression of structures on the underside of the car. The contused lacerations on the knees were considered to have been generated upon impact with the bumper, and the posture of the victim was concluded to have been supine with his knees drawn up. Collaboration with police traffic investigators is considered essential. 8. The medico-legal diagnostic capability of young pathologists could be improved if they observed unexplainable findings during autopsy with their own eyes, researched and discussed the findings with their mentor and colleagues, and published case reports.
Intermediate morphologies between normal and anomalous morphologies of the superior belly of the omohyoid muscle (Om) were macroscopically and stereomicroscopically observed in 34 cadavers (24 males ...and 10 females aged between 51 and 97 years; average age 71.0 years) for anatomical practice, which had been preserved in the Department of Morphological Biology, Ohu University School of Dentistry. The intermediate morphologies were classified into four types on the basis of the developmental degree of the muscle fibers and the number and origin of the belly as follows: type 1, the anterior margin of the belly was unclear owing to poor myofiber development; type 2, the superior belly was composed of a posterior large belly and an anterior small belly; type 3, composed of three to five bellies, with the bellies arranged in a roof tile‐like morphology; and type 4, the belly was composed of two bellies arranged anterior–posteriorly parallel to each other (the anterior belly was found to be the inferior belly that had developed and reached the superior belly area). For the intermediate morphologies of the Om superior belly observed in the present study, although type 4 was due to the development of an inferior belly, the other three types were considered to be caused by the poor development of the myofibers in the formation process and by the division of the superior belly into two muscles, or secondary lamellar division of the belly with growth.
This study was performed to determine if, as expected, the enlarged eye of the Baikal seal (Phoca sibirica) has an influence on the form and function of the skull and facial muscles. Macroscopic ...observation of these muscles demonstrated that the M. orbicularis oculi expands around the palpebral fissure and that some facial muscles attach and insert in the M. orbicularis oculi, possibly supporting M. orbicularis oculi function. We suggest that these muscles move the eye and palpebral area and constitute a morphological and synergistic facial muscle complex system. Further, the development of the M. rectus lateralis around the sclera of the eye indicates that this muscle is also involved in eye movement.
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