Portion Of Wall Research Articles

PECULIARITIES OF ANLAGE AND DEVELOPMENT OF THE CERVICAL ORGANS DURING EMBRYONIC PERIOD OF HUMAN ONTOGENESIS

Objective: to determine the peculiarities of anlage and development of certain cervical organs during the embryonic period of human ontogenesis.Materials and methods. The study was conducted on 12 series of successive histological sections of the human embryos 4-6 weeks of development (4,0-13,5 mm of the parietal-coccygeal length (PCL). Only those cases were included into the study when a cause of death was not associated with pathology of the organs, vessels and nerves of the neck. The methods of preparation of series of successive histological sections, common and thin dissection under control of binocular lens, graphic and plastic reconstruction, microscopy, and morphometry were used.Results. In the embryos 4,0-4,5 mm long the rudiments of the esophagus, larynx and trachea are determined as pharyngeal derivatives on the level of the first cervical vertebra, although none of the morphological structures that can be used to determine the borders between the rudiments of the respiratory and digestive tubes are found. In front of the rudiments of the respiratory and digestive systems there are big rudiments of the heart and liver, and behind – the rudiments of the cardiac veins, dorsal aorta and vertebral column.During the fifth week of the embryonic development the rudiment of the oral pharynx is in the form of a dilated anterior part of the foregut. The oral fossa which is the initial portion of the oral pharynx is bounded above by the unpaired frontal process, lower – by paired mandibular processes, and from the sides – by maxillary processes. The cervical part of the vertebral column is located dorsally from the rudiment of the pharynx, the larynx rudiment – ventrally, and vascular-nervous bundle of the neck – ventrolaterally. The rudiment of the larynx looks like an oval accumulation of mesenchyme developed due to the closure and separation of the epithelial channel from the ventral wall of the anterior intestine. The fourth brachia arteries are determined on the examined stage of the intrauterine development transformed in the right into the anonymous artery, and in the left – into the aortal arch.In the embryos 9,0-12,0 mm of PCL in the caudal portion of the anterior pharyngeal wall on the level of branching of the tracheal rudiment there is a paired thickening of the mesenchyme in the form of arytenoid rollers with dorsally directed incisures and a transverse roller separating the entrance into the respiratory tube. The epiglottis rudiment is also determined. The venous system of the cervical region is presented by the anterior cardinal veins mainly located ventrally from the vertebral column. The junction of the anterior and posterior cardinal veins results in the formation of the common cardinal veins. At the end of the embryonic period of development the internal and external jugular veins are formed from the cranial portion of the anterior cardinal vein.Conclusions. At the end of the embryonic period of development the pharynx and trachea are not separated clearly, since they are surrounded by the common layer of mesenchyme. The larynx is presented by mesenchyme thickening located directly close to the entrance into the respiratory tube. The main cervical veins are formed from the anterior cardinal veins.

Right to Left Crossed Fused Renal Ectopia: An Incidental Finding in Cadaveric Dissection

Development of the kidney begins in the sacral region during the 4th week of gestation. As the development progresses, kidneys ascend to reach their adult position in the upper portion of the posterior abdominal wall. During the complex process of ascension, several different congenital anomalies have been shown to develop.Congenital urinary tract and renal malformations are not uncommon. One such anomaly is the fusion of the kidneys during the early embryonic period called crossed fused renal ectopia (CFRE). CFRE is a rare type of congenital malformation where both kidneys are situated on one side of the midline. In about 90% of cases, the crossed ectopic kidney is fused with the normally placed contralateral kidney. Prevalence of CFRE is estimated to be 1:1300 to 1:7500 (Turkvatan et al 2009, Bauer SB 2002). This anomaly is usually detected as incidental finding as it is often asymptomatic.We present a case of a crossed fused renal ectopia (CFRE), discovered by freshman medical students during a cadaveric dissection in a gross anatomy course at the University of Arkansas for Medical Sciences (UAMS). The body donor was a middle‐aged Caucasian female whose death was attributed to natural causes. In this case, the right kidney was positioned inferiorly and transversely fused with the lower pole of the left kidney, resulting in a single fused L‐shaped kidney (MC Donald and MC Clellan, 1957) at the gross level. The renal vascular supply was also unusual. The left renal artery arose from the normal position as a lateral branch of the abdominal aorta. Whereas, the right ectopic kidney was supplied by three arterial branches: a branch from the anterior aspect of the abdominal aorta, a second branch from the left common iliac artery and a third branch from the point of bifurcation of the abdominal aorta. In addition, the inferior mesenteric artery arose from the abdominal aorta at a much higher level than normal. It was at the level of the L1/L2 intervertebral disc. The ureteric openings in the bladder were more inferior than usual. Several small cysts were found on the kidney surface and microscopic examination of a biopsy samples from the ectopic right kidney revealed nephrosclerosis.CFRE with vascular anomalies can be clinically confusing as it would give rise to symptoms in the lower abdomen rather than in the loin. As such, surgeons who encounter this during abdominal procedures need to be aware of the multiple aberrant arteries that can make vascular control a challenge.Support or Funding InformationSupportTwo UAMS Departments: a) Neurobiology and Developmental Sciences, b) PathologyThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

MHD mixed convection and entropy generation of nanofluid in a lid-driven U-shaped cavity with internal heat and partial slip

This contribution simulates the impact of partial slip on entropy generation due to magnetohydrodynamic, mixed convection of nanofluids in a lid-driven U-shaped cavity with discrete heating. The influence of the partial slip effect is proposed along the lid-driven vertical walls. A uniform heat flux source on the bottom wall is proposed; meanwhile, the two portions of the outer-upper horizontal walls are cooled isothermally. The remainder cavity walls are taken adiabatic. The governing equations are solved using the finite volume approach, and the outcomes are successfully validated against previous studies. Simulation results are presented and discussed for several cases with the impacts of the governing parameters on the heat transfer rate. Inspection of the results in mixed convective and entropy generation environments demonstrate that the average Nusselt number increases with the increase in the volume fraction of nanoparticles at AR = 0.1. For all values of D (heat source location), the Nusselt number increases by crossing the heat source and reaches its maximum value at the end of the source. Also, for all values of the aspect ratio, addition of nanoparticles into the base fluid leads to a loss in the thermal performance. Moreover, for all states of movement, addition of nanoparticles into the base fluid leads to an increase in the entropy.

Stress Strain Speckle‐Tacking Segmental Analysis Reveals Early Indications of Diastolic Dysfunction in a Type 2 Mouse Model of Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is becoming increasingly common, as there are currently 23.1 million people diagnosed and another 84.1 million adults diagnosed with pre‐diabetes in the United States alone. While many long‐term consequences are associated with T2DM, the leading cause of mortality is cardiovascular complications. Though reduction in ejection fraction and fractional shortening are well‐described indicators of cardiovascular dysfunction, these indices are usually present late in the progression of the pathology. Identification of predictors that can be observed earlier in the disease progression may aid in diagnosing and predicting future health outcomes for the patient. The goal of the current study was to evaluate cardiac contractile changes in a rodent model of type 2 diabetes mellitus using the well characterized db/db model mouse model. Db/Db FVB mice and wild‐type (WT) littermate controls were utilized for the study (WT = 22 and db/db = 14). Echocardiography, using the Vevo 2100 Imaging System, was implemented to evaluate cardiac function in both groups at 12 weeks of age. M‐mode was used for conventional measures of cardiac function, while B‐mode short and long axis images were used for stress strain speckle‐tracking analyses. In addition, Pulse Wave Doppler analyses were utilized to examine changes in flow across the mitral valve. At 12 weeks of age, db/db mice exhibit lower ejection fractions (P ≤ 0.05) and increased stroke volumes (P ≤ 0.0018) when compared to WT. Concomitantly, db/db mice presented with significant increases in both systolic and diastolic ventricular diameters and volumes, along with an increased LV mass (P ≤ 0.0001). To determine whether spatial differences in cardiac dysfunction was associated with T2DM, we assessed regional changes in cardiac function. Speckle‐tracking strain analyses revealed significant changes in radial displacement at systole in the short axis (P ≤ 0.0024) and diastole at both the short axis (P ≤ 0.033), and long axis (P ≤ 0.0001). Segmental analysis revealed that the lateral wall portion of the left ventricle, in all axes, was significantly altered during diabetic stress. In summary, echocardiography and specifically speckle‐tracking strain analysis has the potential to indicate early dysfunction of the left ventricle during the progression of type 2 diabetes mellitus through segmentally isolated cardiac function, potentially aiding in diagnosis and future outcomes.Support or Funding InformationR01 HL‐128485 (JMH), AHA‐17PRE33660333 (QAH), AHA 17PRE33660333 (QAH), and the Community Foundation for the Ohio Valley Whipkey Trust.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Case of Squamous Cell Carcinoma Transformation in Ovarian Mature Cystic Teratoma

Mature cystic teratoma (MCT) is the commonest benign tumour arising in an ovary. Malignant transformation in a MCT of ovary is exceptionallyrare, seen only in1-2% cases.The most common malignant transformation in a benign teratoma of ovary is squamous cell carcinoma. The other malignant transformations in teratoma include adenocarcinoma, melanoma and basal cell carcinoma. The patients having this malignant transformation in teratoma have a very low 5-year survival rate of 20% approximately. Here; we describe a case of advanced-stage squamous cell carcinoma arising in a mature cystic teratoma in a 34-year-old woman.This solid high grade malignancy was missed in the pre-operative imaging which showed a right adnexal mass with echogenic foci within and septations, and was reported as a dermoid cyst. The intraoperative frozen section too taken from the thin portion of the cyst wall was reported as cystic teratoma. However in the staging laparotomy,right salpingo-oophorectomy and left oophorectomy, specimen the patient was reported to have moderately differentiated squamous cell carcinoma arising in a benign mature cystic teratomawith extensive tumour necrosis with omental tumour deposits.In view of initial incomplete surgery and advanced stage, decision of completion cytoreductive surgery was taken. The patients with mature cystic teratoma with high age (post-menopausal), a size of more than 10 cm and increased serum tumour markers should be suspected to have a malignant transformation and should be investigated thoroughly.

On the Theory of Pressure Relaxation in an Underground Tank with a Damaged Wall

A study has been made of the process of pressure relaxation in a liquid-filled tank with impaired leakproofness, which is found in the ground. Assuming that the leak rate is limited by filtration characteristics of the ground surrounding the tank, the authors have constructed a theoretical model representing a linear integral equation. Here, the obtained equation has an exact analytical solution. On the basis of a numerical analysis of this solution, the authors have analyzed the influence of the scale of the damaged portion of tank walls, the permeability of the ground, and also the rheological properties of the liquid on the rate of pressure relaxation (decay) in the tank after its sudden pressure testing.

On Improving Full-Coverage Effusion Cooling Efficiency by Varying Cooling Arrangements and Wall Thickness in Double Wall Cooling Application

Overall cooling effectiveness was determined for a full-coverage effusion cooled surface which simulated a portion of a double wall cooling gas turbine blade. The overall cooling effectiveness was measured with high thermal-conductivity artificial marble using infrared thermography. The Biot number of artificial marble was matched to real gas turbine blade conditions. Blowing ratio ranged from 0.5 to 2.5 with the density ratio of DR = 1.5. A variation of cooling arrangements, including impingement-only, film cooling-only, film cooling with impingement, and film cooling with impingement and pins, as well as forward/backward film injection, was employed to provide a systematic understanding on their contribution to improve cooling efficiency. Also investigated was the effect of reducing wall thickness. Local, laterally averaged, and area-averaged overall cooling effectiveness were shown to illustrate the effects of cooling arrangements and wall thickness. Results showed that adding impingement and pins to film cooling, and decreasing wall thickness increase the cooling efficiency significantly. Also observed was that adopting backward injection for thin full-coverage effusion plate improves the cooling efficiency.

First in situ pXRF analyses of rock paintings in Erongo, Namibia: results, current limits, and prospects

Namibia is one of the southern African countries hosting the richest rock art heritage, with thousands of rock paintings. Although numerous studies investigated their distribution, style, and possible meaning, few are known about the materials used to perform these paintings. Our in situ study aimed at identifying the diversity of pigments and alterations of some rock paintings in the northwestern part of the Erongo (Namibia). It relies on extensive pXRF analyses of 35 figures from eight rock art sites of the area. Despite common limits of in situ pXRF analyses, the extensive number of figures analyzed and the original data treatment that we performed pioneered the first scientific analyses of the pigments from rock painting sites in the Erongo Mountains. Furthermore, the study also confirmed the presence of iron oxide pigments on a portion of wall exposed during the excavations carried out at the archeological site of Leopard Cave and of possibly datable alterations over several paintings, paving the way to future chronological analyses of past tradition of rock paintings in Central Namibia.

Immediate Augmentation of Compromised Extraction Sockets in Chronic Periodontitis Patients: 1-Year Results of a Case Series on Volumetric and Histologic Response

The present case series evaluated three-dimensional volumetric bone tissue changes and new bone formation in severely resorbed extraction sockets augmented with Bio-Oss collagen and a covering collagen membrane in nine chronic periodontitis patients. Healing was by secondary intention. After 12 months of healing, the augmentation procedure appeared not only to compensate for bone remodeling but also appeared to repair a significant portion of the buccal wall. The mineralized tissue filled the 91.49% ± 6.77% of the maximum volume for regeneration. Overall, a mean of 49.6% new bone, 27.1% residual graft material, and 23.3% connective tissue were detected.

AB161. 182. Emphysematous cholecystitis: case report on a rare, life threatening presentation

: A 78-year-old gentleman with type 2 diabetes mellitus, atrial fibrillation, chronic kidney disease and hypertension presented to the emergency department with sudden onset of severe right upper quadrant with associated vomiting. White cell count showed a leukocytosis of 24×10×9/L and a C-reactive protein of 57 mg/L. An ultrasound abdomen revealed no acute gallbladder or biliary pathology. Computed tomography of the abdomen revealed pericholecystic fat stranding, an air-liquid level within the gallbladder and gas dissecting along a significant portion of the gallbladder wall—findings consistent with emphysematous cholecystitis, grade 3 with associated perforation and small volume of portal venous gas. Our patient underwent an emergency laparotomy with cholecystectomy. Pathology examination revealed acute acalculous gangrenous cholecystitis. Our patient required a 5-day admission to intensive care unit post-operatively. Emphysematous cholecystitis was first described at autopsy in 1901 by Stolz, who characterized emphysematous cholecystitis by the presence of air within the gallbladder and/or the biliary tree in the absence of an abnormal communication between the biliary system and the gastrointestinal tract. Emphysematous cholecystitis is a potentially life-threatening anaerobic infection, is a variant of acute cholecystitis. The mortality rate for acute emphysematous cholecystitis however is 15–50%. Despite the high mortality associated with gangrene and gallbladder perforation, patients with emphysematous cholecystitis do not exhibit alarming clinical signs of sepsis, and the presenting symptoms are often nonspecific and initially indistinguishable from those of uncomplicated acute cholecystitis. Patients with diabetic neuropathy may not experience typical right upper quadrant pain and maybe present with a paucity of symptoms.

Neurenteric cysts, incidence and surgical treatment

Neurenteric cysts (NCs) of the central nervous system (CNS) are cystic congenital lesions that may occur anywhere along the neural tube. They are most common in the spinal region, in the lower part of the cervical and upper thoracic spine. Intracranial NCs occur rarely and there are only small series of patients published in literature worldwide. Microsurgical resection is the treatment of choice. We present our experience in treatment of NCs and review of literature. Seven patients with NC of CNS who were operated at the Department of Neurosurgery of Comenius University at University Hospital Bratislava within nine years (2010-2018) were included in the study. The series was retrospectively evaluated with an emphasis on symptomatology, surgery and postoperative course. In three of the seven patients, NC was localized intracranially, in the other four, NC was in the spinal canal. In three patients, a complete removal of NC was achieved (2 intracranial NC, 1 spinal NC). In other patients, a portion of the cyst wall was left to prevent the development of a postoperative neurological deficit. After surgery, the neurological symptoms were completely resolved in six patients, while in one patient, they were alleviated. In one patient, a complication occurred during the postoperatove course. There was no recurrence during the follow-up (3-111 months, mean duration 39 months). In our series of patients with intracranial and intraspinal tumors, the incidence of NC was higher than presented in the published data. Our own surgical experience has shown that complete tumor resection is not always possible for intimate adherence to the surrounding structures. Leaving atiny portion of the cyst wall allowed us to achieve good clinical results with no recurrence. Long-term follow-up of patients is required due to the risk of recurrence. However, it can already be stated that an adequate extent of resection leads to good clinical results (Tab. 1, Fig. 4, Ref. 33).

Effect of Lubrication Conditions on the Forming Limit of Deep Drawing of 6061 Aluminum Alloy Sheet

With the development of lightweight vehicles, aluminum alloy sheets are increasingly used in the automotive field. However, the aluminum alloy sheet has poor forming performance at room temperature. Therefore, how to improve the sheet metal forming performance of aluminum alloy sheet has become one of the current research hotspots. In this paper, the effects of different lubricants on the deep drawing forming properties of 6061 aluminum alloy sheets were studied by cupping experiments. The effects of lubricants on the deep drawing of sheet metal forming and the wall thickness of cups after deep drawing were explored. The results show that under the condition of drawing speed of 3MPa and 200mm/min, the ultimate drawing ratio of the sheet under oil lubrication is 1.92, and the PTFE film is 2.16. Grease and graphite lubrication are respectively 2.12 and 2.03, using PTFE film lubrication can increase by about 10% contrast with the oil lubrication. The measurement of the wall thickness of the cup under the forming limit state shows that the position with the largest reduction rate appears in the rounded transition zone, and the wall portion of the cylindrical member increases with the height of the wall, and the thickness from the bottom of the cup to the bottom of the cup. The edges all show a trend of decreasing first and then increasing.

Thermal Radiation on Mixed Convective Flow in a Porous Cavity: Numerical Simulation

Abstract In this paper, the influence of mixed convection in a porous square enclosure under the effect of radiation is numerically examined. The top and bottom walls are maintained at uniform temperature θc while some portion of the vertical walls is partially heated with temperature θh and rest of the vertical walls are thermally insulated, with θh > θc. The non-dimensional governing equations are solved by MAC (Marker and Cell) method. The effect of various parameters (thermal Grashof number, Darcy number, Prandtl number, Reynolds number) on flow patterns and heat transfer has been presented.

Analysis of risk factors of 19 fractured implants

Objective: To analyze the incidence and possible risk factors of 19 fractured implants out of 8 468 implants in 3 184 cases. Methods: During the 22-year clinical practice, clinical records of 18 patients with 19 fractured implants in 3 184 cases with 8 468 implants were analyzed to determine the following factors: location of the fractured implants, prosthodontics option, date of implant fracture, dimensions of fractured implants, complications prior to implant fracture and parafunctional habit. An evaluation of fractured implants was performed to identify possible factors that may predispose an implant to a higher risk of fracture. Results: Overall, the average duration of service of the implants was (7.0±4.5) years. Implant fracture occurred in 7 Camlog implants, 7 Nobel replace implants, 3 Ankylos implants and 2 Brånemark implants. No Thommen implant fractures were recorded. Amongst the 19 fractured implants, 8 occurred at the thinnest wall portion of the implant neck, 8 at the end of screw and 3 at the self-tapping thread region. All fractures were observed after functional loading. Furthermore, 9/19 (47.4%) of fractures occurred in the maxilla, indicating similar incidence rates in both arches (P=0.065). Most of fractures (16/19) occurred in the molar region and 18/19 in single implant-supported restorations. Totally 17 cases had received metal occlusal restorations. In 6 cases (35.5%), previous bone destruction apically extending to the level of implant fracture was documented before any clinical signs of fracture. Three fractured implants were removed and simultaneously re-implanted with larger-diameter implants, while the rest of the cases were left to heal, followed by a second-stage surgery. Conclusions: Within the limitation of this analysis, the study demonstrated that appropriate implant-abutment connection design, implant diameter, prosthetic strategy and bone resorption are crucial to the long-term performance of implants. There is no significant difference of fractures rates in both archs.

Curvature area prediction for the deep drawing-ironing process of a cylindrical cup using finite element method and regression analysis

Products with long, cylindrical or rectangular can-shaped sidewalls are manufactured using a deep drawing-ironing (DDI) process. The volume of a typical cylindrical, axisymmetric product after the DDI process can be broadly divided into bottom, curvature, and side wall portions. In sheet metal forming, the volume of a product before and after forming is easily calculated from the law of volume constancy. Cylindrical, axisymmetric products can be represented as a two-dimensional axisymmetric problem, thus converting the volume calculation to an area calculation in two dimensions. The curvature area of an axisymmetric product can be geometrically expressed using a formula obtained by subtracting the area of a circle from the area of an ellipse. However, the geometrical curvature area obtained using this formula differs from the curvature area of the real product. Therefore, in this study, a finite element analysis is performed under the same condition as the actual product to which the DDI process is applied, and the validity of the analysis is verified by comparing the data. Finally, a regression analysis is conducted on the data obtained from the finite element analysis to derive an equation to predict the curvature area. In addition, the proposed method is verified by comparing with the data pertaining to a real part.

Stability analysis of coupled structural acoustics PDE models under thermal effects and with no additional dissipation

AbstractIn this study we consider a coupled system of partial differential equations (PDE's) which describes a certain structural acoustics interaction. One component of this PDE system is a wave equation, which serves to model the interior acoustic wave medium within a given three dimensional chamber Ω. This acoustic wave equation is coupled on a boundary interface Γ0 to a two dimensional system of thermoelasticity: this thermoelastic PDE is composed in part of a structural beam or plate equation, which governs the vibrations of flexible wall portion Γ0 of the chamber Ω. Moreover, this elastic dynamics is coupled to a heat equation which also evolves on Γ0, and which imparts a thermal damping onto the entire structural acoustic system. As we said, the interaction between the wave and thermoelastic PDE components takes place on the boundary interface Γ0, and involves coupling boundary terms which are above the level of finite energy. We analyze the stability properties of this coupled structural acoustics PDE model, in the absence of any additive feedback dissipation on the hard walls Γ1 of the boundary . Under a certain geometric assumption on Γ1, an assumption which has appeared in the literature in connection with structural acoustic flow, and which allows for the invocation of a recently derived microlocal boundary trace estimate, we show that classical solutions of this thermally damped structural acoustics PDE decay uniformly to zero, with a rational rate of decay.

Transient cooling characteristics of Al2O3-water nanofluid flow in a microchannel subject to a sudden-pulsed heat flux

Transient cooling characteristics of Al2O3-water nanofluid flow in a microchannel subject to sudden-pulsed heat flux are numerically examined in details. The attention is focused on the effects of microencapsulated phase change material (MEPCM) inside top wall of a microchannel on the transient cooling heat transfer behaviour of the microchannel. Two small portion of the bottom channel wall are exposed to a pulse heat flux. The Al2O3- water nanofluid as the working fluid with a fully developed velocity profile flows into the microchannel to cool the channel walls. Transient conjugate heat transfer is studied using a three-dimensional model in the three parts of the microchannel which are the nanofluid flow, the solid walls of the channel, and the MEPCM layer. The partial differential equations governing the energy conservation are presented and transformed into a dimensionless form. The finite volume method is employed to numerically integrate the equations for the temperature distribution in the microchannel. The numerical results are compared with the available works in the literature and found in good agreement. Besides, the predictions show that the presence of the MEPCM layer cannot effectively control the rise of the temperature of the microchannel in the presence of a pulse heat flux. For a typical pulse heat flux, the bulk temperature of the channel can be raised up to 2 °C while the presence of the MEPCM layer would only suppress the temperature rise by 0.2 °C. It is also found that the temperature of the top wall is under the significant influence of the MEPCM layer. The increase of the amplitude of the heat flux pulse results in better cooling effect of the MEPCM layer.

Role of transcranial sphenoidotomy in skull base surgery: classification of surgical techniques based on the surgical anatomy of the sphenoid sinus.

Although sphenoidotomy is more commonly performed via the transnasal approach than via the transcranial approach, transcranial sphenoidotomy (TCS) remains indispensable for en bloc resection of locally advanced sinonasal malignant tumors (SNMTs) extending to the skull base. TCS also enables transsphenoidal transposition of the temporoparietal galeal flap (TPGF) to compensate for the lack of vascularized reconstructive tissue after endoscopic transnasal skull base surgery. The objective of this study was to review the authors' surgical experience using TCS with an emphasis on the surgical anatomy of the sphenoid sinus and on the purpose of TCS. Relevant anatomy is further illustrated through cadaveric dissection and photo documentation. The authors reviewed the records of 50 patients who underwent TCS at the Nagoya University Hospital, Fukushima Medical University Hospital, or Aichi Medical University Hospital over the course of 7 years (between January 2011 and November 2017). The authors also performed cadaveric dissection in 2 adult cadaveric skull base specimens. Of the 50 patients included in this study, 44 underwent craniofacial resection (CFR) for en bloc resection of SNMTs involving the anterior and/or lateral skull base, and 6 underwent transsphenoidal transposition of the TPGF flap. The authors categorized the TCS procedures according to the portion of the sphenoid sinus wall involved (i.e., superior, lateral, and superolateral). Superior sphenoidotomy was used in patients requiring anterior CFR. Lateral sphenoidotomy was further divided into 2 subtypes, with type 1 procedures performed for the transsphenoidal transpositioning of the TPGF, and type 2 procedures used in patients requiring lateral CFR. Superolateral sphenoidotomy was used in anterolateral CFR. TCS still represents a useful tool in the armamentarium of neurosurgeons treating central skull base lesions. The newly proposed surgical classification facilitates a profound understanding of TCS and how to incorporate this technique into clinical practice.

The detrimental effect of autofrettage on externally cracked modern tank gun barrels

Overstraining gun tubes has a twofold advantage. First, it enables the increase of the Safe Maximum Pressure (SMP) in the tube, resulting in a higher muzzle velocity which extends the gun's range and its projectile kinetic energy. Second, it reduces the tube's susceptibility to internal cracking which prolongs its fatigue life. Unfortunately, autofrettage also bears an inherent detrimental effect as it considerably increases the tensile hoop stress at the outer portion of the barrel's wall, which enhances external cracking of the tube by increasing the prevailing Stress Intensity Factor (SIF). In order to quantify this disadvantageous effect, 3-D Mode I SIFs distributions along the front of a single external radial semi-elliptical crack initiating from the outer surface of an autofrettaged modern gun barrel, overstrained by either the Swage or the Hydraulic autofrettage processes, are evaluated. The analysis is performed by the finite element (FE) method, using singular elements along the crack front. Innovative residual stress fields (RSFs), incorporating the Bauschinger effect for both types of autofrettage are applied to the barrel. Hill's [1] RSF is also applied to the tube for comparison reasons. All three RSFs are incorporated in the FE analysis, using equivalent temperature fields. Values for KIA - the SIF resulting from the tensile residual stresses induced by autofrettage are evaluated for: a typical barrel of radii ratio Ro/Ri = 2, crack depth to wall-thickness ratios (a/t = 0.005–0.1), crack ellipticities (a/c = 0.2–1.0), and five levels of Swage, Hydraulic and Hill's autofrettage (ε = 40%, 60%, 70%, 80%, and 100%). In total, 375 different 3-D cases are analyzed. The analysis demonstrates undoubtedly the detrimental effect of all types of autofrettage in increasing the prevailing effective stress intensity factor of external cracks, resulting in crack initiation enhancement and crack growth rate acceleration which considerably shortens the total fatigue life of the barrel. Nonetheless, the detrimental effect is autofrettage-type dependent. Swage and Hydraulic autofrettage RSFs differ substantially from each other. The disadvantageous effect of Swage autofrettage is much greater than that resulting from Hydraulic autofrettage. The results also emphasize the significance of the Bauschinger effect and the importance of the 3-D analysis.

Understanding conflagration of one-story mud-brick structures: an experimental approach

Many Near Eastern destruction layers are characterized by burnt, partially collapsed, mud-brick structures. Despite the prominence of these layers in archaeological field research, the processes that generated these layers are little understood. In order to explain field observations and identify patterns that may be useful for archaeological interpretation, experimental burning of miniature single-story mud-brick structures was conducted. Two types of structures—covered by vegetal roofs or by mud-plastered roofs—were conducted. Each experiment was duplicated. Temperatures in chambers, walls, roofs, and floors were recorded continuously. Bricks, floor, and roof sediments were sampled and analyzed by Fourier transform infrared (FTIR) spectroscopy after the burned structures cooled down. The results showed that ignition of vegetal roofs does not produce a pattern recognizable in Near Eastern destruction layers, while chamber ignition within mud-plastered roofed structures produces patterns that most resemble field evidence. These include (a) upper portions of walls and mud roofs witness temperatures above 500 °C resulting in a mineralogical change that is identifiable by FTIR, (b) no significant heat in floor deposits, (c) higher temperatures in upper parts than the bottom portions of walls, (d) external walls experience heat diffusion to the outside environment and do not burn through, and (e) internal walls can burn through. The directly measured temperatures correlate with reconstructed temperatures via FTIR and with brick color patterns. Future field research should explore color patterns in cross-sections of mud-brick walls and apply FTIR spectroscopy to reconstruct distribution of heat across destruction levels.