Enlargement Of Defects Research Articles

High-temperature oxidation degradation mechanism of novel Zr-containing SiC fibers

The application of ceramics matrix composites (CMCs) in extreme environments is often dictated by the oxidation resistance of SiC fibers, which are frequently utilized as the reinforcement of CMCs. Introducing heterogeneous elements into SiC fibers is one effective way to enhance their oxidation resistance. In this work, the chemical composition, microstructural evolution, phase evolutions, and tensile strength of the newly developed Zr-containing Zeralon 200™ SiC fiber oxidation-treated at elevated temperatures in an air atmosphere for 5 h was investigated in depth, using transmission electron microscope (TEM), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscope (EDS), field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), and Raman spectroscopy (Raman). Results indicate that the Zeralon 200™ SiC fiber has a significantly better oxidation resistance than some typical non-heterogeneous element SiC fibers. ZrSiO4 was found to generate in the fiber after oxidation treatment at 1100 °C for 5 h. The specific generation mechanism of ZrSiO4 and its oxidation resistance mechanism in the Zeralon 200™ SiC fiber were revealed. Meanwhile, the degradation mechanism of the tensile strength of Zeralon 200™ SiC fiber was discussed in detail. In short, the decline in the tensile strength of Zeralon 200™ SiC fiber can be ascribed to the decomposition of the amorphous phase SiCxOy, the enlargement of defects within the fiber bulk, and the decrease in the effective load-bearing cross-sectional area of the fiber caused by extensive oxidation, sequentially occurring at various elevated temperatures.

Improved Soft Magnetic Properties in FeNi@MgO Composites by Sol-Gel-Based Surface Coating and High-Temperature Heat Treatment

In this study, we utilized MgO as an insulating buffer layer to enhance the thermal stability and soft magnetic properties of Fe-Ni soft magnetic composites (SMCs) and investigated the effect of high-temperature heat treatment on those soft magnetic properties. By employing the sol-gel process, a uniform MgO insulating layer with a thickness of 600 nm was coated onto Fe-Ni magnetic powder. Subsequently, high-density SMCs were fabricated through high-pressure compaction molding. The MgO layer remained intact up to 800 °C, leading to the FeNi@MgO@MK SMCs exhibiting enhanced permeability and reduced hysteresis loss due to grain enlargement and elimination of defects, such as dislocation stacking. Notably, the dynamic loss increase after high-temperature heat treatment was significantly regulated compared to the case of the uncoated counterpart. The results underscore the potential to improve the thermal stability and soft magnetic properties of MgO-coated Fe-Ni SMCs, rendering them suitable for various electromagnetic applications.

An individualised approach to reduce trocar site hernia

In systematic reviews, the calculated pooled prevalence of trocar site hernia (TSH) has been estimated at 0.5%. Increasing age, high body mass index, smoking, and wound infection potentially influence the incidence. Increasing trocar size, retrieval of specimens through trocar sites, excessive force used in manipulation of the trocar and frequent re-insertion of the trocar may also play a role in the enlargement of the muscolofascial defects. This paper reports a case of a Richter’s hernia within a 5 mm abdominal port site occurring in the early post operative period following laparoscopy. This is significant because it is an uncommon complication of a common procedure. We highlight that various factors may increase the likelihood of this uncommon condition, and provide a brief overview of TSHs.

Mechanics and Dynamics of Bacterial Cell Lysis

Membrane lysis, or rupture, is a cell death pathway in bacteria frequently caused by cell wall-targeting antibiotics. Although previous studies have clarified the biochemical mechanisms of antibiotic action, a physical understanding of the processes leading to lysis remains lacking. Here, we analyze the dynamics of membrane bulging and lysis in Escherichia coli, in which the formation of an initial, partially subtended spherical bulge (“bulging”) after cell wall digestion occurs on a characteristic timescale of 1 s and the growth of the bulge (“swelling”) occurs on a slower characteristic timescale of 100 s. We show that bulging can be energetically favorable due to the relaxation of the entropic and stretching energies of the inner membrane, cell wall, and outer membrane and that the experimentally observed timescales are consistent with model predictions. We then show that swelling is mediated by the enlargement of wall defects, after which cell lysis is consistent with both the inner and outer membranes exceeding characteristic estimates of the yield areal strains of biological membranes. These results contrast biological membrane physics and the physics of thin, rigid shells. They also have implications for cellular morphogenesis and antibiotic discovery across different species of bacteria.

CLINICAL ASSESSMENT OF ORAL DEBRIDEMENT AND TEETH BLEACHING SAFETY IN PATIENTS WITH TEETH ABFRACTIONS AND GINGIVAL RECESSION

Introduction. The most of dental practitioners have some doubts about teeth bleaching safety in patients with teeth abfractions and gingival recession. Aim. Assessment of professional oral debridement and teeth bleaching safety in patients with teeth abfractions and gingival recession. Material and methods. Randomized controlled trial was done in two groups of 30 patients with teeth abfractions and gingival recession. In group 1 oral debridement and professional dental bleaching were performed. Abfractions and recessions were isolated with a liquid dam. In group 2 oral debridement was made. The vertical size of recession, Tooth Wear Index and Schiff air sensitivity index were evaluated. Results. After 12 months the enlargement of wedge defects was pronounced in 5 teeth in group 1 and in 7 teeth in group 2. The enlargement of the gingival recession was marked in 6 teeth in group 1 and in 8 teeth in group 2. No statistical difference between groups was seen. In group 1 after teeth bleaching the sensitivity was present in 240 teeth (40%), after 14 days amount of teeth with sensitivity reduced to 110 (18.3%). In group 2 after oral debridement, the sensitivity was present in 250 teeth (41.7%), after 14 days amount of teeth with sensitivity reduced to 239 (39.8%). Conclusion. The teeth bleaching has no effect on dental abfractions and gingival recession.

Titanium mesh cranioplasty in pediatric patients after decompressive craniectomy: Appropriate timing for pre-schoolers and early school age children

PurposeThere is little knowledge on the growth of cranial defects, appropriate timing and outcomes of application of titanium mesh for cranioplasty in the pediatric population, especially pre-school age (2–5 years old) and school age (6–12 years old) children. We hypothesised that cranioplasty for pre-schoolers could be delayed to school age due to the expected cranium growth, whereas, for the school age group, it is better to perform routine cranioplasty (3–6 months) to protect the brain and therefore ensure their timely return to school life. Materials and methodsA retrospective review of pediatric patients (2–12 years old) who underwent titanium mesh cranioplasty for cranial defects from 2006 to 2012 was performed. Patient demographic data, radiological data, and clinical information were collected. Specifically, cranial defect sizes were evaluated by three-dimensional (3D) reconstruction of computed tomography data after craniectomy, before cranioplasty and 2-years after cranioplasty. Patients were routinely followed up at an outpatient clinic for complications and school attendance. ResultsA total of 18 titanium mesh cranioplasties were performed in 18 patients. The average interval between craniectomy and cranioplasty was 3 years for pre-schoolers and 4 months for the school age group. Patients in the pre-schooler group showed significant enlargements in cranial defects during the interval as compared with the school age group (26% vs. 4%, P < 0.05). There were no surgery-related complications except in one patient, who had titanium mesh exposure 11 months later. Two years after cranioplasty, there was no significant difference in mild cranial defect enlargements between the two groups (11% vs. 6%, P > 0.05). Patients were followed for an average of 5 (range, 2–8) years. All patients had satisfactory recovery of cranial contour, sufficient protection of the brain and active participation in school study. All patients had satisfactory recovery of cranial contour, sufficient protection of the brain and active participation in school. ConclusionTiming of titanium mesh cranioplasty after decompressive craniectomy based on their age is a workable solution for school-age pediatric patients. The enlargement of cranium defects in pre-schoolers supports a delayed repair until school age. The long-term outcomes for these patients with titanium mesh cranioplasty are favourable.

Progression of lamellar hole-associated epiretinal proliferation and retinal changes during long-term follow-up

PurposeTo report on progression of lamellar hole-associated epiretinal proliferation (LHEP) in eyes with lamellar macular holes (LMH) using spectral-domain optical coherence tomography (SD-OCT), and to correlate with intraretinal changes and...

Formation of Synthetic Nanopores with Diameters from 20-50 nm by Laser-Assisted Dielectric Breakdown

Fabrication of nanopores in synthetic substrated by controlled breakdown (CBD)[1] is a robust and well characterized method that allows sub-2 nm nanopore fabrication, which is a challenge for traditional fabrication methods such as transmission electron microscopy (TEM). Due to its stochastic pore formation process, however, attempts to widen a nanopore using CBD can result in random formation of multiple nanopores instead of increasing the size of a single pore. Since CBD is a broadly-accessible, tuneable, and cost-effective method, it would be useful to fabricate nanopores with diameters from 20 to 50 nm for applications beyond DNA sequencing. This work focuses on fabricating such large nanopores by optically localizing the formation and enlargement of defects in the SiN membrane[2]. We show that the breakdown time of SiN membranes (i.e. time for dielectric breakdown at constant applied potential difference across the membranes) can be lowered significantly by focusing a laser beam on the membrane. To avoid forming multiple nanopores during the enlargement process, low voltage pulses were applied. In this study, differences of parameters between nanopores fabricated by standard CBD and laser-assisted CBD are discussed. The size, number and shape of the resulting nanopores are assessed by various techniques, including protein translocation experiments.[1] Kwok, H.; Briggs, K.; Tabard-Cossa, V. PLoS One 2014, 9, (3), e92880. [2] Pud, S.; Verschueren, D.; Vukovic, N.; Plesa, C.; Jonsson, M. P.; Dekker, C. Nano letters 2015, 15, (10), 7112-7.

Retention of sealants during orthodontic treatment: an in vitro comparison of two etching protocols.

To test the retention of smooth-surface sealants bonded with different etching protocols against toothbrushing and, secondarily, to characterize the type and location of sealant loss. Eighty-nine extracted human teeth were randomly assigned one of two etching protocols: 37% phosphoric acid etch (ETCH) or self-etching primer (SEP). Six specimens at a time were placed in a toothbrushing machine to simulate 4, 8, 12, and 24 months of toothbrush abrasion. Using black-light photographs of each specimen taken before and after brushing, four blinded coinvestigators determined new sealant loss, loss along the edge of an initial defect, and the location of sealant loss. Overall, there were significantly (P < .05) more teeth with sealant loss in the SEP group (38.6%) than in the ETCH group (15.5%). New loss of sealant was significantly (P < .05) more likely in the SEP group (27.2%) than in the ETCH group (2.2%). Of the teeth with new loss of sealant, all (100%) had loss at the edge, and 23% had progressive loss. There was no significant group difference in sealant loss from initial defects. Of the teeth that showed enlargement of initial defects, 91% had loss at the edge and 91% had progressive loss. Using SEP to apply facial sealants results in lower retention rates than using ETCH. The vast majority of sealant loss occurs at the edges. Loss of sealant due to enlargement of an initial defect is highly progressive over time.

Enlargement of Glenoid Defects in Traumatic Anterior Shoulder Instability: Influence of the Number of Recurrences and Type of Sport.

Background:Large glenoid rim defects in patients with traumatic anterior shoulder instability are often regarded as a contraindication for arthroscopic Bankart repair, with a defect of 20% to 27% considered as the critical size. While recurrence of dislocations, male sex, and collision sports were reported to be the significant factors influencing large glenoid defects, the influences of subluxations and more detailed types of sports were not investigated.Purpose:To investigate the influence of the number of dislocations and subluxations and type of sport on the occurrence and size of glenoid defects in detail.Study Design:Case-control study; Level of evidence, 3.Methods:A total of 223 shoulders (60 with primary instability, 163 with recurrent instability) were prospectively examined by computed tomography. Glenoid rim morphology was compared between primary and recurrent instability. In patients with recurrent instability, the relationship between the glenoid defect and the number of dislocations and subluxations was investigated. In addition, glenoid defects were compared among 49 male American football players, 41 male rugby players, 27 male baseball players, and 25 female athletes.Results:The mean extent of the glenoid defect was 3.5% in shoulders with primary instability and 11.3% in those with recurrent instability. A glenoid defect was detected in 108 shoulders (66.2%) with recurrent instability versus 12 shoulders (20%) with primary instability. Regarding the influence of the total number of dislocations/subluxations, the average extent of the glenoid defect was 6.3% in 85 shoulders with 2 to 5 events, 12.9% in 34 shoulders with 6 to 10 events, and 19.6% in 44 shoulders with 11 or more events. The glenoid defect became significantly larger along with an increasing number of recurrences. Although recurrent subluxation without dislocation also influenced the glenoid defect size, the number of dislocations did not. The average extent of the glenoid defect was 12.0% in rugby players, 8.9% in American football players, 4.7% in female athletes, and 4.5% in baseball players. Glenoid defects were significantly smaller in male baseball players and female athletes than in male collision athletes.Conclusion:The glenoid defect is significantly enlarged by damage due to recurrent dislocation and subluxation; therefore, glenoid rim morphology differs markedly between primary and recurrent instability. Glenoid defect size is also influenced by sex and by the type of sport.

Size dependent emission stimulation in ZnO nanosheets

Photoluminescence (PL), X ray diffraction (XRD) and Raman scattering have been studied in crystalline ZnO nanosheets (NSs) of different sizes, estimated by scanning electronic microscopy (SEM). ZnO NSs with the size from the range of 60–600nm were created by the electrochemical (anodization) method and followed thermal annealing at 400°C for 2h in ambient air. XRD study confirms the wurtzite structure of ZnO NSs and has revealed that the lattice parameters increase monotonically with decreasing NS sizes. Simultaneously the intensity of a set of Raman peaks increases and Raman peaks shift into the low energy range. The surface phonon has been detected in smallest size ZnO NSs.Two types of PL bands deal with a set of phonon replicas of free excitons and the defect related emission have been detected in ZnO NSs. The intensity enhancement of exciton- and defect-related PL bands with decreasing ZnO NS sizes has been detected. The intensity stimulation of exciton-related PL bands is attributed to the realization of the week confinement and the exciton-light coupling with the formation of polariton in small size ZnO NSs of 67–170nm. The intensity rising of defect-related PL bands is attributed to the concentration enlargement of surface defects when the surface to volume ration increases at decreasing ZnO NS sizes. Numerical simulations of radiative lifetimes and exciton radiative recombination rates in ZnO NSs for different emission wavelengths have been done using the exciton-light coupling model. Then the experimental and numerically simulated PL results have been compared and discussed.

Progression of optic neuropathy after disc hemorrhage in primary angle-closure glaucoma

We describe progressive optic neuropathy after recurrent disc hemorrhages in patients with primary angle-closure glaucoma. Three Taiwanese Chinese patients with primary angle-closure glaucoma and recurrent disc hemorrhages were followed for 10 years. Despite good control of intraocular pressure, progressive enlargement of optic disc cupping and visual field defects corresponding to the location of disc hemorrhages were noted after recurrent hemorrhages. Disc hemorrhages are not particularly rare in primary angle-closure glaucoma and may be a sign of a poor prognosis.

New transcatheter techniques for creation or enlargement of atrial septal defects in infants with complex congenital heart disease

To describe a series of 8 consecutive infants (5 with transposition of the great arteries [TGA] and 3 with hypoplastic left heart syndrome [HLHS]) who underwent nonconventional septostomy techniques. For some complex congenital heart defects, an unrestrictive atrial septal defect (ASD) is essential to achieve an adequate cardiac output and/or systemic saturation. In some scenarios, the use of conventional septostomy techniques may be technically difficult, hazardous, and/or ineffective. Use of transhepatic approach, cutting balloons, and radiofrequency perforation with stenting of the atrial septum. The size of the ASD and the oxygen saturation increased in all patients with no major complications. In those with TGA, the ASDs were considered to be of good size at the arterial switch operation. Two of the 3 patients with hybrid palliation for HLHS have developed some degree of obstruction within the interatrial stent over 2-3 months. At surgery, the stents were found to be secured within the septum with one showing significant fibrous ingrowth after uneventful removal. The other had some nonobstructive ingrowth. Creation or enlargement of ASDs in infants using new nonconventional transcatheter techniques is feasible, safe, and effective, at least in the short-to-mid-term follow-up. Infants with TGA seem to benefit the most because the procedure results in satisfactory clinical stability for subsequent early surgical intervention. In infants with HLHS palliated by a hybrid approach, stent implantation to the atrial septum seems to buy enough time to bring them to the phase II safely despite progressive in-stent obstruction.

Transcatheter creation and enlargement of ventricular septal defects for relief of ventricular hypertension

Creation or enlargement of a ventricular septal defect is indicated in rare clinical situations. In the setting of double-outlet right ventricle requiring single-ventricle palliation, left ventricular outflow tract obstruction caused by progressive restriction at the ventricular septal defect poses an uncommon but recognized dilemma. In this situation surgical ventricular septal defect enlargement may be desirable but risks damage to the atrioventricular valve or conduction system. We report the results of a novel technique for transcatheter creation or enlargement of ventricular septal defects as an alternative to reoperation when decompression of an isolated ventricle is indicated. Eight patients had undergone transcatheter ventricular septal defect enlargement or creation, and 3 of these patients had undergone 4 prior surgical attempts at left ventricular decompression. Ventricular aneurysms had developed in 3 patients before intervention. Five patients underwent ventricular septal defect creation, and 3 patients underwent enlargement of existing ventricular septal defects. Initial intervention resulted in a decreased ventricular septal defect pressure gradient from 76.9 mm Hg to 20.3 mm Hg (P = .004). There was no procedural mortality or sustained heart block. Two patients had moderate-to-severe atrioventricular valve regurgitation, and 1 required surgical repair. At last follow-up, all ventricular septal defects remained patent, with recurrent obstruction in the majority of cases caused by muscular hypertrophy beyond the stent margins. In 1 patient a ventricular aneurysm has regressed in size. Repeat intervention reduced recurrent obstruction, but recurrence was the rule. When reoperation is considered high risk, transcatheter creation and enlargement of ventricular septal defects is possible with excellent short-term results. Recurrent obstruction is common but responds to repeated intervention. Further studies are required to establish clinical benefit.

Creation and Enlargement of Atrial Defects in Congenital Heart Disease

Transcatheter creation and enlargement of interatrial defects (IAD) may improve hemodynamics; however, procedural outcomes have not been well defined. Hospital records were reviewed for children who underwent percutaneous procedures to create and enlarge an IAD and were grouped as follows: (1) right and (2) left heart obstructive lesions, (3) left atrial (LA) decompression during left heart assist, (4) failing Fontan circulation, and (5) miscellaneous. Forty-five children (mean age, 3.4 +/- 4.7 years; 30 (67%) male) were identified. In group 1 (n = 6), all achieved endpoints of right atrial (RA) decompression (n = 2), improved left ventricular filling (n = 3), or improved arterial saturations (n = 1). In group 2 (n = 18), mean LA pressure decreased (21 +/- 6 to 13 +/- 5 mmHg, p < 0.001) and arterial saturations increased (61 +/- 13% to 78 +/- 11%, p < 0.001). All except 2 patients achieved definitive repair, further palliation (n = 9), or heart transplantation (HTX) (n = 7). In group 3 (n = 5), the LA was decompressed (21 to 13 mmHg, p = 0.03) in all, and all except 1 patient survived to HTX (n = 2) or full recovery (n = 2). In group 4 (n = 11), of 7 patients with a low cardiac output syndrome after surgery, despite improved atrial shunting, 3 died and 1 required a HTX. In group 5 (n = 5), RA decompression (n = 1) or improved arterial saturation (n = 4) was achieved in all. Overall, 5-year HTX free survival was 75%. Mechanical ventilation before the procedure (p < 0.001), the need for a blade septostomy (p = 0.002), and higher LA pressures after the procedure (p = 0.04) independently predicted mortality or the requirement for HTX. Transcatheter optimization of an atrial communication can help optimize treatment strategies and has a low procedural risk.

Volume changes of the molten globule transitions of horse heart ferricytochrome c: A thermodynamic cycle

Volume changes among the unfolded (U), native (N), and molten globule (MG) conformations of horse heart ferricytochrome c have been measured. U to N (pH 2 to pH 7) was determined in the absence of added salt to be -136 +/- 5 mL/mol protein. U to MG (pH 2, no added salt to pH 2, 0.5 M KCl) yielded + 100 +/- 6 mL/mol. MG to N was broken into two steps, N to NClx at pH 7 by addition of buffered KCl to buffered protein lacking added salt (NClx = N interacting with an unknown number, X, of chloride ions), and MG to NClx by jumping MG at pH 2 in 0.5 M KCl to pH7 at the same salt concentration. The delta V of N to NClx was -30.9 +/- 1.4 mL/mol protein, whereas MG to NClx entailed a delta V of -235 +/- 6 mL/mol. Within experimental error, the results add up to zero for a complete thermodynamic cycle. We believe this to be the first volumetric cycle to have been measured for the conformational transitions of a protein. The results are discussed in terms of hydration contributions from deprotonation of the protein, other hydration effects, and the formation and/or enlargement of packing defects in the protein's tertiary structure during the steps of folding.

Acquired middle cranial fossa fistulas

To the accepted classification of three types of normal pressure, nontraumatic cerebrospinal fluid (CSF) fistulas, we would add “acquired.” This type of CSF fistula tends to occur from the middle cranial fossa because of the enlargement of “pitholes” that are normally present in its anterior medial aspect. The enlargement of these bony defects is due to normal intracranial pressure variations that, not uncommonly, create meningoceles and meningoencephaloceles. A portion of the floor of this area is aerated in up to 10% of the normal population by the lateral recess of the sphenoid sinus, the pterygoid recess. Thus, this area has the potential to act as a pathway between the middle fossa and the paranasal sinuses, allowing cerebrospinal fluid to pass into the sinuses. Isotope and computerized tomographic studies are helpful in the localization of such a CSF leak. Tomography of the base of the skull, however, is essential for the ideal definition of possible routes of fistulization. If there is any question of the presence of a middle fossa fistula, these studies can show whether the floor of this area is pneumatized and whether there are any defects in the floor. The treatment of such a fistula should include generalized reinforcement of the floor of the anterior middle fossa by a middle fossa approach. If any doubt exists as to the site of leakage (anterior or middle fossa), the minimal surgical procedure should include exploration of both areas via a frontotemporal craniotomy.

Spina bifida cystica. Results of treatment of 270 consecutive cases with criteria for selection for the future.

The disappointing results of treatment in 270 consecutive unselected cases of spina bifida admitted during a 27-month period are detailed. Massive effort has led to much avoidable suffering at an exorbitant cost in manpower and money. This study confirms the validity of those adverse prognostic criteria defined in an earlier study and which form a basis for selection. These are (1) thoracolumbar lesions, (2) severe paraplegia, (3) gross enlargement of head, (4) kyphosis, and (5) other severe congenital defects, or birth injuries. It is shown again that selection is possible on the first day of life on purely objective criteria; that it is essential for the benefit of all those affected—whether they are for treatment or no treatment; and that it is in the interest of their families and the community.

Simulated progression of visual field defects of glaucoma.

THIS PAPER emphasizes certain ocular factors which, by reducing the intensity of the retinal stimulus from a test object, may cause simulated progression of the visual field defects of glaucoma and thereby give misleading information regarding the glaucomatous state. Some pertinent clinical and experimental observations are presented. The factors investigated by us were changes in transparency of the ocular media, refractive disturbances, and miosis. All these conditions diminish the amount of light falling upon a given area of the retina from a given test object. The size of any visual field defect which might be present therefore increases correspondingly. Emphasis on the effects of these factors upon the visual field changes of chronic simple (wide-angle) glaucoma is of great importance because visual field studies offer the most reliable method of evaluating the effectiveness of medical therapy. Likewise, progressive enlargement of visual field defects serves as the best and most dependable