The nanoscale confinement is of great important for the industrial applications of molecular sieve,desalination,and also essential in bio-logical transport systems.Massive efforts have been devoted to the influence of...The nanoscale confinement is of great important for the industrial applications of molecular sieve,desalination,and also essential in bio-logical transport systems.Massive efforts have been devoted to the influence of restricted spaces on the properties of confined fluids.However,the situation of channel-wall is crucial but attracts less attention and remains unknown.To fundamentally understand the mechanism of channel-walls in nanoconfinement,we investigated the interaction between the counter-force of the liquid and interlamellar spacing of nanochannel walls by considering the effect of both spatial confinement and surface wettability.The results reveal that the nanochannel stables at only a few discrete spacing states when its confinement is within 1.4 nm.The quantized interlayer spacing is attributed to water molecules becoming laminated structures,and the stable states are corresponding to the monolayer,bilayer and trilayer water configurations,respectively.The results can potentially help to understand the characterized interlayers spacing of graphene oxide membrane in water.Our findings are hold great promise in design of ion filtration membrane and artificial water/ion channels.展开更多
AIM:To investigate tomographic features of late corneal ectasia after keratoplasty for keratoconus and compare penetrating keratoplasty(PK)and deep anterior lamellar keratoplasty(DALK)in terms of incidence,time of ons...AIM:To investigate tomographic features of late corneal ectasia after keratoplasty for keratoconus and compare penetrating keratoplasty(PK)and deep anterior lamellar keratoplasty(DALK)in terms of incidence,time of onset and risk factors of corneal ectasia.METHODS:Sixty eyes with PK and 30 eyes with DALK operated between 1999 and 2021 were analyzed.Final Pentacam scans were evaluated together with vision and previous topographies.Main outcome measures were vision,K values,apparent thinning on graft-host cornea and the difference between opposing quadrants in the thinnest point measurements.Anterior segment optic coherence tomography was performed for further evaluation.RESULTS:Mean follow-up was 127.2mo(24–282mo)in PK,and 64.3mo(24–144mo)in DALK.K max was higher in DALK(60.6 vs 56.7 D,P=0.012).Inferior recipient was thinner(595.9μm)in PK than DALK(662.2μm,P=0.021),due to longer follow-up.Overall corneal ectasia rate was 20.0% within 24y.Ectasia rate was the same(6.7%)in DALK 2/30 and in PK 4/60 in 10y and 13.3%in 12y(4/30 and 8/60,respectively).It increased to 23.3%(14/60)in PK over 24y.While ectasia was not seen before 7y in PK,it could be seen in DALK starting from the 5^(th) year.The intervals between keratoplasty and ectasia were 144.5mo in PK and 99mo in DALK.Inferior recipient was significantly thinner in 18 eyes with ectasia(502.7μm)compared to 76 non-ectasia(649.1μm,P=0.000).Inferior graft was thinner(561.0 vs 620.4μm,P=0.006),K max(63.3 vs 56.5 D,P=0.000),and anterior elevation was higher in ectasia(89.1 vs 48.6μm,P=0.002).Accelerated crosslinking was performed on 5 eyes.CONCLUSION:Inferior-superior recipient and inferior graft thinning on tomography,with high K max and anterior elevation emerge as the most reliable criteria for the diagnosis of late ectasia.The incidence of corneal ectasia increases with the time.展开更多
AIM:To investigate whether the two-step strategy[conjunctival flap covering surgery(CFCS)combined with secondary deep anterior lamellar keratoplasty(DALK)]is effective for patients with high-risk fungal keratitis(FK)....AIM:To investigate whether the two-step strategy[conjunctival flap covering surgery(CFCS)combined with secondary deep anterior lamellar keratoplasty(DALK)]is effective for patients with high-risk fungal keratitis(FK).METHODS:In this noncomparative,retrospective case series,10 subjects(6 males,4 females)with a mean age of 56.5±7.1(range 47-72)y with high-risk FK undergone the two-step strategy were included.Reported outcome measures were healing of the corneal ulcer,recurrence of FK,reject reaction,improvement in best corrected visual acuity(BCVA)and relevant complications.RESULTS:The average diameter of corneal infiltrates was 7.50±0.39 mm,ranging from 6.94 to 8.13 mm.The mean depth of corneal infiltrates was 422.4±77.1μm,ranging from 350 to 535μm.The mean corneal thickness was 597.4±117.3μm,ranging from 458 to 851μm.Hypopyon and endothelial plaques were presented in all patients.The period between the two steps was 3.65±0.9(ranging from 3 to 5)mo.The graft diameter was 7.75±0.39 mm.At the last follow-up(average 9.25±3.39,ranging from 5.5 to 17mo),no fungal recurrence or graft rejection appeared,and all patients showed improvement of BCVA.One patient suffered from liver function impairment due to oral voriconazole for 4wk and recovered spontaneously after 1wk of drug withdrawal.CONCLUSION:The two-step strategy is safe and effective in the treatment of high-risk FK by transforming intentional therapeutic penetrating keratoplasty during acute infection to later optical DALK.It is a practical strategy,especially in areas lacking fresh donor corneas and eye bank services.展开更多
Background: Respiratory distress syndrome (RDS) is a major cause of neonatal morbidity and mortality, affecting approximately 1% of all live births and 10% of all preterm infants. Lamellar bodies represent a storage f...Background: Respiratory distress syndrome (RDS) is a major cause of neonatal morbidity and mortality, affecting approximately 1% of all live births and 10% of all preterm infants. Lamellar bodies represent a storage form of pulmonary surfactant within Type II pneumocytes, secretion of which increases with advancing gestational age, thus enabling prediction of the degree of FLM. Preterm premature rupture of membranes (PPROM) complicates approximately 1/3 of all preterm births. Birth within 1 week is the most likely outcome for any patient with PPROM in the absence of adjunctive treatments. Respiratory distress has been reported to be the most common complication of preterm birth. Sepsis, intraventricular haemorrhage, and necrotizing enterocolitis also are associated with prematurity, but these are less common near to term. Objective: To assess the efficacy of the amniotic fluid lamellar body counting from a vaginal pool in predicting fetal lung maturity in women with preterm premature rupture of membranes. Methods: This study was conducted at Ain Shams University Maternity Hospital in the emergency ward from January 2019 to September 2019. It included 106 women with singleton pregnancies, gestational age from 28 - 36 weeks with preterm premature rupture of membranes. This study is designed to assess the efficacy of the amniotic fluid lamellar body counting (LBC) from a vaginal pool in predicting fetal lung maturity in women with preterm premature rupture of membranes. Results: The current study revealed a highly significant increase in the lamellar body count in cases giving birth to neonates without RDS compared to that cases giving birth to neonates with RDS. Also, no statistically significant difference between LBC and age, parity and number of previous miscarriages in the mother was found. Gestational age at delivery was significantly lower among cases with respiratory distress. Steroid administration was significantly less frequent among cases with respiratory distress. However, lamellar bodies had high diagnostic performance in the prediction of respiratory distress. Conclusion: Lamellar body count (LBC) is an effective, safe, easy, and cost-effective method to assess fetal lung maturity (FLM). It does not need a highly equipped laboratory or specially trained personnel, it just needs the conventional blood count analyzer. Measurement of LBC is now replacing the conventional Lecithin/Sphyngomyelin L/S ratio. LBC cut-off value of ≤42.5 × 10<sup>3</sup>/μL can be used safely to decide fetal lung maturity with sensitivity of 95.7% and specificity of 97.6%.展开更多
In order to provide ultraviolet barrier, antifungal and antibacterial properties, nano-zinc oxide (ZnO) was added to lamellar zirconium phosphate (ZrP). The phosphate was synthesized via reaction of zirconium oxychlor...In order to provide ultraviolet barrier, antifungal and antibacterial properties, nano-zinc oxide (ZnO) was added to lamellar zirconium phosphate (ZrP). The phosphate was synthesized via reaction of zirconium oxychloride octahydrate and phosphoric acid following its chemical modification with Jeffamine and nano-ZnO. Diffractometric, morphological, thermal, structural and relaxometric evaluations were conducted. Fourier transform infrared spectroscopy (FTIR) revealed increase of the area between 4000 - 3000 cm<sup>-1</sup> due to the formation of ionic specie PO? <sup>+</sup>NH<sub>3</sub>-[C-(H)(CH<sub>3</sub>)-CH<sub>2</sub>-O-(C-(H)(CH<sub>3</sub>)-CH<sub>2</sub>-O)<sub>8</sub>-(CH<sub>2</sub>-CH<sub>2</sub>-O-CH<sub>3</sub>)] and nano-ZnO particles. Wide-angle X-ray diffraction indicated that intercalation of Jeffamine was successful. Thermogravimetry confirmed that nano-ZnO particle forced the expulsion of Jeffamine outside ZrP galleries. Scanning electron microscopy evidenced the Jeffamine intercalation and sample heterogeneity. Hydrogen molecular relaxation indicated the increase of molecular rigidity owing to the formation of ionic specie and the addition of nano-ZnO particles. It was postulated that a multifunctional and miscellaneous material constituted by as prepared ZrP, some delaminated ZrP platelets and nano-ZnO particles was achieved. The material has potential for usage as filler in polymeric composites.展开更多
Deep anterior lamellar keratoplasty(DALK) has recently been introduced as an alternative procedure to penetrating keratoplasty(PK) for corneal pathologies not affecting the corneal endothelium. DALK does not rely on d...Deep anterior lamellar keratoplasty(DALK) has recently been introduced as an alternative procedure to penetrating keratoplasty(PK) for corneal pathologies not affecting the corneal endothelium. DALK does not rely on donor endothelium and requires less rigid criteria for donor corneal tissue quality. Therefore, DALK makes it possible to use donor corneas deemed unsuitable for PK. Furthermore, lamellar keratoplasty allows acellular corneal tissue to be transplanted. As a result, long-term preservation techniques are being revisited to increase the availability of donor corneas and subsequently alleviate constraints of availability, cost, storage, and transportation in many countries. The recent alterations in corneal transplantation techniques and hence the type of donor cornea tissues used for each technique, may require corneal surgeons and eye banks to reevaluate their selection criteria. The purpose of this systematic review is to present an updated analysis on the type and quality of donor corneas used for PK and DALK, assess the influence of donor and eye bank factors on the quality of donor corneas, and determine whether any of these donor factors affect clinical outcomes, complications, and graft survivals.展开更多
Abstract： The dynamic spheroidization kinetics behavior of Ti-6.5Al-2Zr-1Mo-1V alloy with a lamellar initial microstructure was studied by isothermal hot compression tests in the temperature range of 750-950℃ and st...Abstract： The dynamic spheroidization kinetics behavior of Ti-6.5Al-2Zr-1Mo-1V alloy with a lamellar initial microstructure was studied by isothermal hot compression tests in the temperature range of 750-950℃ and strain rates of 0.001-10 s^-1. The results show that the spheroidized fraction of alpha lamellae increases with the increase of temperature and the decrease of strain rate. The spheroidization kinetics curves predicted by JMAK equation agree well with experimental ones. The corresponding SEM and TEM observations indicate that the dynamic spheroidization process can be divided into two stages. The primary stage is boundary splitting formed by two competing mechanisms which are dynamic recrystallization and mechanical twin. In the second stage, the penetration of beta phase into the alpha/alpha grain boundaries is dominant, which is controlled in nature by diffusion of the chemical elements such as Al, Mo and V.展开更多
The high temperature deformation behaviors of α＋β type titanium alloy TC11 （Ti-6.5Al-3.5Mo-1.5Zr-0.3Si） with coarse lamellar starting microstructure were investigated based on the hot compression tests in the tem...The high temperature deformation behaviors of α＋β type titanium alloy TC11 （Ti-6.5Al-3.5Mo-1.5Zr-0.3Si） with coarse lamellar starting microstructure were investigated based on the hot compression tests in the temperature range of 950-1100 ℃ and the strain rate range of 0.001-10 s-1. The processing maps at different strains were then constructed based on the dynamic materials model, and the hot compression process parameters and deformation mechanism were optimized and analyzed, respectively. The results show that the processing maps exhibit two domains with a high efficiency of power dissipation and a flow instability domain with a less efficiency of power dissipation. The types of domains were characterized by convergence and divergence of the efficiency of power dissipation, respectively. The convergent domain in a＋fl phase field is at the temperature of 950-990 ℃ and the strain rate of 0.001-0.01 s^-1, which correspond to a better hot compression process window of α＋β phase field. The peak of efficiency of power dissipation in α＋β phase field is at 950 ℃ and 0.001 s 1, which correspond to the best hot compression process parameters of α＋β phase field. The convergent domain in β phase field is at the temperature of 1020-1080 ℃ and the strain rate of 0.001-0.1 s^-l, which correspond to a better hot compression process window of β phase field. The peak of efficiency of power dissipation in ℃ phase field occurs at 1050 ℃ over the strain rates from 0.001 s^-1 to 0.01 s^-1, which correspond to the best hot compression process parameters of ,8 phase field. The divergence domain occurs at the strain rates above 0.5 s^-1 and in all the tested temperature range, which correspond to flow instability that is manifested as flow localization and indicated by the flow softening phenomenon in stress-- strain curves. The deformation mechanisms of the optimized hot compression process windows in a＋β and β phase fields are identified to be spheroidizing and dynamic recrystallizing controlled by self-diffusion mechanism, respectively. The microstructure observation of the deformed specimens in different domains matches very well with the optimized results.展开更多
The Ti-47Al-2Nb-2Cr-0.2W alloy sheets were obtained by hot pack rolling. The as-rolled sheet has an inhomogeneous duplex microstructure composed of elongated gamma grains and lamellar colonies. Heat treatments were co...The Ti-47Al-2Nb-2Cr-0.2W alloy sheets were obtained by hot pack rolling. The as-rolled sheet has an inhomogeneous duplex microstructure composed of elongated gamma grains and lamellar colonies. Heat treatments were conducted on the as-rolled sheets. The results show that the microstructures with different sizes and grain boundary morphologies were developed after different heat treatments. A coarse fully lamellar structure can be refined if the heating time, together with the cooling rate, is appropriately controlled. The grain growth exponent is found to be approximately 0.2, and the activation energy of grain boundary migration of the alloy is around 225 kJ/mol.展开更多
TC11 titanium alloy samples with lamellar microstructrue were compressed on a Gleeble 1500D Simulator.Compression tests were carried out at 950 ℃ and a strain rate of 0.1 s-1 with height reduction of 20%,40% and 60%,...TC11 titanium alloy samples with lamellar microstructrue were compressed on a Gleeble 1500D Simulator.Compression tests were carried out at 950 ℃ and a strain rate of 0.1 s-1 with height reduction of 20%,40% and 60%,respectively.Microstruture of the compressed TC11 alloy was obeserved and analyzed by optical microscopy(OM),transmission electron microscope(TEM),electron back-scattered diffraction(EBSD).The lamellar disintegration mechanism of the TC11 titanium alloy was deduced.The results indicated that the compressive deformation promoted the phase transformation in bi-phase area.βphase layers were formed along the gliding planes inα phase,and α slivers were disintegrated into many small flakes through theα/βinterface slipping.展开更多
TiAl-based alloys are potentially used as high-temperature structural materials with a high specific strength in the range of^900°C.However,the mechanical properties of TiAl-based alloys are extremely anisotropic...TiAl-based alloys are potentially used as high-temperature structural materials with a high specific strength in the range of^900°C.However,the mechanical properties of TiAl-based alloys are extremely anisotropic with respect to the lamellar orientation of the microstructures.A balance combination of room-temperature ductility and strength can be achieved when the lamellar orientation are aligned parallel to the tensile stress direction.Lamellar orientation control of TiAl-based alloys by directional solidification technique has been widely studied in recent years.Two different directional solidification processes can be used to modify the lamellar orientation.One is a seeding technique and the other is adjusting the solidification path.This paper reviews the principles of the two methods and their progress.The influence of alloy composition and solidification parameters on lamellar orientation control is also discussed.展开更多
The independent influence of microstructural features on fracture toughness of TC21alloy with lamellar microstructure was investigated.Triple heat treatments were designed to obtain lamellar microstructures with diffe...The independent influence of microstructural features on fracture toughness of TC21alloy with lamellar microstructure was investigated.Triple heat treatments were designed to obtain lamellar microstructures with different parameters,which were characterized by OM and SEM.The size and content ofαplates were mainly determined by cooling rate from singleβphase field and solution temperature in two-phase field;while the precipitation behavior of secondaryαplatelets was dominantly controlled by aging temperature in two-phase field.The content and thickness ofαplates and the thickness of secondaryαplatelets were important microstructural features influencing the fracture toughness.Both increasing the content ofαplates and thickeningαplates(or secondaryαplatelets)could enhance the fracture toughness of TC21alloy.Based on energy consumption by the plastic zone of crack tip inαplates,a toughening mechanism for titanium alloys was proposed.展开更多
AIM：To evaluate the functional and aesthetic outcomes of upper eyelid cicatricial entropion（UCE） correction using anterior lamellar recession（ALR） with addressing the associated conditions including dermatochalas...AIM：To evaluate the functional and aesthetic outcomes of upper eyelid cicatricial entropion（UCE） correction using anterior lamellar recession（ALR） with addressing the associated conditions including dermatochalasis,brow ptosis,blepharoptosis,and lid retraction.METHODS：Chart review of patients with upper lid cicatricial entropion who had undergone ALR from 2013 to 2016 was reviewed.Success was defi ned as the lack of any lash in contact with the globe,no need for a second procedure,and acceptable cosmesis at the fi nal follow up.RESULTS：Sixty eight patients（97 eyelids） were operated by ALR with simultaneous correction of associated lid problems in each case when necessary.The mean followup time was 17.8 mo（range,6.0-24.0 mo）.Concomitantly,levator tucking was performed in 19 eyelids（19.6%）,upper lid retractor recession in 18 eyelids（18.6%）,and internal browpexy in 31 eyelids（32.0%）.In 95.8% of patients（95%CI：0.85-0.96）,satisfactory functional and cosmetic outcome was achieved with a single surgical procedure.CONCLUSION：Based on the principles of lamellar recession and concurrently addressing the associated lid problems,this approach is an effective and safe treatment of UCE.展开更多
·AIM: To describe the initial outcomes and safety of femtosecond laser-assisted deep anterior lamellar keratoplasty(DALK) for keratoconus and post-LASIK keratectasia.·METHODS: In this non-comparative case se...·AIM: To describe the initial outcomes and safety of femtosecond laser-assisted deep anterior lamellar keratoplasty(DALK) for keratoconus and post-LASIK keratectasia.·METHODS: In this non-comparative case series, 10 eyes of 9 patients underwent DALK procedures with a femtosecond laser(Carl Zeiss Meditec AG, Jena,Germany). Of the 9 patients, 7 had keratoconus and 2had post-LASIK keratectasia. A 500 kHz VisuMax femtosecond laser was used to perform corneal cuts on both donor and recipient corneas. The outcome measures were the uncorrected visual acuity(UCVA),best-corrected visual acuity(BCVA), corneal thickness,astigmatism, endothelial density count(EDC), and corneal power.·RESULTS: All eyes were successfully treated. Early postoperative evaluation showed a clear graft in all cases. Intraoperative complications included one case of a small Descemet’s membrane perforation.Postoperatively, there was one case of stromal rejection,one of loosened sutures, and one of wound dehiscence.A normal corneal pattern topography and transparency were restored, UCVA and BCVA improved significantly,and astigmatism improved slightly. There was no statistically significant decrease in EDC.· CONCLUSION: Our early results indicate that femtosecond laser-assisted deep anterior lamellar keratoplasty could improve UCVA and BCVA in patients with anterior corneal pathology. This approach shows promise as a safe and effective surgical choice in the treatment of keratoconus and post-LASIK keratectasia.展开更多
In the present study, the influence of natural convection on the lamellar eutectic growth is determined by a phase-field-lattice Boltzmann study for Al-Cu eutectic alloy. The mass difference resulting from concentrati...In the present study, the influence of natural convection on the lamellar eutectic growth is determined by a phase-field-lattice Boltzmann study for Al-Cu eutectic alloy. The mass difference resulting from concentration difference led to the fluid flow, and a robust parallel and adaptive mesh refinement algorithm was employed to improve the computational efficiency without any compromising accuracy. Results show that the existence of natural convection would affect the growth undercooling and thus control the interface shape by adjusting the lamellar width. In particular, by alternating the magnitude of the solute expansion coefficient, the strength of the natural convection is changed. Corresponding microstructure patterns are discussed and compared with those under no-convection conditions.展开更多
The fracture behavior of fully lamellar γ-TiAl alloys depends on the angle between the lamellar orientation and loading axis,but the role of the presentation of grain boundary cannot be ignored.To investigate the inf...The fracture behavior of fully lamellar γ-TiAl alloys depends on the angle between the lamellar orientation and loading axis,but the role of the presentation of grain boundary cannot be ignored.To investigate the influence of the grain boundary on the initiation and propagation of cracks,the tensile test of the alloy was conducted at room temperature with loading axis parallel and perpendicular to the lamellar orientation,respectively.The cracks adjacent to the fracture zone of the tensile specimens have been investigated to analyze the fracture behavior.Results show that the grain boundary has dual influences on the fracture behavior.When the loading axis is parallel to the lamellar orientation,cracks are preferentially initiated at and propagate along the grain boundaries.When the loading axis is perpendicular to the lamellar orientation,the grain boundaries can prevent the propagation of cracks from running across.Additionally,serrated-shape grain boundaries have a better inhibiting effect on the propagation of cracks than planar boundaries.展开更多
The microstructural stability of lamellar TiAl base alloys at high temperatures was studied by conventional and high resolution transmission electron microscopy. The influence of substructures on the thermal stability...The microstructural stability of lamellar TiAl base alloys at high temperatures was studied by conventional and high resolution transmission electron microscopy. The influence of substructures on the thermal stability of lamellar structure was emphasized. These substructures produced by thermal mechanical treatments include the interfacial dislocations and ledges, the subgrain boundaries, the impinged T(Q) twins and misorientated lamellar interfaces. The microstructural change of three kinds of lamellar TiAl base alloys containing differents type and densities of substructures were compared during exposure at 800~1 000 ℃. It was found that the existence of such substructures could accelerate the degeneration of lamellar structure, leading to the rapid necking and break up of α 2 plates, the coarsening of γ plates, and the formation of new γ grains. As a result, the lamellar structure with substructures started to degenerate after thermal exposure at 800℃ for 4.5 h. While only slight coarsening was observed at the colony boundaries in the lamellar structure without substructures even after exposure at 900 ℃ for 7 d.展开更多
The fracture behavior of fully lamellar binary γ-TiAI alloys is extremely anisotropic with respect to the lamellar orientation. For the fully lamellar Ti-46Al-0.5W-0.5Si alloy, the existence of silicide clusters play...The fracture behavior of fully lamellar binary γ-TiAI alloys is extremely anisotropic with respect to the lamellar orientation. For the fully lamellar Ti-46Al-0.5W-0.5Si alloy, the existence of silicide clusters plays a critical role on the fracture behavior. In the present study, tensile test and three point bending test were performed at room temperature with the loading axis parallel and perpendicular to the lamellar orientation, respectively. To investigate the influence of silicide clusters on the initiation and propagation of cracks, the fracture surface and the cracks adjacent to the fracture zone of the specimens have been analyzed. Results show that the fracture process is related to the morphology and distribution of the silicide clusters. Crack preferentially initiates at and propagates along the interface of silicide and a2/7 lamellar with the loading axis perpendicular to the length direction of silicide. While the silicide can prevent the propagation of cracks from running across with the crack growth direction perpendicular to the length direction of silicide.展开更多
Creep experiments have been conducted on five powder metallurgy TiAl alloys with fine grains (65～80 μm), fine lamellar spacings (0.1～0.16 μm), and different compositions [Ti 47Al(+Cr, Nb, Ta, W, Si)] at temperatur...Creep experiments have been conducted on five powder metallurgy TiAl alloys with fine grains (65～80 μm), fine lamellar spacings (0.1～0.16 μm), and different compositions [Ti 47Al(+Cr, Nb, Ta, W, Si)] at temperatures of 760 ℃ and 815 ℃ and stresses from 35 to 723 MPa. Results show that at a given lamellar spacing 1% Nb(mole fraction) with 1% Ta and replacing 0.2% Ta with 0.2% W induced little effect, but addition of 0.3% Si decreased the creep resistance by a factor of 3～4 under otherwise identical conditions. These different effects of different alloying elements are interpreted in terms of the interaction of alloy segregants with misfit and/or misorientaion dislocations at the lamellar interface. That is, the interaction retards or facilitates the climb of interfacial dislocations, which is rate controlling during creep, depending on the size of the segregants relative to the host atoms.展开更多
AIM: To compare long-term postoperative outcomes of manual and femtosecond assisted corneal trephination in deep anterior lamellar keratoplasty(FS-DALK) for keratoconus.METHODS: In the retrospective study, 17 consecut...AIM: To compare long-term postoperative outcomes of manual and femtosecond assisted corneal trephination in deep anterior lamellar keratoplasty(FS-DALK) for keratoconus.METHODS: In the retrospective study, 17 consecutive eyes that underwent vertical side cut incision FS-DALK and 22 eyes that underwent trephine incision DALK were collected over a 2-year period. Main measurements included postoperative uncorrected-visual acuity(UCVA), corrected distance visual acuity(CDVA), refractive sphere and cylinder, manifest refraction spherical equivalent(MRSE), flat and steep corneal keratometry(K1 and K2), endothelial cell density(ECD), and time of epithelium healing and suture removal.RESULTS: Groups were comparable for diagnosis and preoperative visual acuity. Follow-up averaged 23 mo(range, 12-36 mo). At 12 mo, the mean UCVA was better in the manual-DALK group(P=0.039), and the refractive sphere was lower in the FS-DALK group(P=0.040). MRSE between groups differed at 1, 6, and 12 mo postoperatively(P=0.047, 0.025, 0.042, respectively). Mean CDVA, cylinder, K1, K2,corneal astigmatism, ECD, and time of epithelium healing were similar between groups. Stability of MRSE, ECD, and K1 returned sooner after FS-DALK. Initial loosened suture removal time was earlier in the manual-DALK group(P=0.042) while complete suture removal time was similar(P=0.122).CONCLUSION: Manual and femtosecond assisted corneal trephination in DALK are options for advanced keratoconus. FS-DALK do not result in improved visual acuity but it is more stable during the follow-up period. FSDALK in the present form show limited benefit, so surgical design and parameters still need to be optimized and explored.展开更多
基金support from the National Natural Science Foundation of China(Grant Nos.12372327,12372109,11972171)National Key R&D Program of China(Grant No.2023YFB4605101).
文摘The nanoscale confinement is of great important for the industrial applications of molecular sieve,desalination,and also essential in bio-logical transport systems.Massive efforts have been devoted to the influence of restricted spaces on the properties of confined fluids.However,the situation of channel-wall is crucial but attracts less attention and remains unknown.To fundamentally understand the mechanism of channel-walls in nanoconfinement,we investigated the interaction between the counter-force of the liquid and interlamellar spacing of nanochannel walls by considering the effect of both spatial confinement and surface wettability.The results reveal that the nanochannel stables at only a few discrete spacing states when its confinement is within 1.4 nm.The quantized interlayer spacing is attributed to water molecules becoming laminated structures,and the stable states are corresponding to the monolayer,bilayer and trilayer water configurations,respectively.The results can potentially help to understand the characterized interlayers spacing of graphene oxide membrane in water.Our findings are hold great promise in design of ion filtration membrane and artificial water/ion channels.
文摘AIM:To investigate tomographic features of late corneal ectasia after keratoplasty for keratoconus and compare penetrating keratoplasty(PK)and deep anterior lamellar keratoplasty(DALK)in terms of incidence,time of onset and risk factors of corneal ectasia.METHODS:Sixty eyes with PK and 30 eyes with DALK operated between 1999 and 2021 were analyzed.Final Pentacam scans were evaluated together with vision and previous topographies.Main outcome measures were vision,K values,apparent thinning on graft-host cornea and the difference between opposing quadrants in the thinnest point measurements.Anterior segment optic coherence tomography was performed for further evaluation.RESULTS:Mean follow-up was 127.2mo(24–282mo)in PK,and 64.3mo(24–144mo)in DALK.K max was higher in DALK(60.6 vs 56.7 D,P=0.012).Inferior recipient was thinner(595.9μm)in PK than DALK(662.2μm,P=0.021),due to longer follow-up.Overall corneal ectasia rate was 20.0% within 24y.Ectasia rate was the same(6.7%)in DALK 2/30 and in PK 4/60 in 10y and 13.3%in 12y(4/30 and 8/60,respectively).It increased to 23.3%(14/60)in PK over 24y.While ectasia was not seen before 7y in PK,it could be seen in DALK starting from the 5^(th) year.The intervals between keratoplasty and ectasia were 144.5mo in PK and 99mo in DALK.Inferior recipient was significantly thinner in 18 eyes with ectasia(502.7μm)compared to 76 non-ectasia(649.1μm,P=0.000).Inferior graft was thinner(561.0 vs 620.4μm,P=0.006),K max(63.3 vs 56.5 D,P=0.000),and anterior elevation was higher in ectasia(89.1 vs 48.6μm,P=0.002).Accelerated crosslinking was performed on 5 eyes.CONCLUSION:Inferior-superior recipient and inferior graft thinning on tomography,with high K max and anterior elevation emerge as the most reliable criteria for the diagnosis of late ectasia.The incidence of corneal ectasia increases with the time.
基金Supported by the National Natural Science Foundation of China(No.82171025No.82070934)+2 种基金the Fundamental Research Funds for the Central Universities(No.HUST:2019kfy XMBZ065)the Key Research and Development Program of Hubei Province(No.2021BCA146)the Clinical Research Foundation of Wuhan Union Hospital(No.2021xhlcyj03)。
文摘AIM:To investigate whether the two-step strategy[conjunctival flap covering surgery(CFCS)combined with secondary deep anterior lamellar keratoplasty(DALK)]is effective for patients with high-risk fungal keratitis(FK).METHODS:In this noncomparative,retrospective case series,10 subjects(6 males,4 females)with a mean age of 56.5±7.1(range 47-72)y with high-risk FK undergone the two-step strategy were included.Reported outcome measures were healing of the corneal ulcer,recurrence of FK,reject reaction,improvement in best corrected visual acuity(BCVA)and relevant complications.RESULTS:The average diameter of corneal infiltrates was 7.50±0.39 mm,ranging from 6.94 to 8.13 mm.The mean depth of corneal infiltrates was 422.4±77.1μm,ranging from 350 to 535μm.The mean corneal thickness was 597.4±117.3μm,ranging from 458 to 851μm.Hypopyon and endothelial plaques were presented in all patients.The period between the two steps was 3.65±0.9(ranging from 3 to 5)mo.The graft diameter was 7.75±0.39 mm.At the last follow-up(average 9.25±3.39,ranging from 5.5 to 17mo),no fungal recurrence or graft rejection appeared,and all patients showed improvement of BCVA.One patient suffered from liver function impairment due to oral voriconazole for 4wk and recovered spontaneously after 1wk of drug withdrawal.CONCLUSION:The two-step strategy is safe and effective in the treatment of high-risk FK by transforming intentional therapeutic penetrating keratoplasty during acute infection to later optical DALK.It is a practical strategy,especially in areas lacking fresh donor corneas and eye bank services.
文摘Background: Respiratory distress syndrome (RDS) is a major cause of neonatal morbidity and mortality, affecting approximately 1% of all live births and 10% of all preterm infants. Lamellar bodies represent a storage form of pulmonary surfactant within Type II pneumocytes, secretion of which increases with advancing gestational age, thus enabling prediction of the degree of FLM. Preterm premature rupture of membranes (PPROM) complicates approximately 1/3 of all preterm births. Birth within 1 week is the most likely outcome for any patient with PPROM in the absence of adjunctive treatments. Respiratory distress has been reported to be the most common complication of preterm birth. Sepsis, intraventricular haemorrhage, and necrotizing enterocolitis also are associated with prematurity, but these are less common near to term. Objective: To assess the efficacy of the amniotic fluid lamellar body counting from a vaginal pool in predicting fetal lung maturity in women with preterm premature rupture of membranes. Methods: This study was conducted at Ain Shams University Maternity Hospital in the emergency ward from January 2019 to September 2019. It included 106 women with singleton pregnancies, gestational age from 28 - 36 weeks with preterm premature rupture of membranes. This study is designed to assess the efficacy of the amniotic fluid lamellar body counting (LBC) from a vaginal pool in predicting fetal lung maturity in women with preterm premature rupture of membranes. Results: The current study revealed a highly significant increase in the lamellar body count in cases giving birth to neonates without RDS compared to that cases giving birth to neonates with RDS. Also, no statistically significant difference between LBC and age, parity and number of previous miscarriages in the mother was found. Gestational age at delivery was significantly lower among cases with respiratory distress. Steroid administration was significantly less frequent among cases with respiratory distress. However, lamellar bodies had high diagnostic performance in the prediction of respiratory distress. Conclusion: Lamellar body count (LBC) is an effective, safe, easy, and cost-effective method to assess fetal lung maturity (FLM). It does not need a highly equipped laboratory or specially trained personnel, it just needs the conventional blood count analyzer. Measurement of LBC is now replacing the conventional Lecithin/Sphyngomyelin L/S ratio. LBC cut-off value of ≤42.5 × 10<sup>3</sup>/μL can be used safely to decide fetal lung maturity with sensitivity of 95.7% and specificity of 97.6%.
文摘In order to provide ultraviolet barrier, antifungal and antibacterial properties, nano-zinc oxide (ZnO) was added to lamellar zirconium phosphate (ZrP). The phosphate was synthesized via reaction of zirconium oxychloride octahydrate and phosphoric acid following its chemical modification with Jeffamine and nano-ZnO. Diffractometric, morphological, thermal, structural and relaxometric evaluations were conducted. Fourier transform infrared spectroscopy (FTIR) revealed increase of the area between 4000 - 3000 cm<sup>-1</sup> due to the formation of ionic specie PO? <sup>+</sup>NH<sub>3</sub>-[C-(H)(CH<sub>3</sub>)-CH<sub>2</sub>-O-(C-(H)(CH<sub>3</sub>)-CH<sub>2</sub>-O)<sub>8</sub>-(CH<sub>2</sub>-CH<sub>2</sub>-O-CH<sub>3</sub>)] and nano-ZnO particles. Wide-angle X-ray diffraction indicated that intercalation of Jeffamine was successful. Thermogravimetry confirmed that nano-ZnO particle forced the expulsion of Jeffamine outside ZrP galleries. Scanning electron microscopy evidenced the Jeffamine intercalation and sample heterogeneity. Hydrogen molecular relaxation indicated the increase of molecular rigidity owing to the formation of ionic specie and the addition of nano-ZnO particles. It was postulated that a multifunctional and miscellaneous material constituted by as prepared ZrP, some delaminated ZrP platelets and nano-ZnO particles was achieved. The material has potential for usage as filler in polymeric composites.
基金Supported by The Ophthalmic Research Center,Shahid Beheshti University of Medical Sciences,Tehran,Iran
文摘Deep anterior lamellar keratoplasty(DALK) has recently been introduced as an alternative procedure to penetrating keratoplasty(PK) for corneal pathologies not affecting the corneal endothelium. DALK does not rely on donor endothelium and requires less rigid criteria for donor corneal tissue quality. Therefore, DALK makes it possible to use donor corneas deemed unsuitable for PK. Furthermore, lamellar keratoplasty allows acellular corneal tissue to be transplanted. As a result, long-term preservation techniques are being revisited to increase the availability of donor corneas and subsequently alleviate constraints of availability, cost, storage, and transportation in many countries. The recent alterations in corneal transplantation techniques and hence the type of donor cornea tissues used for each technique, may require corneal surgeons and eye banks to reevaluate their selection criteria. The purpose of this systematic review is to present an updated analysis on the type and quality of donor corneas used for PK and DALK, assess the influence of donor and eye bank factors on the quality of donor corneas, and determine whether any of these donor factors affect clinical outcomes, complications, and graft survivals.
基金Project(2014ZE56015)supported by Aeronautical Science Foundation of ChinaProject(51261020)supported by the National Natural Science Foundation of ChinaProject(Zk201001004)supported by the Open Fund of the Aeronautical Science and Technology Key Laboratory of Aeronautical Material Hot Processing Technology,China
文摘Abstract： The dynamic spheroidization kinetics behavior of Ti-6.5Al-2Zr-1Mo-1V alloy with a lamellar initial microstructure was studied by isothermal hot compression tests in the temperature range of 750-950℃ and strain rates of 0.001-10 s^-1. The results show that the spheroidized fraction of alpha lamellae increases with the increase of temperature and the decrease of strain rate. The spheroidization kinetics curves predicted by JMAK equation agree well with experimental ones. The corresponding SEM and TEM observations indicate that the dynamic spheroidization process can be divided into two stages. The primary stage is boundary splitting formed by two competing mechanisms which are dynamic recrystallization and mechanical twin. In the second stage, the penetration of beta phase into the alpha/alpha grain boundaries is dominant, which is controlled in nature by diffusion of the chemical elements such as Al, Mo and V.
基金Project (51005112) supported by the National Natural Science Foundation of ChinaProject (2010ZF56019) supported by the Aviation Science Foundation of China+1 种基金Project (GJJ11156) supported by the Education Commission of Jiangxi Province, ChinaProject(GF200901008) supported by the Open Fund of National Defense Key Disciplines Laboratory of Light Alloy Processing Science and Technology, China
文摘The high temperature deformation behaviors of α＋β type titanium alloy TC11 （Ti-6.5Al-3.5Mo-1.5Zr-0.3Si） with coarse lamellar starting microstructure were investigated based on the hot compression tests in the temperature range of 950-1100 ℃ and the strain rate range of 0.001-10 s-1. The processing maps at different strains were then constructed based on the dynamic materials model, and the hot compression process parameters and deformation mechanism were optimized and analyzed, respectively. The results show that the processing maps exhibit two domains with a high efficiency of power dissipation and a flow instability domain with a less efficiency of power dissipation. The types of domains were characterized by convergence and divergence of the efficiency of power dissipation, respectively. The convergent domain in a＋fl phase field is at the temperature of 950-990 ℃ and the strain rate of 0.001-0.01 s^-1, which correspond to a better hot compression process window of α＋β phase field. The peak of efficiency of power dissipation in α＋β phase field is at 950 ℃ and 0.001 s 1, which correspond to the best hot compression process parameters of α＋β phase field. The convergent domain in β phase field is at the temperature of 1020-1080 ℃ and the strain rate of 0.001-0.1 s^-l, which correspond to a better hot compression process window of β phase field. The peak of efficiency of power dissipation in ℃ phase field occurs at 1050 ℃ over the strain rates from 0.001 s^-1 to 0.01 s^-1, which correspond to the best hot compression process parameters of ,8 phase field. The divergence domain occurs at the strain rates above 0.5 s^-1 and in all the tested temperature range, which correspond to flow instability that is manifested as flow localization and indicated by the flow softening phenomenon in stress-- strain curves. The deformation mechanisms of the optimized hot compression process windows in a＋β and β phase fields are identified to be spheroidizing and dynamic recrystallizing controlled by self-diffusion mechanism, respectively. The microstructure observation of the deformed specimens in different domains matches very well with the optimized results.
基金Project(2011CB605505)supported by the National Basic Research Program of ChinaProject(51174233)supported by the National Natural Science Foundation of China
文摘The Ti-47Al-2Nb-2Cr-0.2W alloy sheets were obtained by hot pack rolling. The as-rolled sheet has an inhomogeneous duplex microstructure composed of elongated gamma grains and lamellar colonies. Heat treatments were conducted on the as-rolled sheets. The results show that the microstructures with different sizes and grain boundary morphologies were developed after different heat treatments. A coarse fully lamellar structure can be refined if the heating time, together with the cooling rate, is appropriately controlled. The grain growth exponent is found to be approximately 0.2, and the activation energy of grain boundary migration of the alloy is around 225 kJ/mol.
基金Funded by the National Key Natural Science Foundation of China(No.5131903ZT1)
文摘TC11 titanium alloy samples with lamellar microstructrue were compressed on a Gleeble 1500D Simulator.Compression tests were carried out at 950 ℃ and a strain rate of 0.1 s-1 with height reduction of 20%,40% and 60%,respectively.Microstruture of the compressed TC11 alloy was obeserved and analyzed by optical microscopy(OM),transmission electron microscope(TEM),electron back-scattered diffraction(EBSD).The lamellar disintegration mechanism of the TC11 titanium alloy was deduced.The results indicated that the compressive deformation promoted the phase transformation in bi-phase area.βphase layers were formed along the gliding planes inα phase,and α slivers were disintegrated into many small flakes through theα/βinterface slipping.
基金supported by the 973 project(2011CB610406,2011CB605504)NSFC project(51331005)Heilongjiang project(JC201209)
文摘TiAl-based alloys are potentially used as high-temperature structural materials with a high specific strength in the range of^900°C.However,the mechanical properties of TiAl-based alloys are extremely anisotropic with respect to the lamellar orientation of the microstructures.A balance combination of room-temperature ductility and strength can be achieved when the lamellar orientation are aligned parallel to the tensile stress direction.Lamellar orientation control of TiAl-based alloys by directional solidification technique has been widely studied in recent years.Two different directional solidification processes can be used to modify the lamellar orientation.One is a seeding technique and the other is adjusting the solidification path.This paper reviews the principles of the two methods and their progress.The influence of alloy composition and solidification parameters on lamellar orientation control is also discussed.
文摘The independent influence of microstructural features on fracture toughness of TC21alloy with lamellar microstructure was investigated.Triple heat treatments were designed to obtain lamellar microstructures with different parameters,which were characterized by OM and SEM.The size and content ofαplates were mainly determined by cooling rate from singleβphase field and solution temperature in two-phase field;while the precipitation behavior of secondaryαplatelets was dominantly controlled by aging temperature in two-phase field.The content and thickness ofαplates and the thickness of secondaryαplatelets were important microstructural features influencing the fracture toughness.Both increasing the content ofαplates and thickeningαplates(or secondaryαplatelets)could enhance the fracture toughness of TC21alloy.Based on energy consumption by the plastic zone of crack tip inαplates,a toughening mechanism for titanium alloys was proposed.
文摘AIM：To evaluate the functional and aesthetic outcomes of upper eyelid cicatricial entropion（UCE） correction using anterior lamellar recession（ALR） with addressing the associated conditions including dermatochalasis,brow ptosis,blepharoptosis,and lid retraction.METHODS：Chart review of patients with upper lid cicatricial entropion who had undergone ALR from 2013 to 2016 was reviewed.Success was defi ned as the lack of any lash in contact with the globe,no need for a second procedure,and acceptable cosmesis at the fi nal follow up.RESULTS：Sixty eight patients（97 eyelids） were operated by ALR with simultaneous correction of associated lid problems in each case when necessary.The mean followup time was 17.8 mo（range,6.0-24.0 mo）.Concomitantly,levator tucking was performed in 19 eyelids（19.6%）,upper lid retractor recession in 18 eyelids（18.6%）,and internal browpexy in 31 eyelids（32.0%）.In 95.8% of patients（95%CI：0.85-0.96）,satisfactory functional and cosmetic outcome was achieved with a single surgical procedure.CONCLUSION：Based on the principles of lamellar recession and concurrently addressing the associated lid problems,this approach is an effective and safe treatment of UCE.
基金National Natural Science Foundation of China (No. 81270979)Natural Science Foundation of Jiangsu Province, China (No.BK2012777)
文摘·AIM: To describe the initial outcomes and safety of femtosecond laser-assisted deep anterior lamellar keratoplasty(DALK) for keratoconus and post-LASIK keratectasia.·METHODS: In this non-comparative case series, 10 eyes of 9 patients underwent DALK procedures with a femtosecond laser(Carl Zeiss Meditec AG, Jena,Germany). Of the 9 patients, 7 had keratoconus and 2had post-LASIK keratectasia. A 500 kHz VisuMax femtosecond laser was used to perform corneal cuts on both donor and recipient corneas. The outcome measures were the uncorrected visual acuity(UCVA),best-corrected visual acuity(BCVA), corneal thickness,astigmatism, endothelial density count(EDC), and corneal power.·RESULTS: All eyes were successfully treated. Early postoperative evaluation showed a clear graft in all cases. Intraoperative complications included one case of a small Descemet’s membrane perforation.Postoperatively, there was one case of stromal rejection,one of loosened sutures, and one of wound dehiscence.A normal corneal pattern topography and transparency were restored, UCVA and BCVA improved significantly,and astigmatism improved slightly. There was no statistically significant decrease in EDC.· CONCLUSION: Our early results indicate that femtosecond laser-assisted deep anterior lamellar keratoplasty could improve UCVA and BCVA in patients with anterior corneal pathology. This approach shows promise as a safe and effective surgical choice in the treatment of keratoconus and post-LASIK keratectasia.
基金supported by the National Natural Science Foundation of China[grant number U1537202]the TsinghuaGeneral Motor International collaboration project[grant number 20153000354]+1 种基金the UK Royal Society through the Newton International Fellowship Schemethe National Laboratory for Information Science and Technology in Tsinghua University for access to supercomputing facilities
文摘In the present study, the influence of natural convection on the lamellar eutectic growth is determined by a phase-field-lattice Boltzmann study for Al-Cu eutectic alloy. The mass difference resulting from concentration difference led to the fluid flow, and a robust parallel and adaptive mesh refinement algorithm was employed to improve the computational efficiency without any compromising accuracy. Results show that the existence of natural convection would affect the growth undercooling and thus control the interface shape by adjusting the lamellar width. In particular, by alternating the magnitude of the solute expansion coefficient, the strength of the natural convection is changed. Corresponding microstructure patterns are discussed and compared with those under no-convection conditions.
基金financially supported by the National Natural Science Foundation of China (50975060,50901025)the National Basic Research Program of China (2011CB610406)+2 种基金the China Postdoctoral Science Foundation (201104420,20090450840)the Fundamental Research Funds for the Central Universities (HIT.BRET1.2010008)the Scientific and Technological Project in Heilongjiang Province (GZ09A206)
文摘The fracture behavior of fully lamellar γ-TiAl alloys depends on the angle between the lamellar orientation and loading axis,but the role of the presentation of grain boundary cannot be ignored.To investigate the influence of the grain boundary on the initiation and propagation of cracks,the tensile test of the alloy was conducted at room temperature with loading axis parallel and perpendicular to the lamellar orientation,respectively.The cracks adjacent to the fracture zone of the tensile specimens have been investigated to analyze the fracture behavior.Results show that the grain boundary has dual influences on the fracture behavior.When the loading axis is parallel to the lamellar orientation,cracks are preferentially initiated at and propagate along the grain boundaries.When the loading axis is perpendicular to the lamellar orientation,the grain boundaries can prevent the propagation of cracks from running across.Additionally,serrated-shape grain boundaries have a better inhibiting effect on the propagation of cracks than planar boundaries.
文摘The microstructural stability of lamellar TiAl base alloys at high temperatures was studied by conventional and high resolution transmission electron microscopy. The influence of substructures on the thermal stability of lamellar structure was emphasized. These substructures produced by thermal mechanical treatments include the interfacial dislocations and ledges, the subgrain boundaries, the impinged T(Q) twins and misorientated lamellar interfaces. The microstructural change of three kinds of lamellar TiAl base alloys containing differents type and densities of substructures were compared during exposure at 800~1 000 ℃. It was found that the existence of such substructures could accelerate the degeneration of lamellar structure, leading to the rapid necking and break up of α 2 plates, the coarsening of γ plates, and the formation of new γ grains. As a result, the lamellar structure with substructures started to degenerate after thermal exposure at 800℃ for 4.5 h. While only slight coarsening was observed at the colony boundaries in the lamellar structure without substructures even after exposure at 900 ℃ for 7 d.
基金supported by National Natural Science Foundation of China(Grant Nos.50975060,50901025)the National Basic Research Program of China(Grant No.2011CB610406)+2 种基金the China Postdoctoral Science Foundation(Grant Nos.201104420,20090450840)the Fundamental Research Funds for the Central Universities(Grant No.HIT.BRET1.2010008)Scientific and Technological Project in Heilongjiang Province(Grant No.GZ09A206)
文摘The fracture behavior of fully lamellar binary γ-TiAI alloys is extremely anisotropic with respect to the lamellar orientation. For the fully lamellar Ti-46Al-0.5W-0.5Si alloy, the existence of silicide clusters plays a critical role on the fracture behavior. In the present study, tensile test and three point bending test were performed at room temperature with the loading axis parallel and perpendicular to the lamellar orientation, respectively. To investigate the influence of silicide clusters on the initiation and propagation of cracks, the fracture surface and the cracks adjacent to the fracture zone of the specimens have been analyzed. Results show that the fracture process is related to the morphology and distribution of the silicide clusters. Crack preferentially initiates at and propagates along the interface of silicide and a2/7 lamellar with the loading axis perpendicular to the length direction of silicide. While the silicide can prevent the propagation of cracks from running across with the crack growth direction perpendicular to the length direction of silicide.
文摘Creep experiments have been conducted on five powder metallurgy TiAl alloys with fine grains (65～80 μm), fine lamellar spacings (0.1～0.16 μm), and different compositions [Ti 47Al(+Cr, Nb, Ta, W, Si)] at temperatures of 760 ℃ and 815 ℃ and stresses from 35 to 723 MPa. Results show that at a given lamellar spacing 1% Nb(mole fraction) with 1% Ta and replacing 0.2% Ta with 0.2% W induced little effect, but addition of 0.3% Si decreased the creep resistance by a factor of 3～4 under otherwise identical conditions. These different effects of different alloying elements are interpreted in terms of the interaction of alloy segregants with misfit and/or misorientaion dislocations at the lamellar interface. That is, the interaction retards or facilitates the climb of interfacial dislocations, which is rate controlling during creep, depending on the size of the segregants relative to the host atoms.
基金Supported by the Innovation Project of Shandong Academy of Medical Sciences。
文摘AIM: To compare long-term postoperative outcomes of manual and femtosecond assisted corneal trephination in deep anterior lamellar keratoplasty(FS-DALK) for keratoconus.METHODS: In the retrospective study, 17 consecutive eyes that underwent vertical side cut incision FS-DALK and 22 eyes that underwent trephine incision DALK were collected over a 2-year period. Main measurements included postoperative uncorrected-visual acuity(UCVA), corrected distance visual acuity(CDVA), refractive sphere and cylinder, manifest refraction spherical equivalent(MRSE), flat and steep corneal keratometry(K1 and K2), endothelial cell density(ECD), and time of epithelium healing and suture removal.RESULTS: Groups were comparable for diagnosis and preoperative visual acuity. Follow-up averaged 23 mo(range, 12-36 mo). At 12 mo, the mean UCVA was better in the manual-DALK group(P=0.039), and the refractive sphere was lower in the FS-DALK group(P=0.040). MRSE between groups differed at 1, 6, and 12 mo postoperatively(P=0.047, 0.025, 0.042, respectively). Mean CDVA, cylinder, K1, K2,corneal astigmatism, ECD, and time of epithelium healing were similar between groups. Stability of MRSE, ECD, and K1 returned sooner after FS-DALK. Initial loosened suture removal time was earlier in the manual-DALK group(P=0.042) while complete suture removal time was similar(P=0.122).CONCLUSION: Manual and femtosecond assisted corneal trephination in DALK are options for advanced keratoconus. FS-DALK do not result in improved visual acuity but it is more stable during the follow-up period. FSDALK in the present form show limited benefit, so surgical design and parameters still need to be optimized and explored.
