Sutured scleral fixation of existing subluxated/dislocated acrylic one-piece intraocular lenses

AIM:To evaluate the visual and refractive outcomes in cases after sutured scleral fixation of existing subluxated or dislocated acrylic one-piece intraocular lenses(IOLs).METHODS:This study retrospectively enrolled a consecutive series of patients who underwent a surgery of sutured existing subluxated or dislocated IOLs from October 2018 to June 2020.All patients underwent comprehensive preoperative and postoperative ophthalmologic examination,and data were collected including age,sex,surgical indications,best-corrected visual acuity,refractive error,intraocular pressure.Presence of intraoperative and postoperative surgical complications was documented.RESULTS:A total of 20 consecutive cases were enrolled for analysis with mean final follow-up period 9.8±5.3mo.Visual acuity improved from a mean of 0.35(0.46±0.32 logMAR)preoperatively to 0.61(0.21±0.18 logMAR)at the 3-month follow-up(P=0.002).The mean amount of preoperative keratometric astigmatism and total postoperative refractive astigmatism was-1.24±0.80 diopters(D)and-1.42±0.97 D,respectively.There was no statistically significant difference between preoperative and postoperative astigmatism(P=0.156).The mean IOL-induced astigmatism was-0.23±0.53 D.The mean spherical equivalent at the 3-month follow-up was-0.1±0.94 D.No major complications were noted during the follow-up period.CONCLUSION:Surgical techniques using sutured scleral fixation of existing subluxated or dislocated acrylic one-piece IOLs result in favorable visual and refractive outcomes without major complications.

Posterior segment nucleotomy for dislocated sclerotic cataractous lens using chandelier endoilluminator and sharp tipped chopper

· AIM: To describe a new surgical technique for managing dislocated sclerotic cataractous lens.· METHODS: Six patients with advanced posteriorly dislocated cataracts were operated at a tertiary care centre and analyzed retrospectively. After standard 3 port23 G pars plana vitrectomy and perfluorocarbon liquid(PFCL) injection, the dislocated white cataract was held with occlusion using phaco fragmatome and then chopped into smaller pieces with a sharp tipped chopper using 25 G chandelier endoilluminator. Each piece was emulsified individually. Following aspiration of PFCL,Fluid Air Exchange was done in all the cases and surgery completed uneventfully.·RESULTS: Best corrected visual acuity(BCVA) in all the patients was better than 6/12 after one month of follow up. No serious complications were noted till minimum 6mo of follow up.·CONCLUSION: Four port posterior segment nucleotomy with a chandelier endoilluminator, fragmatome and a chopper appears to be a safe, easy and effective procedure for managing dislocated sclerotic cataractous nuclei. Ultrasonic energy used and adverse thermal effects of the fragmatome on the sclera may be lesser.

Some Common Fixed Point Theorems for Four Mappings in Dislocated Metric Space

In this article, we establish some common fixed point theorems for two pairs of weakly compatible mappings with (E. A.) and (CLR) property in dislocated metric space which generalize and extend some similar results in the literature.

Some Integral Type Fixed Point Theorems in Dislocated Metric Space

In this article, we establish a common fixed point theorem satisfying integral type contractive condition for two pairs of weakly compatible mappings with E. A. property and also generalize Theorem (2) of B.E. Rhoades [1] in dislocated metric space.

General hybrid projective complete dislocated synchronization with non-derivative and derivative coupling based on parameter identification in several chaotic and hyperchaotic systems

According to the Lyapunov stability theorem, a new general hybrid projective complete dislocated synchronization scheme with non-derivative and derivative coupling based on parameter identification is proposed under the framework of drive-response systems. Every state variable of the response system equals the summation of the hybrid drive systems in the previous hybrid synchronization. However, every state variable of the drive system equals the summation of the hybrid response systems while evolving with time in our method. Complete synchronization, hybrid dislocated synchronization, projective synchronization, non-derivative and derivative coupling, and parameter identification are included as its special item. The Lorenz chaotic system, Rssler chaotic system, memristor chaotic oscillator system, and hyperchaotic Lü system are discussed to show the effectiveness of the proposed methods.

Dislocated Soft Metric Space with Soft Fixed Point Theorems

In the present paper, we define Dislocated Soft Metric Space and discuss about the existence and uniqueness of soft fixed point of a cyclic mapping in soft dislocated metric space. We also prove the unique soft fixed point theorems of a cyclic mapping in the context of dislocated soft metric space. Examples are given for support of the results.

On Dislocated Metric Topology

In this paper, we give a comment on the dislocated-neighbourhood systems due to Hitzler and Seda [1]. Also, we recover the open sets of the dislocated topology.

Treatment of traumatic globe dislocated completely into the maxillary sinus

Dear Sir, I am Dr. Bei Xu, from Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, Hunan Province, China. I want to present a rare case of the treatment of traumatic globe dislocated completely into the maxillary sinus. A 46-year-old female was admitted to emergency unit due to traffic accident, presenting disturbance of consciousness for nine hours.

23-Gauge Pars Plana Vitrectomy Alone by a Bimanual Technique for the Removal of Dense Posteriorly Dislocated Crystalline Lens

Background: We sought to verify the efficacy and safety of transconjunctival 23-gauge pars plana vitrectomy (PPV) alone by our bimanual technique for the removal of dense posteriorly dislocated crystalline lens. Methods: A retrospective, noncomparative, interventional study of 31 consecutive cases of patients who underwent 23-gauge PPV alone for the removal of dense posteriorly dislocated crystalline lens following complicated cataract surgeries using our bimanual technique was conducted. The main outcomes measured included best-corrected visual acuity (BCVA), preoperative intraocular pressure (IOP), postoperative IOP and postoperative complications. Results: In all 31 cases included in this study, those dense posteriorly dislocated crystalline lenses were successfully removed. The enrolled patients consisted of 17 males and 14 females with a mean age of (75.84 ± 6.17) years (range 59 - 90). The mean follow-up length was (7.61 ± 1.87) months with a range of 6 months to 1 year. The mean preoperative BCVA was 0.22 ± 0.11 logMAR system, and the postoperative BCVA was 0.33 ± 0.07 logMAR system after 6 months of follow-up. The mean operative time was 46.32 ± 4.80 minutes with a range of 38.00 to 57.00 minutes. All of the conjunctival incisions self-closed within the first week with no wound leakage or hemorrhage. The postoperative complications were relatively rare. Conclusions: The removal of dense posteriorly dislocated crystalline lens might be a challenge for micro-incision vitrectomy. Our bimanual technique was proved to be an effective and safe method for those particular dense lenses using 23-gauge alone.

综合征性寰枢椎脱位的临床特点及诊治进展

寰枢椎脱位(atlantoaxial dislocation,AAD)是寰枢椎不稳定(atlantoaxial instability,AAI)进行性加重最终导致寰枢关节对应关系发生错位的一种解剖状态,是脊柱外科严重的致残性疾病。Charles Bell于1830年首次记录了AAD,Pierre Grisel描述了一系列以C1-C2关节脱位为表现的咽炎和斜颈患者[1]。

儿童发育性髋关节发育不良

发育性髋关节发育不良(developmental dysplasia of the hip,DDH)是儿童常见疾病之一,包括髋白发育不良、髋关节半脱位及髋关节脱位。髋关节超声检查的广泛应用,使DDH的定义涵盖了更大的范围:未成熟的髋关节、轻度髋白发育不良的髋关节、不稳定(可脱位或可半脱位)的髋关节、半脱位的髋关节和完全脱位的髋关节1992年北美骨科年会将先天性髋脱位(congenital dislocation of the hip,CDH)更名为DDH,更准确地表明了该病的特点。

Complication rates after direct anterior vs posterior approach for hip hemiarthroplasty in elderly individuals with femoral neck fractures

BACKGROUND Dislocation rates after hemiarthroplasty reportedly vary from 1%to 17%.This serious complication is associated with increased morbidity and mortality rates.Approaches to this surgery are still debated,with no consensus regarding the superiority of any single approach.AIM To compare early postoperative complications after implementing the direct anterior and posterior approaches(PL)for hip hemiarthroplasty after femoral neck fractures.METHODS This is a comparative,retrospective,single-center cohort study conducted at a university hospital.Between March 2008 and December 2018,273 patients(a total of 280 hips)underwent bipolar hemiarthroplasties(n=280)for displaced femoral neck fractures using either the PL(n=171)or the minimally invasive direct anterior approach(DAA)(n=109).The choice of approach was related to the surgeons’practices;the implant types were similar and unrelated to the approach.Dislocation rates and other complications were reviewed after a minimum followup of 6 mo.RESULTS Both treatment groups had similarly aged patients(mean age:82 years),sex ratios,patient body mass indexes,and patient comorbidities.Surgical data(surgery delay time,operative time,and blood loss volume)did not differ significantly between the groups.The 30 d mortality rate was higher in the PL group(9.9%)than in the DAA group(3.7%),but the difference was not statistically significant(P=0.052).Among the one-month survivors,a significantly higher rate of dislocation was observed in the PL group(14/154;9.1%)than in the DAA group(0/105;0%)(P=0.002).Of the 14 patients with dislocation,8 underwent revision surgery for recurrent instability(posterior group),and one of them had 2 additional procedures due to a deep infection.The rate of other complications(e.g.,perioperative and early postoperative periprosthetic fractures and infection-related complications)did not differ significantly between the groups.CONCLUSION These findings suggest that the DAA to bipolar hemiarthroplasty for patients with femoral neck fractures is associated with a lower dislocation rate(<1%)than the PL.

High density dislocations enhance creep ageing response and mechanical properties in 2195 alloy sheet

The creep strain of conventionally treated 2195 alloy is very low,increasing the difficulty of manufacturing Al-Cu-Li alloy sheet parts by creep age forming.Therefore,finding a solution to improve the creep formability of Al-Cu-Li alloy is vital.A thorough comparison of the effects of cryo-deformation and ambient temperature large pre-deformation(LPD)on the creep ageing response in the 2195 alloy sheet at 160℃with different stresses has been made.The evolution of dislocations and precipitates during creep ageing of LPD alloys are revealed by X-ray diffraction and transmission electron microscopy.High-quality 2195 alloy sheet largely pre-deformed by 80%without edge-cracking is obtained by cryo-rolling at liquid nitrogen temperature,while severe edge-cracking occurs during room temperature rolling.The creep formability and strength of the 2195 alloy are both enhanced by introducing pre-existing dislocations with a density over 1.4×10^(15)m^(−2).At 160℃and 150 MPa,creep strain and creep-aged strength generally increases by 4−6 times and 30−50 MPa in the LPD sample,respectively,compared to conventional T3 alloy counterpart.The elongation of creep-aged LPD sample is low but remains relevant for application.The high-density dislocations,though existing in the form of dislocation tangles,promote the formation of refined T1 precipitates with a uniform dispersion.

Enhanced creep resistance in Mg-Y-Nd alloy via regulating prior thermo-mechanical treatment

In this study,the tensile creep behavior of a hot-rolled Mg-4Y-3.5Nd alloy subjected to different prior thermo-mechanical treatments was investigated at 220℃.Five groups of samples were prepared using different combinations of the solid solution(S),aging treatment at 220℃ for 30 h(A),and hot compression at 490℃ to a true strain of 0.25(C).The abbreviations for the samples are S,SA,SC,SAC,and SCA.Upon examining the yield strength and creep resistance,it was found that creep resistance could not be directly predicted by the yield strength.The stability of the deformation bands(DBs)induced by prior thermo-mechanical treatment plays an important role in determining the creep resistance.The dislocation of the DBs and demonstrated the best creep resistance in the SAC sample,which were prepared using a solid solution,aging treatment,and subsequent hot compression.However,despite the highest yield strength,frequent dislocation motions destroyed the stability of the DBs and deteriorated the creep resistance of the SCA sample,which were prepared using a solid solution,hot compression,and subsequent aging treatment.Among the thermo-mechanical treatments used in this study,the application of aging treatment was important to obtain the resultant creep resistance.When the aging treatment was performed prior to hot compression,the creep resistance could be further enhanced based only on hot compression.Accordingly,the sequence from the strongest to the weakest creep resistance was SAC>SC>S>SCA>SA.

Rapid drop in ductility of the bimodal-structured Mg-15Gd binary alloy during early aging

A bimodal-structured Mg^(-1)5Gd binary alloy with 45%volume fraction of elongated grains and 55%of dynamically recrystallized(DRXed)grains is fabricated by the extrusion process.The precipitating behavior correlating with the evolution of mechanical properties is systematically characterized during the subsequent aging treatment at 200°C.The extruded alloy presents an outstanding strength with tensile yield strength of 466 MPa and ultimate tensile strength of 500 MPa at peak aging condition,while the elongation drops from 9.2%in extrusion state to 3.1%.It is found there obviously exist a rapidly decreasing range of ductility at the early stage of aging.Just during this time,the nano precipitates form preferentially at lamellar dislocation boundaries(LDBs)within the elongated grains,but there is no dense and uniform precipitation in the matrix.The results suggest that the low elongation in the aged Mg^(-1)5Gd alloy is mainly attributed to the nano precipitates prior formed at the LDBs with a high density in the elongated grains.The related mechanism has been clarified.

Effect of Pre-strain on Microstructure and Stamping Performance of High-strength Low-alloy Steel

In this study,pre-strain ranging from 0 to 0.12 was applied through uniaxial tension on high-strength low-alloy(HSLA)specimens with four kinds of grain size.Effect of pre-strain and grain size on me-chanical property was investigated through tensile tests.Microstructures of the pre-strained and tensile tested samples were analyzed,respectively.The 30.8°v-bending and following flattening,as well as Erichson cupping tests,were performed on the pre-strained samples.Results show the elongation ratio of grain and dislocation density increases with pre-strain.Yielding platform is removed when pre-strain is larger than 0.06 while yielding plateau period decreases with pre-strain less than 0.06 due to reduction of pinning effect.The 30.8°v-bending and the following flattening tests are successfully accomplished on all the pre-strained samples with different grain size.Decrease in grain size,along with increase in pre-strain,causes increase in strength and decrease in elongation rate as well as cupping value.Pre-strain causes very slight effect on bending ability,much less than that on mechanical property and cupping test value.Reciprocal impact of the pre-strain and grain size on HSLA steel deformability is inconspicuous.

A molecular dynamics study on mechanical performance and deformation mechanisms in nanotwinned NiCo-based alloys with nano-precipitates under high temperatures

Molecular dynamics simulations are performed to investigate the mechanical behavior of nanotwinned NiCo-based alloys containing coherent L12 nano-precipitates at different temperatures,as well as the interactions between the dislocations and nano-precipitates within the nanotwins.The simulation results demonstrate that both the yield stress and flow stress in the nanotwinned NiCo-based alloys with nano-precipitates decrease as the temperature rises,because the higher temperatures lead to the generation of more defects during yielding and lower dislocation density during plastic deformation.Moreover,the coherent L12 phase exhibits excellent thermal stability,which enables the hinderance of dislocation motion at elevated temperatures via the wrapping and cutting mechanisms of dislocations.The synergistic effect of nanotwins and nano-precipitates results in more significant strengthening behavior in the nanotwinned NiCo-based alloys under high temperatures.In addition,the high-temperature mechanical behavior of nanotwinned NiCo-based alloys with nano-precipitates is sensitive to the size and volume fraction of the microstructures.These findings could be helpful for the design of nanotwins and nano-precipitates to improve the high-temperature mechanical properties of NiCo-based alloys.

Investigation of reflection anisotropy induced by micropipe defects on the surface of a 4H-SiC single crystal using scanning anisotropy microscopy

Optical reflection anisotropy microscopy mappings of micropipe defects on the surface of a 4H-SiC single crystal are studied by the scanning anisotropy microscopy(SAM)system.The reflection anisotropy(RA)image with a'butterfly pattern'is obtained around the micropipes by SAM.The RA image of the edge dislocations is theoretically simulated based on dislocation theory and the photoelastic principle.By comparing with the Raman spectrum,it is verified that the micropipes consist of edge dislocations.The different patterns of the RA images are due to the different orientations of the Burgers vectors.Besides,the strain distribution of the micropipes is also deduced.One can identify the dislocation type,the direction of the Burgers vector and the optical anisotropy from the RA image by using SAM.Therefore,SAM is an ideal tool to measure the optical anisotropy induced by the strain field around a defect.

Review on the plastic instability of medium -Mn steels for identifying the formation mechanisms of Lüders and Portevin -Le Chatelier bands

Plastic instability,including both the discontinuous yielding and stress serrations,has been frequently observed during the tensile deformation of medium-Mn steels(MMnS)and has been intensively studied in recent years.Unfortunately,research results are controversial,and no consensus has been achieved regarding the topic.Here,we first summarize all the possible factors that affect the yielding and flow stress serrations in MMnS,including the morphology and stability of austenite,the feature of the phase interface,and the deformation parameters.Then,we propose a universal mechanism to explain the conflicting experimental results.We conclude that the discontinuous yielding can be attributed to the lack of mobile dislocation before deformation and the rapid dislocation multiplication at the beginning of plastic deformation.Meanwhile,the results show that the stress serrations are formed due to the pinning and depinning between dislocations and interstitial atoms in austenite.Strain-induced martensitic transformation,influenced by the mechanical stability of austenite grain and deformation parameters,should not be the intrinsic cause of plastic instability.However,it can intensify or weaken the discontinuous yielding and the stress serrations by affecting the mobility and density of dislocations,as well as the interaction between the interstitial atoms and dislocations in austenite grains.

Roughness characterization and shearing dislocation failure for rock-backfill interface

Shearing dislocation is a common failure type for rock–backfill interfaces because of backfill sedimentation and rock strata movement in backfill mining goaf.This paper designed a test method for rock–backfill shearing dislocation.Using digital image techno-logy and three-dimensional(3D)laser morphology scanning techniques,a set of 3D models with rough joint surfaces was established.Further,the mechanical behavior of rock–backfill shearing dislocation was investigated using a direct shear test.The effects of interface roughness on the shear–displacement curve and failure characteristics of rock–backfill specimens were considered.The 3D fractal dimen-sion,profile line joint roughness coefficient(JRC),profile line two-dimensional fractal dimension,and the surface curvature of the frac-tures were obtained.The correlation characterization of surface roughness was then analyzed,and the shear strength could be measured and calculated using JRC.The results showed the following:there were three failure threshold value points in rock–backfill shearing dis-location:30%–50%displacement before the peak,70%–90%displacement before the peak,and 100%displacement before the peak to post-peak,which could be a sign for rock–backfill shearing dislocation failure.The surface JRC could be used to judge the rock–backfill shearing dislocation failure,including post-peak sliding,uniform variations,and gradient change,corresponding to rock–backfill disloca-tion failure on the field site.The research reveals the damage mechanism for rock–backfill complexes based on the free joint surface,fills the gap of existing shearing theoretical systems for isomerism complexes,and provides a theoretical basis for the prevention and control of possible disasters in backfill mining.