Improving fatigue properties of normal direction ultrasonic vibration assisted face grinding Inconel 718 by regulating machined surface integrity

Fatigue properties are crucial for critical aero-engine components in extreme serviceenvironments,which are significantly affected by surface integrity(SI)indexes(especially surface topography,residual stressσ_(res),and microhardness)after machining processes.Normal-direction ultrasonic vibration-assisted face grinding(ND-UVAFG)has advantages in improving the machinability of Inconel 718,but there is a competitive relationship between higher compressiveσ_(res)and higher surface roughness R_(a)in affecting fatigue strength.The lack of a quantitative relationship between multiple SI indexes and fatigue strength makes theindeterminacy of a regulatory strategy for improving fatigue properties.In this work,a model of fatigue strength(σ_f)_(sur)considering multiple SI indexes was developed.Then,high-cycle fatigue tests were carried out on Inconel 718 samples with different SI characteristics,and the influence of ND-UVAFG process parameters on SI was analyzed.Based on SI indexes data,the(σ_f)_(sur)distribution in the grinding surface layer for ND-UVAFG Inconel 718 samples was determined using the developed model,and then the fatigue crack initiation(FCI)sites were furtherpredicted.The predicted FCI sites corresponded well with the experimental results,therebyverifying this model.A strategy for improving the fatigue life was proposed in this work,which was to transfer the fatigue source from the machined surface to the bulk material by controlling the SI indexes.Finally,a critical condition of SI indexes that FCI sites appeared on the surface or in bulk material was given by fitting the predicted results.According to the critical condition,an SI field where FCI sites appeared in the bulk material could be obtained.In this field,thefatigue life of Inconel 718 samples could be improved by approximately 140%.

Enhanced Extreme Ultraviolet Free Induction Decay Emission Assisted by Attosecond Pulses

We demonstrate the extreme ultraviolet free induction decay emission that can be significantly enhanced by employing isolated attosecond pulses.The near infrared pulses are applied to excite the neon atoms into Rydberg states coherently,and isolated attosecond pulses are used to manipulate populations of the Rydberg states and the subsequent free induction decay process.The time resolved experimental measurement of dependence of the resonance emission yield would help to understand the buildup dynamics of population of excited states.The enhancement assisted by attosecond pulses can serve as a mechanism to develop high-flux extreme ultraviolet light sources.

Grindability Evaluation of Ultrasonic Assisted Grinding of Silicon Nitride Ceramic Using Minimum Quantity Lubrication Based SiO_(2)Nanofluid

Minimum quantity Lubrication(MQL)is a sustainable lubrication system that is famous in many machining systems.It involve the spray of an infinitesimal amount of mist-like lubricants during machining processes.The MQL system is affirmed to exhibit an excellent machining performance,and it is highly economical.The nanofluids are understood to exhibit excellent lubricity and heat evacuation capability,compared to pure oil-based MQL system.Studies have shown that the surface quality and amount of energy expended in the grinding operations can be reduced considerably due to the positive effect of these nanofluids.This work presents an experimental study on the tribological performance of SiO_(2)nanofluid during grinding of Si_(3)N_(4)ceramic.The effect different grinding modes and lubrication systems during the grinding operation was also analyzed.Different concentrations of the SiO_(2)nanofluid was manufactured using canola,corn and sunflower oils.The quantitative evaluation of the grinding process was done based on the amount of grinding forces,specific grinding energy,frictional coefficient,and surface integrity.It was found that the canola oil exhibits optimal lubrication performance compared to corn oil,sunflower oil,and traditional lubrication systems.Additionally,the introduction of ultrasonic vibrations with the SiO_(2)nanofluid in MQL system was found to reduce the specific grinding energy,normal grinding forces,tangential grinding forces,and surface roughness by 65%,57%,65%,and 18%respectively.Finally,regression analysis was used to obtain an optimum parameter combinations.The observations from this work will aid the smooth transition towards ecofriendly and sustainable machining of engineering ceramics.

Clinical Study of Tianji Robotic-Assisted Surgery for Upper Cervical Spine Fractures

Object: To compare the safety, clinical efficacy, and complication rate of “Tianji” robot-assisted surgery with traditional open surgery in the treatment of cervical vertebrae fracture. Methods: 60 patients with upper cervical vertebrae fracture admitted to Baise People’s Hospital between November 2018 and April 2024 were retrospectively analyzed. Among these patients, 29 underwent “Tianji” robot-assisted surgery (Robot group), and 31 underwent traditional C-arm fluoroscopy-assisted open surgery (Open group). Statistical analysis of the data was performed using SPSS 27.0 software to compare general data (gender, age, BMI), preoperative and postoperative visual analogue scale (VAS) scores, neck disability index (NDI), intraoperative blood loss, accuracy of screw placement on imaging, and the number of complications in both groups for comprehensive evaluation. A P value < 0.05 was deemed to have achieved statistical significance. Results: There was no significant difference in preoperative VAS scores between the two groups (Robot group: 8.34 ± 0.61;Open group: 8.26 ± 0.68, P = 0.317). There was also no significant difference in VAS scores at 1 week postoperatively (Robot group: 6.90 ± 0.31;Open group: 6.94 ± 0.36, P = 0.3237). Preoperative NDI scores showed no significant difference between the two groups (Robot group: 43.31 ± 2.67;Open group: 43.84 ± 2.67, P = 0.2227), and the difference in NDI scores at 1 week postoperatively was also not significant (Robot group: 35.69 ± 4.24;Open group: 37.35 ± 3.48, P = 0.0509). Intraoperative blood loss in the Robot group was significantly lower than in the Open group (246.21 ± 209 ml vs 380.65 ± 328.04 ml, P = 0.0308), with a statistically significant difference. The operation time was longer in the Robot group (3.75 ± 0.74 h) compared to the Open group (2.74 ± 0.86 h). In terms of screw placement accuracy, the Robot group had a higher accuracy rate for Class A screws compared to the Open group (102 screws vs 94 screws, P = 0.0487), and the accuracy rate for Class B screws was also higher in the Robot group (13 screws vs 29 screws, P = 0.0333), with both differences being statistically significant. There was no significant difference in the number of complications between the two groups (Robot group: 8 cases;Open group: 10 cases, P = 0.6931). Conclusion: Patients treated with “Tianji” robot-assisted surgery for upper cervical vertebrae fracture had lower intraoperative blood loss and higher screw placement accuracy compared to those undergoing traditional C-arm fluoroscopy-assisted open surgery, indicating that this robot-assisted surgery can effectively reduce intraoperative blood loss and improve screw placement accuracy.

Comparison efficacy and safety of total laparoscopic gastrectomy and laparoscopically assisted total gastrectomy in treatment of gastric cancer

BACKGROUND The development of laparoscopic technology has provided a new choice for surgery of gastric cancer(GC),but the advantages and disadvantages of laparoscopic total gastrectomy(LTG)and laparoscopic-assisted total gastrectomy(LATG)in treatment effect and safety are still controversial.The purpose of this study is to compare the efficacy and safety of the two methods in the treatment of GC,and to provide a basis for clinical decision-making.AIM To compare the efficacy of totally LTG(TLTG)and LATG in the context of radical gastrectomy for GC.Additionally,we investigated the safety and feasibility of the total laparoscopic esophagojejunostomy technique.METHODS Literature on comparative studies of the above two surgical methods for GC(TLTG group and LATG group)published before September 2022 were searched in the PubMed,Web of Science,Wanfang Database,CNKI,and other Chinese and English databases.In addition,the following search keywords were used:Gastric cancer,total gastrectomy,total laparoscopy,laparoscopy-assisted,esophagojejunal anastomosis,gastric/stomach cancer,total gastrectomy,totally/completely laparoscopic,laparoscopic assisted/laparoscopy assisted/laparoscopically assisted,and esophagojejunostomy/esophagojejunal anastomosis.Review Manager 5.3 software was used for the meta-analysis after two researchers independently screened the literature,extracted the data,and evaluated the risk of bias in the included studies.RESULTS After layer-by-layer screening,258 pieces of literature were recovered,and 11 of those pieces were eventually included.This resulted in a sample size of 2421 instances,with 1115 cases falling into the TLTG group and 1306 cases into the LATG group.Age or sex differences between the two groups were not statistically significant,according to the meta-analysis,however the average body mass index of the TLTG group was considerably higher than that of the LATG group(P=0.01).Compared with those in the LATG group,the incision length in the TLTG group was significantly shorter(P<0.001),the amount of intraoperative blood loss was significantly lower(P=0.003),the number of lymph nodes removed was significantly greater(P=0.04),and the time of first postoperative feeding and postoperative hospitalization were also significantly shorter(P=0.03 and 0.02,respectively).There were no significant differences in tumor size,length of proximal incisal margin,total operation time,anastomotic time,postoperative pain score,postoperative anal exhaust time,postoperative anastomosis-related complications(including anastomotic fistula,anastomotic stenosis,and anastomotic hemorrhage),or overall postoperative complication rate(P>0.05).CONCLUSION TLTG and esophagojejunostomy are safe and feasible.Compared with LATG,TLTG has the advantages of less trauma,less bleeding,easier access to lymph nodes,and faster postoperative recovery,and TLTG is also suitable for obese patients.

High performance micromachining of sapphire by laser induced plasma assisted ablation(LIPAA)using GHz burst mode femtosecond pulses

GHz burst-mode femtosecond(fs)laser,which emits a series of pulse trains with extremely short intervals of several hundred picoseconds,provides distinct characteristics in materials processing as compared with the conventional irradiation scheme of fs laser(single-pulse mode).In this paper,we take advantage of the moderate pulse interval of 205 ps(4.88 GHz)in the burst pulse for high-quality and high-efficiency micromachining of single crystalline sapphire by laser induced plasma assisted ablation(LIPAA).Specifically,the preceding pulses in the burst generate plasma by ablation of copper placed behind the sapphire substrate,which interacts with the subsequent pulses to induce ablation at the rear surface of sapphire substrates.As a result,not only the ablation quality but also the ablation efficiency and the fabrication resolution are greatly improved compared to the other schemes including single-pulse mode fs laser direct ablation,single-pulse mode fs-LIPAA,and nanosecond-LIPAA.

Endoscopic vacuum assisted closure therapy for esophagopericardial fistula in a 16-year-old male:A case report

BACKGROUND Esophagopericardial fistula(EPF)is a rare,life-threatening condition with limited scientific literature and no established management guidelines.This case report highlights a successful multidisciplinary approach and the innovative use of endoscopic vacuum assisted closure(endoVAC)therapy in treating this complex condition.CASE SUMMARY A 16-year-old male with a history of esophageal atresia and colon interposition presented with progressive chest pain,fever,and dyspnea.Imaging revealed an EPF with associated pleural and pericardial effusions.Initial management with an esophageal stent failed,prompting the use of an endoVAC system.The patient underwent multiple endoVAC device changes and received broad-spectrum antibiotics and nutritional support.The fistula successfully closed,and the patient recovered,demonstrating no new symptoms at a 6-month follow-up.CONCLUSION EndoVAC therapy can effectively manage EPF,providing a minimally invasive treatment option.

The Impact of Seasonal Variation on Clinical Pregnancy and Live Birth Rates in Assisted Reproductive Technology: A Retrospective Cohort Study in Hainan

Objective:To investigate the influence of season on live birth and clinical pregnancy rates,as well as assisted reproductive technology(ART)outcomes,in the Hainan region.Methods:Patients were categorized into four groups based on the dates of artificial insemination and transplantation:spring,summer,autumn,or winter.The main outcome measures were clinical pregnancy rates and live birth rates.Secondary outcomes included body mass index(BMI),oocyte number,two pronuclei(2PN)cleavage rate,total gonadotropin(Gn)dosage and days,age,2PN fertilization rate,sperm concentration,sperm PR rate,anti-Müllerian hormone(AMH),and endometrial thickness.Outpatient semen quality indicators included sperm PR rate,total sperm count,sperm concentration,and total sperm motility.Results:This retrospective cohort study analyzed 2,016 artificial insemination cycles and 1,783 ovarian retrieval cycles from January 2017 to October 2022,and assessed the semen quality of 6,651 outpatients from May 2017 to October 2022.In artificial insemination cycles,sperm PR rate and clinical pregnancy rate were highest in winter,with a statistically significant difference between groups(P<0.05).Clinical pregnancy rate was influenced by both age and sperm PR rate(P<0.05).In ovarian retrieval cycles,the winter group had significantly higher clinical pregnancy,2PN fertilization,and 2PN cleavage rates than the other groups.The autumn group had higher live birth rates,though not significantly different.Additionally,winter months showed higher total sperm concentration and total sperm number compared to other seasons.Conclusion:Seasonality affected clinical pregnancy and live birth rates in artificial insemination cycles but not in ovarian retrieval cycles in the Hainan region.These findings suggest that while there is no need to choose a specific season for ovarian retrieval cycles,artificial insemination in winter may be preferable for patients.

Mass-Based Environmental Factor and Energy Assessment of Microwave-Assisted Synthesized Transition Metal Nanostructures

This paper describes mass-based energy phase-space projection of microwave-assisted synthesis of transition metals (zinc oxide, palladium, silver, platinum, and gold) nanostructures. The projection uses process energy budget (measured in kJ) on the horizontal axes and process density (measured in kJg−1) on the vertical axes. These two axes allow both mass usage efficiency (Environmental-Factor) and energy efficiency to be evaluated for a range of microwave applicator and metal synthesis. The metrics are allied to the: second, sixth and eleventh principle of the twelve principle of Green Chemistry. This analytical approach to microwave synthesis (widely considered as a useful Green Chemistry energy source) allows a quantified dynamic environmental quotient to be given to renewable plant-based biomass associated with the reduction of the metal precursors. Thus allowing a degree of quantification of claimed “eco-friendly” and “sustainable” synthesis with regard to waste production and energy usage.

Impact of the Rapid Recovery Concept on Complications and Patient Quality of Life in the Perioperative Nursing of Robot-Assisted Radical Oesophageal Cancer

Aim: This study evaluates the impact of Enhanced Recovery After Surgery (ERAS) nursing on postoperative complications and quality of life in patients undergoing robot-assisted minimally invasive esophagectomy (RAMIE). Methods: A total of 150 patients who underwent RAMIE from January 2020 to January 2022 at our hospital were randomly assigned to either the observation group or the control group, with 75 patients in each. The control group received standard perioperative management and nursing care, while the observation group was treated with ERAS nursing strategies. Interventions continued until discharge, and outcomes such as postoperative complications, quality of life, and nutritional status were compared between the groups. Results: The observation group exhibited a significantly lower incidence of postoperative adverse reactions compared to the control group (P ionally, all dimension scores of the Short-Form 36 Health Survey (SF-36), including the total score, were higher in the observation group (P < 0.05). Furthermore, the Nutritional Risk Screening (NRS) scores for impaired nutritional status and disease severity, along with the total NRS score, were significantly lower in the observation group compared to the control group (P Conclusion: Implementing ERAS nursing in the perioperative care of patients undergoing RAMIE is associated with reduced postoperative complications and enhanced postoperative quality of life and nutritional status. .

Evaluation of Functional and Radiological Outcome of Arthroscopic-Assisted Anatomical Coracoclavicular (CC) and Acromioclavicular (AC) Ligament Reconstruction in Chronic AC Joint Dislocation

Introduction: Acromioclavicular (AC) joint dislocation is a common shoulder injury, comprising 9% - 12% of shoulder girdle injuries. Optimal management remains challenging, with treatment decisions guided by the Rockwood classification system. Controversies surround grade III injuries, necessitating further classification. Non-operative treatment has shown favorable outcomes, while surgical interventions vary. Anatomical coracoclavicular reconstruction (ACCR) has demonstrated biomechanical advantages over traditional methods. Arthroscopic techniques offer advantages, minimizing deltoid detachment and allowing concurrent pathology identification. This study evaluates the outcomes of arthroscopic-assisted ACCR in chronic AC joint dislocation. Surgical Technique: Arthroscopic-assisted ACCR involves meticulous portal placement, tendon graft harvesting, diagnostic arthroscopy, and coracoid exposure. The clavicle tunnels were made to mimic the conoid and trapezoid ligament positions, using FibreTape#2 loop and Dog Bone Button for correct placement against the coracoid base, and passing the semitendinosus graft through to reconstruct the conoid ligament, reduction done and graft follow through for anatomical reconstruction. Methods: A retrospective cohort study at Hospital Kuala Lumpur analyzed 35 patients undergoing arthroscopic-assisted ACCR for Rockwood grade III - V AC joint dislocations. Inclusion criteria encompassed trauma ≥ 3 weeks prior, no prior shoulder injuries, and ≥12-month follow-up. Functional and radiological assessments utilized ASES scores and coracoclavicular distances, respectively. Statistical analysis employed descriptive statistics and logistic regression. Results: The mean age was 38.9 years (SD 11.26), and 34 of 35 patients were male. Grade IV injuries were predominant (37.1%). Waiting time for surgery averaged 234.9 days. Functional improvement was substantial postoperatively (ASES: 55.5 to 88.9). Radiological outcomes demonstrated reduced coracoclavicular distances and maintained reduction. No significant correlation was observed between injury grade and outcomes. Conclusion: Arthroscopic-assisted ACCR for chronic AC joint dislocation yields significant functional and radiological improvement, irrespective of injury grade. Waiting time for surgery exhibits minor impact on outcomes, emphasizing the procedure’s efficacy. Concomitant injuries do not impede success, highlighting the versatility of this approach in managing shoulder instability. The study contributes valuable insights into the nuanced management of chronic AC joint dislocations and supports the adoption of arthroscopic-assisted ACCR as a viable treatment option.

Catheter-Assisted Interlaminar Approach for Cervical Epidural Steroid Injection in Patient with Cervical Stenosis Caused by Ossification of Posterior Longitudinal Ligament: A Case Report

We present the case of a 64-year-old man with cervical ossification of the posterior longitudinal ligament (OPLL) experiencing chronic neck pain and radiculopathy for 6 months. A catheter-assisted interlaminar Cervical Epidural Steroid Injection (CESI) was performed under fluoroscopic guidance, targeting the affected C2-C6 levels. Significant improvement was observed after this procedure, with decreased pain scores (visual analogue scale (VAS) 8 to 2) and improved mobility. This technique not only enhances the effectiveness of CESI but also reduces the likelihood of complications such as stroke or epidural hematoma and thus provides an alternative treatment option for patients with multiple stenotic levels who are unsuitable for surgery or are unresponsive to conservative therapy such as medication or physical therapy.

Ultraviolet Source Assisted Enhancement of Attosecond Pulse

A promising method to improve the attosecond pulse intensity has been theoretically pre- sented by properly adding an ultraviolet pulse into the orthogonal two-color field. The results show that by properly adding a 125 nm ultraviolet pulse to the orthogonal two-color field, not only the harmonic yield is enhanced by 2 orders of magnitude compared with the original orthogonal two-color field case, but also the single short quantum path, which is selected to contribute to the harmonic spectrum, results in an ultrabroad 152 eV bandwidth. Moreover, by optimizing the laser parameters, we find that the harmonic enhancement is not very sen- sitive to the pulse duration and the polarized angle of the assisted ultraviolet pulse, which is much better for experimental realization. As a result, an isolated pulse with duration of 38 as can be obtained, which is 2 orders of magnitude improvement in comparison with the original two-color orthogonal field case.

KOH-assisted aqueous synthesis of bimetallic metal-organic frameworks and their derived selenide composites for efficient lithium storage

To solve low efficiency,environmental pollution,and toxicity for synthesizing zeolitic imidazolate frameworks(ZIFs)in organic solvents,a KOH-assisted aqueous strategy is proposed to synthesize bimetallic ZIFs polyhedrons,which are used as precursors to prepare bimetallic selenide and N-doped carbon(NC)composites.Among them,Fe–Co–Se/NC retains the three-dimensional(3D)polyhedrons with mesoporous structure,and Fe–Co–Se nanoparticles are uniform in size and evenly distributed.When assessed as anode material for lithium-ion batteries,Fe–Co–Se/NC achieves an excellent initial specific capacity of 1165.9 m Ah·g^(-1)at 1.0 A·g^(-1),and the reversible capacity of Fe–Co–Se/NC anode is 1247.4 m Ah·g^(-1)after 550 cycles.It is attributed to that the uniform composite of bimetallic selenides and N-doped carbon can effectively tune redox active sites,the stable 3D structure of Fe–Co–Se/NCs guarantees the structural stability and wettability of the electrolyte,and the uniform distribution of Fe–Co–S nanoparticles in size esuppresses the volume expansion and accelerates the electrochemical reaction kinetics.

Corneal astigmatic outcomes after femtosecond laser-assisted cataract surgery combined with surface penetrating arcuate keratotomies

AIM:To evaluate corneal astigmatic outcomes of femtosecond laser-assisted arcuate keratotomies(FAKs)combined with femtosecond-laser assisted cataract surgery(FLACS)over 12mo follow-up.METHODS:Totally 145 patients with bilateral cataracts and no ocular co-morbidities were recruited to a singlecentre,single-masked,prospective randomized controlled trial(RCT)comparing two monofocal hydrophobic acrylic intraocular lenses.Eyes with corneal astigmatism(CA)of>0.8 dioptres(D)received unpaired,unopened,surface penetrating FAKs at the time of FLACS.Visual acuity,subjective refraction and Scheimpflug tomography were recorded at 1,6,and 12mo.Alpins vectoral analyses were performed.RESULTS:Fifty-one patients(61 eyes),mean age 68.2±9.6y[standard deviation(SD)],received FAKs.Sixty eyes were available for analysis,except at 12mo when 59 attended.There were no complications due to FAKs.Mean pre-operative CA was 1.13±0.20 D.There was a reduction of astigmatism at all post-operative visits(residual CA 1mo:0.85±0.42 D,P=0.0001;6mo:0.86±0.35 D,P=0001;and 12mo:0.90±0.39,P=0.0001).Alpins indices remained stable over 12mo.Overall,the cohort was under-corrected at all time points.At 12mo,61%of eyes were within±15 degrees of pre-operative astigmatic meridian.CONCLUSION:Unpaired unopened penetrating FAKs combined with on-axis phacoemulsification are safe but minimally effective.CA is largely under-corrected in this cohort using an existing unmodified nomogram.The effect of arcuate keratotomies on CA remained stable over 12mo.

Comparative study of functional optical zone:small incision lenticule extraction versus femtosecond laser assisted excimer laser keratomileusis

AIM:To investigate the size of functional optical zone(FOZ)after small incision lenticule extraction(SMILE)versus femtosecond laser assisted excimer laser keratomileusis(FS-LASIK)for myopia correction and potential associated factors for FOZ.METHODS:A total of 133 patients who received corneal refractive surgery in our hospital between November 2018 and July 2021 were retrospectively enrolled.There were 63 patients(123 eyes)in SMILE group and 70patients(139 eyes)in FS-LASIK group.The size of FOZ was measured using Pentacam 3-dementional anterior segment analyzer before and 3mo after surgery,so as to analyze postoperative achieved functional optical zone(AFOZ)and its contributing parameters.RESULTS:When planned functional optical zone(PFOZ)was 6.5 mm for both groups,AFOZ was 1.45±0.27 and 1.67±0.25 mm smaller than preoperative FOZ in SMILE group and FS-LASIK group 3mo after surgery.AFOZ in SMILE group was significantly larger than that in FS-LASIK group(P<0.001).Variation of FOZ was negatively correlated with preoperative spherical equivalent(SE)and positively correlated with variation of mean keratometry value(△Km),variation of spherical aberration(△SA),and variation of Q-value(△Q,all P<0.001)in both groups.Multiple variable linear regression equations were△FOZ=1.354-0.1×pre-SE+0.336×△Q+1.462×△SA in SMILE group and△FOZ=1.512+0.137×△Q+0.468×△SA in FS-LASIK group.CONCLUSION:AFOZ is significantly smaller than preoperative FOZ in both SMILE and FS-LASIK groups.With the same PFOZ,larger AFOZ is achieved in SMILE group than in FS-LASIK group.

Adaptive Gain Tuning Rule for Nonlinear Sliding-mode Speed Control of Encoderless Three-phase Permanent Magnet Assisted Synchronous Motor

In this paper, an adaptive gain tuning rule is designed for the nonlinear sliding mode speed control(NSMSC) in order to enhance the dynamic performance and the robustness of the permanent magnet assisted synchronous reluctance motor(PMa-Syn RM) with considering the parameter uncertainties. A nonlinear sliding surface whose parameters are altering with time is designed at first. The proposed NSMSC can minimize the settling time without any overshoot via utilizing a low damping ratio at starting along with a high damping ratio as the output approaches the target set-point. In addition, it eliminates the problem of the singularity with the upper bound of an uncertain term that is hard to be measured practically as well as ensures a rapid convergence in finite time, through employing a simple adaptation law. Moreover, for enhancing the system efficiency throughout the constant torque region, the control system utilizes the maximum torque per ampere technique. The nonlinear sliding surface stability is assured via employing Lyapunov stability theory. Furthermore, a simple sliding mode estimator is employed for estimating the system uncertainties. The stability analysis and the experimental results indicate the effectiveness along with feasibility of the proposed speed estimation and the NSMSC approach for a 1.1-k W PMa-Syn RM under different speed references, electrical and mechanical parameters disparities, and load disturbance conditions.

240 nm AlGaN-based deep ultraviolet micro-LEDs:size effect versus edge effect

240 nm AlGaN-based micro-LEDs with different sizes are designed and fabricated.Then,the external quantum efficiency(EQE)and light extraction efficiency(LEE)are systematically investigated by comparing size and edge effects.Here,it is revealed that the peak optical output power increases by 81.83%with the size shrinking from 50.0 to 25.0μm.Thereinto,the LEE increases by 26.21%and the LEE enhancement mainly comes from the sidewall light extraction.Most notably,transversemagnetic(TM)mode light intensifies faster as the size shrinks due to the tilted mesa side-wall and Al reflector design.However,when it turns to 12.5μm sized micro-LEDs,the output power is lower than 25.0μm sized ones.The underlying mechanism is that even though protected by SiO2 passivation,the edge effect which leads to current leakage and Shockley-Read-Hall(SRH)recombination deteriorates rapidly with the size further shrinking.Moreover,the ratio of the p-contact area to mesa area is much lower,which deteriorates the p-type current spreading at the mesa edge.These findings show a role of thumb for the design of high efficiency micro-LEDs with wavelength below 250 nm,which will pave the way for wide applications of deep ultraviolet(DUV)micro-LEDs.

Ultraviolet‑Irradiated All‑Organic Nanocomposites with Polymer Dots for High‑Temperature Capacitive Energy Storage

Polymer dielectrics capable of operating efficiently at high electric fields and elevated temperatures are urgently demanded by next-generation electronics and electrical power systems.While inorganic fillers have been extensively utilized to improved high-temperature capacitive performance of dielectric polymers,the presence of thermodynamically incompatible organic and inorganic components may lead to concern about the long-term stability and also complicate film processing.Herein,zero-dimensional polymer dots with high electron affinity are introduced into photoactive allyl-containing poly(aryl ether sulfone)to form the all-organic polymer composites for hightemperature capacitive energy storage.Upon ultraviolet irradiation,the crosslinked polymer composites with polymer dots are efficient in suppressing electrical conduction at high electric fields and elevated temperatures,which significantly reduces the high-field energy loss of the composites at 200℃.Accordingly,the ultraviolet-irradiated composite film exhibits a discharged energy density of 4.2 J cm^(−3)at 200℃.Along with outstanding cyclic stability of capacitive performance at 200℃,this work provides a promising class of dielectric materials for robust high-performance all-organic dielectric nanocomposites.

Spectra-assisted laser focusing in quantitative analysis of laser-induced breakdown spectroscopy for copper alloys

Laser-induced breakdown spectroscopy(LIBS)is a capable technique for elementary analysis,while LIBS quantitation is still under development.In quantitation,precise laser focusing plays an important role because it ensures the distance between the laser and samples.In the present work,we employed spectral intensity as a direct way to assist laser focusing in LIBS quantitation for copper alloys.It is found that both the air emission and the copper line could be used to determine the position of the sample surface by referencing the intensity maximum.Nevertheless,the fine quantitation was only realized at the position where the air emission(e.g.O(I)777.4 nm)reached intensity maximum,and also in this way,a repeatable quantitation was successfully achieved even after 120 days.The results suggested that the LIBS quantitation was highly dependent on the focusing position of the laser,and spectra-assisted focusing could be a simple way to find the identical condition for different samples’detection.In the future,this method might be applicable in field measurements for LIBS analysis of solids.