Excellent Long-term Performance Research Articles

High interfacial storage capability of porous NiMn2O4/C hierarchical tremella-like nanostructures as the lithium ion battery anode.

Porous hierarchical NiMn2O4/C tremella-like nanostructures are obtained through a simple solvothermal and calcination method. As the anode of lithium ion batteries (LIBs), porous NiMn2O4/C nanostructures exhibit a superior specific capacity and an excellent long-term cycling performance even at a high current density. The discharge capacity can stabilize at 2130 mA h g(-1) within 350 cycles at a current density of 1000 mA g(-1). After a long-term cycling of 1500 cycles, the capacity is still as high as 1773 mA h g(-1) at a high current density of 4000 mA g(-1), which is almost five times higher than the theoretical capacity of graphite. The porous NiMn2O4/C hierarchical nanostructure provides sufficient contact with the electrolyte and fast three-dimensional Li(+) diffusion channels, and dramatically improves the capacity of NiMn2O4/C via interfacial storage.

Active pump-seed-pulse synchronization for OPCPA with sub-2-fs residual timing jitter.

Short-pulse-pumped optical parametric chirped pulse amplification (OPCPA) requires a precise temporal overlap of the interacting pulses in the nonlinear crystal to achieve stable performance. We present active synchronization of the ps-pump pulses and the broadband seed pulses used in an OPCPA system with a residual timing jitter below 2 fs. This unprecedented stability was achieved utilizing optical parametric amplification to generate the error signal, requiring less than 4 pJ of seed- and 10 µJ of pump-pulse-energy in the optical setup. The synchronization system shows excellent long-term performance and can be easily implemented in almost any OPCPA system.

Epicardial leads in adult cardiac resynchronization therapy recipients: a study on lead performance, durability, and safety.

Transvenous left ventricular (LV) lead placement for cardiac resynchronization therapy-defibrillator (CRT-D) delivery is unsuccessful in 8% to 10% of cases. These patients might benefit from an epicardial lead. However, data on long-term epicardial lead performance are scarce. Furthermore, extracting an epicardial lead requires a rethoracotomy. The purpose of this study was to determine data on almost a decade of experience with epicardial leads and investigate the safety of partially leaving this lead in place after device infection. All adult patients receiving an epicardial lead (Medtronic CapSure Epi, model 4968) for CRT-D in the Leiden University Medical Center were included. Leads were implanted during a standalone procedure or in combination with other cardiothoracic procedures. Electrical lead parameters were assessed at implantation and every 6 months thereafter. In case of device infection the epicardial lead was cut off parasternal, just outside the thoracic cavity, leaving the distal part of the lead in place. Two-hundred sixteen patients were included with a median follow-up of 3 years (25th-75th percentile 1.0-5.5). LV pacing threshold decreased within 6 months after implantation [1.1 V (95% confidence interval [CI] 0.9-1.2) vs 0.8 V (95% CI 0.7-0.9), P = .01] and stabilized thereafter. Mean LV electrogram was 15.2 ± 7.5 mV, and average lead impedance was 633.5 ± 174.0 Ω. Five-year cumulative incidence was 1.6% for lead failure and 9.6% for device infection. The retained epicardial lead caused skin erosion in 3 patients and fistula formation in 1. This study demonstrates that epicardial LV leads have an excellent long-term performance. Partially retaining the lead after device infection was associated with a risk of reinfection with limited long-term clinical implications for the patient.

Nanostructured Li3V2(PO4)3/C composite as high-rate and long-life cathode material for lithium ion batteries

Nanostructured Li3V2(PO4)3/C composite has been synthesized by a facile microemulsion method. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectra, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results confirm that the as-prepared Li3V2(PO4)3/C sample shows the pure monoclinic structure and nanosphere morphology. Li3V2(PO4)3/C has a particle size of about 100nm, and these nanoparticles are connected each other by the conductive carbon network. Electrochemical measurements demonstratethat the Li3V2(PO4)3/C nanoparticles can deliver discharge capacities of 129.8, 126.1, 118.0, 116.1 and 110.1 mAh g−1 between 3.0 and 4.3V, and 171.4, 163.1, 153.2, 144.0 and 133.4 mAh g−1 between 3.0 and 4.8V at 1, 2, 5, 10 and 20C, respectively. Even at 20C rate, it still can present a reversible discharge capacity of 101.8 mAh g−1 with 92.5% capacity retention after 1400 cycles and 96.4 mAh g−1 with 72.3% capacity retention after 1000 cycles in the potential ranges of 3.0-4.3V and 3.0-4.8V, respectively. The excellent rate capability and long-term cycle performance demonstrate that the Li3V2(PO4)3/C nanoparticles prepared in this work has great potential for application as cathode materials in high-power lithium ion batteries.

High temperature nano-coated electric-arc-induced long-period gratings working at the dispersion turning point for refractive index sensing

In this paper we present for the first time electric-arc-induced long-period gratings (LPGs) working at the dispersion turning point (DTP) in the wavelength range of about 1550 nm. The DTP is achieved by reducing the grating period down to about 190 µm. In contrast to LPGs fabricated with the typical UV laser-based method, arc-induced gratings show high thermal stability and excellent long-term performance. These advantages make it possible to coat the LPGs using thin-film deposition methods, which require high temperatures. We present the effect of thin silicon nitride (SiNx) overlay deposited by the radio-frequency plasma-enhanced chemical vapor deposition (RF PECVD) method. This technique increased the refractive index sensitivity of the LPGs from 400–700 nm/refractive index unit (RIU) to 887–2146 nm/RIU.

Application of biological island grids in wastewater treatment and its microbial mechanisms

Biological island grid system (BIGS) is a new type of biological floating island which allows for larger bacterial population to grow in the system. In this study, the nutrient-removal efficiencies of two different BIGS, constructed with Oenanthe javanica and Iris pseudacorus were investigated. Molecular technique was used to study the microbial mechanisms of pollutants removal. Results showed that BIGS had an excellent long-term removal performance compared with conventional biological floating island. The NH4+-N-removal efficiencies of BIGS were 89.5 and 91.2%, which were 16.3 and 16.9% higher than the control, respectively. Over 75% of chemical oxygen demand (COD) was removed in both BIGS while the COD-removal efficiencies were only 71.4 and 69.1% in the control. Analysis of DGGE pattern showed that the diversity index of the elastic space in BIGS was 1.93–2.65. Furthermore, month played a main role in microbial community structures. About 46.2% of the micro-organisms in the system belonged to Proteobacteria, followed by uncultured bacteria. There were lots of nitrogen-fixing and nitrate-degradation bacteria among them, which might play an important role in the nitrogen removal from the polluted water. The present study proved that BIGS was an effective approach to improve water quality.

Supercritical Carbon Dioxide Assisted Deposition of Fe3O4Nanoparticles on Hierarchical Porous Carbon and Their Lithium-Storage Performance

A composite of highly dispersed Fe3 O4 nanoparticles (NPs) anchored in three-dimensional hierarchical porous carbon networks (Fe3 O4 /3DHPC) as an anode material for lithium-ion batteries (LIBs) was prepared by means of a deposition technique assisted by a supercritical carbon dioxide (scCO2 )-expanded ethanol solution. The as-synthesized Fe3 O4 /3DHPC composite exhibits a bimodal porous 3D architecture with mutually connected 3.7 nm mesopores defined in the macroporous wall on which a layer of small and uniform Fe3 O4 NPs was closely coated. As an anode material for LIBs, the Fe3 O4 /3DHPC composite with 79 wt % Fe3 O4 (Fe3 O4 /3DHPC-79) delivered a high reversible capacity of 1462 mA h g(-1) after 100 cycles at a current density of 100 mA g(-1) , and maintained good high-rate performance (728, 507, and 239 mA h g(-1) at 1, 2, and 5 C, respectively). Moreover, it showed excellent long-term cycling performance at high current densities, 1 and 2 A g(-1) . The enhanced lithium-storage behavior can be attributed to the synergistic effect of the porous support and the homogeneous Fe3 O4 NPs. More importantly, this straightforward, highly efficient, and green synthetic route will definitely enrich the methodologies for the fabrication of carbon-based transition-metal oxide composites, and provide great potential materials for additional applications in supercapacitors, sensors, and catalyses.

Are there universal restorative composites for anterior and posterior teeth?

ObjectiveThis retrospective, longitudinal clinical study investigated the longevity up to 20 years of posterior restorations placed with 3 universal composites (Charisma, Herculite XR, Z100) and of anterior restorations placed with 2 universal composites (Charisma, Herculite XR). MethodsRecords from 90 patients were retrieved from a private practice (374 posterior, 219 anterior restorations). Clinical evaluation was performed by the FDI criteria. Survival analysis was assessed using Kaplan–Meier method and Log-Rank test, and factors associated with failure by multivariate Cox regression with shared frailty. ResultsIn the first 10 years, almost 95% of the restorations were satisfactory, showing increased failure thereafter. Charisma showed the most failures in anterior and posterior areas. Annual failure rates varied between 0.3% and 2.5%, with slightly better performance for anterior restorations. Fracture (posterior) and aesthetics (anterior) were the main reasons for failure. Clinical significanceDifferences were observed between restorative materials with different properties, but these became apparent only after more than 10 years of clinical service. The present study provides evidence that in a patient group with low caries risk, anterior and posterior restorations placed with universal composites may have excellent long-term clinical performance.

노후 콘크리트 포장 절삭 덧씌우기의 침투수에 의한 파손 최소화 방안 연구

PURPOSES: The purpose of this study was to investigate the disintegration mechanism of concrete due to the infiltration of the moisture to the milling overlay pavement and to come up with a method to minimize the disintegration as well as verifying the effectiveness of the edge sealing and Fogseal method. METHODS : This study investigated the distress mechanism due to the infiltrated moisture remaining in the milling overlay pavement through chloride freezing test and verified the effectiveness of the sealing of the milling edge and fog seal methods, which have been devised to minimize the moisture infiltration, through laboratory water permeability test. Additionally, long-term pavement performance was compared for the effectiveness of the proposed method through under loading test, and field water permeability test was carried out to verify the field applicability of the proposed method. RESULTS: The result of the research confirmed that chloride deteriorates the concrete surface through disintegration and lowers its strength and that the laboratory moisture infiltration test verified the effectiveness of the milling edge sealing and fog seal methods in the deterrence of moisture infiltration to the overlay pavement with excellent long-term performance of the pavement treated with the proposed method. Although the field water permeability test revealed some deterrence of moisture infiltration of the milling edge sealing and fog seal methods to a certain extent, the difference was a little. CONCLUSIONS: The milling edge sealing and fog seal methods are limited in their effectiveness for the cases of improvident compaction management or mixture with large void, and it is believed that installation of subsurface drainage is more effective in these cases.

Facile synthesis of hierarchical mesoporous Li4Ti5O12 microspheres in supercritical methanol

A facile, template-free route using supercritical methanol for the preparation of hierarchical mesoporous Li4Ti5O12 spinel microspheres in a very short reaction time is introduced. Nanosized, primary Li4Ti5O12 particles (5–10 nm) are loosely aggregated and form micron-sized, secondary mesoporous spheres (0.2–2.0 μm) with a pore size of 2–10 nm. Subsequent calcination of the as-synthesized Li4Ti5O12 at a low temperature of 600 °C results in excellent long-term cyclability and high rate performance. The discharge capacity after 400 cycles at 1 C is 134.9 mAh g−1 (77.6% of the initial discharge capacity), and the discharge capacity at 10 C is 108.5 mAh g−1. The formation mechanism of hierarchical mesoporous microspheres in supercritical methanol is discussed.

Ordered mesoporous TiO2–C nanocomposite as an anode material for long-term performance lithium-ion batteries

A nanocomposite of ordered mesoporous pure anatase TiO2–C was successfully synthesized for the first time by using ordered mesoporous carbon as a nano-reactor and exhibited a short-range ordered mesoporous structure. It was found that carbon was coated on the surface of TiO2 nanoparticles to form a thin layer. Using this material as an anode in rechargeable lithium-ion batteries, it displayed a large reversible capacity, high rate performance and excellent long-term cycling stability. For instance, a large reversible capacity of 166 mA h g−1 and an average Coulombic efficiency of 99.7% could be maintained even after 900 cycles at a current rate of 1 C. This can be attributed to the structure of the ordered mesoporous TiO2–C nanocomposite. Such a nanostructure provides both electron and lithium-ion pathways which are essential for rechargeable lithium-ion batteries with a large capacity and excellent long-term performance.

Stentless root bioprosthesis for repair of acute type A aortic dissection

The superior hemodynamics and excellent long-term clinical performance of stentless xenografts are well described. However, the early and midterm clinical outcomes of stentless valves in patients with acute type A dissection are widely unknown. The current study evaluated the early and midterm clinical outcomes of stentless bioprosthesis for repair of acute type A aortic dissection. Between May 2005 and December 2009, 24 of 80 patients underwent root replacement using the Medtronic Freestyle xenograft (Medtronic Inc, Minneapolis, Minn) at the Meijer Heart Center. Prospective data collection was used for retrospective review. Univariate comparisons of preoperative, intraoperative, and postoperative variables were performed between patients who underwent stentless root bioprosthesis for the correction of acute type A aortic dissection (n=24). The mean age of patients was 57 years, with 15 patients aged less than 65 years. Axillary and femoral artery cannulation were used in 16 patients (67%) and 7 patients (29%), respectively. Median crossclamp and cardiopulmonary bypass times were 198 minutes (92-480 minutes) and 288 minutes (109-588 minutes), respectively. Median circulatory arrest time was 28 minutes (24-50 minutes). Operative mortality rate was 25%. Actuarial 5-year survival was 62.5%. No patients required redo aortic root replacement. Stentless valve implantation can be accomplished with satisfactory early and midterm clinicaloutcomes and is a valuable option in patients with acute aortic dissection who require root replacement.

Short- and long-term leakage through composite liners. The 7th Arthur Casagrande Lecture1This lecture was presented at the 14th Pan-American Conference on Soil Mechanics and Geotechnical Engineering, Toronto, Ont., October 2011, and a pre-print appeared in the conference proceedings.

The factors that may affect short-term leakage through composite liners are examined. It is shown that the leakage through composite liners is only a very small fraction of that expected for either a geomembrane (GM) or clay liner (CL) alone. However, the calculated leakage through holes in a GM in direct contact with a clay liner is typically substantially smaller than that actually observed in the field. It is shown that calculated leakage taking account of typical connected wrinkle lengths observed in the field explains the observed field leakage through composite liners. Provided that care is taken to avoid excessive connected wrinkle lengths, the leakage through composite liners is very small compared to a typical GM or CL alone. It is shown that the leakage through composite liners with a geosynthetic clay liner (GCL) is typically much less than for composite liners with a compacted clay liner (CCL). Finally, factors that will affect long-term leakage through composite liners are discussed. It is concluded that composite liners have performed extremely well in field applications for a couple of decades and that recent research both helps understand why they have worked so well and provides new insight into issues that need to be considered to ensure excellent long-term liner performance of composite liners — especially for applications where the liner temperature can exceed about 35 °C.

Research on Special Cement for the Concrete with Ultra-Fine Iron Tailings

This essay is the subject of national eleventh five support schemes: The analysis of key technology on emission reduction and comprehension utilization of solid waste from large iron ore mine (Number:2008BAB32B14).For the concrete with ultra-fine iron tailings the research on the new special cement has been successfully prepared by means of using a low dosage of crystal-core-element named CCE for short (which has an excellent capability to accelerate the hydration speed and develop the strength of the cement)and high percentage of blast furnace slag and other several industrial residue. Compared to the ordinary Portland cement grade 42.5, the new cement has several outstanding virtues such as lower use level of cement clinker, higher level usage of industrial residue and lower cost. According to the cement standard GB175-2007, strength of special cement sample NO.3 is same as the ordinary Portland cement grade 42.5 with the standard sand. When with ultra-fine iron tailings, the new special cement has higher strength after 28days than the OPC. That shows the special cement has an excellent long-term performance of concretion. The manufacturing cost of the new special cement sample NO.3 is decreased by 20.76% than the ordinary Portland cement grade 42.5, that will bring a great environment and economic effect.

Can Soy Methyl Esters Improve Concrete Pavement Joint Durability?

Although many concrete pavements provide excellent long-term performance, some pavements (primarily in the Midwest) have shown premature deterioration at the joints. This premature deterioration is a concern because such deterioration can shorten the life of pavements that are otherwise functioning well. Previous work has hypothesized that these joints may be susceptible to preferential fluid saturation, which can lead to freeze–thaw damage or chemical degradation. This work examines the use of soy methyl ester–polystyrene (SME-PS) blends as a method to reduce the rate of fluid ingress into the pore system of the concrete and thereby make the concrete more resistant to deterioration. SME-PS is derived from soybeans and has demonstrated an ability to reduce fluid absorption in concrete when used as a topical treatment. A series of experiments was developed to evaluate the effectiveness of various dosage rates of SME-PS for increasing concrete durability at pavement joints. The experiments show that SME-PS reduces fluid ingress, salt ingress, and the potential for freeze–thaw damage. As a result of the positive experimental results, the Indiana Department of Transportation is conducting field trials that use SME-PS on concrete pavements that are beginning to show signs of premature deterioration with the expectation that SME-PS will extend the life of the joints and thereby reduce maintenance cost and extend the life of concrete pavements.

Preliminary Performance Assessment for Deep Borehole Disposal of High-Level Radioactive Waste

ABSTRACTDeep boreholes have been proposed for many decades as an option for permanent disposal of high-level radioactive waste and spent nuclear fuel. Disposal concepts are straightforward, and generally call for drilling boreholes to a depth of four to five kilometers (or more) into crystalline basement rocks. Waste is placed in the lower portion of the hole, and the upper several kilometers of the hole are sealed to provide effective isolation from the biosphere. The potential for excellent long-term performance has been recognized in many previous studies. This paper reports updated results of what is believed to be the first quantitative analysis of releases from a hypothetical disposal borehole repository using the same performance assessment methodology applied to mined geologic repositories for high-level radioactive waste. Analyses begin with a preliminary consideration of a comprehensive list of potentially relevant features, events, and processes (FEPs) and the identification of those FEPs that appear to be most likely to affect long-term performance in deep boreholes. The release pathway selected for preliminary performance assessment modeling is thermally-driven flow and radionuclide transport upwards from the emplacement zone through the borehole seals or the surrounding annulus of disturbed rock. Estimated radionuclide releases from deep borehole disposal of spent nuclear fuel, and the annual radiation doses to hypothetical future humans associated with those releases, are extremely small, indicating that deep boreholes may be a viable alternative to mined repositories for disposal of both high-level radioactive waste and spent nuclear fuel.

Endurance and Performance of Two Different Concepts for Left Ventricular Stimulation with Bipolar Epicardial Leads in Long-Term Follow-Up

Epicardial left ventricular (LV) leads represent an alternative for CRT therapy if transvenous lead implantation fails. Data on endurance, performance, the impact of the surgical approach (lateral minithoracotomy vs. median sternotomy simultaneously with other cardiac surgery), and the optimal technical concept (screw-in vs. suture-on) is limited. Over a period of 48 months we evaluated 130 consecutive patients with comparable characteristics. A total of 54 screw-in (MyoDex™ 1084T, SJM) and 76 suture-on (Capture Epi 4968, Medtronic) bipolar epicardial steroid-eluting LV leads were implanted either via a left lateral or a median thoracotomy. Sensing, pacing threshold, impedance and NYHA class were recorded at defined time points. No surgery-related death or major complication was observed. At the time of implantation, the pacing threshold, sensing and NYHA class did not differ significantly between the two groups. The impedances of screw-in leads were significantly lower compared to those of suture-on leads. Suture-on leads showed a moderate initial drop in their pacing threshold but afterwards remained stable. Screw-in leads were characterized by a moderate but significant increase in the pacing threshold in the first year followed by a continuous decrease thereafter. Twenty-four months post-implantation no differences between both lead types could be detected. Sensing and NYHA class improved in both groups. The surgical approach had no significant impact on lead functionality. Our study showed that the implantation of epicardial leads was safe with very low complication rates. There was no superior technical epicardial lead concept (screw-in vs. suture-on leads) and all epicardial leads demonstrated an excellent long-term performance and durability. Therefore, it seems that epicardial leads represent a good alternative to transvenous leads and surgeons should be encouraged to implant epicardial leads during concomitant cardiac surgery when the indications for CRT are present.

Genetic characteristics in children with cochlear implants and the corresponding auditory performance

To explore the genetic characteristics of children with cochlear implants (CIs) and to correlate the auditory performance after implantation to the genetic diagnosis of children with CIs. Prospective cohort study. Mutations of four common deafness-associated genes, GJB2, SLC26A4, the mitochondrial 12S rRNA gene, and OTOF, were screened in 743 unrelated children with idiopathic sensorineural hearing impairment, including 180 and 563 children with and without CIs, respectively. The allele frequencies and audiologic features were compared between both groups. The Categories of Auditory Performance (CAP) scores at 3 years after implantation were then analyzed according to the genotypes. A definitive genetic diagnosis was made in 37 (20.6%) of the 180 CI children. A significant difference in allele frequencies between CI and non-CI children was found in GJB2 mutations (chi-square test, P < .01), but not in SLC26A4 mutations, mitochondrial 12S rRNA mutations, or OTOF mutations (all P > .05). Further analysis revealed that the difference might have resulted from distinct audiological features in each group. Among the 110 CI children who had received more than 3 years of rehabilitation after implantation, the 35 children with mutations had better CAP scores than the 75 children without mutations. A significant prevalence of genetic mutations was identified in children with CIs, suggesting the need for routine genetic assessments. The frequencies of common deafness-associated mutations were different between children with and without CIs. The presence of genetic mutations was associated with an excellent long-term auditory performance outcome after implantation.

Experimental investigation of installation damage for geogrids

Installation damage tests were performed to evaluate both damaged and undamaged geosynthetics specimens. Accelerated creep tests at 20, 35 and 50°C were performed at various loading levels to determine the maximum short-term strength of the geosynthetic reinforcements. The long-term performance of drawn-type, warp/knitted-type and junction bonded-type membranes, composite-type geogrid, and strip-type geosynthetic reinforcement was calculated from the reduction factors. The total factor of safety for the geosynthetic reinforcements was calculated from the experimental results of these reduction factors and the long-term design strength of the geosynthetic reinforcements was also calculated. The reduction factor due to creep deformation was found to affect the long-term performance. Among the geosynthetic reinforcements studied, the strip-type reinforcements and composite-type geogrids showed excellent long-term performance.

The fate of Hancock II porcine valve recipients 25 years after implant☆

The Hancock II (HII) is a second-generation porcine bioprosthesis introduced into clinical use in 1982. This study aimed to evaluate very long-term outcomes for the HII valve in a large patient population. Between May 1983 and November 1993, 517 consecutive patients (pts) (309 male, mean age: 64+/-9 years) underwent valve replacement (VR) surgery with HII, with 302 (58.4%) in the aortic VR (AVR) and 215 (41.6%) in the mitral VR (MVR) position, respectively. At implant, 106 pts (20.5%) were <60 years of age (G1), while 411 (79.5%) were > or =60 years of age (G2). The 25-year follow-up was complete for all pts at a median of 12 years (range: 0-25). Long-term death occurred in 208 AVR and in 165 MVR pts. Survival at 15 and 20 years was 39.5% and 23.3% in AVR pts and 39.0% and 15.8% in MVR pts. At 25 years the survival of MVR pts was 13.7% (four pts at risk). Late freedom from re-operation was 85.5% and 79.3% at 15 and 20 years in the AVR pts and 73.3% and 52.8% in the MVR pts, respectively. In the AVR population, 20-year freedom from re-operation was 52.2% in G1 pts and 86.8% in G2 pts (p<0.0001), while in the MVR population it was 41.4% in G1 pts and 61.9% in G2 pts (p=0.201), respectively. These results confirm the excellent long-term performance of the HII bioprosthesis.