Effects of Cu-Wire Surface Fluctuations on Early Failures

Different chemical mechanical polishing （CMP） slurries are used to obtain single-damascene Cu-wires with different surface fluctuations as well as pre-existing surface-defects in wires with rougher surfaces. The presence of such pre-existing defects strongly increases the rate of early failures to almost 100%, reduces electromigration lifetime rapidly to the level of early failures, and changes the multimodal failure distribution into monomodal. The activation energy （0. 74±0.02eV） for the failure mechanism associated with these pre-existing defects confirms a dominant surface diffusion. It shows how a weakest link approximation analysis can he applied to a single wire by dividing the wire into relevant segments and assigning different failure mechanisms to the various segments. The analysis confirms that, although surface-defects are not the fastest early failure mechanism, the ten times higher surface-defectdensity in the rougher wires is responsible for the observed high early-failure rate and unreliable performance.

Validation and performance of three scoring systems for predicting primary non-function and early allograft failure after liver transplantation

Background: Primary non-function(PNF) and early allograft failure(EAF) after liver transplantation(LT) seriously affect patient outcomes. In clinical practice, effective prognostic tools for early identifying recipients at high risk of PNF and EAF were urgently needed. Recently, the Model for Early Allograft Function(MEAF), PNF score by King's College(King-PNF) and Balance-and-Risk-Lactate(BAR-Lac) score were developed to assess the risks of PNF and EAF. This study aimed to externally validate and compare the prognostic performance of these three scores for predicting PNF and EAF. Methods: A retrospective study included 720 patients with primary LT between January 2015 and December 2020. MEAF, King-PNF and BAR-Lac scores were compared using receiver operating characteristic(ROC) and the net reclassification improvement(NRI) and integrated discrimination improvement(IDI) analyses. Results: Of all 720 patients, 28(3.9%) developed PNF and 67(9.3%) developed EAF in 3 months. The overall early allograft dysfunction(EAD) rate was 39.0%. The 3-month patient mortality was 8.6% while 1-year graft-failure-free survival was 89.2%. The median MEAF, King-PNF and BAR-Lac scores were 5.0(3.5–6.3),-2.1(-2.6 to-1.2), and 5.0(2.0–11.0), respectively. For predicting PNF, MEAF and King-PNF scores had excellent area under curves(AUCs) of 0.872 and 0.891, superior to BAR-Lac(AUC = 0.830). The NRI and IDI analyses confirmed that King-PNF score had the best performance in predicting PNF while MEAF served as a better predictor of EAD. The EAF risk curve and 1-year graft-failure-free survival curve showed that King-PNF was superior to MEAF and BAR-Lac scores for stratifying the risk of EAF. Conclusions: MEAF, King-PNF and BAR-Lac were validated as practical and effective risk assessment tools of PNF. King-PNF score outperformed MEAF and BAR-Lac in predicting PNF and EAF within 6 months. BAR-Lac score had a huge advantage in the prediction for PNF without post-transplant variables. Proper use of these scores will help early identify PNF, standardize grading of EAF and reasonably select clinical endpoints in relative studies.

Early renal failure as a cardiovascular disease:Focus on lipoprotein(a) and prothrombotic state

Patients with renal failure are at increased risk of cardiovascular events even at the earliest stages of disease. In addition to many classic cardiovascular risk factors, many conditions that are commonly identified as emerging risk factors might contribute to occurrence of cardiovascular disease. Changes in circulating levels of many of these emerging risk factors have been demonstrated in patients with early stages of renal failure caused by different types of renal disease and have been associated with detection of cardiovascular complications. However, for most of these factors evidence of benefts of correction on cardiovascular outcome is missing. In this article, we comment on the role of lipoprotein（a） and prothrombotic factors as potential contributors to cardiovascular events in patients with early renal failure.

L-GrAFT_(7) has High Accuracy in Predicting Early Allograft Failure after Liver Transplantation: A Multicenter Cohort Study in China

Background and Aims:Increasing utilization of extended criteria donor leads to an increasing rate of early allograft failure after liver transplantation.However,consensus of definition of early allograft failure is lacking.Methods:A retrospective,multicenter study was performed to validate the Liver Graft Assessment Following Transplantation(L-GrAFT)risk model in a Chinese cohort of 942 adult patients undergoing primary liver transplantation at three Chinese centers.L-GrAFT(L-GrAFT7 and L-GrAFT10)was compared with existing models:the Early Allograft Failure Simplified Estimation(EASE)score,the model of early allograft function(MEAF),and the Early Allograft Dysfunction(EAD)model.Univariate and multivariate logistic regression were used to find risk factors of L-GrAFT high-risk group.Results:L-GrAFT7 had an area under the curve of 0.85 in predicting 90-day graft survival,significantly superior to MEAF[area under the curve(AUC=0.78,p=0.044)]and EAD(AUC=0.78,p=0.006),while there was no statistical significance between the predicting abilities of L-GrAFT7 and EASE(AUC=0.84,p>0.05).Furthermore,L-GrAFT7 maintains good predicting ability in the subgroup of high-donor risk index(DRI)cases(AUC=0.83 vs.MEAF,p=0.007 vs.EAD,p=0.014)and recipients of donors after cardiac death(AUC=0.92 vs.EAD,p<0.001).Through multivariate analysis,pretransplant bilirubin level,units of packed red blood cells,and the DRI score were selected as independent risk factors of a L-GrAFT7 high-risk group.Conclusions:The accuracy of L-GrAFT7 in predicting early allograft failure was validated in a Chinese multicenter cohort,indicating that it has the potential to become an accurate endpoint of clinical practice and transitional study of machine perfusion.

Influence of Lubrication Performance on the Service Life of Rolling Mill Bearings

In order to confirm the early failure cause of a four-row cylindrical roller bearing at the backup roll position of a six-high cold sheet mill, its lubrication behavior under harsh operating conditions is investigated. Through establishing and solving the Elastohydrodynamic Lubrication （EHL） model of the roller-inner raceway contact region, the minimum oil film thickness and the real lubrication performance are achieved. The results show the bearing failures come from the poor oil film thickness in the case of high temperature and low rotational speed, which leads to contact wear. So various approaches to improve bearing life via improving lubrication are compared. It has been proved decreasing surface roughness of both contact bodies is an effective way.

Reconstruction of Probability Density Function for Gamma Distribution

The probability distributions of small sample data are difficult to determine,while a large proportion of samples occur in the early failure period,so it is particularly important to make full use of these data in the statistical analysis.Based on gamma distribution,four methods of probability density function(PDF)reconstruction with early failure data are proposed,and then the mean time between failures(MTBF)evaluation expressions are concluded from the reconstructed PDFs.Both theory analysis and an example show that method 2 is the best evaluation method in dealing with early-failure-small-sample data.The reconstruction methods of PDF also have certain guiding significance for other distribution types.

Early graft failure after meniscus allograft transplantation： an unusual cause of using all-inside meniscal repair device

Meniscal allograft transplantation （MAT） may offer .an attractive alternative to restore the normal biomechanical structure of knees. The mean early failure rate （≤2 years） of MAT is approximately 10%.1-3 A successful outcome of MAT depends on the ligamentous stability of knee, limb alignment, graft types, and graft fixation methodsY Graft fixations include the meniscal horns and the peripheral rim. Techniques for fixation of the peripheral rim include sutures or a meniscal repair device such as FasT-Fix （Smith ＆ Nephew Inc, Andover, MA, USA）. Here we present an unusual case of early graft failure using FasT-Fix sutured to the peripheral rim of the graft.

TDDB improvement by optimized processes on metal-insulator-silicon capacitors with atomic layer deposition of Al_2O_3 and multi layers of TiN film structure

A metal-insulator-silicon （MIS） capacitor with hemi-spherical grained poly atomic layer deposition （ALD） deposited Al2O3 and multi-layered chemical vapor deposition （CVD） TiN structure is fabricated. The impact of the deposition process and post treatment condition on the MIS capacitor＇s time-dependent dielectric breakdown （TDDB） performance is also studied. With an optimized process, it is confirmed by Auger electron spectroscopy and secondary ion mass spectrometry analysis that the Al（CH3）3/O3-based ALD Al2O3 dielectric film is carbon free and the hydrogen content is as low as 9 × 1019 cm-3. The top electrode TiN is obtained by multi-layered TiCl4/NH3 CVD deposited TiN followed by 120 s post NH3 treatment after each layer. This has higher diffusion barrier in preventing impurity diffusion through TiN into the Al2O3 dielectric due to its smaller grain size. As shown in energy dispersive X-ray analysis, there is no chlorine residue in the MIS capacitor structure. The leakage current of the capacitor is lower than 1 × 10-12 A/cm2. No early failures under stress conditions are found in its TDDB test. The novel MIS capacitor is proven to have excellent reliability for advanced DRAM technology.