CircRNA SCAR Improves High-Glucose-Induced Mitochondrial Dysfunction and Permeability Damage in Retinal Microvascular Endothelial Cells.

This study was designed to assess the role and mechanism of circRNA SCAR in human retinal microvascular endothelial cells (hRMVECs) treated with high glucose. Quantitative real-time polymerase chain reaction (qRT-PCR) and cell counting kit 8 (CCK-8) were used to detect the effects of different concentrations of glucose on circRNA SCAR expression and cell proliferation in hRMVECs. Cell viability, levels of oxygen species (ROS), malondialdehyde (MDA) and adenosine triphosphate (ATP), as well as activities of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) in the transfected hRMVECs in each group were detected using CCK-8 and their corresponding detection kits. Changes in mtDNA copy number in high-glucose-induced hRMVECs were observed by qRT-PCR. Additionally, western blot was applied to detect effect of overexpressing circRNA SCAR on the expression levels of mitochondrial function-related proteins (Drp1 and Fis1) and cell permeability-related proteins (claudin-5, occludin and ZO-1) in hRMVECs under high-glucose concentration. According to experimental results, high glucose significantly downregulated circRNA SCAR expression and inhibited cell proliferation in hRMVECs. Instead, overexpression of this circRNA SCAR promoted cell proliferation, reduced levels of ROS, MDA and ATP, and increased SOD and CAT activities in hRMVECs under high-glucose concentration. Also, circRNA SCAR overexpression reversed the high-glucose-induced decrease in mtDNA copy number as well as, high-glucose-induced upregulation of Drp1 and Fis1 protein expression and downregulation of claudin-5, occludin and ZO-1 protein expression in hRMVECs. In summary, circRNA SCAR promotes the proliferation of hRMVECs under high-glucose concentration, alleviates oxidative stress induced by high glucose, and improves mitochondrial function and permeability damage.

Critical behaviors of nonlinear contagion models with recurrent mobility patterns.

Recently, there has been a lot of discussion about the nonlinearity property of contagion processes in epidemic spreading on social networks with various structures. In this paper, we propose a nonlinear contagion model in networked metapopulations to investigate the critical behavior of epidemics with recurrent mobility patterns. First, we build up a discrete-time Markovian chain model to formulate the spreading of susceptible-infected-susceptible-like diseases. Additionally, we develop a practicable framework to analyze the impact of mobility on the epidemic threshold and derive the theoretical condition for the transition of an epidemic from a local to a global scale. This transition is associated with multiple discontinuous phase changes. We validate our analytical results through extensive numerical simulations on both regular and heterogeneous networks. Our findings offer a useful tool to discuss the implementation of prevention strategies such as quarantine and lockdown.

Antibiotic resistance of Helicobacter pylori isolated from children in Chongqing, China.

The resistance of Helicobacter pylori (H. pylori) to antibiotics has been increasing worldwide and varies across different geographic areas and times. Limited studies reported the prevalence of antibiotic resistance and its related gene mutations in children in Chongqing, a city located in southwest China. We collected 112 H. pylori strains isolated from gastric biopsies of 156 children at Children's Hospital of Chongqing Medical University and calculated resistance rates of these strains to six antibiotics. The A2143G and A2142G mutations in 23S rRNA gene, which are related to clarithromycin resistance, and Asn87 and Asp91 mutations in gyrA gene, which are related to levofloxacin resistance, were investigated in 102 strains. The resistance rates to clarithromycin, metronidazole, and levofloxacin were 47.3% (53/112), 88.4% (99/112), and 18.8% (21/112), respectively. No resistance to amoxicillin, tetracycline, and furazolidone was observed. Dual and triple resistance percentages were 37.5% (42/112) and 10.7% (12/112), respectively. The detection rate of A2143G mutation in 23S rRNA gene was 83.3% (40/48). The detection rates of mutations of Asn87 and Asp91 in gyrA gene were 52.6% (10/19) and 36.8% (7/19), respectively. Conclusion: The prevalence of H. pylori resistance to clarithromycin, metronidazole, and levofloxacin was high in children in Chongqing, China. The A2143G mutation was detected in most clarithromycin-resistant strains, and Asn87 and Asp91 of gyrA mutation points were common in levofloxacin-resistant strains. In clinical practice, anti-H. pylori therapy should be individualized based on a susceptibility test.  What is Known: • The resistance of H. pylori to antibiotics changes with the geographic areas and that in Asia the resistance rate is high. • Mutation plays a vital role in antibiotics resistance of H. pylori. What is New: • High resistance rates to single and multiple antibiotics in children of Chongqing, a city located in southwest China, were observed. • Molecular assays showed good conformance with susceptibility test results to direct antibiotic resistance of H. pylori.

Review of microstructure and properties of low temperature lead-free solder in electronic packaging.

Low temperature solder (In-based, Sn-Bi, Sn-Zn) has great advantages in aerospace and through-hole technology assemblies in IBM mainframe due to its unique low temperature characteristics. The review evaluates the effects of alloying elements, rare earth elements and nanoparticles on the wettability, microstructure, mechanical properties and oxidation resistance of the low-temperature solders.

[Screening of common deaf genes in pregnant women and prevention of deafness at birth].

OBJECTIVE: To determine the carrier rate for common mutations causing deafness among pregnant women in order to prevent births of deaf children. METHODS: For 893 pregnant women, 2 mL peripheral venous blood was taken and DNA was extracted. A deafness DNA microarray screening was applied to such samples, and DNA sequencing was applied to husbands of women with positive screening results. RESULTS: A total of 40 carriers were detected, with the overall mutation rate being 4.48%. Among such carriers, GJB2 235delC was the most common heterozygous mutation (18 cases) and the mutation rate was 2.02%. GJB2 299A-T heterozygous mutation was detected in 7 cases with a mutation rate of 0.78%. IVS7-2A to G heterozygous mutation was detected in 9 cases with a mutation rate of 1.02%. There were 2 cases carrying GJB3 heterozygous mutation and 2 cases of mitochondrial 12S rRNA heterozygous mutation, with a mutation rate of 0.22%. IVS7-2A>G with GJB3 538C>T double heterozygous mutation was detected in 1 case, and IVS7-2A>G with GJB2 299A-T double heterozygous mutation was detected in another case, with the mutation rate of each being 0.11%. DNA sequencing has failed to find presence of mutations in the same gene in the husbands. The results of neonatal hearing follow-up were all normal. CONCLUSION: Applications of the deaf genes screening in pregnant women may play prove to be valuable for the early detection for neonatal deafness.

Biotype expression and insecticide response of Bemisia tabaci chemosensory protein-1.

Chemosensory proteins (CSPs) are a group of small soluble proteins found so far exclusively in arthropod species. These proteins act in chemical communication and perception. In this study, a gene encoding the Type 1 CSP (BtabCSP1) from the agricultural pest Bemisia tabaci (whitefly) was analyzed to understand sequence variation and expression specificity in different biotypes. Sequence analysis of BtabCSP1 showed significant differences between the two genetically characterized biotypes, B and Q. The B-biotype had a larger number of BtabCSP1 mutations than the Q-biotype. Similar to most other CSPs, BtabCSP1 was more expressed in the head than in the rest of the body. One-step RT-PCR and qPCR analysis on total messenger RNA showed that biotype-Q had higher BtabCSP1 expression levels than biotype-B. Females from a mixed field-population had high levels of BtabCSP1 expression. The interaction of BtabCSP1 with the insecticide thiamethoxam was investigated by analyzing the BtabCSP1 expression levels following exposure to the neonicotinoid, thiamethoxam, in a time/dose-response study. Insecticide exposure increased BtabCSP1 expression (up to tenfold) at 4 and 24 h following 50 or 100 g/ml treatments.

[Comparative study of prenatal diagnosis with single nucleotide polymorphism array and karyotype analysis].

OBJECTIVE: To compare the roles of single nucleotide polymorphism array (SNP array) and karyotype analysis in high-risk pregnant women prenatal diagnosis. METHODS: From July 2012 to December 2013, a total of 141 pregnant women with high-risk in prenatal diagnosis were selected as the object of study in Department of Obstetrics and Gynecology, Peking University Third Hospital, 78 cases of umbilical cord puncture and 63 of amnion cavity puncture , both taking SNP array detection and karyotype analysis. RESULTS: The abnormality karyotype rate was 6.4%, the abnormal rate of SNP array result was 11.3%, and the abnormal rate of the combined two methods for detecting was 12.1%. There were significant differences between the SNP array and karyotype analysis (P=0.039). CONCLUSION: There were obvious differences between the two techniques. It is an effective way to determine genetic disease by integrating SNP array and karyotype analysis in prenatal diagnosis.

Tanshinone IIA inhibits cell viability and promotes PUMA-mediated apoptosis of oral squamous cell carcinoma.

Apoptosis alteration is responsible for tumorigenesis and tumor resistance to therapies. The natural product Tanshinone IIA (Tan IIA) exhibits potent inhibitory effects against various tumors. However, the effect of Tan IIA on apoptosis and its underlying mechanism remains elusive in oral squamous cell carcinoma (OSCC). Here, we demonstrated that Tan IIA dose-dependently suppressed cell viability and colony formation in CAL27, SCC4, and SCC25 cells. Moreover, Tan IIA inhibited Akt activation from inducing Foxo3a dephosphorylation and PUMA-mediated apoptosis. PUMA or Foxo3a knockdown compromised the inhibitory effect of Tan IIA on OSCC cells. Tan IIA administration inhibited CAL27-deprived xenograft tumor growth and increased PUMA expression in vivo. Tan IIA synergistically intensified the efficacy of CDDP/5-FU-based chemotherapy on OSCC cells. Overall, our results revealed that Tan IIA exerted potent antitumor effects via promoting PUMA-mediated apoptosis in OSCC cells.

Soil fertility, salinity and nematode diversity influenced by Tamarix ramosissima in different habitats in an arid desert oasis.

The aim of this paper was to assess the influence of tamarisk shrubs on soil fertility, salinity and nematode communities in various habitats located in an arid desert-oasis region in northwest China. Three habitats were studied: sand dune, riparian zone and saline meadow, where tamarisk shrubs have been established in recent decades in order to vegetation restoration used as desertification control and saline land rehabilitation projects and become the dominant plant community. The parameters measured include soil organic carbon (SOC), total nitrogen, available phosphorus (P) and potassium (K), pH, salt component, and nematode community characteristics. Enrichment ratios (a comparison of the soil measurements between soils under canopy and in the open interspaces) for soil nutrients and salinity were used to evaluate fertility and salinity islands underneath the tamarisk shrubs. The soil nematode community was used as a biological indicator of soil condition. SOC and available P and K were higher beneath the plant canopy than in the open interspaces outside that canopy. The enrichment ratios for SOC and nutrients were highest for the sand dune habitat and tamarisk shrubs clearly created islands of greater salinity under the canopies. Nematode abundance per 100 g dry soil varied considerably between the locations and habitats, with the highest abundance found in sand dune and the lowest in saline meadow. A significantly higher nematode abundance and a lower trophic diversity were found in soils under the canopy compared to the soils in the open interspaces. With the exception of saline meadow, the abundance of bacterivores increased and fungivores decreased under the canopy relative to the open interspaces, and bacterivores dominated under the canopies in the sand dune and riparian habitats. The enrichment ratios for salinity were higher than for fertility, suggesting that improved soil fertility can not limit the impact of salinization beneath tamarisk shrubs. The adverse effect of salt accumulation on the soil environment should be taken into account when using tamarisk as restoration plant species, especially in saline meadow and controlling of tamarisk density should be considered when undertaking re-vegetation projects in the arid desert oasis regions.

Indirect transmission and disinfection strategies on heterogeneous networks.

Besides direct contacts of individuals, indirect contacts with environments being the medium is another route of epidemic transmission, which most previous studies have ignored. Disinfection is one of the most effective and commonly used measures to prevent and control epidemic spreading. In this paper, we propose a metapopulationlike model incorporating direct and indirect transmissions for susceptible-infected-susceptible-like epidemics on heterogeneous networks. Furthermore, we explore the epidemic spreading process with heterogeneous disinfection on both spatial and time dimensions. Specifically, we put forward three types of disinfection strategies, namely, the static disinfection strategy, the random time disinfection strategy, and the event-triggered disinfection strategy. Comparative analysis of the three strategies suggests that managers should prioritize disinfection resource allocation to large-flow environments, especially when disinfection resources are limited. In addition, timely disinfection of environments with infected visitors is an effective and economical strategy. Our model sheds light on the interplay dynamics of indirect transmission and disinfection and the results provide theoretical support for governors to select proper disinfection strategies in practical scenarios.

A phantom-based study and clinical implementation of brainlab's treatment planning system for radiosurgical treatments of arteriovenous malformations.

PURPOSE: Development of a simple, phantom-based methodology allowing for pilot applications for the Elements TPS cranio-vascular module and clinical implementation prior to AVM treatments. METHODS: A customized phantom was developed to be visible in MRI and CT images. High resolution digital subtraction angiograms (DSAs) and CT images of the phantom were acquired and imported into the Brainlab Elements treatment planning system. A clinical treatment plan with 5 arcs was generated in cranial vascular planning module and delivered to the phantom using a Varian TrueBeam STx Linac equipped with HD-MLCs and Brainlab ExacTrac imaging system for non-coplanar setup verification. The delivered dose was verified using a calibrated ionization chamber placed in the phantom. Upon verification of the TPS workflow, three patients with AVM who have been treated to date at our center using the Brainlab's cranial vascular module for AVM are presented here for retrospective review. RESULTS: The difference between the planed and measured dose by the ionization chamber was found to be less than 1%. Following a successful dose verification study, a clinical workflow was created. Currently, three AVM patients have been treated successfully. Clinical aspects of imaging and treatment planning consideration are presented in retrospective setting. CONCLUSIONS: Dose verification of the Brainlab Elements cranial vascular planning module for intracranial SRS treatments of AVM on Varian TrueBeam was successfully implemented using a custom-made phantom with <1% discrepancy. The Brainlab Elements' cranial vascular module was successfully implemented in clinical workflow to treat patients with AVM. This manuscript provides a guideline for clinical implementation of frameless Linac-based AVM treatment using the Brainlab Elements TPS.

Differential expression of serum GBP-28, NBP-Cyc 3 and TIMP-1 complicates pregnancy in hypertensive disorder pregnancy.

The current study is aimed at analyzing the correlation and differential expression of three entities namely, TIMP metallopeptidase inhibitor-1 (TIMP-1), a glycoprotein, serum adipokine (GBP-28), an amino acid protein and neuroendocrine basic polypeptide NBP-cystatin3 (NBP-Cyc 3) in HDP (Hypertensive Disorders complicating Pregnancy). A total of 63 patients, diagnosed with HDP at the study hospital during the study period, was placed under treatment (HDP) group. While healthy group had a total of 50 women with normal pregnancy during the same period. Both these groups were compared in terms of GBP-28, TIMP-1 and NBP-Cyc 3 levels. Further, the author also checked the correlation, diagnostic value and prognosis for the three factors and HDP. There was a significant increase observed in the expression levels of serum TIMP-1 and NBP-Cyc 3 in HDP during ELISA compared to GB. However, HDP group recorded low value of serum GBP-28 than healthy group (all P < 0.001). There is a relationship between the expressions of GBP-28, TIMP-1 and NBP-Cyc 3 and the abnormalities in lipid and glucose metabolisms, resulting in severe clinical conditions among HDP patients. The inference from spearman correlation analysis is that serum GBP-28 and the severity of HDP are negatively correlated. While Serum TIMP-1 and NBP-Cyc 3 had a positive correlation with the severity of HDP (all P < 0.001). When diagnosing HDP, the AUC values of both GBP-28 and NBP-Cyc 3 single diagnosis were above 0.8. Multivariate conditional logistic regression was deployed to assess the risk factors associated with HDP. The results listed the independent risk factors such as GBP-28, TIMP-1 and NBP-Cyc 3 and disease severity for the prognosis of HDP. Among HDP patients, upregulated expressions of serum TIMP-1and NBP-Cyc 3 were observed while in case of GBP-28, it was vice versa. The significant role, played by GBP-28, TIMP-1 and NBP-Cyc 3 in the progression of HDP, makes these entities potential serum biomarkers in diagnosis and assessment of HDP.

miR­21 inhibits autophagy and promotes malignant development in the bladder cancer T24 cell line.

MicroRNA­21 (miR­21) is reported to exhibit cancer­promoting activity in various types of cancer. It has been previously demonstrated that miR­21 is overexpressed in bladder tumor tissue compared with normal mucosa. However, the functional mechanism of miR­21 in bladder cancer remains largely unknown. Thus, the current study aimed to determine the roles of miR­21 in autophagy and the malignant development of bladder cancer in T24 cells. Upregulation or downregulation of miR­21 was achieved following the transfection of miR­21 mimic or miR­21 inhibitor. An MTT assay was additionally performed to measure cell growth. Wound healing and transwell invasion assays were used to detect cell migration and invasion. The apoptotic potential and cell cycle were examined via flow cytometry and reverse transcription­quantitative PCR was performed to evaluate the expression of phosphatase and tensin homolog (PTEN), beclin 1, microtubule­associated protein l light chain 3B (LC3­II), cyclin D1, caspase­3, E­cadherin, matrix metallopeptidase­9 (MMP­9) and vimentin. The results revealed that the proliferation, migration and invasion of T24 cells was greatly increased in the miR­21 mimic group, while apoptosis was greatly inhibited. Additionally, T24 cells treated with miR­21 mimic exhibited G1­phase arrest. In the miR­21 mimic group, the expression of PTEN, beclin 1, LC3­II, caspase­3 and E­cadherin were decreased, while the expression of cyclin D1, MMP­9 and vimentin were increased. Opposite effects were observed in the miR­21 inhibitor group. The data of the current study may indicate that miR­21 overexpression inhibited autophagy and promoted the proliferation, migration, invasion and epithelial to mesenchymal transition of bladder cancer T24 cells. The results may further elucidate the molecular mechanism of miR­21 in the development of bladder cancer.

Potent antitumor activity of double-regulated oncolytic adenovirus-mediated ST13 for colorectal cancer.

Following targeted gene virotherapy, the suppression of tumorigenicity 13 (ST13) gene was inserted into the double-regulated oncolytic adenovirus SG500 to ensure more safety and potent antitumor activity against colorectal cancer in vitro and in vivo. We generated the ST13-expressing oncolytic adenovirus SG500-ST13, with which colorectal carcinoma cell lines SW620 and HCT116, and the lung fibroblast cell line WI38, were infected. Crystal violet staining was carried out to detect the cytopathic effect in cells, and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method was used to assay cell viability. The effect of apoptosis induced by SG500-ST13 was confirmed by Hoechst staining and the TdT-mediated dUTP-biotin nick-end labeling method. To further identify the antitumor effects of SG500-ST13 on HCT116 xenografts in Balb/c nude mice, the induction of cell death was assessed by hematoxylin-eosin staining. Immunohistochemical study was also carried out.

[Hyperglycemia at admission and outcome in elderly patients with acute ST segment elevation myocardial infarction underwent primary percutaneous coronary intervention].

OBJECTIVE: To investigate the association between hyperglycemia and outcome in elderly patients with acute ST segment elevation myocardial infarction (STEMI) underwent primary percutaneous coronary intervention (PCI). METHODS: This retrospective analysis was performed on 284 elderly patients (age > or = 60 years) with acute STEMI underwent primary PCI between January 2000 to April 2004 in our department. Patients were divided into 3 groups according to the level of blood glucose on admission: group A, < 7.8 mmol/L; group B, 7.8 - 10.9 mmol/L; group C, > or = 11.0 mmol/L. RESULTS: (1) The proportion of female in group B and group C was greater than that of group A (33.3% vs. 26.5%, P < 0.01; 40.2% vs. 26.5%, P < 0.01). The hospital stay time of group B and group C was significantly longer than that of group A (16.0 days vs. 13.9 days, P < 0.05; 16.6 days vs. 13.9 days, P < 0.05). There were more patients with history of hypertension in group C than that in group A (72.1% vs. 54.9%, P < 0.01). (2) After PCI, the proportion of patients with TIMI myocardial perfusion grade (TMPG) 0-1 in group B and C was greater than that of group A (22.6% vs. 13.3%, P < 0.05; 34.1% vs. 13.3%, P < 0.05). The proportion of patients with TMPG 3 in group B and C was less than that in group A (74.3% vs. 84.4%, P < 0.05; 57.6% vs. 84.4%, P < 0.05). The complication rate of PCI was significantly higher in group C than in group A (42.5% vs. 20.6%, P < 0.01) and group B (42.5% vs. 26.6%, P < 0.01). IABP use was significantly more in group C than that in group A (19.5% vs. 4.9%, P < 0.01) and group B (19.5% vs. 6.4%, P < 0.01). (3) There were more patients with grade of Killip class > or = 2 in group C than that in group A (44.8% vs. 23.5%, P < 0.01) and group B (44.8% vs. 27.7%, P < 0.01). The in-hospital mortality rate (8.0% vs. 1.1%, P < 0.05) and one-year mortality rate (18.7% vs. 3.4%, P < 0.05) of group C were significantly higher than those in group A. CONCLUSION: Hyperglycemia at admission was associated with poor tissue perfusion, cardiac function and prognosis in elderly patients with acute STEMI underwent primary PCI.

Wide-field auroral imager onboard the Fengyun satellite.

The newly launched Fengyun-3D (FY-3D) satellite carried a wide-field auroral imager (WAI) that was developed by Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences (CIOMP), which will provide a large field of view (FOV), high spatial resolution, and broadband ultraviolet images of the aurora and the ionosphere by imaging the N2 LBH bands of emissions. The WAI consists of two identical cameras, each with an FOV of 68° in the along-track direction and 10° in the cross-track direction. The two cameras are tilted relative to each other to cover a fan-shaped field of size 130° × 10°. Each camera consists of an unobstructed four-mirror anastigmatic optical system, a BaF2 filter, and a photon-counting imaging detector. The spatial resolution of WAI is ~10 km at the nadir point at a reference height of 110 km above the Earth's surface. The sensitivity is >0.01 counts s-1 Rayleigh-1 pixel-1 (140-180 nm) for both cameras, which is sufficient for mapping the boundaries and the fine structures of the auroral oval during storms/substorms. Based on the tests and calibrations that were conducted prior to launch, the data processing algorithm includes photon signal decoding, geometric distortion correction, photometric correction, flat-field correction, line-of-sight projection and correction, and normalization between the two cameras. Preliminarily processed images are compared with DMSP SSUSI images. The agreement between the images that were captured by two instruments demonstrates that the WAI and the data processing algorithm operate normally and can provide high-quality scientific data for future studies on auroral dynamics.

Relation of hyperglycemia to ST-segment resolution after primary percutaneous coronary intervention for acute myocardial infarction.

BACKGROUND: Hyperglycemia has been shown to be a powerful predictor of poor outcome after ST-segment elevation myocardial infarction (STEMI). This study aimed to evaluate the effect of admission glucose on microvascular flow after successful primary percutaneous coronary intervention (PCI) in patients with STEMI. METHODS: Successful primary PCI was performed in 267 patients with STEMI. The maximum ST elevation of single electrocardiogram (ECG) lead before and 60 minutes after PCI was measured, and patients were then divided into 3 groups according to the degree of ST-segment resolution (STR): absent (<30%), partial (30% to 70%) or complete (> or =70%). RESULTS: Of the 267 patients, 48 (18.0%) had absent STR, 137 (51.3%) experienced partial STR, and 82 (30.7%) had complete STR. The degree of STR decreased with increasing admission glucose levels (P=0.032), and patients with hyperglycemia (serum glucose level > or =11 mmol/L) were more likely to have absent STR (P=0.001). Moreover,hyperglycemia was an independent predictor of incomplete STR (odds ratio, 1.870; 95% confidence interval, 1.038 to 3.371, P=0.037). CONCLUSIONS: Hyperglycemia on admission is associated with abnormal coronary microvascular reperfusion in patients with STEMI after successful primary PCI, which may contribute, at least in part, to the poor outcomes in these patients.

Cu6Sn5 Whiskers Precipitated in Sn3.0Ag0.5Cu/Cu Interconnection in Concentrator Silicon Solar Cells Solder Layer.

Cu6Sn5 whiskers precipitated in Sn3.0Ag0.5Cu/Cu interconnection in concentrator silicon solar cells solder layer were found and investigated after reflow soldering and during aging. Ag3Sn fibers can be observed around Cu6Sn5 whiskers in the matrix microstructure, which can play an active effect on the reliability of interconnection. Different morphologies of Cu6Sn5 whiskers can be observed, and hexagonal rod structure is the main morphology of Cu6Sn5 whiskers. A hollow structure can be observed in hexagonal Cu6Sn5 whiskers, and a screw dislocation mechanism was used to represent the Cu6Sn5 growth. Based on mechanical property testing and finite element simulation, Cu6Sn5 whiskers were regarded as having a negative effect on the durability of Sn3.0Ag0.5Cu/Cu interconnection in concentrator silicon solar cells solder layer.

Effects of CuZnAl Particles on Properties and Microstructure of Sn-58Bi Solder.

With the purpose of improving the properties of the Sn-58Bi lead-free solder, micro-CuZnAl particles ranging from 0 to 0.4 wt % were added into the low temperature eutectic Sn-58Bi lead-free solder. After the experimental testing of micro-CuZnAl particles on the properties and microstructure of the Sn-58Bi solders, it was found that the wettability of the Sn-58Bi solders was obviously improved with addition of CuZnAl particles. When the addition of CuZnAl particles was 0.2 wt %, the wettability of the Sn-58Bi solder performed best. At the same time, excessive addition of CuZnAl particles led to poor wettability. However, the results showed that CuZnAl particles changed the melting point of the Sn-58Bi solder slightly. The microstructure of the Sn-58Bi solder was refined by adding CuZnAl particles. When the content of CuZnAl addition was between 0.1 and 0.2 wt %, the refinement was great. In addition, the interfacial IMC layer between new composite solder and Cu substrate was thinner than that between the Sn-58Bi solder and Cu substrate.