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Reliability testing and failure modelling is crucial and very challenging for modern electronics, especially safety critical electronics-based systems working under harsh environmental conditions. In this paper, an approach based on ultrasonic Non-Destructive Evaluation (NDE) is proposed to establish a failure model for solder joints which is urgently needed for prognostic and health management of electronics. Printed Circuit Boards (PCB) containing flip-chip and Area Array packages were designed and aged using Accelerated Thermal Cycling (ATC) testing. During ATC testing solder joint degradation was regularly monitored by taking out the test boards from the temperature chamber at four thermal cycle intervals for ultrasonic micro-imaging. Data pre-processing techniques including dynamic range-based intensity normalization, gain compensation, and calibration for random transducer defocusing errors were developed to enhance the data consistency, integrity and accuracy. Furthermore, solder joint image labelling and segmentation methods were developed by exploiting the geometrical features of the solder joints to extract individual solder joints and Region of Interests (ROIs) from the sequential ultrasound images collected throughout the testing. The mean intensity of the ROIs was used as the precursor to degradation to build the solder joint failure model, from which cycles to failure for individual solder joints are finally derived for life prediction. [ABSTRACT FROM AUTHOR]

The miniaturization and three dimensional die stacking in advanced microelectronic packages poses a big challenge to their non-destructive evaluation by acoustic microimaging. In particular, their complicated structures and multiple interfaces make the interpretation of acoustic data even more difficult. A common phenomenon observed in acoustic microimaging of microelectronic packages is the edge effect phenomena, which obscures the detection of defects such as cracks and voids. In this paper, two dimensional finite element modelling is firstly carried out to numerically simulate acoustic microimaging of modern microelectronic packages. A flip-chip with a 140 µm solder bump and a 230 MHz virtual transducer with a spot size of 16 µm are modelled. Crack propagation in the solder bump is further modelled, and B-scan images for different sizes of micro-cracks are obtained. C-line plots are then derived from the simulated B-scan images to quantitatively analyze the edge effect. Gradual progression of the crack is found to have a predictable influence on the edge effect profile. By exploiting this feature, a crack propagation characterization method is developed. Finally, an experiment based on the accelerated thermal cycling test is designed to verify the proposed method. [ABSTRACT FROM AUTHOR]

Edge effect is a common phenomenon observed in acoustic micro-imaging of microelectronic packages. In this paper, using flip chip package geometry as a test vehicle, finite element modelling is carried out to study the fundamental mechanism of the edge effect phenomenon. C-Line plot technique is developed for the characterization of edge effects in acoustic C-scan images, in particular solder joint C-scan images. Simulated results are compared to experimental results. Results reveal that edge effect generation is mainly attributed to the under-bump-metallisation structure. In addition, through analysis of the C-Line profile of edge effects, the impact of the transducer focal point and the spot size on the edge effect is investigated. Results show that slight off-focus can reduce the severity of the edge effect in which image sharpness is a trade-off. [ABSTRACT FROM AUTHOR]

Abstract: One of the difficulties in light pen 3D vision measurement is the stereo matching of the light-spot image points. Therefore, the SoftPoist algorithm is adopted to determine the corresponding relations of the light-spot image point in the left and right images to the spatial light spots through double-layer circulation iterative optimization, and then solve the stereo matching problem. The SoftPoist algorithm improves the POSIT algorithm so that the improved algorithm can be applied to huge amounts of light-spot feature points where the corresponding relations of the image points to its object unknown. The iterative optimization of the matching and pose estimation parameters can be computed if only there are four noncoplanar feature points, so the applied scope of the improved algorithm is much wider. The experiment results show that the algorithm can keep the measurement accuracy and shorten the time of the program operation to enhance matching efficiency and the improved algorithm has the practical value. [Copyright &y& Elsevier]

Abstract: We show that there is a topological (Berry phase) term in the non-linear σ model description of the spin chain. It distinguishes the linear and projective representations of the symmetry group, in exact analogy to the well-known θ-term of the spin chain. The presence of the topological term is due to the fact that . We discuss the implication of our results on the spectra of the spin chain, and connect it with a recent solvable spin model which exhibits valence bond solid ground state and edge degeneracy. [Copyright &y& Elsevier]

Abstract: In a highly competitive market, reliable techniques for manufacturing quality control of electronic devices are demanded. Characterisation of modern microelectronic package integrity becomes more difficult due to the continued miniaturisation of electronic device and the complexity of advanced micro-assembling technologies such as chip-scale packages and 3D IC stacks. In this paper, sparse representations of acoustic signals are sought to improve the scanning acoustic microscopy (SAM), a common non-destructive tool for failure analysis of microelectronic packages. Sparse representation of an ultrasonic signal is obtained by decomposing it in an overcomplete dictionary. Detection and location of ultrasonic echoes are then performed on the basis of the resulting redundant representation. The method offers a solution to the deconvolution problem for restoration of the ultrasonic reflectivity function. It can restore closely space overlapping echoes beyond the resolution of the conventional SAM system. It also produces high resolution and accurate estimates for ultrasonic echo parameters, i.e., time-of-flight, amplitude, centre frequency, and bandwidth. These merits of the proposed method are explored in various potential applications for microelectronic package characterisation. [Copyright &y& Elsevier]

Abstract: Acoustic microimaging (AMI) is used as an important non-destructive tool in semiconductor reliability evaluation and failure analysis. As advanced microelectronic packages are being produced smaller and thinner, detection of the internal features and defects in the packages is approaching the resolution limits for conventional AMI. To meet this challenge, an acoustic time–frequency domain imaging technique is proposed in this paper, which utilizes the excellent time–frequency localization characteristics of the continuous wavelet transform (CWT) to improve the axial resolution of AMI, without increasing acoustic frequencies. The proposed technique is compared to time domain AMI, frequency domain AMI and sparse signal representation based AMI (SSRAMI) with respect to both axial resolution and robustness. Simulation results show that the proposed technique has superior performance compared to time domain and frequency domain AMI techniques, and has close performance to SSRAMI but with less computation load. [Copyright &y& Elsevier]

In this paper, two categories of transform coding and subband coding are comparatively studied for compressing ultrasonic NDE images. The data compression performance of the discrete cosine transform-, the Karhunen-Loève transform-, and the discrete wavelet transform-based codecs are examined by being applied to ultrasonic NDE images. The effects of these compression methods on the analysis of ultrasonic information in compressed ultrasonic images are examined. Moreover, evaluation of the main elements in image coding system is performed to explore the important factors, which are worth paying more attention when developing a special image compression technique for ultrasonic NDE images. [Copyright &y& Elsevier]

We conducted a phase I, randomized, double-blind, placebo-controlled trial including healthy adults in Sui County, Henan Province, China. Ninety-six adults were randomly assigned to one of three groups (high-dose, medium-dose, and low-dose) at a 3:1 ratio to receive one vaccine dose or placebo. Adverse events up to 28 days after each dose and serious adverse events up to 6 months after all doses were reported. Geometric mean titers and seroconversion rates were measured for anti-rotavirus neutralizing antibodies using microneutralization tests. The rates of total adverse events in the placebo group, low-dose group, medium-dose group, and high-dose group were 29.17 % (12.62 %–51.09 %), 12.50 % (2.66 %–32.36 %), 50.00 % (29.12 %–70.88 %), and 41.67 % (22.11 %–63.36 %), respectively, with no significant difference in the experimental groups compared with the placebo group. The results of the neutralizing antibody assay showed that in the adult group, the neutralizing antibody geometric mean titer at 28 days after full immunization in the low-dose group was 583.01 (95 % confidence interval [CI]: 447.12–760.20), that in the medium-dose group was 899.34 (95 % CI: 601.73–1344.14), and that in the high-dose group was 1055.24 (95 % CI: 876.28–1270.75). The GMT of serum-specific IgG at 28 days after full immunization in the low-dose group was 3444.26 (95 % CI: 2292.35–5175.02), that in the medium-dose group was 6888.55 (95 % CI: 4426.67–10719.6), and that in the high-dose group was 7511.99 (95 % CI: 3988.27–14149.0). The GMT of serum-specific IgA at 28 days after full immunization in the low-dose group was 2332.14 (95 % CI: 1538.82–3534.45), that in the medium-dose group was 4800.98 (95 % CI: 2986.64–7717.50), and that in the high-dose group was 3204.30 (95 % CI: 2175.66–4719.27). In terms of safety, adverse events were mainly Grades 1 and 2, indicating that the safety of the vaccine is within the acceptable range in the healthy adult population. Considering the GMT and positive transfer rate of neutralizing antibodies for the main immunogenicity endpoints in the experimental groups, it was initially observed that the high-dose group had higher levels of neutralizing antibodies than the medium- and low-dose groups in adults aged 18–49 years. This novel inactivated rotavirus vaccine was generally well-tolerated in adults, and the vaccine was immunogenic in adults (ClinicalTrials.gov number, NCT04626856). [ABSTRACT FROM AUTHOR]

Abstract: Acoustic Micro Imaging (AMI) techniques have been widely used as a non destructive evaluation (NDE) tool in evaluating both microelectronic packages and solder joints. However, there are a lack of analysis tools and automated inspection techniques to facilitate the inspection process. This paper presents a novel approach to extract the solder joint’s features from ultrasound images for automated solder joint assessment. The proposed method consists of three stages: solder joint detection, feature extraction, and defect evaluation. Firstly, a gradient based circular Hough transform is employed to detect the solder joints in acquired ultrasound images. Subsequently, feature extraction is carried out by a radial gradient based region growing algorithm. Finally, defect evaluation is achieved by analysing the variation of the image features automatically. Cross-sectional analysis was performed to validate and evaluate the performance of the solder joint inspection system. The results show that image features obtained by the system can be used easily to distinguish between a healthy and fractured joint, thus confirming the feasibility of the automated AMI inspection technique. [Copyright &y& Elsevier]

Abstract: High-speed counter-current chromatography (HSCCC) is applied to the purification of coenzyme Q10 (CoQ10) for the first time. CoQ10 was obtained from a fermentation broth extract. A non-aqueous two-phase solvent system composed of heptane–acetonitrile–dichloromethane (12:7:3.5, v/v/v) was selected by analytical HSCCC and used for purification of CoQ10 from 500mg of the crude extract. The separation yielded 130mg of CoQ10 at an HPLC purity of over 99%. The overall results of the present studies show the advantages of HSCCC over an alternative of silica gel chromatography followed by recrystallization. These advantages extend to higher purity (97.8% versus 93.3%), recovery (88% versus 74.3%) and yield (26.4% versus 23.4%). An effort to avoid the toxic, expensive solvent CH2Cl2 was unsuccessful, but at least its percentage is low in the solvent system. [Copyright &y& Elsevier]

As two emerging pollutants of great concern, microplastics (MPs) and antibiotics inevitably cooccur in various aquatic environments and interact with each other, impacting the fate and ecological risks. Aging obviously complicates their interaction and deserves further study. Therefore, the adsorption-desorption behaviors of ciprofloxacin (CIP) onto polystyrene (PS) fragments with various aging extent were investigated, and the key physiochemical properties influencing the interaction and the interaction mechanisms were clarified by redundancy analysis, FTIR and XPS spectra. The physicochemical properties of PS MPs were significantly changed with aging time, and the morphological and chemical changes seemed to occur asynchronously. The adsorption of CIP onto the pristine PS MPs relied on physisorption, especially the ion-involving electrostatic and cation-π interaction. Due to the hydrogen bonding formed by the C–OH, C O, and O–C O groups of PS and CIP, the adsorption capacities of the aged PS MPs were greatly increased. The desorption efficiency of CIP from MPs in the gastric fluid was closely related to the solution ionic strengths, C–OH and C O groups of MPs, while that in the intestinal fluid was associated with O–C O groups of MPs. The different impact factors could be well described by the differences in the chemical components and pHs of the simulated gastric and intestinal fluids. This study gives a comprehensive understanding of the adsorption-desorption behaviors of antibiotics onto MPs at a molecular level and indicates that MPs could act as Trojan horses to transport antibiotics into aquatic organisms. [Display omitted] • Redundancy analysis identified MPs' key properties affecting adsorption/desorption. • Hydrogen bonding, electrostatic and cation-π interaction were crucial for CIP adsorption. • The C–OH, C O, and O–C O groups of aged MPs were involved in the hydrogen bonding with CIP. • Desorption of CIP in the gastric fluid relied on the C–OH and C O groups of MPs. • Desorption of CIP in the intestinal fluid was related to the O–C O groups of MPs. [ABSTRACT FROM AUTHOR]

This study aimed to investigate whether a selective delta opioid receptor agonist, [D-Ala2, D-Leu5]-Enkephalin (DADLE), regulates neurogenesis in the hippocampus of ischemic rats. Using an intracerebral cannula, rats were subjected to cerebral ischemia using the standard four-vessel occlusion. DADLE (2.5 nmol), DADLE (2.5 nmol) with naltrindole (NAL) (2.5 nmol), or vehicle was administered at the onset of reperfusion. Bromodeoxyuridine (BrdU, 100 mg/kg, intraperitoneal) was used to label newly formed cells from days 1 to 7 after ischemia. Immunohistochemistry was used to evaluate cell proliferation and apoptosis and differentiation 7 days 28 days, respectively, after ischemia. Morris water maze test was conducted to test spatial learning and memory 23–27 days after ischemia. We found that DADLE treatment improved performance in the Morris water maze test, promoted proliferation and differentiation of newly formed neurons, and inhibited differentiation into astrocytes in a rat model of cerebral ischemia. Furthermore, the protective effects of DADLE were significantly reversed by co-administration of NAL (P < 0.05), a highly potent and selective delta opioid receptor antagonist. Our findings suggest that DADLE promotes spatial cognitive function recovery and regulates neurogenesis after ischemia, which may provide a promising therapeutic strategy for cerebral ischemia. [ABSTRACT FROM AUTHOR]

Trace-organic contaminants elimination effectiveness and their removal pathways in a powder-activated carbon-membrane bioreactor (PAC-MBR) used for micro-polluted surface water treatment were investigated in this study. The results showed that PAC-MBR was capable of consolidating DOM elimination, enhancing trace-organic contaminants (2,4,6-trichlorophenol, nitrobenzene and trichloroethylene) removal efficiency, improving permeate biostability, and decreasing bulk organic content and specific fractional components, which was beneficial for membrane fouling mitigation. By series of well-designed batch-tests and estimation, trace-organics removal pathways were analyzed. The primary way of TCE removal was aeration volatilization, while that of NB and 2,4,6-TCP elimination was biodegradation which was greatly affected by biomass content within bulk. PAC addition was a positive way for effective trace-organics removal by increasing mixed solid adsorption capability, especially in start-up phase, and offering beneficial circumstances for biomass enrichment and functional bacteria accumulation. Thus, PAC addition into MBR is a simple and effective strategy to treat micro-polluted water resources. [ABSTRACT FROM AUTHOR]

Abstract: l-Asparaginase II of E. coli is a kind of effective drug in the treatment of acute lymphoblastic leukaemia. However, during asparaginase therapy, repeated using of the drug is commonly needed because of the enzyme''s relatively short half-life and instability in the processes of production and treatment. This leads to more serious toxic effects on patients. In order to stabilize the enzyme, a higher thermostable mutant l-asparaginase II was created in the present study by replacing Asp178 with proline in a hydrogen-bonded turn (178–180DGR) which is contribute to the thermostability of the enzyme. The results displayed that values of K m and K cat for the mutant enzyme are not affected although the energy of activation is increased comparing to the wild-type enzyme. These data suggest that such alteration for l-asparaginase II enhances the thermostability of the enzyme without changing the enzyme''s activity and thus the therapeutical use of l-asparaginase II might be benefit from these results. [Copyright &y& Elsevier]