Evaluation of flip-chip bonding electrical connectivity for ultra-large array infrared detector.

Flip-chip bonding is a key technology for infrared focal plane array (IRFPA) detectors. Due to the high cost of device preparation, the ultra-large array infrared detector cannot be directly used for the flip-chip bonding experiment, and the connectivity rate cannot be measured. To evaluate the flip-chip bonding process, a test device which has the same interconnecting structure as current IRFPA detectors is proposed. Indium bumps are electrically extracted to test electrodes. Electrical measurements were performed to characterize the connection and adhesion of the indium bumps and to calculate the connectivity rate. The electrical connectivity characteristics of the test devices correspond to the observation results of the indium bump extrusion, effectively detecting the interconnecting anomalies such as disconnection, adhesion, overall misalignment, etc., and verifying the feasibility of the test method. The test device has similar multi-layer components and thermal properties as HgCdTe infrared detector for process evaluation and post-processing experiment. The connectivity rate of the test device is up to 100%, and remains above 99% after thermal recycle experiment. The contact resistance of the interconnecting structure is calculated to be about 31.84 Ω based on the test results.

Systematic prediction method for flip-chip bonding connectivity of ultra-large array infrared detector.

The flip-chip bonding technique utilized in ultra-large array infrared detectors has a substantial impact on connectivity rates. The electrical connectivity of the flip-chip bonding process exhibits randomness due to the difficulties in the surface control of large-scale devices. This restriction hinders the development of ultra-large array devices. In this work, the surface shape matching calculation is performed based on the surface shape distributions measured from infrared detector chips and readout circuits. The multi combinations and multi rotation angles are employed to calculate the distribution of combined surface distances, and the combined PV (peak-to-valley) value is applied to describe the severity of surface mismatch. Test devices with combined PV values ranging from 7.460 µm to 4.265 µm are prepared and tested, and the connectivity rate achieves an improvement from 74.57% to 99.75% between mismatched devices and matching devices. The electrical test results of test devices indicate that disconnections tend to cluster in areas where surface distance is over 5 µm, which is determined by extracting and analyzing the surface distance correlated to electrical test results. A standard based on the combined PV value is established to select matching combinations and ensure a high connectivity rate of 99% or 97% for infrared detectors, while the connectivity rates of randomly selected devices are no higher than 91%. This work presents a systematic method to predict and improve the connectivity rate of flip-chip bonding process for ultra-large array infrared detector.

Attributable causes of colorectal cancer in China.

BACKGROUND: Colorectal cancer is the 4th common cancer in China. Most colorectal cancers are due to modifiable lifestyle factors, but few studies have provided a systematic evidence-based assessment of the burden of colorectal cancer incidence and mortality attributable to the known risk factors in China. METHODS: We estimated the population attributable faction (PAF) for each selected risk factor in China, based on the prevalence of exposure around 2000 and relative risks from cohort studies and meta-analyses. RESULTS: Among 245,000 new cases and 139,000 deaths of colorectal cancer in China in 2012, we found that 115,578 incident cases and 63,102 deaths of colorectal cancer were attributable to smoking, alcohol drinking, overweight and obesity, physical inactivity and dietary factors. Low vegetable intake was the main risk factor for colorectal cancer with a PAF of 17.9%. Physical inactivity was responsible for 8.9% of colorectal cancer incidence and mortality. The remaining factors, including high red and processed meat intake, low fruit intake, alcohol drinking, overweight/obesity and smoking, accounted for 8.6%, 6.4%, 5.4%, 5.3% and 4.9% of colorectal cancer, respectively. Overall, 45.5% of colorectal cancer incidence and mortality were attributable to the joint effects of these seven risk factors. CONCLUSIONS: Tobacco smoking, alcohol drinking, overweight or obesity, physical inactivity, low vegetable intake, low fruit intake, and high red and processed meat intake were responsible for nearly 46% of colorectal cancer incidence and mortality in China in 2012. Our findings could provide a basis for developing guidelines of colorectal cancer prevention and control in China.

Direct mapping and characterization of dry etch damage-induced PN junction for long-wavelength HgCdTe infrared detector arrays.

Mercury cadmium telluride is the standard material to fabricate high-performance infrared focal plane array (FPA) detectors. However, etch-induced damage is a serious obstacle for realizing highly uniform and damage-free FPA detectors. In this Letter, the high signal-to-noise ratio and high spatial resolution scanning photocurrent microscopy (SPCM) is used to characterize the dry etch-induced inversion layer of vacancy-doped p-type Hg1-xCdxTe (x=0.22) material under different etching temperatures. It is found that the peak-to-peak magnitude of the SPCM profile decreases with a decrease in etching temperature, showing direct proof of controlling dry etch-induced type conversion. Our work paves the way toward seeking optimal etching processes in large-scale infrared FPAs.

[Time-series analysis of particulate matter and daily hospital visits for coronary heart disease in Yinzhou district, Ningbo area].

Objective: To explore the association between particulate matter (PM) and daily hospital visits of coronary heart diseases in Ningbo. Methods: Daily data of hospital visits from January 2014 to June 2015 (516 days in total) were obtained from the Yinzhou Health Information System in Ningbo. Daily air pollution data for PM and meteorological data were collected from the database of Ningbo Environmental Monitoring Center and Ningbo Meteorological Bureau. Time-series analysis by quasi-Poisson generalized additive model was used to examine the association between air pollution and hospital visits for coronary heart diseases by adjustment of long-term trends, seasonal patterns and meteorological variables (temperature, humidity), and day of week. Results: An increase of an IQR of PM2.5 accounted for 1.98% (95%CI:-0.59%-4.63%) increase of hospital visits for coronary heart diseases. The associations between PM2.5 and hospital visits for coronary heart diseases among female and the elderly (≥75 years) were stronger (ER=2.70%,95% CI:0.01%-5.47%; ER=3.35%, 95% CI: 0.12%-6.69%). The effects of PM2.5~10 attenuated after adjustment for PM2.5.Conclusion: PM2.5 had short-term effects on daily hospital visits for coronary heart diseases in Ningbo, and such association was stronger among female and the elderly.

128 × 128 long-wavelength/mid-wavelength two-color HgCdTe infrared focal plane array detector with ultralow spectral cross talk.

High temporal and spatial coherent simultaneous long-wavelength/mid-wavelength (LW/MW) two-color focal plane array (FPA) infrared detection is the cutting-edge technique for third-generation infrared remote sensing. In this Letter, HgCdTe LW/MW two-color infrared detectors were designed and fabricated. The top long-wavelength and bottom mid-wavelength infrared planar photodiodes were processed by selective B(+)-implantation after etching the long-wavelength epilayer into a curvature and exposing the mid-wavelength layers for the implantation of the n region of the MW photodiode by a micro-mesa array technique. A 128×128 MW/LW HgCdTe infrared FPA detector is fabricated photo-lithographically by simultaneous nonplanar B(+)-implantation of the LW and MW photodiodes, passivation and metallization of the sidewalls, mesa isolation, and flip-chip hybridization with a read-out integrated circuit. The inner mechanisms for suppressing the cross talk and improving photoresponse have been carried out by combining experimental work with numerical simulations.

The value of Apolipoprotein B/Apolipoprotein A1 ratio for metabolic syndrome diagnosis in a Chinese population: a cross-sectional study.

BACKGROUND: The apoB/apoA1 ratio has been reported to be associated with the metabolic syndrome (MetS), and it may be a more convenient biomarker in MetS predicting. However, whether apoB/apoA1 ratio is a better indicator of metabolic syndrome than other biomarkers and what is the optimal cut-off value of apoB/apoA1 ratio as an indicator of metabolic syndrome in Chinese population remain unknown. Thus, we carried out the current study to assess the predictive value of apoB/apoA1 ratio and determine the optimal cut-off value of apoB/apoA1 ratio for diagnosing MetS in a Chinese population. METHOD: We selected 1,855 subjects with MetS and 6,265 individuals without MetS based on the inclusion and exclusion criteria from the China Health Nutrition Survey (CHNS) in 2009. MetS was identified based on the diagnostic criteria of International Diabetes Federation (2005). Logistic regression was used to estimate the association between the apoB/apoA1 ratio and risk of MetS, and receiver operating characteristics (ROC) curve analysis was performed to test the predictive value of apoB/apoA1 ratio and calculate the appropriate cut-off value. RESULTS: Compared with the lowest quartile of apoB/apoA1 ratio, subjects in the fourth quartile had a higher risk of MetS in both men [odds ratio (OR) = 2.64, 95% confidence interval (CI) =1.82-3.83] and women (OR = 5.18, 95% CI = 3.87-6.92) after adjustment for potential confounders. The optimal cut-off value of apoB/apoA1 ratio for MetS detection was 0.85 in men and 0.80 in women. Comparisons of ROC curves indicated that apoB/apoA1 ratio was better than traditional biomarkers in predicting MetS. CONCLUSION: Our results suggest that, apoB/apoA1 ratio has a promising predictive effectiveness in detection of MetS. An apoB/apoA1 ratio higher than 0.85 in men and 0.80 in women may be a promising and convenient marker of MetS.

Laboratory Experiments and Numerical Simulation on Dynamic Response of Island Reclamation Coral Sand under Aircraft Load.

The construction of island airports on coral reefs inevitably encounters the impact load of aircraft takeoff and landing. However, previous studies have not presented a detailed description of the dynamic response of the coral sand beneath the runways of island reclamation airports under aircraft load. In the current study, the coral sand of Mischief Reef Airport in the Nansha Islands, China, was selected as the background. The pore water pressure and strain characteristics of reshaped coral sand under aircraft loads with different dynamic stress amplitudes and vibration frequencies were studied using dynamic triaxial tests. Particle discrete element software was employed to study the deformation characteristics of coral sand with different particle sizes and porosities under aircraft loads. Results show that when the dynamic stress amplitude and vibration frequency were small, the pore water pressure and strain of the coral sand samples gradually increased with the number of load cycles, and the growth rate became increasingly small. When the dynamic stress amplitude and vibration frequency were large, the axial strain of the coral sand samples increased with the vibration frequency, and the growth rate exhibited an increasing trend. The deformation of the coral sand samples increased with porosity under aircraft loading. The larger the variation range of the coral sand particle size was, the larger the coral sand deformation caused by aircraft takeoff and landing load was. These results can provide a reference for the treatment and repair of the airstrip foundation of island airports.

Fast Uncooled Mid-Wavelength Infrared Photodetectors with Heterostructures of van der Waals on Epitaxial HgCdTe.

Uncooled infrared photodetectors have evoked widespread interest in basic research and military manufacturing because of their low-cost, compact detection systems. However, existing uncooled infrared photodetectors utilize the photothermoelectric effect of infrared radiation operating at 8-12 µm, with a slow response time in the millisecond range. Hence, the exploration of new uncooled mid-wavelength infrared (MWIR) heterostructures is conducive to the development of ultrafast and high-performance nano-optoelectronics. This study explores a van der Waals heterojunction on epitaxial HgCdTe (vdWs-on-MCT) as an uncooled MWIR photodetector, which achieves fast response as well as high detectivity for spectral blackbody detection. Specifically, the vdWs-on-MCT photodetector has a fast response time of 13 ns (77 MHz), which is approximately an order of magnitude faster than commercial uncooled MCT photovoltaic photodetectors. Importantly, the device exhibits a photoresponsivity of 2.5 A W-1 , quantum efficiency as high as 85%, peak detectivity of 2 × 1010  cm Hz1/2 W-1 under blackbody radiation at room temperature, and peak detectivity of up to 1011  cm Hz1/2 W-1 at 77 K. Thereby, this work facilitates the effective design of high-speed and high-performance heterojunction uncooled MWIR photodetectors.

Association of particulate matter air pollution and hospital visits for respiratory diseases: a time-series study from China.

Fine particulate matter (PM2.5) is a mixture of multiple components, which is associated with several chronic diseases, including respiratory and cardiovascular diseases. We evaluated the association between daily PM2.5 and PM2.5-10 exposure and hospital visits for respiratory diseases. Hospital visits for respiratory diseases were collected from Yinzhou Health Information System database. We used generalized additive models to examine the excess relative risk (ERR) and 95% confidence interval for hospital visits for respiratory diseases associated with each 10-µg/m3 increase in PM2.5 and PM2.5-10 concentration. Non-linear exposure-response relationship between PM exposure and hospital visits for respiratory diseases was evaluated by a smooth spline. The ERRs for hospital visits for respiratory diseases associated with a 10-µg/m3 increase in the 6-day cumulative average concentration of PM2.5 and PM2.5-10 were 5.40 (95% CI 2.32, 8.57) and 6.37% (95% CI 1.84, 11.10), respectively. The findings remained stable when we adjusted other gaseous air pollution. PM2.5 and PM2.5-10 were associated with the increased visits for the acute upper respiratory infection, pneumonia, asthma, and COPD. In this time-series study, we found a positive association between daily particulate matter exposure and hospital visits for respiratory diseases.

Acute effect of fine and coarse particular matter on cardiovascular visits in Ningbo, China.

Although a growing number of epidemiological studies have been conducted on size-specific health effects of particulate matter in China, results remain inconsistent. In this study, we investigated acute effect of fine and coarse particular matter on cardiovascular hospital visits in Ningbo, China. We used generalized additive models to examine short-term effects of PM2.5 and PM10-2.5 on cardiovascular hospital visits by adjustment for temporal, seasonal, and meteorological effects. Subgroup analyses were conducted by age, sex, and season. We also examined the stability of their effects in multi-pollutant models. We found that PM2.5 were associated with cardiovascular hospital visits (RR = 1.006; 95% CI 1.000, 1.011) and results remained similar after adjustment for PM10-2.5 (RR = 1.005; 95% CI 0.998, 1.013). There was a borderline association between PM10-2.5 and cardiovascular hospital visits (RR = 1.007; 95% CI 0.997, 1.016), which disappeared after controlling for PM2.5 (RR = 1.000; 95% CI 0.988, 1.013). The associations appeared to be stronger in the cold season and among the elderly (≥ 75 years). The findings of this study suggested significant adverse effects of PM2.5, but no independent effects of PM10-2.5 on cardiovascular hospital visits. Additional studies are needed to confirm these findings.

Association of PM2.5 pollution with the pattern of human activity: A case study of a developed city in eastern China.

Recently, air pollution has attracted a substantial amount of attention in China, which can be influenced by a variety of factors, but the association between air pollution and human activity is not quite clear. Based on real-time online data (January 1, 2014, to December 31, 2014) of air pollution and meteorology reported by official sites, and demographic, economic, and environmental reform data in a statistical yearbook, the influences of meteorological factors (temperature, relative humidity, precipitation intensity, and wind force) and human activities on PM2.5 pollution were explored. After correlation analysis, logistic regression analysis, and a nonparametric test, weak negative correlations between temperature and PM2.5 pollution were found. In most cases, festival and morning peak hours were protection and risk factors of PM2.5 pollution, respectively. In addition, government actions, such as an afforestation project and increasing financial expenditure for energy saving and environmental protection, could greatly contribute to alleviating pollution of PM2.5. The findings could help officials formulate effective laws and regulations, and then PM2.5 pollution related to the pattern of human activity would be ameliorated. IMPLICATIONS: Most of the time, festival and morning peak hours are protection and risk factors for PM2.5 pollution, respectively. Increasing the percentage of afforestation area and financial expenditure for energy saving and environmental protection could significantly reduce PM2.5 pollution. The findings can help officials formulate effective laws and regulations, and then PM2.5 pollution related to the pattern of human activity, especially government action, will be ameliorated.

Body Mass Index and Mortality: A 10-Year Prospective Study in China.

Although several studies have evaluated the role of body weight as a risk factor for mortality, most studies have been conducted in Western populations and the findings remain controversial. We performed a prospective study to examine the association between body mass index (BMI) and all-cause mortality in Yinzhou District, Ningbo, China. At baseline, 384,533 subjects were recruited through the Yinzhou Health Information System between 2004 and 2009. The final analysis was restricted to 372,793 participants (178,333 men and 194,460 women) aged 18 years and older. Cox proportional hazards models were used to estimate hazard ratios(HRs) and 95% confidence intervals(CIs). We found an increased risk of all-cause mortality among individuals with BMI levels <22.5-24.9, although several groups were not statistically significant-adjusted HRs for persons with BMIs of <15.0, 15.0-17.4, 17.5-19.9, and 20.0-22.4 were 1.61(95% CI: 1.17-2.23), 1.07(0.94-1.20), 1.04(0.98-1.10), 1.06(1.02-1.11), respectively. In the upper BMI range, subjects with BMIs of 25.0-34.9 had a reduced risk of all-cause mortality. Sensitivity analyses excluding smokers, those with prevalent chronic disease or those with less than four years of follow-up did not materially alter these results. Our findings provide evidence for an inverse association of BMI and mortality in this population.

Forecasting and Analyzing the Disease Burden of Aged Population in China, Based on the 2010 Global Burden of Disease Study.

BACKGROUND: Forecasting the disease burden of the elderly will contribute to make a comprehensive assessment about physical and mental status of the elderly in China and provide a basis for reducing the negative consequences of aging society to a minimum. METHODS: This study collected data from a public database online provided by Global Burden of Disease Study 2010. Grey model GM (1, 1) was used to forecast all-cause and disease-specific rates of disability adjusted life years (DALYs) in 2015 and 2020. RESULTS: After cross-sectional and longitudinal analysis, we found that non-communicable diseases (NCDs) were still the greatest threats in the elderly, followed by injuries. As for 136 predicted causes, more than half of NCDs increased obviously with age, less than a quarter of communicable, material, neonatal, and nutritional disorders or injuries had uptrend. CONCLUSIONS: The findings display the health condition of the Chinese elderly in the future, which will provide critical information for scientific and sociological researches on preventing and reducing the risks of aging society.

A genetic variant in MiR-146a modifies digestive system cancer risk: a meta-analysis.

MicroRNAs (miRNAs) negatively regulate gene expression and act as tumor suppressors or oncogenes in oncogenesis. The association between a single nucleotide polymorphism (SNP) in miR-146a rs2910164 and susceptibility to digestive system cancers was inconsistent in previous studies. In this study, we conducted a literature search of PubMed to identify all relevant studies published before August 31, 2013. A total of 21 independent case-control studies were included in this updated meta-analysis with 9,558 cases and 10,614 controls. We found that the miR-146a rs2910164 polymorphism was significantly associated with decreased risk of digestive system cancers in an allele model (OR=0.90, 95%CI 0.87-0.94), homozygote model (OR=0.84, 95%CI 0.77-0.91), dominant model (OR=0.90, 95%CI 0.84-0.96), and recessive model (OR=0.85, 95%CI 0.79-0.91), while in a heterozygous model (OR = 0.99, 95% CI 0.89-1.11) the association showed marginal significance. Subgroup analysis by cancer site revealed decreased risk in colorectal cancer above allele model (OR=0.90, 95%CI 0.83- 0.97) and homozygote model (OR=0.85, 95%CI 0.72-1.00). Similarly, decreased cancer risk was observed when compared with allele model (OR=0.87, 95%CI 0.81-0.93) and recessive model (OR=0.81, 95%CI 0.72-0.90) in gastric cancer. When stratified by ethnicity, genotyping methods and quality score, decreased cancer risks were also observed. This current meta-analysis indicated that miR-146a rs2910164 polymorphism may decrease the susceptibility to digestive system cancers, especially in Asian populations.