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The content of trace impurities, such as interstitial oxygen and substitutional carbon, in silicon is crucial in determining the mechanical and physical characteristics of silicon wafers. The traditional infrared (IR) method is adopted as a normal means to analyse their concentration at home and abroad, but there are two problems. The first problem is the poor representativeness of a single local sampling point because the impurity distribution in a solid sample is not as uniform as that in a liquid sample. The second problem is that interference fringes appear in the infrared spectra of the sample due to the thin wafer (≤ 300 μm thick). Based on this, controversial issues existed regarding the measured trace impurity concentrations between wafer manufacturers and solar cell assembly businessmen who used silicon sheets made by the former. Therefore, multiple transmission-reflection (MTR) infrared (IR) spectroscopy was proposed to solve the problems mentioned above. In the MTR setup, because light passes through different parts of the silicon chip several times, multiple sampling points make the final result more representative. Moreover, the optical path is lengthened, and the corresponding absorbance is enhanced. In addition to amplification of weak signals, the MTR-IR method can eliminate interference fringes via the integrating sphere effect of its special configuration. The signal-to-noise ratio of the corresponding spectrum is considerably improved due to the aforementioned dual effects. Thus, the accuracy and sensitivity of the detection method for trace impurities in silicon chips are greatly increased. In this study, silicon wafers were placed in the MTR setup, and then, their relative properties at room temperature were investigated. The corresponding theoretical calculation and simulation of infrared spectra of silicon chips were provided. This affords an optional method for the semiconductor material industry to analyse trace impurities in their chips.

There were many phosphorus chemical enterprises and phosphogypsum slag fields in the Fuquan section of the Chong-an River in the Guizhou Province of China; therefore, the dissolved phosphorus in the Fengshanqiaobian water quality monitoring section of the area has exceeded 0.2 mg/L for a long time. This study analyzed the monitoring data of dissolved phosphorus, fluoride, nitrate–nitrogen, and chemical oxygen demand in the main stream and key tributaries of the Fuquan section of the Chong-an River from 2015 to 2021, in which the main exceeding factor was dissolved phosphorus of more than 0.2 mg/L; determined the variation law of phosphorus pollution in the water body of the Fuquan section of the Chong-an River, in which the exceedance of phosphorus was mainly concentrated in May of flood season and in January and March of the drought season; evaluated the sources of phosphorus pollution, in which the main pollution sources were from phosphogypsum slag field leakage, phosphorus chemical industry plant leakage, agricultural nonpoint source pollution; and presented measures to reduce phosphorus pollutants in rivers, such as strengthening phosphogypsum slag field and phosphorus chemical enterprise seepage prevention measures, and reducing the amount of phosphate fertilizer application.

The prediction of river runoff is crucial for flood forecasting, agricultural irrigation and hydroelectric power generation. A coupled runoff prediction model based on the Gravitational Search Algorithm (GSA) and the Seasonal Autoregressive Integrated Moving Average (SARIMA) model is proposed to address the non-linear and seasonal features of runoff data. The GSA has a significant local optimisation capability, while the SARIMA model allows for real-time adjustment of the model using historical data and is suitable for analysing time series with seasonal variations. Consequently, the GSA-SARIMA model was developed and applied to the runoff prediction of the Xianyang section of the Wei River. The results suggest that the GSA-SARIMA model achieves a linear correlation coefficient of 0.9351, a Nash efficiency coefficient of 0.91, a mean relative error of 6.57 and a root mean square error of 0.21. All of the evaluation indicators of this model outperform the other models developed, and its application to actual runoff prediction is feasible, which creates a new path for runoff prediction. HIGHLIGHTS The Mann-Kendall trend test is applied to ascertain the separation point between the training and prediction datasets. It avoids too little data in the test set, while effectively improving the generalisation of the model. The SARIMA model is an improvement on the ARIMA model and allows for convenient real-time adjustment of the model. The GSA algorithm is applicable to parameter search optimization of the model and has great global search capability.

In this protocol we describe a method to obtain telomere length parameters using Southern blots of terminal restriction fragments (TRFs). We use this approach primarily for epidemiological studies that examine leukocyte telomere length. However, the method can be adapted for telomere length measurements in other cells whose telomere lengths are within its detection boundaries. After extraction, DNA is inspected for integrity, digested, resolved by gel electrophoresis, transferred to a membrane, hybridized with labeled probes and exposed to X-ray film using chemiluminescence. Although precise and highly accurate, the method requires a considerable amount of DNA (3 μg per sample) and it measures both the canonical and noncanonical components of telomeres. The method also provides parameters of telomere length distribution in each DNA sample, which are useful in answering questions beyond those focusing on the mean length of telomeres in a given sample. A skilled technician can measure TRF length in ∼130 samples per week.

Monitoring the degradation of the dynamic elastic modulus (Ed) of concrete is of great importance to track the durability deterioration for hydraulic concrete structures. For the aqueduct under investigation in this study, the dynamic elastic modulus of bent frames and moment frame supports (Ed-frame), the dynamic elastic modulus of arch trusses (Ed-arch) and the shear stiffnesses of the asphaltic bearings of U-shaped flumes (Kflume) are the main parameters to define the dynamic behavior of the structure, which have direct correlation with its vibrational characteristics and thus practicably can be estimated by a BP (back-propagation) neural network using modal frequencies as inputs. Since it is impossible to obtain sufficient experimental field data to train the network, a full-scale 3D FE model of the entire aqueduct is created, and modal analyses under different combinations of Kflume, Ed-arch and Ed-frame are conducted to generate the analytical dataset for the network. After the network’s architecture is refined by the cross-validation process and its modeling accuracy verified by the test procedure, the primary modal frequencies of the aqueduct obtained from in situ dynamic tests are put into the network to obtain the final approximations for Kflume, Ed-arch and Ed-frame, which sets an evaluation baseline of the general concrete Ed status for the aqueduct and indicates that the makeshift asphaltic bearings of U-shaped flumes basically can be treated as a three-directional hinge in the FE model. It is also found that more inputs of modal frequencies can improve the prediction accuracy of the BP neural network.

This study presents part of a pilot work for the structural health monitoring of a large tied-arch reinforced concrete aqueduct in eastern China. Based on field-monitored data for over a year, it mainly focuses on the effect of air temperature and water load variations on the static behavior of a typical span of the aqueduct through field monitoring and 3D FE model analysis. It is found that the longitudinal deformation of the composite tied-arch shows a good linear relationship with the air temperature during the non-operation period and also has a good bilinear correlation with the air temperature and water level during operation. However, isolation of the air temperature effect from the second bilinear correlation using the first linear relationship results in a poor correlation between the longitudinal deformation and water level due to the dominance of the temperature effect. Therefore, it is recommended to use the bilinear regression to predict the longitudinal deformation of the tied-arch during operation. The vertical deformation of the tied-arch is insignificantly affected by air temperature, whereas it shows a fair bilinear correlation with the air temperature and water level during operation, which can be used to provide a reasonable estimation of the vertical deformation of the tied-arch. The strain measurements of the tied-arch using vibrating-string gauges are more complicated due to the notable influence of the ambient temperature and solar radiation, but the relatively consistent bilinear regression of the strains versus the air temperature and water level can still give fair predictions for the strains of the bottom tension rods during operation. The 3D FE model can provide a fair estimation for the vertical deformation of the tied-arch under water load, but its predictions for longitudinal deformation and strains are less satisfactory when compared to monitored data excluding temperature effects.

We report findings from a clinical evaluation of lentiviral vectors in a phase I open-label nonrandomized clinical trial for HIV. This trial evaluated the safety of a conditionally replicating HIV-1-derived vector expressing an antisense gene against the HIV envelope. Five subjects with chronic HIV infection who had failed to respond to at least two antiviral regimens were enrolled. A single i.v. infusion of gene-modified autologous CD4 T cells was well tolerated in all patients. Viral loads were stable, and one subject exhibited a sustained decrease in viral load. CD4 counts remained steady or increased in four subjects, and sustained gene transfer was observed. Selflimiting mobilization of the vector was observed in four of five patients. There is no evidence for insertional mutagenesis after 21-36 months of observation. Immune function improved in four subjects. Lentiviral vectors appear promising for gene transfer to humans.

The shape of bridge piers across rivers is one of the significant factors that affect the backwater in the river. The study on the influence of bridge pier shapes on the flow patterns of the river is valuable to the design of the bridge and river flooding. Based on the MIKE21 Flow Model hydrodynamic model, dynamic numerical simulations were conducted to investigate the effect of different shapes of bridge piers on water flow. The result shows that rectangular, circular and elliptical piers have a water blocking effect on the river. The flow patterns changed in local areas near the piers. Under the same flow rate, the backwater of the rectangular pier was the largest, followed by the circular piers, and the elliptical pier was the smallest. The value of backwater volume caused by the rectangular pier was 1.95 times the elliptical pier. The elliptical bridge piers basically do not change the overall flow patterns of the river, and have little effect on the river regime. This work provides a reference for the layout of river bridge piers.

Telomeres are engaged in a host of cellular functions, and their length is regulated by multiple genes. Telomere shortening, in the course of somatic cell replication, ultimately leads to replicative senescence. In humans, rare mutations in genes that regulate telomere length have been identified in monogenic diseases such as dyskeratosis congenita and idiopathic pulmonary fibrosis, which are associated with shortened leukocyte telomere length (LTL) and increased risk for aplastic anemia. Shortened LTL is observed in a host of aging-related complex genetic diseases and is associated with diminished survival in the elderly. We report results of a genome-wide association study of LTL in a consortium of four observational studies (n = 3,417 participants with LTL and genome-wide genotyping). SNPs in the regions of the oligonucleotide/oligosaccharide-binding folds containing one gene (OBFC1; rs4387287; P = 3.9 x 10⁻⁹) and chemokine (C-X-C motif) receptor 4 gene (CXCR4; rs4452212; P = 2.9 x 10⁻⁸) were associated with LTL at a genome-wide significance level (P < 5 x 10⁻⁸). We attempted replication of the top SNPs at these loci through de novo genotyping of 1,893 additional individuals and in silico lookup in another observational study (n = 2,876), and we confirmed the association findings for OBFC1 but not CXCR4. In addition, we confirmed the telomerase RNA component (TERC) as a gene associated with LTL (P = 1.1 x 10⁻⁵). The identification of OBFC1 through genome-wide association as a locus for interindividual variation in LTL in the general population advances the understanding of telomere biology in humans and may provide insights into aging-related disorders linked to altered LTL dynamics.

Wastewater generated in the production of phosphorus flame retardants contains benzene, xylene, acetophenone, and 9, 10-dihydro-9-oxa-10-phosphoxanthine-10-oxide (DOPO) with larger benzene rings, which are more difficult to biodegrade directly. In this study, the wastewater generated in the production of phosphorus flame retardants applied for high-temperature nylon and reactive phosphorus flame retardant was first treated by the combined process of lime emulsion–flocculation reaction and precipitation–ozone oxidation reaction for degradation of benzene, xylene, acetophenone, and DOPO, and then processed by the secondary combined process of upflow anaerobic sludge bed anaerobic digestion–air flotation–membrane bioreactor bio-contact oxidation; thus, the final concentration of pollutants in the wastewater can reach the relevant limit either for external discharge or as the supplemental water for other production devices. In addition, the detailed chemical degradation mechanisms and removal effects of benzene, xylene, acetophenone, and DOPO in an ozone reactor were explored. After the project had been normally operated for half a year, the test results of the effluent were as follows: chemical oxygen demand, 50 mg/L; BOD5, 20 mg/L; NH3-N, 5.0 mg/L; total phosphorus, 0.5 mg/L; benzene ≤ 0.1 mg/L; xylene ≤ 0.4 mg/L; acetophenone ≤ 0.4 mg/L; and DOPO ≤ 0.02 mg/L. Ultimately, the cost was 2.1 $/m3. It provides a useful process for wastewater treatment related to phosphorus flame retardants.