[en] Some basic concepts and formulations of two repair models of survival, the incomplete repair (IR) model and the lethal-potentially lethal (LPL) model, are introduced. An IBM-PC computer program for survival curve fitting with these models was developed and applied to fit the survivals of human melanoma cells HX118 irradiated at different dose rates. Comparison was made between the repair models and two non-repair models, the multitar get-single hit model and the linear-quadratic model, in the fitting and analysis of the survival-dose curves. It was shown that either IR model or LPL model can fit a set of survival curves of different dose rates with same parameters and provide information on the repair capacity of cells. These two mathematical models could be very useful in quantitative study on the radiosensitivity and repair capacity of cells

[en] Differential cross-section data for the n-p and n-d elastic scattering (¹H(n, el), ²H(n, el)) are collected and analyzed from EXFOR library. For E_n > 20 MeV, the experimental results for both reactions are scarce with large uncertainties and discrepancies in general. For E_n ≤ 20 MeV, the experimental results lack systematicness, most of which were measured around E_n = 14 MeV even though the differential cross sections of n-p scattering in 1 keV ≤ E_n ≤ 20 MeV region are recommended as standard. Taking these facts into account, more accurate and systematic measurements are planned. The experiments will be conducted using ΔE-E detectors of the Light-charged Particle Detector Array (LPDA) system at China Spallation Neutron Source (CSNS) Back-n White Neutron Source (WNS), and simulations are carried out. Using polyethylene and deuterated polyethylene as samples, both n-p and n-d scattering reactions are simulated along with the neutron-induced ¹²C background reactions, and the 2-D spectra and the counting rates of the ΔE-E detectors are obtained. According to the simulations, the applicable neutron energy range and positions of the detectors are recommended, and the beam time for the event and background measurements is suggested.

[en] Contents: 1. Introduction 2. Experiments 3. Data analysis 4. Results 5. Conclusions

[en] Highlights: • H₂O₂ slow-releasing composite (HSRC) can substitute liquid H₂O₂ in removing blooms. • HSRC kills Microcystis aeruginosa by a super-low H₂O₂ concentration (−1). • HSRC immobilizes phosphorus in solutions as well as that from cell lysis. Hydrogen peroxide (H₂O₂) is a widely accepted algicide in controlling cyanobacterial blooms. However, this method includes two disadvantages: 1) a low H₂O₂ concentration (−1) is required; 2) H₂O₂-induced cell lysis causes phosphorus (P) contamination. To overcome the drawbacks, a H₂O₂ slow-releasing composite (HSRC) based on calcium peroxide (CaO₂) was fabricated to substitute liquid H₂O₂. According to the results, a higher CaO₂ dose increased H₂O₂ yield and releasing rate. H₂O₂ yield of 160 mg L⁻¹ CaO₂ in HSRC reached 32.9 mg L⁻¹ and its releasing rate was 0.407 h⁻¹. In addition, a higher temperature decreased H₂O₂ yield and increased H₂O₂-releasing rate. Besides, HSRC endowed with a remarkable ability to immobilize P. Higher CaO₂ dose, pH value, and temperature increased the rate of P immobilization. The highest rate was 0.185 h⁻¹, which occurred with 160 mg L⁻¹ CaO₂ in HSRC at 25 °C and pH 8.0. Toxicity assays showed that HSRC exerted sustaining oxidative stress on Microcystis aeruginosa. Accumulation of intracellular reactive oxygen species resulted in the disruption of enzymatic systems and inactivation of photosystem. Tracking the variations of cell growth and H₂O₂ concentration during HSRC treatments, it suggested that the lethal effect on Microcystis aeruginosa was achieved with a super-low H₂O₂ concentration (−1). In addition, cell lysis did not cause a sudden rise in P concentration due to the P immobilization by HSRC. Therefore, HSRC successfully offsets the drawbacks of liquid H₂O₂ in mitigating cyanobacterial blooms. It may be a novel and promising algicide that not only kills cyanobacteria but also reduces eutrophication momentarily.

[en] An improved method for processing digital signals of the Frisch-grid ionization chamber to measure the electron drift velocity is proposed, which is based on the analysis of the cathode signal and the differentiated cathode signal. This method allows the real-time measurement eliminating the influence of electron diffusion and it is suitable for working gases with electron loss from the electronegative impurities. The electron drift velocities in gas mixtures of Ar $+$ 9.86% CH₄, Ar $+$ 3.45% CO₂, (Ar $+$ 3.45% CO₂) $+$ x% O${}_2$ (x is less than 0.33), (Ar $+$ 3.45% CO₂) $+$ y% Air (y is less than 2.09) have been measured, and the results are compared with existing measurements and calculations using MAGBOLTZ-11.4 code. Meanwhile, the influences of the impurities of oxygen and nitrogen on the electron drift velocity are analyzed.

[en] The pulse shapes of the Frisch-grid ionization chamber (GIC) will be affected by the ballistic deficit and electron attachment. Theoretical derivations and experiments are carried out to clarify the impacts of the two effects on the pulse shapes of the GIC. It is found that the anode amplitude increases with the decrease of the cosine of the emitting angle under the influence of the ballistic deficit, while the anode amplitude decreases with the decrease of the cosine of the emitting angle under the influence of the electron attachment. These opposite variation trends caused by the ballistic deficit and electron attachment could cancel each other out when the attachment probability per unit time equals the inverse of the time constant of the GIC circuit, which improves the energy resolution of the GIC, although the anode amplitude is reduced. The difference of the two variation trends provides a method to judge whether the working gas of the GIC contains electronegative gases.

[en] The electron attachment is studied using a Frisch-grid ionization chamber (GIC) with different number densities of O₂ in the working gas and different reduced electric fields. The influence of the electron attachment on the cathode–anode two-dimensional amplitude spectrum of the GIC is measured and evaluated. The method of measuring the attachment probability per unit time using the GIC is established. The quantitative and systematic relationships between the attachment probability per unit time and the number density of O₂ and the reduced electric field are obtained from experiments, where the number densities of O₂ are from 0 to 2.29 $\times$ 10¹⁷ cm ⁻³ and the reduced electric fields are from 22 to 577 V/cm/bar. The three-body attachment coefficients of O₂ at different mean electron energies (₂ at different mean electron energies (2 and CO₂ are nearly the same at the same mean electron energy.

[en] We present a novel silicon microgyroscope (SMG) temperature prediction and control system in a narrow space. As the temperature of SMG is closely related to its drive mode frequency and driving voltage, a temperature prediction model can be established based on the BP neural network. The simulation results demonstrate that the established temperature prediction model can estimate the temperature in the range of −40 to 60 °C with an error of less than ±0.05 °C. Then, a temperature control system based on the combination of fuzzy logic controller and the increment PID control method is proposed. The simulation results prove that the Fuzzy-PID controller has a smaller steady state error, less rise time and better robustness than the PID controller. This is validated by experimental results that show the Fuzzy-PID control method can achieve high precision in keeping the SMG temperature stable at 55 °C with an error of less than 0.2 °C. The scale factor can be stabilized at 8.7 mV/°/s with a temperature coefficient of 33 ppm °C"−"1. ZRO (zero rate output) instability is decreased from 1.10°/s (9.5 mV) to 0.08°/s (0.7 mV) when the temperature control system is implemented over an ambient temperature range of −40 to 60 °C. (paper)

[en] Calcium peroxide (CP) has been widely applied in environmental remediation, but few studies have reported its application in controlling Microcystis blooms. To recognize its feasibility for mitigating Microcystis blooms, the properties of CP in terms of hydrogen peroxide (HP) release and phosphate removal were investigated at different CP doses, temperatures, and initial pH values. HP release kinetics followed the Higuchi model. Batch experiments conducted in this study suggested that the HP yield and release rate were positively correlated with the CP dose. Increasing temperature decreased the HP yield but accelerated the HP release rate. The phosphate removal kinetics were well simulated by the pseudo-second-order model. The batch experiments suggested that an increased CP dose enhanced the phosphate removal capacity, but it did not affect the phosphate removal rate. Moreover, increased temperature accelerated both phosphate removal capacity and rate. However, the initial pH of low-buffer-capacity solutions did not notably affect HP release and phosphate removal. According to laboratory experiments, HP released from CP could impair photosynthetic activity, resulting in Microcystis mortality. Furthermore, the reduced phosphate concentration in the solutions suggested that CP could facilitate the control of eutrophication, which directly reduced bloom formation. Hence, our results confirmed CP as a promising algicide for Microcystis bloom control, and it is worthwhile to develop novel methods for bloom mitigation based on CP.

[en] Highlights: • Investigate fire behaviors of six two-layer combustibles. • The silk and cashmere fabrics exhibit significantly effect on the burning processes. • The fire behaviors of two-layer combustibles are mainly determined by shrink rate and the properties of the surface residues. • A combustion factor β within 0.7–0.9 was proposed to simulate the burning processes. -- Abstract: Upholstered furniture usually has a typical two-layer structure with an ultra-thin surface layer. The surface layer can significantly affect the overall fire behaviors of the upholstered furniture. A series of experiments were carried out to investigate the fire behaviors of six two-layer combustibles based on a cone calorimeter. An empirical model was proposed to predict the heat release rate of two-layer combustibles. The predictions of the model are fitting quite well with experimental data. It was also known that the ignition time of the two-layer combustis dbles is controlled by those surface fabric materials. The shrink rate and the properties of the residues of those surface fabrics show obvious influences on the combustion processes. Comparing to those uncovered natural latex foam samples, it was known that the peak heat release rate decreases about 26.9% and 11.7% for the samples with natural and synthetic species covers, respectively; and the duration of the burning process increases about 41.7% and 15.4%, respectively. A combustion factor was proposed and a heat transfer model was developed to reflect the contribution of the surface and the second layers to the combustion processes. The combustion factor is within 0.7-0.9 for the six types of surface fabrics.