Search

Biochar application for the remediation of cadmium (Cd)-contaminated soils may result in a relative deficiency of phosphorus (P) due to the disruption of soil nutrient balance. However, the P acquisition strategies of plants in such situation are still unclear. In this study, analyses on soil zymography and root morphology were combined for the first time to investigate the effects of pristine and P-modified biochars from apple tree branches on the P acquisition strategies of wheat under Cd stress. The results show that the application of pristine biochar exacerbated the soil's relative P deficiency. Wheat was forced to improve foraging for P by forming longer and thinner roots (average diameter 0.284 mm) as well as releasing more phosphatase to promote P mobilization in the soil. Moreover, bioavailable Cd affected the P acquisition strategies of wheat through stimulating the release of phosphatase from roots. The P-modified biochar maintained high levels of Olsen-P (100 mg kg

Positive-intrinsic-negative diode (PIN), avalanche photodiode (APD), and single photon avalanche diode (SPAD) are commonly used optoelectronic receivers with different characteristics in practical visible light communication system. To determine the most appropriate candidate, different signal and ambient light strength in the communication scenarios should be taken into account. APD and SPAD receivers have higher sensitivities than PIN, but there are still some defects that restrain their operation performance. APD receiver may generate excessive shot noise, whereas SPAD is limited by the dead time, afterpulsing, and smaller detection area. We initially analyze the noise characteristics of PIN, APD, and SPAD receivers. SNR models are established, and the main factors affecting the performance of APD and SPAD receivers are concluded. Then, the comparison experiments of three kinds of receivers in various transmission distances are conducted, respectively. Finally, the experimental results show that: short and mid distance conditions, PIN and APD are better choices, whereas SPAD performs better in long-distance communication. In addition, if a certain intensity of ambient light is introduced, APD is still better than SPAD even in long distance.

Oil and gas production from unconventional reservoir has grown dramatically in recent years, especially in shale reservoir. However, the conventional hydrodynamic approaches are not sufficient to describe the fluid occurrence state and flow in shale reservoir due to its widely distributed nano/mesopores and various mineral types. The effect of water on oil adsorption and transport in shale nanopores is unclear. Understanding the fluid adsorption and transport behavior in shale nanopores is essential for shale oil development. In this study, equilibrium molecular dynamics (EMD) simulation method is utilized to investigate the single phase oil and oil-water two phase adsorption behavior in clay mineral nanopores of shale. The pressure driven flow is simulated based on nonequilibrium molecular dynamics (NEMD) to investigate the fluid transport. The results show the slip boundary condition between single phase oil and surface, which leads to the breakdown of Darcy’s law for oil flow. Water has preferential adsorption on the clay mineral surface and oil presents in the middle of the nanopore, forming a layered structure. The existence of water reduced the oil adsorption and self-diffusivity in montmorillonite nanopores. For water-oil two phase flow, when oil-surface interaction completely shielded by water film, Darcy’s law still feasible for oil. Water enhanced the flow of oil in MMT nanopore due to a decrease in the friction of oil with the surface. This work advances the understanding of water effects on oil flow in confined shale nanopores, which provides the theoretical support on enhancing shale oil production.

Summary Background The outbreak of COVID-19 has led to international concern. We aimed to establish an effective screening strategy in Shanghai, China, to aid early identification of patients with COVID-19. Methods We did a multicentre, observational cohort study in fever clinics of 25 hospitals in 16 districts of Shanghai. All patients visiting the clinics within the study period were included. A strategy for COVID-19 screening was presented and then suspected cases were monitored and analysed until they were confirmed as cases or excluded. Logistic regression was used to determine the risk factors of COVID-19. Findings We enrolled patients visiting fever clinics from Jan 17 to Feb 16, 2020. Among 53 617 patients visiting fever clinics, 1004 (1·9%) were considered as suspected cases, with 188 (0·4% of all patients, 18·7% of suspected cases) eventually diagnosed as confirmed cases. 154 patients with missing data were excluded from the analysis. Exposure history (odds ratio [OR] 4·16, 95% CI 2·74–6·33; p

Background: The outbreak of novel coronavirus disease 2019 (COVID-19) has led to increasing international concern. Effective screening strategy and early recognition of the disease are crucial to limiting spread of this worldwide challenge. Methods: Fever clinics of 25 hospitals evenly distributed in 16 Districts of Shanghai were selected. All patients visiting the fever clinics from the begin of the outbreak of Shanghai (17 January 2020) to 16 February were enrolled. A standardized procedure for COVID-19 screening was presented and all the suspected cases were monitored and analyzed till they were confirmed or excluded. Findings: Among 53617 patients who visiting fever clinics, 1004 (1·87%) were considered as suspected cases, with 188 (0·35% of all patients, 18·73% of suspected cases) diagnosed as confirmed cases finally. Compared with the excluded cases, confirmed cases were older and the highest temperatures were relatively lower (p

Dissolving microneedles (DMNs) prepared from soluble polymers has been being widely investigated as a safe and effective transdermal delivery system for drug and vaccine. Limited by the materials, the air humidity would probably affect the mechanical property of DMNs, which is essential for the effective needle insertions and drug delivery. In this study, four kinds DMNs prepared by polyvinyl alcohol, sodium hyaluronate (HA), chitosan and gelatin are studied on the mechanical strength and insertion ability under varying humidity conditions. Based on these investigations, we hope to provide the effective time of DMNs to ensure a successful insertion and drug delivery.

The compatibility of an amphiphilic pH-sensitive polymer (docosahexaenoic acid–histidine–lysine, DHA–HisXLys10) and hydrophobic drug (doxorubicin, DOX) was investigated using multiscale simulations at different pH conditions, including Blends and dissipative particle dynamics simulations. Some important elements obtained from the computer simulations were analyzed, such as Flory–Huggins interaction parameters, binding energy distributions, phase diagrams and radius distribution function. In conclusion, the pH values and the number of pH-sensitive segments (histidine) significantly influence the compatibility of DHA–HisXLys10 and DOX, resulting in different drug loading capacity and system structural stability. According to the simulation results, the compatibility of the systems at pH > 6.0 is better than that at pH 6.0. Using DPD simulation, the compatibility of DHA–HisXLys10 (X = 10 or 15) and DOX is optimal when the pH is higher than 6.0, which falls in line with the results obtained from Blends simulation. Overall, when the number of histidine residues is 10 or 15 and the pH is larger than 6.0, DOX and DHA–HisXLys10 have better compatibility. So it is obvious that polymeric micelles self-assembled from DHA–His10Lys10/DHA–His15Lys10 as an ideal drug carrier have higher drug-loading capacity and more excellent stability. This work has demonstrated that multiscale simulations could be a powerful method to investigate the compatibility between polymers and drugs.

Computational fluid dynamics (CFD) software was used to simulate the internal flow field of an example muffler, and compared the results with the experimental data, verifying the reliability of the simulation algorithm. On this basis, changed the example muffler structure, researched the pressure loss of muffler which was influenced by the insert duct, the position of the baffle and the inlet air velocity. The corresponding regularities have been obtained with the results of computations, which provide a basis for the design of the muffler.