Modeling and efficiency analysis of blockchain agriculture products E-commerce cold chain traceability system based on Petri net.

The cold chain supply chain of e-commerce has the characteristics of long chain, dispersed production, heterogeneous information sources, etc., which is easy to cause the upstream and downstream information of the supply chain to be broken and opaque. Traditional traceability data is stored in each node enterprise, and there are problems such as low cooperation trust and poor authenticity in the upstream and downstream data transmission process of the supply chain, resulting in consumers' trust crisis on the authenticity of traceability information. Blockchain traceability system through the establishment of multi-party participation, joint maintenance of distributed database, and the use of cryptography and consensus mechanism to establish trust relationships, with data can not be tampered with, sharing of high credibility. On the basis of stochastic Petri net theory, this study constructed a blockchain e-commerce cold chain traceability model centering on the actual application of blockchain technology in logistics traceability to improve the reliability and validity of e-commerce cold chain traceability. Correlation matrix and invariants were used to analyze the validity of the model, and an isomorphic Markov chain was constructed to analyze the effectiveness evolution of the model. This study aims to deepen the understanding of the cold chain traceability system of blockchain e-commerce from the three aspects of the best optimization link, the best synergism scale, and the adaptive ability of the system to provide reference for the improvement of cold chain traceability ability by blockchain technology.

A one-step foraminoplasty via a large trephine in percutaneous endoscopic transforaminal discectomy for the treatment of lumbar disc herniation.

BACKGROUND: Transforaminal percutaneous endoscopic lumbar discectomy (PELD) is a widely used basic technique for lumbar disc herniation (LDH) with advantages including causing less trauma and fast recovery. The secure, efficient, and rapid enlargement of the intervertebral foramen is a key step in PELD procedures. However, the conventional multi-step trephine system for foraminoplasty involves complicated surgical procedures. In this study, we reported an improved one-step foraminoplasty via a large trephine with simplified surgical procedures, reduced radiation exposure, and shortened operative time. METHODS: 70 LDH patients who underwent PELD were retrospectively reviewed in this study. The conventional multi-step trephine system was used for foraminoplasty in 35 patients in the multi-step (MS) group, and the single large trephine was used in the other 35 patients in the one-step (OS) group. Indicators including the operative time, the time to establish the working cannula, intraoperative fluoroscopy times, the radiation dose, and postoperative complications were compared between the MS and OS group. RESULTS: The operative time and the time to establish the working cannula in the OS group was significantly shorter than that in the MS group (P < 0.01); intraoperative fluoroscopy times and the radiation dose in the OS group were significantly smaller than those in the MS group (P < 0.01). There was no statistical difference in the incidence of postoperative complications between the two groups (P > 0.05). The postoperative VAS scores and ODI scores (2 days and 3 months after the surgery) were significantly lower than the preoperative scores in both groups (P < 0.01), and there was no statistical difference in VAS scores or ODI scores between the two groups at the same time points (P > 0.05). CONCLUSIONS: The one-step foraminoplasty via a single large trephine is an optimized technique evolving from the conventional multi-step foraminoplasty, showing significant superiority in simplified operation, shorted operative time, and reduced radiation exposure.

Divergent gross nitrogen transformation paths in the topsoil and subsoil between abandoned and agricultural cultivation land in irrigated areas.

The nitrate concentration in groundwater has increased in many irrigated areas worldwide due to the excessive use of both water and fertilizers. Abandoned farmlands in such irrigated areas may alter the nitrogen (N) cycle because of drastically changed water and N inputs. However, the mechanisms of the N cycle in response to such changes remain unclear. We studied biogeochemical N cycling and microbiological responses from abandoned arable lands (AF), for the topsoil (20 cm depth) and subsoil (100 cm depth) layers, in comparison with irrigation-fertilization (control = CK) land, by using 15N tracing techniques, the 16S rRNA gene, and real-time PCR (qPCR) to reveal the mechanisms underpinning the N cycle. We found that the biogeochemical environment of abandoned soils shifted their N-cycling pathways. Except for reduced soil moisture, soil properties of total C and N, as well pH, showed improvement in the two layers of AF. But the microbial abundances of ammonia-oxidizing bacteria (AOB-amoA), archaea (AOA-amoA), bacteria and fungi were all significantly lower in the AF; and they presented a consistent trend in the subsoil of the two lands. Significant differences in gross N transformation rates were found for mineralization rates (MN) and autotrophic nitrification rate (ONH4) between lands or depths. Compared with AF, MN was increased by 1.45- and 11.75-times, and ONH4 by 1.69- and 2.89-times in the topsoil and subsoil of CK, respectively. Our results suggest that the SM × C/N interaction provides insight into the mechanisms underlying the soil microbe-driven changes to transformation rates in nitrogen dynamics after abandoning water-limited lands. The high moisture and N inputs reported here highlight the dynamics and prevalence of MN and ONH4, and an increasing the nitrate leaching rate in the unsaturated zone, which poses a major threat to groundwater quality.

The effects of irrigation and fertilization on the migration and transformation processes of main chemical components in the soil profile.

Understanding the changes in chemical composition of soil plays an important role in effective control of irrigation and fertilization in agricultural productions, which further protects the groundwater quality and predicts its evolution. Field trials were conducted from 2014 to 2016 to investigate the impacts of irrigation and fertilization on mineral composition transformation in the soil profile. Based on HYDRUS-HP1 and Visual MINTEQ, this paper simulated and computed the migration and transformation of chemical components during the irrigation and fertilization in the vadose zone soil of Jinghuiqu district. The results showed that when the nitrogen fertilizer entered the soil, the urea was hydrolyzed to NH4+ and it was nitrified as NO2-, which caused pH value to drop around the first 4 days after irrigation, and rise slightly on the 12th day. Due to the fact that soil belongs to calcareous soil, concentration of CaCO3 and other carbonates (Mg or Na in sodic soils) could buffer the soil pH well above 8.5. Thus, on the 30th day of the post-irrigation the pH reached the same level as it was before irrigation. The change in pH resulted in the main ions reacting, dissolving and precipitating simultaneously in the soil profile. The concentrations of Ca2+, Mg2+ and HCO3- had significant correlations with the increasing ammonia nitrogen hydrolyzed from urea, and this process is accompanied with the saturation index of minerals and the main ion content changing. At the same time, the varying temperature action on pH of the soil was higher in summer than that in winter. Thus, the irrigation, fertilization and temperature had affected pH and main chemical components in the soil.