Purpose With the increasing awareness of global warming and the important role of last mile distribution in logistics activities, the purpose of this paper is to build an environmental and effective last mile distribution model considering fuel consumption and greenhouse gas emission, vehicle capacity and two practical delivery service options: home delivery (HD) and pickup site service (PS). This paper calls the problem as the capacitated pollution-routing problem with pickup and delivery (CPRPPD). The goal is to find an optimal route to minimize operational and environmental costs, as well as a set of optimal speeds over each arc, while respecting capacity constraints of vehicles and pickup sites.
Design/methodology/approach To solve this problem, this research proposes a two-phase heuristic algorithm by combining a hybrid ant colony optimization (HACO) in the first stage and a multiple population genetic algorithm in the second stage. First, the HACO is presented to find the minimal route solution and reduce distribution cost based on optimizing the speed over each arc.
Findings To verify the proposed CPRPPD model and algorithm, a real-world instance is conducted. Comparing with the scenario including HD service only, the scenario including both HD and PS option is more economical, which indicates that the CPRPPD model is more efficient. Besides, the results of speed optimization are significantly better than before.
Practical implications The developed CPRPPD model not only minimizes delivery time and reduces the total emission cost, but also helps logistics enterprises to establish a more complete distribution system and increases customer satisfaction. The model and algorithm of this paper provide optimal support for the actual distribution activities of logistics enterprises in low-carbon environment, and also provide reference for the government to formulate energy-saving and emission reduction policies.
Originality/value This paper provides a great space for the improvement of carbon emissions in the last mile distribution. The results show that the distribution arrangement including HD and PS services in the last mile adopting speed optimization can significantly reduce the carbon emission. Additionally, an integrated real-world instance is applied in this paper to illustrate the validity of the model and the effectiveness of this method.
Purpose The purpose of this paper is to monitor the environmental efficiency of suppliers in the presence of undesirable output and dual-role factors with static and dynamic aspects. Meanwhile, it also aims to explain the main reason for the low efficiency of suppliers.
Design/methodology/approach The authors propose a modified data model considering undesirable output and dual-role factors. The study integrates the modified data envelopment analysis model into the distance function of the Malmquist–Luenberger index. Moreover, this study uses the global benchmark technology to formulate a two-stage model. To verify the validity of this model, a model application is conducted on an automotive spare components company in China.
Findings The results identify the unique status of dual-role factors based on the global optimality of the model and then categorize inefficient suppliers in an individual evaluation cycle. In addition, each supplier is projected on a frontier curve after obtaining the improved data. Furthermore, through the status plot of M-L and its components, this paper concludes that efficiency scale change is the main reason for the gap in ecological performance between different suppliers.
Research limitations/implications The proposed model considers both undesirable output and dual-role factors; however, variables with different features, such as imprecise, fuzzy and qualitative characteristics, can be embedded into the presented two-stage model.
Originality/value Evaluating green suppliers through multiple consecutive evaluation cycles will aid a company in effectively managing its key suppliers. Furthermore, the evaluation provides policy guidance for further improvement of suppliers.
Jinman Zhong,1,* Jianke Ding,2,* Lei Deng,1 Ying Xiang,1 Duoduo Liu,1 Yanyan Zhang,1 Xin Chen,1 Quanxin Yang1 1Department of Radiology, The Second Affiliated Hospital, Xi' an Jiaotong University, Xi'an, Shaanxi Province, 710004, People's Republic of China; 2Department of Plastic and Reconstructive Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi Province, 710032, People's Republic of China*These authors contributed equally to this workCorrespondence: Quanxin Yang; Xin ChenDepartment of Radiology, The Second Affiliated Hospital, Xi' an Jiaotong University, 157 Xiwu Road, Xi'an, Shaanxi Province, 710004, People's Republic of ChinaEmail quanxin1962@163.com; chen_x129@163.comBackground: The sensitive and specific detection of pathogenic cells is important in tumor diagnosis at an early stage. Aptamers are short single-stranded oligonucleotides evolved from systematic evolution of ligands by exponential enrichment (SELEX). It has been proved that aptamers can interact with cognate target molecules with high affinity and specificity and have great potential in the development of medical imaging at molecular level.Purpose: To select epithelial cell adhesion molecule (EpCAM) specific aptamers targeting prostate cancer and further to conjugate aptamers with GoldMag nanoparticles (a typical iron oxide core/gold shell structure) to construct magnetic molecular probes for medical imaging.Methods: EpCAM-specific aptamers were selected by Cell-SELEX. The enrichment of specific aptamer candidates was monitored by flow cytometric analysis. Aptamers were further conjugated with GoldMag nanoparticles to construct magnetic molecular probes. The affinity and specificity of aptamer candidates and aptamer-conjugated GoldMag nanoparticles were evaluated. The MR imaging of aptamer-conjugated GoldMag nanoparticles to prostate cancer was further explored in vitro and in vivo.Results: After 12 rounds of selection, aptamer candidates Eppc6 and Eppc14 could specifically target three types of prostate cancer cells, revealing a high affinity of Eppc6 and Eppc14. Moreover, aptamer-conjugated GoldMag nanoparticles not only exhibited good affinity to different prostate cancer cells but also produced strong T2WI signal intensity reduction distinguished from peritumoral tissue in MRI, indicating that the molecular probes possess both the affinity properties of EpCAM-specific aptamer and the superparamagnetic features of iron oxide.Conclusion: Our study indicates that aptamer Eppc6 and Eppc14 can recognize prostate cancer cells and tissues. The aptamer-conjugated GoldMag nanoparticles constructed in the study can be used as a molecular imaging agent for detection of PCa in MRI.Keywords: EpCAM, aptamer, Cell-SELEX, prostate cancer
The transport of eroded soil to rivers changes the nutrient cycles of river ecosystems and has significant impacts on the regional eco-environment and human health. The Loess Plateau, a leading vegetation restoration region in China and the world, has experienced severe soil erosion and nutrient loss, however, the extent to which vegetation restoration prevents soil erosion export (to rivers) and it caused nutrient loss is unknown. To evaluate the effects of the first stage of the Grain for Green Project (GFGP) on the Loess Plateau (started in 1999 and ended in 2013), we analyzed the vegetation change trends and quantified the effects of GFGP on soil erosion export (to rivers) and it caused nutrient loss by considering soil erosion processes. The results were as follows: (1) in the first half of study period (from 1982 to 1998), the vegetation cover changed little, but after the implementation of the first stage of the GFGP (from 1999 to 2013), the vegetation cover of 75.0% of the study area showed a significant increase; (2) The proportion of eroded areas decreased from 41.8 to 26.7% as a result of the GFGP, and the erosion intensity lessened in most regions; the implementation significantly reduce the soil nutrient loss; (3) at the county level, soil erosion export could be avoided significantly by the increasing of vegetation greenness in the study area (R = −0.49). These results illustrate the relationships among changes in vegetation cover, soil erosion and nutrient export, which could provide a reference for local government for making ecology-relative policies.
Lei Deng,1,2 Xiaoli Pan,1 Yulong Zhang,1 Sujing Sun,1 Liping Lv,1 Lei Gao,1 Ping Ma,1 Huisheng Ai,2 Qianqian Zhou,1 Xiaohui Wang,1 Linsheng Zhan1 1Department of Emerging Transfusion Technology, Institute of Health Service and Transfusion Medicine, Academy of Military Medical Sciences, Beijing, People's Republic of China; 2Department of Hematology, The Fifth Medical Center of Chinese PLA General Hospital, Beijing, People's Republic of ChinaCorrespondence: Xiaohui Wang; Linsheng ZhanDepartment of Emerging Transfusion Technology, Institute of Health Service and Transfusion Medicine, Academy of Military Medical Sciences, Beijing, People's Republic of ChinaEmail lszhan91@yahoo.com; lovechina1980@163.comBackground: Due to their extraordinary physical and chemical properties, MoS2 nanosheets (MSNs) are becoming more widely used in nanomedicine. However, their influence on immune systems remains unclear.Materials and Methods: Two few-layered MSNs at sizes of 100– 250 nm (S-MSNs) and 400– 500 nm (L-MSNs) were used in this study. Bone marrow-derived dendritic cells (DCs) were exposed to both MSNs at different doses (0, 8, 16, 32, 64, 128 μg/mL) for 48 h and subjected to analyses of surface marker expression, cytokine secretion, lymphoid homing and in vivo T cell priming.Results: Different-sized MSNs of all doses did not affect the viability of DCs. The expression of CD40, CD80, CD86 and CCR7 was significantly higher on both S-MSN- and L-MSN-treated DCs at a dose of 128 μg/mL. As the dose of MSN increased, the secretion of IL-12p70 remained unchanged, the secretion of IL-1β decreased, and the production of TNF-α increased. A significant increase in IL-6 was observed in the 128 μg/mL L-MSN-treated DCs. In particular, MSN treatment dramatically improved the ex vivo movement and in vivo homing ability of both the local resident and blood circulating DCs. Furthermore, the cytoskeleton rearrangement regulated by ROS elevation was responsible for the enhanced homing ability of the MSNs. More robust CD4+ and CD8+ T cell proliferation and activation (characterized by high expression of CD107a, CD69 and ICOS) was observed in mice vaccinated with MSN-treated DCs. Importantly, exposure to MSNs did not interrupt LPS-induced DC activation, homing and T cell priming.Conclusion: Few-layered MSNs ranging from 100 to 500 nm in size could play an immunostimulatory role in enhancing DC maturation, migration and T cell elicitation, making them a good candidate for vaccine adjuvants. Investigation of this study will not only expand the applications of MSNs and other new transition metal dichalcogenides (TMDCs) but also shed light on the in vivo immune-risk evaluation of MSN-based nanomaterials.Keywords: MoS2 nanosheets, dendritic cells, migration, vaccine adjuvant
