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Cellulose and its derivatives are natural materials with high carbon contents, but it is challenging to convert their carbon into high value-added carbonaceous materials (e.g., graphene). Here, an approach to convert the carbon in cellulose into N, P co-doped porous graphene (LIG) materials via laser induction is proposed. Cellulose nanofibrils (CNFs), a cellulose derivative with high dispersion uniformity and abundant surface hydroxyl groups, were easily formed on a bulk substrate (thickness ≥ 5 mm) containing ammonium polyphosphate (APP). Then, a 10.6 μm CO2 laser was used to scribe for 1–5 passes on the CNFs/APP substrate under an ambient environment to produce N, P co-doped porous LIG. Upon increasing the number of laser scribing passes, the IG/ID of LIG first increased and then decreased, reaching a maximum of 1.68 at 4 passes. The good pore structure and low resistance also showed that 4 laser passes were ideal. Besides, the N, P co-doped LIG also showed excellent electrochemical performance, with a specific capacitance of 221.4 F/g and capacitance retention of 89.9%. This method exploits the advantages of nanocellulose and overcomes the difficulties associated with directly compounding cellulosic materials, providing a method for the further development of biomass nanomaterials.

To pursue excellent performance of supercapacitor, an electrode material with designed morphology and tailored intrinsic properties is indeed desired. Herein, nickel–cobalt sulfides hollow spheres decorated with rich sulfur vacancies r-NiCo2S4 HSs) are prepared via an anion exchange of Ni-Co coordination polymer spheres, combined with wet chemical reduction. The r-NiCo2S4 HSs sample delivers excellent performance as an electrode: it possesses a high specific capacity (763.5C g−1 at 1 A/g), favorable cyclability (91.40% after 5000 cycles at 10 A/g) and rate capacity (522.68C g−1 at 15 A/g). Additionally, an all-solid-state hybrid supercapacitor device, assembled with r-NiCo2S4 HSs as the positive electrode and N/S co-doped activated carbon nanosheets as the negative electrode, presents an excellent energy density of 50.76 Wh kg−1 under 800 W kg−1 and feasible stability. Thus, combining hollow structure with sulfur vacancies could not only increase more active sites and ensure sufficient redox reactions, but also enhance electronic conductivity, facilitate ions / electrons transport and shorten diffusion path, which could be regarded as a promising approach to develop electrode materials with outstanding performance.

Vessels served by a container port can usually be classified into two types: deep-sea vessels and feeders. While the arrival times and service times of deep-sea vessels are known to the port operator when berth plans are being devised, the service times of feeders are usually uncertain due to lack of data interchange between the port operator and the feeder operators. The uncertainty of feeder service times can incur long waiting lines and severe port congestion if the service plans for deep-sea vessels and feeders are poorly devised. This paper studies the problem of how to allocate berths to deep-sea vessels and schedule arrivals of feeders for congestion mitigation at a container port where the number of feeders to be served is significantly larger than the number of deep-sea vessels, and where the service times of feeders are uncertain. We develop a stochastic optimization model that determines the berth plans of deep-sea vessels and arrival schedules of feeders, so as to minimize the departure delays of deep-sea vessels and schedule displacements of feeders. The model controls port congestion through restricting the expected queue length of feeders. We develop a three-phase simulation optimization method to solve this problem. Our method comprises a global phase, a local phase, and a clean-up phase, where the simulation budget is wisely allocated to the solutions explored in different phases so that a locally optimal solution can be identified with a reasonable amount of computation effort. We evaluate the performance of the simulation optimization method using test instances generated based on the operational data of a container port in Shanghai.

Vessel pilotage is compulsory in most seaports around the world. When traveling into or out of the terminal of a seaport, vessels should be navigated by sea pilots in order to follow correct and safe waterways. This paper studies a pilotage planning problem that involves decisions of scheduling the vessel traffic in a seaport, assigning work shifts to pilots, and scheduling the pilots in each work shift for vessel navigation. We formulate the problem as a linear mixed-integer programming (MIP) model that aims at minimizing the cost incurred by the pilotage operations, and show that the problem is strongly NP-hard. For solving the problem, we develop a branch-and-price (B&P) algorithm in which the pricing problem is solved by a novel dynamic programming algorithm. We further propose several acceleration techniques to improve the efficiency of the B&P algorithm. The computational performance of the B&P algorithm is evaluated in extensive numerical experiments. Computational results demonstrate that the B&P algorithm is able to solve problem instances of practical sizes, and that the algorithm outperforms a standard MIP solver and a solution method commonly used in practice.

To enhance the exploitation efficiency of natural gas hydrate by decreasing the yield of water, a novel “reservoir reformation” concept is proposed that involves the reformation of a natural gas hydrate reservoir by constructing an artificial impermeable overlying CO2 hydrate cap. The feasibility of this concept has been demonstrated in this laboratory-scale experiment. After reformation by injecting CO2 emulsion into the permeable overburden, a confined environment with an impermeable CO2 hydrate cap is successfully constructed for depressurization operation. The cap can maintain mechanical stability until the end of production process. With the protection provided by the artificial CO2 hydrate cap, the production efficiency was greatly improved to 83.3% and the water yield is remarkably decreased. Moreover, the optimal CO2/H2O volume ratio of the emulsion for forming the desired CO2 hydrate cap was confirmed to be 1:1. The formation of CO2 hydrate cap can also protect the geological stability of depleted methane hydrate zones and seal a large amount of CO2, which is of both energetic and environmental significance; however, intensive and extensive research should be conducted in the future.

In the global maritime transportation network, the on-time performance of cargo transportation depends largely on the service capacity and accessibility of seaports. When opportunities for infrastructure expansions are not available, seaport congestion mitigation may require effective scheduling of the vessel traffic in the port waters. While existing works on vessel traffic scheduling focus on minimizing vessel delays, this paper studies a novel vessel traffic scheduling problem that aims to address the inter-shipping line equity issue. We develop a parameterized lexicographic optimization model that takes into account two conflicting performance measures; namely, efficiency, which favors minimizing total vessel delay, and equity, which favors balancing the impacts of delays fairly among shipping lines. Our model allows the port operator to quantify the efficiency-equity trade-off and make the best vessel traffic scheduling decisions. For solving the model, we develop an effective two-stage solution method in which the first stage solves two single-objective models to obtain the maximum system efficiency and equity, while the second stage trades between efficiency and equity and seeks the best compromise between the two conflicting objectives. We apply our model and solution method on instances generated from the operational data of the Port of Shanghai. Our computational results show that an efficiency-oriented model can lead to highly inequitable traffic plans, while inter-shipping line equity can be achieved at only mild losses in efficiency, indicating that the consideration of inter-shipping line equity can lead to satisfactory service at both the vessel level and the shipping line level.

This paper studies an order fulfilment problem in an e-tailing environment, where the e-tailer fulfills orders by assigning orders to its fulfilment centers and routing the shipments from the fulfilment centers to its delivery stations. We develop a mixed integer program for the problem, analyze its computational complexity, and propose a Benders decomposition algorithm for solving the problem. Computational performance of the proposed algorithm is evaluated on problem instances generated based on the logistics network of JD.com in Shanghai. Computational results show that the Benders decomposition algorithm is able to achieve satisfactory performance within reasonable computation time.

Container liner shipping network alteration is a practical manner of shipping network design, which aims to make minor modifications to ameliorate the existing network. In a generic liner shipping network with butterfly ports, each ship route is separated into a set of subloops on the basis of its structure and internal butterfly ports. Reversing the subloop directions has an impact on the network-wide cost including inventory cost, transshipment cost, and slot-purchasing cost. This paper proposes a new destination-based nonlinear model for the subloop-based reversal of port rotation directions with the objective of minimizing the overall network-wide cost. We prove that the addressed problem is NP-hard. Next, the model is transformed to an equivalent mixed-integer linear programming model. Based on the structure of the reformulated model, we develop a Benders decomposition (BD) algorithm and a metaheuristic method to solve practical-size instances. Three acceleration strategies are incorporated into the BD algorithm, which are adding Pareto-optimal cuts, updating big-M coefficients and generating combinatorial Benders cuts. Case studies based on three small examples and an Asia-Europe-Oceania liner shipping network with a total of 46 ports are conducted. Results show that the problem could be efficiently solved by the accelerated BD algorithm and the optimization of subloop directions is conducive to decreasing the network-wide cost especially the inventory cost.

Corrosion has been one of the most challenging long-term problems for many industry sectors. It accounts for more than half of the industrial failures and costs tens of billion dollars every year. Hexagonal boron nitride (h-BN), a chemically inert layered two-dimensional electrical insulator, which is stable at high temperature under an ambient environment, has been considered as a promising candidate for ultrathin protective coatings especially for harsh environments. In this work, we develop an efficient chemical vapor deposition (CVD) method to directly grow high quality, uniform, and large-area continuous h-BN thin films on industry-relevant stainless-steel substrate. During growth, the h-BN crystalline triangles merge together to form a large-area, voids-free, and continuous thin film on both flat and curved surfaces of stainless-steel substrates. The as-grown h-BN thin films could protect the stainless-steel substrates from oxidization under ambient condition at 800 °C and from corrosion in an extremely corrosive solution at both room and elevated temperatures.

The aggregated lymphoid nodules area (ALNA) in the abomasum is a special organized lymphoid tissue discovered only in Bactrian camels at present. This study aimed to explore the impact of aging on distribution of IgA+ and IgG+ cells in ALNA in abomasum of Bactrian camels. Twenty-four Alashan Bactrian camels were divided into the following four age groups: young (1-2years), pubertal (3-5years), middle-aged (6-16years) and old (17-20years). IgA+ and IgG+ cells in the lamina propria of ALNA were observed and analyzed using immunohistochemical and statistical techniques. The results showed that, in ALNA, the distribution of IgA+ and IgG+ cells were diffuse, and only a few were in subepithelium dome (SED) and most of them in non-SED. Meanwhile, there were significantly more IgA+ cells than IgG+ cells in SED from the young to the middle aged group, but which reversed in old group (P

In this paper, we focus on the on-axis intensity evolutions of anomalous hollow Gaussian beams in highly nonlocal nonlinear media. It is found that the evolution of on-axis intensity is always periodic and the incident power of the beams plays a key role. By selecting the different amplitude of the incident power, the on-axis intensity evolutions exhibit themselves as three different shapes in each evolution period, i.e. the protrusion situation, the platform situation and the indentation situation. We analyze the three situations in detail, and the extreme values of on-axis intensity and their positions are all given analytically. The influences of the beam ellipticity and the off-waist departure distance on the on-axis intensity evolutions are also discussed. It is found that the evolution of on-axis intensity becomes more complicated, and the on-axis intensity evolution in each period splits into two intensity peaks. Keywords: Highly nonlocal nonlinear medium, Beam propagation, On-axis intensity

In this report, we utilize the heterostructures of monolayer MoS2 and self-assembled monolayers (SAMs) of organic molecules as a platform to understand how carrier density of nanomaterials affects their friction behaviors. Previous studies on the friction of two-dimensional materials have explored the effect of lattice structures and morphologies. Given the same normal force and scanning speed of the AFM tip, we observe the sliding friction of high-quality n-type monolayer MoS2 could be reduced by SAMs. The friction tunability is attributed to the charge transfer from MoS 2 to SAMs, which modulated the carrier density and hence the carrier-mediated friction behaviors in 2D MoS2. ab initio simulations and nanoscale mapping of work functions support this hypothesis. These SAMs-based heterostructures provide a potential tool to control friction in low-dimensional materials, and also an original perspective on the effect of electron–phonon coupling on friction at nanoscale.

Container ports play an important role in global logistics and supply chains by providing container handling services for container ships. In a port, container ships usually need the assistance of tugboats in order to undergo berthing, shifting, and unberthing movements. Effective scheduling of the tugboats for serving the ships is thus of great importance for ensuring safe and efficient container ship movements in a port. However, research on tugboat scheduling is scarce in the literature. We contribute to the literature by studying a real-life tugboat scheduling problem (Tug-SP). We formulate the Tug-SP using a mixed-integer linear programming (MILP) model taking into consideration various practical constraints. In view of the specific problem structure, we further develop six families of valid inequalities to strengthen the MILP model. To efficiently solve the Tug-SP, we develop a tailored branch-and-cut algorithm by incorporating these valid inequalities into a standard branch-and-bound solution framework. We evaluate the computational performance of the proposed branch-and-cut algorithm using a set of test instances generated from real-life ship traffic data collected from the Port of Singapore. The computational results validate the effectiveness of the proposed valid inequalities, and show that the branch-and-cut algorithm can optimally solve instances of realistic sizes with a reasonable amount of computation time.

The binary nanocomposites blended by carboxymethyl cellulose (CMC) and SiO2 nanoparticles were constructed to prepare the films with superior thermal stability and flame retardant properties. The incorporation of cellulose nanofibers(CNFs) and SiO2 nanoparticles were followed to prepare ternary nanocomposite films exhibiting excellent mechanical properties. The mechanism and chemical reaction of the thermal decomposition for the CMC/SiO2 composite membrane were proposed, which showed that the mass residuals were Na2CO3, SiO2 and Na2SiO3, Na2CO3 when the content of the SiO2 nanoparticles was lowered and higher than 9.6 %, respectively. Compared with the pure CMC, micro combustion calorimeter (MCC) showed that the total heat release (THR) and the peak heat release rate (PHRR) both decreased from 6.4 kJ/g to 5.8 kJ/g, 134 w/g to 27 w/g, respectively. Moreover, mechanical properties of CMC/CNFs/SiO2 membrane showed that the toughness and rigidity of the nanocomposites increased by 56.0 % and 63.0 % on the basis of CMC, respectively.

An environmental routing problem with multiple vehicle types is proposed.A hybrid genetic algorithm is developed.Vehicle speed and load capacity affect cost, customer satisfaction and pollution. With the goal of reducing cost, improving customer satisfaction and controlling the environmental pollution, a environmental routing optimization problem with time windows and multiple vehicle types is proposed by considering the concept of low-carbon logistics. A multi-objective vehicle routing problem (VRP) model with soft time-windows for multiple environmental vehicle types is presented, and a hybrid genetic algorithm (GA) is designed. Based on the experiments, the effectiveness of the algorithm is examined. With Pareto analysis, the relationship among the three objectives (distribution cost, customer satisfaction and environmental pollution) is examined. Sensitivity analysis is conducted to identify the influence of different type vehicle on the environmental performance. The results shows that the vehicle speed has strong correlation with the operation cost and environmental pollution, while the load capacity affects the operation cost, customer satisfaction and environmental pollution.

Based upon many theoretical findings on protein evolution, we proposed a ligand-selection model for the origin of proteins, in which the most ancient proteins originated from ATP selection in a pool of random peptides. To test this ligand-selection model, we constructed a random peptide library consisting of 15 types of prebiotic amino acids and then used cDNA display to perform six rounds of in vitro selection with ATP. By means of next-generation sequencing, the most prevalent sequence was defined. Biochemical and biophysical characterization of the selected peptide showed that it was stable and foldable and had ATP-hydrolysis activity as well.

As a new kind of clean and high-energy resource, natural gas hydrate possesses promising prospects in exploitation and utilization. The characteristic of gas production in clay-rich sediments need to be further clarified for developing hydrates more safely and efficiently. To study the dissociation behaviors of methane hydrates in clayey sediments, a novel pressure retention system was applied to create both confined and unconfined environments using a one-dimensional visual hydrate simulator. Two types of methane hydrate deposits were simulated, of which were characterized by excess gas and excess water, respectively. Direct depressurization results showed that in confined environment, the increase of clay content in sediments will result in the decrease of gas phase permeability and gas production rate, but have negligible effect on the final gas recovery ratio. In unconfined environment, the infiltration of overlying seawater will result in the migration of fine-grained particles and extremely low gas recovery ratio. Moreover, the build-up of vertical pressure gradient was observed due to the occurrence of sediment compaction during depressurization process in clayey sediments. It is of significance to improve the effective permeability of the reservior and suppress water seepage for exploiting hydrate safely and efficiently.

Two-dimensional carbon nanosheets have aroused extensive interest in the fields of electrochemical energy storage and conversion. In this work, a facile and friendly method was applied to fabricate nitrogen/sulfur co-doped graphene-like carbon nanosheets with hierarchical pore structure and large specific area (1753.01 m2 g−1) under the assistance of molten salt possessing the effects of template and activation. The typical morphology could provide abundant ion transport channels to enhance their diffusion and expose more accessibly active sites after doping heteroatoms simultaneously, which enabled the electrode to manifest a specific capacitance of 262.43 F g−1 under 1 A g−1, better capacitance retention of 78.05% after increasing current density to 20 A g−1 and superior cycle stability (96.28% after 10 000 cycles under 10 A g−1) in 6 M KOH. More importantly, the assembled all-solid-state supercapacitor with the as-obtained product as electrodes delivered higher energy densities of 22.26 Wh kg−1 and power density of 12 312.42 W kg−1 (1 M Na2SO4 electrolyte). This investigation may provide a strategy towards the simple and environmental preparation of carbon materials utilized in energy storage.

The multi-objective flexible job shop scheduling problem is solved using a novel path-relinking algorithm based on the state-of-the-art Tabu search algorithm with back-jump tracking. A routing solution is identified by problem-specific neighborhood search, and is then further refined by the Tabu search algorithm with back-jump tracking for a sequencing decision. The resultant solution is used to maintain the medium-term memory where the best solutions are stored. A path-relinking heuristics is designed to generate diverse solutions in the most promising areas. An improved version of the algorithm is then developed by incorporating an effective dimension-oriented intensification search to find solutions that are located near extreme solutions. The proposed algorithms are tested on benchmark instances and its experimental performance is compared with that of algorithms in the literature. Comparison results show that the proposed algorithms are competitive in terms of its computation performance and solution quality.

The interfacial tension of CO2 with hydrocarbons is an important thermophysical property involved in the process of enhancing the oil recovery. However, the systematical measurements of equilibrium interfacial tensions for systems of (CO2 + n-alkyl benzene) are still quite rare. In this work, the interfacial tensions of ten (CO2 + n-alkyl benzene) binary systems were measured at different temperatures including 323.15 K, 343.15 K (only for CO2/benzene system), and 353.15 K. The carbon number of n-alkyl benzene ranges from 6 to 20. The influences of temperature, pressure on the interfacial tension were taken into consideration. The measured IFT data range from 2.69 to 22.68 mN m−1. In addition, the density gradient theory was applied to simulate the interfacial tensions of these binary mixtures combined with the Patel-Teja equation of state plus volume translation approach. The average absolute deviation of interfacial tension between the predicted and experimental values is 7.06%.