An Alternative Fuel Refueling Station Location Model considering Detour Traffic Flows on a Highway Road System

With the development of alternative fuel (AF) vehicle technologies, studies on finding the potential location of AF refueling stations in transportation networks have received considerable attention. Due to the strong limited driving range, AF vehicles for long-distance intercity trips may require multiple refueling stops at different locations on the way to their destination, which makes the AF refueling station location problem more challenging. In this paper, we consider that AF vehicles requiring multiple refueling stops at different locations during their long-distance intercity trips are capable of making detours from their preplanned paths and selecting return paths that may be different from original paths for their round trips whenever AF refueling stations are not available along the preplanned paths. These options mostly need to be considered when an AF refueling infrastructure is not fully developed on a highway system. To this end, we first propose an algorithm to generate alternative paths that may provide the multiple AF refueling stops between all origin/destination (OD) vertices. Then, a new mixed-integer programming model is proposed to locate AF refueling stations within a preselected set of candidate sites on a directed transportation network by maximizing the coverage of traffic flows along multiple paths. We first test our mathematical model with the proposed algorithm on a classical 25-vertex network with 25 candidate sites through various scenarios that consider a different number of paths for each OD pair, deviation factors, and limited driving ranges of vehicles. Then, we apply our proposed model to locate liquefied natural gas refueling stations in the state of Pennsylvania considering the construction budget. Our results show that the number of alternative paths and deviation distance available significantly affect the coverage of traffic flows at the stations as well as computational time

Positioning Automated Guided Vehicles in a General Guide-path Layout

The locations of dwell points for idle vehicles in an automated guided vehicle (AGV) system determine the response times for pick-up requests and thus affect the performance of automated manufacturing systems. In this study, we address the problem of optimally locating dwell points for multiple AGVs in general guide-path layouts with the objective of minimizing the maximum response time in the system. We propose a mixed integer linear programming (MILP) formulation for the problem. We also develop a generic genetic algorithm (GA) to find near optimal solutions. The MILP model and GA procedure are illustrated using a two-dimensional grid layout problem. Our computational study shows that the proposed GA procedure can yield near optimal solutions for these test problems in reasonable time

Multimetallic (de)hydrogenation catalysed processes

The use of different metals working together in a synergistic way, allows synthetic transformations that are not achievable by other means. The metal cooperation becomes important in catalytic processes for the synthesis of sophisticated molecules or difficult transformations. A rationale design of multimetallic catalysed processes entails metal complexes and reaction conditions being compatible, which in general is not straightforward. A key feature for success found in all systems dealing with multimetallic processes is catalyst stability. The use of robust metal complexes increases the probability of success in the search of tandem catalytic processes. This microreview is based on the recent and most important findings of multimetallic catalysed processes that involved (de)hydrogenation reactions. The field constitutes a research area that is full of potential and can be foreseen that relevant applications will be described in the near future.MINECO (CTQ2015-69153-C2-2-R), Generalitat Valenciana (AICO/2015/039), Universitat Jaume I (P1.1B2015-09

A Flowshop Scheduling Problem With Transportation Times and Capacity Constraints

Although there are numerous methodologies and research studies on machine scheduling, most of the literature assumes that there is an unlimited number of transporters to deliver jobs from one machine to another for further processing and that transportation times can be neglected. These two assumptions are not applicable if one intends to generate an accurate schedule for the shop floor. In this research, a flowshop scheduling problem with two machines, denoted as M1 and M2, and a single transporter with capacity c is considered. The main focus is on the development of a dynamic programming algorithm to generate a schedule that minimizes the makespan. The transporter takes t1 time units to travel with at least one job from machine M1 to machine M2, and t2 time units to return empty to machine M1. When the processing times for all n jobs on machine M1 are constant, denoted as pj1≡p1, and the capacity of the transporter c is at least ()12121−⎥⎥⎤⎢⎢⎡+ptt, the computational complexity of the proposed algorithm is shown to be

Enhancement of gold catalytic activity and stability by immobilization on the surface of graphene

The catalytic performance of gold complexes is evaluated at the molecular level and when supported onto reduced graphene oxide (rGO). Gold complexes of general formula [(NHC)AuX] catalyse the synthesis of indoles via intramolecular hydroamination reaction of alkynes. The catalytic properties of the molecular gold complexes are highly improved when supported onto graphene. Faster reaction rates and higher catalyst stability are observed for the immobilized gold complexes. The use of graphene as support of molecular complexes has a positive benefit in the catalytic gold properties in terms of activity and stabilityThe authors thank the financial support from MINECO (CTQ2015-69153-C2-2-R), Generalitat Valenciana (AICO/2015/039) and Universitat Jaume I (P1.1B2015-09). D. V-E thanks MINECO for a FPU grant (FPU15/03011

Ruthenium molecular complexes immobilized on graphene as active catalysts for the synthesis of carboxylic acids from alcohol dehydrogenation

Ruthenium complexes containing N-heterocyclic carbene ligands functionalized with different polyaromatic groups (pentafluorophenyl, anthracene, and pyrene) are immobilized onto the surface of reduced graphene oxide. The hybrid materials composed of organometallic complexes and graphene are obtained in a single-step process. The hybrid materials are efficient catalysts for the synthesis of carboxylic acids from the dehydrogenation of alcohols in aqueous media. The catalytic materials can be recycled up to ten times without significant loss of activity. The catalytic activity of the pyrene derivative, Pyr-Ru (3) is enhanced when the ruthenium complex is anchored onto the surface of graphene. The carbonaceous material limits the degradation of the ruthenium complex resulting in increased activity and requiring lower catalyst loadings. The catalytic process of the pyrene hybrid material is heterogeneous in nature due to the strong interaction between the pyrene and graphene. The catalytic process of the anthracene and pentafluorophenyl hybrid materials is governed by the so-called ‘boomerang effect’. The ruthenium molecular complex is released from and returned to the graphene surface during the catalytic reaction. Mechanistic insight has been obtained experimentally and theoretically. The energy profile suggests that the rate-determining step is the water nucleophilic attack to a coordinated aldehyde complex to form a gem-diolate complex.The authors thank the financial support from MINECO (CTQ2015-69153-C2-2-R and CTQ2015- 67461-P), Generalitat Valenciana (AICO/2015/039), Universitat Jaume I (P1.1B2015-09) and Universidad de Zaragoza (UZ2014-CIE-01)

The HERC proteins and the nervous system

The HERC protein family is one of three subfamilies of Homologous to E6AP C-terminus (HECT) E3 ubiquitin ligases. Six HERC genes have been described in humans, two of which encode Large HERC proteins -HERC1 and HERC2- with molecular weights above 520 kDa that are constitutively expressed in the brain. There is a large body of evidence that mutations in these Large HERC genes produce clinical syndromes in which key neurodevelopmental events are altered, resulting in intellectual disability and other neurological disorders like epileptic seizures, dementia and/or signs of autism. In line with these consequences in humans, two mice carrying mutations in the Large HERC genes have been studied quite intensely: the tambaleante mutant for Herc1 and the Herc2+/530 mutant for Herc2. In both these mutant mice there are clear signs that autophagy is dysregulated, eliciting cerebellar Purkinje cell death and impairing motor control. The tambaleante mouse was the first of these mice to appear and is the best studied, in which the Herc1 mutation elicits: (i) delayed neural transmission in the peripheral nervous system; (ii) impaired learning, memory and motor control; and (iii) altered presynaptic membrane dynamics. In this review, we discuss the information currently available on HERC proteins in the nervous system and their biological activity, the dysregulation of which could explain certain neurodevelopmental syndromes and/or neurodegenerative diseases.Ministerio de Economía y Competitividad SAF2015-64171-

Catalytic Dehydrogenative Coupling of Hydrosilanes with Alcohols for the Production of Hydrogen On-demand: Application of a Silane/Alcohol Pair as a Liquid Organic Hydrogen Carrier

The compound [Ru(p-cym)(Cl)2(NHC)] is an effective catalyst for the room-temperature coupling of silanes and alcohols with the concomitant formation of molecular hydrogen. High catalyst activity is observed for a variety of substrates affording quantitative yields in minutes at room temperature and with a catalyst loading as low as 0.1 mol %. The coupling reaction is thermodynamically and, in the presence of a Ru complex, kinetically favourable and allows rapid molecular hydrogen generation on-demand at room temperature, under air, and without any additive. The pair silane/alcohol is a potential liquid organic hydrogen carrier (LOHC) for energy storage over long periods in a safe and secure way. Silanes and alcohols are non-toxic compounds and do not require special handling precautions such as high pressure or an inert atmosphere. These properties enhance the practical applications of the pair silane/alcohol as a good LOHC in the automotive industry. The variety and availability of silanes and alcohols permits a pair combination that fulfils the requirements for developing an efficient LOHC

Reduced Graphene Oxides as Carbocatalysts in Acceptorless Dehydrogenation of N-Heterocycles

[EN] The catalytic properties of graphene-derived materials are evaluated in acceptorless dehydrogenation of N-heterocycles. Among them, reduced graphene oxides (rGOs) are active (quantitative yields in 23 h) under mild conditions (130 degrees C) and act as efficient heterogeneous carbocatalysts. rGO exhibits reusability and stability at least during eight consecutive runs. Mechanistic investigations supported by experimental evidence (i.e., organic molecules as model compounds, purposely addition of metal impurities and selective functional group masking experiments) suggest a preferential contribution of ketone carbonyl groups as active sites for this transformation.Supported by MCIN/AEI/10.13039/501100011033/FEDER (Grant Nos. RTI2018-098237-B-C21, RTI2018-098237-BC22, and PID2019-105881RB-I00), Generalitat Valenciana (No. PROMETEU/2020/028), and Universitat Jaume I (No. UJI-B2018-23).Mollar-Cuni, A.; Ventura-Espinosa, D.; Martin, S.; García Gómez, H.; Mata, JA. (2021). Reduced Graphene Oxides as Carbocatalysts in Acceptorless Dehydrogenation of N-Heterocycles. ACS Catalysis. 11(23):1-6. https://doi.org/10.1021/acscatal.1c04649S16112