Organic Phase Change Materials for Thermal Energy Storage: Influence of Molecular Structure on Properties

Materials that change phase (e.g., via melting) can store thermal energy with energy densities comparable to batteries. Phase change materials will play an increasing role in reduction of greenhouse gas emissions, by scavenging thermal energy for later use. Therefore, it is useful to have summaries of phase change properties over a wide range of materials. In the present work, we review the relationship between molecular structure and trends in relevant phase change properties (melting temperature, and gravimetric enthalpy of fusion) for about 200 organic compounds from several chemical families, namely alkanes (paraffins), fatty acids, fatty alcohols, esters, diamines, dinitriles, diols, dioic acids, and diamides. We also review availability and cost, chemical compatibility, and thermal and chemical stabilities, to provide practical information for PCM selection. Compounds with even chain alkyl lengths generally give higher melting temperatures, store more thermal energy per unit mass due to more efficient packing, and are of lower cost than the comparable compounds with odd alkyl chains.

Identifying the Optimal Packing and Routing to Improve Last-Mile Delivery Using Cargo Bicycles

Efficient vehicle routing is a major concern for any supply chain, especially when dealing with last-mile deliveries in highly urbanized areas. In this paper problems considering last-mile delivery in areas with the restrictions of motorized traffic are described and different types of cargo bikes are reviewed. The paper describes methods developed in order to solve a combination of problems for cargo bicycle logistics, including efficient packing, routing and load-dependent speed constraints. Proposed models apply mathematical descriptions of problems, including the Knapsack Problem, Traveling Salesman Problem and Traveling Thief Problem. Based on synthetically generated data, we study the efficiency of the proposed algorithms. Models described in this paper are implemented in Python programming language and will be further developed and used for solving the problems of electric cargo bikes’ routing under real-world conditions.

Application of a Natural Antioxidant from Grape Pomace Extract in the Development of Bioactive Jute Fibers for Food Packaging

There is an increasing demand for the use of new food packaging materials. In this study, natural jute fibers impregnated with a Petit Verdot Red Grape Pomace Extract (RGPE) was proposed as a new active food packaging material. Pressurized Liquid Extraction (PLE) and Enhanced Solvent Extraction (ESE) techniques were employed to obtain the bioactive RGPE. Afterward the supercritical solvent impregnation conditions to obtain RGPE-natural jute fibers were studied, by varying pressure, modifier percentage and dried RGPE mass. PLE technique offered the highest bioactive extract at 20 MPa, 55 °C, 1 h residence time using C2H5OH:H2O (1:1 v/v), providing an EC50 of 3.35 ± 0.25 and antibacterial capacity against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa (MIC of 12.0, 1.5 and 4.0 mg/mL RGPE respectively). The natural jute fibers impregnated with 3 mL of that RGPE (90 mg/mL) at 50 MPa and 55 °C generated the most efficient packing material with regards to its food preservation potential.

Design and Analysis of a Remotely Operated Mini Forklift Bot

This work is concerned with the design, analysis and programming of a scaled down version of an electric forklift robot. An advantageous consequence of this device is the development of space saving storage units that allow for efficient packing of lighter goods into areas that while not built for human movement, allow ample space for movement of our forkliftt bot. This is especially important in cases where each cubic meter of the storage unit is valuable, for example, refrigerated goods storage units. Each part of the robot was either carefully selected or designed from scratch in the pursuit of maximizing the load bearing capacity to design-weight ratio. As such, structural analysis was conducted for each part using the Ansys Workbench simulation package. Furthermore, motors that were operated using standard electronic circuits were installed to remotely control the traversal of the bot, while cameras and sensors were employed to monitor its surroundings and movements. The next step was to program the logic circuit and link the various components wired to it. Here the main control device used was an Arduino, which is an integrated open-source electronic platform that allows for precision control of the various electronic components in accordance with the operator’s inputs. The hardware used for passing instructions to the Arduino was a common smart phone on which a self-developed android app was installed. Writing a program for this involves careful calibration of the power and position of the driving components and the electric signals they receive.

Graph Properties of the Adult Drosophila Central Brain

The recent Drosophila central brain connectome offers the possibility of analyzing the graph properties of the fly brain. Crucially, this connectome is dense, meaning all nodes and links are represented, within the limits of experimental error. We consider the connectome as a directed graph with weighted edges. This enables us to look at a number of graph properties, compare them to human designed logic systems, and speculate on how this may affect function. We look at input and output distributions, randomness of wiring, differences between compartments, path lengths, proximity of strong connections, known computational structures, electrical response as a function of compartment structure, and evidence for efficient packing.

Ideal supplementary cementing material – Metakaolin: A review

Though being an ancient trend, usage of the homogeneous material cement in the construction industry is steadily getting eradicated with the springing up of supplementary cementing materials (SCM). Metakaolin is an imminent mineral admixture extracted from the mineral ore kaolinite, which enhances the interfacial zone by more efficient packing at the cement paste-aggregate particle interface, thus reducing the bleeding and producing a denser, more homogeneous transition zone microstructure. This paper depicts the various repercussions of the pozzolanic material metakaolin in the fresh and hardened properties of concrete when replaced with cement in finite amount. Also, it states the behavior of high-performance concrete and self-compacting concrete with metakaolin.

Fundamental helical geometry consolidates the plant photosynthetic membrane

Plant photosynthetic (thylakoid) membranes are organized into complex networks that are differentiated into 2 distinct morphological and functional domains called grana and stroma lamellae. How the 2 domains join to form a continuous lamellar system has been the subject of numerous studies since the mid-1950s. Using different electron tomography techniques, we found that the grana and stroma lamellae are connected by an array of pitch-balanced right- and left-handed helical membrane surfaces of different radii and pitch. Consistent with theoretical predictions, this arrangement is shown to minimize the surface and bending energies of the membranes. Related configurations were proposed to be present in the rough endoplasmic reticulum and in dense nuclear matter phases theorized to exist in neutron star crusts, where the right- and left-handed helical elements differ only in their handedness. Pitch-balanced helical elements of alternating handedness may thus constitute a fundamental geometry for the efficient packing of connected layers or sheets.

Anion Influence on the Packing of 1,3-Bis(4-Ethynyl-3-Iodopyridinium)-Benzene Halogen Bond Receptors

Rigid and directional arylethynyl scaffolds have been widely successful across diverse areas of chemistry. Utilizing this platform, we present three new structures of a dicationic 1,3-bis(4-ethynyl-3-iodopyridinium)-benzene halogen bonding receptor with tetrafluoroborate, nitrate, and hydrogen sulfate. Structural analysis focused on the receptor conformation, anion shape, solvation, and long range packing of these systems. Coupled with our previously reported structures, we concluded that anions can be classified as building units within this family of halogen bonding receptors. Two kinds of antiparallel dimers were observed for these dicationic receptors. An off-centered species was most frequent, present among geometrically diverse anions and assorted receptor conformations. In contrast, the centered antiparallel dimers were observed with receptors adopting a bidentate conformation in the solid-state. While anions support the solid-state formation of dimers, the molecular geometry and characteristics (planarity, rigidity, and directionality) of arylethynyl systems increase the likelihood of dimer formation by limiting efficient packing arrangements. The significantly larger cation may have considerable influence on the solid-state packing, as similar cationic arylethynyl systems also display these dimers.