Insertion free energy of PAP[5] water channels into block copolymer membranes

Biomimetic water channels embedded in copolymer membranes are promising candidates for next-generation desalination materials. Peptide appended pillar[5]arene (PAP[5]) is one such synthetic channel, which transports water at a rate comparable...

Mini Review: Forensic Value of Aquaporines

Forensic pathologists are routinely confronted with unclear causes of death or findings. In some scenarios, it can be difficult to answer the specific questions posed by criminal investigators or prosecutors. Such scenarios may include questions about wound vitality or causes of death when typical or landmark findings are difficult to find. In addition to the usual subsequent examinations to clarify unclear causes of death or special questions, immunohistochemical analysis has become increasingly important since its establishment in the early 40s of the 20th century. Since then, numerous studies have been conducted to determine the usefulness and significance of immunohistochemical investigations on various structures and proteins. These proteins include, for example, aquaporins, which belong to the family of water channels. They enable the transport of water and of small molecules, such as glycerol, through biological channels and so far, 13 classes of aquaporins could have been identified in vertebrates. The classic aquaporin channels 1, 2, 4 and 5 are only permeable to water. The aquaporin channels 3, 7, 9, and 10 are also called aquaglycerolporins since they can also transport glycerol. This mini review discusses the immunohistochemical research on aquaporins, their range of applications, and respective forensic importance, their current limitations, and possible further implementations in the future.

Detecting, extracting and classifying foreign objects in inter-basin channels to ensure water supply safety

Foreign objects (e.g., livestock, rafting, and vehicles) intruded into inter-basin channels pose threats to water quality and water supply safety. Timely detection of the foreign objects and acquiring relevant information (e.g., quantities, geometry, and types) is a premise to enforce proactive measures to control potential loss. Large-scale water channels usually span a long distance and hence are difficult to be efficiently covered by manual inspection. Applying unmanned aerial vehicles for inspection can provide time-sensitive aerial images, from which intrusion incidents can be visually pinpointed. To automate the processing of such aerial images, this paper aims to propose a method based on computer vision to detect, extract, and classify foreign objects in water channels. The proposed approach includes four steps, i.e., aerial image preprocessing, abnormal region detection, instance extraction, and foreign object classification. Experiments demonstrate the efficacy of the approach, which can recognize three typical foreign objects (i.e., livestock, rafting, and vehicle) with a robust performance. The proposed approach can raise early awareness of intrusion incidents in water channels for water quality assurance.

Physicochemical properties, total hydrocarbon content, and trace metals of water and sediments from major River Estuaries within the Niger Delta Region of Nigeria

Water and sediment samples from Cross River, Imo River, and Qua Iboe River Estuaries were collected and treated using standard analytical procedures. The samples were analyzed for their physicochemical properties, total hydrocarbon content (THC), and trace metals. Results obtained revealed that, the mean levels of total suspended solids (TSS), total dissolved solids (TDS), turbidity, colour, biochemical oxygen demand (BOD), THC, cadmium (Cd), iron (Fe), nickel (Ni), lead (Pb), and zinc (Zn) in water were higher than their acceptable limits in Nigeria. Whereas, the mean levels water pH, electrical conductivity (EC), dissolved oxygen (DO), nitrate, sulphate, phosphate, and copper (Cu) were within their acceptable limits. The results obtained also revealed that, the mean levels of nitrate, THC, and Fe in sediments were higher than their recommended limits. While the levels of pH, EC, sulphate, phosphate, Cd, Cu, Ni, Pb, and Zn in sediments were within their recommended limits. This study indicated that the anthropogenic activities by oil and oil-related companies within the Niger Delta Region of Nigeria may have contributed significantly to the high level of toxic substances in the water channels within the zone. The results obtained revealed that, the direct or indirect exposure to untreated water from the studied water channels may result in serious health challenges. Hence, the environment should be closely monitored to forestall a devastating situation in the region.

The energetic barrier to single-file water flow through narrow channels

Various nanoscopic channels of roughly equal diameter and length facilitate single-file diffusion at vastly different rates. The underlying variance of the energetic barriers to transport is poorly understood. First, water partitioning into channels so narrow that individual molecules cannot overtake each other incurs an energetic penalty. Corresponding estimates vary widely depending on how the sacrifice of two out of four hydrogen bonds is accounted for. Second, entropy differences between luminal and bulk water may arise: additional degrees of freedom caused by dangling OH-bonds increase entropy. At the same time, long-range dipolar water interactions decrease entropy. Here, we dissect different contributions to Gibbs free energy of activation, ΔG‡, for single-file water transport through narrow channels by analyzing experimental results from water permeability measurements on both bare lipid bilayers and biological water channels that (i) consider unstirred layer effects and (ii) adequately count the channels in reconstitution experiments. First, the functional relationship between water permeabilities and Arrhenius activation energies indicates negligible differences between the entropies of intraluminal water and bulk water. Second, we calculate ΔG‡ from unitary water channel permeabilities using transition state theory. Plotting ΔG‡ as a function of the number of H-bond donating or accepting pore-lining residues results in a 0.1 kcal/mol contribution per residue. The resulting upper limit for partial water dehydration amounts to 2 kcal/mol. In the framework of biomimicry, our analysis provides valuable insights for the design of synthetic water channels. It thus may aid in the urgent endeavor towards combating global water scarcity.

Towards multifunctional building elements: thermal activation of a composite interior GFRP slab

Modular multifunctional building elements can overcome major disadvantages of the traditional sequential design and become prospective design solutions for sustainable construction. Thus, this work explores lightweight glass fiber-reinforced polymer (GFRP) profiles capabilities as multifunctional load-bearing slab modules in buildings. By adding water channels in a cellular structure of pultruded GFRP elements, hydronic radiant thermal conditioning of the indoor space can be enabled. Additionally, the water channels can protect critical slabs in case of a fire. A preliminary design of a multifunctional GFRP slab is performed for an office case study building by modifying a commercial slab profile with triangular channels. The thermal design load of the slab unit is determined using Rhino 6, and heat conduction and convective heat transfer for ceiling cooling and floor heating/cooling cases are investigated using ANSYS Fluent. The results show that a commercial GFRP profile can be modified to accommodate water channels and provide adequate heating and cooling at the upper or lower face. In addition, Serviceability Limit State is verified and required water flow adjustment in case of a fire outbreak scenario is discussed. Thus, the GFRP radiant slab has the potential as a pre-fabricated alternative for traditional embedded radiant systems.