Improving the thermal performance of vertical ground heat exchanger by modifying spiral tube geometry: A numerical study.

Ground heat exchanger (GHE) is the most crucial element of a ground source heat pump (GSHP) system for building cooling and heating by the utilization of geothermal energy. Therefore, intending to enhance the performance of GHE, the present study conducts a computational investigation of the thermal performance of modified spiral tube vertical GHEs. Several modifications of uniform-pitched spiral GHE are made to increase its thermal performance. Some modifications are introduced as variable-pitched spiral tube GHE where spiral inlet pipes are densified in the lower part of GHEs by reducing pitch distance. Conversely, in some modifications, the position of the outlet straight pipe is changed. Water is considered as the working fluid and the inlet temperature of the water is maintained fixed at 300.15 K. After extensive analysis, it is evident that, when the outlet pipe is placed outside of the spiral coil, there is a 7.67 % enhancement in the thermal performance than a traditional uniform-pitched spiral tube GHE. However, modifications like variable-pitched spiral tube GHEs are not significant to improve the thermal performance due to the quick saturation of the ground soil temperature around the GHE pipes. To have a balance between heat transfer rate and pressure drop, thermal performance capability (TPC) and coefficient of performance improvement (COP imprvt ) criterion were evaluated and it is found that the uniform-pitched spiral tube GHE along with the outlet pipe at the outside of the spiral provides maximum thermal performance with a maximum TPC value of 1.062 and provides the positive value of COP imprvt criterion. The positive values of COP imprvt indicate that the spiral tube GHEs are energy efficient based on heat transfer and pressure drop. Moreover, spiral GHE with high-density polyethylene (HDPE), concrete pile, and sandy clay outperform the other materials for pipe, backfill, and soil, respectively. Specifically, HDPE pipe, concrete backfill, and sandy clay as soil offer around 7 %, 5 %, and 7.8 % higher thermal performance compared to polyethylene, sand silica, and clay, respectively.

Single/Multi-Network Conductive Hydrogels-A Review.

Hydrogels made from conductive organic materials have gained significant interest in recent years due to their wide range of uses, such as electrical conductors, freezing resistors, biosensors, actuators, biomedical engineering materials, drug carrier, artificial organs, flexible electronics, battery solar cells, soft robotics, and self-healers. Nevertheless, the insufficient level of effectiveness in electroconductive hydrogels serves as a driving force for researchers to intensify their endeavors in this domain. This article provides a concise overview of the recent advancements in creating self-healing single- or multi-network (double or triple) conductive hydrogels (CHs) using a range of natural and synthetic polymers and monomers. We deliberated on the efficacy, benefits, and drawbacks of several conductive hydrogels. This paper emphasizes the use of natural polymers and innovative 3D printing CHs-based technology to create self-healing conductive gels for flexible electronics. In conclusion, advantages and disadvantages have been noted, and some potential opportunities for self-healing single- or multi-network hydrogels have been proposed.

Beneficial Role of Citrus Fruit Polyphenols Against Hepatic Dysfunctions: A Review.

Alcoholic liver diseases and virus-induced hepatic dysfunctions are prevalent in western countries. Evidence also suggests that hyperglycemia and insulin resistance are key players in the development of hepatic diseases and their complications. Since the comorbid diseases like obesity, diabetes and vascular dysfunctions primarily affect liver, the modern therapies against other hepatic dysfunctions are becoming a major challenge to treat. In addition to these, polypharmacy and adverse drug reactions (ADRs) are further aggravating the phenomenon. Production of interleukins (IL) 1ß, tumor necrosis factors (TNF) α, nuclear factor (NF) κB, activator protein (AP) 1, macrophage inflammatory protein (MIP), toll-like receptor (TLR) 4, and several other harmful cytokines are often evaluated for clinical significance in hepatic complications as recommended by much evidence. On the other hand, transforming growth factors (TGF) ß, matrix metalloproteinases, and extracellular matrix- (ECM-) mediated hepatic fibrosis have been identified as major targets. However, modern medicines rely not only on synthetic compounds but also on herbal sources. Traditional therapies are gradually being acknowledged due to having fewer ADRs and other complications. Citrus fruits are generally seen all over the world and offer a great value as seasonal fruit. Several important biologically active components such as polyphenols, flavonols, carbohydrates, amino acids, and oils have been isolated from this family. Evidence suggests that polyphenol-based therapies have already proved their high potency against the production of inflammatory cytokines and profibrogenic factors. Along with the prevention of oxidative stress, these molecules hinder the generation of free radicals. Furthermore, polyphenols induce several defensive genes such as Nrf2, AMPK, superoxide dismutase, catalase, heme oxygenase (HO), Sirt1, and other important functional proteins to serve mitochondrial biogenesis. Therefore, this review will try to establish some molecular theories between citrus polyphenols and liver dysfunctions.

Free radical scavenging, antidiarrheal and anthelmintic activity of Pistia stratiotes L. extracts and its phytochemical analysis.

In this phyto-pharmacological screening of Pistia stratiotes L leaf and root extracts each separately in two different solvents demonstrated its potential medicinal value. Apparent antioxidant value is demonstrated by DPPH, Nitric oxide scavenging and Ferric ion reducing method. Additionally, total flavonoid and phenolic compounds were measured. The leaf methanolic extract scavenged both nitric oxide (NO) and DPPH radical with a dose dependent manner. But the pet ether fraction of root was found to have highest efficacy in Fe(3±) reducing power assay. Flavonoid was found to contain highest in the pet ether fraction of root (411.35mg/g) in terms of quercetin equivalent, similarly highest amount (34.96mg/g) of total phenolic compounds (assayed as gallic acid equivalents) were found to contain in the same fraction. The methanolic fractions appeared less cytotoxic compared to pet ether extracts. The plant extracts caused a dose dependent decrease in faecal droppings in both castor oil and magnesium sulphate induced diarrhea, where as leaf extracts in each solvent appeared most effective. Also, the plant extracts showed anthelmintic activity in earthworm by inducing paralysis and death in a dose dependent manner. At highest doses (50 mg/ml) all fractions were almost effective as the positive control piperazine citrate (10 mg/ml). Thus, besides this cytotoxic effect it's traditional claim for therapeutic use can never be overlooked.