Durability of Lubricated Icephobic Coatings under Various Environmental Stresses

Icephobic coatings interest various industries facing icing problems. However, their durability represents a current limitation in real applications. Therefore, understanding the degradation of coatings under various environmental stresses is necessary for further coating development. Here, lubricated icephobic coatings were fabricated using a flame spray method with hybrid feedstock injection. Low-density polyethylene represented the main coating component. Two additives, namely fully hydrogenated cottonseed oil and paraffinic wax, were added to the coating structure to enhance coating icephobicity. Coating properties were characterised, including topography, surface roughness, thermal properties, wettability, and icephobicity. Moreover, their performance was investigated under various environmental stresses, such as repeated icing/deicing cycles, immersion in corrosive media, and exposure to ultraviolet (UV) irradiation. According to the results, all coatings exhibited medium-low ice adhesion, with slightly more stable icephobic behaviour for cottonseed oil-based coatings over the icing/deicing cycles. Surface roughness slightly increased, and wetting performances decreased after the cyclic tests, but chemical changes were not revealed. Moreover, coatings demonstrated good chemical resistance in selected corrosive media, with better performance for paraffin-based coatings. However, a slight decrease in hydrophobicity was detected due to surface structural changes. Finally, paraffin-based coatings showed better resistance under UV irradiation based on carbonyl index and colour change measurements.

Improving the Mould and Blue-Stain-Resistance of Bamboo through Acidic Hydrolysis

Bamboo is much more easily attacked by fungus compared with wood, resulting in shorter service life and higher loss in storage and transportation. It has been long accepted that the high content of starch and sugars in bamboo is mainly responsible for its low mould resistance. In this paper, acetic acid, propionic acid, oxalic acid, citric acid, and hydrochloric acid were adopted to hydrothermally hydrolyze the starch in bamboo, with the aims to investigate their respective effect on the mould and blue-stain resistance of bamboo, and the optimized citric acid in different concentrations were studied. The starch content, glucose yields, weight loss, and colour changes of solid bamboo caused by the different acidic hydrolysis were also compared. The results indicated that weak acidic hydrolysis treatment was capable of improving mould-resistant of bamboo. The mould resistance increased with the increased concentration of citric acid. Bamboo treated with citric acid in the concentration of 10% could reduce the infected area ranging to 10–17%, the growth rating of which could reach 1 resistance. The content of soluble sugar and starch remained in bamboo decreased significantly from 43 mg/g to 31 mg/g and 46 mg/g to 23 mg/g, respectively, when the citric acid concentration varied from 4% to 10%. Citric acid treatments of 10% also caused a greatest surface colour change and weight loss. The results in this study demonstrated citric acid treatment can effectively reduce the starch grain and soluble sugars content and improve mould resistance of bamboo, which can be attributed to the reduction of starch grain and soluble carbohydrates (such as glucose, fructose, and sucrose, etc.) in bamboo.

Production of poultry feather hydrolysate using HCl and NaOH as a growth medium substrate for indigenous strains

The poultry feathers have a very high protein content due to it consists of 90% of crude protein, and it is an ideal material to obtain keratin protein. Due to Keratin’s difficulties and time-consuming decomposition, further processing is needed to degrade Keratin into simpler proteins that can be used as an alternative N-source. This study was aimed to evaluate the keratin hydrolysate from poultry feathers prepared by acidic (HCl) and alkaline (NaOH) compound utilization and its potency as the substrate medium for growth keratinolytic bacteria at a laboratory scale. Poultry feathers, including kampung (local breed) chicken feathers, layer chicken feathers, and local goose treat with HCL 12% and NaOH 20%. The results of the hydrolysate of poultry feathers using 12% HCl showed no significant changes. Visually, the feathers of birds that have been treated with 12% HCl show a colour change to brownish-yellow. The results of hydrolysis using NaOH showed better results than HCl for producing feather meals. The highest yield has occurred at local goose feathers at 95.7%, followed by Kampung and Layer chicken feathers at 93.17% and 78,75%. Based on the viability test, three indigenous strains (Bacillus cereus TD5B, B. cereus LS2B and Pseudomonas sp. PK4) grew in a medium with a substrate of kampung chicken feathers, layer chickens, and local goose feathers. It can be concluded that the hydrolysed poultry feathers made by NaOH 20% preparation had a potency as N-source in the bacterial growth medium.

Green synthesis of silver nanoparticles using Calotropis gigantea and its characterization using UV-Vis Spectroscopy

The use of Calotropis gigantea from Ie Seu-Um, Aceh Besar geothermal area for silver nanoparticles (AgNPs) synthesized has been reported. The process of synthesis AgNPs can be carried out with chemical methods, physical methods, and green synthesis methods, but in this study, the process is focused on the green synthesis method using C. gigantea flowers and leaves extract from Ie Seu-Um geothermal area, Aceh Besar. Phytochemical analysis showed that C. gigantea leaves contain alkaloids, steroids, tannins, phenolics, and saponins, while the flowers of C. gigantea contain alkaloids, terpenoids, steroids, flavonoids, tannins, phenolics, and saponins. The reaction of the AgNPs formation was observed by colour change formed. AgNPs-C. gigantea flower extract dan AgNPs-C. gigantea leaves extract showed the reddish-brown and brownish-yellow solution respectively after 48 h incubation in dark condition at room temperature. The result of the reaction characterized using UV-Vis Spectrophotometry showed that the phenomenon of Surface plasmone resonance (SPR) occurs in the mixture of nanoparticles formed. The concentration of AgNO3 as a reagent affected the SPR phenomenon. The result showed that particles formed are the same size and shape.

Colorimetric Detection of Acidic Pesticides in Water

A water-stable, porphyrin-based metal-organic framework (MOF) produces a distinct colour change in response to acids’ pKa and concentrations. This colour change is associated with the protonation of the N-atoms within...

Bio-mediated Synthesis of Silver Nanoparticles Using Fruit Extract of Ananas Comosus L. Merrill (Pineapple)

Silver is an agent used for different wounds and ulcer treatment as it is nontoxic. However, silver in an ionic or Nanoparticles form is highly toxic to microorganisms. Hence, silver Nanoparticles has wide range of applications than silver ion. Over the physical and chemical methods green synthesis is eco-friendly and cost effective. The present study reveals the formation of silver Nanoparticles by using the fruit extract (Ananas Comosus) by observing the colour change. The produced nanoparticles are characterized by the physicochemical techniques, X-ray diffraction, UV-Visible and antimicrobial activity. The diffraction peaks attributed to 2θ values of 38.11˚ and 44.27˚ (111, 200) reveals the formation of silver nanoparticles. UV-Vis spectrophotometer shows Surface Plasmon resonance (SPR) at 459 nm. The antibacterial studies promise the formation of silver nanoparticle with the ability to inhibit growth of Escherichia coli.

Biogenic Synthesis of Bi-Metallic (Zn-Cu) Nanoparticles by Leaf Extract of Citrus Limon and Evaluation of its Antibiofilm Activity Against E. coli

The rapid hike in the usage of metallic as well as non-metallic nanoparticles demands their increased synthesis. In our study we synthesized bimetallic Zn-Cu nanoparticles using the greener route i.e. dry leaves powder of Citrus limon as it is environment-friendly, cost-effective, has a high surface area to volume ratio and hence superior over monometallic nanoparticles synthesized via physical or chemical approach. UTI is the most common nosocomial infection and the bacteria associated with it usually is E. coli. This pathogen forms biofilm and makes it difficult to treat the disease in less time. Hence, antimicrobial as well as antibiofilm activity of synthesized bimetallic nanoparticles was checked against E. coli. Our experimental procedure involved the preparation of ethanolic plant extract using dry leaf powder followed by synthesis of bimetallic nanoparticles. Particles were then characterized by using biophysical techniques such as FTIR, Powder-XRD and SEM-EDX. Next, we identified bacteria isolated from environment and hospital source and prepared their pure cultures. Lastly, we carried out the antibacterial and antibiofilm activity of synthesized nanoparticles against isolated E. coli. Particles showed the colour change from blue to green upon synthesis and were found to be a triclinic primitive type with an average particle size calculated to be 27.76nm as seen in PXRD. FTIR analysis gave characteristic peaks of functional groups. SEM-EDX confirmed successful doping and grain size of the particle. Bacteria isolated from samples showed pink rods in gram staining indicating gram-negative bacilli. Biochemical findings confirmed E. coli in samples. Characteristic zones of inhibition in range 12-18mm establish good antibacterial properties with MIC of synthesized nanoparticles <0.5mg/ml and crystal violet assay assure antibiofilm properties of Zn-Cu. The result of the study can be advantageous to develop an understanding of the development of nano-based medicine for biofilm-producing pathogens.

Influence of Hydrogen Peroxide on Disinfection and Soil Removal during Low-Temperature Household Laundry

In the Water, Energy and Waste Directive, the European Commission provides for the use of household washing programmes with lower temperatures (30–40 °C) and lower water consumption. However, low washing temperatures and the absence of oxidising agents in the liquid detergents, and their reduced content in powder detergents, allow biofilm formation in washing machines and the development of an unpleasant odour, while the washed laundry can become a carrier of pathogenic bacteria, posing a risk to human health. The aim of the study was to determine whether the addition of hydrogen peroxide (HP) to liquid detergents in low-temperature household washing allows disinfection of the laundry without affecting the properties of the washed textiles even after several consecutive washes. Fabrics of different colours and of different raw material compositions were repeatedly washed in a household washing machine using a liquid detergent with the addition of 3% stabilised HP solution in the main wash, prewash or rinse. The results of the antimicrobial activity, soil removal activity, colour change and tensile strength confirmed the excellent disinfection activity of the 3% HP, but only if added in the main wash. Its presence did not discolour nor affect the tensile strength of the laundry, thus maintaining its overall appearance.

Functionalization of Gold Nanoparticles with Monosaccharide Mannose

Gold nanoparticles have found a wide range of application in biomedical sciences. Unique properties of these metal nanoparticles include surface plasmon resonance and size dependent colour change. Various molecules have been functionalized on the gold nanoparticles surface but carbohydrates have garnered attention due to their properties and their role in living systems. However certain challenges make carbohydrate-gold nanoparticles association difficult to obtain and stabilize. This study was carried out to chemically remodel gold nanoparticles by adding a monosaccharide mannose to its surface. A modified phase transfer method was used to synthesize gold nanoparticles. The surface of the nanoparticles was fixed with cyanuric chloride to serve as a linker. Mannose was then linked to the linker molecule. All three stages of the process, gold nanoparticles, and gold nanoparticles with linker and gold nanoparticles with the carbohydrate were analyzed for size and stability. Zeta potential and UV-vis data exhibited stable gold nanoparticles dispersion, successful binding of linker molecule as well as the carbohydrate. This study shows a simple, cost-effective and robust method of glycomodification of gold nanoparticles surface which can further find use in wide ranging applications.

Purification and Characterisation of Two Novel Pigment Proteins from the Carapace of Red Swamp Crayfish (Procambarus clarkii)

Pigment proteins play a vital role in the red colour change of the red swamp crayfish (Procambarus clarkii) shell after cooking. In this study, two red-change-related pigment proteins with molecular weights of approximately 170 and 43 kDa—denoted as F1 and F2, respectively—were purified by ammonium sulphate salting-out and size exclusion chromatography. F1 and F2 entirely comprised homomultimeric protein complexes composed of 21 kDa subunits. LC-MS/MS analysis showed that the 21 kDa protein subunit belonged to the crustacyanin family, named P. clarkii crustacyanin A2 (PcCRA2). The full-length cDNA of PcCRA2 was cloned, which encoded 190 amino acid residues and was highly homologous (91.58%) with Cherax quadricarinatus crustacyanin A. The predicted 3D structure showed that PcCRA2 had a β-barrel structure for pigment encapsulation. The colour change of F1 was first detected at 40 °C, and the red change occurred upon heating above 60 °C. Additionally, with increasing temperature, its β-sheet content increased, and its α-helix content reduced. Correlation analysis showed that the redness value of F1 was significantly related to the heating temperature and the β-sheet content.