Repellent Ability Research Articles

Improving sizing performance of middle layer of liquid packaging board containing high-yield pulp

As the important part of liquid packaging board, the middle layer is generally produced from a mixed pulp furnish by unbleached softwood kraft pulp and high-yield pulp (HYP). However, the addition of HYP would bring unsatisfactory properties (e.g. hydrophilicity) to liquid packaging board. Herein, in this study, the sizing performance of middle layer of liquid packaging board was evaluated by varying the kraft pulp to HYP ratios of middle layer, the dosage of sizing agent and cationic additives etc. It showed that the edge penetration value and Cobb value of middle layer illustrated a better liquid repellence with the addition of sizing agent. The improved sizing performance of the middle layer of liquid packaging board can be ascribed to the excellent performance of the added cationic additive (polyethyleneimine (PEI), alums) for trapping anionic trash via neutralization/flocculation effects. In addition, a binary cationic additive system (Al2(SO4)3-PEI) was proposed to study the improvement on the sizing performance. It was found that a desirable liquid repellence ability can be successfully achieved at a binary additive system containing 1.5% of Al2(SO4)3 and 0.2% of PEI, even when dosage of rosin sizing agent was reduced to 0.5%. The study put forwards a practical approach to improve the sizing performance, especially the liquid repellence ability of liquid packaging board when containing HYP.

Effects of Selected Pesticidal Plants on Termites Affecting Maize Production in Arusha, Tanzania

Investigations under laboratory and field conditions were carried out with purpose of understanding the effects of pesticides of Cupressus lusitanica, Tephrosia vogelii, Eucalpytus dalrympleana, Lantana camara and Azadirachta indica in the control of termites which affect maize production in Arusha, Tanzania. Termites were collected before and during maize season of 2018 and identified at the Tropical Pesticides Research Institute (TPRI) laboratory. A total of 5279 out of 5307 termite species identified belong to genus Macrotermes, 23 species to genus Odontotermes and 5 species were unknown. The results entailed that the area is rich in species of genus Macrotermes. Moreover, concentrations i.e. 5 g, 10 g and 20 g of each botanical were tested for Macrotermes spp. mortality and repellency ability in the laboratory using a completely randomized design (CRD) with three replicates. The results showed that 98.33% Macrotermes spp. mortality was caused by T. vogelii followed by 93.33% recorded from E. dalrympleana after 24 hours. Besides, C. lusitanica repelled Macrotermes spp. by 97% followed by 95% recorded from T. vogelii and E. dalrympleana each. For field trials, 20 g of each botanical was applied using randomized complete block design (RCBD) with four replicates. The results obtained from field indicated that T. vogelii was more effective to protect maize with an average of 6 maize stands and 3.4 kg of dry total weight of maize grains next to positive control per plot. Also, average of 4 maize stands and 3 kg dry total weight of maize grains were recorded from treatments of E. dalrympleana and C. lusitanica each. Such results highlight the potential of developing bio-termiticides from T. vogelii, C. lusitanica and E. dalrympleana to control Macrotermes spp.

Flexible Driving Mechanism Inspired Water Strider Robot Walking on Water Surface

The agile and efficient locomotion of water striders on water surface is attributed to the water repellency ability of their slender legs. The legs are usually treated as rigid beams, neglecting the effect of flexible deformation on its movement. Several studies proved that the stable floating ability of water striders is closely related to the flexible legs. This paper focuses on exploring the flexible driven mechanism between the insect and the surface of water and applied them to design a robot. The spatial deformation and force models of the driving legs are established and analyzed based on the Euler-Bernoulli's beam theory. The influence of flexural rigidity and depth of a driving leg on the rowing speed is studied. Results indicates that a flexible driving leg can effectively increase its critical rowing speed and ensure that it does not penetrate the water surface at a higher speed, thus achieving a bigger driving force. Then a water strider robot capable of walking on water surface is proposed, which possesses ellipse-like spatial trajectories by using a limit pin-linkage. The driving legs are fabricated by different stiffness materials. Finally, the skating experiments of the robots with different stiffness of the driving legs were carried out. The results verified that the maximum rowing frequency of the flexible driving legs and maximum moving speed of the robot are more than 30% higher than those with rigid legs, respectively. Moreover, a similarity analysis of hydrodynamic characteristic constants reveals that the flexible driving robot is more analogous to the biological water striders.

Study on humic acid derived from EFB based vermicompost as biopesticide

The increment of global population by 1.1% annually demands higher agricultural yield to ensure sustainable food source which leads to intensive usage of chemical fertilizer and pesticide. However, this practice poses various environmental and health problems which ultimately encourages the development of safer organic fertilizers and bio-pesticides. One potential method is to utilize Humic Acid (HA), a natural plant’s growth promoter, present in organic compost as an environmental-friendly fertilizer as well as insect control agent. This study investigated the effectiveness of HA extracted from vermicompost of Palm Oil Empty Fruit Bunches (EFB) as biopesticide. HA was extracted from the vermicompost via alkaline extraction followed by precipitation in strong acid that resulted in HA mass yield of 2.336%. The insect repellent ability of HA, Garlic Extract (GE) and 87% GE + 13% HA was investigated by spraying the solution onto soil samples in the presence of crickets. The effectiveness of the insect control agents was determined by recording the number of crickets avoiding the infected area. The test revealed that the insects exhibited most repulsive behavior towards 87% GE + 13% HA, followed by HA and lastly GE. The results indicate that HA has the potential to be used as biopesticide, with higher prospect when combined with GE. The dual benefits of HA utilization as plant growth promoter and insect repellent promise a more sustainable approach towards modern agriculture.

One-step machining of hierarchical micro-nano structures on Al-Mg alloy as superamphiphobic substrate for amplified SERS trace detection

Ultra-trace detection from polluted solution makes great contribution to environmental monitoring, food safety and medical analysis. However, its common difficulty arises in concentrating analytes on easily accessible substrate for highly amplified detection intensity. Herein, a superhydrophobic Al-Mg alloy surface focusing on droplet condensation and analyte detection is fabricated by an environment-friendly, efficient and low-cost machining process for surface enhanced Raman scattering (SERS) analyses. The micro-scale craters covered with nano-scale terrace-like structures have been prepared by one-step wire electrical discharge machining (WEDM). Meanwhile, wet abilities of hierarchical structures have been investigated after stearic acid modification. Results show that the as-prepared surface exhibits excellent repellent ability to water and oil drops. The resultant superamphiphobic surface also displays a 3-fold higher SERS intensity over hydrophilic Al-Mg alloy substrate. The corresponding SERS signals also show well signal reproducibility. This work sheds positive insights into fabricating accessible and efficient active substrates for SERS detection and extending potential applications of Al-Mg alloys in ultra-trace analysis in the future.

Interfacial Conformation of Hydrophilic Polyphosphoesters Affects Blood Protein Adsorption.

Synthetic polymers are commonly used as protein repelling materials for a variety of biomedical applications. Despite their widespread use, the fundamental mechanism underlying protein repellence is often elusive. Such insights are essential for improving existing and developing new materials. Here, we investigate how subtle differences in the chemistry of hydrophilic polyphosphoesters influence the adsorption of the human blood proteins serum albumin and fibrinogen. Using thermodynamic measurements, surface-specific vibrational spectroscopy, and Brewster angle microscopy, we investigate protein adsorption, hydration, and steric repulsion properties of the polyphosphoester polymers. Whereas both surface hydration and polymer conformation of the polymers vary substantially as a consequence of the chemical differences in the polymer structure, the protein repellency ability of these hydrophilic materials appears to be dominated by steric repulsion.

Environmental health risks and benefits of the use of mosquito coils as malaria prevention and control strategy

BackgroundMalaria is an infectious disease that causes many deaths in sub-Saharan Africa. In resource-poor malaria endemic communities, mosquito coils are commonly applied in households to repel the vector mosquito that transmits malaria parasites. In applying these coils, users have mainly been interested in the environmental health benefits potentially derived from repelling the mosquito, while oblivious of the environmental health risks that may be associated with exposure to emissions from the use of mosquito coil. This study evaluated the effectiveness of the mosquito coil, ascertained and/or estimated the toxic emissions that may emanate from the coil, and determined its overall appropriateness by conducting a risk–benefit analysis of the use of this strategy in malaria prevention at household levels.MethodsThe repellent ability of mosquito coils was tested by conducting a mosquito knockdown/mortality test in experimental chambers synonymous of local room spaces and conditions. The gaseous and particulate emissions from the mosquito coil were also analysed. Additional scenarios were generated with the Monte Carlo technique and a risk–benefit analysis was conducted applying @Risk software.ResultsMosquito mortality arising from the application of various mosquito coils averagely ranged between 24 and 64%, which might not provide adequate repellency effect. Emissions from the mosquito coil were also found to contain CO, VOCs, SO2, NO2, PM2.5 and PM10. The Hazard Index of the respective pollutants characterized over a lifetime exposure scenario was low (< 1 for each pollutant), which suggests that the concentrations of the specific chemicals and particulate matter emitted from the mosquito coil may not constitute adverse environmental health risk.ConclusionAlthough the risk of morbidity from the use of the mosquito coil was low, the coil yielded limited protection as a mosquito avoidance method. It may, therefore, have a reduced benefit in controlling malaria and should be applied sparingly in a highly regulated manner only when traditionally proven effective vector control strategies are not available or too expensive for resource-poor malaria endemic regions.

Evaluation of Wormwood Extract as a Bird Repellent Material and Antagonistic Agent against Feces Fungi

Wormwood extract (Artemisia herba-alba) was evaluate as a repellent for the house sparrow, Passer domesticus under laboratory and field conditions. Fungal species belonging to P. domesticus feces and the antifungal activity of A. herba-alba extract against these fungi were also investigated. The results showed that the highest concentration (10%) has the highest repellent effect with wheat consumption mean of 0.16 g and 0.15 g compared to the control (plain wheat) after four days of the laboratory and field experiments. It is worthy to mention that the lowest concentration 2.5% exhibited a high repellent effect at the first day of experiment and subsequently lost its repellent ability. Among the pathogenic fungi in feces, Rhizopus stolonifer (the most predominant fungus 31.7%) followed by Fusarium subglutinans (23.8%), Paecilomyces variotii (12.4%), Cladosporium sphaerospermum (9.2%), Aspergillus flavus (7.3%), Aspergillus niger (6%) and Aspergillus versicolor (5%). Whereas Penicillium digitatum was the least isolated fungus with occurrence 4.6%. The susceptibility of these fungi to A. herba-alba extract increased by increasing the extract concentration. The highest concentration 10% showed the highest antifungal activity against A. versicolor with mean of inhibition zone 24.3 mm. However, the lowest concentration 2.5% of this extract did not show any antifungal effects against P. digitatum, R. stolonifer and A. niger. It is concluded that wormwood is a promising biologically safe bird repellent and effective antifungal agent against pathogenic fungi of bird feces. It is economical for use than synthetic pesticides that one expensive and relatively difficult to obtain.

REPELLENT ABILITY OF LERAK (Sapindus rarak DC) FRUIT EXTRACT AND KIRINYUH (Chromolaena odorata L.) LEAF EXTRACT ON Callosobruchus maculatus F WAREHOUSE PESTS

The aim of this research is to know the repellent ability of lerak fruit extract (Sapindus rarak DC.) and kirinyuh leaf extract (Chromolaena odorata) against Callosobruchus maculatus warehouse pests. The research activity was conducted in October - December 2016 at Entomology Laboratory, SEAMEO BIOTROP Bogor. This research used two experiments that were using lerak fruit extract and kirinyuh leaf extract. The experimental design used was Completely Randomized Design with three replications for each concentration level of extract material. The extract concentrations used for the preliminary test were 1.0%; 2.0%; 3.0%; 4.0% and 5.0%. In the main test the concentration refers to the results of the preliminary test. The concentration of lerak fruit extract used for the main test were 1.5%; 3.0%; 4.5%; 6.0% and 7.5% (v / v), the concentration of kirinyuh leaf extract were 0.0%; 2.5%; 5.0%; 7.5% and 10.0% (v / v). The effectiveness of repellent ability be classified well if repellent ≥80%, good enough if 60% ≤ repellent &lt;80% and less good if repellent &lt;60%. The highest repellent content of lerak fruit extract on 72 hours after treatment (JSP) was 77.9% occurring at 4.5% extract concentration and highest repellent of kirinyuh leaf extract on 72 JSP was 82.73% occurring at 10.0% extract concentration. Repellent ability of kirinyuh leaf extract is better than repellent ability of lerak fruit extract. Keywords: repellent power, vegetable extract, extract concentration, pest controlling

Versatile superamphiphobic cotton fabrics fabricated by coating with SiO2/FOTS

A multifunctional superamphiphobic cotton fabric was fabricated by coating silica nanoparticles on the cotton fabric surface and further modification by 1H,1H,2H,2H-perfluorooctyltrichlorosilane (FOTS). The fluctuant woven fabric and the fluffy spherical SiO2 nanoparticles constructed a dual micro/nano-structures. The surface free energy of the fabric composite was reduced by FOTS modifier. The interplay of the structured and perfluorinated SiO2 nanoparticles could not only endow the fabric highly liquid repellent ability, but could also to enhance the coating stability. The prepared cotton fabrics exhibited high liquid repellency to water, colza oil and n-hexadecane with lower surface tension, showing a contact angle of 158°, 152°, and 153°, respectively. The results demonstrated that superamphiphobic cotton fabric possessed desirable chemical and mechanical durability, self-cleaning and self-healing property, the robust and multifunctional fabric would find innovative opportunities for practical applications.

The Effect of ginger essential oil (Zingiber Officinale) as repellent towards Aedes aegypti

The effect of ginger essential oil (Zingiber officinale) as an effective repellent against the Aedes aegypti mosquitoPurposeThe purpose of this paper was to determine the ability of ginger essential oil (Zingiber officinale) as a repellent towards Aedes aegypti. MethodsThis research was a true experimental study. The tests performed in this study were negative control tests, with protective ability test of telon plus oil and ginger essential oil 4% in telon oil involving 25 Aedes aegypti adult female mosquitoes. ResultsThe study found that the average protective ability of ginger essential oil 4 % in telon oil was 100% at minute 5, 10, and 15, while telon oil plus (positive control) was 5%, 36%, and 33%. In the protective ability test of ginger essential oil 4% in telon oil has the better repellent ability or protective ability compared to telon plus, which can provide protective ability up to 60 minutes at 91.95% while telon plus oil provides protective ability around 59.51%. In the length of protection test ginger essential oil 4% in telon oil gave an average of protection from biting until 61.67 minutes, while telon oil gives 8.33 minutes and 11.67 minutes of telon plus oil. Based on Probit analysis ginger essential oil 4% in telon oil can repel 90% of experimental mosquitoes up to 89.87 minutes. ConclusionGinger essential oil 4% in telon oil has the better repellent ability and length of protection compared to telon plus oil. Ginger essential oil 4% in telon can be used as a repellent active ingredient.

Fabrication and characterization of superhydrophobic copper fiber sintered felt with a 3D space network structure and their oil–water separation

This study reports the fabrication of a novel stable superhydrophobic and superoleophylic porous metal material on a copper fiber sintered felt (CFSF) substrate via a simple solution-immersion method. Oxidation and modification times are two important factors related to the level of hydrophobicity; oxidation for 1h and modification for 24h are appropriate to build a superhydrophobic CFSF surface with a water contact angle of 152.83° and a kerosene contact angle of 0°. The stability and high temperature resistance of superhydrophobic CFSF were studied. A novel device was designed to measure the water repellent ability of the treated CFSF. The results indicated that the water repellent ability of superhydrophobic CFSF was almost constant after 40 cycles of sanding. Both the water contact angle and the microstructure of the modified CFSF surface remained nearly unchanged after experiencing ultrasonic vibration for 1min. The modified CFSF surface maintains super hydrophobicity after being treated at 180°C for 1h. The separation efficiencies for different types of oils and organic solvents (kerosene, chloroform, n-hexane and gasoline) are more than 96%. The modified CFSF retains a high robustness of separation efficiency even after it is recycled for the separation of kerosene and water for more than 10 times.

Fabrication of Superhydrophobic and Luminescent Rare Earth/Polymer complex Films.

The motivation of this work is to create luminescent rare earth/polymer films with outstanding water-resistance and superhydrophobicity. Specifically, the emulsion polymerization of styrene leads to core particles. Then core-shell-structured polymer nanoparticles are synthesized by copolymerization of styrene and acrylic acid on the core surface. The coordination reaction between carboxylic groups and rare earth ions (Eu3+ and Tb3+) generates uniform spherical rare earth/polymer nanoparticles, which are subsequently complexed with PTFE microparticles to obtain micro-/nano-scaled PTFE/rare earth films with hierarchical rough morphology. The films exhibit large water contact angle up to 161° and sliding angle of about 6°, and can emit strong red and green fluorescence under UV excitation. More surprisingly, it is found that the films maintain high fluorescence intensity after submersed in water and even in aqueous salt solution for two days because of the excellent water repellent ability of surfaces.

Synthesis and performance of alkyd–acrylic hybrid binders

Preparation and properties of alkyd–acrylic hybrids have been studied. Hybrids with different alkyd–acrylic ratios and acrylic parts were prepared via free radical polymerization of acrylic monomers in a presence of an unsaturated alkyd resin using emulsion polymerization technique. The binders were characterized according to their solid content, conversion, viscosity, pH and particle size. Evidence on formation of true copolymer was obtained via NMR spectroscopy and molecular weight and glass transition temperature measurements, as well as via performance studies. The performance evaluation was focused on investigation of drying, penetration and water repellency ability, as well as on film formation and surface topography studies. The binders were compared to references of an alkyd emulsion, acrylic latex and a blend made of them. The results showed that alkyd–acrylic hybrids with synergistic and improved properties can be prepared.

Characteristics modification of TiO2 thin films by doping with silica and alumina for self-cleaning application

Self-cleaning hydrophilic and hydrophobic properties of TiO2-based thin films on glass substrates have been investigated in this study. The addition of SiO2 into TiO2 can increase the wettability of films and maintain the hydrophilic state for a long time even in the dark. The contact angle of water on deposited films containing 15% SiO2 is less than 2° after 2 h of UV illumination. These TiO2–SiO2 films exhibit excellent antifogging characteristics. Meanwhile, TiO2–Al2O3 films possess high water repellent ability and the photo-induced self-cleaning can take place even in visible light. The TiO2 thin film containing 33% of Al2O3 shows a high hydrophobic state with a water contact angle of 73° after being irradiated with sunlight for 2 h. A comparison of hydrophilic TiO2–SiO2 and hydrophobic TiO2–Al2O3 films demonstrates the ability to modify the TiO2 thin film properties for self-cleaning applications.

Buoyant force and sinking conditions of a hydrophobic thin rod floating on water

Owing to the superhydrophobicity of their legs, such creatures as water striders and fisher spiders can stand effortlessly, walk and jump quickly on water. Directed toward understanding their superior repellency ability, we consider hydrophobic thin rods of several representative cross sections pressing a water surface. First, the shape function of the meniscus surrounding a circular rod is solved analytically, and thereby the maximal buoyant force is derived as a function of the Young's contact angle and the rod radius. Then we discuss the critical conditions for a rod to sink into water, including the maximal volume condition and the meniscus-contact condition. Furthermore, we study the sinking conditions and the maximal buoyant forces of hydrophobic long rods with elliptical, triangular, or hexagonal cross-section shapes. The theoretical solutions are quantitatively consistent with existing experimental and numerical results. Finally, the optimized structures of water strider legs are analyzed to elucidate why they can achieve a very big buoyant force on water.

Physicochemical Characterization of Densely Packed Poly(ethylene glycol) Layer for Minimizing Nonspecific Protein Adsorption

Modification of the surface with densely packed poly(ethylene glycol) (PEG) brush layer was studied to improve the protein repellent ability of the surface. A PEG-brushed layer was constructed on a gold substrate using a PEG possessing a mercapto group at the chain end. The density of the PEG brushed layer substantially increased with repetitive adsorption/rinse cycles of the PEG on the gold substrate, allowing dramatic reduction of nonspecific protein adsorption. Notably, formation of a short, filler layer of PEG (2 kDa) in the preconstructed longer PEG brushed layer (5 kDa) achieved high density brush and almost complete prevention of nonspecific protein adsorption. On the other hand, surface modification with only long PEG chain (5 kDa) showed lower PEG brush density regardless of repetitive immobilization. Detailed characterization of the PEGylated surface was done from the physicochemical (QCM, contact angle, and SPR) as well as the biological (protein adsorption) point of view to highlight the relation between the PEG brush density and the protein repellent ability. Densely packed PEG surface which showed great protein repellent ability, presented in this study, suggests promising utility as engineered biomaterials including high-throughput screening and clinical diagnostics.

Modification of wood with silicon compounds. Treatment systems based on organic silicon compounds ? a review

A wide variety of organo-silicon compounds has been described for application on wood. Some compounds such as organo-functional silanes which are mostly applied in combination with tetraalkoxysilanes (sol-gel process) as well as chlorosilanes and trimethylsilyl derivatives were proposed for a full impregnation treatment of wood. Other systems have been developed for surface treatment of wood such as plasma coating with hexametyldisiloxane and micro-emulsions which mainly contain silane/siloxane mixtures. The effects related to the various treatments vary from an increase in dimensional stability, durability and fire resistance to an enhanced hydrophobation of wood. In the cases of decay and fire resistance a combination of silicon based systems with other chemicals was required to obtain satisfactory results. Due to the excellent water repellent ability and weathering stability of some treatments, application of silicon treated wood under conditions of hazard class III (EN 335 outside above ground exposure) is recommended.

Olfactory responses of Sitophilus zeamais L. to bushmint leaf powder and methanol extract on stored maize

Bushmint (Hyptis suaveolens Poit) is a weed with pesticidal properties that have been explored in managing pests of agricultural and medicinal importance. The objective of this study was to evaluate the repellence ability of Hyptis suaveolens to prevent infestation of stored maize grain seed. The study involved evaluation of the olfactory responses of adult weevil to maize (Zea mays L.) grains treated with 5, 10, 15 and 20% concentrations of leaf powder (LP) and methanol extract (ME) of Hyptis suaveolens in the laboratory, with a static air four-chamber olfactometer. Also, the insecticidal effects of the substances on adult mortality and oviposition on maize grains treated with LP and ME were determined in a completely randomised design, with four replicates. The number of weevils in ME chambers decreased with increase in concentration of extracts; while the LP chambers had consistently fewer weevils with numbers, ranging from 2.5 to 3.75. Adult mortality in maize treated with LP was the least and varied between 0.00 (15% concentration) and 2.54% (20% concentration). Maize grains with ME caused significant mortalities that ranged from 65.50% at 15% concentration to 94.92% at 10% concentration. More eggs (3.5 to 5.75) were laid on maize with LP compared with ME treated maize. Generally, ME was richer in phytochemicals than LP. Hyptis suaveolens repellence manifested more in the form of LP than as ME; though ME caused more adult mortality and reduced oviposition than LP.