Synthesis of Vapochromic Dyes Having Sensing Properties for Vapor Phase of Organic Solvents Used in Semiconductor Manufacturing Processes and Their Application to Textile-Based Sensors

Two vapochromic dyes (DMx and DM) were synthesized to be used for textile-based sensors detecting the vapor phase of organic solvents. They were designed to show sensitive color change properties at a low concentration of vapors at room temperature. They were applied to cotton fabrics as a substrate of the textile-based sensors to examine their sensing properties for nine organic solvents frequently used in semiconductor manufacturing processes, such as trichloroethylene, dimethylacetamide, iso-propanol, methanol, n-hexane, ethylacetate, benzene, acetone, and hexamethyldisilazane. The textile sensor exhibited strong sensing properties of polar solvents rather than non-polar solvents. In particular, the detection of dimethylacetamide was the best, showing a color difference of 15.9 for DMx and 26.2 for DM under 300 ppm exposure. Even at the low concentration of 10 ppm of dimethylacetamide, the color change values reached 7.7 and 13.6, respectively, in an hour. The maximum absorption wavelength of the textile sensor was shifted from 580 nm to 550 nm for DMx and 550 nm to 540 nm for DM, respectively, due to dimethylacetamide exposure. The sensing mechanism was considered to depend on solvatochromism, the aggregational properties of the dyes and the adsorption amounts of the solvent vapors on the textile substrates to which the dyes were applied. Finally, the reusability of the textile sensor was tested for 10 cycles

Fumigant Activity of Ethyl Formate against the Chestnut Weevil, Curculio sikkimensis Heller

Castanea crenata Siebold & Zucc. (Fagales: Fagaceae), a species of chestnut native to Korea and Japan, is distributed in Korea, Japan, and northeastern China, where chestnuts are a major economic agroforest product. Curculio spp. is among the main known pests of chestnuts around the world. In Korea, only phosphine (PH3) is permitted for the fumigation of C. sikkimensis larva-infested chestnuts. However, it is applied for large-scale fumigation, and its use is restricted. Moreover, it requires a long exposure time and an application device; thus, it cannot be used by small-scale farmers. In this study, the activity of ethyl formate (EF) as a fumigant against Curculio sikkimensis in chestnuts was investigated, and its potential for practical use by farmers was evaluated. The sorption of EF according to the filling ratio (FR) and fumigation time was tested, and the results revealed that 2.5% FR was the most effective. For C. sikkimensis in chestnuts, the mortality rate increased proportionately with the dose of EF. After exposure to 160 g/m3 of EF in a 12 L desiccator, the adult C. sikkimensis showed 100% mortality. According to the time–dose mortality data collected over 12 h of fumigation, the LCT90 and LCT99 values were estimated as 1052.0 and 1952.0 g·h/m3. The results revealed that immersion was not an effective method for controlling C. sikkimensis. According to the LCT values, a dose of 180.0 g/m3 and 12 h of fumigation resulted in 100% mortality on a small scale (2 m3). The results of this experiment indicate that EF could be conveniently used as a fumigant by farmers

Diel Rhythmicity of Field Responses to Synthetic Pheromone Lures in the Pine Sawyer Monochamus saltuarius

The pine wood nematode (PWN), Bursaphelenchus xylophilus, causes lethal pine wilt disease (PWD) in Asia and Europe and has become a serious threat to global pine forest ecosystems. In Korea, Monochamus saltuarius transmits PWN not only to Pinus densiflora, but also to Pinus koraiensis, which is widely distributed across eastern Asia. The diel rhythmicity of M. saltuarius in response to its aggregation pheromone was studied with the aim of providing reliable data for the prevention of PWD and control of Monochamus spp. Using a spray dispenser controlled with an electronic timer, M. saltuarius pheromone and attractants (PA) were sprayed to determine the diel rhythm of the response to PA. The spraying period was divided into four time periods: 05:00–11:00 (time period A), 11:00–17:00 (time period B), 17:00–23:00 (time period C), and 23:00–05:00 (time period D). The largest number of M. saltuarius was caught in time period B, followed by A, C, and D. It could be concluded that the flight activity of M. saltuarius in response to PA was diurnal. The results of this study improve the understanding of the behavioral biology of M. saltuarius, allowing for the development of pest management strategies to prevent the spread of PWN and control its vector

Textile-Based Volatile Organic Compound Sensors Using Cellulose Fabrics and Direct Dyes

In order to fabricate colorimetric textile sensors detecting gas phase of volatile organic compounds (VOCs), 11 kinds of direct dyes were investigated for 13 types of VOCs. Direct Violet 51 was chosen for its best sensing performance both instrumentally and visibly. Direct Violet 51 exhibited the change of color strength and color hue by exposure VOCs. The dyed cotton fabrics detected polar VOCs well, especially N,N-dimethylformamide (DMF). The colorimetric cotton-based textile sensor dyed with Direct Violet 51 exhibited approximately 10 of color difference (ΔE) under 10 ppm DMF gas within 100 min, and the maximum absorption wavelength was shifted from 560 nm to 530 nm. The sensing mechanisms could be summarized in three factors: solvatochromism and aggregative characteristics from the point of view of dye, and adsorption amount of VOCs for fabric. The colorimetric textile sensor retained its sensing performance after 10 cycle tests

Myrtaceae Plant Essential Oils and their β-Triketone Components as Insecticides against Drosophila suzukii

Spotted wing drosophila (SWD, Drosophila suzukii (Matsumura), Diptera: Drosophilidae) is recognized as an economically important pest in North America and Europe as well as in Asia. Assessments were made for fumigant and contact toxicities of six Myrtaceae plant essential oils (EOs) and their components to find new alternative types of insecticides active against SWD. Among the EOs tested, Leptospermum citratum EO, consisting mainly of geranial and neral, exhibited effective fumigant activity. Median lethal dose (LD50; mg/L) values of L. citratum were 2.39 and 3.24 for males and females, respectively. All tested EOs except Kunzea ambigua EO exhibited effective contact toxicity. LD50 (µg/fly) values for contact toxicity of manuka and kanuka were 0.60 and 0.71, respectively, for males and 1.10 and 1.23, respectively, for females. The LD50 values of the other 3 EOs-L. citratum, allspice and clove bud were 2.11–3.31 and 3.53–5.22 for males and females, respectively. The non-polar fraction of manuka and kanuka did not show significant contact toxicity, whereas the polar and triketone fractions, composed of flavesone, isoleptospermone and leptospermone, exhibited efficient activity with the LD50 values of 0.13–0.37 and 0.22–0.57 µg/fly for males and females, respectively. Our results indicate that Myrtaceae plant EOs and their triketone components can be used as alternatives to conventional insecticides

In vitro antibacterial activity and major bioactive components of Cinnamomum verum essential oils against cariogenic bacteria, Streptococcus mutans and Streptococcus sobrinus

Objective: To evaluate the antibacterial activity of Cinnamomum verum (C. verum) from 32 different essential oils against cariogenic bacteria, Streptococcus mutans (S. mutans) and Streptococcus sobrinus (S. sobrinus). Methods: The antibacterial activities of each essential oil were individually investigated against S. mutans and S. sobrinus. The essential oil of C. verum was selected for further evaluation against S. mutans and S. sobrinus. Gas chromatography mass spectrometry was used to determine the major constituents of C. verum essential oil. In addition, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration of the most effective constituent was investigated. Results: The essential oil from C. verum exhibited the greatest antibacterial activity. Gas chromatography mass spectrometry analysis revealed that the major components of C. verum essential oil were cinnamaldehyde (56.3%), cinnamyl acetate (7.1%) and β-phellandrene (6.3%). The MIC of cinnamaldehyde was measured using broth dilution assays. The MIC of cinnamaldehyde was 0.02% (v/v) against both bacterial strains tested. The minimum bactericidal concentration of cinnamaldehyde against S. mutans and S. sobrinus were 0.2% and 0.1% (v/v), respectively. Conclusions: The essential oil of C. verum and its major component cinnamaldehyde possessed considerable in vitro antibacterial activities against cariogenic bacteria, S. mutans and S. sobrinus strains. These results showed that the essential oil of C. verum and its bioactive component, cinnamaldehyde, have potential for application as natural agents for the prevention and treatment of dental caries

Nematicidal Activity of Benzyloxyalkanols against Pine Wood Nematode

Pine wilt disease (PWD) is caused by the pine wood nematode (PWN; Bursaphelenchus xylophilus) and causes severe environmental damage to global pine forest ecosystems. The current strategies used to control PWN are mainly chemical treatments. However, the continuous use of these reagents could result in the development of pesticide-resistant nematodes. Therefore, the present study was undertaken to find potential alternatives to the currently used PWN control agents abamectin and emamectin. Benzyloxyalkanols (BzOROH; R = C2–C9) were synthesized and the nematicidal activity of the synthetic compounds was investigated. Enzymatic inhibitory assays (acetylcholinesterase (AChE) and glutathione S-transferase (GST)) were performed with BzOC8OH and BzOC9OH to understand their mode of action. The benzyloxyalkanols showed higher nematicidal activity than did benzyl alcohol. Among the tested BzOROHs, BzC8OH and BzC9OH showed the strongest nematicidal activity. The LD50 values of BzC8OH and BzC9OH were 246.1 and 158.0 ppm, respectively. No enzyme inhibitory activity was observed for BzC8OH and BzC9OH. The results suggested that benzyloxyalcohols could be an alternative nematicidal agent