Publications by authors named "Hee J Hwang"

Background: The Bradybaenidae snail Karaftohelix adamsi is endemic to Korea, with the species tracked from Island Ulleung in North Gyeongsang Province of South Korea. K. adamsi has been classified under the Endangered Wildlife Class II species of Korea and poses a severe risk of extinction following habitat disturbances.

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The integration of graphene with semiconductor materials has been studied for developing advanced electronic and optoelectronic devices. Here, we propose ultrahigh photoresponsivity of β-GaO photodiodes with a graphene monolayer inserted in a W Schottky contact. After inserting the graphene monolayer, we found a reduction in the leakage current and ideality factor.

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Piezoelectric nanogenerators (PENGs) with molybdenum disulfide (MoS) monolayers have been intensively studied owing to their superior mechanical durability and stability. However, the limited output performance resulting from a small active area and low strain levels continues to pose a significant challenge that should be overcome. Herein, we report a novel strategy for the epoch-making output performance of a PENG with a MoS monolayer by adopting the additive strain concentration concept.

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Background: Ticks are ectoparasites capable of directly damaging their hosts and transmitting vector-borne diseases. The ixodid tick Haemaphysalis flava has a broad distribution that extends from East to South Asia. This tick is a reservoir of severe fever with thrombocytopenia syndrome virus (SFTSV) that causes severe hemorrhagic disease, with cases reported from China, Japan and South Korea.

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Transcriptome studies for conservation of endangered mollusks is a proactive approach towards managing threats and uncertainties facing these species in natural environments. The population of these species is declining due to habitat destruction, illicit wildlife trade, and global climate change. These activities risk the free movement of species across the wild landscape, loss of breeding grounds, and restrictions in displaying the physiological attributes so crucial for faunal welfare.

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Microbial production of valuable bioproducts is a promising route towards green and sustainable manufacturing. The oleaginous yeast, Rhodosporidium toruloides, has emerged as an attractive host for the production of biofuels and bioproducts from lignocellulosic hydrolysates. 3-hydroxypropionic acid (3HP) is an attractive platform molecule that can be used to produce a wide range of commodity chemicals.

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Background: Dung beetles recycle organic matter through the decomposition of feces and support ecological balance. However, these insects are threatened by the indiscriminate use of agrochemicals and habitat destruction. Copris tripartitus Waterhouse (Coleoptera: Scarabaeidae), a dung beetle, is listed as a class-II Korean endangered species.

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3-Hydroxypropionic acid (3-HP) is a valuable platform chemical that is used as a precursor for several higher value-added chemical products. There is an increased interest in development of cell factories as a means for the synthesis of 3-HP and various other platform chemicals. For more than a decade, concentrated effort has been invested by the scientific community towards developing bio-based approaches for the production of 3-HP using primarily and as production hosts.

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One tetraacetylphytosphingosine (TAPS)-producing mutant was obtained by exposing wild-type to γ-ray irradiation. The mutant named 736 produced up to 9.1 g/L of TAPS (218.

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Charonia lampas sauliae (triton snails, triton shells or tritons; Mollusca, Caenogastropoda, Littorinimorpha, Ranellidae) is a marine species with a wide distribution. In Korea, this species is listed as vulnerable and is regionally protected as an endangered species. Here, we report the first comprehensive transcriptome dataset of C.

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Since the first invention of triboelectric nanogenerators (TENGs) in 2012, many mechanical systems have been applied to operate TENGs, but mechanical contact losses such as friction and noise are still big obstacles for improving their output performance and sustainability. Here, we report on a magnet-assembled cam-based TENG (MC-TENG), which has enhanced output power and sustainability by utilizing the non-contact repulsive force between the magnets. We investigate the theoretical and experimental dynamic behaviors of MC-TENGs according to the effects of the contact modes, contact and separation times, and contact forces (i.

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Chemically synthesized retinyl palmitate has been widely used in the cosmetic and biotechnology industry. In this study, we aimed to demonstrate the microbial production of retinyl palmitate and the benefits of microbial retinyl palmitate in skin physiology. A heterologous retinyl palmitate biosynthesis pathway was reconstructed in metabolically engineered using synthetic expression modules from , , and .

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Mechanoreceptors in human skin possess high sensitivity, wide sensing range, and high sensing resolution for external stimuli. Several attempts have been made to implement electronic skin (e-skin) that can mimic human skin. However, previous attempts are limited by the fundamental resolution problem arising from the use of film-like materials generated through pouring and spinning processes.

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Cancer treatments are often more successful when the disease is detected early. We evaluated the feasibility and safety of multicancer blood testing coupled with positron emission tomography-computed tomography (PET-CT) imaging to detect cancer in a prospective, interventional study of 10,006 women not previously known to have cancer. Positive blood tests were independently confirmed by a diagnostic PET-CT, which also localized the cancer.

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Here, a thin and foldable porous reduced graphene oxide (rGO) fabricated by a solvent casting method (SC-rGO) is introduced. The SC-rGO is superior to aluminum as a positive triboelectric material in triboelectric nanogenerators (TENGs), significantly enhancing TENG output performance. The film shows extremely foldable features, where it could be folded by 1/16 size.

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A triboelectric nanogenerator (TENG) is an emerging energy harvesting technology utilizing multi-directional, wasted mechanical energies stemming from vibrations, winds, waves, body movements, etc. In this study, we report a comb-structured TENG (CTENG) capable of effectively scavenging multi-directional motions from human movements, which include walking, jumping, and running. By attaching CTENG to a person's calf, we obtain a root-mean-square (RMS) power value of 5.

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Ambient vibration energy is highly irregular in force and frequency. Triboelectric nanogenerators (TENG) can convert ambient mechanical energy into useable electricity. In order to effectively convert irregular ambient vibrations into electricity, the TENG should be capable of reliably continuous operation despite variability in input forces and frequencies.

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Background: Incilaria (= Meghimatium) fruhstorferi is an air-breathing land slug found in restricted habitats of Japan, Taiwan and selected provinces of South Korea (Jeju, Chuncheon, Busan, and Deokjeokdo). The species is on a decline due to depletion of forest cover, predation by natural enemies, and collection. To facilitate the conservation of the species, it is important to decide on a number of traits related to growth, immunity and reproduction addressing fitness advantage of the species.

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The oxidation of metal microparticles (MPs) in a polymer film yields a mesoporous highly-deformable composite polymer for enhancing performance and creating a gapless structure of triboelectric nanogenerators (TENGs). This is a one-step scalable synthesis for developing large-scale, cost-effective, and light-weight mesoporous polymer composites. We demonstrate mesoporous aluminum oxide (Al₂O₃) polydimethylsiloxane (PDMS) composites with a nano-flake structure on the surface of Al₂O₃ MPs in pores.

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Triboelectric nanogenerators (TENGs) are used as self-power sources for various types of devices by converting external waves, wind, or other mechanical energies into electric power. However, obtaining a high-output performance is still of major concern for many applications. In this study, to enhance the output performance of polydimethylsiloxane (PDMS)-based TENGs, highly dielectric TiO nanoparticles (NPs) were embedded as a function of weight ratio.

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Background: Promoters regulate the expression of metabolic pathway genes to control the flux of metabolism. Therefore, fine-tuning of metabolic pathway gene expression requires an applicable promoter system. In this study, a dissolved oxygen-dependent promoter was engineered for fine-tuning the expression levels of biosynthetic pathway enzymes in .

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The tadpole shrimp ( is an aquatic crustacean that helps control pest populations. It inhabits freshwater ponds and pools and has been described as a living fossil. was officially declared an endangered species South Korea in 2005; however, through subsequent protection and conservation management, it was removed from the endangered species list in 2012.

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The nar promoter, a dissolved oxygen (DO)-dependent promoter in Escherichia coli, is simply induced and functional in any cell growth phase, which are advantageous for producing biochemicals/fuels on an industrial scale. To demonstrate the feasibility of using the nar promoter in the metabolic engineering of biochemicals/biofuels in E. coli, three target pathways were examined: the d-lactate, 2,3-butandiol (2,3-BDO), and 1,3-propanediol (1,3-PDO) pathways consisting of one, three, and six genes, respectively.

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Estrogen-related receptor gamma (ERRγ) has recently been recognized as an attractive target for treating inflammation, cancer, and metabolic disorders. Herein, we discovered and demonstrated the in vitro pharmacology as well as the absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties of chemical entities that could act as highly selective inverse agonists for ERRγ. The results were comparable to those for GSK5182 (4), a leading ERRγ inverse agonist ligand.

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Objectives: To identify the prevalence of osteosarcopenic obesity and to evaluate the association between sarcopenic obesity and bone mineral density in middle-aged and elderly Korean.

Methods: This study included 3,385 males and 4,064 females (age ≥50 years and in the stage of menopause) who participated in the Korean National Health and Nutrition Examination Survey (KNHANES) from 2008 to 2011. The cutoff value for sarcopenia was 7.

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