Nature driven spider silk as high energy conversion efficient bio-piezoelectric nanogenerator

Karan, Sumanta Kumar,Maiti, Sandip,Kwon, Owoong,Paria, Sarbaranjan,Maitra, Anirban,Si, Suman Kumar,Kim, Yunseok,Kim, Jin Kon,Khatua, Bhanu Bhusan Elsevier 2018 Nano energy Vol.49 No.-

<P><B>Abstract</B></P> <P>Spider silk fibers having remarkable protein sequence structure contain nature's most outstanding mechanical properties and unrivalled elasticity along with biocompatibility and biodegradability. Unfortunately, it remains completely unidentified how the mechanical properties of spider silk effectively contribute to the performance and integrity on piezoelectric nanogenerator. Here, using piezoresponse force microscopy (PFM), we report for the first time structure-dependent piezoelectric response of the spider silk at the molecular level and confirm that silk fiber shows vertical (or out of the plane) piezoelectric coefficient of up to ~ 0.36 pm/V. We also design a mechanically robust piezoelectric nanogenerator (PNG) using nature driven spider silk that exhibits high energy conversion efficiency (≈ 66%), high output voltage (≈ 21.3 V) and current (≈ 0.68 μA) with instantaneous power density of ≈ 4.56 μW/cm<SUP>2</SUP>. The fabricated device is biocompatible and ultra-sensitive towards physiological signal monitoring such as arterial pulse response which can be useful for potential biomedical applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Spider-silk (SS) shows vertical piezoelectric coefficient (≈ 0.36 pm/V) as confirmed by PFM. </LI> <LI> Nature driven spider silk as an effective bio-piezoelectric nanogenerator (SSBPNG). </LI> <LI> SSBPNG shows power density (≈ 4.56 μW/cm<SUP>2</SUP>) and energy conversion efficiency (≈ 66%). </LI> <LI> Multiple devices in series connection can generate 65 V and turn on 55 LEDs. </LI> <LI> One-dimensional (1D) wire type SSBPNG could be as a promising textile nanogenerator. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P> <B>This study provides an in-depth insight of naturally abundant spider silk as bio-piezoelectric material.</B> We have successfully shown that spider silk has a definite vertical piezoelectric coefficient (∼ 0.36 pm/V) through PFM experiment which is newly added information to the existing piezoelectric history on silk. The fabricated energy harvester with energy conversion efficiency of ≈ 66%, reveals high output performance with instantaneous power density of ≈ 4.56 μW/cm<SUP>2</SUP>.</P> <P>[DISPLAY OMISSION]</P>

The Relationships among Sex, Gender Identity Factors, and Career-Decision-Situation -Specified Pesonality Traits

Ji-Hyeon Kim,Orville Karan 서울대학교 교육연구소 2004 Asia Pacific Education Review Vol.5 No.1

The present study revealed that gender identity involved the integration of various gender identity factors as suggested by Spence (1993) and that career-decision-situation-specified personality variables could be classified into higher order personality trait dimensions as suggested by Tellegen (1985). The results also indicate that the pattern of the relationships found in this study among masculine personality traits, feminine personality traits, and career-decision-situation-specified personality variables reflecting higher-order personality trait dimensions of Tellegen’s (1985) model was similar to that of the relationships among masculine personality traits, feminine personality traits, and general personality traits reflecting higher-order personality trait dimensions in Lubinsky, Tellegen, and Butcher’s (1981, 1983) studies. Multiple regression analyses showed that the addition of a gender identity role attitude factor and a gender identity behavioral interest factor to sex and a gender identity personality trait factor did not improve significantly the prediction of the career-decision-situation-specified personality variables.

Substrate Spectrum Extension of PenA in Burkholderia thailandensis with a Single Amino Acid Deletion, Glu168del

Yi, Hyojeong,Kim, Karan,Cho, Kwang-Hwi,Jung, Oksung,Kim, Heenam Stanley American Society for Microbiology 2012 Antimicrobial Agents and Chemotherapy Vol.56 No.7

<B>ABSTRACT</B><P>We describe a deletion mutation in a class A β-lactamase, PenA, ofBurkholderia thailandensisthat extended the substrate spectrum of the enzyme to include ceftazidime. Glu168del was located in a functional domain called the omega loop causing expansion of the space in the loop, which in turn increased flexibility at the active site. This deletion mutation represents a rare but significant alternative mechanical path to substrate spectrum extension in PenA besides more common substitution mutations.</P>

Bio-waste onion skin as an innovative nature-driven piezoelectric material with high energy conversion efficiency

Maiti, Sandip,Kumar Karan, Sumanta,Lee, Juhyun,Kumar Mishra, Avnish,Bhusan Khatua, Bhanu,Kon Kim, Jin Elsevier 2017 Nano energy Vol.42 No.-

<P><B>Abstract</B></P> <P>Development of non-toxic, ultra-sensitive, and flexible bio-inspired piezoelectric nanogenerator has become a great challenge for next generation biomedical applications. High performance organic/inorganic materials based piezoelectric nanogenerators suffer from several unavoidable problems such as complex synthesis and high toxicity. Biodegradable and biocompatible piezoelectric material is utmost needed in in-vivo condition to harvest energy for biomedical applications. Here, we report a novel bio-piezoelectric nanogenerator (BPNG) using naturally abundant self-aligned cellulose fibrous untreated onion skin (OS) as efficient piezoelectric material having piezoelectric strength of ∼ 2.8 pC/N. The fabricated OSBPNG generated output voltage, current, instantaneous power density and high piezoelectric energy conversion efficiency of ≈ 18V, ≈ 166nA, ≈ 1.7μW/cm<SUP>2</SUP>, and ≈ 61.7%, respectively, and turn on 30 green LEDs by a single device under repeated compressive stress of ≈ 34kPa and ≈ 3.0Hz frequency. In addition, maximum output voltage (≈ 106V) was achieved when 6 units are connected in series, which instantaneously turns on 73 combined LEDs (30 green, 25 blue, and 18 red). OSBPNG is highly effective during throat movement such as coughing, drinking and swallowing. Furthermore, because it works at very low pressure originating from heart pulse or beat, it could be used in pacemakers and health care units. Finally, OSBPNG successfully differentiates speech signals, indicating its potential for speech recognition.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Novel homespun approach for bio-piezoelectric nanogenerator (OSBPNG) using onion skin. </LI> <LI> Plant materials are more useful than living creatures in both handling and supply. </LI> <LI> It works at low pressure even from heart pulse, that can be used in health care unit. </LI> <LI> OSBPNG shows output voltage of 18 V with high energy conversion efficiency (61.7%). </LI> <LI> Maximum output voltage (106 V) achieved by assembling 6 units, which turn on 73 LEDs. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Naturally driven bio-waste and biocompatible onion skin base piezoelectric nanogenerator with high output performance (output voltage and area power density of ≈ 18V, and ≈ 1.7μW/cm<SUP>2</SUP>) and high energy conversion efficiency (≈ 61.7%) has been fabricated through simple homespun device fabrication method. More details on the materials and application can be found in the manuscript.</P> <P>[DISPLAY OMISSION]</P>

Prevalence of Possible Depression and Post-traumatic Stress Disorder among Community Dwelling Adult Refugees and Refugee Applicants in South Korea

손지훈,임진,이종석,Karan Kim,임수연,변나현,김동우,김계형,김민선,조성준,서화연,박지은,권용진,권준수,Curie Ahn 대한의학회 2019 Journal of Korean medical science Vol.34 No.11

Background: Because there has been a recent increase in refugee applications in Korea, the mental health of these refugees merits greater study. Methods: We surveyed 129 refugees (including those in process of refugee application) and 121 migrant workers living in urban communities, using: the Patient Health Questionnaire-9 for depressive symptoms, the Impact Event Scale-Revised for post-traumatic stress disorder (PTSD) symptoms, and the health questionnaires used in 2016 Korean National Health and Nutrition Examination Survey (KNHANES). The majority of refugee subjects were from sub-Saharan Africa and Middle East. We compared the prevalence of possible depression and possible PTSD between refugees and migrant workers and refugees and age-gender matched samples from the KNHANES 2016. Results: Frequency of suicidal planning during the last year was higher in the refugee group than Korean nationals, but frequency of suicidal attempt was not. High risk drinking was found in 0.8% of refugees, 6.6% of migrant workers and 27.2% of Korean nationals. Possible depression was present in 42.9% of refugee subjects, 33.3% of migrant workers, and 4.2% of Korean controls. Possible PTSD was present in 38.9% of refugees compared to 12.5% of migrant workers. Only major risk factor for depression among refugees was a traumatic event before entering Korea. Conclusion: Possible depression and PTSD are significantly more prevalent in refugees, compared to both migrant workers and Korean nationals. Prevalence rates are commensurate with refugee studies worldwide. Appropriate early screening and intervention schemes need to be developed for refugees entering Korea.

A community computational challenge to predict the activity of pairs of compounds

Bansal, Mukesh,Yang, Jichen,Karan, Charles,Menden, Michael P,Costello, James C,Tang, Hao,Xiao, Guanghua,Li, Yajuan,Allen, Jeffrey,Zhong, Rui,Chen, Beibei,Kim, Minsoo,Wang, Tao,Heiser, Laura M,Realubit Nature Publishing Group, a division of Macmillan P 2014 Nature biotechnology Vol.32 No.12

Recent therapeutic successes have renewed interest in drug combinations, but experimental screening approaches are costly and often identify only small numbers of synergistic combinations. The DREAM consortium launched an open challenge to foster the development of in silico methods to computationally rank 91 compound pairs, from the most synergistic to the most antagonistic, based on gene-expression profiles of human B cells treated with individual compounds at multiple time points and concentrations. Using scoring metrics based on experimental dose-response curves, we assessed 32 methods (31 community-generated approaches and SynGen), four of which performed significantly better than random guessing. We highlight similarities between the methods. Although the accuracy of predictions was not optimal, we find that computational prediction of compound-pair activity is possible, and that community challenges can be useful to advance the field of in silico compound-synergy prediction.

Key amino acid residues conferring enhanced enzyme activity at cold temperatures in an Antarctic polyextremophilic β-galactosidase

Laye, Victoria J.,Karan, Ram,Kim, Jong-Myoung,Pecher, Wolf T.,DasSarma, Priya,DasSarma, Shiladitya National Academy of Sciences 2017 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.114 No.47

<P><B>Significance</B></P><P>Combining comparative genomics, mutagenesis, kinetic analysis, and molecular modeling provides a powerful way to explore and understand the structure and function of proteins under extreme and potentially astrobiological conditions. Alignment of closely related cold-active and mesophilic β-galactosidase enzymes from halophilic Archaea, followed by mutagenesis and kinetic analysis, demonstrates the importance of specific amino acid residues in temperature-dependent catalytic activity, while molecular modeling provides a structural framework for their mechanism of action. Such an interdisciplinary approach shows how a very small fraction of conserved residues that are divergent from mesophilic homologs are key to enhancing catalytic activity at cold temperatures and underscores the power of combining genomics and genetics with biochemistry and structural biology for understanding polyextremophilic enzyme function.</P><P>The Antarctic microorganism <I>Halorubrum lacusprofundi</I> harbors a model polyextremophilic β-galactosidase that functions in cold, hypersaline conditions. Six amino acid residues potentially important for cold activity were identified by comparative genomics and substituted with evolutionarily conserved residues (N251D, A263S, I299L, F387L, I476V, and V482L) in closely related homologs from mesophilic haloarchaea. Using a homology model, four residues (N251, A263, I299, and F387) were located in the TIM barrel around the active site in domain A, and two residues (I476 and V482) were within coiled or β-sheet regions in domain B distant to the active site. Site-directed mutagenesis was performed by partial gene synthesis, and enzymes were overproduced from the cold-inducible <I>csp</I>D2 promoter in the genetically tractable Haloarchaeon, <I>Halobacterium</I> sp. NRC-1. Purified enzymes were characterized by steady-state kinetic analysis at temperatures from 0 to 25 °C using the chromogenic substrate <I>o</I>-nitrophenyl-β-galactoside. All substitutions resulted in altered temperature activity profiles compared with wild type, with five of the six clearly exhibiting reduced catalytic efficiency (<I>k</I><SUB>cat</SUB>/<I>K</I><SUB>m</SUB>) at colder temperatures and/or higher efficiency at warmer temperatures. These results could be accounted for by temperature-dependent changes in both <I>K</I><SUB>m</SUB> and <I>k</I><SUB>cat</SUB> (three substitutions) or either <I>K</I><SUB>m</SUB> or <I>k</I><SUB>cat</SUB> (one substitution each). The effects were correlated with perturbation of charge, hydrogen bonding, or packing, likely affecting the temperature-dependent flexibility and function of the enzyme. Our interdisciplinary approach, incorporating comparative genomics, mutagenesis, enzyme kinetics, and modeling, has shown that divergence of a very small number of amino acid residues can account for the cold temperature function of a polyextremophilic enzyme.</P>

High-resolution metabolomics of occupational exposure to trichloroethylene

Walker, Douglas I,Uppal, Karan,Zhang, Luoping,Vermeulen, Roel,Smith, Martyn,Hu, Wei,Purdue, Mark P,Tang, Xiaojiang,Reiss, Boris,Kim, Sungkyoon,Li, Laiyu,Huang, Hanlin,Pennell, Kurt D,Jones, Dean P,Rot Oxford University Press 2016 International journal of epidemiology Vol.45 No.5

<P><B>Background:</B> Occupational exposure to trichloroethylene (TCE) has been linked to adverse health outcomes including non-Hodgkin’s lymphoma and kidney and liver cancer; however, TCE’s mode of action for development of these diseases in humans is not well understood.</P><P><B>Methods:</B> Non-targeted metabolomics analysis of plasma obtained from 80 TCE-exposed workers [full shift exposure range of 0.4 to 230 parts-per-million of air (ppm<SUB>a</SUB>)] and 95 matched controls were completed by ultra-high resolution mass spectrometry. Biological response to TCE exposure was determined using a metabolome-wide association study (MWAS) framework, with metabolic changes and plasma TCE metabolites evaluated by dose-response and pathway enrichment. Biological perturbations were then linked to immunological, renal and exposure molecular markers measured in the same population.</P><P><B>Results:</B> Metabolic features associated with TCE exposure included known TCE metabolites, unidentifiable chlorinated compounds and endogenous metabolites. Exposure resulted in a systemic response in endogenous metabolism, including disruption in purine catabolism and decreases in sulphur amino acid and bile acid biosynthesis pathways. Metabolite associations with TCE exposure included uric acid (<I>β</I> = 0.13, <I>P</I>-value = 3.6 × 10<SUP>−5</SUP>), glutamine (<I>β</I> = 0.08, <I>P</I>-value = 0.0013), cystine (<I>β</I> = 0.75, <I>P</I>-value = 0.0022), methylthioadenosine (<I>β</I> = −1.6, <I>P</I>-value = 0.0043), taurine (<I>β</I> = −2.4, <I>P</I>-value = 0.0011) and chenodeoxycholic acid (<I>β</I> = −1.3, <I>P</I>-value = 0.0039), which are consistent with known toxic effects of TCE, including immunosuppression, hepatotoxicity and nephrotoxicity. Correlation with additional exposure markers and physiological endpoints supported known disease associations.</P><P><B>Conclusions:</B> High-resolution metabolomics correlates measured occupational exposure to internal dose and metabolic response, providing insight into molecular mechanisms of exposure-related disease aetiology.</P>

The Tandem Repeats Enabling Reversible Switching between the Two Phases of β-Lactamase Substrate Spectrum

Yi, Hyojeong,Song, Han,Hwang, Junghyun,Kim, Karan,Nierman, William C.,Kim, Heenam Stanley Public Library of Science 2014 PLoS genetics Vol.10 No.9

<P>Expansion or shrinkage of existing tandem repeats (TRs) associated with various biological processes has been actively studied in both prokaryotic and eukaryotic genomes, while their origin and biological implications remain mostly unknown. Here we describe various duplications (<I>de novo</I> TRs) that occurred in the coding region of a β-lactamase gene, where a conserved structure called the omega loop is encoded. These duplications that occurred under selection using ceftazidime conferred substrate spectrum extension to include the antibiotic. Under selective pressure with one of the original substrates (amoxicillin), a high level of reversion occurred in the mutant β-lactamase genes completing a cycle back to the original substrate spectrum. The <I>de novo</I> TRs coupled with reversion makes a genetic toggling mechanism enabling reversible switching between the two phases of the substrate spectrum of β-lactamases. This toggle exemplifies the effective adaptation of <I>de novo</I> TRs for enhanced bacterial survival. We found pairs of direct repeats that mediated the DNA duplication (TR formation). In addition, we found different duos of sequences that mediated the DNA duplication. These novel elements—that we named SCSs (same-strand complementary sequences)—were also found associated with β-lactamase TR mutations from clinical isolates. Both direct repeats and SCSs had a high correlation with TRs in diverse bacterial genomes throughout the major phylogenetic lineages, suggesting that they comprise a fundamental mechanism shaping the bacterial evolution.</P><P><B>Author Summary</B></P><P>β-lactamases can adapt to new antibiotics by mutations in their genes. The original and the extended substrate spectrums of β-lactamases define two phases of catalytic activity, and the conversion by point mutations is unidirectional from the initial to the new spectrum. We describe duplication mutations that enable reversible switching between the substrate spectrums, increasing the adaptability of the bacterium. We provide evidence supporting that two distinct groups of short sequences mediated the formation of DNA duplications in β-lactamases: direct repeats and novel elements that we named, SCSs (same-strand complementary sequences). Our study suggests that DNA duplication processes mediated by both direct repeats and SCSs are not just limited to the β-lactamase genes but comprise a fundamental mechanism in bacterial genome evolution.</P>

Bioactive Compound Screen for Pharmacological Enhancers of Apolipoprotein E in Primary Human Astrocytes

Finan, G.M.,Realubit, R.,Chung, S.,Lutjohann, D.,Wang, N.,Cirrito, J.R.,Karan, C.,Kim, T.W. Elsevier 2016 Cell chemical biology Vol.23 No.12

<P>Pharmacological screening in physiologically relevant brain cells is crucial for identifying neuroactive compounds that better translate into in vivo biology and efficacious therapeutics. Pharmacological enhancement of apolipoprotein E (apoE), a cholesterol-transporting apolipoprotein, has been proposed as a promising therapeutic approach for Alzheimer's disease. Several nuclear receptor agonists were initially shown to increase brain apoE levels together with ATP-binding cassette transporter 1 (ABCA1), but their underlying mechanisms remain unclear. To gain an insight on brain apoE regulation, we performed an unbiased high-throughput screening of known drugs and bioactive compounds in cultured human primary astrocytes, the major apoE-producing cell type in the brain. We have identified several small molecules that increase apoE secretion via previously unknown mechanisms, including those not co-inducing ABCA1. These newly identified compounds are active preferentially in human astrocytes but not in an astrocytoma cell line, furnishing new tools for investigating biological pathways underlying brain apoE production.</P>