Biobased production of alkanes and alkenes through metabolic engineering of microorganisms

Advancement in metabolic engineering of microorganisms has enabled bio-based production of a range of chemicals, and such engineered microorganism can be used for sustainable production leading to reduced carbon dioxide emission there. One area that has attained much interest is microbial hydrocarbon biosynthesis, and in particular, alkanes and alkenes are important high-value chemicals as they can be utilized for a broad range of industrial purposes as well as 'drop-in' biofuels. Some microorganisms have the ability to biosynthesize alkanes and alkenes naturally, but their production level is extremely low. Therefore, there have been various attempts to recruit other microbial cell factories for production of alkanes and alkenes by applying metabolic engineering strategies. Here we review different pathways and involved enzymes for alkane and alkene production and discuss bottlenecks and possible solutions to accomplish industrial level production of these chemicals by microbial fermentation

Non-decimated wavelet transform in statistical assessment of scaling: Theory and applications

In this thesis, we introduced four novel methods that facilitate the scaling estimation based on NDWT. Chapter 2 introduced an NDWT matrix which is used to perform an NDWT in one or two dimensions. The use of matrix significantly decreased the computation time when 2-D inputs of moderate size are transformed under MATLAB environment, and such reduction of computation time was augmented when the same type of NDWT is performed repeatedly. With 2-D inputs, an NDWT matrix yielded a scale-mixing NDWT, which is more compressive than the standard 2-D NDWT. The retrieval of an original signal after the transform was possible with a weight matrix. An NDWT matrix can handle signals of non-dyadic sizes in one or two dimensions. The proposed NDWT matrix was used for the transforms in Chapters 3-5. Chapter 3 introduced a method for scaling estimation based on a non-decimated wavelet spectrum. A distinctive feature of NDWT, redundancy, enables us to obtain local spectra and improves the accuracy of scaling estimation. For simulated signals with known $H$ values, the method yields estimators of $H$ with lower mean squared errors. We characterized mammographic images with the proposed scaling estimator and anisotropy measures from non-decimated wavelet spectra for breast cancer detection, and obtained the best diagnostic accuracy in excess of 80\%. Some real-life signals are known to possess a theoretical value of the Hurst exponent. Chapter 4 described a Bayesian scaling estimation method that utilizes the value of a theoretical scaling index as a mean of prior distribution and estimates $H$ with MAP estimation. The accuracy of estimators from the proposed method is robust to small misspecification of the prior mean. We applied the method to a turbulence velocity signal and yielded an estimator of $H$ close to the theoretical value. Chapter 5 proposed two methods based on NDWT for robust estimation of Hurst exponent $H$ of 1-D self-similar signals. The redundancy of NDWT, which improved the accuracy of estimation, introduced autocorrelations within the wavelet coefficients. With the two proposed methods, we alleviated the autocorrelation in three ways: taking the logarithm prior to taking the median, relating Hurst exponent to the median instead of mean of the model distribution, and resampling the coefficients.Ph.D

Case Study on the Enterprise Microblog Usage: Focusing on Knowledge Learning

Knowledge Management Strategy can be classified by codification strategy and personalization strategy (Hansen et. al., 1999), and how to manage the two strategies were always studied. Also, current studies regarding the knowledge management strategy were targeted mostly for major companies, resulting in lack of studies in how it can be applied on SMEs. This research, with the knowledge management strategy suited for SMEs, sets an Enterprise Microblog (EMB), and with the EMB applied on SMEs’ Knowledge Management Strategy, it is reviewed on the perspective of SMEs’ Codification and Personalization Strategies. Through the advanced research regarding Knowledge Management Strategy and EMB, the hypothesis is set that “Depending on the development of the company, the main application of EMB alters from Codification Strategy to Personalization Strategy.” To check the hypothesis, SME that have used the EMB called ‘Yammer’ was analyzed from the data of their foundation until today. The case study has implemented longitudinal analysis which divides the period when the EMBs were used into three stages and analyzes the contents. As the result of the study, this suggests a substantial implication regarding the application of Knowledge Management Strategy and its Knowledge Management System that is suitable for SME

Generalizations of -Subalgebras in BCK/BCI-Algebras Based on Point -Structures

The aim of this article is to obtain more general forms than the papers of (Jun et al. (2010); Jun et al. (in press)). The notions of -subalgebras of types , and are introduced, and the concepts of -support and -support are also introduced. Several related properties are investigated. Characterizations of -subalgebra of type are discussed, and conditions for an -subalgebra of type to be an -subalgebra of type are considered

Functional screening of aldehyde decarbonylases for long-chain alkane production by Saccharomyces cerevisiae

Background: Low catalytic activities of pathway enzymes are often a limitation when using microbial based chemical production. Recent studies indicated that the enzyme activity of aldehyde decarbonylase (AD) is a critical bottleneck for alkane biosynthesis in Saccharomyces cerevisiae. We therefore performed functional screening to identify efficient ADs that can improve alkane production by S. cerevisiae

The role of social support and social networks in smoking behavior among middle and older aged people in rural areas of South Korea: A cross-sectional study

<p>Abstract</p> <p>Background</p> <p>Although the number of studies on anti-smoking interventions has increased, studies focused on identifying social contextual factors in rural areas are scarce. The purpose of this study was to explore the role of social support and social networks in smoking behavior among middle and older aged people living in rural areas of South Korea.</p> <p>Methods</p> <p>The study employed a cross-sectional design. Participants included 1,057 adults, with a mean age of 60.7 years, residing in rural areas. Information on participants' tobacco use, stress, social support, and social networks was collected using structured questionnaires. The chi-square test, the t-test, ANOVA, and logistic regression were used for data analysis.</p> <p>Results</p> <p>The overall smoking prevalence in the study was 17.4% (men, 38.8%; women, 5.1%). Overall, stress was high among women, and social support was high among men. Smokers had high levels of social support (t = -2.90, p = .0038) and social networks (t = -2.22, p = .0271), as compared to non- and former smokers. Those in the high social support group were likely to be smokers (AOR = 2.21, 95% CI 1.15-4.26). Women with moderate social ties were less likely to smoke (AOR = 0.18, 95% CI 0.05-0.61).</p> <p>Conclusion</p> <p>There was a protective role of a moderate social network level among women, and a high level of social support was associated with smoking behaviors in rural areas. Findings suggest the need for a comprehensive understanding of the functions and characteristics of social contextual factors including social support and social networks in order to conduct more effective anti-smoking interventions in rural areas.</p

Metal work-function-dependent barrier height of Ni contacts with metal-embedded nanoparticles to 4H-SiC

Metal, typically gold [Au], nanoparticles [NPs] embedded in a capping metal contact layer onto silicon carbide [SiC] are considered to have practical applications in changing the barrier height of the original contacts. Here, we demonstrate the use of silver [Ag] NPs to effectively lower the barrier height of the electrical contacts to 4H-SiC. It has been shown that the barrier height of the fabricated SiC diode structures (Ni with embedded Ag-NPs) has significantly reduced by 0.11 eV and 0.18 eV with respect to the samples with Au-NPs and the reference samples, respectively. The experimental results have also been compared with both an analytic model based on Tung's theory and physics-based two-dimensional numerical simulations

Association of plasma amyloid-β oligomerization with theta/beta ratio in older adults

BackgroundOligomeric Aβ (OAβ) is a promising candidate marker for Alzheimer’s disease (AD) diagnosis. Electroencephalography (EEG) is a potential tool for early detection of AD. Still, whether EEG power ratios, particularly the theta/alpha ratio (TAR) and theta/beta ratio (TBR), reflect Aβ burden—a primary mechanism underlying cognitive impairment and AD. This study investigated the association of TAR and TBR with amyloid burden in older adults based on MDS-OAβ levels.Methods529 individuals (aged ≥60 years) were recruited. All participants underwent EEG (MINDD SCAN, Ybrain Inc., South Korea) and AlzOn™ test (PeopleBio Inc., Gyeonggi-do, Republic of Korea) for quantifying MDS-OAβ values in the plasma. EEG variables were log-transformed to normalize the data distribution. Using the MDS-OAβ cutoff value (0.78 ng/mL), all participants were classified into two groups: high MDS-OAβ and low MDS-OAβ.ResultsParticipants with high MDS-OAβ levels had significantly higher TARs and TBRs than those with low MDS-OAβ levels. The log-transformed TBRs in the central lobe (β = 0.161, p = 0.0026), frontal lobe (β = 0.145, p = 0.0044), parietal lobe (β = 0.166, p = 0.0028), occipital lobe (β = 0.158, p = 0.0058), and temporal lobe (beta = 0.162, p = 0.0042) were significantly and positively associated with increases in MDS-OAβ levels. After adjusting for the Bonferroni correction, the TBRs in all lobe regions, except the occipital lobe, were significantly associated with increased MDS-OAβ levels.ConclusionWe found a significant association of MDS-OAβ with TBR in older adults. This finding indicates that an increase in amyloid burden may be associated with an increase in the low-frequency band and a decrease in the relatively high-frequency band

Non-invasive cortical stimulation improves post-stroke attention decline

Purpose: Attention decline after stroke is common and hampers the rehabilitation process, and non-invasive transcranial direct current stimulation (tDCS) has the potential to elicit behavioral changes by modulating cortical excitability. The authors tested the hypothesis that a single session of non-invasive cortical stimulation with excitatory anodal tDCS applied to the left dorsolateral prefrontal cortex (DLPFC) can improve attention in stroke patients. Methods: Ten patients with post-stroke cognitive decline (MMSE 0.05). Changes in reaction times were comparable for the two stimulations (P > 0.05). Conclusion: Non invasive anodal tDCS applied to the left DLPFC was found to improve attention versus sham stimulation in stroke patients, which suggests that non-invasive cortical intervention could potentially be used during rehabilitative training to improve attention.This research was supported by a grant from Seoul National University College of Medicine (Grant No. 800-20060236) to N.J. Paik, and by a grant from the Korean Geriatric Society to E.K. Kang.Monti A, 2008, J NEUROL NEUROSUR PS, V79, P451, DOI 10.1136/jnnp.2007.135277Priori A, 2008, CEREB CORTEX, V18, P451, DOI 10.1093/cercor/bhm088Kuo MF, 2008, NEUROPSYCHOLOGIA, V46, P2122, DOI 10.1016/j.neuropsychologia.2008.02.023Coulthard E, 2006, CURR OPIN NEUROL, V19, P613Boggio PS, 2006, J NEUROL SCI, V249, P31, DOI 10.1016/j.jns.2006.05.062Gandiga PC, 2006, CLIN NEUROPHYSIOL, V117, P845, DOI 10.1016/j.clinph.2005.12.003Fregni F, 2005, EXP BRAIN RES, V166, P23, DOI 10.1007/s00221-005-2334-6Hummel F, 2005, BRAIN, V128, P490, DOI 10.1093/brain/awh369DEVINSKY O, 2004, NEUROLOGY COGNITIVENitsche MA, 2003, J COGNITIVE NEUROSCI, V15, P619, DOI 10.1162/089892903321662994McDowd JM, 2003, J GERONTOL B-PSYCHOL, V58, pP45Hikosaka O, 2002, CURR OPIN NEUROBIOL, V12, P217Aranda D, 2001, REV NEUROLOGIA, V32, P10Nitsche MA, 2000, J PHYSIOL-LONDON, V527, P633McNevin NH, 2000, PHYS THER, V80, P373DESPOSITO M, 1998, BRAIN RES COGN BRAIN, V7, P1TATEMICHI TK, 1994, J NEUROL NEUROSUR PS, V57, P202