Wireless chemical sensing schemes using environmentally sensitive hydrogels

In situ sensing of chemical parameters such as pH, glucose, enzymes, and other analytes is of immense importance in health care and environmental monitoring. There has been considerable research in this area using hydrogels as a chemo-mechanical transducer. Hydrogels are water-swollen polymers containing chemical groups that are sensitive to environmental stimuli. When there is a chemical change, e.g. alkali to acidic pH, hydrogel swells or shrinks. This reversible volume change can be coupled to capacitive, inductive or other sensing mechanisms. Despite many years of research, hydrogel-based sensors have not been of practical utility. This has been due to several reasons such as: 1) manipulation difficulties of hydrated gel and their integration with hard inorganic materials, 2) slow response of transducer due to diffusion limited sensing mechanism, 3) baseline and sensitivity drift, and 4) biofouling. In 2006, Ziaie\u27s group presented a wireless MEMS-based pH/glucose sensitive sensor using hydrogel. Despite successful demonstration for a proof of concept, the device had several shortcomings such as a complicated fabrication processes resulting in low yield, difficulty in snugfilling of a small cavity with hydrogel, and slow response time. The doctoral work presented here reports on several investigations undertaken to overcome the aforementioned shortcomings by developing novel, simple to fabricate, and inexpensive methods using 1) immobilized ferrogel (magnetic nanoparticles embedded in hydrogel) on top of an integrated flat coil, 2) hydrogel/polymeric magnet bilayer, and 3) microbubbles embedded hydrogel. The reversible swelling/shrinking of hydrogel results in 1) a change of inductance, which can be wirelessly monitored by standard phase 6 detection methods, 2) vertical movement of a polymeric magnet, which can be remotely detected by a giant magneto resistance (GMR) sensor, and 3) a variation of microbubble-density inside of the hydrogel, which can be evaluated using an ultrasound imaging equipment. The primary engineering contributions of this research includes design, fabrication, and characterization of the systems using pH and glucose sensitive hydrogels

Development of Multi-Functional Molecular Systems for Applications on Nanomaterial Surfaces

The glutathione-mediated, retro Michael-type addition reaction is demonstrated to take place at the interface of water-soluble, maleimide-functionalized gold nanoparticles (Maleimide-AuNP). The retro Michael-type addition can be blocked by hydrolyzing the Michael addition thioether adduct at the nanoparticle’s interface. This procedure “locks” the molecule of interest onto the Maleimide-AuNP template, ensuring no loss of the molecular cargo from the nanocarrier. On the other hand, the glutathione-mediated retro Michael-type addition reaction can be exploited for delivering a molecular payload. The Michael donor, 4-mercaptophenylacetic acid was modified with a terminal azide, allowing for addition of cargo through strain-promoted alkyne azide cycloadditions with various functional alkynes. The resulting AuNPs are versatile platforms for the integration of multiple functionalities within a single construct, enabling their use in complex biotic environments. As a proof of concept, a fluorogenic molecular cargo was incorporated onto a Maleimide-AuNP and delivered via the glutathione-mediated, retro Michael-type addition reaction

Multiclass classification of imagined speech EEG using noise-assisted multivariate empirical mode decomposition and multireceptive field convolutional neural network

IntroductionIn this study, we classified electroencephalography (EEG) data of imagined speech using signal decomposition and multireceptive convolutional neural network. The imagined speech EEG with five vowels /a/, /e/, /i/, /o/, and /u/, and mute (rest) sounds were obtained from ten study participants.Materials and methodsFirst, two different signal decomposition methods were applied for comparison: noise-assisted multivariate empirical mode decomposition and wavelet packet decomposition. Six statistical features were calculated from the decomposed eight sub-frequency bands EEG. Next, all features obtained from each channel of the trial were vectorized and used as the input vector of classifiers. Lastly, EEG was classified using multireceptive field convolutional neural network and several other classifiers for comparison.ResultsWe achieved an average classification rate of 73.09 and up to 80.41% in a multiclass (six classes) setup (Chance: 16.67%). In comparison with various other classifiers, significant improvements for other classifiers were achieved (p-value < 0.05). From the frequency sub-band analysis, high-frequency band regions and the lowest-frequency band region contain more information about imagined vowel EEG data. The misclassification and classification rate of each vowel imaginary EEG was analyzed through a confusion matrix.DiscussionImagined speech EEG can be classified successfully using the proposed signal decomposition method and a convolutional neural network. The proposed classification method for imagined speech EEG can contribute to developing a practical imagined speech-based brain-computer interfaces system

Colloidosomes as a Protocell Model: Engineering Life-Like Behaviour through Organic Chemistry

The bottom-up synthesis of self-assembled micro-compartmentalised systems that mimic basic characteristics of living cells is rapidly evolving. These types of systems are termed “protocells” and can be chemically programmed to grow and divide, to send and receive chemical signals, to transcript and translate chemical information, to adhere to surfaces or to other protocells, and to perform rudimental enzyme-mediated metabolic processes. An emerging protocell model that is attracting great attention is the colloidosome. Colloidosomes are microcapsules with a chemically crosslinked, semipermeable membrane composed of amphiphilic nanoparticles. Colloidosomes display important advantages over other protocell models (e. g., vesicles and coacervate micro-droplets) due to their physical-chemical properties that can be easily tuned through the careful engineering of their synthetic building blocks. In this review, we deliver an overview of the different types of colloidosomes that have been developed thus far and discuss how organic chemistry contributes to the design and bottom-up synthesis of novel types of colloidosomes endowed with advanced chemically programmed bio-inspired functions

Proto-type installation of a double-station system for the optical-video-detection and orbital characterisation of a meteor/fireball in South Korea

We give a detailed description of the installation and operation of a double-station meteor detection system which formed part of a research & education project between Korea Astronomy Space Science Institute and Daejeon Science Highschool. A total of six light-sensitive CCD cameras were installed with three cameras at SOAO and three cameras at BOAO observatory. A double-station observation of a meteor event enables the determination of the three-dimensional orbit in space. This project was initiated in response to the Jinju fireball event in March 2014. The cameras were installed in October/November 2014. The two stations are identical in hardware as well as software. Each station employes sensitive Watec-902H2 cameras in combination with relatively fast f/1.2 lenses. Various fields of views were used for measuring differences in detection rates of meteor events. We employed the SonotaCo UFO software suite for meteor detection and their subsequent analysis. The system setup as well as installation/operation experience is described and first results are presented. We also give a brief overview of historic as well as recent meteor (fall) detections in South Korea. For more information please consult http://meteor.kasi.re.kr .Comment: Technical/instrumentation description of a professional meteor detection system, 23 pages, 20 figures (color/monochrome), 5 tables, submitted to the Journal of Korean Astronomical Society (JKAS, http://jkas.kas.org/, http://jkas.kas.org/history.html

Idh2

Acrolein is known to be involved in acute lung injury and other pulmonary diseases. A number of studies have suggested that acrolein-induced toxic effects are associated with depletion of antioxidants, such as reduced glutathione and protein thiols, and production of reactive oxygen species. Mitochondrial NADP+-dependent isocitrate dehydrogenase (idh2) regulates mitochondrial redox balance and reduces oxidative stress-induced cell injury via generation of NADPH. Therefore, we evaluated the role of idh2 in acrolein-induced lung injury using idh2 short hairpin RNA- (shRNA-) transfected Lewis lung carcinoma (LLC) cells and idh2-deficient (idh2−/−) mice. Downregulation of idh2 expression increased susceptibility to acrolein via induction of apoptotic cell death due to elevated mitochondrial oxidative stress. Idh2 deficiency also promoted acrolein-induced lung injury in idh2 knockout mice through the disruption of mitochondrial redox status. In addition, acrolein-induced toxicity in idh2 shRNA-transfected LLC cells and in idh2 knockout mice was ameliorated by the antioxidant, N-acetylcysteine, through attenuation of oxidative stress resulting from idh2 deficiency. In conclusion, idh2 deficiency leads to mitochondrial redox environment deterioration, which causes acrolein-mediated apoptosis of LLC cells and acrolein-induced lung injury in idh2−/− mice. The present study supports the central role of idh2 deficiency in inducing oxidative stress resulting from acrolein-induced disruption of mitochondrial redox status in the lung