Surface characterization of biomass by imaging mass spectrometry

Lignocellulosic biomass (e.g., non food-based agricultural resides and forestry wastes) has recently been promoted for use as a source of bioethanol instead of food-based materials (e.g., corn and sugar cane), however to fully realize these benefits an improved understanding of lignocellulosic recalcitrance must be developed. The primary goal of this thesis is to gain fundamental knowledge about the surface of the plant cell wall, which is to be integrated into understanding biomass recalcitrance. Imaging mass spectrometry by TOF-SIMS and MALDI-IMS is applied to understand detailed spatial and lateral changes of major components in the surface of biomass under submicron scale. Using TOF-SIMS analysis, we have demonstrated a dilute acid pretreated poplar stem represented chemical differences between surface and bulk compositions. Especially, abundance of xylan was observed on the surface while sugar profile data showed most xylan (ca. 90%) removed from the bulk composition. Water only flowthrough pretreated poplar also represented difference chemistry between surface and bulk, which more cellulose revealed on the surface compared to bulk composition. In order to gain the spatial chemical distribution of biomass, 3-dimensional (3D) analysis of biomass using TOF-SIMS has been firstly introduced in the specific application of understanding recalcitrance. MALDI-IMS was also applied to visualize different molecular weight (e.g., DP) of cellulose oligomers on the surface of biomass.PhDCommittee Chair: Art J. Ragauskas, Advisor; Committee Member: Charles L. Liotta; Committee Member: David M. Collard; Committee Member: Stefan France; Committee Member: Yulin Den

How chip size impacts steam pretreatment effectiveness for biological conversion of poplar wood into fermentable sugars

Background Woody biomass is highly recalcitrant to enzymatic sugar release and often requires significant size reduction and severe pretreatments to achieve economically viable sugar yields in biological production of sustainable fuels and chemicals. However, because mechanical size reduction of woody biomass can consume significant amounts of energy, it is desirable to minimize size reduction and instead pretreat larger wood chips prior to biological conversion. To date, however, most laboratory research has been performed on materials that are significantly smaller than applicable in a commercial setting. As a result, there is a limited understanding of the effects that larger biomass particle size has on the effectiveness of steam explosion pretreatment and subsequent enzymatic hydrolysis of wood chips. Results To address these concerns, novel downscaled analysis and high throughput pretreatment and hydrolysis (HTPH) were applied to examine whether differences exist in the composition and digestibility within a single pretreated wood chip due to heterogeneous pretreatment across its thickness. Heat transfer modeling, Simons’ stain testing, magnetic resonance imaging (MRI), and scanning electron microscopy (SEM) were applied to probe the effects of pretreatment within and between pretreated wood samples to shed light on potential causes of variation, pointing to enzyme accessibility (i.e., pore size) distribution being a key factor dictating enzyme digestibility in these samples. Application of these techniques demonstrated that the effectiveness of pretreatment of Populus tremuloides can vary substantially over the chip thickness at short pretreatment times, resulting in spatial digestibility effects and overall lower sugar yields in subsequent enzymatic hydrolysis. Conclusions These results indicate that rapid decompression pretreatments (e.g., steam explosion) that specifically alter accessibility at lower temperature conditions are well suited for larger wood chips due to the non-uniformity in temperature and digestibility profiles that can result from high temperature and short pretreatment times. Furthermore, this study also demonstrated that wood chips were hydrated primarily through the natural pore structure during pretreatment, suggesting that preserving the natural grain and transport systems in wood during storage and chipping processes could likely promote pretreatment efficacy and uniformity

Patterning Techniques in Coplanar Micro/Nano Capacitive Sensors

Rapid technological advancements have led to increased demands for sensors. Hence, high performance suitable for next-generation technology is required. As sensing technology has numerous applications, various materials and patterning methods are used for sensor fabrication. This affects the characteristics and performance of sensors, and research centered specifically on these patterns is necessary for high integration and high performance of these devices. In this paper, we review the patterning techniques used in recently reported sensors, specifically the most widely used capacitive sensors, and their impact on sensor performance. Moreover, we introduce a method for increasing sensor performance through three-dimensional (3D) structures

Architecture Exploration of a Backprojection Algorithm for Real-Time Video SAR

This paper explores novel architectures for fast backprojection based video synthetic aperture radar (BP-VISAR) with multiple GPUs. The video SAR frame rate is analyzed for non-overlapped and overlapped aperture modes. For the parallelization of the backprojection process, a processing data unit is defined as the phase history data or range profile data from partial synthetic-apertures divided from the full resolution target data. Considering whether full-aperture processing is performed and range compression or backprojection are parallelized on a GPU basis, we propose six distinct architectures, each having a single-stream pipeline with a single GPU. The performance of these architectures is evaluated in both non-overlapped and overlapped modes. The efficiency of the BP-VISAR architecture with sub-aperture processing in the overlapped mode is accelerated further by filling the processing gap from the idling GPU resources with multi-stream based backprojection on multiple GPUs. The frame rate of the proposed BP-VISAR architecture with sub-aperture processing is scalable with the number of GPU devices for large pixel resolution. It can generate 4096 × 4096 video SAR frames of 0.5 m cross-range resolution in 23.0 Hz on a single GPU and 73.5 Hz on quad GPUs

Identification of Fine Dust in Schools through Comprehensive Chemical Characterization

Abstract The chemical characteristics of particulate matters collected from 53 schools in 2019 through 2022 were closely investigated to determine the main sources of classroom PM2.5. On average, indoor PM2.5 measured during class hours distributed from 3.3 μg/m3 to 45.97 μg/m3, and it consisted of 45% of ions, 33% of carbons, 17% of metals and others. The average indoor-to-outdoor ratio (I/O) of PM2.5 was 0.73. Values for I/O ranged from 0.6 to 0.91 for inorganic elements; 0.3 to 0.8 for ions; 0.50 to 2.69 for elemental carbons (EC), and 0.52 to 8.50 for organic carbons (OC). The linear correlation of indoor EC with concentrations of K+ and NO3− indicates that the contribution of combustion-related sources to classroom PM2.5 is significant in roadside schools. The findings from this study should help establish construction guidelines for urban schools near high-traffic areas

Inactivation of p38 kinase delays the onset of senescence in rabbit articular chondrocytes

Replicative senescence limits cellular proliferation in vivo and in vitro. Recently, other groups and we reported that p38 kinase plays a key role on the onset of senescence. In this study, we demonstrated that replicative senescence can be delayed in rabbit chondrocytes in vitro by that p38 kinase inactivation. We found that the activity of p38 kinase is elevated in senescent chondrocytes as compared to pre-senescent counterparts. To examine the role of p38 kinase on the onset of senescence, we inactivated the kinase pharmacologically or genetically using either a chemical inhibitor, SB203580, or dominant negative mutant forms of MKK6 and p38 (MKK6A and p38dn, respectively). We show that the inactivation of p38 kinase leads to the stimulation of proliferation, the extension of life span, and a delay in the onset of senescence, thus implying that p38 kinase limits the life span of rabbit articular chondrocytes in vitro.The National Research Laboratory Program of the Korean Ministry of Science and Technology (to S.D.Y.) and Molecular Aging Research Center (to S.D.Y.) support this research

Impact of Pseudolignin versus Dilute Acid-Pretreated Lignin on Enzymatic Hydrolysis of Cellulose

To evaluate the inhibition effects of pseudolignin to enzymatic hydrolysis of cellulose in comparison to lignin, enzymatic mild acidolysis lignin (EMAL) was isolated from poplar after an 8 min pretreatment at 170 °C using 0.5% H₂SO₄. Fourier transform infrared (FT-IR) and ¹³C NMR characterization revealed that the poplar lignin was partially degraded during the pretreatment and did not contain detectable amounts of pseudolignin. Holocellulose was treated with varying amounts of pseudolignin and/or EMAL dissolved in <i>p</i>-dioxane and then dried. The treated and control holocellulose was then treated to a standard cellulase treatment, and the results from enzymatic hydrolysis of these samples showed that the dilute acid-pretreated lignin inhibited hydrolysis in the initial stage but had a negligible impact on the overall cellulose-to-glucose conversion yield. In contrast, pseudolignin significantly reduced the overall enzymatic conversion yield of cellulose to glucose. This study suggests that pseudolignin formation needs to be avoided because it is more detrimental to enzymatic hydrolysis of cellulose than dilute acid-pretreated lignin

Practical Electromagnetic Disturbance Analysis on Commercial Contactless Smartcards

Contactless smart cards are being widely employed in electronic passports, monetary payments, access control systems, and so forth, because of their advantages such as convenience and ease of maintenance. In this paper, we present a new side-channel attack method for contactless smart cards. This method exploits the information leakage stemming from electromagnetic disturbances (EMD). We also made a convenient and low-cost EMD reader board that performs side-channel attacks on contactless smart cards. In order to demonstrate that EMDs can become another information-leakage side channel, we have carried out side-channel analysis on a commercial contactless smart card that performs 128-bit ARIA encryptions, and we have been able to successfully find all 16 bytes of the ARIA key from the target device. From our experimental results, we conclude that the proposed EMD analysis yields better results than the conventional power analysis