Scholarworks
ScholarWorks is an open access repository for the capture of the intellectual work of Montana State University (MSU) in support of its teaching, research and service missions. MSU ScholarWorks is a central point of discovery for accessing, collecting, sharing, preserving, and distributing knowledge to the Montana State University community and the world.

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Recent Submissions
A Photovoltaic Self-Powered Volatile Organic Compounds Sensor Based on Asymmetric Geometry 2D MoS2 Diodes
(The Electrochemical Society, 2024-09) Fawzy, Mirette; Reza Mohammadzadeh, Mohammad; Abnavi, Amin; De Silva, Thushani; Ahmadi, Ribwar; Ghanbari, Hamidreza; Kabir, Fahmid; Kavanagh, Karen L.; Hasani, Amirhossein; Adachi, Michael M.
Transition metal dichalcogenides have gained considerable interest for vapour sensing applications due to their large surface-to-volume ratio and high sensitivity. Herein, we demonstrate a new self-powered volatile organic compounds (VOC) sensor based on asymmetric geometry multi-layer molybdenum disulfide (MoS2) diode. The asymmetric contact geometry of the MoS2 diode induces an internal built-in electric field resulting in self-powering via a photovoltaic response. While illuminated by UV-light, the sensor exhibited a high responsivity of ∼60% with a relatively fast response time of ∼10 sec to 200 ppm of acetone, without an external bias voltage. The MoS2 VOC diode sensor is a promising candidate for self-powered, fast, portable, and highly sensitive VOC sensor applications.
2D MoSe2 Geometrically Asymmetric Schottky Photodiodes
(Wiley, 2024-09) Ghanbari, Hamidreza; Abnavi, Amin; Ahmadi, Ribwar; Reza Mohammadzadeh, Mohammad; Fawzy, Mirette; Hasani, Amirhossein; Adachi, Michael M.
Optoelectronic devices based on geometrically asymmetric architecture have recently attracted attention due to their high performance as photodetectors and simple fabrication process. Herein, a p-type 2D MoSe2 photodetector based on geometrically asymmetric contacts is reported for the first time. The device exhibits a high current rectification ratio of ≈104 and a large self-powered photovoltage responsivity of ≈4.38 × 107 V W−1, as well as a maximum photocurrent responsivity of ≈430 mA W−1 along with a response time of ≈2.3 ms under 470 nm wavelength at 3 V bias voltage. The photocurrent responsivity is further enhanced to an ultrahigh responsivity of ≈1615 mA W−1 by applying a gate bias voltage due to the electrostatic modulation of carrier concentration in the MoSe2 channel. The simple fabrication process of the geometrically asymmetric MoSe2 diodes along with their high photodetection and diode rectifying performance make them excellent candidates for electronic and optoelectronic applications.
Elucidation of mechanisms of host plant resistance to wheat stem sawfly (Cephus cinctus Norton) in relation to antibiosis and the early stem solidness phenotype
(Montana State University - Bozeman, College of Agriculture, 2023) Hager, Megan Sunshine; Chairperson, Graduate Committee: David K. Weaver; This is a manuscript style paper that includes co-authored chapters.
In the North American Great Plains, wheat stem sawfly (WSS), Cephus cinctus Norton is a serious pest of cultivated cereals including common bread wheat (Triticum aestivum L.) and durum wheat (Triticum turgidum L. var durum). The solid stem phenotype is usually the basis of an effective management strategy in preventing infestation and yield loss in areas which experience pressure from large and damaging WSS populations. However solid stem expression can be negatively influenced by environmental effects and fully solid stems decrease the effectiveness of biological control of WSS by endemic parasitoids, highlighting a need for new sources of resistance outside of the solid stem phenotype. Here, we use 'omics technologies to comprehensively examine potential mechanisms of resistance including antibiotic resistance in oat, as well as small molecules, transcripts, photosynthetic parameters and volatile organic compounds in spring and durum wheat which help to explain decreased levels of infestation and lower incidence of stem cutting observed with the early solid stem phenotype. Genes and metabolites related to cellular organization, lignin composition and stem tissue structure appear to be involved in the resistance observed in oat and are also related to the early stem solidness phenotype in spring and durum wheat. Additionally, metabolic differences in abundance of lipids and carbohydrates were observed between oat and wheat as well as in spring and durum wheat near isogenic lines. Collectively, this research provides insight into the impacts that plant metabolites and gene expression may have on plant resistance to WSS.
Energy metabolism and mechanotransduction in osteoarthritic chondrocytes: targeted metabolic profiling and flux analysis
(Montana State University - Bozeman, College of Engineering, 2023) Erdogan, Ayten Ebru; Chairperson, Graduate Committee: Ronald K. June II; This is a manuscript style paper that includes co-authored chapters.
Osteoarthritis (OA) is a prevalent and debilitating disease that affects hundreds of millions people worldwide. One of OAs major consequences is the degradation of articular cartilage, leading to joint pain, stiffness, and loss of function. Currently, there is no treatment for OA. The existing interventions are mostly for suppressing the symptoms: physical therapy, anti-inflammatories, and pain management. The last resort is total joint replacement, which has long-term consequences especially for early-onset OA patients. Thus, researchers are focusing on understanding this complex disease and its molecular components to develop better treatments. Chondrocytes, the sole cell type in articular cartilage, play a crucial role in maintaining tissue homeostasis and responding to mechanical stimuli via synthesis of key structural components like collagen. However, the intracellular pathways underlying chondrocyte mechanotransduction are not fully understood, especially those related to central carbon metabolism. This thesis uses 13C isotopic labeling to trace carbon sources and downstream metabolites related to energy metabolism in vitro. Primary human articular chondrocytes from OA patients exposed to labeled glucose and glutamine, and their global and targeted metabolite profiles are assessed. The results show how both glucose and glutamine utilization as carbon sources flows through the TCA cycle. This work also develops a comprehensive model of mammalian carbon metabolism in OA primary human chondrocytes. The model integrates energy metabolism, amino acid synthesis, and transport reactions contributing to Collagen-II and Collagen-VI production. Using flux balance analysis (FBA), trade-offs between Collagen-II and Collagen-VI synthesis are evaluated based on ATP and carbon source requirements under different oxidative stress conditions. Then, these model predictions are presented with experimental data obtained from OA chondrocytes subjected to shear and compressive mechanical stimulation, which can be integrated in the model later on. These data shed new light on metabolism of primary OA chondrocytes and provides insight into potential therapeutic targets for OA intervention.
Interferometric methods for spatial-spectral holographic signal processing applications
(Montana State University - Bozeman, College of Letters & Science, 2023) Wolfe, Owen Robert; Chairperson, Graduate Committee: Wm. Randall Babbitt; This is a manuscript style paper that includes co-authored chapters.
Spatial spectral holographic (SSH) systems have applications in signal processing including spectrum analysis to optical correlation. Beam splitters and material interactions can affect the phase relationships between fields in separate spots in the material (or fields bypassing the material). Interferometric methods allow for these phase shifts to be exploited for two primary uses: the isolation of fields generated by the material and the amplification of signals and the amplification of signals in the chirped readout of programmed spectra. Stimulated photon echoes are used as the basis of SSH material-based optical systems and have been suggested as a protocol for optical quantum memory. These applications require the stimulated echo field to be isolated from a probe field. Current methods take an angular approach to isolating fields. An alternative approach uses interferometric methods to isolate fields in a way that can be implemented in a photonic integrated circuit. This dissertation will present a mathematical model for the isolation of stimulated photon echoes in both a 2-port Mach-Zehnder interferometer and a 4-port interferometer designed to emulate the isolation achieved via the angular "Box-Geometry" using interferometric methods. Experimental stimulated photon echo studies in a Mach-Zehnder interferometer built around a sample of 0.01% Tm 3+ : LiNbO 3 will demonstrate the principle of interferometric isolation of stimulated photon echoes. Maxwell-Bloch simulations will be used to demonstrate the principle of echo isolation in the 4-port interferometer. Use of the chirped interferometric readout of programmed spectra is demonstrated for SSH grating processing and spectrum analysis is shown in experiments in a sample of 0.01% Tm 3+ : LiNbO 3. Improvements to signal-to-noise ratio over traditional readout are seen by using a strong local oscillator in both applications. In spectrum analysis applications, the recovery of the proper spectral line shape is demonstrated, and SNR improvements are shown for a given read power. In the grating experiments, a non-linear noise floor was shown that created a constraint on the usable read power for these experiments. In this case, the interferometric readout was able to produce an improvement in the signal-to-noise ratio that could not be achieved using a stronger read power.