Outcomes of a Course Design Workshop Series Implemented in a Team-Based and Diverse Classroom Setting

Studies provide extensive evidence that a diverse faculty and staff in academia helps bring a wide range of backgrounds, perspectives, experiences, and innovation.[1] In this regard, a 9- session course was taught in Summer 2019 titled Transforming Your Research Into Teaching, that provided 15 aspiring faculty with a platform to more deeply understand the significance of diversity and community in teaching and learning. In this course, the graduate students and postdoctoral fellows from widely divergent backgrounds at Iowa State University designed a new course related to their own research work/interest, in a team-based and diverse classroom-based setting. The teaching-as-research question addressed in this study was—How Effective Teambased Learning (TBL) and Classroom Diversity are in Preparing Future Teachers through a Course Design Workshop Series? Graduate students and postdocs at R1 universities mostly strive to do research, while many of them aspire to land faculty positions that require teaching and leadership capabilities. Unfortunately, they hardly get any teaching training, moreover in a diverse and TBL environment, making a course like this crucial to their success. Course impact was measured using 6-point Likert scales and analyzed descriptively. Data and participant feedback were indicative of significant learning in effective course design from a diverse and team-based setting, something that other aspirants can explore in planning academic careers or after landing faculty positions, that they can implement in their workplace to develop a richly diverse and dynamic intellectual community

A hybrid multifunctional physicochemical sensor suite for continuous monitoring of crop health

This work reports a first-of-its-kind hybrid wearable physicochemical sensor suite that we call PlantFit for simultaneous measurement of two key phytohormones, salicylic acid, and ethylene, along with vapor pressure deficit and radial growth of stem in live plants. The sensors are developed using a low-cost and roll-to-roll screen printing technology. A single integrated flexible patch that contains temperature, humidity, salicylic acid, and ethylene sensors, is installed on the leaves of live plants. The strain sensor with in-built pressure correction capability is wrapped around the plant stem to provide pressure-compensated stem diameter measurements. The sensors provide real-time information on plant health under different amounts of water stress conditions. The sensor suite is installed on bell pepper plants for 40 days and measurements of salicylic acid, ethylene, temperature, humidity, and stem diameter are recorded daily. In addition, sensors are installed on different parts of the same plant to investigate the spatiotemporal dynamics of water transport and phytohormone responses. Subsequent correlation and principal component analyses demonstrate the strong association between hormone levels, vapor pressure deficit, and water transport in the plant. Our findings suggest that the mass deployment of PlantFit in agricultural settings will aid growers in detecting water stress/deficiency early and in implementing early intervention measures to reduce stress-induced yield decline

IoT-Enabled Integrated Smart Wound Sensor for Multiplexed Monitoring of Inflammatory Biomarkers at the Wound Site

Chronic wounds that stall at the inflammatory phase of healing may create several life threatening complications such as tissue damage, septicemia, and organ failures. In order to prevent these adverse clinical outcomes and accelerate the wound healing process, it is crucial to monitor the wound status in real-time so that immediate therapeutic interventions can be implemented. In addition, continuous monitoring of the wound status can prevent drug overdose at the wound site, leading to on-demand and personalized drug delivery. Inflammatory mediators, such as Interleukin-6 (IL-6) and Interleukin-10 (IL-10) are promising indicators for the progression of wound healing and predictors of disease severity. Toward this end, this work reports a flexible wound patch for multiplexed monitoring of IL-6 and IL-10 at the wound site in order to provide real-time feedback on the inflammation phase of the wound. An optimized composition of gold nanoparticles integrated multiwalled carbon nanotube was demonstrated to improve sensor performance substantially. The sensor also exhibited excellent repeatable, reversible, and drift characteristics. A miniaturized Internet-of-things (IoT)-enabled potentiostat was also developed and integrated with the flexible sensor to realize a wearable system. This IoT-enabled wearable device provides a smart and cost-effective solution to improving the existing wound care through continuous, real-time, and in-situ monitoring of multiple wound biomarkers

Benefits of a Multi-institutional, Hybrid Approach to Teaching Course Design for Graduate Students, Postdoctoral Scholars, and Leaders

In this study, graduate students and postdoctoral scholars participated in a hybrid, multi-institutional workshop series about course design. Trainees developed college courses based on their research expertise, posting works-in-progress to a shared, online drive for peer review and collaboration. Learners also met weekly with local facilitators at their institution. The program led to similar learning outcomes as when the program was previously run in a face-to-face only format at one institution. However, the multi-institutional design led to additional benefits, especially for leaders at each institution, who described a rich learning community in their collaborative work

Nano-structure-based optical sensors fabrication and validation to gas sensing applications

We present three different nano-resonant structures (nanoposts, nanoholes etc.) fabricated on either bulk substrate or micron size tip of optical fiber and one graphene oxide coated glass substrate for gas detection in visible or mid-infrared region of electromagnetic spectrum. Nanostructures provide an efficient way to control and manipulate light at nanoscale paving the way for the development of reliable, sensitive, selective and miniaturized gas sensing technologies. Moreover, the inherent light guiding property of optical fiber over long distances, their microscopic cross-section, their efficient integration capabilities with gas absorption coatings and mechanical flexibility make them suitable for remote sensing applications. The three nanostructure-based gas sensing techniques are based on the detection of surface plasmon resonance (SPR) wavelength shifts, guided mode resonance (GMR) wavelength shifts, and Rayleigh anomaly (RA) mode intensity variations. The SPR and GMR based sensors operate in the visible region of light spectrum. Later, we also integrate a heater with the GMR-based fiber-tip sensor to realize a reusable gas sensor having tunable sensor recovery time. The RA-based sensor is realized by solvent-casting of chalcogenide glass to work as mid-infrared optical resonator. Further, we utilize the dynamic variations in infrared values of graphene oxide in response to gas to realize a gas sensor. First, we present a high-sensitivity gas sensor based on plasmonic crystal incorporating a thin layer of graphene oxide. The presented plasmonic crystal is formed by an array of polymeric nanoposts with gold disks at the top and perforated nanoholes in a gold thin film at the bottom. The thin coating of graphene oxide assembled on the top surface of mushroom plasmonic nanostructures works as the gas absorbent material for the sensor. The optical response of the plasmonic nanostructure is altered due to different concentrations of gas absorbed in the graphene oxide coating. By coating the surface of multiple identical plasmonic crystals with different thicknesses of graphene oxide layer, the effective refractive index of the graphene oxide layer on each plasmonic crystal will be differently modulated when responding to a specific gas. This allows identifying various gas species using the principal component analysis-based pattern recognition algorithm. The present plasmonic nanostructure offers a promising approach to detect various volatile organic compounds. Second, we report a simple yet efficient method of transferring nanopatterns to optical fiber tip. We have also demonstrated a TiO2 coated GMR structure which is sensitive to changes in surrounding refractive index and provides shifts in its resonant wavelength. The GMR sensor at the fiber tip is also demonstrated to work as a gas sensor by coating it with a thin layer of graphene oxide. This simplified and rapid nanostructuring at fiber tip can contribute to remote sensing applications through the insertion of the nanopatterned fiber tips into aqueous and gaseous analytes in regions otherwise inaccessible. Third, we present the first heater integrated nanostructured optical fiber of 200 à ¯à ¿à ½m diameter to realize a high-sensitivity and reusable fiber-optic gas sensor. In our GMR-enabled fiber-optic gas sensor, resonance shifts upon the adsorption of the analytes on the graphene oxide (GO) coated sensor surface. For repeated use of this sensor, a regeneration of the sensor surface is required by a complete desorption of the analyte molecules from the GO layer. In our presented design, this has been achieved by the integration of a controllable heater at the fiber tip. Fourth, we present a straightforward analysis based on the maximum and minimum envelopes of the reflection spectra to dynamically investigate the changes in complex refractive index of graphene oxide in response to gases. The performance of graphene oxide -based gas sensors is strongly influenced by the variations in optical properties of graphene oxide when exposed to gas. The presented method does not require any complex dispersion model as compared to ellipsometry. Accordingly, the technique we employ can be leveraged to reliably evaluate the optical performance of any graphene oxide-based gas sensors in a simpler manner, when compared to ellipsometry. Furthermore, the accuracy of the derived values of complex refractive index of the graphene oxide layer has been confirmed by comparing with literature. Finally, we report the development of a first of a kind planar resonant structure that enhances the mid-IR absorption by the analyte adsorbed on its surface, enabling highly sensitive and selective label-free detection of gas and/or biomarkers. Chalcogenide glasses (As2S3) are promising for infrared photonics owing to their transparency in visible to far infrared, where various biomolecules and gases have their characteristic absorption lines, arising from rotational-vibrational transitions. Here we present the proposed design of a nanoscale tunable planar mid-IR optical resonator, realized by solvent-casting of As2S3. Our technique of preparing nanostructure having resonance at mid-IR enables the realization of mid-IR bio as well as gas sensors.</p

Determination of dynamic variations in the optical properties of graphene oxide in response to gas exposure based on thin-film interference

We present an effective yet simple approach to study the dynamic variations in optical properties (such as the refractive index (RI)) of graphene oxide (GO) when exposed to gases in the visible spectral region, using the thin-film interference method. The dynamic variations in the complex refractive index of GO in response to exposure to a gas is an important factor affecting the performance of GO-based gas sensors. In contrast to the conventional ellipsometry, this method alleviates the need of selecting a dispersion model from among a list of model choices, which is limiting if an applicable model is not known a priori. In addition, the method used is computationally simpler, and does not need to employ any functional approximations. Further advantage over ellipsometry is that no bulky optics is required, and as a result it can be easily integrated into the sensing system, thereby allowing the reliable, simple, and dynamic evaluation of the optical performance of any GO-based gas sensor. In addition, the derived values of the dynamically changing RI values of the GO layer obtained from the method we have employed are corroborated by comparing with the values obtained from ellipsometry.This article is published as Tabassum, Shawana, Liang Dong, and Ratnesh Kumar. "Determination of dynamic variations in the optical properties of graphene oxide in response to gas exposure based on thin-film interference." Optics Express 26, no. 5 (2018): 6331-6344. DOI: 10.1364/OE.26.006331. Posted with permission.</p

Outcomes of a Course Design Workshop Series Implemented in a Team-Based and Diverse Classroom Setting

Studies provide extensive evidence that a diverse faculty and staff in academia helps bring a wide range of backgrounds, perspectives, experiences, and innovation.[1] In this regard, a 9- session course was taught in Summer 2019 titled Transforming Your Research Into Teaching, that provided 15 aspiring faculty with a platform to more deeply understand the significance of diversity and community in teaching and learning. In this course, the graduate students and postdoctoral fellows from widely divergent backgrounds at Iowa State University designed a new course related to their own research work/interest, in a team-based and diverse classroom-based setting. The teaching-as-research question addressed in this study was—How Effective Teambased Learning (TBL) and Classroom Diversity are in Preparing Future Teachers through a Course Design Workshop Series? Graduate students and postdocs at R1 universities mostly strive to do research, while many of them aspire to land faculty positions that require teaching and leadership capabilities. Unfortunately, they hardly get any teaching training, moreover in a diverse and TBL environment, making a course like this crucial to their success. Course impact was measured using 6-point Likert scales and analyzed descriptively. Data and participant feedback were indicative of significant learning in effective course design from a diverse and team-based setting, something that other aspirants can explore in planning academic careers or after landing faculty positions, that they can implement in their workplace to develop a richly diverse and dynamic intellectual community.</p

Optical Sensing Technologies to Elucidate the Interplay between Plant and Microbes

Plant-microbe interactions are critical for ecosystem functioning and driving rhizosphere processes. To fully understand the communication pathways between plants and rhizosphere microbes, it is crucial to measure the numerous processes that occur in the plant and the rhizosphere. The present review first provides an overview of how plants interact with their surrounding microbial communities, and in turn, are affected by them. Next, different optical biosensing technologies that elucidate the plant-microbe interactions and provide pathogenic detection are summarized. Currently, most of the biosensors used for detecting plant parameters or microbial communities in soil are centered around genetically encoded optical and electrochemical biosensors that are often not suitable for field applications. Such sensors require substantial effort and cost to develop and have their limitations. With a particular focus on the detection of root exudates and phytohormones under biotic and abiotic stress conditions, novel low-cost and in-situ biosensors must become available to plant scientists