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  1. Stimulated Raman projection tomography is a label-free volumetric chemical imaging technology allowing three-dimensional (3D) reconstruction of chemical distribution in a biological sample from the angle-dependent stimulated Raman scattering projection images. However, the projection image acquisition process requires rotating the sample contained in a capillary glass held by a complicated sample rotation stage, limiting the volumetric imaging speed, and inhibiting the study of living samples. Here, we report a tilt-angle stimulated Raman projection tomography (TSPRT) system which acquires angle-dependent projection images by utilizing tilt-angle beams to image the sample from different azimuth angles sequentially. The TSRPT system, which is free of sample rotation, enables rapid scanning of different views by a tailor-designed four-galvo-mirror scanning system. We present the design of the optical system, the theory, and calibration procedure for chemical tomographic reconstruction. 3D vibrational images of polystyrene beads and C. elegans are demonstrated in the C-H vibrational region.

  2. This paper is the culmination of four years of an NSF-funded project implementing and assessing an undergraduate additive manufacturing course at three large state universities: Texas Tech University, Kansas State University, and California State University – Northridge. The research questions addressed are: (1) What are the changes in skill and knowledge concerning additive manufacturing experienced by undergraduate students? (2) What is the effect of this course on attitudes towards engineering and self-efficacy in engineering for enrolled undergraduate students? The sample consists of four years of data from the undergraduate students enrolled in the course at all three universities (combined N = 196). Our method for data collection was matched-pair surveys that contained both (i) an assessment for content knowledge and (ii) an attitudinal assessment previously validated in published research for data collection about attitudes towards engineering. Matched-pair surveys means that we collected data from Student X at Time 1 (before being taught) and then again from at Time 2 (after being taught) and are able to directly compare any change in content knowledge or attitude within the same person. We also collected demographic information to be able to see whether changes in, for example, women differed from those in men.more »All undergraduates experienced statistically significant increases in content knowledge and additive manufacturing skills. In an intriguing finding, female students outperformed male students, which fits with the research that indicates that engineering courses which emphasize pragmatic and real-world applications, as well as those that use group work, will disproportionately help underserved engineering populations like women and people of color succeed. Fitting with the above finding, undergraduates noted that they perceived that they had increased in teamwork, communication, and computer programming skills. These gains were particularly high in female students and students of color.« less
    Free, publicly-accessible full text available August 1, 2023
  3. Free, publicly-accessible full text available April 8, 2023
  4. Panning, Eric M. ; Liddle, J. Alexander (Ed.)
    Free, publicly-accessible full text available May 25, 2023
  5. von Freymann, Georg ; Blasco, Eva ; Chanda, Debashis (Ed.)
    Free, publicly-accessible full text available March 5, 2023
  6. Free, publicly-accessible full text available March 16, 2023
  7. As one of the latest additions to the 2D nanomaterials family, black phosphorene (BP, monolayer or few-layer black phosphorus) has gained much attention in various forms of solar cells. This is due largely to its intriguing semiconducting properties such as tunable direct bandgap (from 0.3 eV in the bulk to 2.0 eV in the monolayer), extremely high ambipolar carrier mobility, broad visible to infrared light absorption, etc. These appealing optoelectronic attributes make BP a multifunctional nanomaterial for use in solar cells via tailoring carrier dynamics, band energy alignment, and light harvesting, thereby promoting the rapid development of third-generation solar cells. Notably, in sharp contrast to the copious work on revealing the fundamental properties of BP, investigation into the utility of BP is comparatively less, particularly in the area of photovoltaics. Herein, we first identify and summarize an array of unique characteristics of BP that underpin its application in photovoltaics, aiming at providing inspiration to develop new designs and device architectures of photovoltaics. Subsequently, state-of-the-art synthetic routes ( i.e. , top-down and bottom-up) to scalable BP production that facilitates its applications in optoelectronic materials and devices are outlined. Afterward, recent advances in a diverse set of BP-incorporated solar cells, where BPmore »may impart electron and/or hole extraction and transport, function as a light absorber, provide dielectric screening for enhancing exciton dissociation, and modify the morphology of photoabsorbers, are discussed, including organic solar cells, dye-sensitized solar cells, heterojunction solar cells and perovskite solar cells. Finally, the challenges and opportunities in this rapidly evolving field are presented.« less
  8. Helical structures exhibit novel optical and mechanical properties and are commonly used in different fields such as metamaterials and microfluidics. A few methods exist for fabricating helical microstructures, but none of them has the throughput or flexibility required for patterning a large surface area with tunable pitch. In this paper, we report a method for fabricating helical structures with adjustable forms over large areas based on multiphoton polymerization (MPP) using single-exposure, three dimensionally structured, self-accelerating, axially tunable light fields. The light fields are generated as a superposition of high-order Bessel modes and have a closed-form expression relating the design of the phase mask to the rotation rate of the beam. The method is used to fabricate helices with different pitches and handedness in the material SU-8. Compared to point-by-point scanning, the method reported here can be used to reduce fabrication time by two orders of magnitude, paving the way for adopting MPP in many industrial applications.