A Film Fabrication Process on Transparent Substrate using Mask Projection Micro-Stereolithography

In this study, a Mask Projection Micro-Stereolithography (MPµSLA) process with the ability to cure a film of various thicknesses on transparent substrates is presented. Incident radiation, patterned by a dynamic mask, passes through a transparent substrate to cure photopolymer resin layers that grow progressively from the substrate surface. When compared to existing Stereolithography techniques, this technique eliminates the necessity of recoating, reducing process time and improving accuracy. A film of varying thicknesses can be fabricated on flat or curved transparent substrates. Models of the optical system and resin cure are developed and reported. An existing MPµSLA process planning method is being extended to account for radiation transmission through a substrate. The models are verified using experiments.Mechanical Engineerin

In-class vs. online administration of concept inventories and attitudinal assessments

This study investigates differences in student responses to in-class and online administrations of the Force Concept Inventory (FCI), Conceptual Survey of Electricity and Magnetism (CSEM), and the Colorado Learning Attitudes about Science Survey (CLASS). Close to 700 physics students from 12 sections of three different courses were instructed to complete the concept inventory relevant to their course, either the FCI or CSEM, and the CLASS. Each student was randomly assigned to take one of the surveys in class and the other survey online using the LA Supported Student Outcomes (LASSO) system hosted by the Learning Assistant Alliance (LAA). We examine how testing environments and instructor practices affect participation rates and identify best practices for future use.Comment: 4 pages, 3 tables, 3 figures, Physics Education Research Conference proceeding

Acute Myelomonocytic Leukemia With Tetrasomy 8: Histologic and Immunophenotypic Features Mimicking Acute Promyelocytic Leukemia

Rare cases of acute myeloid leukemia (AML) with tetrasomy 8 have been reported. Tetrasomy 8, a poor prognostic factor, has been predominantly associated with AML with monocytic differentiation. We report an unusual case of acute myelomonocytic leukemia (AMML) with tetrasomy 8 showing histologic and immunophenotypic features mimicking acute promyelocytic leukemia (APL). The patient is a 63-year-old African American man with molar pain, gum swelling and bleeding, generalized fatigue, leukocytosis, anemia, and thrombocytopenia. A peripheral blood smear showed increased white cells with many immature granulocytic forms. Approximately 40% of the cells exhibited classical blast morphology, 40% were slightly enlarged and exhibited a small to moderate amount of cytoplasm with a variable number of cytoplasmic granules resembling atypical promyelocytes, and 10% exhibited morphology typical of promyelocytes. The presence of promyelocytes and atypical promyelocytes was highly suggestive of APL. Flow cytometry performed on the peripheral blood showed the leukemic cells to express CD11b (subset), CD33, CD56, and CD64 (subset), with no expression of HLA-DR or CD34, suggestive of APL; however, the blasts were negative for CD117. Subsequent bone marrow aspirate/biopsy evaluation was consistent with AMML. FISH analysis showed tetrasomy 8 and absence of PML/RARA gene rearrangement. In this case, AMML with tetrasomy 8 morphologically and immunophenotypically mimicked APL. The treatment and prognosis of these subtypes of AML are significantly different. This case illustrates the importance of cytogenetic analysis and thorough bone marrow evaluation in determining accurate diagnosis of AML

Electrical Control of Linear Dichroism in Black Phosphorus from the Visible to Mid-Infrared

The incorporation of electrically tunable materials into photonic structures such as waveguides and metasurfaces enables dynamic control of light propagation by an applied potential. While many materials have been shown to exhibit electrically tunable permittivity and dispersion, including transparent conducting oxides (TCOs) and III-V semiconductors and quantum wells, these materials are all optically isotropic in the propagation plane. In this work, we report the first known example of electrically tunable linear dichroism, observed here in few-layer black phosphorus (BP), which is a promising candidate for multi-functional, broadband, tunable photonic elements. We measure active modulation of the linear dichroism from the mid-infrared to visible frequency range, which is driven by anisotropic quantum-confined Stark and Burstein-Moss effects, and field-induced forbidden-to-allowed optical transitions. Moreover, we observe high BP absorption modulation strengths, approaching unity for certain thicknesses and photon energies

Real-Time Interferometric Monitoring System for Exposure Controlled Projection Lithography

Stereolithography is an additive manufacturing process in which liquid photopolymer resin is cross-linked and converted to solid polymer with an ultraviolet light source. Exposure Controlled Projection Lithography (ECPL) is a stereolithographic process in which incident radiation, patterned by a dynamic mask, passes through a transparent substrate to cure a photopolymer layer that grows progressively from the substrate surface. In contrast to existing stereolithography techniques, this technique uses a gray-scale projected image, or alternatively a series of binary bit-map images, to produce a three-dimensional polymer object with the desired shape, and it can be used on either flat or curved substrates. Like most stereolithographic technologies, ECPL works in a unidirectional fashion. Calibration constants derived experimentally are fed to the software used to control the system. This unidirectional fabrication method does not, by itself, allow the system to compensate for minor variations, thereby limiting the overall accuracy of the process. We present here a simple, real-time monitoring system based on interferometry, which can be used to provide feedback control to the ECPL process, thus making it more robust and increasing system accuracy. The results obtained from this monitoring system provide a means to better visualize and understand the various phenomena occurring during the photopolymerization of transparent photopolymers.Mechanical Engineerin

Real-Time Selective Monitoring of Exposure Controlled Projection Lithography

Exposure Controlled Projection Lithography (ECPL) is a stereolithographic process in which incident radiation, patterned by a dynamic mask, passes through a transparent substrate to cure photopolymer which grows progressively from the substrate surface. We present here a novel method of capturing useful information about the curing process from a simple, inexpensive, real-time monitoring system based on interferometry. This approach can be used to provide feedback control to the ECPL process, thus making the process more robust and increasing system accuracy. The results obtained from this monitoring system provide a means to better visualize and understand the various phenomena occurring during the photopolymerization of transparent photopolymers. In order to lessen the measurement error, caused by internal diffraction within the substrate, the interferometry system has been designed such that the laser light used can be selectively targeted. This selective monitoring approach is experimentally validated to measure the height and profile of the cured part in real-time.Mechanical Engineerin

Growth of carbon nanotubes on quasicrystalline alloys

We report on the synthesis of carbon nanotubes on quasicrystalline alloys. Aligned multiwalled carbon nanotubes (MWNTs) on the conducting faces of decagonal quasicrystals were synthesized using floating catalyst chemical vapor deposition. The alignment of the nanotubes was found perpendicular to the decagonal faces of the quasicrystals. A comparison between the growth and tube quality has also been made between tubes grown on various quasicrystalline and SiO2 substrates. While a significant MWNT growth was observed on decagonal quasicrystalline substrate, there was no significant growth observed on icosahedral quasicrystalline substrate. Raman spectroscopy and high resolution transmission electron microscopy (HRTEM) results show high crystalline nature of the nanotubes. Presence of continuous iron filled core in the nanotubes grown on these substrates was also observed, which is typically not seen in MWNTs grown using similar process on silicon and/or silicon dioxide substrates. The study has important implications for understanding the growth mechanism of MWNTs on conducting substrates which have potential applications as heat sinks

Reimagining decent work through engaged scholarship: dynamics and boundaries of inclusive relationality

‘Decent Work’ is part of a United Nations’ Sustainable Development Goal and psychological construct associated with ‘good’ employment conditions (e.g. stability, security, fair pay, social protection, equality of opportunity and treatment for all). Despite a 30-year history, minority ethnic students and graduates remain some of the most excluded from employment. This session draws from a major study in Vietnam which positions Appreciative Inquiry as a form of engaged scholarship where minority ethnic groups collaborated with influential policy-makers, employers, and university seniors, to re-vision Decent Work and the pathways towards it. The session provides an experiential experiment which invites participants to imagine the application of the approach in their own context and reflect on the implications of the extant power structures and differentials in their own sociocultural settings. The frameworks and strategies for inclusion that emerged in Vietnam are shared as prompts to inspire dialogue around inclusive relationalities in engaged scholarship