787 research outputs found
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A Film Fabrication Process on Transparent Substrate using Mask Projection Micro-Stereolithography
In this study, a Mask Projection Micro-Stereolithography (MP”SLA) 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 MP”SLA 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
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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
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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
âDecent Workâ is part of a United Nationsâ Sustainable Development Goal and psychological construct associated with âgoodâ 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
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