Jason Kronenfeld
Ph.D. Student in Chemistry, admitted Autumn 2021
Bio
Jason Kronenfeld holds a Bachelors of Science in Chemistry with minors in French and Math from The University of Arizona (Graduated May 2021, Summa Cum Laude with Honors). Jason spent his time at UArizona conducting research in Benjamin J. Renquist's group and working with Honors students as a Resident Assistant.
He joined the Renquist research group in 2017 where he has worked on projects related to lactation, metabolic rate, hyperinsulinemia and insulin resistance, asthma, and more. He led work on two projects. 1) Understanding the mechanism by which heat suppresses food intake as an effect of global warming. Increasing heat-stressed food intake is proposed to increase milk production in lactating mammals, increase animal efficiency, and decrease milk production costs. 2) Creating a novel approach to address glycemic control for treatment of type two diabetes mellitus – a collaboration with Dr. Khanna's research group to conduct in silico, in vivo, and in vitro testing of the novel approach.
In Fall 2021, Jason entered the Stanford University PhD program in chemistry, to be eventually followed with a post-doctoral fellowship with the ultimate goal of acting as a principal investigator in academia. He performs research in the DeSimone Lab focused on applications of high-resolution continuous liquid interface production (CLIP) under a National Science Foundation Graduate Research Fellowship. Outside of the lab, Jason is involved in research ethics and public communication initiatives as well as a student-led waltz performance group (Stanford Committee on Research, The Civilian, and the Viennese Ball Opening Committee, respectively).
Education & Certifications
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BS, The University of Arizona, Chemistry (2021)
All Publications
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Direct measurement of forces in air-based acoustic levitation systems.
The Review of scientific instruments
2024; 95 (9)
Abstract
Acoustic levitation is frequently used for non-contact manipulation of objects and to study the impact of microgravity on physical and biological processes. While the force field produced by sound pressure lifts particles against gravity (primary acoustic force), multiple levitating objects in the same acoustic cavity interact via forces that arise from scattered sound (secondary acoustic forces). Current experimental techniques for obtaining these force fields are not well-suited for mapping the primary force field at high spatial resolution and cannot directly measure the secondary scattering force. Here, we introduce a method that can measure both acoustic forces in situ, including secondary forces in the near-field limit between arbitrarily shaped, closely spaced objects. Operating similarly to an atomic force microscope, the method inserts into the acoustic cavity a suitably shaped probe tip at the end of a long, flexible cantilever and optically detects its deflection. This makes it possible to measure forces with a resolution better than 50 nN and also to apply stress or strain in a controlled manner to manipulate levitated objects. We demonstrate this by extracting the acoustic potential present in a levitation cavity, directly measuring the acoustic scattering force between two objects, and applying tension to a levitated granular raft of acoustically bound particles in order to obtain the force-displacement curve for its deformation.
View details for DOI 10.1063/5.0225745
View details for PubMedID 39230560
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Growing three-dimensional objects with light.
Proceedings of the National Academy of Sciences of the United States of America
2024; 121 (28): e2303648121
Abstract
Vat photopolymerization (VP) additive manufacturing enables fabrication of complex 3D objects by using light to selectively cure a liquid resin. Developed in the 1980s, this technique initially had few practical applications due to limitations in print speed and final part material properties. In the four decades since the inception of VP, the field has matured substantially due to simultaneous advances in light delivery, interface design, and materials chemistry. Today, VP materials are used in a variety of practical applications and are produced at industrial scale. In this perspective, we trace the developments that enabled this printing revolution by focusing on the enabling themes of light, interfaces, and materials. We focus on these fundamentals as they relate to continuous liquid interface production (CLIP), but provide context for the broader VP field. We identify the fundamental physics of the printing process and the key breakthroughs that have enabled faster and higher-resolution printing, as well as production of better materials. We show examples of how in situ print process monitoring methods such as optical coherence tomography can drastically improve our understanding of the print process. Finally, we highlight areas of recent development such as multimaterial printing and inorganic material printing that represent the next frontiers in VP methods.
View details for DOI 10.1073/pnas.2303648121
View details for PubMedID 38950359
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Roll-to-roll, high-resolution 3D printing of shape-specific particles.
Nature
2024; 627 (8003): 306-312
Abstract
Particle fabrication has attracted recent attention owing to its diverse applications in bioengineering1,2, drug and vaccine delivery3-5, microfluidics6,7, granular systems8,9, self-assembly5,10,11, microelectronics12,13 and abrasives14. Herein we introduce a scalable, high-resolution, 3D printing technique for the fabrication of shape-specific particles based on roll-to-roll continuous liquid interface production (r2rCLIP). We demonstrate r2rCLIP using single-digit, micron-resolution optics in combination with a continuous roll of film (in lieu of a static platform), enabling the rapidly permutable fabrication and harvesting of shape-specific particles from a variety of materials and withcomplex geometries, including geometries not possible to achieve with advanced mould-based techniques. We demonstrate r2rCLIP production of mouldable and non-mouldable shapes with voxel sizes as small as 2.0*2.0m2 in the print plane and 1.1±0.3m unsupported thickness, at speeds of up to 1,000,000particles per day. Such microscopic particles with permutable, intricate designs enable direct integration within biomedical, analytical and advanced materials applications.
View details for DOI 10.1038/s41586-024-07061-4
View details for PubMedID 38480965
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Single-digit-micrometer-resolution continuous liquid interface production.
Science advances
2022; 8 (46): eabq2846
Abstract
To date, a compromise between resolution and print speed has rendered most high-resolution additive manufacturing technologies unscalable with limited applications. By combining a reduction lens optics system for single-digit-micrometer resolution, an in-line camera system for contrast-based sharpness optimization, and continuous liquid interface production (CLIP) technology for high scalability, we introduce a single-digit-micrometer-resolution CLIP-based 3D printer that can create millimeter-scale 3D prints with single-digit-micrometer-resolution features in just a few minutes. A simulation model is developed in parallel to probe the fundamental governing principles in optics, chemical kinetics, and mass transport in the 3D printing process. A print strategy with tunable parameters informed by the simulation model is adopted to achieve both the optimal resolution and the maximum print speed. Together, the high-resolution 3D CLIP printer has opened the door to various applications including, but not limited to, biomedical, MEMS, and microelectronics.
View details for DOI 10.1126/sciadv.abq2846
View details for PubMedID 36383664
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A Leak-Free Head-Out Plethysmography System to Accurately Assess Lung Function in Mice.
Journal of applied physiology (Bethesda, Md. : 1985)
2022
Abstract
Mice are a valuable model for elegant studies of complex, systems-dependent diseases, including pulmonary diseases. Current tools to assess lung function in mice are either terminal or lack accuracy. We set out to develop a low-cost, accurate, head-out variable-pressure plethysmography system to allow for repeated, non-terminal measurements of lung function in mice. Current head-out plethysmography systems are limited by air leaks that prevent accurate measures of volume and flow. We designed an inflatable cuff that encompasses the mouse's neck preventing air leak. We wrote corresponding software to collect and analyze the data, remove movement artifacts, and automatically calibrate each dataset. This software calculates inspiratory/expiratory volume, inspiratory/expiratory time, breaths per minute, mid-expiratory flow, and end-inspiratory pause. To validate the use, we established that our plethysmography system accurately measured tidal breathing, the bronchoconstrictive response to methacholine, sex and age associated changes in breathing, and breathing changes associated with house dust mite sensitization. Our estimates of volume, flow, and timing of breaths are in line with published estimates, we observed dose-dependent decreases in volume and flow in response to methacholine (P < 0.05), increased lung volume and decreased breathing rate with aging (P < 0.05), and that house dust mite sensitization decreased volume and flow (P <0.05) while exacerbating the methacholine induced increases in inspiratory and expiratory time (P < 0.05). We describe an accurate, sensitive, low-cost, head-out plethysmography system that allows for longitudinal studies of pulmonary disease in mice.
View details for DOI 10.1152/japplphysiol.00835.2021
View details for PubMedID 35608203
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A critical role of hepatic GABA in the metabolic dysfunction and hyperphagia of obesity
CELL REPORTS
2021; 35 (13): 109301
Abstract
Hepatic lipid accumulation is a hallmark of type II diabetes (T2D) associated with hyperinsulinemia, insulin resistance, and hyperphagia. Hepatic synthesis of GABA, catalyzed by GABA-transaminase (GABA-T), is upregulated in obese mice. To assess the role of hepatic GABA production in obesity-induced metabolic and energy dysregulation, we treated mice with two pharmacologic GABA-T inhibitors and knocked down hepatic GABA-T expression using an antisense oligonucleotide. Hepatic GABA-T inhibition and knockdown decreased basal hyperinsulinemia and hyperglycemia and improved glucose intolerance. GABA-T knockdown improved insulin sensitivity assessed by hyperinsulinemic-euglycemic clamps in obese mice. Hepatic GABA-T knockdown also decreased food intake and induced weight loss without altering energy expenditure in obese mice. Data from people with obesity support the notion that hepatic GABA production and transport are associated with serum insulin, homeostatic model assessment for insulin resistance (HOMA-IR), T2D, and BMI. These results support a key role for hepatocyte GABA production in the dysfunctional glucoregulation and feeding behavior associated with obesity.
View details for DOI 10.1016/j.celrep.2021.109301
View details for Web of Science ID 000668072600010
View details for PubMedID 34192532
- Development of a GABA Transaminase Inhibitor That Does Not Penetrate the Blood-Brain Barrier The University of Arizona Honors College. Thesis Repository. 2021
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Feed intake-dependent and -independent effects of heat stress on lactation and mammary gland development
JOURNAL OF DAIRY SCIENCE
2020; 103 (12): 12003-12014
Abstract
With a growing population, a reliable food supply is increasingly important. Heat stress reduces livestock meat and milk production. Genetic selection of high-producing animals increases endogenous heat production, while climate change increases exogenous heat exposure. Both sources of heat exacerbate the risk of heat-induced depression of production. Rodents are valuable models to understand mechanisms conserved across species. Heat exposure suppresses feed intake across homeothermic species including rodents and production animal species. We assessed the response to early-mid lactation or late-gestation heat exposure on milk production and mammary gland development/function, respectively. Using pair-fed controls we experimentally isolated the feed intake-dependent and -independent effects of heat stress on mammary function and mass. Heat exposure (35°C, relative humidity 50%) decreased daily feed intake. When heat exposure occurred during lactation, hypophagia accounted for approximately 50% of the heat stress-induced hypogalactia. Heat exposure during middle to late gestation suppressed feed intake, which was fully responsible for the lowered mammary gland weight of dams at parturition. However, the impaired mammary gland function in heat-exposed dams measured by metabolic rate and lactogenesis could not be explained by depressed feed consumption. In conclusion, mice recapitulate the depressed milk production and mammary gland development observed in dairy species while providing insight regarding the role of feed intake. This opens the potential to apply genetic, experimental, and pharmacological models unique to mice to identify the mechanism by which heat is limiting animal production.
View details for DOI 10.3168/jds.2020-18675
View details for Web of Science ID 000603029300036
View details for PubMedID 33041042
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Determining the Role of Obesity and Muscarinic Signaling in Asthma
WILEY. 2020
View details for DOI 10.1096/fasebj.2020.34.s1.05674
View details for Web of Science ID 000546107901356
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It's Strong, It's Stable, It's Streptavidin
FEDERATION AMER SOC EXP BIOL. 2015
View details for Web of Science ID 000361470500058