Upcoming Talks

 

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Archive of Previous Talks

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Upcoming Talks

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Tuesday 18 March 2025

University of Houston, Department of Chemistry, Houston, TX

Mimicking Nature: Controlling Charge, Heat, and Spin at Interfaces

Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry, Bioengineering, and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA

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Sunday 23 March 2025, 7¹⁰ AM, Online

American Chemical Society National Meeting, Global Virtual (PHYS) Symposium: Nanointerface Chemistry, 23 – 27 March 2025

Mimicking Nature: Controlling Charge, Heat, and Spin at Interfaces

Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry, Bioengineering, and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA

One of the key advances in nanoscience and nanotechnology has been our increasing ability to reach the limits of atomically precise structures. By having developed the “eyes” to see, to record spectra, and to measure function at the nanoscale, we have been able to fabricate structures with precision as well as to understand the important and intrinsic heterogeneity of function found in these assemblies. The physical, electronic, mechanical, thermal, and chemical connections that materials make to one another and to the outside world are critical. Just as the properties and applications of conventional semiconductor devices depend on these contacts, so do nanomaterials, many nanoscale measurements, and devices of the future. We explore the important roles that these contacts can play in preserving key transport and other properties. Initial nanoscale connections and measurements guide the path to future opportunities and challenges ahead. Band alignment, minimally disruptive connections, and control of spin and heat are all targets and can be characterized in both experiment and theory. I discuss our initial forays into this area in a number of materials systems.

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Sunday 23 March 2025, 8 AM, Online

American Chemical Society National Meeting, Global Virtual (PHYS) Symposium: Nanointerface Chemistry, 23 – 27 March 2025

Chirality and Spin: A New Twist in Hybrid Devices and Molecular Systems

Tianhan Liu, Yuwaraj Adhikari, Hailong Wang, Yiyang Jiang, Zhenqi Hua, Haoyang Liu, Yang Cheng, Kang L. Wang, Pedro Schlottmann, Hanwei Gao, Binghai Yan,
Jianhua Zhao, Peng Xiong, and Paul S. Weiss
1. Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA,
United States.
2. Physics, Florida State University, Tallahassee, FL, United States.
3. Institute of Semiconductors, Chinese Academy of Sciences, Beijing, Beijing, China.
4. Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel.
5. Electrical and Computer Engineering, University of California Los Angeles, Los Angeles, CA, United States

Chirality, or handedness, is a fundamental property in nature and a central topic in modern science. The relation between chirality and magnetism has been studied for over a century. More recently, the effect of chirality-induced spin selectivity (CISS) has been discovered in chiral organic molecules, where structural chirality can lead to different conductivities for electrons with opposite spins. This intriguing effect has significant implications on biorecognition processes, enantiomeric separations, and molecular memories and devices.

We focus on spin-dependent electron transport in chiral molecular junctions both at the atomic scale and in hybrid devices, to explore the interactions between structural chirality, electronic spins, and orbitals through CISS. Specifically, we study the spin-valve effect and Hanle effect and investigate the potential for novel approaches to spintronic devices free of any magnetic component.

Beyond electron transport studies, we investigate the fundamental mechanisms of chiral recognition and separations. Traditionally, the recognition and separation of enantiomers have focused on their spatial interactions with pure enantiomers. Recently, it has been suggested that exchange interactions between chiral molecules and a magnetic substrate could affect enantiomeric separations. Such investigations potentially provide guidance for spin-dependent chemical reactions and chiral catalysis.

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Sunday 23 March 2025, 11³⁰ AM, San Diego Convention Center, Ballroom 20D

American Chemical Society National Meeting, San Diego, CA, 23 – 27 March 2025, Special Symposium on Unlocking a New Era: How AI is Transforming Drug Discovery and Development

Cheminformatic Approach to Predictive Modelling Cosmeceutical Formulations Based on Skin Microbiome Chemical Interactions

Yae-won Michelle Jung, Jennifer Uyanga, AJ Addae, and Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry, Bioengineering, and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA

Topical skincare products and cosmeceuticals interact with the skin microbiome, popularly termed the “second skin.” The composition of an individual’s skin microbiome depends on various factors, such as age, gender, skin tone, and can also vary across different regions of the body. Additionally, environmental stressors such as frequency of sun exposure, humidity, and pollution can influence an individual’s skin microbiome. Previous studies have linked the skin’s microbiome diversity and commensal and pathogenic bacteria composition to the onset and presence of chronic skin conditions such as psoriasis and atopic dermatitis. Despite this phenomenon, profiling the behavior of the skin microbiome in response to cosmeceutical treatments is challenging. To address this, we propose that profiling the chemical behavior of the skin microbiome in response to widely used cosmeceutical treatments can enhance the predictions of efficacy, biofilm interactions, and tolerability challenges faced by modern cosmeceuticals.

Utilizing a cheminformatic framework, we link the efficacy of commonly utilized cosmeceutical materials (Vitamin C, retinol, niacinamide, and alpha-hydroxy acids) and their interactions with the skin microbiome through cosmeceutical-induced pH changes of bacterial biofilms, bacterial diversity, and other biological markers after topical application of products. By systematically cataloging the chemical properties of the microbiome under a range of application conditions noted in previous literature, we can predict improvements in epidermal health through known interactions of cosmeceutical materials with skin microbiome viability. This proposed cheminformatic framework can predictively enhance formulation design and the development of cosmeceutical treatments to interact favorably with the skin microbiome.

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Sunday 23 March 2025, 2¹⁰ PM, San Diego Convention Center, Room 31C

American Chemical Society National Meeting, San Diego, CA, Steve Stranick Memorial (ANYL) Symposium, 23 – 27 March 2025

Nanoscale Chemical Imaging – The Legacy of Dr. Stephan Stranick

Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry, Bioengineering, and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA

As a PhD student and as part of his extraordinary thesis work, Dr. Stephan Stranick invented and developed atomic-scale spectroscopic imaging methods to expand the systems that could be studied with scanning probe microscopies and spectroscopies. His work continued in his independent career as well as in our laboratory. We are now able to measure structure, function, and spectra simultaneously. I discuss examples at the ultimate limits of miniaturization of switches and motors based in multiple ways on Stranick’s early work in both microscopy and self-assembly, in biomolecular assemblies, and in measuring exposed and buried interactions and motion, all with extraordinary precision. By combining these spectroscopic imaging methods with ideas and methods from sparsity, we have been able to acquire statistically significant distributions of data that enable us to resolve and to understand heterogeneous structure, function, and mechanisms of molecules, materials, and assemblies at the nanoscale. The heterogeneity that we observe is a key feature that is present even for atomically precise structures. Stephan Stranick’s legacy is that the advances that he launched and led are opening the nanoscale world for understanding and control.

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Sunday 23 March 2025, 3 PM, San Diego Convention Center, Hall B2/C

American Chemical Society National Meeting, San Diego, CA, 23 – 27 March 2025, Nanoscience: Applications of Nanomaterials (INOR) Poster Session

Chemically Etched MXene Quantum Dots: A Scalable Approach for Enhanced Near-Infrared Emission

Judy Cheng, Haiyue Huang, Maximillian Floridia, Gilad Gani, Stefano Ippolito, Yury Gogotsi, and Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry, Bioengineering, and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA

Quantum dots have garnered significant attention for bioimaging and other applications due to their unique optical properties. However, traditional semiconductor quantum dots often contain toxic metallic elements, posing significant concerns regarding their biocompatibility and environmental impact. MXenes, a novel class of 2D layered materials, can be functionalized with surface groups and prepared with biocompatible transition metals such as titanium. In this work, we report a one-step chemical etching method to convert 2D MXene sheets into 0D MXene quantum dots (MQDs). The sizes of the as-prepared MQDs are in the range of 10-50 nm. Photoluminescence spectra show they have strong near-infrared emission with wavelengths exceeding 700 nm. In addition, we explore surface functionalization to optimize their physicochemical and optical properties. Our approach provides a scalable and efficient method to synthesizing biocompatible quantum dots for biomedical applications.

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Monday 24 March 2025, 8¹⁰ AM, Marriot Grand Ballroom, Section 6

American Chemical Society National Meeting, San Diego, CA, 23 – 27 March 2025

Science and Technology Developments for Global Food Security

Erika López Lara, Keith Peterman, Gregory P. Foy, and Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry, Bioengineering, and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA

Among the diverse effects of climate change on humanity, food insecurity stands out as one of the most critical aspects to solve. Rising temperatures and changing climate patterns threaten crop yields and livestock. Academia, government, and the private sector must work together on finding and promoting science- and technology-based solutions. Current strategies include climate-resilient crops, which are genetically modified to resist drought, pests, and diseases. In addition, precision monitoring technologies are being employed to optimize resources such as water and fertilizers. Agroecological practices play crucial roles by promoting biodiversity and capturing carbon. Among these innovations, alternative proteins, particularly those derived from plants sources and cellular agriculture, stand out as promising solutions for producing low-emission, nutritious food. These alternatives offer significant environmental benefits, including reduced water, land, and resource use. Compared to traditional livestock farming, they can be produced with 90% fewer resources, making them compelling options for addressing both food security and climate impact concerns, which are key topics that were discussed at COP29 in Baku, Azerbaijan. Food, water, and agriculture were discussed deeply including a climate initiative that will help build momentum for stakeholders to commit to collective action on agriculture issues. Science and technologies that promote resilient food systems as considered in COP29 will be discussed. 

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Monday 24 March 2025, 12 PM, San Diego Convention Center, Hall B2/C

American Chemical Society National Meeting, San Diego, CA, 23 – 27 March 2025

Cheminformatic Approach to Predictive Modelling Cosmeceutical Formulations Based on Skin Microbiome Chemical Interactions

Yae-won Michelle Jung, Jennifer Uyanga, AJ Addae, and Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry, Bioengineering, and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA

Topical skincare products and cosmeceuticals interact with the skin microbiome, popularly termed the “second skin.” The composition of an individual’s skin microbiome depends on various factors, such as age, gender, skin tone, and can also vary across different regions of the body. Additionally, environmental stressors such as frequency of sun exposure, humidity, and pollution can influence an individual’s skin microbiome. Previous studies have linked the skin’s microbiome diversity and commensal and pathogenic bacteria composition to the onset and presence of chronic skin conditions such as psoriasis and atopic dermatitis. Despite this phenomenon, profiling the behavior of the skin microbiome in response to cosmeceutical treatments is challenging. To address this, we propose that profiling the chemical behavior of the skin microbiome in response to widely used cosmeceutical treatments can enhance the predictions of efficacy, biofilm interactions, and tolerability challenges faced by modern cosmeceuticals.

Utilizing a cheminformatic framework, we link the efficacy of commonly utilized cosmeceutical materials (Vitamin C, retinol, niacinamide, and alpha-hydroxy acids) and their interactions with the skin microbiome through cosmeceutical-induced pH changes of bacterial biofilms, bacterial diversity, and other biological markers after topical application of products. By systematically cataloging the chemical properties of the microbiome under a range of application conditions noted in previous literature, we can predict improvements in epidermal health through known interactions of cosmeceutical materials with skin microbiome viability. This proposed cheminformatic framework can predictively enhance formulation design and the development of cosmeceutical treatments to interact favorably with the skin microbiome.

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Monday 24 March 2025, 8 PM, San Diego Convention Center, Hall B2/C, SciMix

American Chemical Society National Meeting, San Diego, CA, 23 – 27 March 2025

Cheminformatic Approach to Predictive Modelling Cosmeceutical Formulations Based on Skin Microbiome Chemical Interactions

Yae-won Michelle Jung, Jennifer Uyanga, AJ Addae, and Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry, Bioengineering, and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA

Topical skincare products and cosmeceuticals interact with the skin microbiome, popularly termed the “second skin.” The composition of an individual’s skin microbiome depends on various factors, such as age, gender, skin tone, and can also vary across different regions of the body. Additionally, environmental stressors such as frequency of sun exposure, humidity, and pollution can influence an individual’s skin microbiome. Previous studies have linked the skin’s microbiome diversity and commensal and pathogenic bacteria composition to the onset and presence of chronic skin conditions such as psoriasis and atopic dermatitis. Despite this phenomenon, profiling the behavior of the skin microbiome in response to cosmeceutical treatments is challenging. To address this, we propose that profiling the chemical behavior of the skin microbiome in response to widely used cosmeceutical treatments can enhance the predictions of efficacy, biofilm interactions, and tolerability challenges faced by modern cosmeceuticals.

Utilizing a cheminformatic framework, we link the efficacy of commonly utilized cosmeceutical materials (Vitamin C, retinol, niacinamide, and alpha-hydroxy acids) and their interactions with the skin microbiome through cosmeceutical-induced pH changes of bacterial biofilms, bacterial diversity, and other biological markers after topical application of products. By systematically cataloging the chemical properties of the microbiome under a range of application conditions noted in previous literature, we can predict improvements in epidermal health through known interactions of cosmeceutical materials with skin microbiome viability. This proposed cheminformatic framework can predictively enhance formulation design and the development of cosmeceutical treatments to interact favorably with the skin microbiome.

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Tuesday 25 March 2025, 4²⁰ PM, Room 28A San Diego Convention Center

American Chemical Society National Meeting, San Diego, CA, Tom Mallouk 70^th Birthday (INOR) Symposium, 23 – 27 March 2025

Discovering and Leveraging Long-Range Interactions in Natural and Synthetic Molecular Assemblies

Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry, Bioengineering, and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA

One of the key advances in nanoscience and nanotechnology has been our increasing ability to reach the limits of atomically precise structures. By having developed the “eyes” to see, to record spectra, and to measure function at the nanoscale, we have been able to fabricate structures with precision as well as to understand the important and intrinsic interactions in these assemblies. By being able to peer below the exposed surface, we have discovered surprising and significant interactions that result in long-range ordering, surface passivation, and impact on surface chemistry. We explore the roles of these interactions and how they might be leveraged to advantage in chemistry, materials, and devices.

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Wednesday 26 March 2025, 9 AM

American Chemical Society National Meeting, San Diego, CA, PMSE: Polymer-Derived Self- and Directed Assembly of Nanoparticles: Unprecedented Functionalities Stemming from Their Collective Synergetic Properties, 23 – 27 March 2025

Cage-Molecule Self-Assembly and Atomically Precise Cluster Assemblies

Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry, Bioengineering, and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA

Self-assembled cage molecules offer opportunities to test chemical, physical, and materials properties because within families of molecules, they form identical lattices. Thus, properties such as atomic arrangements within the cage, molecular and surface dipoles, band alignment, and functional group placement can all be controlled. We describe atomic-scale measurements of coordination and valency, dipole-dipole interactions, hydrogen bonding, band alignment, dimensional effects on pK_a, thermal conductivity, and spin. We demonstrate how modest electric fields can be used to produce dramatic shifts in electronic, thermal, and spin properties using polyaromatic and thus highly polarizable atomically precise clusters. We discuss how this level of control might be used to advantage technologically and how it relates to conduction in nature.

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Thursday 27 March 2025, 8⁵⁰ AM, Marina Ballroom, Salon G, San Diego Marriot Marquis

American Chemical Society National Meeting, San Diego, CA, 23 – 27 March 2025

Novel Zinc Oxide UV Filter Nanohybrid Network for Multifunctional Photoprotection and Photostability in Sunscreen Formulations

AJ Addae,¹ Jennifer Uyanga,¹ Yogendra Kumar Mishra,² Joey Chifamba,³ Justin Caram,¹ Paul S. Weiss¹^,4,5,6

1. Department of Chemistry and Biochemistry, University of California, Los Angeles
2. Mads Clausen Institute, NanoSYD, University of Southern Denmark
3. Department of Pharmaceutical Sciences, University of Zimbabwe
4. California NanoSystems Institute, University of California, Los Angeles
5. Department of Bioengineering, University of California, Los Angeles
6. Department of Materials Science and Engineering, University of California, Los Angeles

In the United States, sunscreens are regulated as both a drug and a cosmetic. New sunscreen UV filters have not been approved by the United States Food and Drug Administration (US FDA) for commercial use since 1999, which limits cosmetic chemists to develop sunscreens within the limitations of the current filters available. This investigation focuses on zinc oxide (ZnO), as it is the most widely used UV filter and is classified as generally recognized as safe and effective (GRASE). Because sunscreens are complex emulsion systems that require sustained photostability, emulsion stability, and cosmetic elegance, sunscreen compositions face significant limitations that hinder their efficiency and application. Additionally, commercially available sunscreens often struggle with non-uniform UV absorption when applied onto the skin, causing uneven photoprotection.

We discuss the synthesis, observed nanohybrid network, and optical properties of flame-synthesized zinc oxide tetrapods as a UV filter in hydrocarbon-rich suspensions for sunscreen formulations. We first detail the challenges of metal oxide UV filters in sunscreens and their impacts on the sunscreen’s emulsion and photostability. We demonstrate that the unique tetrapod shape of ZnO, fabricated without wet chemistry methods, affords more enhanced photoprotective and cosmetic advantages to sunscreen formulations than other common ZnO nanoparticle morphologies. We compare aggregation and agglomeration of ZnO tetrapods in sunscreens versus ZnO obtained by wet chemistry methods, and the impacts of such aggregation and agglomeration on the sunscreen’s emulsion, and resulting photoprotective properties. Finally, we propose an updated framework for assessing the stability of sunscreen emulsions for consumer use.

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Thursday 27 March 2025

Hamline University, 3M/Ronald A. Mitsch Lectures in Chemistry, St. Paul, MN

Mimicking Nature: Controlling Charge, Heat, and Spin at Interfaces

Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry, Bioengineering, and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA

One of the key advances in nanoscience and nanotechnology has been our increasing ability to reach the limits of atomically precise structures. By having developed the “eyes” to see, to record spectra, and to measure function at the nanoscale, we have been able to fabricate structures with precision as well as to understand the important and intrinsic heterogeneity of function found in these assemblies. The physical, electronic, mechanical, thermal, and chemical connections that materials make to one another and to the outside world are critical. Just as the properties and applications of conventional semiconductor devices depend on these contacts, so do nanomaterials, many nanoscale measurements, and devices of the future. We explore the important roles that these contacts can play in preserving key transport and other properties. Initial nanoscale connections and measurements guide the path to future opportunities and challenges ahead. Band alignment, minimally disruptive connections, and control of spin and heat are all targets and can be characterized in both experiment and theory. I discuss our initial forays into this area in a number of materials systems.

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Friday 28 March 2025

Hamline University, 3M/Ronald A. Mitsch Lectures in Chemistry, Public Lecture, St. Paul, MN

From Moving Atoms to Medicine: Exploring the Nanoscale World

Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry, Bioengineering, and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA

Biology functions at the nanoscale. Thus, there are special opportunities not only to make biological measurements using nanotechnology, but also to interact directly in order to influence biological outcomes. I describe how we fabricate and use nanostructures to advance high-throughput gene editing for cellular therapies targeting genetic diseases and cancer immunotherapy. We exploit molecular recognition and phase transitions to create molecular treadmills to grow three-dimensional co-cultured tissue efficiently for personalized medicine, testing potential therapeutics, and growing meat and fish sustainably. Nanoscience and nanotechnology developed from chemistry, physics, biology, engineering, medicine, toxicology, and a host of other fields. Along the way, we taught each other our problems, challenges, and approaches. The interdisciplinary communication skills that were developed and are now part of our training remain unique to the field. As a result, nanoscience contributes to a wide range of other fields, such as neuroscience, the microbiome, oncology, cellular agriculture, and more.

 

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Monday 7 – Friday 11 April 2025

Materials Research Society National Meeting, Seattle WA, Symposium on Protons in Solids, Fluids, and Molecules, 7 – 11 April 2025

Measuring and Leveraging Local Structures in Materials for Hydrogen Storage and Reactions

Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry, Bioengineering, and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA

We measure the local structure in materials, such as Pd  and MXenes, that have been proposed for hydrogen storage, usage, and reactions. The specific interactions at and near vacancies, adsorbates, and defects can vary substantially from the pristine material. By using combinations of scanning probe microscopies and spectroscopies, closely coupled to theory, we are able to determine local electronic and structural effects, as we build a comprehensive picture of how to optimize these materials for hydrogen storage and other chemistries.

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Monday 28 April 2025

Tulane University, Department of Chemistry, New Orleans, LA

Mimicking Nature: Controlling Charge, Heat, and Spin at Interfaces

Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry, Bioengineering, and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA

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Sunday 3 – Thursday 8 August 2025

Gordon Research Conference on Electron Spin Interactions with Chiral Molecules and Materials, Southern New Hampshire University, Hooksett, NH, 3-8 August 2025

Mimicking Nature: Controlling Charge, Heat, and Spin

Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry, Bioengineering, and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA

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Monday 8 – Friday 12 August 2025

3^rd International Conference on Nanotechnologies and Bionanoscience, Heraklion, Crete, Greece, 8-12 September 2025

TBA

Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry, Bioengineering, and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA

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Monday 9 – Wednesday 11 March 2026

nano.Israel, Tel Aviv, Israel, 9 – 11 March 2025

Understanding and Controlling Charge, Heat, and Spin at Atomically Precise Interfaces

Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry, Bioengineering, and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA