Thu 29 Feb 18:45: Otters in Cambridgeshire To be added to the mailing list to receive the login for Zoom events, email webmaster [at] cnhs.org.uk
Abstract not available
To be added to the mailing list to receive the login for Zoom events, email webmaster [at] cnhs.org.uk
- Speaker: Peter Pilbeam
- Thursday 29 February 2024, 18:45-20:30
- Venue: Main Seminar Room (First Floor) David Attenborough Building, University of Cambridge Pembroke St, Cambridge CB2 3QZ.
- Series: Cambridge Natural History Society; organiser: events.
Thu 22 Feb 18:45: Indonesia, Alfred Wallace and Krakatoa To be added to the mailing list to receive the login for Zoom events, email webmaster [at] cnhs.org.uk
Abstract not available
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- Speaker: Olwen Williams
- Thursday 22 February 2024, 18:45-20:30
- Venue: Main Seminar Room (First Floor) David Attenborough Building, University of Cambridge Pembroke St, Cambridge CB2 3QZ.
- Series: Cambridge Natural History Society; organiser: events.
Modulating the electronic structure of Ni(OH)2 by coupling with low-content Pt for boosting urea oxidation reaction enables significantly promoted energy-saving hydrogen production
DOI: 10.1039/D3EE03398H, PaperMengxiao Zhong, Meijiao Xu, Siyu Ren, Weimo Li, Ce Wang, Mingbin Gao , Xiaofeng Lu
Replacing high-potential oxygen evolution reaction (OER) by the low-potential nucleophiles oxidation reaction (NOR) is an essential way to further promote the production rate of hydrogen during water electrolysis. Here, low-content...
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Solid Additive Dual‐Regulates Spectral Response Enabling High‐Performance Semitransparent Organic Solar Cells
Semi-transparent organic solar cells (ST-OSCs) possess significant potential for applications in vehicles and buildings due to their distinctive visual transparency. Conventional device engineering strategies are typically used to optimize photon selection and utilization at the expense of power conversion efficiency (PCE); moreover, the fixed spectral utilization range always impose an unsatisfactory upper limit to its light utilization efficiency (LUE). In this study, a novel solid additive 1,3-diphenoxybenzene (DB) has been employed to dual-regulate donor/acceptor molecular aggregation and crystallinity, which effectively broadens the spectral response of resulting device in near-infrared region. Besides, more visible light was allowed to pass through the devices, which enables ST-OSCs to possess satisfactory photocurrent and high average visible transmittance (AVT) simultaneously. The inclusion of DB also results in a multi-scale phase-separated morphology and effectively suppresses voltage losses. Consequently, the optimal ST-OSCs based on PP2+DB/BTP-eC9+DB achieves a superior LUE of 4.77%, with an AVT of 42.98% and a PCE of 11.10%, representing the highest value within AVT range of 40–50% observed thus far. Such results indicate that the ST-OSCs can simultaneously meet the requirements for minimum commercial efficiency and plant photosynthesis when integrated with the roofs of agricultural greenhouses. This work emphasizes the significance of additives to tune the spectral response in ST-OSCs, and charts the way for organic photovoltaics in economically sustainable agricultural development.
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Wed 20 Mar 16:00: Title to be confirmed
Abstract not available
- Speaker: Gordon Brown (University of Warwick)
- Wednesday 20 March 2024, 16:00-17:00
- Venue: Nick Mackintosch Room, Department of Psychology, Downing Site.
- Series: Social Psychology Seminar Series (SPSS); organiser: Yara Kyrychenko.
Mon 11 Mar 11:00: Title to be confirmed NOTE: This talk is on Monday at 11 am !
Abstract not available
NOTE: This talk is on Monday at 11 am !
- Speaker: Eran Halperin (Hebrew University)
- Monday 11 March 2024, 11:00-12:00
- Venue: Ground Floor Lecture Theatre, Department of Psychology, Downing Site, Cambridge.
- Series: Social Psychology Seminar Series (SPSS); organiser: Yara Kyrychenko.
Wed 07 Feb 14:30: Homotopy methods for convex optimization
Convex optimization concerns the problem of finding the maximum of a linear function over a convex set. This class covers many optimization problems in quantum information, portfolio optimization, and machine learning.
In this talk, we will introduce a new approach to solving convex optimization problems via a homotopic approach. In this approach, we deform an optimization problem with a trivial solution into the target problem and keep track of the solutions along the homotopy. This is motivated by the field of numerical algebraic geometry, which solves systems of polynomial equations using a similar idea.
We show that our method applies to certain convex optimization problems, including Semidefinite Programs, Hyperbolic Programs, and convex optimization problems with a single convexity constraint. Moreover, we present several benchmark problems in which this method outperforms known methods.
- Speaker: Andreas Klingler (Innsbruck)
- Wednesday 07 February 2024, 14:30-15:30
- Venue: Centre for Mathematical Sciences MR11, CMS.
- Series: CCIMI Seminars; organiser: Hamza Fawzi.
Thu 08 Feb 18:45: Pollinator Conservation – and your Lawn To be added to the mailing list to receive the login for Zoom events, email webmaster [at] cnhs.org.uk
Morgan Morrison is researching pollinator conservation at Royal Holloway, University of London.
She will talk about her PhD research which covers all aspects of pollinator conservation, from bees, butterflies and hoverflies to disease, protected areas and citizen science.
Morgan will cover questions about “Are diseases spillover from honeybees to wild bee?” all the way to “How can citizens help pollinators all from the comfort of their lawns?”.
She will also be introducing a citizen science study taking place in summer with which you could help.
To be added to the mailing list to receive the login for Zoom events, email webmaster [at] cnhs.org.uk
- Speaker: Morgan Morrison, Researcher, Royal Holloway, University of London
- Thursday 08 February 2024, 18:45-20:30
- Venue: Main Seminar Room (First Floor) David Attenborough Building, University of Cambridge Pembroke St, Cambridge CB2 3QZ.
- Series: Cambridge Natural History Society; organiser: events.
Thu 01 Feb 11:00: Thermodynamic Integration, fermion sign problem, and real-space renormalization
As non-specialists in renormalization, we have tried to understand Sect VI of the famous 1975 Review of Modern Physics by K. G. Wilson that has remained cryptic to many. I will discuss a practical and un-biased Monte Carlo algorithm that we have implemented for the two-dimensional Ising model. Inspired by the original numerical method, it integrates modern twists in sampling, and that might be useful in other contexts (work with K. Sathwik). *disclaimer!
- Speaker: Werner Krauth, ENS Paris, Oxford
- Thursday 01 February 2024, 11:00-12:00
- Venue: Mott Seminar Room (531).
- Series: Theory of Condensed Matter; organiser: Gaurav.
Tailoring Built‐in Electric Field in a Self‐Assembled Zeolitic Imidazolate Framework/MXene Nanocomposites for Microwave Absorption
The use of heterointerface engineering, which can play a pivotal role in producing advanced microwave-absorbing materials, to prepare a zeolitic imidazolate framework (ZIF)–MXene nanocomposite is reported herein. The ZIF–MXene composites can be prepared by electrostatic self-assembly of negatively charged titanium carbide MXene flakes and positively charged Co-containing ZIF nanomaterials. This approach effectively creates abundant Mott–Schottky heterointerfaces exhibiting a robust built-in electric field (BIEF) effect, as evidenced by experimental and theoretical analyses, leading to a notable attenuation of electromagnetic energy. Systematic manipulation of the BIEF-exhibiting heterointerface, achieved through topological modulation of the ZIF, proficiently alters charge separation, facilitates electron migration, and ultimately enhances polarization relaxation loss, resulting in exceptional electromagnetic wave absorption performance (reflection loss RL min = −47.35 dB and effective absorption bandwidth f E = 6.32 GHz). The present study demonstrates an innovative model system for elucidating the interfacial polarization mechanisms and pioneers a novel approach to developing functional materials with electromagnetic characteristics through spatial charge engineering.
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Anti‐inflammatory Peptide‐Conjugated Silk Fibroin/Cryogel Hybrid Dual Fiber Scaffold with Hierarchical Structure Promotes Healing of Chronic Wounds
Chronic wounds resulting from diabetes, pressure, radiation therapy, and other factors continue to pose significant challenges in wound healing. To address this, our study introduces a novel hybrid fibroin fibrous scaffold (FFS) comprising randomly arranged fibroin fibers and vertically aligned cryogel fibers (CF). The fibroin scaffold was efficiently degummed at room temperature and simultaneously formed a porous structure. The aligned cryogel fibers were produced via directional freeze-drying, achieved by controlling solution concentration and freezing polymerization temperature. The incorporation of aligned cryogel fibers into the expanded fibroin fiber scaffold led to enhanced cell infiltration both in vitro and in vivo, further elevating the hybrid scaffold's tissue compatibility. We also conjugated the anti-inflammatory peptide 1 (AP-1) to the hybrid fibrous scaffold, effectively transforming the inflammatory status of chronic wounds from pro-inflammatory to pro-reparative. Consequently, the FFS-AP1+CF group demonstrated superior granulation tissue formation, angiogenesis, collagen deposition, and re-epithelialization during the proliferative phase compared to the commercial product PELNAC. Moreover, the FFS-AP1+CF group displayed epidermis thickness, numbers of regenerated hair follicles, and collagen density closer to normal skin tissue. Our findings highlight the potential of random fibroin fibers/aligned cryogel fibers hybrid fibrous scaffold as a promising approach for skin tissue filling and tissue regeneration.
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A Hybrid Pulsed Laser Deposition Approach to Grow Thin Films of Chalcogenides
Vapor-pressure mismatched materials such as transition metal chalcogenides have emerged as electronic, photonic, and quantum materials with scientific and technological importance. However, epitaxial growth of vapor-pressure mismatched materials are challenging due to differences in the reactivity, sticking coefficient, and surface adatom mobility of the mismatched species constituting the material, especially sulfur containing compounds. Here, we report a novel approach to grow chalcogenides – hybrid pulsed laser deposition – wherein an organosulfur precursor is used as a sulfur source in conjunction with pulsed laser deposition to regulate the stoichiometry of the deposited films. Epitaxial or textured thin films of sulfides with variety of structure and chemistry such as alkaline metal chalcogenides, main group chalcogenides, transition metal chalcogenides and chalcogenide perovskites are demonstrated, and structural characterization reveal improvement in thin film crystallinity, and surface and interface roughness compared to the state-of-the-art. The growth method can be broadened to other vapor-pressure mismatched chalcogenides such as selenides and tellurides. Our work opens up opportunities for broader epitaxial growth of chalcogenides, especially sulfide-based thin film technological applications.
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Tue 13 Feb 13:10: Crime and Punishment: Rethinking Right Wing Authoritarianism
Abstract: Right wing authoritarianism (RWA) is a political psychology construct proposed by Duckitt (2009) and refined by Gerber and Jackson (2016), purported to account for a spectacular proportion of variance in punitiveness. We beg to differ. We challenge the validity of punitiveness measures used by existing research and fail to reproduce an effect of RWA on punitive attitudes when using a more robust measure of punitiveness, as measured by a large representative population survey from several Central European countries. Latent variable analysis of responses to a range of sentencing vignettes challenged the idea that there is a single underlying “punitiveness” construct, an assumption that underpins existing RWA research. Latent class analysis, however, revealed patterns in sentencing preferences. RWA in isolation was not predictive of subjects’ sentencing class. Rather, the effect of RWA was suppressed by other political psychology measures. That is, RWA was only significant when other measures were added to the model. We critically discuss the assumptions of the RWA construct in the context of our findings and set new directions for the research into the root causes of punitive sentiments.
- Speaker: Malia Marks, Criminology
- Tuesday 13 February 2024, 13:10-14:00
- Venue: Richard King room, Darwin College.
- Series: Darwin College Humanities and Social Sciences Seminars; organiser: Dr Stefanie Ullmann.
Tue 06 Feb 13:10: Making Space for the Future: Imagining the Smart Nation in Singapore
Through an ethnography of two “Smart Nation” smart home projects in Singapore, I detail how state planners project and replicate future imaginaries through the smart city by repeatedly materialising them in smart urban infrastructure. These historically-rooted planning practices project some residents as representing and productive of national futures while excluding others. Residents repeatedly and materially engage with these imaginaries, sometimes replicating and sometimes reimagining them, through everyday embodied engagement with smart urban infrastructures.
I show how these residents disrupt and create un-accounted for data flows in their daily lives, focusing on racial minorities, queer residents, and noncitizens for whom data flows mean continued exclusion from national futures. I argue that overemphasis on visible protest in public space neglects the impacts of these quotidian acts of political resistance, particularly in highly surveilled contexts. Analysing instead how differentiated residents navigate their “technological everyday” (Amin 2007) by spatialising “geographic counter-stories” (Kobayashi 2005), I argue, shows how state power is expressed and experienced through smart urban infrastructure. It also illuminates residents’ agency in co-producing smart city futures, constructing their senses of self and nation, and practicing (smart) citizenship.
- Speaker: Amelia Hassoun, Minderoo Centre for Technology and Democracy
- Tuesday 06 February 2024, 13:10-14:00
- Venue: Richard King room, Darwin College.
- Series: Darwin College Humanities and Social Sciences Seminars; organiser: Dr Stefanie Ullmann.
Reversible Surface Engineering of Cellulose Elementary Fibrils: From Ultralong Nanocelluloses to Advanced Cellulosic Materials
Cellulose nanofibrils (CNFs) are supramolecular assemblies of cellulose chains that provide outstanding mechanical support and structural functions for cellulosic organisms. However, traditional chemical pretreatments and mechanical defibrillation of natural cellulose produce irreversible surface functionalization and adverse effects of morphology of the CNFs, respectively, which limits the utilization of CNFs in nanoassembly and surface functionalization. Herein, we present a facile and energetically efficient surface engineering strategy to completely exfoliate cellulose elementary fibrils from various bioresources, which provides CNFs with ultrahigh aspect ratios (∼1400) and reversible surface. During the mild process of swelling and esterification, the crystallinity and the morphology of the elementary fibrils were retained, resulting in high yields (98%) with low energy consumption (12.4 kJ g−1). In particular, on the CNF surface, the surface hydroxyl groups were restored by removal of the carboxyl moieties via saponification, which offers a significant opportunity for reconstitution of stronger hydrogen bonding interfaces. Therefore, the resultant CNFs can be used as sustainable building blocks for construction of multi-dimensional advanced cellulosic materials, e.g., 1D filaments, 2D films and 3D aerogels. The proposed surface engineering strategy provides a new platform for fully utilizing the characteristics of the cellulose elementary fibrils in the development of high-performance cellulosic materials.
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Realizing the high thermoelectric performance of highly preferentially oriented SnSe based nanorods via band alignment
DOI: 10.1039/D3EE04109C, PaperYaru Gong, Pan Ying, Qingtang Zhang, Yuqi Liu, Xinqi Huang, Wei Dou, Yujing Zhang, Di Li, Dewei Zhang, Tao Feng, Meiyu Wang, Guang Chen, Guodong Tang
Polycrystalline SnSe is considered as a highly promising candidate for thermoelectric applications due to its facile processing, machinability and scale-up applications.
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Fri 02 Feb 13:00: Towards reconciling Cosmology, GR and QFT through non-perturbative Stochastic Inflation
In the context of inflation, we show how to account for quantum modes in general and numerical relativity on scales bigger than the Hubble radius, from where they behave classically and can grow non-perturbatively.
We provide a formulation of Stochastic Inflation in full general relativity that goes beyond the slow-roll and separate universe approximations. Starting from the initial conditions problem in numerical relativity, we show how gauge invariant Langevin source terms can be obtained for the complete set of Einstein equations in their ADM formulation by providing a recipe for coarse-graining the spacetime in any small gauge. These stochastic source terms are defined in terms of the only dynamical scalar degree of freedom in single-field inflation and all depend simply on the first two time derivatives of the coarse-graining window function, on the gauge-invariant mode functions that satisfy the Mukhanov-Sasaki evolution equation, and on the slow-roll parameters.
We validate the efficacy of these Langevin dynamics directly using an example in uniform field gauge, obtaining the stochastic e-fold number without the need for a first-passage-time analysis. As well as investigating the most commonly used gauges in cosmological perturbation theory, we also derive stochastic source terms for the coarse-grained first-order BSSN formulation of Einstein’s equations, which enables a well-posed implementation for 3+1 numerical relativity simulations.
Based on https://arxiv.org/abs/2401.08530v1
- Speaker: Yoann Launay, DAMTP, University of Cambridge
- Friday 02 February 2024, 13:00-14:00
- Venue: Potter room/Zoom.
- Series: DAMTP Friday GR Seminar; organiser: Xi Tong.
Electro‐Optical Multi‐Classification Platform for Minimizing Occasional Inaccuracy in Point‐of‐Care Biomarker Detection
On-site diagnostic tests that accurately identify disease biomarkers lay the foundation for self-healthcare applications. However, these tests routinely rely on single-mode signals and suffer from insufficient accuracy, especially for multiplexed point-of-care tests within a few minutes. Here, we develop a dual-mode multi-classification diagnostic platform that integrates an electrochemiluminescence sensor and a field-effect transistor sensor in a microfluidic chip. The microfluidic channel guides the testing samples to flow across electro-optical sensor units, which produce dual-mode readouts by detecting infectious biomarkers of Mycobacterium tuberculosis, human rhinovirus, and group B streptococcus. Then, machine-learning classifiers generate three-dimensional hyperplanes to diagnose different diseases. Dual-mode readouts derived from distinct mechanisms enhance the anti-interference ability physically, and machine-learning-aided diagnosis in high-dimensional space reduces the occasional inaccuracy mathematically. Clinical validation studies with 501 unprocessed samples indicate that the platform has an accuracy approaching 99%, higher than the 77%∼93% accuracy of rapid point-of-care testing technologies at 100% statistical power (> 150 clinical tests). Moreover, the diagnosis time is 5 minutes without a trade-off of accuracy. This work solves the occasional inaccuracy issue of rapid on-site diagnosis, endowing POCT systems with the same accuracy as laboratory tests and holding unique prospects for complicated scenes of personalized healthcare.
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Mechanically and Thermally Robust Gel Electrolytes Built from A Charged Double Helical Polymer
Polymer electrolytes have received tremendous interest in the development of solid-state batteries, but often fall short in one or more key properties required for practical applications. Herein, we report a rigid gel polymer electrolyte prepared by immobilizing a liquid mixture of a lithium salt and poly(ethylene glycol) dimethyl ether with only 8 wt% poly(2,2′-disulfonyl-4,4′-benzidine terephthalamide) (PBDT). The high charge density and rigid double helical structure of PBDT lead to formation of a nanofibrillar structure that endows this electrolyte with stronger mechanical properties, wider temperature window, and higher battery rate capability compared to all other poly(ethylene oxide) (PEO)-based electrolytes. We systematically study the ion transport mechanism in this rigid polymer electrolyte using multiple complementary techniques. Li/LiFePO4 cells show excellent capacity retention over long-term cycling, with thermal cycling reversibility between ambient temperature and elevated temperatures, demonstrating compelling potential for solid-state batteries targeting fast charging at high temperatures and slower discharging at ambient temperature.
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Molecular Engineering Enables Hydrogel Electrolyte with Ionic Hopping Migration and Self‐Healability Toward Dendrite‐Free Zinc Metal Anodes
Hydrogel electrolytes (HEs), characterized by intrinsic safety, mechanical stability, and biocompatibility, can promote the development of flexible aqueous zinc-ion batteries (FAZIBs). However, current FAZIB technology is severely restricted by the uncontrollable dendrite growth arising from undesirable reactions between the HEs with sluggish ionic conductivity and Zn metal. To overcome this challenge, this work proposes a molecular engineering strategy, which involves the introduction of oxygen-rich poly(urea-urethane) (OR-PUU) into polyacrylamide (PAM)-based HEs. The OR-PUU/PAM HEs facilitate rapid ion transfer through their ionic hopping migration mechanism, resulting in uniform and orderly Zn2+ deposition. The abundant polar groups on the OR-PUU molecules in OR-PUU/PAM HEs break the inherent H-bond network, tune the solvation structure of hydrated Zn2+, and inhibit the occurrence of side reactions. Moreover, the interaction of hierarchical H-bonds in the OR-PUU/PAM HEs endows them with self-healability, enabling in-situ repair of cracks induced by plating/stripping. Consequently, Zn symmetric cells incorporating the novel OR-PUU/PAM HEs exhibit a long cycling life of 2000 h. The resulting Zn–MnO2 battery displays a low capacity decay rate of 0.009% over 2000 cycles at 2000 mA g−1 . Overall, this work provides valuable insights to facilitate the realization of dendrite-free Zn-metal anodes through the molecular engineering of HEs.
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