Synthesis and Photophysics of Cyclometalated Ir(III) Complexes with Novel 4-Substituted-2-Phenyl-Pyridine Ligands

This thesis reports the design, synthesis and photophysical characterisation of a series of novel cyclometalated iridium complexes with 4-substituted-2-phenyl-pyridine ligands. A synthetic strategy based on preparation of 4-substituted pyridine and subsequent phenylation was applied, and related challenges, for instance, the preparation of 4-(4’(-iodo-2’,3’,5’,6’-tetramethylphenyl)pyridine from 1,4-diiododurene, low yields of the Sonogashira reactions due to the steric hindrance and low yields of phenylation reactions with phenyl lithium have been overcome. Photophysical studies show that the π-conjugation of iridium complexes broken by rotating the 4-substituents out of plane, and this kind of complexes exhibit similar emission spectra to the unsubstituted parent compound Ir(ppy)2(acac). C4 shows an extremely long luminescence lifetime for a complex of this type, and the nature of this characteristic may be due to the triplet energy being distributed between the ligand and the metal centre

GameEval: Evaluating LLMs on Conversational Games

The rapid advancements in large language models (LLMs) have presented challenges in evaluating those models. Existing evaluation methods are either reference-based or preference based, which inevitably need human intervention or introduce test bias caused by evaluator models. In this paper, we propose GameEval, a novel approach to evaluating LLMs through goal-driven conversational games, overcoming the limitations of previous methods. GameEval treats LLMs as game players and assigns them distinct roles with specific goals achieved by launching conversations of various forms, including discussion, question answering, and voting. We design three unique games with cooperative or adversarial objectives, accompanied by corresponding evaluation metrics, to show how this new paradigm comprehensively evaluates model performance.Through extensive experiments, we show that GameEval can effectively differentiate the capabilities of various LLMs, providing a comprehensive assessment of their integrated abilities to solve complex problems. Our public anonymous code is available at https://github.com/GameEval/GameEval

Friction-induced nanofabrication method to produce protrusive nanostructures on quartz

In this paper, a new friction-induced nanofabrication method is presented to fabricate protrusive nanostructures on quartz surfaces through scratching a diamond tip under given normal loads. The nanostructures, such as nanodots, nanolines, surface mesas and nanowords, can be produced on the target surface by programming the tip traces according to the demanded patterns. The height of these nanostructures increases with the increase of the number of scratching cycles or the normal load. Transmission electron microscope observations indicated that the lattice distortion and dislocations induced by the mechanical interaction may have played a dominating role in the formation of the protrusive nanostructures on quartz surfaces. Further analysis reveals that during scratching, a contact pressure ranged from 0.4Py to Py (Py is the critical yield pressure of quartz) is apt to produce protuberant nanostructures on quartz under the given experimental conditions. Finally, it is of great interest to find that the protrusive nanostructures can be selectively dissolved in 20% KOH solution. Since the nanowords can be easily 'written' by friction-induced fabrication and 'erased' through selective etching on a quartz surface, this friction-induced method opens up new opportunities for future nanofabrication

Fabrication mechanism of friction-induced selective etching on Si(100) surface

As a maskless nanofabrication technique, friction-induced selective etching can easily produce nanopatterns on a Si(100) surface. Experimental results indicated that the height of the nanopatterns increased with the KOH etching time, while their width increased with the scratching load. It has also found that a contact pressure of 6.3 GPa is enough to fabricate a mask layer on the Si(100) surface. To understand the mechanism involved, the cross-sectional microstructure of a scratched area was examined, and the mask ability of the tip-disturbed silicon layer was studied. Transmission electron microscope observation and scanning Auger nanoprobe analysis suggested that the scratched area was covered by a thin superficial oxidation layer followed by a thick distorted (amorphous and deformed) layer in the subsurface. After the surface oxidation layer was removed by HF etching, the residual amorphous and deformed silicon layer on the scratched area can still serve as an etching mask in KOH solution. The results may help to develop a low-destructive, low-cost, and flexible nanofabrication technique suitable for machining of micro-mold and prototype fabrication in micro-systems

DragNUWA: Fine-grained Control in Video Generation by Integrating Text, Image, and Trajectory

Controllable video generation has gained significant attention in recent years. However, two main limitations persist: Firstly, most existing works focus on either text, image, or trajectory-based control, leading to an inability to achieve fine-grained control in videos. Secondly, trajectory control research is still in its early stages, with most experiments being conducted on simple datasets like Human3.6M. This constraint limits the models' capability to process open-domain images and effectively handle complex curved trajectories. In this paper, we propose DragNUWA, an open-domain diffusion-based video generation model. To tackle the issue of insufficient control granularity in existing works, we simultaneously introduce text, image, and trajectory information to provide fine-grained control over video content from semantic, spatial, and temporal perspectives. To resolve the problem of limited open-domain trajectory control in current research, We propose trajectory modeling with three aspects: a Trajectory Sampler (TS) to enable open-domain control of arbitrary trajectories, a Multiscale Fusion (MF) to control trajectories in different granularities, and an Adaptive Training (AT) strategy to generate consistent videos following trajectories. Our experiments validate the effectiveness of DragNUWA, demonstrating its superior performance in fine-grained control in video generation. The homepage link is \url{https://www.microsoft.com/en-us/research/project/dragnuwa/

Influence of sulfur oxidation state and substituents on sulfur-bridged luminescent copper(I) complexes showing thermally activated delayed fluorescence

C.M.B. thanks Dr. Maria B. Ezhova for helpful discussions regarding NMR spectra, and Dr. Saeid Kamal for assistance with the TCSPC data. C.M.B. and M.O.W. acknowledge the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Peter Wall Institute for Advanced Studies for financial support and the Laboratory for Advanced Spectroscopy for Imaging Research (LASIR) for facilities access. Z.X. thanks Compute Canada for computing resources for DFT calculations. C.L. thanks the Prof. & Mrs. Purdie Bequests Scholarship and AstraZeneca PhD Studentship. E.Z.-C. and I.D.W.S thank EPSRC (grants EP/R035164/1 and EP/L017008/1) for financial support.Copper(I) complexes are seen as more sustainable alternatives to those containing metal ions such as iridium and platinum for emitting devices. Copper(I) complexes have the ability to radiatively decay via a thermally activated delayed fluorescence (TADF) pathway, leading to higher photoluminescent quantum yields. In this work we discuss six new heteroleptic Cu(I) complexes of the diphosphine–diimine motif. The diphosphine ligands employed are (oxydi- 2,1-phenylene)bis(diphenylphosphine) (DPEPhos) and the diimine fragments are sulfur- bridged dipyridyl ligands (DPS) which are functionalized at the 6,6′-positions of the pyridyl rings (R = H, Me, Ph), and have varying oxidation states at the bridging sulfur atom (S, SO2). The proton ( Cu-DPS, Cu-DPSO2 ) and phenyl ( Cu-Ph-DPS, Cu-Ph-DPSO2 ) substituted species are found to form monometallic complexes, while those with methyl substitution ( Cu-Me-DPS, Cu-Me-DPSO2 ) are found to have a “Goldilocks” degree of steric bulk leading to bimetallic species. All six Cu(I) complexes show emission in the solid state, with the photophysical properties characterized by low temperature steady-state and time-resolved spectroscopies and variable temperature time-correlated single photon counting (TCSPC). Cu- DPS , Cu-DPSO2 , Cu-Me-DPS , Cu-Me-DPSO2 and Cu-Ph-DPSO2 were shown to emit via a TADF mechanism, while Cu-Ph-DPS showed photoluminescence properties consistent with triplet ligand-centered (3LC) emission.PostprintPeer reviewe

Live-dead assay on unlabeled cells using phase imaging with computational specificity

Existing approaches to evaluate cell viability involve cell staining with chemical reagents. However, the step of exogenous staining makes these methods undesirable for rapid, nondestructive, and long-term investigation. Here, we present an instantaneous viability assessment of unlabeled cells using phase imaging with computation specificity. This concept utilizes deep learning techniques to compute viability markers associated with the specimen measured by label-free quantitative phase imaging. Demonstrated on different live cell cultures, the proposed method reports approximately 95% accuracy in identifying live and dead cells. The evolution of the cell dry mass and nucleus area for the labeled and unlabeled populations reveal that the chemical reagents decrease viability. The nondestructive approach presented here may find a broad range of applications, from monitoring the production of biopharmaceuticals to assessing the effectiveness of cancer treatments

ManagerTower: Aggregating the Insights of Uni-Modal Experts for Vision-Language Representation Learning

Two-Tower Vision-Language (VL) models have shown promising improvements on various downstream VL tasks. Although the most advanced work improves performance by building bridges between encoders, it suffers from ineffective layer-by-layer utilization of uni-modal representations and cannot flexibly exploit different levels of uni-modal semantic knowledge. In this work, we propose ManagerTower, a novel VL model architecture that gathers and combines the insights of pre-trained uni-modal experts at different levels. The managers introduced in each cross-modal layer can adaptively aggregate uni-modal semantic knowledge to facilitate more comprehensive cross-modal alignment and fusion. ManagerTower outperforms previous strong baselines both with and without Vision-Language Pre-training (VLP). With only 4M VLP data, ManagerTower achieves superior performances on various downstream VL tasks, especially 79.15% accuracy on VQAv2 Test-Std, 86.56% IR@1 and 95.64% TR@1 on Flickr30K. Code and checkpoints are available at https://github.com/LooperXX/ManagerTower.Comment: Accepted by ACL 2023 Main Conference, Ora

Blue emissive cobalt(III) complexes and their use in the photocatalytic trifluoromethylation of polycyclic aromatic hydrocarbons

A.K.P and G.S.H thank Natural Sciences and Engineering Research Council of Canada. A.K.P thanks the Leverhulme Trust Early Career Fellowship (ECF-2017-326) and the University of St Andrews. The authors thank the Prof. & Mrs Purdie Bequests Scholarship and AstraZeneca support for C.L. EZ-C thanks the Engineering and Physical Sciences Research Council (EP/M02105X/1) and the University of St Andrews.The first examples of room temperature (r.t.) luminescent Co(III) complexes ( 1 and 2 ) are presented that exhibit intense ligand‐to‐metal and ligand‐to‐ligand charge transfer absorption in the low energy UV region (λabs ~ 360‐400 nm) and low‐negative quasi‐reversible reduction events (E1/2(red) = −0.58 V and −0.39 V vs. SCE for 1 and 2 , respectively). The blue emission of 1 and 2 at r.t. is due to the large bite angles and strong σ‐donation of the ligands, the combined effect of which helps to separate the emissive 3LMCT (triplet ligand‐to‐metal charge transfer) and the non‐emissive 3MC (triplet metal‐centered) states. 1 and 2 were found to be powerful photo‐oxidants (ECo(III)*/Co(II) = 2.26 V and 2.75 V vs. SCE of 1 and 2 , respectively) and were used as inexpensive photoredox catalysts for the regioselective mono(trifluoromethylation) of polycyclic aromatic hydrocarbons (PAHs) in good yields (~ 40‐58%).PostprintPeer reviewe