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liuqi98/README.md

AI for Science Research Portfolio

面向蛋白质工程与分子建模的 AI4Science 研究,关注几何表示、生成建模、物理约束学习、不确定性估计与跨蛋白泛化。

I work on machine learning methods for protein engineering and molecular modeling, with an emphasis on geometric representation learning, scientific priors, uncertainty, and out-of-distribution generalization.

Research focus

  • Protein representation learning — combining protein language models, structure-aware embeddings, local geometry, and mutation descriptors.
  • Scientific machine learning — encoding symmetry, antisymmetry, consistency, and other domain constraints into model objectives.
  • Generative modeling — inverse folding and flow-based approaches for sequence and structure generation.
  • Reliable prediction — probabilistic learning, uncertainty decomposition, protein-disjoint evaluation, and auditable experiments.

Selected work

ProteuSetGP — protein-balanced probabilistic learning for mutation effects

A structure-aware learning framework for single- and double-mutation stability prediction on unseen proteins.

  • Fuses ESM-2 sequence deltas, SaProt structural context, physicochemical changes, and local geometry.
  • Uses Pooling by Multihead Attention (PMA) for permutation-invariant mutation-set encoding.
  • Models single and double mutants with separate sparse variational Gaussian process (SVGP) heads.
  • Aligns training with scientific evaluation through protein-balanced sampling and within-protein RankNet pretraining.
  • Evaluated on protein-disjoint MegaScale splits across three seeds.
Task Protein-wise Spearman Pooled Spearman
Single mutants 0.7654 ± 0.0033 0.7152 ± 0.0035
Double mutants 0.6753 ± 0.0200 0.5533 ± 0.0030

Code and reproducibility · Manuscript and evidence package

PhyloPath — physics-constrained antibody evolutionary planning

A validated trajectory-planning framework for navigating measured antibody fitness landscapes while penalizing unfavorable intermediates. The frozen evaluation spans four antibody backgrounds and eight antibody--antigen tasks, with ablations, noise robustness analysis, machine-readable results, and a one-command audit covering 22 focused tests and manuscript regeneration.

  • Path-aware beam search improved fully monotonic trajectory rate over matched greedy search by 0.584 (antibody-cluster 95% CI 0.371--0.796).
  • Final measured gain improved by 0.087 (95% CI 0.058--0.108).
  • Negative results and the failed global-oracle gate are retained explicitly to keep the public claim boundary auditable.

Code, frozen results, and reproducibility package

DiMA-PPI State Potential — thermodynamically consistent mutation prediction

A compact manuscript and reproducibility bundle for a shared four-state potential model. The formulation enforces reverse-mutation antisymmetry and path additivity by construction, and includes strict-split, external-test, ablation, bootstrap, and path/cycle audits.

Code, manuscript, and reproducibility bundle

Algorithms and methods

The table distinguishes validated public work from research explorations so that project maturity is explicit.

Area Methods explored Scientific use Status
Protein representations ESM-2, SaProt, mutation-delta features, local structural descriptors Mutation-effect prediction and protein generalization Validated in public project
Set and ranking learning PMA, RankNet, protein/quantile-balanced sampling Variable-order mutations and imbalanced measurements Validated in public project
Probabilistic learning SVGP, predictive mean/variance, uncertainty-aware ranking Risk-aware mutation prioritization Validated in public project
Physics-constrained learning Antisymmetric ΔΔG objectives, state potentials, cycle consistency, path-aware planning Consistent mutation prediction and antibody evolutionary trajectories Validated in public projects
Geometric learning Molecular graphs, geometric GNNs, SE(3)-aware/equivariant representations Structure-conditioned molecular learning Research exploration
Conditional generation Antibody inverse folding, ProteinMPNN-style sequence design Structure-to-sequence generation Research exploration
Flow-based generation Flow matching and structure-aware generative models Molecular sequence/structure generation Research exploration
Distributional geometry Optimal transport on molecular representations and surfaces Comparing structured molecular distributions Research exploration
Reliability Uncertainty decomposition, structural identifiability, OOD evaluation Detecting ambiguous or unreliable predictions Research exploration

Research principles

  1. Evaluate at the scientific unit of generalization. Use protein-disjoint splits and protein-level metrics when the goal is performance on unseen proteins.
  2. Match the objective to the deployment question. Ranking, calibration, and balanced sampling can matter as much as architecture choice.
  3. Encode trustworthy structure. Scientific constraints should improve consistency without hiding empirical limitations.
  4. Keep claims auditable. Separate multi-seed results, ablations, controls, and exploratory findings.

Technical stack

Python · PyTorch · protein language models · graph and geometric deep learning · Gaussian processes · scientific data pipelines · reproducible experimentation

Current direction

I am developing AI4Science methods that connect protein foundation models with geometric and physics-informed learning for reliable protein design and mutation-effect prediction.

Pinned Loading

  1. DiMA-PPI-State-Potential DiMA-PPI-State-Potential Public

    Reproducibility bundle for thermodynamically consistent PPI mutation-effect prediction

    Python

  2. PhyloPath PhyloPath Public

    Physics-constrained trajectory planning on measured antibody fitness landscapes

    Python