Fig. 4From: Open-source QSAR models for pKa prediction using multiple machine learning approachesDNN learning model for pKa prediction. The model was comprised of a four-layer neural network with one input layer (K features), three hidden layers (256 nodes each) and one output layer (pKa value). Each hidden layer was followed by a batch normalization layer and a dropout layer (not shown). Connections existed between neurons across layers, but not within a layerBack to article page