Multiple errors correction for position-limited DNA sequences with GC balance and no homopolymer for DNA-based data storage.

Deoxyribonucleic acid (DNA) is an attractive medium for long-term digital data storage due to its extremely high storage density, low maintenance cost and longevity. However, during the process of synthesis, amplification and sequencing of DNA sequences with homopolymers of large run-length, three different types of errors, namely, insertion, deletion and substitution errors frequently occur. Meanwhile, DNA sequences with large imbalances between GC and AT content exhibit high dropout rates and are prone to errors. These limitations severely hinder the widespread use of DNA-based data storage. In order to reduce and correct these errors in DNA storage, this paper proposes a novel coding schema called DNA-LC, which converts binary sequences into DNA base sequences that satisfy both the GC balance and run-length constraints. Furthermore, our coding mode is able to detect and correct multiple errors with a higher error correction capability than the other methods targeting single error correction within a single strand. The decoding algorithm has been implemented in practice. Simulation results indicate that our proposed coding scheme can offer outstanding error protection to DNA sequences. The source code is freely accessible at https://github.com/XiayangLi2301/DNA.

[Reconstruction of soft-tissue defect in the middle and distal thirds of the leg with the soleus muscle flap].

OBJECTIVE: To investigate the efficacy of surgical method with the soleus muscle flap for repairing the soft-tissue defects in the middle and distal thirds of the leg, combined with open tibial fracture and/or osteomyelitis. METHODS: From May 2007 to December 2011, 8 cases with soft-tissue defects in the middle and distal thirds of the leg were treated with soleus muscle flaps, including 5 cases with chronic osteomyelitis and 3 cases with open tibial fracture and acute osteomyelitis. The defects size ranged from 8 cm x 6 cm to 12 cm x 10 cm. The surface of muscle flaps was covered by split-thickness skin graft. The defects at the donor site were closed directly. RESULTS: All the muscle flaps and skin grafts survived completely and fracture was healed. The patients were followed up for 2 to 54 months with satisfactory cosmetic and functional results. CONCLUSIONS: The soleus muscle flap is an effective and feasible method for reconstruction of the soft-tissue defects in the middle and distal thirds of the leg, combined with open tibial fracture and/or osteomyelitis. The morbidity at donor sites is also minor.