Songgu Wu

Solvent penetration mediated phase transformation for the preparation of aggregated particles with well-defined shape

We report here a unique method for the preparation of aggregated crystals with well-defined shape and size using a solvent penetration-mediated phase transformation. An unusually fast phase transformation of sulfadiazine was observed. The aggregated sulfadiazine crystals are obtained through a water penetration mediated transformation of sulfadiazine N-methyl pyrrolidone solvate. The aggregated particles keep the same shape and size of the parent crystals.

Two novel cocrystals of lamotrigine with isomeric bipyridines and in situ monitoring of the cocrystallization

Abstract Crystal engineering strategy was applied to develop new solid forms of lamotrigine. Two novel cocrystals of lamotrigine forming with 4,4′‐bipyridine (2:1) and 2,2′‐bipyridine cocrystal (1:1.5) were successfully obtained by neat grinding and liquid assisted grinding. The novel cocrystals were fully characterized and confirmed by X‐ray diffraction, thermal and spectroscopic analysis. DXRxi Raman microscope was also used to identify the cocrystals. The factors such as solvent and the structure of coformers which influenced the cocrystal formation were discussed. Furthermore, the novel cocrystals were both obtained by slurry crystallization. Process analytical technologies including focused beam reflectance measurement and attenuated total reflectance Fourier Transform Infrared were applied to investigate the cocrystallization process and the mechanism. HPLC analysis showed that the dissolution rate and the solubility of the two novel cocrystals were both improved. Graphical abstract Figure. No Caption available.

Low-power high-efficiency architecture for low-complexity chase soft-decision Reed-Solomon decoding

Algebraic soft-decision decoding (ASD) of Reed–Solomon (RS) codes can obtain significant coding gain over the hard-decision decoding with polynomial complexity. Compared with other ASD algorithms, the low-complexity chase (LCC) decoding testing 2η test vectors has less computation complexity with similar or better coding gain. To reduce the latency of the interpolation, one major step of the LCC decoding, multiple interpolators can be applied and the pipelined architecture is usually adopted to make the throughput of the decoder higher. However, for application specific integrated circuit (ASIC) implementation and practical applications, the area and power consumption of the pipelined decoder are not preferable. This study proposes a modified serial LCC decoder architecture which reduces the power consumption and hardware requirement while keeping the shortest critical path as one adder, one multiplexer and one multiplier. As major contributions of this study, a novel re-encoder and erasure decoder block and an improved way to compute syndromes are proposed to reduce the whole latency of the decoder. For a (458, 410) RS code over Galois Field (GF)(210) with η=8, the hardware requirement and power consumption of the proposed LCC decoder are reduced by 23 and 25% than those of the common pipelined counterparts, respectively.

Polymorphs of daidzein and intermolecular interaction effect on solution crystallization

Daidzein (DAID), known as a phytoestrogen, is an important bioactive flavonoid isolated from soybean and pueraria. However, its poor solubility and low dissolution rate limit its clinical application. With the aim of finding a form with fit-for-purpose physicochemical properties, a comprehensive solid-state screening experiment was performed. As a result, three polymorphs were discovered and the single crystal structure of stable form II was revealed for the first time. Form II was obtained in solvents with high β and π* values, while form III was produced under opposite conditions. To clarify this phenomenon, intermolecular interactions were investigated through single crystal structure analysis, solvent property analysis and computational methods. The results demonstrated that the compact arrangement of DAID and the solvents used played a critical role in solution crystallization. Moreover, the physicochemical properties of these three polymorphs were fully characterized, and the powder dissolution behavior was determined in pure water and pH 1.2 and pH 6.8 buffer solutions. The newly discovered form II exhibited better thermal stability, lower moisture sorption and faster dissolution rate compared with the other forms.