OIL/WATER NANOEMULSION BIODISTRIBUTION IN MICE UPON INTRAVENOUS ADMINISTRATION

The present study aimed to explore the biodistribution of O/W nanoemulsions (NE) upon intravenous administration. Three NEs were prepared with distinctive droplet sizes: SE (29 ± 1 nm), ME (214 ± 2 nm) and LE (883 ± 16 nm) without overlapping of the size distribution. Kolliphor® HS15 was used as the only surfactant for these three NEs, so that their droplets had similar surface structure. The NEs droplet size was stable under room temperature for minimum 3 days in phosphate buffer saline (PBS) and in mice plasma in vitro for 4-hour at 37°C. A lipophilic fluorescent dye, 1, 1’-dioctadecyl-3, 3, 3’, 3’-tetramethylindocarbocyanine perchlorate (DiI) was selected as the probe and loaded in the SE, ME and LE (designated thereafter as DSE, DME and DLE, respectively). A fluorometry for DiI was established with a linear range of 1.0-1000 ng/mL. The processing procedure and assay method for biological samples were developed. DiI extraction efficiency was 74.6-93.4%, depending on the tissues. For the biodistribution study, tumor-bearing mice received intravenous injection of DiI (2-5 mg/kg) in free solution (DS) or in the NEs via tail vein. The mice were sacrificed at sampling time points and the biological samples were assayed for DiI concentrations. DS manifested early tissues peak concentration (apparent Tmaxs at 0.5 h) followed by rapid decline, with tissue recovery mainly from the liver, spleen and lungs. DSE had a comparable plasma profile as DS but lower concentrations in the spleen and lungs as compared to the corresponding tissue profiles followed by the administration of DS. DME showed a sustained plasma circulation and a long-term non-specific higher tissue uptake with significant accumulation in the heart, lung, liver and spleen. DLE displayed a favorable accumulation in the RES organs including the lung, spleen, and liver. In conclusion, the present study demonstrates that O/W NE exhibits altered biodistribution upon intravenous administration. And these features may be utilized as a targeted drug delivery and drug redisposition strategy

Hierarchical Transformer with Spatio-Temporal Context Aggregation for Next Point-of-Interest Recommendation

Next point-of-interest (POI) recommendation is a critical task in location-based social networks, yet remains challenging due to a high degree of variation and personalization exhibited in user movements. In this work, we explore the latent hierarchical structure composed of multi-granularity short-term structural patterns in user check-in sequences. We propose a Spatio-Temporal context AggRegated Hierarchical Transformer (STAR-HiT) for next POI recommendation, which employs stacked hierarchical encoders to recursively encode the spatio-temporal context and explicitly locate subsequences of different granularities. More specifically, in each encoder, the global attention layer captures the spatio-temporal context of the sequence, while the local attention layer performed within each subsequence enhances subsequence modeling using the local context. The sequence partition layer infers positions and lengths of subsequences from the global context adaptively, such that semantics in subsequences can be well preserved. Finally, the subsequence aggregation layer fuses representations within each subsequence to form the corresponding subsequence representation, thereby generating a new sequence of higher-level granularity. The stacking of encoders captures the latent hierarchical structure of the check-in sequence, which is used to predict the next visiting POI. Extensive experiments on three public datasets demonstrate that the proposed model achieves superior performance whilst providing explanations for recommendations. Codes are available at https://github.com/JennyXieJiayi/STAR-HiT

OFDMA/SC-FDMA aided space-time shift keying for dispersive multi-user scenarios

Motivated by the recent concept of Space-Time Shift Keying (STSK) developed for achieving a flexible diversity versus multiplexing gain trade-off, we propose a novel Orthogonal Frequency Division Multiple Access (OFDMA)/Single Carrier Frequency Division Multiple Access (SC-FDMA) aided multi-user STSK scheme for frequency-selective channels. The proposed OFDMA/SC-FDMA STSK scheme is capable of providing an improved performance in dispersive channels, while supporting multiple users in a multiple antenna aided wireless system. Furthermore, the scheme has the inherent potential of benefitting from the low-complexity single-stream Maximum-likelihood (ML) detector. Both an uncoded and a sophisticated near-capacity coded OFDMA/SC-FDMA STSK scheme were studied and their performances were compared in multiuser wideband Multiple-Input Multiple-Output (MIMO) scenarios. Explicitly, OFDMA/SC-FDMA aided STSK exhibits an excellent performance even in the presence of channel impairments due to the frequency-selectivity of wideband channels and proves to be a beneficial choice for high capacity multi-user MIMO systems