Carbazolic Conjugated Organic Polymers for Visible-Light-Driven CO2 Photoreduction with H2 O to CO with High Efficiency and Selectivity.

Visible-light-driven CO2 photoreduction with H2 O to value-added chemicals in high efficiency and selectivity is significant but challenging. Herein, a series of carbazolic conjugated organic polymers (CB-COPs) with electron donor-acceptor (D-A) structures were prepared, which showed high efficiency for visible-light-driven photocatalytic reduction of CO2 with H2 O in a solid-gas mode, affording CO as the exclusive carbonaceous product. Especially, CB-COP-mpd derived from 3,5-di(9H-carbazol-9-yl)pyridine exhibited the highest CO evolution rate up to 191.46 µmol g-1 h-1 with a selectivity of 100 %. Mechanism studies showed that carbazolyl is a promising electron donor candidate for constructing CB-COPs with D-A structures, capable of improving the catalytic efficiency and suppressing H2 generation. The acceptor building block with excessive electron withdrawing capability was favorable to H2 O adsorption, thus resulting in the generation of H2 . This work provides new insights for designing COPs photocatalysts for CO2 photocatalytic reduction.

Effect of Exercise Volume on Plantar Microcirculation and Tissue Hardness in People With Type 2 Diabetes.

Objective: Exercise has been reported to be beneficial for people with type 2 diabetes (T2DM), but exercise, especially weight-bearing exercise, may increase the risk of diabetic foot ulcers (DFUs). This study aimed to explore the associations between different volumes of weight-bearing physical activities and plantar microcirculation and tissue hardness in people with T2DM. Methods: 130 elderly people with T2DM were enrolled for this cross-sectional study. They were classified into the high exercise volume group and the low exercise volume group based on their weekly energy expenditure (metabolic equivalents per week) in the past year. Weekly energy expenditure was calculated using the International Physical Activity Questionnaire and the Compendium of Physical Activities. The plantar oxygen saturation (SO2) and soft tissue hardness of each participant's right foot were measured. Results: A total of 80 participants completed the trial. The average exercise energy expenditure of the high exercise volume group and the low exercise volume group were significantly different (p < 0.05). The results showed that the SO2 of the high exercise volume group (67.25 ± 6.12%) was significantly higher than the low exercise volume group (63.75 ± 8.02%, p < 0.05). The plantar tissue hardness of the high exercise volume group was lower than the low exercise volume group in the big toe, midfoot and hindfoot regions (p < 0.05). Conclusion: This study demonstrates that higher volumes of exercise are associated with better plantar microcirculation and lower plantar tissue hardness in people with T2DM. The findings of this study indicate that weight-bearing exercise may not increase risk of developing diabetic foot ulcers.

The effects of different accumulated pressure-time integral stimuli on plantar blood flow in people with diabetes mellitus.

BACKGROUND: Exercise, especially weight-bearing exercise (e.g. walking), may affect plantar tissue viability due to prolonged repetitive high vertical and high shear pressure stimulus on the plantar tissue, and further induce development of diabetic foot ulcers (DFUs). This study aimed to investigate the effects of different accumulated pressure-time integral (APTI) stimuli induced by walking on plantar skin blood flow (SBF) responses in people with diabetes mellitus (DM). METHODS: A repeated measures design was used in this study. Two walking protocols (low APTI (73,000 kPa·s) and high APTI (73,000 × 1.5 kPa·s)) were randomly assigned to ten people with DM and twenty people without DM. The ratio of SBF measured by laser Doppler flowmetry after walking to that before (normalized SBF) was used to express the SBF responses. RESULTS: After low APTI, plantar SBF of people with DM showed a similar response to people without DM (P = 0.91). However, after high APTI, people with DM had a significantly lower plantar SBF compared to people without DM (P < 0.05). In people with DM, plantar SBF in the first 2 min after both APTI stimuli significantly decreased compared to plantar SBF before walking (P < 0.05). CONCLUSIONS: People with DM had a normal SBF response after low APTI walking but had an impaired SBF response after high APTI walking, which suggests that they should avoid weight-bearing physical activity with intensity more than 73,000 kPa·s and should rest for more than 2 min after weight-bearing physical activity to allow a full vasodilatory response to reduce risk of DFUs.

Modular synthesis of (C-10 to C-13)-substituted-9,14-diaryl-9,14-dihydrodibenzo[a,c]phenazines via a subsequent Buchwald-Hartwig amination and C-H amination strategy.

Herein, we report a modular synthetic approach of (C-10 to C-13)-substituted 9,14-diaryl-9,14-dihydrodibenzo[a,c]phenazine derivatives. This synthetic route enables the aromatic substitution in a predictable and programmed manner to obtain products in synthetically useful isolated yield.

Facile Synthesis of Nitrogen-Containing Six-Membered Benzofuzed Phenophosphazinine Oxides and Studies of the Photophysical Properties.

A facile synthesis of nitrogen-containing six-membered benzofuzed phosphacycles has been described. This cyclization reaction triggered by Tf2O provides an expedient protocol of phosphacycles with a simple operation at mild conditions. The preliminary photophysical studies of these novel materials reveal that the fluorescence intensity enhances with the molecular aggregation in the solid state and that the introduction of the sterically bulky phenanthrene group into the phosphacycles allows a significant increase in the fluorescence quantum yield.

A Joint Low-Power Cell Search and Frequency Tracking Scheme in NB-IoT Systems for Green Internet of Things.

As a dedicated communication protocol for Internet-of-Things, narrowband internet of things (NB-IoT) needs to establish the communication link rapidly and reduce retransmissions as much as possible to achieve low power consumption and stable performance. To achieve these targets, the low-power scheme of the initial cell search and frequency tracking is investigated in this paper. The cell search process can be subdivided into narrowband primary synchronization signal (NPSS) detection and narrowband secondary synchronization signal (NSSS) detection. We present an NPSS detection method whose timing metric is composed of symbol-wise autocorrelation and a dedicated normalization factor. After the detection of NPSS, the symbol timing and fractional frequency offset estimation is implemented in a resource-efficient way. NSSS detection is conducted in the frequency domain with a calculation-reduced algorithm based on the features of NSSS sequences. To compensate the accumulated frequency offset during uplink transmission, a pilot-aided rapid frequency tracking algorithm is proposed. The simulation results of the proposed cell search scheme are outstanding in both normal coverage and extended coverage NB-IoT scenarios, and the accumulated frequency offset can be estimated with high efficiency.