No abstract

A reverse micelle based approach is reported for the synthesis of BaCO3 nanowires with lengths up to 100 μm and diameters as small as 10−30 nm, each of which is a continuous single crystal with the c-axis along the wire length axis. The synthesis is achieved by the reaction of barium and carbonate ions solubilized in the polar cores of nonionic reverse micelles of C12E4 (tetraethylene glycol monododecyl ether) in cyclohexane. The crystal growth of BaCO3 nanowires has been examined by electron microscopy observations, and a directional aggregation process is proposed for the nanowire formation.

Eight members of the Ag/1,2,4-triazole/polyoxometalates (POMs) hybrid supramolecular family, namely, [Ag4(dmtrz)4][Mo8O26] (dmtrz=3,5-dimethyl-1,2,4-triazole, 1), [Ag6(3atrz)6][PMo12O40]2.H2O (3atrz=3-amino-1,2,4-triazole, 2), [Ag2(3atrz)2]2[HPMoVI10MoV2O40] (3), [Ag2(dmtrz)2]2[HPMoVI10MoV2O40] (4), [Ag2(trz)2]2[Mo8O26] (trz=1,2,4-triazole, 5), [Ag2(3atrz)2][Ag2(3atrz)2(Mo8O26)] (6), [Ag4(4atrz)2Cl][Ag(Mo8O26)] (4atrz=4-amino-1,2,4-triazole, 7), and [Ag5(trz)4]2[Ag2(Mo8O26)].4H2O (8), were synthesized through hydrothermal reactions of 1,2,4-triazole or its derivatives with appropriate silver salts and molybdates. Crystal structure analysis reveals that the POM-dependent Ag-1,2,4-triazolate units in these hybrid compounds form a novel tetranuclear cluster (1), a unique double calix[3]arene-shaped hexamer (2), zigzag chains (5 and 6), helix chains (3, 4, and 8), and an interesting looped chain (7). A series of hydrogen bonding-based supramolecular assemblies varying among the 0-D+0-D (1 and 2), 0-D+1-D (3 and 4), 1-D+1-D (5 and 7), and 1-D+2-D (6) modes between the organomatic cations and POM anions were observed in these structures. Moreover, the inorganic chain [Ag(Mo8O26)]n3n- in 7 constructed by the building block [Mo8O26]4- linked only via single Ag+ ion is unprecedented. Compound 8 is the first high-dimensional framework constructed from the [Ag2(Mo8O26)]n2n- rod-shaped subunits. These hybrid supramolecular compounds present interesting photochemical properties. The spectroscopic experiments show that they not only are potential semiconductor materials but also have interesting photoluminescence phenomena, including O-->Mo [LMCT] and intraligand [pi-pi*] emissions generated by internal heavy metal effect.

No abstract

The designed sensor enables accurate reconstruction of chest-wall movement caused by cardiopulmonary activities, and the algorithm enables estimation of respiration, heartbeat rate, and some indicators of heart rate variability (HRV). In particular, quadrature receiver and arctangent demodulation with calibration are introduced for high linearity representation of chest displacement; 24-bit ADCs with oversampling are adopted for radar baseband acquisition to achieve a high signal resolution; continuous-wavelet filter and ensemble empirical mode decomposition (EEMD) based algorithm are applied for cardio/pulmonary signal recovery and separation so that accurate beat-to-beat interval can be acquired in time domain for HRV analysis. In addition, the wireless sensor is realized and integrated on a printed circuit board compactly. The developed sensor system is successfully tested on both simulated target and human subjects. In simulated target experiments, the baseband signal-to-noise ratio (SNR) is 73.27 dB, high enough for heartbeat detection. The demodulated signal has 0.35% mean squared error, indicating high demodulation linearity. In human subject experiments, the relative error of extracted beat-to-beat intervals ranges from 2.53% to 4.83% compared with electrocardiography (ECG) R-R peak intervals. The sensor provides an accurate analysis for heart rate with the accuracy of 100% for p = 2% and higher than 97% for p = 1%.

No abstract

Mesoporous silica spheres ranging from 2 to 6 µm in size were synthesized under static acidic conditions by mixed cationic-nonionic surfactant templating. The mesoporous structure of the calcined silica microspheres was characterized by X-ray diffraction (XRD) and nitrogen sorption, whereas the morphology and size of the microspheres were revealed by scanning electron microscopy (SEM). It was shown that stirring is unfavorable for the formation of silica spheres in the present synthesis. The growth of the micrometer-sized mesoporous silica spheres was examined by transmission electron microscopy (TEM), and an undirectional aggregation process was proposed for the formation of these spheres.

No abstract