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Summary It is highly attractive to develop efficient methods to directly extract Li from seawater to secure the supply of Li. However, high concentration of Na in the seawater poses a great challenge in Li extraction. Here, we developed pulsed-rest and pulse-rest-reverse pulse-rest electrochemical intercalation methods with TiO2-coated FePO4 electrodes for Li extraction. The method can lower the intercalation overpotential and successfully boost the Li selectivity. Moreover, the pulse-rest-reverse pulse-rest method can also promote electrode crystal structure stability during the co-intercalation of Li and Na and prolong the lifetime of the electrode. We demonstrated 10 cycles of successful and stable Li extraction with 1:1 of Li to Na recovery from authentic seawater, which is equivalent to the selectivity of ∼1.8 × 104. Also, with lake water of higher initial Li/Na ratio of 1.6 × 10−3, we achieved Li extraction with more than 50:1 of Li to Na recovery.

When the Kuroshio passes Green Island off Taiwan, well-organized wakes are formed by the interaction between the Kuroshio and the island. The vertical mixing in the wake produces cold water, which entrains from the mixed layer below the surface and results in relatively colder and saltier waters with a higher chlorophyll-a concentration on the sea surface to the lee of the island. The meander of the Kuroshio maximum velocity axis has a major influence on the island wake. The shift of the Kuroshio in front of Green Island not only weakens the flow velocity but also affects the development of the wake. In the Green Island wake, the density overturns with a Thorpe scale between 2.9 m and 20.5 m and the turbulent kinetic energy dissipation rate is 0.2 × 10−6–8.5 × 10−5 W kg−1, which corresponds to an eddy diffusivity in the range of 0.01–0.23 m2 s−1. The spatial distribution patterns of the sea surface temperature (SST) in the island wake are classified into four distinct types, as obtained from moderate-resolution imaging spectroradiometer (MODIS) SST images. The most frequently occurring type is of the wake alone, which accounts for 86.7% of the island wake patterns. The other three types are a wake with a tail stretching downstream (4.0%), a wake with a small cyclonic cold core but no tail stretching downstream (6.8%) and an S-shaped meandering wake (2.5%).

The interaction of coastal water in I-Lan Bay, a bay near northeast Taiwan, and the Kuroshio Current is studied using the data from hydrologic survey and satellite remote sensing. An index for water mass distinguished is used for clarifying the origin of water mass in I-Lan Bay. The velocity profile from acoustic Doppler current profile data indicates a countercurrent that flows southward along the northeast coast of Taiwan toward I-Lan Bay with a speed around 0.1–0.2 m/s. The index of water mass indicates that the water of I-Lan Bay is mainly affected by the northern shelf waters of Taiwan and mixed with Kuroshio nearshore water, thus forming a clear ocean front between these two areas. The near surface water temperature in the I-Lan Bay is about 2 °C lower than that in the Kuroshio region. The seasonal average near surface salinity of I-Lan Bay can exist 0.4 psu fresher than the Kuroshio area. From the analysis of dynamic process, the coastal countercurrent in I-Lan Bay is primarily affected by 1) the occurrence of cold dome in northeast of Taiwan mainly occurs in summer, and 2) the wind-driven current from the Taiwan Strait along the north coast and the northeast coast of Taiwan caused by the southwesterly monsoon makes the countercurrents strongly in summer. The dynamics of the countercurrent occurrence can be explained by the Ekman transport theory.

In this study, we used satellite imagery to conduct a statistical study of the ocean vortex train induced by the Kuroshio Current on the leeward side of Green Island, Taiwan. The spatial scale and characteristics of the ocean vortex train were analyzed using image datasets from five different high-resolution satellites, including optical imagery from the Satellite Pour l'Observation de la Terre and the Formosat-2 satellites and synthetic aperture radar imagery from the European Remote Sensing Satellite, Advanced Land Observing Satellite, and Sentinel-1. Satellite altimetry data and a moored acoustic Doppler current profiler (ADCP) were used to calculate the velocity of the Kuroshio Current. The ADCP data suggest that the velocity increases on the western side of the vortex train when it is formed on the leeward side of Green Island. Data from the moderate-resolution imaging spectroradiometer (MODIS) showed that the sea surface temperature of the recirculation water was over 2 °C colder and the chlorophyll-a concentration was two times higher than that of the surrounding waters. These phenomena suggested upwelling, mixing processes, and an island-mass effect. Wind forcing had a pronounced effect on the characteristics of the vortex train. High-resolution satellite images indicate that the averaged aspect ratio of the vortex train is 2.09 and the dimensionless width is 2.02 under southerly winds, compared to 1.91 and 2.76, respectively, under northerly winds.

Summary Excessive phosphorus in water is the primary culprit for eutrophication, which causes approximately $2.2 billion annual economic loss in the United States. This study demonstrates a phosphate-selective sustainable method by adopting Garcinia subelliptica leaves as a natural bio-template, where MgMn-layered double hydroxide (MgMn-LDH) and graphene oxide (GO) can be grown in situ to obtain L-GO/MgMn-LDH. After calcination, the composite shows a hierarchical porous structure and selective recognition of phosphate, which achieves significantly high and recyclable selective phosphate adsorption capacity and desorption rate of 244.08 mg-P g−1 and 85.8%, respectively. The detail variation of LDHs during calcination has been observed via in situ transmission electron microscope (TEM). Moreover, the roles in facilitating phosphate adsorption and antimicrobial ability of chemical constituents in Garcinia subelliptica leaves, biflavonoids, and triterpenoids have been investigated. These results indicate the proposed bio-templated adsorbent is practical and eco-friendly for phosphorus sustainability in commercial wastewater treatment., Graphical Abstract, Highlights • A natural bio-template provides hierarchical porous structure • The variation of nanostructure during thermal process is discussed in detail • The composite shows high sorption, selectivity, stability, and sustainability, Environmental Chemical Engineering; Green Chemistry; Natural Material

With the increasing packaging density and multi-functionality, thermal management and electromagnetic pollution in electronic devices are crucial. In this work, we propose a novel method to in-situ grow hollow Fe3O4 sphere (h-Fe3O4, inner and outer diameter of 870 nm and 975 nm, respectively) onto three-dimensional graphene foam (GF) surface and then filled it with polydimethylsiloxane (PDMS) to fabricate nanocomposites with high electromagnetic interference shielding effectiveness (70.37 dB from 8.2 to 12.4 GHz) and thermal conductivity (28.12 ± 1.212 W m−1 K−1) at room temperature. Moreover, conductive networks inside composites show super-flexible performance with high electrical conductivity (84.02 ± 8.385 S cm−1). The effect of in-situ growth hollow Fe3O4 spheres in the enhancement of EMI SE has been demonstrated via comparing with different contents, morphologies and preparation processing. Besides, the mechanism of thermal conductivity has been investigated by FEM simulation and theoretical modeling. Finally, the usage of GF/h-Fe3O4/PDMS composites as thermal interface materials (TIMs) for chip cooling is proved to be successful, and the corresponding temperature under usage power density is accurately predicted. These comprehensive properties of GF/h-Fe3O4/PDMS composite open a potential application for next-generation TIMs in chip packaging.

An annealing twinned Ag–4Pd binary alloy wire has been produced as an alternate material for a previously developed Ag–8Au–3Pd ternary alloy wire to meet requirements for high electrical conductivity and low cost. The electrical resistivity of this annealing twinned Ag-alloy bonding wire decreased drastically from the original value of 3.5 μΩ cm to about 2.9 μΩ cm after aging at 600 °C for 30 min. The decrease in electrical resistivity became moderate with longer aging times. In contrast to the apparent increase in grain size in a conventional Ag–4Pd wire during aging at 600 °C for various times, the grains in this annealing twinned wire grew much more slowly. The breaking load and elongation of this annealing twinned Ag–4Pd wire are also higher than those of conventional wire. The conventional grained Ag–4Pd wire has a slightly higher electrical resistivity of 3.7 μΩ cm than that of annealing twinned wire. However, the more rapid grain growth in the conventional grained Ag–4Pd wire led to a lower electrical resistivity than that of annealing twinned wire during aging process.

Introduction to Computer Science (ICS), which is a compulsory theoretical course for freshmen of the electrical engineering (EE) department, lays the foundation for more advanced courses. Nevertheless, since ICS covers a wide variety of concepts that are difficult to completely comprehend, incomplete understanding and a loss of learning incentive are possible problems. The aim of implementing hands-on practice (HOP) activities was to prepare the students for the actual hardware manipulation in the field of EE and also to enhance their performance in the future advanced practice courses. Through organizing optional evening hands-on practice (HOP) activities, this study investigated whether the first-year college students who participated in HOP would exhibit a better understanding in ICS compared to those who did not. The enrollment in HOP was optional in which the performance did not affect the score in the ICS course. The results showed that HOP participants not only had significantly higher academic scores (p < 0.05), but were also less stressed toward the ICS course (p < 0.05) than the non-participants. The former also showed increased interest in accepting challenges (e.g. Two HOP participants later entered the National Microcomputer Design Competition and were awarded the third prize). In conclusion, the introduction of optional HOP for freshmen of electrical engineering not only alleviated the stress that they face in response to the ICS course, but also improved the students' academic performance and class attendance rate as well as raising their interest and boosting their confidence in further challenges in the field of electrical engineering.

A portable Raman analyzer with a fiber-optic probe was first used to rapidly screen and identify the cocrystal formation between drug and coformer. Indomethacin (IMC) and anhydrous theophylline (TP) were selected as model drugs, but saccharin (SAC) and anhydrous citric acid (CA) were chosen as model coformers. The cocrystal formation that occurred in the solid-state IMC–SAC or TP–CA system via mechanical grinding process was investigated. Differential scanning calorimetry (DSC) was also used to investigate the possible cocrystal formation. The present study indicates that this new portable fiber-opticRaman spectroscopic technique was an easy and fast “real-time” method to screen and identify the progressive cocrystal formation in solid-state IMC–SAC or TP–CA system in the process of mechanical grinding by inserting the probe directly into the ground mixtures.

Using frequency and rank order statistics (FROS), this study analyzed the fluctuations in arterial waveform amplitudes recorded from an air pressure sensing system before and after reactive hyperemia (RH) induction by temporary blood flow occlusion to evaluate the vascular endothelial function of aged and diabetic subjects. The modified probability-weighted distance (PWD) calculated from the FROS was compared with the dilatation index (DI) to evaluate its validity and sensitivity in the assessment of vascular endothelial function. The results showed that the PWD can provide a quantitative determination of the structural changes in the arterial pressure signals associated with regulation of vascular tone and blood pressure by intact vascular endothelium after the application of occlusion stress. Our study suggests that the use of FROS is a reliable noninvasive approach to the assessment of vascular endothelial degeneration in aging and diabetes.

A simultaneous differential scanning calorimetry–Fourier transform infrared (DSC–FTIR) microspectroscopy was used to quickly investigate the co-crystal formulation between anhydrous theophylline (TP) and anhydrous citric acid (CA) in a one-step procedure. The raw materials of TP and CA, as well as the intact TP–CA co-crystal prepared by slow solvent evaporation were also respectively examined by this approach. The result indicates that the TP–CA co-crystal formulation was easily induced using this DSC–FTIR technique. The thermal-dependent changes in three-dimensional FTIR spectral contour profiles were started from 165 °C to induce the co-crystal formation of TP–CA, which was prior to the endothermic peak at 173 °C found in the conventional DSC curve. Beyond 165 °C, several new IR absorption peaks at 3515, 3124, 1730, 1710, 1677, 1648, 1552 and 1265 cm −1 corresponding to unique IR spectral peaks of intact TP–CA co-crystal were observed. The DSC–FTIR microspectroscopic results also evidenced the dimer–monomer transition of CA, but there were no markedly changes for TP or intact TP–CA co-crystal before its fusion. This strongly implies that the DSC–FTIR technique giving spectroscopic and thermodynamic information could simultaneously induce and identify the TP–CA co-crystal formation and phase transition of samples. Different storage conditions affecting the stability of both physical mixture and ground mixture of TP–CA were also determined. The physical mixture of TP–CA after storing at 55 °C/75% RH condition for one day was fast transformed to TP–CA co-crystal, indicating that TP–CA co-crystal was easily induced under accelerated storage condition. While the co-crystal formed from TP–CA ground mixture was stable in both 25 °C/75% RH and 55 °C/75% RH conditions.

To investigate the thermal behavior of cocrystal formed between anhydrous theophylline (TP) and anhydrous citric acid (CA) by neat manual cogrinding or thermal treatment, DSC and FTIR microspectroscopy with curve-fitting analysis were applied. The physical mixture and 60-min ground mixture were stored at 55{+-}0.5 Degree-Sign C/40{+-}2% RH condition to determine their stability behavior. Typical TP-CA cocrystals were prepared by slow solvent evaporation method. Results indicate that the cogrinding process could gradually induce the cocrystal formation between TP and CA. The IR spectral peak shift from 3495 to 3512 cm{sup -1} and the stepwise appearance of several new IR peaks at 1731, 1712, 1676, 1651, 1557 and 1265 cm{sup -1} with cogrinding time suggest that the mechanism of TP-CA cocrystal formation was evidenced by interacting TP with CA through the intermolecular O-H{center_dot}{center_dot}{center_dot}O hydrogen bonding. The stability of 60-min ground mixture of TP-CA was confirmed at 55{+-}0.5 Degree-Sign C/40{+-}2% RH condition over a storage time of 60 days. - Garphical abstract: Cogrinding, thermal and solvent-evaporation methods might easily induce the theophylline-citric acid cocrystal formation. Highlights: Black-Right-Pointing-Pointer Cogrinding process could gradually induce the cocrystal formation between TP and CA. Black-Right-Pointing-Pointer The TP-CA cocrystal was formed through the intermolecular O-H{center_dot}{center_dot}{center_dot}O hydrogen bonding. Black-Right-Pointing-Pointer Themore » 60-min TP-CA ground mixture was similar to the solvent-evaporated cocrystal. Black-Right-Pointing-Pointer The thermal-induced TP-CA cocrystal formation was confirmed by pre-heating the physical mixture to 152 Degree-Sign C. Black-Right-Pointing-Pointer The 60-min TP-CA ground mixture was stable at accelerated condition over a storage time of 60 days.« less

Partial shading is a commonly encountered issue in a PV (photovoltaic) system. In this paper, five different connection configurations of PV cells are studied to compare their performance under the condition of partial shading. They are SS (simple series), SP (series-parallel), TCT (total-cross-tied), BL (bridge-linked) and HC (honey comb) configurations. The electric network of each connection configuration is analyzed, taking into account the nonlinear nature of PV cells, by writing the Kirchhoff’s voltage and current equations. The analysis is followed by solving the simultaneous nonlinear equations using the Newton–Raphson algorithm, which allows the I–V (current–voltage) characteristic of the module with a specific configuration in response to different types and levels of partial shading to be evaluated. Comparison of the maximum power and fill factors of the five connection configurations is then carried out. Also studied is the reverse voltage across each PV cell. It is found that in most cases, the TCT configuration has a superior performance over the other four configurations in most comparison indices.

In this study we demonstrate a new composite oxide thin films of (MoO 3 ) 1 − x (V 2 O 5 ) x , x = 0, 0.01, 0.03, and 0.05, fabricated by pulsed laser deposition (PLD). The performance of platinum (Pt) catalyst activated hydrogen gas sensor with modified (MoO 3 ) 1 − x (V 2 O 5 ) x thin films were investigated. The thickness of the (MoO 3 ) 1 − x (V 2 O 5 ) x thin film is about 600–650 nm and its surface has a uniform morphology. Our results show that the gasochromic sensors prepared by (MoO 3 ) 0.99 (V 2 O 5 ) 0.01 thin film exhibited excellent hydrogen sensibility. The response and recovery time are in the range of 9–15 min for coloration and bleaching at room temperature under H 2 atmosphere. The results also show that (MoO 3 ) 1 − x (V 2 O 5 ) x /Pt (x = 0.01, 0.03, 0.05) thin films perform better gasochromic capability than the pristine MoO 3 /Pt sample.

Superconducting FeSe thin films were prepared at a substrate temperature of 320 °C by pulsed laser deposition. X-ray diffraction and transmission electron microscopic analyses showed that highly c-axis-orientated and high-quality films were obtained on various substrate materials, including single-crystal MgO, LaAlO 3 , SrTiO 3 and (100)-Si, and amorphous-SiO x , at such low temperature. From transport measurements all the films showed low-temperature structural phase transition at ∼60―90 K and superconducting transition at onset temperature varies from ∼7 K to

The present work reports on the fabrication of polymer light-emitting diodes by blending a small amount of poly(2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylene vinylene) (MEH-PPV) with poly(2,3-dibutoxy-1,4-phenylene vinylene) (DB-PPV). The optical spectra of the devices made of various ratios of the DB-PPV/MEH-PPV blends have shown that the inter-chain interactions of MEH-PPV chains were efficiently suppressed in the presence of DB-PPV as the host, resulting in the improvement of thermal stability and electroluminescence (EL) efficiency of the devices. The enhanced performance of the devices is attributed to the efficient Főrster energy transfer and charge trapping on the polymer blends of the DB-PPV/MEH-PPV host–guest system.

A phase transition was observed in the tetragonal FeSe superconductor under high pressure at around 2.55 GPa using X-ray scattering and Raman spectrum. From X-ray powder diffraction (XRD) experiments, the slope of the unit cell volume versus pressure curve change slightly at around 2.55–4 GPa, and the Bragg peaks of FeSe tetragonal phase disappear when the pressure reaches 11.4 GPa. We also found the superconducting transition temperature Tc increases and reaches a maximum value of ∼37 K at ∼3–4 GPa. The compressibility value ( dV / dP ) shows an abrupt change from 2.39 ( A 3 / GPa ) to 0.94 ( A 3 / GPa ) from pressure values of 0–2.55 GPa to 2.55–11.4 GPa. A similar phase transition was also observed in the Raman spectra under pressure.