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• Oblique-incidence reflectivity difference(OIRD) signals characters wax appearance temperature and the rate of change of crystallization process. • OIRD detection reveals the different stages of wax formation process. • OIRD is suitability for in situ probing of wax precipitation of different crude oils. Considering the negative effects of wax precipitation during petroleum transportation on flow assurance and profit loss, in this study, oblique-incidence reflectivity difference (OIRD) analysis is demonstrated to be a powerful tool for the in situ analysis of wax precipitation. Based on the hybrid detection of waxy oil and natural cooling, we develop a detailed wax precipitation model for waxy oil and demonstrate that it can be used to predict actual precipitation features, which are amenable to experimental validation. The curve trend of the OIRD detection exactly reveals the wax formation process, including nucleation, growth, and crystallization. The efficiency of this technique is proven by the fact that the OIRD signals provide the detailed characteristics of the wax precipitation, which include not only the wax appearance temperature (WAT) but also the rate of change of the crystallization process. The advantage of distinguishing between the different stages of the complex wax crystallization process with time and amplitude is demonstrated. [ABSTRACT FROM AUTHOR]

As new fluorescent materials, light wavelength conversion materials (light conversion agents) have attracted increasing attention from scientific researchers and agricultural materials companies due to their potential advantages in efficiently utilizing solar energy and increasing crop yield. According to the material properties, the light conversion agents can be divided into fluorescent dyes, organic rare-earth complexes, and inorganic rare-earth complexes. The current researches indicates that the fluorescent dyes have relatively high production costs, poor light stability, difficult degradation processes, and easily cause pollution to the ecological environment. The organic rare-earth complexes have short luminescence times, high production costs, and suffer from rapid decreases in luminescence intensity. Compared with fluorescent dyes and organic rare-earth complexes, although rare-earth inorganic complexes have high luminous efficiency, stable chemical properties, and better spectral matching performance, the existing inorganic light conversion agents have relatively poor dispersibility in agricultural films. According to the research on light conversion agents at home and abroad in recent years, this paper first introduces the three common light conversion agents, namely fluorescent dyes, organic rare-earth complexes, and inorganic rare-earth complexes, as well as their uses in agricultural films and their mechanisms of light conversion. At the same time, the preparation methods, advantages, disadvantages, and existing problems of various light conversion agents are classified and explained. Finally, we predict the development trends for light conversion agents in the future by considering six aspects, namely efficiency, cost, compatibility with greenhouse films, light matching, and light transmittance, in order to provide a reference for the preparation of stable and efficient light conversion agent materials. [ABSTRACT FROM AUTHOR]

A new series of Y-type polyurethanes containing different concentrations of nonlinear optical (NLO) chromophore with aniline donor and tricyanofurane (TCF) acceptor have been successfully prepared, and characterized by FTIR, UV-Vis, and 1H-NMR spectra. New polyurethanes were synthesized with different chromophore contents by introducing diol N, N-dihydroxyethylaniline or 4-[ N, N-(dihydroxyethyl)amino]benzaldehyde. These NLO polyurethanes exhibit good film forming property and high thermal stability up to 281°C. The highest electro-optic coefficient ( r33) of polymers is up to 39 pm V−1 measured by simple reflection technique at 1310 nm, and the temporal stability of the poling-induced order at elevated temperature of 80°C was much improved through the introducing of hydrogen bonding interaction in this system. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

A new nonlinear optical chromophore with strong electron-withdrawing acceptor and rigid-flexible dendron was synthesized. An electro-optic (EO) attenuated total reflectance modulator was prepared to measure the EO coefficient of the films. Modification of the tricyanopyrroline chromophore with rigid-flexible dendron group provided reduction of dipole-dipole interactions and improvement of its solubility. As the chromophore loading increased, there was a great improvement on the macroscopic EO response of the polymeric materials obtained by incorporating this chromophore as a guest in amorphous polycarbonate. The largest EO coefficient was 42 pm/V at 1310 nm. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

New tricyanopyrroline (TCP) chromophores with rigid-flexible dendron were prepared for second-order nonlinear optical (NLO) application. The chromophores were fully characterized using ultraviolet-visible spectroscopy, nuclear magnetic resonance spectroscopy and mass spectrometry. Thermal gravimetric analysis (TGA) revealed that the chromophores had excellent thermal stability. Large λ and high solvate chromic effects revealed that the chromophores had large second-order optical nonlinearity. The electro-optic coefficients ( r) were measured in the chromophores-doped poly(bisphenol A carbonate) films at the fundamental wavelength of 1310 nm, and the highest γ achieved was 217 pmV. Copyright © 2010 John Wiley & Sons, Ltd. Modification of the TCP chromophore with bulky groups provides reduction of dipole-dipole interactions, thus great improvement of the macroscopic electro-optic (EO) response was achieved by incorporating these chromophores as a guest into amorphous polycarbonate (APC). Furthermore, the modificated chromophore possesses good processability and exhibits high thermal decomposition temperature. [ABSTRACT FROM AUTHOR]

White pollution caused by agricultural films has recently attracted great attention. In some areas, the content of micro plastic in the soil has reached 30 kg/ha. The most effective way to solve this problem is to replace traditional polyethylene agricultural films with degradable agricultural films. The consistency between the degradation rate and the crop growth period has become the biggest obstacle for the wide application of such novel agricultural films. In this paper, crystallinity regulation is used to adjust the functional period of degradable agricultural films. In addition, an organic nucleating agent of polyethylenimine (PEI) is selected by doping it to poly(butylene adipate-co-terephthalate) (PBAT) polymers using a double-screw extruder. The PBAT doped with 1 wt% PEI films revealed a significant increase in mechanical properties, water holding capacity, and crystallinity compared with the pure PBAT film. There was a 31.9% increase in tensile strength, a 30.5% increase in elongation at break, a 29.6% increase in tear resistance, a 30.9% decrease in water vapor permeability, and a 3.1% increase in crystallinity. Furthermore, the induction period of PBAT doped with 1 wt% PEI under photoaging (without soil) was about 160 h longer than PBAT film, and the experienced biodegradation in soil (without light) was 1 week longer than PBAT film. Experimental results exhibited that the change of degradation degree was linearly proportional to the degree of crystallinity. This study proposes a convenient, low-cost, and effective method to adjust the crystallinity and change the degradation rate. [ABSTRACT FROM AUTHOR]

Energy, information, and materials are the three main factors required for the survival and development of modern humankind, with energy being the cornerstone of all development. In recent years, self-powered devices have received widespread attention. As a new generation device, Triboelectric nanogenerators (TENGs) assembled from flexible materials possess the characteristics of flexible design, low-cost, stable output performance, etc., and can be widely used in wearable and self-powered medical detection sensors of human body. In this paper, flexible bromobutyl rubber (BIIR) and PET were used as friction materials, and assembled into arched vertical contact-separation triboelectric nanogenerators following various film formation and surface roughening treatments. The treatment and assembly methods of the friction materials were studied in order to obtain the best power generating effects. In addition, due to the biocompatibility and intrinsic antibacterial property of BIIR films, the fabricated triboelectric nanogenerator was also applied to wearable self-powered sensor equipment, proving its potential in the fields of identification and gait analysis. The manuscript described the triboelectric nanogenerators assembled by bromobutyl rubber (BIIR) and PET, which has intrinsic antibacterial performance and high force detection sensitivity. It can be used in wearable and self-powered sensors. [Display omitted] • Ÿ Intrinsic antibacterial BIIR films were prepared by electrospinning and assembled into wearable and self - powered TENG. • Ÿ The BIIR-based TENGs is capable of energy-harvesting and signal recognition for identification and gait analysis. • The BIIR-based TENGs are easy to prepare and have the potential for large-scale industrial production. [ABSTRACT FROM AUTHOR]

Compared with traditional inorganic second-order nonlinear optical (NLO) materials, organic second-order NLO materials have many advantages in bandwidth, dielectric constant, half-wave voltage, electro-optic (EO) coefficients, processability, and material cost. Due to their potential applications in telecommunications, computing, detection, terahertz generation, and construction of functional photonic crystals, organic NLO materials have been widely studied for several decades. Currently, the poling efficiency and long-term stability are the largest obstacles for the application of organic NLO materials. At the molecular level, these problems are mainly caused by the strong dipole–dipole intermolecular interactions between the NLO chromophores with D-π-A structures. In the molecular design of the polymer system, modification of the chromophores is considered to be an efficient pathway to solve this problem. Since 2009, many studies have been performed by our group to reduce the strong dipole–dipole intermolecular interactions between the chromophores. In this review, the development of organic NLO materials in recent years is summarized, including the following: 1) a brief introduction of organic second-order NLO materials, 2) the requirements of NLO materials for applications in devices, 3) optimization of the first-order hyperpolarizability of NLO chromophores, 4) the optimization of the chromophore loading parameters (N, ), and 5) improvements of the stabilities of organic NLO materials. • Organic second order NLO materials was briefly introduced. • Requirements of NLO materials for applications in devices were discussed. • Optimized method for first-order hyperpolarizability and loading parameters of chromophore were discussed. • Method for improving stability of organic NLO materials was included. [ABSTRACT FROM AUTHOR]

In this study, principally novel lanthanide organic complexes Eu (TTA) 2 Phen (β-T) (LCA-D)containing Eu3+ ions, thenoyltrifluoroacetone (TTA), 1,10-phenanthroline (Phen), and β-thujaplicin (β-T) have been fabricated. Their fluorescence features were compared with those of Eu (TTA) 3 Phen (LCA-C) complexes, which are well-known light-emitting materials. The molecular and crystalline structures of complexes LCA-C and LCA-D were explored using nuclear magnetic resonance spectroscopy (1HNMR), Fourier transform infrared spectroscopy (FTIR), and X-ray powder diffraction (XRD). The optical properties of these complexes were also explored using ultraviolet–visible spectroscopy (UV–Vis), fluorescence spectra, and absolute photoluminescence quantum yield (PLQY). The obtained results showed that LCA-D possessed an intense absorption peak at wavelength about 239 nm and a weak absorption peak within a spectral range 250–375 nm with respect to LCA-C. LCA-D possesses a sharp red emission at λ = 615 nm upon excitation at λ = 348 nm, which was assigned to the electronic intra-center transition of 5D 0 -7F 2 of Eu3+ ions. After the addition of β-T, the intensity of emission peak at λ = 700 nm has been enhanced for LCA-D. The magnitude of QY for LCA-D was equal to about 23.91%, which was at least 11.4% higher than that of LCA-C. The thermal features tested for TG-DTG-DSC also indicated that LCA-D exhibited a promising temperature stability at ambient temperature up to 280 °C, which was suitable for agricultural film processing. Image 1 • UV spectra of Eu (TTA) 2 Phen-(β-T) have been explored. • Ligands were coordinated successfully to the central Eu3+ ion through N and O atom of the ligands. • Eu (TTA) 3 Phen (LCA-C), possess less intensive absorption than Eu (TTA) 2 Phen-(β-T) (LCA-D). • LCA-D has characteristic emission 580, 593, 615, 653, 700 nm when excited at 348 nm. • LCA-D possesses higher light conversion efficiency with respect to LCA-C. [ABSTRACT FROM AUTHOR]

Using biodegradable films as a substitute for conventional polyolefin films has emerged as a crucial technology to combat agricultural white pollution. To address the shortcomings in the tensile strength, water vapor barrier properties, and degradation period of PBAT-based biodegradable films, this investigation aimed to create a composite film that could improve the diverse properties of PBAT films. To achieve this, a PBAT/PLA-PPC-PTLA ternary blend system was introduced in the study. The system effectively fused PBAT with PLA and PPC, as evidenced by electron microscopy tests showing no apparent defects on the surface and cross-section of the blended film. The developed ternary blend system resulted in a 58.62% improvement in tensile strength, a 70.33% enhancement in water vapor barrier properties, and a 30-day extension of the functional period compared to pure PBAT biodegradable films. Field experiments on corn crops demonstrated that the modified biodegradable film is more suitable for agricultural production, as it improved thermal insulation and moisture retention, leading to a 5.45% increase in corn yield, approaching the yield of traditional polyolefin films. [ABSTRACT FROM AUTHOR]

[Display omitted] Solar-driven electrochemical NO 3 – reduction reaction (NO 3 -RR) is a clean and sustainable strategy that can convert pollutant NO 3 – in wastewater to value-added NH 3. In recent years, cobalt oxides-based catalysts have shown their intrinsic catalytic properties toward NO 3 -RR but still have room for improvement through catalyst design. Coupling metal oxides with noble metal has been demonstrated to improve electrochemical catalytic efficiency. Here, we use Au species to tune the surface structure of Co 3 O 4 and improve the efficiency of NO 3 -RR to NH 3. The obtained Au nanocrystals-Co 3 O 4 catalyst exhibited an onset potential of 0.54 V vs RHE, NH 3 yield rate of 27.86 µg/h·cm2, and Faradaic efficiency (FE) of 83.1% at 0.437 V vs RHE in an H-cell, which is much higher than Au small species (Au clusters or single atoms)-Co 3 O 4 (15.12 µg/h·cm2) and pure Co 3 O 4 (11.38 µg/h·cm2), respectively. Combined experiments with theory calculations, we attributed the enhanced performance of Au nanocrystals-Co 3 O 4 to the reduced energy barrier of *NO hydrogenation to the *NHO and suppression of HER, which originated from the charge transfer from Au to Co 3 O 4. Using an amorphous silicon triple-junction (a-Si TJ) as the solar cell and an anion exchange membrane electrolyzer (AME), an unassisted solar-driven NO 3 -RR to NH 3 prototype was realized with a yield rate of 4.65 mg/h and FE of 92.1%. [ABSTRACT FROM AUTHOR]

Anthocyanins (ANs) have strong antioxidant activities and can inhibit chronic diseases, but the instability of ANs limits their applications. The conservation of preheating whey protein concentrate (WPC) on the stability of purple sweet potato ANs was investigated. The retention of ANs in WPC-ANs was 85.88% after storage at 25 °C for 5 h. WPC-ANs had higher retention of ANs in heating treatment. The retention rates of ANs in WPC-ANs exposed to light and UV lamps for 6 h were 78.72% and 85.76%, respectively. When the concentration of H2O2 was 0.50%, the retention rate of ANs in the complexes was 62.04%. WPC-ANs' stability and antioxidant activity were improved in simulated digestive juice. The WPC-ANs connection was static quenching, and the binding force between them was a hydrophobic interaction at one binding site, according to the fluorescence quenching spectroscopy. UV-visible absorption spectroscopy and Fourier transform infrared spectroscopy (FTIR) analysis further indicated that the secondary structure and microenvironment of amino acid residues in WPC can be impacted by the preheating temperature and preheating times of WPC. In conclusion, preheating WPC can successfully preserve the stability of purple sweet potato ANs by binding to them through a non-covalent interaction. [ABSTRACT FROM AUTHOR]

To optimize the bamboo heat treatment process, the corresponding evolution rules under various heat treatment conditions must be determined. When the heat treatment time and temperature remained constant, the effects of different heat treatment pressures on the equilibrium moisture content, dimensional stability, mechanical properties, and chemical composition of bamboo were systematically investigated. In this experiment, bamboo without heat treatment was used as the control group. The experimental findings demonstrate the following: (1) The equilibrium moisture content of heat-treated bamboo gradually decreases with increasing treatment pressure. When the heat treatment pressure was set at 0.1, 0.15, 0.2, and 0.25 MPa, the bamboo's equilibrium water content decreased to 12.1%, 11.7%, 9.9%, and 8.6%, respectively, while that of the control group was 13.8%. (2) The dimensional stability of bamboo was enhanced with increasing heat treatment pressure. At pressures of 0.1, 0.15, 0.2, and 0.25 MPa, the radial air-dry shrinkage rates of the heat-treated bamboo decreased to 3.4%, 3.4%, 2.6%, and 2.3%, respectively, while the tangential air-dry shrinkage rates reduced to 5.6%, 5.1%, 3.3%, and 3.0%. In comparison, the radial and tangential air-dry shrinkage rates of the control group were measured as 3.6% and 5.8%, respectively. Similarly, the radial and tangential full-dry shrinkage of bamboo exhibited a similar trend. (3) With the increase in heat treatment pressure, the bending strength and longitudinal compressive strength of bamboo exhibited an initial rise followed by a decline. When it was at heat treatment pressures of 0.1, 0.15, 0.2, and 0.25 MPa, the corresponding bending strengths of the heat-treated bamboo were measured as 41.2, 26.7, 22.4, and 20.4 MPa, respectively; while the longitudinal compressive strengths were recorded as 42.6, 38.1, 29.1, and 25.3 MPa. In comparison, the bending and longitudinal compressive strengths of the control group were measured as 39.8 and 38.5 MPa, respectively. It is evident that the optimal heat treatment pressure for bamboo is 0.1 MPa, resulting in a significant increase of 3.5% and 10.6% in bending strength and longitudinal compressive strength, respectively, compared to the control group. (4) Based on the FTIR and XRD patterns of bamboo samples, a range of physical and chemical transformations were observed during the heat treatment process, including cellulose adsorb water evaporation, hemicellulose and cellulose degradation, as well as acetyl group hydrolysis on the molecular chain of hemicellulose. These changes collectively impacted the physical and mechanical properties of bamboo. [ABSTRACT FROM AUTHOR]

Novel nonlinear optical (NLO) chromophore based on 6-(pyrrolidin-1-yl)-1H-indole as the electron donor group was designed and synthesized. The molecular structure of this chromophore was characterized by 1 H NMR spectra, 13 C NMR spectra, and MS spectra. The delocalized energy level was estimated by UV–Vis. spectra. The thermal property was studied by thermogravimetric analysis (TGA). The poled films containing chromophores ZML-1 with a loading density of 10 wt% in amorphous polycarbonate (APC) afford an average electro-optic (EO) coefficient ( r 33 ) of 19 pm/V at 1310 nm. Compared to the reported aniline-based chromophore ( r 33 = 12 pm/V) analogues, chromophore ZML-1 exhibits enhanced electro-optical activity. [ABSTRACT FROM AUTHOR]

The composition/content of aroma compounds in tobacco leaves in the different producing areas varies too much, and it is very meaningful to develop advanced analysis techniques to investigate the composition/content-producing area correlation. Here, gas chromatography-ion mobility spectroscopy (GC-IMS) was used to analyze the composition/content of aroma compounds in tobacco samples from eight different producing areas. With this technique, ion mobility spectrum, differential ion mobility spectrum, and fingerprint spectrum were constructed for two-dimensional analysis. Then, the principal component analysis (PCA) and similarity analysis were performed for the eight tobacco samples. The results showed that the GC-IMS can detect 197 volatile aroma compounds in tobacco leaves and 75 of them are well identified. The fingerprint spectrum directly showed the difference in the composition/content of volatile aroma compounds in tobacco leaves from different producing areas. PCA and similarity analysis can clearly distinguish tobacco samples from different producing areas. This work demonstrated that the application of GC-IMS in analyzing the composition/content of aroma compounds in tobacco leaves is efficient. GC-IMS is a very powerful tool to give a direct and visual comparison of the composition/content of aroma compounds in tobacco leaves from different producing areas. The relationship between the composition/content of aroma compounds and producing areas could be established by this advanced technology. This work offers the possibility of planting or grading tobacco with different taste and smell more precisely in the future. [ABSTRACT FROM AUTHOR]

Fixation nitrogen using renewable energy has attracted much attention recently. However, the performance is limited by the competing hydrogen evolution reaction (HER) and the difficulty in activating N2. Here, an attractive strategy was proposed to enhance the electrochemical nitrogen reduction reaction (NRR) activity by introducing Pd into the HKUST‐1 framework. After thermal treatment, the obtained Pd/HKUST‐1 (250 °C) catalyst exhibited an ammonia production rate of 42.0 mg/gcat ⋅ h at −0.4 V vs. RHE with Faradaic efficiency of 4.6 %. The ammonia production reached as high as 415 mg/gcat in a 10‐hours stability test. With the assistance of density functional theory (DFT) calculations, the incorporated Pd was revealed to have the unique property to react with adsorbed H (Had) atom from HER and form α‐PdH species. Compared with other metals such as Ag, Au, and Pt, the in situ formed α‐PdH species could reduce the energy barrier of the rate‐limiting *N2H step, resulting in an enhanced NRR activity. [ABSTRACT FROM AUTHOR]

Polycaprolactone (PCL) is one of the promising linear aliphatic polyesters which can be used as mulching film. Although it has suitable glass transition temperature and good biodegradability, further practical applications are restricted by the limited temperature-increasing and moisturizing properties. The rational design of the PCL structure is a good strategy to enhance the related properties. In this study, thermally-induced phase separation (TIPS) was introduced to fabricate a PCL nanoporous thin film. The introduction of a nanoporous structure on the PCL surface (np-PCL) exhibited enhanced temperature-increasing and moisturizing properties when used as mulch film. In detail, the average soil temperature of np-PCL was increased to 17.81 °C, when compared with common PCL of 17.42 °C and PBAT of 17.50 °C, and approaches to PE of 18.02 °C. In terms of water vapor transmission rate, the value for np-PCL is 637 gm−2day−1, which was much less than the common PCL of 786 and PBAT of 890 gm−2day−1. As a result, the weed biomass under the np-PCL was suppressed to be 0.35 kg m−2, almost half of the common PCL and PBAT. In addition, the np-PCL shows good thermal stability with an onset decomposition temperature of 295 °C. The degradation mechanism and rate of the np-PCL in different pH environments were also studied to explore the influence of nanoporous structure. This work highlights the importance of the nanoporous structure in PCL to enhance the temperature-increasing and moisturizing properties of PCL-based biodegradable mulching film. [ABSTRACT FROM AUTHOR]

This study aimed to develop an effective technique for extracting total anthocyanins from purple sweet potato (Mianzishu 9) (PSP9) by ultrasound-assisted compound enzymatic extraction (UAEE). Single-factor experiments, Plackett-Burman experimental design, and response surface methodology were utilized for optimizing extraction conditions, and the antioxidant activities were evaluated. Anthocyanins were also measured using an ultra-performance liquid chromatograph linked to a mass spectrometer (UPLC-MS). The maximum yield of total anthocyanins was 2.27 mg/g under the following conditions: the ethanol concentration was 78%, the material-to-liquid ratio was 1:15 g/mL, the enzyme ratio (cellulase: pectinase: papain) was 2:2:1 and its hydrolysis was at 41 °C, pH = 4.5, 1.5 h, the ultrasonication was at 48 °C and conducted twice for 20 min each time. In addition to higher yield, anthocyanins extracted from purple sweet potato by UAEE showed great ability to scavenge DPPH (IC50 of 0.089 μg/mL) and hydroxyl radicals (IC50 of 100.229 μg/mL). Five anthocyanins were found in the purple sweet potato extract from UAEE. Taken together, the ultrasound-assisted compound enzymatic method can rapidly and effectively extract anthocyanins with greater antioxidant capacity from purple sweet potato. [ABSTRACT FROM AUTHOR]

Abstract: A novel nunchaku-like organic second order nonlinear optical chromophore containing a D–π–A backbone and a rigid biphenylene unit was prepared. The UV–vis absorption spectra studies demonstrated that the large rigid structure could suppress dipole–dipole interactions effectively. The electro-optic coefficient of a poled film containing 20% wt of the new dye doped in amorphous polycarbonate afforded a value of 39 pm/V at 1310 nm. Compared with results obtained from a similar D–π–A chromophore without the rigid isolated group, the new dye gave better performance. Moreover, the electro-optic film prepared with the new dye gave greater temporal stability, compared to a similar D–π–A doped poled film that was reported previously. These results indicated that the introduction of a biphenylene group could effectively reduce the intermolecular electrostatic interactions and aid the alignment of the chromophores. [Copyright &y& Elsevier]

Although the relationship between workplace fun and employee performance is well-documented, research on the link between workplace fun and voice behavior is still in a nascent stage. Integrating workplace fun, leader–member exchange (LMX), and voice behavior theories, in the current research we examined LMX as a mediator of the link between workplace fun and voice behavior. We conducted a cross-sectional survey with a sample of 307 subordinates and 82 supervisors employed by eight Chinese companies, and used structural equation modeling to analyze the data. Results show that workplace fun was related both directly and indirectly (via LMX) to employees' voice behavior. Our findings offer insight into the mechanistic processes through which workplace fun affects employees' voice behavior, and suggest that to promote employees' voice behavior, a fun work environment and high-quality LMX relationship should be established in organizations. [ABSTRACT FROM AUTHOR]

Clustering, a traditional machine learning method, plays a significant role in data analysis. Most clustering algorithms depend on a predetermined exact number of clusters, whereas, in practice, clusters are usually unpredictable. Although the Elbow method is one of the most commonly used methods to discriminate the optimal cluster number, the discriminant of the number of clusters depends on the manual identification of the elbow points on the visualization curve. Thus, experienced analysts cannot clearly identify the elbow point from the plotted curve when the plotted curve is fairly smooth. To solve this problem, a new elbow point discriminant method is proposed to yield a statistical metric that estimates an optimal cluster number when clustering on a dataset. First, the average degree of distortion obtained by the Elbow method is normalized to the range of 0 to 10. Second, the normalized results are used to calculate the cosine of intersection angles between elbow points. Third, this calculated cosine of intersection angles and the arccosine theorem are used to compute the intersection angles between elbow points. Finally, the index of the above-computed minimal intersection angles between elbow points is used as the estimated potential optimal cluster number. The experimental results based on simulated datasets and a well-known public dataset (Iris Dataset) demonstrated that the estimated optimal cluster number obtained by our newly proposed method is better than the widely used Silhouette method. [ABSTRACT FROM AUTHOR]

In-memory big data computing, widely used in hot areas such as deep learning and artificial intelligence, can meet the demands of ultra-low latency service and real-time data analysis. However, existing in-memory computing frameworks usually use memory in an aggressive way. Memory space is quickly exhausted and leads to great performance degradation or even task failure. On the other hand, the increasing volumes of raw data and intermediate data introduce huge memory demands, which further deteriorate the short of memory. To release the pressure on memory, those in-memory frameworks provide various storage schemes options for caching data, which determines where and how data is cached. But their storage scheme selection mechanisms are simple and insufficient, always manually set by users. Besides, those coarse-grained data storage mechanisms cannot satisfy memory access patterns of each computing unit which works on only part of the data. In this paper, we proposed a novel task-aware fine-grained storage scheme auto-selection mechanism. It automatically determines the storage scheme for caching each data block, which is the smallest unit during computing. The caching decision is made by considering the future tasks, real-time resource utilization, and storage costs, including block creation costs, I/O costs, and serialization costs under each storage scenario. The experiments show that our proposed mechanism, compared with the default storage setting, can offer great performance improvement, especially in memory-constrained circumstances it can be as much as 78%. [ABSTRACT FROM AUTHOR]

Novel nonlinear optical (NLO) chromophore using benzo[b]furan moiety and trifluoromethyl-substituted tricyanofuran as the electron donor and acceptor respectively was designed and prepared. The structure of the novel chromophore was determined by NMR spectra, and the photophysical properties were studied via UV-vis spectra. The thermal decomposition temperature (T d)value of the obtained NLO chromophore reached to 212 °C, which endow the chromophore with good thermal stability during the materials processing. The nonlinearity of the chromophore was evaluated through theoretical calculation and electro-optic (EO) activity test, and the highest EO coefficient (r 33) was determined to 28 pm/V at the loading density of 25 wt% in polymethyl methacrylate. • Novel benzofuran-based nonlinear optical chromophore was designed and synthesized. • The acceptor was unexpected linked to the β -position of furan in the chromophore. • The present chromophore exhibited go0d thermal stability (T d reached to 212 °C). • The maximum EO coefficient of the reported chromophore reached to 28 p.m./V. [ABSTRACT FROM AUTHOR]

Abstract Novel nonlinear optical chromophores JC-TCF and JC-FTCF using tetramethyljulolidine-based coumarin as the electron-donor and tricyanofuran derivatives as the electron acceptors were designed, synthesized and investigated. The obtained chromophores own good solubility in common solvents, and good compatibility with host polymers. The chromophores also have good thermal stability, and the decomposition temperature exceed 200 °C. The UV–vis spectra indicated that JC-TCF and JC-FTCF possess good intramolecular charge transfer ability. Density functional theory (DFT) was used to study the energy gap and first-order hyperpolarizability(β). After contact poling, the guest-host polymer films of polymethyl methacrylate containing 20% wt JC-TCF and 20% wt JC-FTCF exhibited the highest electro-optic coefficient (r 33) up to 40 p.m./V and 76 p.m./V respectively, and the results indicated the chromophores' microscopic β value could be effectively translated to macroscopic EO activity, and the tetramethyljulolidine-based coumarin could be an useful candidate in the development of NLO materials. Highlights • Julolidine-based coumarin was used as electron-donor in design of NLO materials. • The coumarin's good electron-donation ability obviously enhanced the NLO properties. • The obtained materials exhibited better EO activity compared to the FTC chromophores. • The maximum EO activity of reported NLO chromophores reached to 76 p.m./V. • Coumarin could be an useful candidate in the development of NLO materials. [ABSTRACT FROM AUTHOR]