Solving distribution problems in content-based recommendation system with gaussian mixture model

Applied Intelligence - Recommendation systems play an important role in boosting purchasing consumption for many manufacturers by helping consumers find the most appropriate items. Furthermore,...     

In-Situ Investigation on Nanoscopic Biomechanics of Streptococcus mutans at Low pH Citric Acid Environments Using an AFM Fluid Cell

Streptococcus mutans (S. mutans) is widely regarded as the main cause of human dental caries via three main virulence factors: adhesion, acidogenicity, and aciduricity. Citric acid is one of the antibiotic agents that can inhibit the virulence capabilities of S. mutans. A full understanding of the acidic resistance mechanisms (ARMs) causing bacteria to thrive in citrate transport is still elusive. We propose atomic force microscopy (AFM) equipped with a fluid cell to study the S. mutans ARMs via surface nanomechanical properties at citric acid pH 3.3, 2.3, and 1.8. Among these treatments, at pH 1.8, the effect of the citric acid shock in cells is demonstrated through a significantly low number of high adhesion zones, and a noticeable reduction in adhesion forces. Consequently, this study paves the way to understand that S. mutans ARMs are associated with the variation of the number of adhesion zones on the cell surface, which is influenced by citrate and proton transport. The results are expected to be useful in developing antibiotics or drugs involving citric acid for dental plaque treatment.     

Cache-aided full-duplex: delivery time analysis and optimization

Edge caching has received much attention as a promising technique to overcome the stringent latency and data-hungry challenges in the future generation wireless networks. Meanwhile, full-duplex (FD) transmission can potentially double the spectral efficiency by allowing a node to receive and transmit at the same frequency band simultaneously. In this paper, we investigate the delivery time performance of a cache-aided FD system, in which an edge node, operates in FD mode, serves users via wireless channels and is equipped with a cache memory. Firstly, we derive a closed-form expression for the average delivery time by taking into account the uncertainties of both backhaul and access wireless channels. The derived analysis allows the examination of the impact of key parameters, e.g., cache size and transmit power. Secondly, a power optimization problem is formulated to minimize the average delivery time. To deal with the non-convexity of the formulated problem, we propose an iterative optimization algorithm based on the bisection method. Finally, numerical results are presented to demonstrate the effectiveness of the proposed algorithm. A significant delivery time reduction is achieved by the proposed optimization compared to the FD reference and half-duplex counterpart.

     

Influence of Cr3+ on yellowish-green UC emission and energy transfer of Er3+/Cr3+/Yb3+ tri-doped zinc silicate glasses

In this paper, we study the influence of Cr³⁺ on yellowish-green upconversion (UC) emission and the energy transfer (ET) of Er³⁺/Cr³⁺/Yb³⁺ tri-doped in SiO₂–ZnO–Na₂O–La₂O₃ (SZNL) zinc silicate glasses under excitation of the 980 nm laser diode (LD). The influence of Cr³⁺ on enhancing the red UC emission of Er³⁺/Cr³⁺/Yb³⁺ tri-doped in SiO₂–ZnO–Na₂O–La₂O₃ zinc silicate glasses under the excitation of 980nm LD was also investigated. The ET processes between Yb³⁺, Cr^3+, and Er³⁺, together with the combination of Yb³⁺-Cr³⁺-Er³⁺, which led to the green UC emission intensity of Er³⁺/Cr³⁺/Yb³⁺ tri-doped in SiO₂–ZnO–Na₂O–La₂O₃ zinc silicate glasses bands centered at ~546 nm have been significantly enhanced. By increasing the concentration of Cr³⁺ from 0 up to 5 mol.%, we can locate the Commission Internationale de l'éclairage (CIE) 1931 (x; y) chromaticity coordinates for UC emissions of Er³⁺/Cr³⁺/Yb³⁺ tri-doped in the central position of the yellowish-green color region of CIE 1931 chromaticity diagram. Besides, the ET processes between the Yb³⁺, Cr³⁺, and Er³⁺ are also proposed and discussed.     

Phototemtide A,a Cyclic Lipopeptide Heterologously Expressed from Photorhabdus temperata Meg1, Shows Selective Antiprotozoal Activity

A new cyclic lipopeptide, phototemtide A ( 1 ), was isolated from Escherichia coli expressing the biosynthetic gene cluster pttABC from Photorhabdus temperata Meg1. The structure of 1 was elucidated by HR-ESI-MS and NMR experiments. The absolute configurations of amino acids and 3-hydroxyoctanoic acid in 1 were determined by using the advanced Marfey's method and comparison after total synthesis of 1 , respectively. Additionally, three new minor derivatives, phototemtides B–D ( 2 – 4 ), were identified by detailed HPLC–MS analysis. Phototemtide A ( 1 ) showed weak antiprotozoal activity against Plasmodium falciparum, with an IC₅₀ value of 9.8 μm . The biosynthesis of phototemtides A–D ( 1 – 4 ) was also proposed.     

Calculation of Building Settlement Induced by Deep Excavation Under Seismic Loading

Soil Mechanics and Foundation Engineering - The present article describes a procedure for predicting the settlement of structures surrounding deep excavations in Vietnam that takes the...     

Self-assembled poly(ethylene glycol) methyl ether-grafted gelatin nanogels for efficient delivery of curcumin in cancer treatment

Curcumin (CUR) is a natural active ingredient that attracted much attention for its chemotherapeutic activity against tumors without causing toxicity in healthy cells. However, it has certain limitations for being used in chemotherapy such as low aqueous solubility and hydrolytic instability in the physiological environment. In this study, self-assembled poly(ethylene glycol) methyl ether-grafted gelatin (Gel-mPEG) nanogels were fabricated as delivery systems to improve the applicability of CUR in cancer treatment. CUR-loaded Gel-mPEG nanogels exhibited desired size range, relatively colloidal stability, and provided enhanced CUR stability in aqueous solutions. Especially, they showed significant high CUR loading capacity and better anticancer activity than free CUR as compared to previously reported CUR-loaded nanogels according to the best of our knowledge. Moreover, the in vitro release of CUR from the nanogels was controlled and prolonged up to 96 h. These results demonstrated that Gel-mPEG nanogels are the promising modality for the efficient delivery of CUR in cancer treatment. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47544.     

Efficient and accurate measurement of very sharp crystallographic textures: A new measurement strategy

A new measurement strategy is introduced to determine very pronounced crystallographic textures of polycrystalline materials most accurately and efficiently. It features optimized adaptively refined successive X-ray pole figure measurements. To optimize both the total experimental time as well as the angular resolution, and thus the accuracy of pole figure measurements, traveling salesman problems on the hemisphere of poles have to be resolved. The corresponding algorithm is encoded and implemented as part of the software controlling the texture goniometer. The procedure was applied to pole figure measurements of a NiW alloy with extremely sharp Cube texture. The results are presented and compared to conventional measurement strategies.     

Spark Parameter Monitoring Feedback System for Preparation of Nanosilver Colloid in EDM

This study developed a system monitoring the electric discharge machine's (EDM) discharge energy and success rate to replace conventional oscilloscope observation. By using logic circuit, the signals are transmitted to the PC monitoring platform in order to display the discharge success times, discharge success rate, and electrode's consumption energy. The advantage of the proposed system is the capability to observe real-time discharges and record the experimental conditions, as well as optimize the discharge parameter settings. The experimental results suggest that, in the preparation of nanosilver colloid, the cost-performance of T_on–T_off at 10–100 µs is the optimal setting. The monitoring system also can take advantage of the discharge success rate to control the energy consumption of the electrode to obtain the standardization of products. The results suggest that, while discharge success rate, electrode's weight loss and wavelength of the absorption peak are considerably accurate, but concentration accuracy is relatively poor. The discharge success rate monitoring system is an innovative method that can help to realize electric discharge processing, optimize product quality, and it may be a powerful processing tool in the future.