NanoPaint: A Tool for Rapid and Dynamic Imaging of Membrane Structural Plasticity at the Nanoscale

Single‐particle tracking with quantum dots (QDs) constitutes a powerful tool to track the nanoscopic dynamics of individual cell membrane components unveiling their membrane diffusion characteristics. Here, the nano‐resolved population dynamics of QDs is exploited to reconstruct the topography and structural changes of the cell membrane surface with high temporal and spatial resolution. For this proof‐of‐concept study, bright, small, and stable biofunctional QD nanoconstructs are utilized recognizing the endogenous neuronal cannabinoid receptor 1, a highly expressed and fast‐diffusing membrane protein, together with a commercial point‐localization microscope. Rapid QD diffusion on the axonal plasma membrane of cultured hippocampal neurons allows precise reconstruction of the membrane surface in less than 1 min with a spatial resolution of tens of nanometers. Access of the QD nanoconstructs to the synaptic cleft enables rapid 3D topological reconstruction of the entire presynaptic component. Successful reconstruction of membrane nano‐topology and deformation at the second time‐scale is also demonstrated for HEK293 cell filopodia and axons. Named “nanoPaint,” this super‐resolution imaging technique amenable to any endogenous transmembrane target represents a versatile platform to rapidly and accurately reconstruct the cell membrane nano‐topography, thereby enabling the study of the rapid dynamic phenomena involved in neuronal membrane plasticity.     

Multinationality and Performance Literature: A Critical Review and Future Research Agenda

The literature on the relationship between the degree of multinationality (M) and performance (P) in the context of multinational enterprises (MNEs) has attracted a large volume of research in the past 50 years. Yet, the theoretical foundations and the empirical conclusions concerning the nature of M–P relationship vary greatly, thus call for a critical review and assessment. We examine 135 articles in 39 leading scholarly journals and classic books published during the period 1960–2015. We use an inductive approach and a qualitative content analysis methodology for our comprehensive and critical review of the literature. We incorporate international business, finance, and accounting perspectives in our analysis. We review the conceptualization and measurement of M, P, the findings on M–P relationships, methodologies, and geographic focus. We identify six key inconsistencies in the existing research, which cause ambiguity in the relevant findings. We make eight recommendations for future research to address these inconsistencies. Thus, our study contributes to the central debate in this research field.     

Influence of thermoviscoelastic properties and loading conditions on the recovery performance of shape memory polymers

This work investigated the influence of material properties and loading conditions on the recovery performance of amorphous shape memory polymers using a recently developed thermoviscoelastic model. The model incorporated the time-dependent mechanisms of stress and structural relaxation and viscoplastic flow to describe the glass transition of the material from a soft viscoelastic rubber to a hard viscoplastic glass. The model captured many important features of the unconstrained strain recovery response and of the stress hysteresis observed in the constrained recovery response. A parameter study was developed that varied the model and loading parameters one-by-one to compare their effects on the start and end temperatures and recovery rate of the unconstrained recovery response and on the stress hysteresis of the constrained recovery response. The loading parameters included the cooling rate, the annealing time, and the high and low temperatures of the programming stage and the heating rate of the recovery stage. The results confirmed experimental observations that viscoelasticity is the underlying mechanism of the unconstrained recovery response. In contrast, the constrained recovery response was influenced by the interaction of many different mechanisms, including thermal expansion and structural and stress relaxation. For the loading parameters, the cooling rate of the programming stage and the heating rate of the recovery stage had the largest influence on both the constrained and unconstrained recovery response.     

Fresnel-based beamforming for low-cost portable ultrasound

In this paper, we propose a modified electronic Fresnel-based beamforming method for low-cost portable ultrasound systems. This method uses a unique combination of analog and digital beamforming methods. Two versions of Fresnel beamforming are presented in this paper: 4-phase (4 different time delays or phase shifts) and 8-phase (8 different time delays or phase shifts). The advantage of this method is that a system with 4 to 8 transmit channels and 2 receive channels with a network of switches can be used to focus an array with 64 to 128 elements. The simulation and experimental results show that Fresnel beamforming image quality is comparable to traditional delay-and-sum (DAS) beamforming in terms of spatial resolution and contrast-to-noise ratio (CNR) under certain system parameters. With an f-number of 2 and 50% signal bandwidth, the experimental lateral beamwidths are 0.54, 0.67, and 0.66 mm and the axial pulse lengths are 0.50, 0.51, and 0.50 mm for DAS, 8-phase, and 4-phase Fresnel beamforming, respectively. The experimental CNRs are 4.66, 4.42, and 3.98, respectively. These experimental results are in good agreement with simulation results.     

Optimization of sodium sulfide treatment of rice straw to increase the enzymatic hydrolysis in bioethanol production

The efficiency of sodium sulfide-assisted alkaline pulping for cellulose preparation from Oryza sativa L. rice straw in Vietnam for enzymatic saccharification was investigated. The response surface methodology was used for the determination of optimal technological parameters of alkaline pulping such as active alkali dosage, temperature and time. The optimal technological parameters were established to be active alkali dosage of 7%, treatment temperature of 100 °C and treatment time of 120 min. At these regimes, a maximal sugar yield of 51.8% (over dry rice straw) was obtained. It meant that the saccharification efficiency up to 97.1% could be achieved by using sodium sulfide-assisted alkaline pretreatment method. Addition of sodium sulfide into alkaline pretreatment resulted in higher sugar yield, higher level of depolymerization of lignin and less loss of cellulose. Moreover, liquid hydrolyzate after enzymatic hydrolysis was analyzed by HPLC to determine the compositions of sugar mixture. The fiber morphology in pretreated biomass solid was also revealed by SEM.     

Synthesis,characterization and photoactivity of bi-crystalline mesoporous TiO2

Mesoporous titania (meso-TiO₂) has received extensive attention owing to its versatile potential applications. This paper reports a low-temperature templating approach for the fabrication of meso-TiO₂ using the peroxo titanic acid (PTA) sol as precursor and Pluronic P123 as nonionic template. The TGA, XRD, N₂ sorption, FE-SEM and HRTEM were used to characterize the obtained samples. The results showed that meso-TiO₂ with high surface area up to 163 m²·g^–1 and large pore volume of 0.65 cm³·g^–1 can be obtained. The mesopore sizes can be varied between 13 and 20 nm via this synthesis approach. The amount of P123 and the calcination conditions were found to have great influence on the mesoporous and crystalline structures of meso-TiO₂. The photocatalytic activity testing clearly shows that the high surface area and bi-crystallinity phases of meso-TiO₂ play important roles in enhancing photocatalytic properties of meso-TiO₂ in photo-decomposing Rhodamine B in water.     

Novel self-assembled mesalamine–sucralfate complexes: preparation,characterization, and formulation aspects

Two well-known active agents, mesalamine (MES) and sucralfate (SUC), were investigated for possible utilization as fixed-dose combination product. The anti-inflammatory action of MES in association with bioadhesiveness and mucosal healing properties of SUC were considered promising for the development of a new compound containing both molecules, aimed as an improved treatment of ulcerative colitis. The present study investigates the capacity of the two active agents to interact and generate a new and stable entity via self-assembling. Spray-drying was used to co-process the two active principles from an aqueous mixture where the ratio MES:SUC was in the range 25:75, 50:50, and 75:25. The structural data (X-Ray, FTIR, SEM, DSC, and ¹H NMR) have shown that MES and SUC are interacting leading to complexes with properties differing from those of each separate active agent and from their physical blends. ¹H NMR results indicated that complexation occurred when the aqueous suspensions of drugs were mixed, prior to spray-drying. Drug–drug self-assembling was the driving mechanism in the formation of the new entity. Based on the structural data, a hypothetical structure of the complex was proposed. Co-processing of MES and SUC represents a simple and useful procedure to prepare new self-assembled compounds by valorizing the ionic interactions between the two entities. Preliminary studies with oral solid dosage forms based on MES–SUC complexes tested in vitro have shown a controlled MES release, opening the perspective of a new colon-targeted delivery system and a novel class of compounds with therapeutic application in inflammatory bowel diseases.