Physical agglomeration behavior in preparation of cellulose‐N‐methyl morpholine N‐oxide hydrate solutions by simple mixing

The different melting temperatures of N‐methyl morpholine N‐oxide (NMMO) hydrates in the cellulose–NMMO hydrate solution may be explained by the rather different crystal structures of NMMO hydrates, which are determined by the amount of the hydrates. The preparative process of cellulose–NMMO hydrate solution may result in cellulose structural change from cellulose I to cellulose II, depending on the amount of the hydrate. Mixtures of cellulose and NMMO hydrate in a blender was changed from the granules to slurry with increasing mixing time at 60–70°C, which is below the melting point of the NMMO hydrate. In the case of 15 wt % cellulose–NMMO hydrate granules, which were made by mixing for 20 min, the melting points of various NMMO hydrates were obtained as 77.8°C (n = 0.83), 70.2°C (n = 0.97), and 69.7°C (n = 1.23), respectively, depending on the hydrate number. However, the melting points of cellulose–NMMO hydrate slurry and solution were shifted lower than those of cellulose granules, while the mixing time of slurry and solution are 25 and 35 min, respectively. These melting behaviors indicate instantaneous liquefaction of the NMMO hydrate and the diffusion of the NMMO hydrate into cellulose during mixing in a blender. When cellulose was completely dissolved in NMMO hydrate, the crystal structure of cellulose showed only cellulose II structure. In the cellulose–NMMO products of granules or slurry obtained by high‐speed mixing, which is a new preparation method, they still retained the original cellulose I structure. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1687–1697, 2004     

Stationary policies for lower bounds on the minimum average cost of discrete‐time nonlinear control systems

The paper deals with the control problem of discrete‐time nonlinear systems. The main contribution of this note is to present conditions that assure the existence of stationary policies that generate lower bounds for the minimal long‐run average cost. These lower bounds coincide with the optimal solution when a mild convergence assumption holds. To illustrate the results, the paper presents an application for the simultaneous state‐feedback control problem, and the derived strategy is used to design a real‐time simultaneous control for two direct current motor devices. The dynamics of these two devices are written in terms of a nonlinear algebraic matrix recurrence, which in turn represents a particular case for our general nonlinear approach. The optimal gain for the corresponding simultaneous state‐feedback problem is obtained, and such a gain was implemented in a laboratory testbed to control simultaneously the two direct current motors. Copyright © 2013 John Wiley & Sons, Ltd.     

Comparative Analysis of Single‐Cascade Five‐Zone and Two‐Zone SMB Systems for the Separation of a Ternary Amino Acid Mixture

A ternary separation usually requires the use of two simulated moving bed (SMB) units in series. Since an increase in the number of SMB units leads to a significant increase in capital and operational costs, the use of a single SMB unit is preferred if its structure can be modified to treat a ternary separation. Such a modified single SMB unit has been typified by a five‐zone SMB or a two‐zone SMB so far. The separation performances‐of a five‐zone SMB and a two‐zone SMB are compared in this paper by using the ternary amino acid mixture as a model system. A five‐zone SMB is designed with the safety margin method while a two‐zone SMB is optimized using genetic algorithm. A five‐zone SMB based on the maximum allowable safety margin, although it may not guarantee the global optimum solution, results in much better separation performance than a two‐zone SMB at its global optimum state.     

Preparation and characterization of maleic anhydride‐g‐polypropylene/diamine‐modified clay nanocomposites

Polypropylene (PP)/montmorillonite (MMT) nanocomposites were prepared by compounding maleic anhydride‐g‐polypropylene (MAPP) with MMT modified with α,ω‐diaminododecane. Structural characterization confirmed the formation of characteristic amide linkages and the intercalation of MAPP between the silicate layers. In particular, X‐ray diffraction patterns of the modified clay and MAPP/MMT composites showed 001 basal spacing enlargement as much as 1.49 nm. Thermogravimetric analysis revealed that the thermal decomposition of the composite took place at a slightly higher temperature than that of MAPP. The heat of fusion of the MAPP phase decreased, indicating that the crystallization of MAPP was suppressed by the clay layers. PP/MAPP/MMT composites showed a 20–35% higher tensile modulus and tensile strength compared to those corresponding to PP/MAPP. However, the elongation at break decreased drastically, even when the content of MMT was as low as 1.25–5 wt %. The relatively short chain length and loop structure of MAPP bound to the clay layers made the penetration of MAPP molecules into the PP homopolymer phase implausible and is thought to be responsible for the decreased elongation at break. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 307–311, 2005     

Polyunsaturated fatty acids in tissues of rats fed trielaidin and high or low levels of linolenic acid

Male and female weanling rats that were born to dams fed a diet low in linolenic acid received diets of 15% lipids by weight containing 45% elaidic acid (as trielaidin) and 8.5% or 0.1% linolenic acid for 10 weeks. Four other groups, in which palmitic or oleic acid replaced elaidic acid in the diet, served as controls. The fatty acid profiles of several lipid classes were determined in adipose tissue, adrenals, testes, heart and brain. Elaidic acid was incorporated into tissue lipids in varying degrees, depending on the organ and on the lipid class. Feeding elaidic acid induced no changes in the polyunsaturated fatty acid (PUFA) profiles of testes lipids but resulted in definite modifications of the PUFA patterns of heart phosphatidylcholine (PC) and phosphatidylethanolamine (PE). In linolenic acid-deprived rats, arachidonic acid was decreased in PC and linoleic acid was increased in both PC and PE; 22∶5n−6 was strongly depressed in both PC and PE. In linolenic acid-fed rats, 22∶6n−3 was decreased in PC and PE. These changes, on the whole, were more evident in females, and some also were observed in adrenal cholesteryl esters but only slightly in brain phospholipids. the apparent inhibition of the biosynthesis of PUFA induced by dietary elaidic acid appeared to be complex and of greater intensity in the n−6 fatty acid series than in their n−3 homologues.     

Degradation of a textile azo dye by pulsed arc discharge to the surface of wastewater

The pulsed arc discharge to the surface of wastewater was applied to the degradation of a textile azo dye (Acid Red 27). A high-voltage electrode (discharging electrode) was vertically placed above the surface of the wastewater while the wastewater itself was grounded. The pulsed arc discharge occurred between the tip of the discharging electrode and the surface of the wastewater, producing various oxidative species. Oxygen was used as the working gas instead of air to prevent nitrogen oxides from forming. The effect of several parameters on the chromaticity and chemical oxygen demand (COD) removal was examined. The results obtained showed that the chromaticity of the wastewater was completely removed by this process and the COD also decreased significantly. It has been found that ozone formed in the gas phase mainly affects the removal of the dye. The contribution of other effects such as ultraviolet light emission and OH radical formation during the arc discharge to the degradation of the dye was found to be less than 15%. For the present reactor system, the optimum pH, pulse repetition rate and agitation speed were found to be 3.0, 110 Hz and 300 rpm, respectively.     

Faceless identification based on temporal strips

This paper first presents a novel approach for modelling facial features, Local Directional Texture (LDT), which exploits the unique directional information in image textures for the problem of face recognition. A variant of LDT with privacy-preserving temporal strips (TS) is then considered to achieve faceless recognition with a higher degree of privacy while maintaining high accuracy. The TS uses two strips of pixel blocks from the temporal planes, XT and YT, for face recognition. By removing the reliance on spatial context (i.e., XY plane) for this task, the proposed method withholds facial appearance information from public view, where only one-dimensional temporal information that varies across time are extracted for recognition. Thus, privacy is assured, yet without impeding the facial recognition task which is vital for many security applications such as street surveillance and perimeter access control. To validate the reliability of the proposed method, experiments were carried out using the Honda/UCSD, CK+, CAS(ME)² and CASME II databases. The proposed method achieved a recognition rate of 98.26% in the standard video-based face recognition database, Honda/UCSD. It also offers a 81.92% reduction in the dimension length required for storing the extracted features, in contrast to the conventional LBP-TOP.

     

Irregular Depth Tiles: Automatically Generated Data Used for Network-based Robotic Grasping in 2D Dense Clutter

Recent advances in deep learning have enabled robots to grasp objects even in complex environments. However, a large amount of data is required to train the deep-learning network, which leads to a high cost in acquiring the learning data owing to the use of an actual robot or simulator. This paper presents a new form of grasp data that can be generated automatically to minimize the data-collection cost. The depth image is converted into simplified grasp data called an irregular depth tile that can be used to estimate the optimal grasp pose. Additionally, we propose a new grasping algorithm that employs different methods according to the amount of free space in the bounding box of the target object. This algorithm exhibited a significantly higher success rate than the existing grasping methods in grasping experiments in complex environments.

     

Transmission electron microscopy study of extended defect evolution and amorphization in SiC under Si ion irradiation

The damage induced in 3C-SiC epilayers on a silicon wafer by 2.3-MeV Si ion irradiation for fluences of 10¹⁴, 10¹⁵, and 10¹⁶ cm⁻², was studied by conventional and high-resolution transmission electron microscopy (TEM/HRTEM). The evolution of extended defects and lattice disorder is followed in both the 3C-SiC film and Si substrate as a function of ion fluence, with reference to previous FTIR spectroscopy data. The likelihood of athermal unfaulting of native stacking faults by point defect migration to the native stacking faults is discussed in relation to damage recovery. Threshold energy densities and irradiation doses for dislocation loop formation and amorphous phase transformation are deduced from the damage depth profile by nuclear collisions. The role of electronic excitations on the damage recovery at high fluence is also addressed for both SiC and Si.     

Near infrared light-induced disassembly of polymeric micelles based on methylene blue conjugated polyethylene glycol

Light-sensitive drug delivery systems are considered ideal for applications in the biomedical fields for their ability to release the payload in an on-demand spatiotemporal controlled manner through the manipulation of the light source. Among the broad radiation spectrum, near infrared (NIR) light is considered advantageous compared to UV and visible light, due to its inherently lower photodamage to normal tissues and deeper penetration to lesion areas. In this study, we report a successful synthesis of a polymer capable of undergoing partial degradation upon irradiation with NIR light by conjugating 10-N-carbamoyl linkage methylene blue (MB) moiety, a NIR photocleavable ligand, with polyethylene glycol (PEG). Through effective coupling of MB, a hydrophobic moiety, to the hydrophilic PEG molecule, an amphiphilic polymer was synthesized, as demonstrated by a lowered surface tension (55 mN/m at 0.1% wt/vol). Subsequently, photo-induced reversal of surface activity associated with self-assembled structure disruption, was displayed by surface tension measurements, size distribution analysis, and burst release profile of paclitaxel (PTX) from polymeric micelles upon the exposure to NIR irradiation.