Thermal and morphological properties of thermotropic liquid‐crystalline copolyesters containing poly(ethylene terephthalate), 4‐hydroxyphenylacetic acid and main‐chain rigid aromatic units

Thermotropic liquid‐crystalline polymers (TLCPs) have aroused considerable interest due to their attractive properties as high‐performance materials. Significant research attention has been devoted to investigating the relationship among monomer structures, syntheses and end‐use properties of TLCPs. The study reported here concerns the preparation, characterization and melt spinning of novel copolyesters containing two different flexible units together with two different aromatic units in the polymer chains. A range of copolyesters based on p‐hydroxybenzoic acid (p‐HBA), m‐hydroxybenzoic acid, p‐hydroxyphenylacetic acid and poly(ethylene terephthalate) were synthesized. The liquid crystallinity, thermal properties and degrees of crystallinity of these copolyesters were investigated using hot‐stage polarized light microscopy, differential scanning calorimetry, thermogravimetry and wide‐angle X‐ray diffraction. Copolyester fibres were characterized using scanning electron microscopy. The copolyesters were melt‐processable, thermally stable and could be processed above their melting temperatures without degradation. The degree of crystal structure was found to depend upon the content of p‐HBA. The fibres prepared showed that polymer chains had a well‐developed fibrillar structure. Novel TLCPs containing flexible units in the main chain were synthesized and characterized. Copolyesters containing p‐HBA units ranging from 55 to 70 mol% exhibited phase‐separated liquid‐crystalline morphology, appropriate melting temperatures and high thermal stability for melt processing. Copyright © 2010 Society of Chemical Industry     

A NONDESTRUCTIVE METHOD TO MEASURE RESIDUAL ADSORPTION CAPACITY OF CHARCOAL FILTERS

High surface area charcoal bed filters have been used for over a half a century to adsorb undesirable vapors from gas streams. One problem encountered when using these niter beds is that there is presently no simple, reliable, nondestructive method to measure their Residual Adsorption Capacity, RAC. This is particularly critical in situations where harmful vapors are being adsorbed.

An investigation has been underway to use pulses of weakly adsorbed gases such as ethane and/or methane to measure RAC. The hypothesis being that these weakly adsorbed gases will “count” unoccupied adsorption sites. In the present study, dimethyl methylphosphonate (DMMP) was used to “irreversibly” occupy available siles to various extents on different niters. The Reduced Retention Time. θ, (the ratio of the adjusted retention time to the space time) and the Resolution (R) between peaks of methane and ethane were found to correlate to RAC under dry and wet (humid) conditions.     

Fruit oil composition and characteristics of two spurge species of Turkish origin

Content and characteristics of the triglyceride fruit oils of two spurge (Euphorbia L.) subspecies, namelyE. glaerosa Pallas ex Bieb. (var.lasiocarpa Boiss.) andE. niciciana Borbas ex Novak, were investigated. For both taxa, oil content of the capsules enclosing the seeds ranged between 15.7 and 16.4% on dry basis, while the decapsulated seeds contained 33.0–34.0% oil, also on dry basis. The average saponification, iodine and acid values were 192, 190 and 6.0, respectively; linolenic acid was detected as the major constituent fatty acid. Consequently, these seed oils are characterized as typical drying oils.     

Gentamicin loaded β‐tricalcium phosphate/gelatin composite microspheres as biodegradable bone fillers

In this study, novel composite bone fillers with microspherical shape, biodegradable property, and antibacterial effect were designed and prepared. Various fillers with different β‐tricalcium phosphate (β‐TCP)/gelatin (G)/glutaraldeyde (GA) compositions were loaded with a model antibiotic, gentamicin. The effect of composition and preparation conditions on the release of gentamicin was investigated in in vitro conditions. Complete release were observed in 12 h for pure β‐TCP powder, and this period was extended up to 96 h as the gelatin content increased in the microspheres. Morphological and chemical structures of the microspheres, before and after the release studies, were investigated by scanning electron microscopy and Fourier transform infrared, respectively. Antibacterial activities were examined against Escherichia coli by using disc diffusion method and promising results were obtained. It is proposed that these novel β‐TCP/G/GA microspheres can be applied locally to prevent and/or eliminate infection that might occur around a defected region of hard tissue and supports the healing process. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Design of an intelligent decision support system for global outsourcing decisions in the apparel industry

Global outsourcing can be defined as assigning a specific business component to a global supplier. While global outsourcing enhances the capability of the enterprise, it also facilitates flexible enterprise structures. Many factors need to be considered simultaneously for global outsourcing decisions, and purchasing managers need a structured method of using these criteria in their decision-making. The scope of this study was to develop a fuzzy logic-based global outsourcing decision support system to evaluate the “make or buy” decision in the apparel industry. A fuzzy logic-based decision support system is constructed due to the similarity between fuzzy logic and human decision-making systems. The proposed approach decreases the dependency of the decision-making process on the decision-maker, establishing an effective system that can easily be applicable to most of the apparel industry.     

Finding the optimal tradeoff between area and delay in multiple constant multiplications

Over the years many efficient algorithms for the multiplierless design of multiple constant multiplications (MCMs) have been introduced. These algorithms primarily focus on finding the fewest number of addition/subtraction operations that generate the MCM. Although the complexity of an MCM design is decreased by reducing the number of operations, their solutions may not lead to an MCM design with optimal area at gate-level since they do not consider the implementation costs of the operations in hardware. This article introduces two approximate algorithms that aim to optimize the area of the MCM operation by taking into account the gate-level implementation of each addition and subtraction operation which realizes a constant multiplication. To find the optimal tradeoff between area and delay, the proposed algorithms are further extended to find an MCM design with optimal area under a delay constraint. Experimental results clearly indicate that the solutions of the proposed algorithms lead to significantly better MCM designs at gate-level when compared to those obtained by the solutions of algorithms designed for the optimization of the number of operations.     

An example of estimating rock mass deformation around an underground opening using numerical modeling

In rock engineering, rock strength is regarded as an important rock mass parameter and it is widely estimated using the uniaxial compressive strength (UCS) test. A UCS test in laboratory requires sampling and preparation of core samples, which necessitates time consuming and expensive studies. Furthermore, preparation of cores is almost impossible for a weak rock material taken from foliated, laminated or thinly bedded rock masses of low Rock Quality Designation (RQD) values (0–20%). In this case, determination of UCS by laboratory test may be impossible in compliance with ISRM or ASTM standards. To overcome this difficulty, indirect tests, such as Point Load Index (PLI), Schmidt Hammer (SH) Rebound Number tests are often employed to predict the UCS. However, indirect tests are likely to yield UCS values with large standard deviations depending on the geological origin of the rock mass.The Block Punch Index (BPI) has recently been developed to overcome the drawbacks of UCS and indirect tests and to minimize the errors arisen from the structural deficiencies and large standard deviations. In this study, determination of rock mass behavior in laminated–foliated Bornova Melange (yellowish-brown flysch and grayish-black flysch) and well-jointed Yamanlar Volcanics–Altindag Formation, where the second phase of the Izmir Metro tunnels was excavated is aimed. The BPI ratings were directly used in RMR calculations and indirectly used to estimate the UCS values of rock materials. Then, the obtained results were input into numerical models along with the rock mass strength (UCS_RM) and deformation modulus of rock mass (E_RM). The results obtained from the numerical models agreed with that obtained results from inner tunnel convergence and ground settlement measurements.     

Investigation of the relation between meteorological parameters,North Atlantic Oscillation and groundwater levels in Torbali Region,Turkey

Groundwater, the most reliable fresh water source, is used for drinking, domestic and agricultural purposes. Thereby, understanding its behaviour is important for the sustainability of groundwater sources. In this study, relations between the trends of climate parameters [recharge depending on precipitation, temperature and North Atlantic Oscillation Index (NAOI)] and groundwater levels trend were investigated for Torbali Region in Turkey. The human impact that is one of the deterministic components on the groundwater level has been removed from the groundwater level data sets. An increasing trend was observed in the early 1990s, and turning points were determined by using paired t‐test. The trends of the groundwater levels indicate that climate parameters affect groundwater levels in the similar manner. According to the results of the analyses, it is revealed that there is a similar linear variation that is strong and inverse between the trends of NAOI and meteorological indicator (temperature and recharge) and groundwater level.     

A cone‐beam computed tomography study of the anatomical relationships between mandibular teeth and the mandibular canal,with a review of the current literature

The purpose of this study was to evaluate age‐ and sex‐related changes in the anatomical relationships between the roots of the molars and premolars and the mandibular canal using cone‐beam computed tomography (CBCT) images. A total of 243 patients (116 males, 127 females) aged 16–83 years for whom previous CBCT scans were available were enrolled in this study. The patients were subcategorized by sex and age (Group I, <21 years; Group II, 21–40 years; and Group III, >40 years). The distances between the mandibular canal and the molars and premolars were measured. The mandibular canal was significantly closer to the root apices of the second and third molars than to the apices of other evaluated teeth (p < 0.05). All measurements were significantly higher in male than in female subjects (p < 0.05). Group I subjects exhibited significantly shorter distances between the mandibular canal and root apices of the first and second premolars, and the molars, than those of Group II and III subjects (p < 0.05). Direct contact relationships were found in 1.6%, 3.3%, 3.3%, 16%, and 32.2% of teeth (running from the first premolar to the third molar, respectively). Age and sex influenced the anatomical relationships between mandibular teeth and the mandibular canal, and these should be considered when planning endodontic and surgical procedures to avoid potential nerve injury.     

Optimal management of remanufacturing systems with server vacations

In this paper, we introduce a near optimal buffer allocation plan specifically developed for a remanufacturing system with finite buffers and server vacations. During server vacations, the server stops service for a random amount of time during which arrivals continue to occur. The term server vacation may be used for cases where the server leaves the primary queuing system to work on alternative duties for a random duration every time the server becomes idle (e.g., server could leave to work on additional tasks that he is responsible for or perform preventive maintenance on equipments). The remanufacturing system considered here consists of three modules, viz., the disassembly and testing modules for returned products and the remanufacturing module. In order to analyze the system, we propose an algorithm that uses an open queueing network, decomposition principle, and expansion methodology. The buffer allocation algorithm distributes the given number of available buffer slots among the remanufacturing system stations to optimize the system’s performance. The algorithm has been thoroughly tested using a variety of experimental conditions. The results show that the performance of the algorithm is consistent, robust, and produces excellent results.