Structured Estolides: Control of Length and Sequence

Using ester-forming reactions such as carbodiimide coupling and a modified Yamaguchi symmetrical anhydride method, a variety of estolides based on 17-hydroxy oleic and 17-hydroxy stearic acid have been prepared. These hydroxy fatty acids are produced in good yields from hydrolysis of sophorolipids, which are in turn derived from fermentation of fats and oils. Since the estolides are formed one unit, or ester bond, at a time, their length and sequence can be precisely controlled. The key to this control is the use of protecting groups at either the carboxylic or hydroxy end of the starting hydroxy fatty acids. Two mono-protected dimers, for example, when combined in a fragment-condensation approach, give a tetramer with no “contamination” from estolides of other lengths. This methodology opens the way to functionalized estolides, and several variants were prepared: hybrid estolides, containing non-fatty acid moieties such as amino acids; polymerizable estolides, containing a norbornene unit; and non-linear estolides that extend from a branched core such as glycerol or pentaerythritol. With the benzoyl chloride-mediated symmetrical anhydride method, yields for individual coupling steps ranged from 75 to 93%. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the US Department of Agriculture.     

Civil Liabilities for Unsafe Foods in Bangladesh and Australia: A Comparative Perspective on Consumer Protection

The statutory laws concerning food safety, which allow the consumers affected by unsafe foods to claim compensation for their loss or damage in Bangladesh, are flawed in several respects. These flaws are argued to have harmful impacts on consumer protection. The ineffective legislation in the absence of application of the common law principles of negligence has left the consumers virtually helpless in securing remedies for their injuries. This article endeavors to critically examine the ambiguities and shortcomings in the Consumer Rights Protection Act 2009 (Bangladesh) looking through the prisms of the Australian Consumer Law 2010 and relevant case law from major common law jurisdictions. It discovers a number of weaknesses in the legislation of Bangladesh and provides specific suggestions for strengthening the civil liability provisions from the perspective of consumer protection by preventing their contraventions and providing adequate compensation.     

2-Fatty Acrylic Acids: New Highly Derivatizable Lipophilic Platform Molecules

This paper reports the incorporation of an alpha-methylene unit into fatty acid skeletons. Since the new olefin is conjugated with the carboxylate, it is susceptible to 1,4-(Michael) additions. We have used multifunctional thiols and amines for additions at the methylene. The resulting products possess clusters of functionality grouped at one end of a hydrophobic tail. These structural patterns will be of use in the design of new types of bio-based surfactants and polymers. One particularly promising pattern of functionality that can be obtained through oxidation and reduction chemistry is a 2-fatty 1,2,3-propanetriol, or a lipophilized glycerol moiety.     

Synthesis and Characterization of Eu3+‐Doped Transparent Glass–ceramics Containing Nanocrystalline SrIINbIVO3

The glass–ceramics containing a rarely achievable nanocrystalline Sr^IINb^IVO₃ phase in the 53.75SiO₂–18.25K₂O–9Bi₂O₃–9SrO–9Nb₂O₅–0.5CeO₂–0.5Eu₂O₃ (mol%) glass system were prepared by the melt‐quench technique followed by a two‐stage controlled heat treatment. The unusual oxidation state of Nb in Sr^IINb^IVO₃ crystal is 4+ and upon heat treatment of the samples at lower temperature of 500°C for several hours, the glass composition and chemical environment around Nb ions played a key role for the formation of Sr^IINb^IVO₃ in the glass–ceramics. The microstructure of the glass–ceramics was studied using TEM and FESEM. The TEM images advocate 10–40 nm crystallite size of Sr^IINb^IVO₃. FTIR study confirms that all the samples consist of SiO₄, BiO₃, BiO₆, and NbO₆ structural units. The refractive index at different wavelengths was found to vary in the range 1.7105–1.7905 and increase with increase in heat‐treatment time. The luminescence spectra of Eu³⁺‐doped glass and glass–ceramics were recorded at 465 nm excitation wavelength and the luminescence intensity is found to be increased with heat‐treatment time due to increase in crystallinity. The high intensity ratio of ⁵D₀→⁷F₂ to ⁵D₀→⁷F₁ indicates that the Eu³⁺‐doped nanocrystalline Sr^IINb^IVO₃ glass–ceramics are promising candidate materials as red‐light source.     

Thermal,Structural, and Enhanced Photoluminescence Properties of Eu3+‐doped Transparent Willemite Glass–Ceramic Nanocomposites

The precursor glass in the ZnO–Al₂O₃–B₂O₃–SiO₂ (ZABS) system doped with Eu₂O₃ was prepared by the melt‐quench technique. The transparent willemite, Zn₂SiO₄ (ZS) glass–ceramic nanocomposites were derived from this precursor glass by a controlled crystallization process. The formation of willemite crystal phase, size, and morphology with increase in heat‐treatment time was examined by X‐ray diffraction (XRD) and field‐emission scanning electron microscopy (FESEM) techniques. The average calculated crystallite size obtained from XRD is found to be in the range 18–70 nm whereas the grain size observed in FESEM is 50–250 nm. The refractive index value is decreased with increase in heat‐treatment time which is caused by the partial replacement of ZnO₄ units of ZS nanocrystals by AlO₄ units due to generation of vacancies. Fourier transform infrared (FTIR) reflection spectroscopy was used to evaluate its structural evolution. Vickers hardness study indicates marked improvement of hardness in the resultant glass‐ceramics compared with its precursor glass. The photoluminescence spectra of Eu³⁺ ions exhibit emission transitions of ⁵D₀→⁷F_j (j = 0, 1, 2, 3, and 4) and its excitation spectra show an intense absorption band at 395 nm. These spectra reveal that the luminescence performance of the glass–ceramic nanocomposites is enhanced up to 17‐fold with the process of heat treatment. This enhancement is caused by partitioning of Eu³⁺ ions into glassy phase instead of into the willemite crystals with progress of heat treatment. Such luminescent glass–ceramic nanocomposites are expected to find potential applications in solid‐state red lasers, phosphors, and optical display systems.     

Reductionin Listeria monocytogenes,Salmonella enterica and Escherichia coli O157:H7 in vitro and on tomato by sophorolipid and sanitiser as affected by temperature and storage time

Increased consumption of produce by consumers has been attributed to perceived health benefits of postharvest produce. Pathogen control is crucial because periodic occurrences and contamination of tomato and leafy greens have exacerbated food safety risks for consumers. We investigated the effects of temperatures (5 and 25 °C), storage time (30 min and 24 h) for inactivation of Listeria monocytogenes, Salmonella enterica and Escherichia coli O157:H7 by sophorolipid (SL‐p) produced fermentatively using palmitic acid as a co‐substrate at different concentrations in vitro. Reduction in pathogenic bacteria on grape tomato by SL‐p, sanitiser (Lovit) and combinations of SL‐p and sanitiser was determined. Temperature and storage time significantly (P < 0.05) affected pathogen inactivations by SL‐p as pathogen reductions were greater at 25 °C and 24 h than at 5 °C and 30 min of storage. L. monocytogenes was the most sensitive to SL‐p treatment as reductions of 5 log relative to untreated controls were attained at 0.12% of SL‐p. Significant reductions in S. enterica (1.91–3.85 logs) and E. coli O157:H7 (0.87–4.09 logs) were recorded at 2–5% of SL‐p. Lower populations of Salmonella and E. coli O157:H7 were inactivated than L. monocytogenes. On grape tomato, pathogen populations inactivated increased at higher SL‐p levels at 25 °C. Sanitiser and sanitiser + SL‐p reduced bacterial populations on tomato by 5.29–5.76 logs and 0.71–3.3.66 logs, respectively. These results imply the interactions of temperature, storage time and SL‐p significantly (P < 0.05) affected pathogen strain reductions. The combination of SL‐p with sanitiser led to synergistic effect on E. coli O157:H7, but not L. monocytogenes and S. enterica.     

Error probability of fast frequency hopping spread spectrum withBFSK modulation in selective Rayleigh and selective Rician fadingchannels

The performance of noncoherent reception in fast frequency hopped spread-spectrum (FFH-SS) communication systems operating through noisy, fading multipath channels is investigated. Systems operating with binary frequency-shift keying (BFSK) modulation and noncoherent demodulation are examined under the assumption of very slow fading. These analyses demonstrate the frequency hopping benefits in selective channels. Expressions are derived for the bit error rate in the context of selective Rayleigh and selective Rician fading channels, as a function of channel and system parameters     

Surge characteristics of a twisted pair

We used the method of moments (MoM), which is a numerical electromagnetic field computation method, to study the surge characteristics of twisted pair single‐phase electric power lines. The results show that wires stranded with less than several turns per meter have almost the same surge characteristics as parallel lines, but the surge impedance decreases in tens of % when the number of strands increases. To verify the simulation results, we measured the surge characteristics of a model line of twisted pair experimentally, and there is good accordance between them. It is possible to simulate the surge in twisted pair covered with polymer dielectric insulators by MoM. Moreover, we studied the surge characteristics of twisted pair which is inserted into a metal tube. According to the results, the effect of the strand is smaller than that in free space without the metal pipe. There are two propagation modes in common mode: fast surge and slow surge. Few influences of the number of strands on the surge velocity occur in the fast propagation surge, but the increase of the surge impedance and the slowdown of the propagation speed are caused by twining in the slow propagation mode. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(3): 1–9, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20737     

Clickable Lipids: Azido and Alkynyl Fatty Acids and Triacylglycerols

Hydroxy fatty acids (FAs), which were isolated from glycolipids that can be prepared fermentatively from fats and oils, have been synthetically modified to contain azide and alkyne functional groups. These particular functional groups were chosen because they can participate in a copper-catalyzed reaction that combines them to form a 1,4-triazole, known as a “click” reaction, which has been widely used in a variety of fields but remains underutilized in FA chemistry. Depending on the starting hydroxy FA, these groups can be close to the carboxy unit (using 3-hydroxydecanoate) and hence the polar glycerol group, or distant from it (using 17-hydroxyoctadecanoate). These structural alternatives will impart different properties to the triacylglycerols that are subsequently prepared from the modified FA. Finally, the click reaction was used to conjugate triacylglycerols to each other and to other molecules such as a glycolipid or a protected amine.