Search results

(b) Linear Homopolymers Linear poly(vinyl acetate) and polybutadiene samples were studied by Park and Graessley using GPC combined with capillary viscometry which provided both the distribution of hydrodynamic volumes and intrinsic viscosities of the samples. Their equipment comprised a Waters Associates Chromatograph (model 200) fitted with five Styragel columns of porosities 106, 105, 1.5 × 104, 104 and 3 and 103 mm eluted with THF at room temperature at a flow rate of 1 cm3 min−1. Samples of 2 cm3 nominal volume were injected at a concentration of 0.25 g per 100 cm3 and detection was by a differential refractometer coupled to a digital curve translator so that readings were digitised and fed to a teletype machine at one minute intervals. From the refractometer, the sample passed via a syphon device into an all glass viscometer of the Ubbelohde type and the whole of this equipment was totally immersed in a water bath whose volume was sufficient to smooth out minor temperature variations in the equipment. The viscometer discharge was detected photoelectrically and the time taken determined by an electronic timer which gave a signal that was also recorded on the teletype.

The Commission appointed jointly by the World Health Organization and the Food and Agricultural Organization continues to plod its weary way towards the establishment of Codex standards for all foods, which it is hoped will eventually be adopted by all countries, to end the increasing chaos of present national standards. We have to go back to 1953, when the Sixth World Health Assembly showed signs of a stirring of international conscience at trends in food industry; and particularly expressed “the view that the increasing use of various chemical substances had … , created a new public health problem”. Joint WHO/FAO Conferences which followed initiated inter alia international consultations and the setting up of the Joint FAO/WHO Codex Alimentarius Commission.

This paper aims to provide details of the major optical gas sensing techniques and their applications.

Following an introduction, this paper first identifies the major gas sensing technologies and provides an overview of optical sensing techniques. The sources and impact of the gases most frequently sensed by optical methods are listed. Three non-absorption-based and nine absorption-based methods and their main applications are then described in detail. Brief concluding comments are drawn.

All manner of optical gas sensing techniques have been commercialised and while the majority are absorption-based, several other methods also play a significant role. Some optical gas sensors offer advanced capabilities such as remote monitoring, the creation of 2D and 3D distribution maps, detection of parts per trillion levels and even the visualisation of gases in real time. They play a vital role in protecting workers from hazardous gases, controlling and minimising air pollution and monitoring the atmospheric environment, as well as being used in the food, medical, process, power generation and other industries.

This paper provides a detailed insight into optical gas sensing techniques and their uses.

“It is generally accepted that the food industry must be scientifically based to cope with the problems, particularly of public health, which arise as new processes of growing, manufacturing, packaging and preserving food depart even further from traditional ways.”

Volatile flavor plays a main role in defining the fruit quality by consumers. Bruising leads often to dark spots on fruits and its amount could highly affect product quality. This paper aims to study the effect of bruising on the volatilome released by pears by using proton transfer reaction – mass spectrometry (PTR-MS).

Fingerprints of non-bruised and bruised pear samples were collected through PTR-MS for 28 days, and discriminant analysis was used to discriminate the fruit products. The CIELAB color changes were also measured during the entire ripening period.

Bruised pears released a higher intensity of volatile organic compounds (VOCs) compared to non-bruised pears (p_16days = 0.049, p_22days = 0.012, p_28days = 0.006). In particular, the release of m/z 45 and m/z 47 were significantly (p_m/z 45 = 0.076, p_m/z 47 = 0.095.) higher in bruised samples, suggesting that the bruising event accelerated the natural ripening process. CIELAB color coordinates were also recorded. The coordinate a* showed a linear increase during the whole 28 days because of the loss of the green component. The CIELAB ΔE* was higher in the bruised pears than the non-bruised pears (p = 0.022).

Bruising can affect food quality and taste. Bruise susceptibility has been largely studied on apples, tomatoes and peaches, but rarely on pears. Very little is known about the effect of bruising on the volatilome of pears. Moreover, bruising research usually involved the study of physical properties; on the contrary, PTR-MS, applied to bruising research, has never been used before. Besides the analysis of volatilome, the changes in color were also recorded for the whole 28 days of analysis. The proposed method could be applied for the monitoring of pears quality in the food industry.

The purpose of this paper is to investigate the process of rapid prototyping eddy current sensors using 3D printing technology. Making full use of the advantages of 3D printing, the authors study on a new method for fabrication of an eddy current sensor.

In this paper, the authors establish a 3D model using SolidWorks. And the eddy current sensor is printed by the fused deposition modeling method.

Measurement results show that the 3D printing eddy current sensor has a wider linear measurement range and better linearity than the traditional manufacturing sensor. Compared to traditional eddy current sensor fabrication method, this 3D printed sensor can be fabricated at a lower cost, and the fabrication process is more convenient and faster.

This demonstrated 3D printing process can be applied to the 3D printing of sensors of more sophisticated structures that are difficult to fabricate using conventional techniques.

In this work, the process of rapid prototyping eddy current sensors using 3D printing is presented. Sensors fabricated with the 3D printing possess lots of merits than traditional manufactures. 3D printed sensors can be customized according to the configuration of the overall system, thus reducing the demand of sensor's rigid mounting interfaces. The 3D printing also reduce design costs as well as shortens the development cycle. This allows for quick translation of a design from concept to a useful device.

Examines the fifteenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects. Subjects discussed include cotton fabric processing, asbestos substitutes, textile adjuncts to cardiovascular surgery, wet textile processes, hand evaluation, nanotechnology, thermoplastic composites, robotic ironing, protective clothing (agricultural and industrial), ecological aspects of fibre properties – to name but a few! There would appear to be no limit to the future potential for textile applications.

This study examines solvent extract conductivity (SEC) testing, e.g., Ionograph or Omega Meter testing, which measures ionic cleanliness of printed wiring boards (PWBs). SEC has been a quality control (QC) monitor to assure product electrical reliability. Typical SEC measurements occur after wave soldered products have been solvent‐cleaned. This study concerns SEC testing on new wave soldering processes that involve no solvent cleaning, i.e., inert gas soldering with ‘no clean’ fluxes. Results show ionic residues from ‘no clean’ fluxes may have other characteristics that make QC testing for ionic cleanliness inappropriate. However, SEC may be appropriate as a process control monitor after soldering with these fluxes. An Ionograph measured SEC response for the following chemicals: NaCl, NaF, NaBr, KCl, MgCl2, CaCl2, HCl, succinic acid, malic acid, glutaric acid, adipic acid and ethylene glycol. The list includes inorganic salts, strong electrolytes, which may arise from manufacturing or PWB materials. The list also includes weak organic acids (WOAs) common to ‘no clean’ fluxes. One non‐ionic hygroscopic chemical, ethylene glycol, was studied. Ionograph response was measured via (i) direct injection of aqueous solutions and (ii) immersion of PWBs with individual chemicals as surface deposits. All ionisable compounds, including all WOAs, produced substantial SEC response. Surface conductivity was measured at 35°C/90% relative humidity (RH) with controlled amounts of the above chemicals deposited on clean PWB test circuits. Surface loadings corresponded to the molar‐ionic equivalent of 2.0 ?g/cm2 NaCl. In addition, NaCl, adipic acid and polyethylene glycol (PEG 400) were examined as a function of concentration. Several ionisable chemicals including all WOAs produced no measurable effect, i.e., surface conductivities were indistinguishable on clean and deposited specimens. Surface conductivity increased for ionic contaminants with critical RH below ∼80% and for the non‐ionic hygroscopic glycol. SEC measurements and surface conductivities were compared. The latter is more directly related to electrical reliability. Although all ionic compounds including the WOAs showed a SEC response, not all enhanced surface conductivity. Achievement of critical RH appears to be the important factor. Adipic acid required the presence of hygroscopic glycol to enhance surface conductivity. Therefore, SEC can be a misleading QC test for electrical reliability when WOA flux residues are present.

Earliest localism was sited on a tree or hill or ford, crossroads or whenceways, where people assembled to talk, (Sax. witan), or trade, (Sax. staple), in eggs, fowl, fish or faggots. From such primitive beginnings many a great city has grown. Settlements and society brought changes; appointed headmen and officials, a cloak of legality, uplifted hands holding “men to witness”. Institutions tend to decay and many of these early forms passed away, but not the principle vital to the system. The parish an ecclesiastical institution, had no place until Saxons, originally heathens, became Christians and time came when Church, cottage and inn filled the lives of men, a state of localism in affairs which endured for centuries. The feudal system decayed and the vestry became the seat of local government. The novels of Thomas Hardy—and English literature boasts of no finer descriptions of life as it once was—depict this authority and the awe in which his smocked countrymen stood of “the vicar in his vestry”. The plague freed serfs and bondsmen, but events, such as the Poor Law of 1601, if anything, revived the parish as the organ of local government, but gradually secular and ecclesiastical aspects were divided and the great population explosion of the eighteenth century created necessity for subdivision of areas, which continued to serve the principle of localism however. The ballot box completed the eclipse of Church; it changed concepts of localism but not its importance in government.

Polyethylene terephthalate (PET) as a fiber molding polymer is widely used in aerospace, electrical and electronic, clothing and other fields. The purpose of this study is to improve the thermal insulation performance of polyethylene terephthalate (PET), the SiO₂ aerogel/PET composites slices and fibers were prepared, and the effects of the SiO₂ aerogel on the morphology, structure, crystallization property and thermal conductivity of the SiO₂ aerogel/PET composites slices and their fibers were systematically investigated.

The mass ratio of purified terephthalic acid and ethylene glycol was selected as 1:1.5, which was premixed with Sb₂O₃ and the corresponding mass of SiO₂ aerogel, and SiO₂ aerogel/PET composites were prepared by direct esterification and in-situ polymerization. The SiO₂ aerogel/PET composite fibers were prepared by melt-spinning method.

The results showed that the SiO₂ aerogel was uniformly dispersed in the PET matrix. The thermal insulation coefficient of PET was significantly reduced by the addition of SiO₂ aerogel, and the thermal conductivity of the 1.0 Wt.% SiO₂ aerogel/PET composites was reduced by 75.74 mW/(m · K) compared to the pure PET. The thermal conductivity of the 0.8 Wt.% SiO₂ aerogel/PET composite fiber was reduced by 46.06% compared to the pure PET fiber. The crystallinity and flame-retardant coefficient of the SiO₂ aerogel/PET composite fibers showed an increasing trend with the addition of SiO₂ aerogel.

The SiO₂ aerogel/PET composite slices and their fibers have good thermal insulation properties and exhibit good potential for application in the field of thermal insulation, such as warm clothes. In today’s society where the energy crisis is becoming increasingly serious, improving the thermal insulation performance of PET to reduce energy loss will be of great significance to alleviate the energy crisis.

In this study, SiO₂ aerogel/PET composite slices and their fibers were prepared by an in situ polymerization process, which solved the problem of difficult dispersion of nanoparticles in the matrix and the thermal conductivity of PET significantly reduced.