scholarly journals Fluorinated and Bio-Based Polyamides with High Transparencies and Low Yellowness Index

Polymers ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1311 ◽  
Author(s):  
Kenji Takada ◽  
Yuko Mae ◽  
Tatsuo Kaneko
Keyword(s):  
Heat Resistance ◽  
Water Repellency ◽  
General Characteristic ◽  
The Other ◽  
Aromatic Diamines ◽  
Yellowness Index ◽  
High Transparency ◽  
Aromatic Dicarboxylic Acid ◽  
Truxillic Acid ◽  
Polyamide Film

Bio-based polyamides with high transparency and low yellowness were synthesized using 4,4′-bis(trifluoroacetamido)-α-truxillic acid (ATA-F1) and 4,4′-bis(pentafluoropropionamido)-α-truxillic acid (ATA-F2) as a fluoroalkylated aromatic dicarboxylic acid, and various aromatic diamines. The introduction of fluorine side chains improved the transparency of the polyamide film, and suppressed its yellowness. On the other hand, water repellency, which should be a general characteristic of the fluorinated polymers, was not observed. By using ATA-F1 and various aromatic diamines, aromatic and fluorinated polyamides were obtained. In addition, these also demonstrated a high transparency and a low yellowness index. The heat resistance properties of all the obtained polyamides was over 250 °C, and the characteristics of the bio-based polyamides from 4-aminocinnamic acid derivatives were retained.

scholarly journals Preparation and Characterization of Semi-Alicyclic Polyimides Containing Trifluoromethyl Groups for Optoelectronic Application

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1532
Author(s):  
Mei Zhang ◽  
Weili Liu ◽  
Xia Gao ◽  
Peng Cui ◽  
Tao Zou ◽  
...  
Keyword(s):  
Heat Resistance ◽  
High Heat ◽  
Dielectric Constants ◽  
Dielectric Anisotropy ◽  
Good Mechanical Property ◽  
Cutoff Wavelength ◽  
High Heat Resistance ◽  
Aromatic Diamines ◽  
Yellowness Index ◽  
Trifluoromethyl Groups

Transparent polyimides (PI) films with outstanding overall performance are attractive for next generation optoelectronic and microelectronic applications. Semi-alicyclic PIs derived from alicyclic dianhydrides and aromatic diamines have proved effective to prepare transparent PIs with high transmittance. To optimize the combined properties of semi-alicyclic PIs, incorporating bulky trifluoromethyl groups into the backbones is regarded as a powerful tool. However, the lack of fundamental understanding of structure–property relationships of fluorinated semi-alicyclic PIs constrains the design and engineering of advanced films for such challenging applications. Herein, a series of semi-alicyclic PIs derived from alicyclic dianhydrides and trifluoromethyl-containing aromatic diamines was synthesized by solution polycondensation at high temperature. The effects of alicyclic structures and bulky trifluoromethyl groups on thermal, dielectric and optical properties of PIs were investigated systematically. These PI films had excellent solubility, low water absorption and good mechanical property. They showed high heat resistance with Tg in the range of 294–390 °C. It is noted that tensile strength and thermal stability were greatly affected by the rigid linkages and alicyclic moieties, respectively. These films exhibited obviously low refractive indices and significantly reduced dielectric constants from 2.61 to 2.76, together with low optical birefringence and dielectric anisotropy. Highly transparent films exhibited cutoff wavelength even as low as 298 nm and transmittance at 500 nm over 85%, displaying almost colorless appearance with yellowness index (b*) below 4.2. The remarkable optical improvement should be mainly ascribed to both weak electron-accepting alicyclic units and bulky electron-withdrawing trifluoromethyl or sulfone groups. The present work provides an effective strategy to design molecular structures of optically transparent PIs for a trade-off between solution-processability, low water uptake, good toughness, high heat resistance, low dielectric constant and excellent optical transparency.

scholarly journals Municipal Representatives’ Accounts of Decision-Making Practices during Geriatric Case Conferences

2017 ◽  
Vol 23 (45) ◽  
pp. 129
Author(s):  
Søren Beck Nielsen
Keyword(s):  
Senior Citizens ◽  
General Characteristic ◽  
The Other ◽  
Residential Home ◽  
Residential Homes ◽  
Social Actors ◽  
Naturally Occurring ◽  
Case Conferences ◽  
The Relationship ◽  
Elderly Citizen

This article addresses questions of elucidation in talk-in-interaction. How do social actors give accounts of what they are doing? To what degree do actors sustain a taken-for-granted level of reasoning? The analysis is based upon naturally occurring data consisting of a corpus of audio recorded case conferences at various geriatric wards in Danish hospitals. The article elaborates one of the important insights of Harold Garfinkel regarding the relationship between discourse and social interaction: as a general characteristic, people tend to treat their fellow interlocutors’ conversational contributions as adequate for-all-practical-purposes. Specifically, the article investigates how Danish municipal representatives account for their decisions about whether or not senior citizens are to be referred to residential homes. This practice, I demonstrate, is characterized by non-explicitness with regards to rules and regulations. Instead, municipal representatives make use of developmental discourse: a worsened condition is used to justify a referral to a residential home. On the other hand, an improved condition is used to justify that an elderly citizen is not referred to a residential home.

Poly(amide) oligomers with silarylene and/or germarylene units – synthesis, characterization and thermal studies

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Luis H. Tagle ◽  
Claudio A. Terraza ◽  
Angel Leiva ◽  
Patricia Alvarez
Keyword(s):  
Main Chain ◽  
Effective Interaction ◽  
Thermal Studies ◽  
The Other ◽  
Spectroscopic Techniques ◽  
Aromatic Diamines ◽  
Packing Factor ◽  
Degradation Temperature ◽  
General Terms ◽  
Acid Dichloride

AbstractTen poly(amide) oligomers were prepared from four acid dichlorides and two full-aromatic diamines, the latter containing silicon or germanium in their structure. The polymers, which contain Et/Me, Et/Et and nBu/nBu combinations on heteroatom of the acid dichloride moiety, were characterized by spectroscopic techniques, including 29Si NMR. The yields obtained and the ηιnh values established were low, indicating the low molecular weight nature of the polymers. Thermal stability was also evaluated by TG and DSC techniques. When a methyl group was replaced by a Et, the Tg of the poly(amides) (PAs) was increased in accordance with the gain in the flexibility of the chain. However and in general terms, the PAs with nBu groups show the inverse effect. Probably, the possibility of an effective interaction between these side chains affects negatively the flexibility of the main chain. On the other hand, PAs that contain single silicon in their structure show lower Tg values than the Ge-containing PAs. For the other heteroatom combinations, similar results were obtained. This fact does not agree with the lower size of silicon atom which should increase the molecular rigidity and therefore their Tg values. Probably, the influence of the side groups is decisive in hindering the chain rotation. The thermal degradation temperature (TDT) changed in agreement with the packing factor of the chains which was depending on the size of substitute groups. So, when Et group was replaced by nBu as lateral group, lower TDT were recovered. With respect to the heteroatoms used in the main chain, the TDT values do not show a clear tendency.

Thermal Resistance of Listeria spp. in Milk

1991 ◽  
Vol 54 (1) ◽  
pp. 12-14 ◽  
Author(s):  
JOE G. BRADSHAW ◽  
JAMES T. PEELER ◽  
ROBERT M. TWEDT
Keyword(s):  
High Temperature ◽  
Thermal Resistance ◽  
Heat Resistance ◽  
Raw Milk ◽  
The Other ◽  
Time Processing ◽  
Listeria Ivanovii ◽  
High Temperature Short Time ◽  
The Difference ◽  
Short Time

The thermal resistance of one strain each of Listeria ivanovii, L. seeligeri, and L. welshimeri and three L. monocytogenes strains was determined in raw and sterile milk. Listeria spp. suspended in milk at concentrations of 1 × 105 cells/ml were heated at temperatures ranging from 52.2 to 71.1°C for various contact times. The heat resistance of L. monocytogenes appeared somewhat greater than that of the other Listeria spp. in both milks, but the difference was not statistically significant (α = 0.05). High-temperature, short-time processing is adequate for pasteurization of raw milk.

scholarly journals Effect of infant meal home preparation temperature on surviving of Bacillus cereus sensu lato: A case of Bechar city, Algeria

2021 ◽  
Vol 25 (2) ◽  
pp. 201-210
Author(s):  
Hassiba Difallah ◽  
Mohammed Ziane ◽  
Olfa Ben Braïek ◽  
Mohammed Bouamra ◽  
Habiba Louzim
Keyword(s):  
Heat Resistance ◽  
Bacillus Cereus ◽  
Storage Conditions ◽  
The Other ◽  
Preparation Temperature ◽  
Meal Preparation ◽  
Production Preparation ◽  
And Storage ◽  
Bacterial Concentrations ◽  
Bacillus Cereus Sensu Lato

Abstract This work aimed to enumerate the Bacillus cereus sensu lato from infant’s flour sampled at Béchar city and evaluate its resistance to different heating conditions during meal preparation patterns at home. Our findings revealed a prevalence of 74% with 2.4 to 3.9 CFU/g in the analyzed samples. Regarding the heat resistance at 90 °C to 98 °C, our results showed heat resistance variability which depends on the isolate, for example, D90 °C and zT °C values varied from 3.24 to 5.52 min and 11.56 to 89.74 °C respectively. Then, the decimal reduction (n) was calculated at all preparation temperatures (50, 60, 70, 80, 90 and 100 °C). Low “n” was observed with the preparation at T≤50 °C as recommended by the fabricant. However, at the other temperatures, high “n” was observed at 100°C with median and 95th values of 2.22 and 12.36 respectively. Therefore, bacterial concentrations (99th) were estimated at 0.124 log CFU/g for 100 °C. These concentrations could be increased with bacterial growth during meal storage and then achieve critical concentrations. Thus, the results of this work highlight the interest to establish a risk assessment for babies and to improve the production, preparation, and storage conditions of the infant’s flour.

scholarly journals Leuangtengdong: Analysis of a Hmong Song

2021 ◽  
Vol 7 ◽  
pp. 69-76
Author(s):  
Paula Stefanini
Keyword(s):  
General Characteristic ◽  
Social Experience ◽  
Social Contexts ◽  
The Other ◽  
Melodic Line ◽  
Fitting In ◽  
The Given ◽  
Point Of Departure

This article is an analysis of ‘Leuangtengdong’, a Hmong song melody which was recorded and transcribed by Jähnichen in 2000, while documenting a collection of Hmong songs in Laos. This new article is an effort to analyze melodic patterns of the song while considering its historical and social contexts through the personal gaze of the author with a specific background in singing and social experience. It is important to mention that the language sung in the song was unkown and that the emphasis of the analysis is on the musical shape. Finally, there is a conclusion regarding this song fitting in Jähnichen’s hypothesis on Hmong song melodies which states that most musical phrases do not repeat; all lines are different in pitch, order and length; pitch order and intervals can indicate a specific type (of song); singers do not know which type they sing, only analysis shows; and analysis cannot prove ethnic groupings. "Very interesting is the general characteristic of generating absolutely individual melodic lines in each example and in all the other recordings there was no one song with a repetition of a single melodic line. Avoiding repetitions is therefore a remarkable sign of Hmong song melodies.” (Jähnichen, 2011: 126). The given core hypothesis was the point of departure in this analytical article.

scholarly journals Bioactive Multilayer Polylactide Films with Controlled Release Capacity of Gallic Acid Accomplished by Incorporating Electrospun Nanostructured Coatings and Interlayers

2019 ◽  
Vol 9 (3) ◽  
pp. 533 ◽  
Author(s):  
Luis Quiles-Carrillo ◽  
Nestor Montanes ◽  
José Lagaron ◽  
Rafael Balart ◽  
Sergio Torres-Giner
Keyword(s):  
Sustained Release ◽  
Gallic Acid ◽  
In Vitro Release ◽  
The Other ◽  
High Transparency ◽  
Release Capacity ◽  
Release Studies ◽  
Vitro Release ◽  
Saline Medium

The present research reports on the development of bi- and multilayer polylactide (PLA) films by the incorporation of electrospun nanostructured PLA coatings and interlayers containing the antioxidant gallic acid (GA) at 40 wt% onto cast-extruded PLA films. To achieve the bilayer structures, submicron GA-loaded PLA fibers were applied on 200-µm cast PLA films in the form of coatings by electrospinning for 1, 2, and 3 h. For the multilayers, the cast PLA films were first coated on one side by electrospinning, then sandwiched with 10-µm PLA film on the other side, and the resultant whole structure was finally thermally post-treated at 150 °C without pressure. Whereas the bilayer PLA films easily delaminated and lacked transparency, the multilayers showed sufficient adhesion between layers and high transparency for deposition times during electrospinning of up to 2 h. The incorporation of GA positively contributed to delaying the thermal degradation of PLA for approximately 10 °C, as all films were thermally stable up to 345 °C. The in vitro release studies performed in saline medium indicated that the GA released from the bilayer PLA films rapidly increased during the first 5 h of immersion while it stabilized after 45–250 h. Interestingly, the PLA multilayers offered a high sustained release of GA, having the capacity to deliver the bioactive for over 1000 h. In addition, in the whole tested period, the GA released from the PLA films retained most of its antioxidant functionality. Thus, during the first days, the bilayer PLA films can perform as potent vehicles to deliver GA while the multilayer PLA films are able to show a sustained release of the natural antioxidant for extended periods.

Latex Compounding of GR-S

1944 ◽  
Vol 17 (3) ◽  
pp. 711-718
Author(s):  
H. F. O'Connor ◽  
C. W. Sweitzer
Keyword(s):  
Carbon Black ◽  
Heat Resistance ◽  
High Temperatures ◽  
Room Temperature ◽  
Milling Time ◽  
Mixing Time ◽  
The Other ◽  
Stress Strain ◽  
Convenient Form ◽  
Latex Compounding

Abstract The more important findings in this study can be summarized as follows. (1) A satisfactory technique has been worked out for compounding GR-S in latex form, either with carbon alone or with carbon plus the other compounding ingredients. (2) Latex compounding of GR-S results in notable improvements in stress-strain properties. (3) Latex compounding of GR-S results in outstanding improvements in heat resistance properties, without any loss in rebound. (4) Latex compounding of GR-S results in lower modulus, higher elongation and higher subpermanent set. The increased set is significant, since it is accompanied by maintained rebound. Besides giving improved quality, latex compounding offers practical advantages and possibilities. These are listed below: (1) Latex compounding makes possible a reduction in the total milling time. This saving amounts to at least 10 per cent for carbon latex compounds and up to 50 per cent for complete latex compounds. The mixing time normally required in the Banbury is certainly not required. (2) Latex compounding makes possible cooler handling of the GR-S. Since the carbon is added to the latex at room temperature, no high temperatures are involved during its incorporation as in Banbury mixing. (3) Latex compounding makes possible cleaner handling of carbon, since it is added to the latex and is, therefore, mixed in the rubber before milling. If desired, the handling of carbon black could thus be transferred in toto to the polymer plants. This offers some interesting possibilities. (4) Latex compounding to the black crumb stage, followed by sheeting and baling, should provide a convenient and economical means for shipping black, particularly for transoceanic deliveries. There would also be important savings in containers. (5) The black latex crumb may provide a convenient form of compounded GR-S for extrusion and related operations.

THE PHYSIOLOGY AND NATURAL RELATIONSHIPS OF THE MOTILE, SPOREFORMING SARCINAE

1962 ◽  
Vol 8 (5) ◽  
pp. 795-808 ◽  
Author(s):  
R. E. MacDonald ◽  
Shirley W. MacDonald
Keyword(s):  
Heat Resistance ◽  
The Other ◽  
Sporosarcina Ureae ◽  
Cross Reactions ◽  
The Family

Eleven strains of Sarcina ureae were compared to members of the genus Sarcina and to three species of Bacillus. Biochemically these 11 strains are very much alike. They appear to be more closely allied to members of the genua Bacillus than to the sarcinae, both on the basis of biochemical patterns and DNA composition. The spores of S. ureae are very similar to spores of the bacilli in their degree of heat resistance, requirements for formation, and composition. Serological differences among the 11 strains of S. ureae were observed, although no cross reactions with the spore forming bacilli or the other sarcinae were found, We propose that S. ureae (Beijerinck) Löhnis be called Sporosarcina ureae (Beijerinck) Kluyver and van Niel and that it be classified as a member of the family Bacillaceae.

A double-edged sword: Metaphor and metonymy through pictures for learning idioms

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Kris Ramonda
Keyword(s):  
The Other ◽  
Semantic Transparency ◽  
High Transparency ◽  
L2 Learners ◽  
The Impact ◽  
Picture Type ◽  
Metaphor And Metonymy

AbstractThis study examined the impact that metaphorical pictures and semantic transparency had on meaning recall of English idioms for L2 learners. Twenty-seven idioms of differing semantic transparency (low, mid, and high) were selected and two types of pictures were drawn for each idiom. One picture type was a literal only representation while the other was a literal+figurative representation. These idioms and picture conditions (no picture, literal only, and literal+figurative) were counterbalanced and presented to student participants (n=64) via a PowerPoint input treatment. The delayed posttests measured meaning recall of the idioms’ L1 paraphrased meaning. The data showed that in absolute terms, literal-figurative pictures promoted better retention of meaning at all levels of transparency, but this finding was most robust for high-transparency idioms. However, a number of pictures, especially those with metonymical elements, led to overspecification, which has wider implications for pictorial input in general.

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