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2022 ◽  
Vol 17 (1) ◽  
Author(s):  
Daewon Kang ◽  
Sourav Sarkar ◽  
Kyung-Soo Kim ◽  
Soohyun Kim

AbstractThin-film saturable absorbers (SAs) are extensively used in mode-locked fiber laser due to the robust and simple application methods that arise because SAs are alignment-free and self-standing. Single-walled carbon nanotubes (SWCNTs) are the most suitable low dimensional material uesd for SAs because of their high nonlinearity and the wavelength control of absorption based on tube diameters. The most challenging problem with the use of CNT-based thin film SAs is thermal damage caused during high power laser operation, which mainly occurs due to aggregation of CNTs. We have demonstrated improved thermal damage resistance and enhanced durability of a film-type SA based on functionalization of SWCNTs, which were subjected to a mechanical functionalization procedure to induce covalent structural modifications on the SWCNT surface. Increased intertube distance was shown by X-ray diffraction, and partial functionalization was shown by Raman spectroscopy. This physical change had a profound effect on integration with the host polymer and resolved aggregation problems. A free-standing SA was fabricated by the drop casting method, and improved uniformity was shown by scanning electron microscopy. The SA was analyzed using various structural and thermal evaluation techniques (Raman spectroscopy, thermogravimetric analysis, etc.). Damage tests at different optical powers were also performed. To the best of our knowledge, a comprehensive analysis of a film-type SA is reported here for the first time. The partially functionalized SWCNT (fSWCNT) SA shows significant structural integrity after intense damage tests and a modulation depth of 25.3%. In passively mode-locked laser operation, a pulse width of 152 fs is obtained with a repetition rate of 77.8 MHz and a signal-to-noise ratio of  75 dB. Stable operation of the femtosecond fiber laser over 200 h verifies the enhanced durability of the fSWCNT SA.


Gels ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 257
Author(s):  
Rubén D. Múnera-Tangarife ◽  
Efraín Solarte-Rodríguez ◽  
Carlos Vélez-Pasos ◽  
Claudia I. Ochoa-Martínez

Intensive research on biodegradable films based on natural raw materials such as carboxymethyl cellulose (CMC) has been performed because it enables the production of transparent films with suitable barrier properties against oxygen and fats. Considering the importance of the production of this type of film at the industrial level, a scalable and continuous drying method is required. Refractance window-conductive hydro drying (RW-CHD) is a sustainable and energy-efficient method with high potential in drying this kind of compound. The objective of this study was to evaluate the factors (CMC thickness, heating water temperature, and film type) and radiation penetration depth that affect drying time and energy consumption. It was found that drying time decreased with increasing temperature and decreasing thickness. Similarly, energy consumption decreased with decreasing temperature and thickness. However, the drying time and energy consumed per unit weight of product obtained were equivalent when drying at any of the thicknesses evaluated. Film type had little effect on time and energy consumption compared to the effects of temperature and CMC thickness. The radiation penetration depth into the CMC was determined to be 1.20 ± 0.19 mm. When the thickness was close to this value, the radiation energy was better utilized, which was reflected in a higher heating rate at the beginning of drying.


2021 ◽  
Vol 2 ◽  
Author(s):  
Takumi Kishi ◽  
Toshinori Fujie ◽  
Hiroyuki Ohta ◽  
Shinji Takeoka

Neurotransmitters, which are responsible for the signal transduction of nerve cells in the brain, are linked not only to various emotions and behaviors in our daily life, but also to brain diseases. Measuring neurotransmitters in the brain therefore makes a significant contribution to the progress of brain science. The purpose of this study is to develop a flexible thin film-type sensor that can electrochemically measure dopamine (DA) selectively and with high sensitivity. The thin-film sensor was prepared by printing gold colloidal ink on a polyimide film with a thickness of 25 µm—which the most flexible of the films examined that could maintain the buckling load (1 mN) required for insertion into the brain. The electrode (DA-PPy electrode) was then prepared by electropolymerization of polypyrrole (PPy) using DA as a template. The flexural rigidity of the sensor was 4.3 × 103 nNm, which is the lowest of any neurotransmitter sensors reported to date. When a DA solution (0–50 nM) was measured with the DA-PPy electrode using square-wave voltammetry (SWV), the slope of the calibration curve was 3.3 times higher than that of the PPy only negative control electrode, indicating an improvement in sensitivity by molecular imprinting with DA. The sensor was used to measure 0−50 nM norepinephrine (NE) and serotonin (5-HT), and the slope of the DA calibration curve at 0.24 V (19 ± 4.4 nA/nM) was much greater than those of NE (0.99 ± 3.3 nA/nM) and 5-HT (2.5 ± 2.4 nA/nM) because the selectivity for DA was also improved by molecular imprinting.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Hyun Hee Park

PurposeThis study investigates the effect of consumers' brand attitude changes according to the fashion film type. Furthermore, it examines the psychological mechanism by engagement and consumer fantasy proneness. This study is meaningful because it provides a more in-depth understanding of the use of fashion film as a means of consumer-oriented persuasion communication.Design/methodology/approachThis research uses a 2(fashion film type: narrative vs non-narrative) × 2(consumer fantasy proneness: high vs low) mixed factorial design to test the hypotheses. ANOVA and the PROCESS macro mounted on SPSS was used to test hypotheses.FindingsThe group with high consumer fantasy proneness showed more changes in brand attitude when exposed to non-narrative than narrative fashion films, but the group with low consumer fantasy proneness showed no significant difference in brand attitude change according to the fashion film type. In addition, when consumer fantasy proneness is high, media and brand engagement for non-narrative fashion films increase sequentially, resulting in a greater change in brand attitude, whereas these psychological mechanisms do not work in groups with low consumer fantasy proneness.Practical implicationsFashion brands should identify their respective target group when producing fashion films and choose differentiated narrative forms. In the case of pursuing a fantastic aesthetic value, the non-narrative type induces more attention and curiosity from consumers than the narrative type, which affects the feeling of a special bond or relevance with the brand.Originality/valueThis study has value in that it demonstrates the rationale for why a fashion brand needs to select a differentiated content structure according to the aesthetic value pursued when making a fashion film in branding work.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Abeer Al Mohtar ◽  
Moisés L. Pinto ◽  
Artur Neves ◽  
Sofia Nunes ◽  
Daniele Zappi ◽  
...  

AbstractPreserving culture heritage cellulose acetate-based historical films is a challenge due to the long-term instability of these complex materials and a lack of prediction models that can guide conservation strategies for each particular film. In this work, a cellulose acetate degradation model is proposed as the basis for the selection of appropriate strategies for storage and conservation for each specimen, considering its specific information. Due to the formulation complexity and diversity of cellulose acetate-based films produced over the decades, we hereby propose a hybrid modeling approach to describe the films degradation process. The problem is addressed by a hybrid model that uses as a backbone a first-principles based model to describe the degradation kinetics of the pure cellulose diacetate polymer. The mechanistic model was successfully adapted to fit experimental data from accelerated aging of plasticized films. The hybrid model considers then the specificity of each historical film via the development of two chemometric models. These models resource on gas release data, namely acetic acid, and descriptors of the films (manufacturing date, AD-strip value and film type) to assess the current polymer degradation state and estimate the increase in the degradation rate. These estimations are then conjugated with storage conditions (e.g., temperature and relative humidity, presence of adsorbent in the film’s box) and used to feed the mechanistic model to provide the required time degradation simulations. The developed chemometric models provided predictions with accuracy more than 87%. We have found that the storage archive as well as the manufacturing company are not determining factors for conservation but rather the manufacturing date, off gas data as well as the film type. In summary, this hybrid modeling was able to develop a practical tool for conservators to assess films conservation state and to design storage and conservation policies that are best suited for each cultural heritage film.


AIP Advances ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 065232
Author(s):  
Takehiro Esaki ◽  
Hiroki Uchiyama ◽  
Yousuke Matsukuma

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