• Polymer(Korea)
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• v.39 no.3
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• pp.388-393
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• 2015

Low molecular weight species were extracted from PC and SAN by a solvent extraction method in order to investigate the effect of low molecular weight species on interfacial tension and affinity between PC and SAN. From the analysis of molecular weight distribution by the GPC, it was confirmed that the low molecular weight species were effectively eliminated by the solvent extraction. Interfacial tension measurements and morphological observation were carried out with the PC and SAN of which the low molecular weight species were extracted. Interfacial tension was increased and the infinity was decreased for the extracted PC and SAN pair. This result implied that the low molecular weight species play a role as a compatibilizer between two polymers. Among two polymers, low molecular weight SAN contributes more in the compatibilization. Thus, it is favorable to use SAN containing a larger amount of low molecular weight species in fabrication of PC/ABS blend.

• Korean Chemical Engineering Research
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• v.51 no.6
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• pp.780-783
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• 2013

Recently, it has been reported that low molecular weight laminarin had the enhanced biological activities. In this study, molecular structure of low molecular weight laminarin prepared by ionizing irradiation was studied. Low molecular weight laminarin samples of 13.5, 8.5, 7, and 6 kDa were obtained from 15 kDa laminarin by irradiation. From gel permeation chromatography data, low molecular weight laminarin was shown to have low polydispersity. To define the changes of functional groups in laminarin with different molecular weights, Fourier-transform infrared analysis was carried out. There was found no significant changes of functional groups in low molecular weight laminarin, except the increase of carbonyl group. The granular fissures from scanning electron microscopy showed the breakage of glycosidic bond in low molecular weight laminarin. These results could be utilized for the investigation of the enhanced biological activities of low molecular weight polysaccharides including laminarin.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.315-318
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• 1988

THE STUDY ABOUT CHARACTERISTICS OF PHOTO RESIST ITSELF (MINIMUM RESOLUTION, DEPTH OF FOCUS MARGIN AND CRITICAL DIMENSION CONTROL LATITUDE) WAS DONE AND REPORTED. THREE TYPES OF PHOTO RESISTS WERE TESTED. THE FIRST IS THE LOW MOLECULAR WEIGHT PHOTO-RESIST SHOWING THE NARROW DISTRIBUTION OF MOLECULAR WEIGHT (LOW MOLECULAR WEIGHT CONTROL TYPE), THE SECOND IS A PHOTO-RESIST CONTAINING THE INNER CONTRAST ENCHANCEMENT MATERIAL (INNER CEM TYPE) AND THE THIRD IS A NORMAL PHOTO-RESIST (HIGH MOLECULAR WEIGHT TYPE). THE INNER CEM TYPE AND THE LOW MOLECULAR WEIGHT CONTROL TYPE PHOTO-RESIST ARE MORE IMPROVED PHOTO-RESISTS. IT PROVED THAT THE MINIMUM RESOLUTION WAS IMPROVED BY 0.2 - 0.3 um, THE DEPTH OF FOCUS MARGIN WAS IMPROVED BY 0.8 - 1.2 um AND THE C.D. CONTROL LATITUIDE WAS IMPROVED.

• Journal of Microbiology and Biotechnology
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• v.33 no.5
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• pp.656-661
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• 2023

The aims of this study were to optimize the preparation of low-molecular-weight collagen using a proteolytic enzyme (alcalase) derived from the feet of Korean native chickens, and to characterize the process of collagen hydrolysis. Foreign bodies from chicken feet were removed using ultrasonication at 28 kHz with 1.36 kW for more than 25 min. The hydrolytic pattern and molecular weight distribution of enzyme-treated collagen from chicken feet were analyzed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and high-performance liquid chromatography, respectively. Ideally, chicken feet should be treated at 100℃ for 8 h to obtain a high collagen content using hot water extraction. The collagen content of the chicken foot extract was 13.9 g/100 g, and the proportion of low-molecular-weight collagen increased with increasing proteolytic enzyme concentration and reaction time. When treated with 1% alcalase, the average molecular weight of collagen decreased rapidly to 4,929 Da within 5 h and thereafter decreased at a slower rate, reaching 4,916 Da after 7 h. Size exclusion chromatography revealed that low-molecular-weight collagen peptides of approximately 1,000-5,000 Da were obtained after hydrolysis with 1% alcalase for 1 h.

• Journal of Korean Neurosurgical Society
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• v.42 no.5
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• pp.377-381
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• 2007

Objective : High-molecular-weight hydroxyethyl starch (HES) compromises blood coagulation more than does low-molecular-weight HES. We compared the effects of low- and high-molecular-weight HES for the treatment of vasospasm and investigated the dose relationship with each other. Methods : Retrospectively, in a series of consecutive 102 patients with subarachnoid hemorrhage (SAH), 35 patients developed clinical symptoms of vasospasm of these fourteen patients were treated with low-molecular weight HES for volume expansion while the other 21 received high-molecular-weight HES as continuous intravenous infusion. Prothrombin time (PT), partial thromboplastin time (PIT), fibrinogen level, and platelet count were all measured prior to initiation, during treatment and after termination of therapy for symptomatic vasospasm. The total dose of HES ranged from 5 L to 14 L and median infusion duration was 10 days. Results : A more pronounced PTT prolongation was observed in high-molecular-weight HES group compared with low-molecular-weight HES group. No other coagulation parameters were altered. Dosage (=duration) shows a positive correlation with PTT. Clinically, significant bleeding episodes were noted in four patients who received high-molecular-weight HES. Conclusion : Coagulopathy was developed in direct proportion to molecular weight of starch and dosages. We propose the extreme caution in the administration of HES solution for the vasospasm treatment.

• Korean Journal of Food Science and Technology
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• v.53 no.6
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• pp.695-700
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• 2021

The purpose of this study was to prepare low-molecular weight collagen using a commercial proteolytic enzyme (Protamex) from collagen extracted from feet of Korean native chicken and to investigate the quality characteristics of this collagen. The collagen content of Korean native chicken feet was 13.9 g/100 g, which was higher than the 6.21 g/100 g of general broilers. It was found that the content of low molecular weight collagen increased as the concentration of proteolytic enzymes and reaction time increased. In particular, reaction with 1% Protamex for 7 h resulted in 55.6% of low molecular weight (1,000-5,000 Da) collagen content, and the average molecular weight was 5,390 Da. Regarding the texture of the enzyme-treated collagen, the collagen with high molecular weight peptides decomposed into low molecular weight peptides, and the gel type could not be formed, whereas the sol type was maintained.

• Journal of the Korean Graphic Arts Communication Society
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• v.18 no.1
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• pp.141-155
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• 2000

To examine how the difference of molecular weight distribution of cellulase influenced the beating process according to surface pore size of the fiber, high molecular weight enzyme and low one were applied to soft wood pulp, hard wood pulp, cotton linter pulp. Some enzymes with the distribution of low molecular weight penetrated into cellulose in the proportion of surface pore size and the results were negative as like : the low viscosity, decrease of refining Yield, decrease of fine fibers content and so on. But in cotton linter pulp in the small surface area, the fiber softness was increased and it had a positive result that the paper intensity was high. Other enzymes with the distribution of high molecular weight had an enzyme reaction on the most surfaces of cellulose. They were effective in eliminating the fuzz of hydrophile fine fibers and the freeness was increased.

• Journal of the Korean Society of Food Science and Nutrition
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• v.21 no.6
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• pp.681-685
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• 1992

Low molecular weight RNA(LMW RNA : 5S rRNA and tRNAs, <150 nucleotides) profiles of several bacteriocin production lactic acid bacteria from pig meats and reference lactic acid bacteria were generated on 10% denaturing polyacrylamide gel electrophoresis. Data evaluation including three molecular weight markers enabled the calculation of relative nucleotide units(RNU) for every band. Gels profiles and RNU evaluations were effective for identification of lactic acid bacteria species. LMW RNA profiles of lactic acid bacteria showed no variation in dependence on APT(All Purpose Tryptone Broth), TSB(Tryptic Soy Broth), MRS(Lactobacilli MRS Broth) different cultural medium.

• The Korean Journal of Food And Nutrition
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• v.22 no.2
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• pp.308-312
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• 2009

In this study, the effects of low molecular weight chitooligosaccharides were assessed. Low molecular weight chitooligosaccharide evidenced no cytotoxicity in in vitro trials with the normal cell line, Vero E6(Africa green monkey kidney cell). The $IC_{50}$ of low molecular weight chitooligosaccharide was $923.20{\mu}g/m{\ell}$. Low molecular weight chitooligosaccharide exhibited in vitro antineoplastic activity in five human tumor(lung carcinoma, bladder carcinoma, colon carcinoma, stomach carcinoma, breast carcinoma) cell lines. The $IC_{50}$ values of low molecular weight chitooligosaccharide on A549, J82, SNU-C4, SNU-1 and ZR75-1 were $477.42{\mu}g/m{\ell}$, $480.40{\mu}g/m{\ell}$, $436.84{\mu}g/m{\ell}$, $373.55{\mu}g/m{\ell}$, and $539.95{\mu}g/m{\ell}$, respectively.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3340-3344
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• 2013

The fabrication of polymer field-effect transistors with good electrical properties requires the minimization of molecular defects caused by low molecular weight (MW) fractions of a conjugated polymer. Here we report that the electrical properties of a narrow bandgap conjugated polymer could be dramatically improved as a result of dipping a thin film into a poor solvent. The dipping time in hexanes was controlled to efficiently eliminate the low molecular weight fractions and concomitantly improve the molecular ordering of the conjugated polymer. The correlation between the structural order and the electrical properties was used to optimize the dipping time and investigate the effects of the low MW fraction on the electrical properties of the resulting thin film.