23 research outputs found
Sequence-defined multifunctional polyethers via liquid-phase synthesis with molecular sieving
Synthetic chemists have devoted tremendous effort towards the production of precision synthetic polymers with defined sequences and specific functions. However, the creation of a general technology that enables precise control over monomer sequence, with efficient isolation of the target polymers, is highly challenging. Here, we report a robust strategy for the production of sequence-defined synthetic polymers through a combination of liquid-phase synthesis and selective molecular sieving. The polymer is assembled in solution with real-time monitoring to ensure couplings proceed to completion, on a three-armed star-shaped macromolecule to maximize efficiency during the molecular sieving process. This approach is applied to the construction of sequence-defined polyethers, with side-arms at precisely defined locations that can undergo site-selective modification after polymerization. Using this versatile strategy, we have introduced structural and functional diversity into sequence-defined polyethers, unlocking their potential for real-life applications in nanotechnology, healthcare and information storage
On the absence of zeros in infinite arithmetic progression for certain zeta functions
DOI:
10.1017/S000497271800064
Distribution of -free integers over a floor function set
http://dx.doi.org/10.1017/S000497271200033
Consecutive square-free numbers in Piatetski-Shapiro sequences
http://dx.doi.org/10.1017/S000497271200033
Sonication synthesis of micro-sized silver nanoparticle/oleic acid liquid marbles: A novel SERS sensing platform
All rights reserved. Liquid marbles are entities made of a small amount of liquid encapsulated by micro/nano scale particles. The functionality of liquid marbles depends on both the core liquid and particle coating. In this work, functional silver nanoparticle (Ag NPs)/oleic acid liquid marbles are developed using Ag NPs to encapsulate micro-sized oleic acid liquid spheres, which is achieved via sonication. We demonstrate that both the size of the encapsulated spheres and the order of the Ag NPs coating are a function of the sonication time. These micro-sized liquid marbles are investigated for sensing an organic thiolate as a model material. Their capacity for increasing solar light absorption and energy conversion into heat is also studied. The liquid marbles generated after sonication for 60 min show the strongest Raman peak signals which originate from the thiolate. They also demonstrate the highest solar energy absorption. We ascribe these enhancements to the increased surface area of the Ag NPs/oleic acid spheres and the optimum order of Ag NPs to produce the strongest surface enhanced Raman scattering. The liquid marbles can be used for the development of future biosensors and solar-thermal absorbers
Gallic acid conjugated with gold nanoparticles: antibacterial activity and mechanism of action on foodborne pathogens
Narintorn Rattanata,1 Sompong Klaynongsruang,1 Chanvit Leelayuwat,2 Temduang Limpaiboon,2 Aroonlug Lulitanond,2 Patcharee Boonsiri,3 Sirinart Chio-Srichan,4 Siriwat Soontaranon,4 Supagorn Rugmai,4 Jureerut Daduang2 1Department of Biochemistry, Faculty of Science, 2Centre for Research and Development of Medical Diagnostic Laboratories, Faculty of Associated Medical Sciences, 3Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen, 4Synchrotron Light Research Institute (Public Organization), Nakhon Ratchasima, Thailand Abstract: Foodborne pathogens, including Plesiomonas shigelloides and Shigella flexneri B, are the major cause of diarrheal endemics worldwide. Antibiotic drug resistance is increasing. Therefore, bioactive compounds with antibacterial activity, such as gallic acid (GA), are needed. Gold nanoparticles (AuNPs) are used as drug delivery agents. This study aimed to conjugate and characterize AuNP–GA and to evaluate the antibacterial activity. AuNP was conjugated with GA, and the core–shell structures were characterized by small-angle X-ray scattering and transmission electron microscopy. Antibacterial activity of AuNP–GA against P. shigelloides and S. flexneri B was evaluated by well diffusion method. AuNP–GA bactericidal mechanism was elucidated by Fourier transform infrared microspectroscopic analysis. The results of small-angle X-ray scattering showed that AuNP–GA conjugation was successful. Antibacterial activity of GA against both bacteria was improved by conjugation with AuNP because the minimum inhibitory concentration value of AuNP–GA was significantly decreased (P<0.0001) compared to that of GA. Fourier transform infrared analysis revealed that AuNP–GA resulted in alterations of lipids, proteins, and nucleic acids at the bacterial cell membrane. Our findings show that AuNP–GA has potential for further application in biomedical sciences.Keywords: gold nanoparticles, gallic acid, antibacterial activity, foodborne bacteria, small-angle X-ray scattering (SAXS) 
Level of agreement between self-rated and clinician-rated instruments when measuring major depressive disorder in the Thai elderly: a 1-year assessment as part of the THAISAD study
Nahathai Wongpakaran,1 Tinakon Wongpakaran,1 Kamonporn Wannarit,2 Nattha Saisavoey,2 Manee Pinyopornpanish,1 Peeraphon Lueboonthavatchai,3 Nattaporn Apisiridej,4 Thawanrat Srichan,5 Ruk Ruktrakul,5 Sirina Satthapisit,6 Daochompu Nakawiro,7 Thanita Hiranyatheb,7 Anakevich Temboonkiat,8 Namtip Tubtimtong,9 Sukanya Rakkhajeekul,9 Boonsanong Wongtanoi,10 Sitthinant Tanchakvaranont,11 Putipong Bookkamana,12 Usaree Srisutasanavong,1 Raviwan Nivataphand,3 Donruedee Petchsuwan4 1Faculty of Medicine, Chiang Mai University, Chiang Mai, Kingdom of Thailand; 2Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Kingdom of Thailand; 3Faculty of Medicine, Chulalongkorn University, Bangkok, Kingdom of Thailand; 4Trang Hospital, Trang, Kingdom of Thailand; 5Lampang Hospital, Lampang, Kingdom of Thailand; 6Khon Kaen Hospital, Khon Kaen, Kingdom of Thailand; 7Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Kingdom of Thailand; 8Phramongkutklao Hospital, Bangkok, Kingdom of Thailand; 9Faculty of Medicine Naresuan University, Pitsanulok, Kingdom of Thailand; 10Srisangwal Hospital, Mae Hong Son, Kingdom of Thailand; 11Queen Savang Vadhana Memorial Hospital, Chonburi, Kingdom of Thailand; 12Faculty of Science, Chiang Mai University, Chiang Mai, Kingdom of Thailand Purpose: Whether self-reporting and clinician-rated depression scales correlate well with one another when applied to older adults has not been well studied, particularly among Asian samples. This study aimed to compare the level of agreement among measurements used in assessing major depressive disorder (MDD) among the Thai elderly and the factors associated with the differences found. Patients and methods: This was a prospective, follow-up study of elderly patients diagnosed with MDD and receiving treatment in Thailand. The Mini International Neuropsychiatric Inventory (MINI), 17-item Hamilton Depression Rating Scale (HAMD-17), 30-item Geriatric Depression Scale (GDS-30), 32-item Inventory of Interpersonal Problems scale, Revised Experience of Close Relationships scale, ten-item Perceived Stress Scale (PSS-10), and Multidimensional Scale of Perceived Social Support were used. Follow-up assessments were conducted after 3, 6, 9, and 12 months. Results: Among the 74 patients, the mean age was 68±6.02 years, and 86% had MDD. Regarding the level of agreement found between GDS-30 and MINI, Kappa ranged between 0.17 and 0.55, while for Gwet's AC1 the range was 0.49 to 0.91. The level of agreement was found to be lowest at baseline, and increased during follow-up visits. The correlation between HAMD-17 and GDS-30 scores was 0.17 (P=0.16) at baseline, then 0.36 to 0.41 in later visits (P<0.01). The PSS-10 score was found to be positively correlated with GDS-30 at baseline, and predicted the level of disagreement found between the clinicians and patients when reporting on MDD. Conclusion: The level of agreement between the GDS, MINI, and HAMD was found to be different at baseline when compared to later assessments. Patients who produced a low GDS score were given a high rating by the clinicians. An additional self-reporting tool such as the PSS-10 could, therefore, be used in such under-reporting circumstances. Keywords: late-life depression, measurement, correlatio
Synthesis of Sequence-Controlled Copolymers Using Time-Regulated Additions of N -Substituted Maleimides in Styrenic Radical Polymerizations
International audienc