Natural rubber, produced by coagulation of the latex from the tree Hevea brasiliensis, is an important biopolymer used in many applications for its outstanding properties. Besides polyisoprene, latex is rich in many nonisoprene components such as carbohydrates, proteins and lipids and thereby constitutes a favourable medium for the development of micro-organisms. The fresh rubber coagula obtained by latex coagulation are not immediately processed, allowing the development of various microbial communities. The time period between tree tapping and coagula processing is called maturation, during which an evolution of the properties of the corresponding dry natural rubber occurs. This evolution is partly related to the activity of micro-organisms and to the modification of the biochemical composition. This review synthesizes the current knowledge on microbial populations in latex and natural rubber coagula of H. brasiliensis and the changes they induce on the biochemistry and technical properties of natural rubber during maturation.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1111/jam.12556 | DOI Listing |
J Esthet Restor Dent
January 2025
Department of Dental Materials and Prosthodontics, Sao Paulo State University (UNESP), School of Dentistry, Araçatuba, São Paulo, Brazil.
Objective: To evaluate the influence of in situ acid erosion on the structural and optical properties of nanoparticulate bisacrylic resin with different surface treatments, evaluating surface roughness (Ra), knoop microhardness (KHN), color change (ΔE, ΔL, ΔC, ΔH), contrast (CR) and translucency (TP).
Methods: Eighty specimens were made (n = 10 per group) and the following surface treatments were applied: U-unpolished; A-polishing with Astropol rubber tips (Ivoclar); S-Biscover LV surface sealant (Bisco) and S-Palaseal surface sealant (kulzer). For the in situ experiment, 10 volunteers wore an intraoral appliance containing eight specimens (two specimens per experimental group), with only one specimen from each experimental group being subjected to the acid process.
BMC Oral Health
January 2025
Department of Endodontics, Faculty of Dentistry, Erciyes University, Kayseri, Turkey.
Background: This study assessed stress distributions in simulated mandibular molars filled with various materials after the removal of fractured instruments from the apical thirds of the root canals.
Methods: Finite element models of the mesial and distal root canals were created, where fractured instruments were assumed to be removed using a staging platform established with a modified Gates-Glidden bur (Woodpecker, Guangxi, P.R.
Chemosphere
January 2025
Faculty of Chemistry, University of Science, Vietnam National University, Hanoi, 19 Le Thanh Tong, Hanoi, 10000, Viet Nam. Electronic address:
Chlorinated paraffins (CPs) are chemical additives mostly composed of polychlorinated alkanes (PCAs) which may impact on the environment and human health; however, little is known about their presence in Southeast Asia. To fill this knowledge gap, we assessed 74 PCA homolog groups commonly referred to as short-chain (SCCPs: PCAs-C), medium-chain (MCCPs: PCAs-C), and long-chain CPs (LCCPs: PCAs-C) in technical CP mixtures (n = 4) and polymer samples (n = 49), including recycled plastics, collected in Vietnam in 2023. The contents of measured PCA homolog groups in technical CP mixtures were 86,000-930,000 mg/kg for PCAs-C; 85,000-990,000 mg/kg for PCAs-C; and 23,000-180,000 mg/kg for PCAs-C.
View Article and Find Full Text PDFJ Phys Chem B
January 2025
College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China.
Reline, which is composed of choline chloride and urea in a molar ratio of 1:2, is the first and most extensively studied deep eutectic solvent (DES). In certain applications, reline is blended with organic solvents, dimethyl sulfoxide (DMSO) in most cases, to gain improved properties. Therefore, it is crucial to have a profound understanding of the impact of DMSO on the dynamics and structures of the species in the binary mixtures.
View Article and Find Full Text PDFSci Adv
January 2025
School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
Electronic skins endow robots with sensory functions but often lack the multifunctionality of natural skin, such as switchable adhesion. Current smart adhesives based on elastomers have limited adhesion tunability, which hinders their effective use for both carrying heavy loads and performing dexterous manipulations. Here, we report a versatile, one-size-fits-all robotic adhesive skin using shape memory polymers with tunable rubber-to-glass phase transitions.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!