The influence of mechanical action on felting shrinkage of wool fabric in the tumble dryer

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Felting shrinkage of untreated wool fabric occurs easily during tumble drying. Mechanical action applied on fabrics plays a significant part in felting shrinkage of wool fabric. In general, the more severe the mechanical action of a washing or drying machine, the more rapid is felting shrinkage. However, both the degree of mechanical action applied on fabric and the type of mechanical action could influence felting shrinkage of untreated wool fabric. In the current study, fabric movement and felting shrinkage of untreated wool fabric at different rotation speeds of the drum in a tumble dryer under no heating condition were studied. Based on the different fabric movements at different rotation speeds of the tumble drum, the extent of impact force and rubbing force at different rotation speeds were assessed through their ranking. The total mechanical action applied on the fabric was expressed by the percentage of thread removal of “thread removal fabric” during drying process. The results showed that lowest mechanical force on fabrics could be achieved when the higher rotation speed of the drum was used for drying wool fabrics in tumble dryers, and it could prevent wool felting shrinkage. It was also found that falling of the fabric followed by impact to the drum wall caused less felting shrinkage than sliding with rubbing between fabrics. Therefore, falling movement of fabric could be a potential method to dry wool fabric in drying machines without causing severe felting shrinkage

Dimensional change of wool fabrics in the process of a tumble-drying cycle

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Currently domestic tumble dryers are popularly used for drying garments; however, excessive drying and the inappropriate way of tumble agitation could waste energy and cause damage to or the dimensional change of garments. Shrinkage of wool fabrics during tumble drying causes a serious problem for wool garments. The current study investigated the shrinkage of untreated and Chlorine-Hercosett–finished wool fabrics at different drying times. Temperature of air in the tumble dryer, temperature of fabric, moisture content of fabric, and dimensional change at different drying times were measured. For the duration of the tumble drying, the rise of fabric temperature and the reduction of moisture content on the wool fabric were investigated to explore their relationship to the shrinkage of wool fabrics in the tumble-drying cycle. It was found that the tumble-drying process can be divided into different stages according to the temperature change trend of wool fabrics. The shrinkage mechanisms of the untreated and the treated fabrics were different. The dimensional change of untreated wool fabric was caused mainly by felting shrinkage during tumble drying. Chlorine-Hercosett–finished wool fabric can withstand the tumble-drying process without noticeable felting shrinkage due to the surface modification and resin coating of surface scales of wool fibers. The finding from the current research provides further understanding of the shrinkage behavior of wool fabrics during the tumble-drying process, leading to optimizing operational parameters at specific stages of a tumble-drying cycle

A platinum shell for ultraslow ligand exchange: unmodified DNA adsorbing more stably on platinum than thiol and dithiol on gold

Due to the ultraslow ligand exchange rate on Pt, non-thiolated DNA is adsorbed on platinum nanoparticles (PtNPs) more stably than thiolated and even dithiolated DNA on AuNPs. Adsorption kinetics, capacity and stability are systematically compared as a function of DNA sequence. The Pt conjugates can tolerate extreme pH, salt, and thiol molecules. Taking advantage of the optical properties of AuNPs and the extreme stability of DNA on PtNPs, DNA-functionalized Au@Pt NPs are prepared using a cost-effective and more stable bioconjugation method. The DNA-directed assembly of non-thiolated DNA conjugates is also demonstrated.University of Waterloo || Natural Sciences and Engineering Research Council || Foundation for Shenghua Scholar of Central South University || National Natural Science Foundation of China || Grant No. 21301195 China Scholarship Council || CSC, Grant No. 20140637011

Fluorescent sensors using DNA-functionalized graphene oxide

The final publication is available at Springer via http://dx.doi.org/10.1007/s00216-014-7888-3In the past few years, graphene oxide (GO) has emerged as a unique platform for developing DNA-based biosensors, given the DNA adsorption and fluorescence-quenching properties of GO. Adsorbed DNA probes can be desorbed from the GO surface in the presence of target analytes, producing a fluorescence signal. In addition to this initial design, many other strategies have been reported, including the use of aptamers, molecular beacons, and DNAzymes as probes, label-free detection, utilization of the intrinsic fluorescence of GO, and the application of covalently linked DNA probes. The potential applications of DNA-functionalized GO range from environmental monitoring and cell imaging to biomedical diagnosis. In this review, we first summarize the fundamental surface interactions between DNA and GO and the related fluorescence-quenching mechanism. Following that, the various sensor design strategies are critically compared. Problems that must be overcome before this technology can reach its full potential are described, and a few future directions are also discussed.University of Waterloo || Natural Sciences and Engineering Research Council || Ontario Ministry of Research and Innovation || Foundation for Shenghua Scholar || National Natural Science Foundation of China || Grant No. 81301258, 21301195 Postdoctoral Science Foundation of Central South University and Hunan province ||Grant No. 124896 China Postdoctoral Science Foundation || Grant No. 2013M540644 Hunan Provincial Natural Science Foundation of China || Grant No. 13JJ4029 Specialized Research Fund for the Doctoral Program of Higher Education of China || Grant No. 2013016212007

Tandem Phosphorothioate Modifications for DNA Adsorption Strength and Polarity Control on Gold Nanoparticles

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Applied Materials & Interfaces, copyright © American Chemical Society after peer review and technical editing by publisher. To access the final edited and published work see Zhou, W., Wang, F., Ding, J., & Liu, J. (2014). Tandem Phosphorothioate Modifications for DNA Adsorption Strength and Polarity Control on Gold Nanoparticles. ACS Applied Materials & Interfaces, 6(17), 14795–14800. https://doi.org/10.1021/am504791bUnmodified DNA was recently used to functionalize gold nanoparticles via DNA base adsorption. Compared to thiolated DNA, however, the application of unmodified DNA is limited by the lack of sequence generality, adsorption polarity control and poor adsorption stability. We report that these problems can be solved using phosphorothioate (PS) DNA. PS DNA binds to gold mainly via the sulfur atom and is thus less sequence dependent. The adsorption affinity is ranked to be thiol > PS > adenine > thymine. Tandem PS improves adsorption strength, allows tunable DNA density, and the resulting conjugates are functional at a low cost.University of Waterloo || Natural Sciences and Engineering Research Council || Foundation for Shenghua Scholar of Central South University || National Natural Science Foundation of China || Grant No. 2130119

Aptamer-based biosensors for biomedical diagnostics

Aptamers are single-stranded nucleic acids that selectively bind to target molecules. Most aptamers are obtained through a combinatorial biology technique called SELEX. Since aptamers can be isolated to bind to almost any molecule of choice, can be readily modified at arbitrary positions and they possess predictable secondary structures, this platform technology shows great promise in biosensor development. Over the past two decades, more than one thousand papers have been published on aptamer-based biosensors. Given this progress, the application of aptamer technology in biomedical diagnosis is still in a quite preliminary stage. Most previous work involves only a few model aptamers to demonstrate the sensing concept with limited biomedical impact. This Critical Review aims to summarize progress that might enable practical applications of aptamers for biological samples. First, general sensing strategies based on the unique properties of aptamers are summarized. Each strategy can be coupled to various signaling methods. Among these, a few detection methods including fluorescence lifetime, flow cytometry, upconverting nanoparticles, nanoflare technology, magnetic resonance imaging, electronic aptamer-based sensors, and lateral flow devices have been discussed in more detail since they are more likely to work in a complex sample matrix. The current limitations of this field include the lack of high quality aptamers for clinically important targets. In addition, the aptamer technology has to be extensively tested in a clinical sample matrix to establish reliability and accuracy. Future directions are also speculated to overcome these challenges.University of Waterloo || Natural Sciences and Engineering Research Council || Foundation for Shenghua Scholar of Central South University |

Alternative quantization of the Hamiltonian in loop quantum cosmology II: Including the Lorentz term

Since there are quantization ambiguities in constructing the Hamiltonian constraint operator in isotropic loop quantum cosmology, it is crucial to check whether the key features of loop quantum cosmology are robust against the ambiguities. In this paper, we quantize the Lorentz term of the gravitational Hamiltonian constraint in the spatially flat FRW model by two approaches different from that of the Euclidean term. One of the approaches is very similar to the treatment of the Lorentz part of Hamiltonian in loop quantum gravity and hence inherits more features from the full theory. Two symmetric Hamiltonian constraint operators are constructed respectively in the improved scheme. Both of them are shown to have the correct classical limit by the semiclassical analysis. In the loop quantum cosmological model with a massless scalar field, the effective Hamiltonians and Friedmann equations are derived. It turns out that the classical big bang is again replaced by a quantum bounce in both cases. Moreover, there are still great possibilities for the expanding universe to recollapse due to the quantum gravity effect.Comment: 8 pages, 2 figure

The influence of moisture content on shrinkage of wool fabrics during domestic tumble drying process

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Shrinkage of wool fabrics caused during tumble drying is a serious defect. In the drying process, the felting shrinkage of wool fabrics was influenced by the moisture content and temperature of wool fabric as well as mechanical action being applied on the wool fabric. In the current study, the relationship between moisture content of wool fabrics and shrinkage was studied in the drying programs under no heating condition or heated condition. This study also analyzed shrinkage behaviors of the untreated wool fabric and the Chlorine-Hercosett treated wool fabric with different moisture contents. For the untreated wool fabric, moisture content in the fabric could influence the mechanical properties of wool fibers, resulting in the different extent of felting shrinkage of wool fabric during tumble drying. For the Chlorine-Hercosett treated wool fabric at different initial moisture contents, there was no obvious variation in the length change under no heating condition, but a slight difference in the shrinkage under heated condition. The study could lead to the new guidance for efficient drying of wool fabric with less felting shrinkage

2-Aminopurine-modified DNA homopolymers for robust and sensitive detection of mercury and silver

The final publication is available at Elsevier via http://dx.doi.org/10.1016/j.bios.2016.08.033 © 2017. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Heavy metal detection is a key topic in analytical chemistry. DNA-based metal recognition has advanced significantly producing many specific metal ligands, such as thymine for Hg2+ and cytosine for Ag+. For practical applications, however, robust sensors that can work in a diverse range of salt concentrations need to be developed, while most current sensing strategies cannot meet this requirement. In this work, 2-aminopurine (2AP) is used as a fluorescence label embedded in the middle of four 10-mer DNA homopolymers. 2AP can be quenched up to 98% in these DNA without an external quencher. The interaction between 2AP and all common metal ions is studied systematically for both free 2AP base and 2AP embedded DNA homopolymers. With such low background, Hg2+ induces up to 14-fold signal enhancement for the poly-T DNA, and Ag+ enhances up to 10-fold for the poly-C DNA. A detection limit of 3 nM is achieved for both metals. With these four probes, silver and mercury can be readily discriminated from the rest. A comparison with other signaling methods was made using fluorescence resonance energy transfer, graphene oxide, and SYBR Green I staining, respectively, confirming the robustness of the 2AP label. Detection of Hg2+ in Lake Huron water was also achieved with a similar sensitivity. This work has provided a comprehensive fundamental understanding of using 2AP as a label for metal detection, and has achieved the highest fluorescence enhancement for non-protein targets. (C) 2016 Elsevier B.V. All rights reserved.University of Waterloo; Natural Sciences and Engineering Research Council of Canada (NSERC) [386326]; Foundation for Shenghua Scholar of Central South University; National Natural Science Foundation of China [21301195]; China Scholarship Council (CSC) [201406370116

A highly specific sodium aptamer probed by 2-aminopurine for robust Na+ sensing

Sodium is one of the most abundant metals in the environment and in biology, playing critical ecological and physiological roles. Na+ is also the most common buffer salt for nucleic acids research, while its specific interaction with DNA has yet to be fully studied. Herein, we probe a highly selective and robust Na+ aptamer using 2-aminopurine (2AP), a fluorescent adenine analog. This aptamer has two DNA strands derived from the Ce13d DNAzyme. By introducing a 2AP at the cleavage site of the substrate strand, Na+ induces similar to 40% fluorescence increase. The signaling is improved by a series of rational mutations, reaching > 600% with the C(10)A(20) double mutant. This fluorescence enhancement suggests relaxed base stacking near the 2AP label upon Na+ binding. By replacing a non-conserved adenine in the enzyme strand by 2AP, Na+-dependent fluorescence quenching is observed, suggesting that the enzyme loop folds into a more compact structure upon Na+ binding. The fluorescence changes allow for Na+ detection. With an optimized sequence, a detection limit of 0.4 mM Na+ is achieved, reaching saturated signal in less than 10 s. The sensor response is insensitive to ionic strength, which is critical for Na+ detection.University of Waterloo, the Natural Sciences and Engineering Research Council of Canada (NSERC); Foundation for Shenghua Scholar of Central South University and the National Natural Science Foundation of China [21301195]; Fellowship from the China Scholarship Council (CSC) [201406370116 to W.Z.]. Funding for open access charge: Natural Sciences and Engineering Research Council of Canada (NSERC)