Mechanical properties and physicochemical characteristics of cotton fibers during combing process.

This study employs a combination of experiments and molecular dynamics to analyze the mechanical properties and surface damage characteristics of cotton fibers during the combing process. Additionally, it investigates the alterations in physical and chemical properties at the atomic scale resulting from mechanical damage. Raw cotton (RC) is combed to 1st combed cotton (1st CC), 2nd combed cotton (2nd CC) and 3rd combed cotton (3rd CC). It was found that the mechanical properties and crystallinity showed an increasing and then decreasing trend with the process of combing, and the degree of surface tearing increased, and the binding energy of C and O shifted to a lower position. The breaking strength of cotton fibers first increased by 7.4 % and then decreased by 11 % and 7.7 % respectively, and the crystallinity was CrI (RC) = 70.8 %, CrI (1st CC) = 75.3 %, CrI (2nd CC) = 72.7 %, and CrI (3rd CC) = 71.8 % respectively. The C-O bond and the C-C bond at the amorphous regions are broken after combing lead to the cellulose chain to break, resulting in a decrease in the breaking strength of the fibers. The C-O bond as well as the C-O-C bond angles changes significantly during stretching, and the increase in ordering of the amorphous regions causes an increase in crystallinity.

Friction Properties of Crystalline Cellulose Sliding on Chromium under Water Lubrication Based on Molecular Dynamics Simulations.

This work studies the friction and wear behaviors of chromium (hard material) and crystalline cellulose (soft material) under water lubrication considering the loading and sliding velocity on friction force, temperature of contact interfaces, and worn atoms from the atomic view. The change of friction force with sliding velocity is greater than that with loading, and it is easier to obtain a stable friction at high velocity. The average friction force in the stabilization gradually increases with loading and velocity, and the growth rate decreases with loading, while it increases with velocity. The temperature of contact interfaces at the beginning of sliding changes rapidly and gradually becomes stable. The temperature at the stabilization increases distinctly with velocity, while it does not change much with loading. Both the loading and sliding velocity have an important influence on the wear of soft material; it is noticed that the amount of worn atoms increases close to exponentially with velocity and linearly with loading. However, the wear of hard material changes less with increasing loading and sliding velocity.

A new analytical platform for potential point-of-care testing of circulating tumor cells.

It is of significance to detect circulating tumor cells (CTCs) in whole blood using transportable instruments at the point of care to assist evaluating chemotherapeutic efficacy and recurrence risk of cancer patients. However, the current widely used detection methods either require expensive and complex equipments, need complicated enrichment steps, or produce high rates of false positive and/or negative results. Aiming for solving the two critical challenges involved in instrumentation miniaturization and simplification of sample preparation for POCT of CTCs without sacrificing the detection sensitivity and accuracy, this work reports a custom-built, automatic, large field-of-view microscopic CTC cytometer and a novel enrichment strategy based on a synthesized peptide ligand discovered from One-Bead One-Compound library screening. The custom-built microscope has compact size, low weight and efficient cost while still maintaining a detection limit of as low as 5 target objects. The simplified sample preparation utilized a novel peptide LXW7 functionalized to magnetic beads and allows for rapid, highly selective and sensitive detection of CTCs. This analytical platform may fulfill the unmet need for possible point-of-care CTC counting, and provide a new option for early diagnosis of cancers and convenient evaluation of chemotherapeutic efficacy and cancer recurrence.

A smart preparation strategy for point-of-care cellular counting of trace volumes of human blood.

Blood counting is one of the most commonly ordered clinical assays, and is often part of the basis for initial diagnosis and screening for disease. While substantial prior research has shown the ability of portable instruments to accurately produce blood counts through image- or flow-based cytometry, these methods require complex sample preparation using either costly commercial imaging chambers or complicated reagents. To address these issues, in this paper we developed a method to prepare trace volumes of whole blood aimed at portable blood counting. The strategy is based on pre-storing dry-form reagents and fabricating a specifically designed cell counter. In order to obtain total cell counts for red blood cells, platelets, and 3-part differentials of white blood cells, two parallel counting chambers with different depths are made from cost- and environmentally friendly materials using soft lithography. As little as 1 µl of whole blood is prepared with pre-stored reagents in centrifuge vials, whereas red blood cells are sphered and white blood cells are stained at the same time. Driven by the capillary force, prepared blood samples enter the hydrophilic chambers automatically. Monolayers of cells are formed when the blood dilution factors and the chamber depths are co-optimized. Combined with our previous custom-built instrument and automated analysis algorithm, the sample preparation strategy allows producing counting results with excellent agreement to a gold-standard clinical hematology instrument. The success of this preparation method may further advance applications of our technology for global use in low-resource settings where central hematology laboratories are not accessible. Graphical abstract Graphical Abstract.

Azo polymer microspherical cap array: soft-lithographic fabrication and photoinduced shape deformation behavior.

In this work, azo polymer microspherical cap arrays possessing unique photoprocessible properties have been fabricated through a soft-lithographic contact printing approach. In the process, hexagonal polystyrene (PS) colloidal arrays, obtained by the vertical deposition method, were used as masters. Poly(dimethylsiloxane) (PDMS) stamps with aligned hemisphere air voids on the surfaces were obtained by casting the precursor against the colloidal arrays. By using the stamps and a solution of an epoxy-based azo polymer (BP-AZ-CA) as "ink", the microspherical cap arrays were fabricated by pressing the "inked" surfaces against substrates. Uniform 2D arrays of the submicrometer spherical caps could be obtained on the substrates after peeling off the stamps and drying. The characteristic sizes of the arrays depended on some adjustable features, such as the diameters of PS spheres and concentrations of the "inks" used in the process. After exposure to a linearly polarized Ar+ laser single beam, the spherical caps could be stretched along the polarization direction, and the arrays were consequently transformed into ellipsoidal cap arrays. Upon irradiation of interfering p-polarized Ar+ laser beams, only the spherical caps in the bright fringes were deformed by the light irradiation, which resulted in more complicated surface relief patterns. The observation gives another well-defined example of the photoinduced mass migration in the submicrometer scale. The approach can potentially be applied to fabrication of microlens arrays with different converging rate in two directions.