Synthesis,characterization and biophysical evaluation of the 2D Ti2CTx MXene using 3D spheroid-type cultures

MXenes are novel 2-D materials which have been extensively investigated for use in advanced biocomposites, water purification, biosensors, bioimaging and antibacterial systems. However, the knowledge associated with the mechanism of cytotoxic response is still limited to lack of verification against 3D spheroid-type cultures. Herein, we present a report on the in vitro cytotoxicity of Ti₂CT_x MXene against cervical cancer cell lines (HeLa) in a form of 3D spheroid with comparison to 2D cell culture system. Ti₂CT_x MXenes can be characterized by their multi-layered structure that is produced by the efficient elimination of Al and appearance of the surface functional groups. The biological results with 2D and 3D HeLa indicated that the Ti₂CT_x MXene was moderately cytotoxic to cells and the cytotoxicity was dose dependent. Our results showed that the toxicity of MXenes is potentially due to direct contact of the Ti₂CT_x MXene with the cell membrane wall. The Raman spectra suggested that the Ti₂CT_x MXenes interfered with the cytoplasmic proteins’ conformation and the surrounding microenvironment. This inherently modified the biochemistry of the cell membrane and caused cell apoptosis. This paper contributes to the pool of knowledge regarding the biocompatibility and biophysical properties of Ti₂CT_x MXene.     

Design of polyurethane fibers: Relation between the spinning technique and the resulting fiber topology

Properties or characteristics of fibers are affected by their topology. In fact, these topologies are found to have significant impacts in the functionalities of many applications. Hence, in this study, the relations between the spinning techniques and the topology of the resulting fibers are studied with the aim to provide a guideline for future reference where fibers with certain topology can be fabricated to suit specific applications. For this purpose, polyurethane is chosen to be the raw material to fabricate the fibers due to its versatility to be applied in various fields. The surface morphology, structures, and alignments of the fibers are studied. It is found that the polymer solution properties largely influence the mechanisms in the spinning process and can significantly affect the topology of the fibers. For instance, viscous solutions enable the spinning of coiled and smooth fibers, whereas conductive solutions encourage the splaying of the solution jet which results in the spinning of straight fibers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47706.     

Superposition of sphero-cylindrical lenses using contour graphs

BACKGROUND: The superposition of thin sphero-cylindrical lenses with arbitrary angles between cylindrical axes is sometimes required in a clinical setting. For example, it may be useful in some instances to perform an overrefraction which, added to the spectacle or toric contact lens in place on the eye, yields a final correcting lens. METHODS: Computer calculations have been used to create contour graphs allowing a graphical solution to the problem of combining sphero-cylindrical lenses. Although conceptually strightforward, the method has not been presented before. RESULTS: The use of contour graphs to superpose sphero-cylindrical lenses is shown by examples to be accurate and much simpler than calculational methods. CONCLUSIONS: Lacking a pre-programmed computer, the method of contour graphs offers a practical method of combining sphero-cylindrical lenses.     

On the detection of dominant points on digital curves

A parallel algorithm is presented for detecting dominant points on a digital closed curve. The procedure requires no input parameter and remains reliable even when features of multiple sizes are present on the digital curve. The procedure first determines the region of support for each point based on its local properties, then computes measures of relative significance (e.g. curvature) of each point, and finally detects dominant points by a process of nonmaximum suppression. This procedure leads to the observation that the performance of dominant points detection depends not only on the accuracy of the measure of significance, but also on the precise determination of the region of support. This solves the fundamental problem of scale factor selection encountered in various dominant point detection algorithms. The inherent nature of scale-space filtering in the procedure is addressed, and the performance of the procedure is compared to those of several other dominant point detection algorithms, using a number of examples     

History of lactation and breast cancer risk

A self-administered questionnaire was completed by 1,018 women diagnosed with breast cancer during 1988-1989 identified through the British Columbia Cancer Registry and by 1,025 controls selected at random from the Provincial Voters List. Parous premenopausal women who had never nursed (odds ratio (OR) = 1.3, 95% confidence interval (CI) 0.9-2.0) or who had lactated for 1 month or less (OR = 1.8, 95% CI 1.3-2.5) had an increased risk of breast cancer adjusted for age and parity, compared with women who had breast-fed 2 months or longer. The risk was particularly elevated (OR = 3.0, 95% CI 1.6-5.4) among women who reported having tried to nurse, but who were unsuccessful. Among women who nursed for at least 2 months, there was an indication of decreasing risk with increasing duration of nursing. Among postmenopausal parous women, no relation between lactation history and breast cancer risk was evident.     

Optimal generating kernels for image pyramids by piecewise fitting

A novel class of generating kernels for image pyramids is introduced. When these kernels are convolved with intensity functions of images, continuous piecewise surfaces composed of polynomial tensor products are fitted to the intensity functions. The fittings are optimal in the sense that the mean square error between them and the original intensity functions is minimized. Two members of the class are introduced, and symmetry, normalization, unimodality, and equal contribution properties are proved. These kernels possess attractive properties such as small window size, fast inverse transformation, and minimum error. Experiments show that they compare favorably with existing ones in terms of mean square error