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The structural characterization of melt-crystallized samples and oriented fibers of syndiotactic copolymers between propene and 1-butene is reported. Melt-crystallized samples of copolymers are crystallized in the form I of syndiotactic polypropylene (s-PP) up to a content of 1-butene of 60−70 mol %, although disorder in the alternation of right- and left-handed helical chains along both axes of the unit cell is present. More ordered modifications, close to the limit ordered, fully antichiral, form I of s-PP are obtained by crystallization at high temperatures only for samples containing small contents of 1-butene (1−2 mol %). The presence of 1-butene prevents that the order in the alternation of right- and left-handed helical chains develops at high crystallization temperatures. Samples with contents of 1-butene higher than 70 mol % crystallize in structures similar to that of form I of syndiotactic poly(1-butene). Fiber samples of copolymers with small content of 1-butene (1−2 mol %) present the same behavior of syndiotactic polypropylene. Stretched fibers are in the trans planar form III of s-PP, which transforms into the isochiral helical form II of s-PP upon the release of the tension. Mixtures of crystals in forms I and II of s-PP are obtained by annealing. With increasing the 1-butene content only the antichiral helical form I of s-PP is observed in the stretched fibers of the copolymers, as well as upon the release of the tension. The presence of 1-butene units, for contents higher than 4 mol %, prevents the formation of the trans planar form III of s-PP by stretching. For these samples the formation of form I of s-PP, instead of the isochiral form II, either in the stretched fibers or upon the release of the tension, is a further evidence that the isochiral helical form II of s-PP can be obtained only from fibers initially in the trans planar form III, through a cooperative conformational transformation which induce the formation of helical chains having the same chirality.

Lithium titanate (Li4Ti5O12/LTO) is one of the materials being developed as an anode in Li-ion battery. LTO has zero-strain properties that do not volume change during charge and discharge, does not cause SEI, and can be used for the high rate. However, LTO has a weakness such as low electrical conductivity of 10[?]13 S/cm and low capacity of 175 mAh/g. Therefore, it needs to be combined with high-capacity materials such as silicon and materials that have high electrical conductivity such as carbon. In this study, the LTO-C/nano-Si composite was made to obtain an anode with high capacity and electrical conductivity. Carbon is added with a variation of 1, 3, and 5 wt% during the sol-gel process, while nano-Si is added by 10 wt% of the total active material ingredient in the slurry making. The carbon added is activated carbon which has previously been activated by using NaOH. Activated carbon is characterized by BET and SEM, while LTO-C/nano-Si composite was characterized by XRD and SEM. For the battery electrochemical performance, EIS, CV, and CD tests are performed. Activated carbon has a surface area of 490,007 m2/g. In this study, the optimum result achieved by the addition of 3% activated carbon (LTO-3%C/nano-Si) with 182.87 O resistivity and 17.14 mAh/g discharge capacity at 20C.

A letter to the editor is presented in response to the article about the financial and business relations of the organization the American Academy of Family Physicians and the beverages manufacturer Coca-Cola Co. in the U.S.

In this work, experimental results are obtained from the behavior of the Discrete Wigner Distribution Function (DWDF), when is applied on a detected image of an object of small dimensions, non-resolved by the optical system (OS). The object is illuminated with a laser source. We verify that for the average of several detected images the DWDF is positive inside a frequency interval of four times the bandwidth of the OS. However, when the object is not a quasi-point source the DWDF has positive and negative values inside the same interval. This is an indication that in this case the object is resolved by the OS. Numerical and experimental results are shown and compared to support this conjecture.