Customization of Soft Tissue Expanders: Improving Safety, Accuracy, and Efficiency for Treatment of Large and Complicated Skin Lesions.

BACKGROUND: Soft tissue expansion is a common technique for restoring large skin defects. Fixed-type expanders may be inappropriate for the following reasons: (1) the shapes and sizes of the defects vary in different patients; and (2) the bulged base of the fixed-type expander does not fit the curve of the human body, which may induce complications such as concave deformities or nerve palsy from continuous mechanical compression. The customized expander adjusts better to the shape and the topography of the expansion site compared with the fixed-type expander. It improves expansion efficiency and reduces complications caused by compression. METHODS: Between 2016 and 2022, customized soft tissue expansion was performed in 38 patients with skin lesions, including giant congenital melanocytic nevi and postburn scars. This series of patients included patients with a specific donor site shape that is unsuitable for fixed-type expanders. An expander was customized according to the shape of the donor site and then implanted in the subcutaneous pocket. After the expander reached a sufficient volume, the expander was removed, and the extra expanded skin flap was transferred to resurface the skin lesion. In the follow-up, the outcome and the complications were recorded. RESULTS: All the customized expanders fit not only the dimension but also the topography of the donor site. During expansion, 2 patients experienced leakage of the expander, and 3 patients suffered a skin rupture. In the remaining 33 patients, the expansion was successfully completed, and the expanded flaps restored the skin lesions as designed. The color and texture of the skin flaps remained satisfactory after long-term follow-up. CONCLUSIONS: Unlike fixed-type expanders, our customized expanders make it possible for "accurate" expansion, irrespective of the dimension and topography of the donor area. Customization of the expander helps increase efficiency and reduce complications caused by undue compression.

Influence of Molecular Symmetry and Terminal Substituents on the Morphology and OFET Characteristics of S,N-Heteropentacenes.

Many heteroacenes have been extensively studied to improve device performances; however, the morphological effects stemmed from the chemical modification on a multiscale remain less explored. In this research, five axisymmetric S,N-heteropentacenes (DTPT, DTPT-Ph, DTPT-CN, DTPT-PYCN, and DTPT-BTCN) are studied to reveal the influences of molecular symmetry and end-capping substituents on the structure-property relationship, the thermal stability, crystallization behavior, film morphology, and OFET performance. Phase behavior was probed by differential scanning calorimetry (DSC), while the quality of the crystal array and structural details was investigated by optical microscopy (OM) and grazing-incidence wide-angle X-ray scattering (GIWAXS). The analytic results reveal that (1) the parent axisymmetric S,N-heteropentacene, DTPT, is hard to crystallize, which hinders the preparation of high-quality crystal arrays for the OFET application. (2) The incorporation of π-conjugated electron-withdrawing (π-EW) endcaps that provide extended conjugation length and enhanced molecular polarity is required to form oriented crystal arrays to deliver reasonable OFET characteristics. (3) The π-EW endcaps with conformational freedom, such as -BTCN, due to the asymmetric feature of benzothiadiazole (BT), can hinder bulk phase crystallization and cause conformational disorder in the crystal array. Hence, the tradeoff of introducing the end-substituents to reinforce the poor crystalline nature of S,N-heteroacenes should be carefully considered.

Influences of Structural Modification of S, N-Hexacenes on the Morphology and OFET Characteristics.

Although chemical modifications on conjugated molecules are widely applied for the purpose of improving processability and device performances, the effect of the modification was far less investigated. Here, five S, N-hexacenes are studied to reveal the influences of (1) the lateral alkyl chain, (2) the terminal group (thiophene vs benzene), and (3) the end-capping phenyl group of the hexacenes on the morphology and organic field-effect transistor (OFET) performances. Crystal arrays of the hexacenes were prepared via polydimethylsiloxane (PDMS)-assisted crystallization (PAC) prior to morphological and OFET characterizations. The lattice structures and crystal quality of the hexacenes were evaluated by microscopy and diffraction techniques including single-crystal diffractometer, electron diffraction, and grazing incidence wide-angle X-ray scattering. The systematic analyses led to the following conclusions: (1) the bulkier alkyl side chain assists to form more densely packed crystals with less structural defects; (2) the terminal thiophene rings bring about higher-lying EHOMO, more ordered phase, and crystal orientation, whereas the terminal benzene rings deteriorate the structural order of the active layer and result in the liquid crystal phase; and (3) the phenyl end caps ameliorate the morphological order, intermolecular overlapping, thermal stability and elevate EHOMO. Thus, EH-DTPTt-Ph delivers the highest µh, contributing to high-lying EHOMO, well-oriented crystal array with a longer correlation length, and suitable lattice orientation. This systematic research provides the aspects about the effects of the functionalized S, N-hexacenes on the morphology and OFET characteristics, which is anticipated to be useful for the molecular design of heteroacenes.

Roles of 3-Ethylrhodanine in Attaining Highly Ordered Crystal Arrays of Ambipolar Diketopyrrolopyrrole Oligomers.

Until now, only limited DPP oligomers delivered ambipolar semiconductor characteristics. To develop a facile strategy of preparing ambipolar mono-DPP oligomers, two dithienyl diketopyrrolopyrrole (DPPT) based-conjugated molecules, DPPT-RD and DPPT-DCV, which contain 3-ethylrhodanine (RD) and dicyano-2-vinyl (DCV) end substituents were synthesized. The influences of the -RD end substituents on the molecular properties, solid-state morphology, and OFET performances of the DPPT oligomer were investigated. The UV-vis absorption and CV results showed that the RD end substituents provide the DPPT oligomer suitable EHOMO and ELUMO for hole and electron injection from the Au source-drain electrodes. Moreover, the RD end substituents also improve the crystalline nature of the DPPT oligomer. That is, DPPT-RD can form crystal arrays with good lattice orientation, larger crystalline size, and without polymorphism. With those properties, DPPT-RD thus display ambipolar characteristic with µh and µe reaching 2.16 × 10-2 and 7.27 × 10-2 cm2 V-1 s-1, respectively.

Estimating Percent Crystallinity of Polyethylene as a Function of Temperature by Raman Spectroscopy Multivariate Curve Resolution by Alternating Least Squares.

We have recently demonstrated a methodology to estimate the percent crystallinity (PC) of polymers directly with Raman spectroscopy and multivariate curve resolution (MCR) by alternating least-squares (ALS). In the MCR-ALS methodology, the Raman spectrum of a semicrystalline polymer is separated into two constituent components (crystalline and molten/amorphous) and their corresponding concentrations. The methodology necessitates that the Raman spectrum at any temperature be a linear combination of two MCR spectral components (one molten and one crystalline). This is true in the case of simple systems such as crystalline pendant alkyl domains in polymers (Samuel et al. Anal. Chem. 2016, 88, 4644). However, in the case of main chain polymer crystals (e.g., polyethylene), the situation can be complicated owing to several molecular changes in the lattice in addition to conformational reorganizations during melting. Under this circumstance, a simple two-state model may not be adequate and we describe the modifications required to treat such systems, keeping the basic principles of the proposed methodology unchanged. A comparative study with wide-angle X-ray scattering (WAXS) and Raman spectroscopy is also performed to substantiate our findings. In addition to estimating percent crystallinity (PC), our methodology is capable of revealing additional information, such as interchain interactions in crystal lattice, that in principle will help distinguishing polymorphic transformations, subtle changes in lamellar lattice dimensions, and other phase changes in polymers.

Plasma power controlled deposition of SiOx with manipulated Si Quantum Dot size for photoluminescent wavelength tailoring.

Plasma power controlled PECVD of SiO(x) under SiH(4)/N(2)O gas mixture with manipulated Si quantum dot (Si-QD) size for tailoring photoluminescent (PL) wavelength is demonstrated. The incomplete decomposition of N(2)O at high plasma power facilitates Si-rich SiO(x) deposition to enlarge O/Si composition ratio and to shrink Si-QD size. As RF plasma power increases from 20 to 70 W, the O/Si ratio is increased from 1 to 1.6 and the average Si-QD size is reduced from 4.5 to 1.7, which increases Si-QD density from 3.2 x 10(17) to 3.02 x 10(18) cm(-3) and blue-shifts PL wavelength from 780 to 380 nm.