[An original reconstruction technique for double upper white lip defect]. / Une technique originale de réparation d'une double perte de substance de l'hémilèvre supérieure blanche.

INTRODUCTION: Herein we report a case of a surgical repair of double substance loss along the nasolabial groove by means of a double superior advancement flap from the cheek to the upper lip that we have here called the "double jigsaw puzzle" flap. OBSERVATION: A 58-year-old man underwent surgery for 2 basal cell carcinomas located in the right white upper lip. The two lesions were first removed and the two defects were then carried over to the cheek symmetrically along the nasolabial groove. Two triangular "lugs" were excised on both sides to allow horizontal advancement of the cheek to the upper lip to fill the 2 gaps from the upper lip excisions like 2 pieces of a puzzle. The nasolabial groove was then recreated by deep anchoring stitches, with suturing comprising superficial stitches. DISCUSSION: This surgical flap can be created quickly and easily and yields good aesthetic results in the immediate postoperative period and in the longer term, and the scar is totally masked within the nasolabial fold. The only limitation to a good aesthetic outcome is the presence of a small area of hairless skin within what constitutes an area of hair growth in male subjects.

Characterisation and aerosolisation of mannitol particles produced via confined liquid impinging jets.

Mannitol particles, produced by spray drying (SD), have been used commercially (Aridol) in bronchial provocation test. In this study, we propose an alternative method to produce inhalable mannitol powders. The elongated mannitol particles (number median length 4.0microm, and axial ratio of 3.5) were prepared using a confined liquid impinging jets (CLIJs) followed by jet milling (JM). Spray dried and jet milled raw mannitol particles were compared in an attempt to assess the performance of the particles produced by the new method. Aerosol performance of the three different powders (CLIJ, SD, and JM) was relatively poor (fine particle fraction or FPF(loaded) below 15%) when dispersed by the Rotahaler. Dispersion through the Aeroliser led to better aerosol performance of the CLIJ mannitol (FPF(loaded) 20.3%), which is worse than the JM (FPF(loaded) 30.3%) and SD mannitol particles (FPF(loaded) 45.7%) at 60 L/min, but comparable (FPF(loaded) 40.0%) with those of the JM (FPF(loaded) 40.7%) and SD (FPF(loaded) 45.5%) powders at 100L/min. Hence, the optimum use of these elongated mannitol particles can be achieved at increased air flow with a more efficient inhaler. In addition to crystallinity, morphology, and particle size distribution, the surface energies of these powders were measured to explain the differences in aerosol performance. A major advantage of using the CLIJ method is that it can be scaled up with a good yield as the precipitate can be largely collected and recovered on a filter, compared with spray drying which has a low collection efficiency for fine particles below 2microm.

Functionalized graphene sheets for polymer nanocomposites.

Polymer-based composites were heralded in the 1960s as a new paradigm for materials. By dispersing strong, highly stiff fibres in a polymer matrix, high-performance lightweight composites could be developed and tailored to individual applications. Today we stand at a similar threshold in the realm of polymer nanocomposites with the promise of strong, durable, multifunctional materials with low nanofiller content. However, the cost of nanoparticles, their availability and the challenges that remain to achieve good dispersion pose significant obstacles to these goals. Here, we report the creation of polymer nanocomposites with functionalized graphene sheets, which overcome these obstacles and provide superb polymer-particle interactions. An unprecedented shift in glass transition temperature of over 40 degrees C is obtained for poly(acrylonitrile) at 1 wt% functionalized graphene sheet, and with only 0.05 wt% functionalized graphene sheet in poly(methyl methacrylate) there is an improvement of nearly 30 degrees C. Modulus, ultimate strength and thermal stability follow a similar trend, with values for functionalized graphene sheet- poly(methyl methacrylate) rivaling those for single-walled carbon nanotube-poly(methyl methacrylate) composites.

Investigating the microenvironments of inhomogeneous soft materials with multiple particle tracking.

We develop a multiple particle tracking technique for making precise, localized measurements of the mechanical microenvironments of inhomogeneous materials. Using video microscopy, we simultaneously measure the Brownian dynamics of roughly one hundred fluorescent tracer particles embedded in a complex medium and interpret their motions in terms of local viscoelastic response. To help overcome the inherent statistical limitations due to the finite imaging volume and limited imaging times, we develop statistical techniques and analyze the distribution of particle displacements in order to make meaningful comparisons of individual particles and thus characterize the diversity and properties of the microenvironments. The ability to perform many local measurements simultaneously allows more precise measurements even in systems that evolve in time. We show several examples of inhomogeneous materials to demonstrate the flexibility of the technique and learn new details of the mechanics of the microenvironments that small particles explore. This technique extends other microrheological methods to allow simultaneous measurements of large numbers of probe particles, enabling heterogeneous samples to be studied more effectively.

Enzymatic degradation of guar and substituted guar galactomannans.

Enzymatic degradation of guar galactomannan is studied using gel permeation chromatography (GPC) and steady shear viscometry. In very dilute polymer solutions, reaction rate increases with first-order kinetics with substrate concentration. In the intermediate concentration regime, the enzyme/polymer binding saturates, and the degradation kinetics is zero-order. The observations are in accord with a Michaelis-Menton kinetics model. The Michaelis-Menton parameter, Km and Vmax, were determined to be 0.6 mM and 7.8 x 10(-10) mol/(mL s) for guar at pH = 7, where the maximal velocity of the reaction, Vmax, was measured in terms of the molar concentration of glycosidic bonds broken per unit time. However, as the solution increases in concentration, the reaction rate decreases and the enzyme diffusion through the concentrated polymer gel becomes a limiting factor. A reaction-diffusion model is presented to express the competition between enzyme reaction and diffusion. The scaling theory and kinetic data are used to define the boundaries of the polymer concentration regimes between substrate (i.e., polymer strand) limited reactions, enzyme limited reactions, and hindered diffusion limited reactions. The influence of polymer derivatization on the degradation kinetics was also explored. The degradation rate was shown to be greatly affected by the type of substituent groups as well as the degree of substitution. The triggering mechanism and controlled degradation were found for the enzymatic hydrolysis of cationically derivatized guar solutions.

Identification and quantification of the crystalline structures of poly(vinylidene fluoride) sutures by wide-angle X-ray scattering and differential scanning calorimetry.

The outstanding biocompatibility of the polyvinylidene fluoride (PVDF) monofilament suture together with other desirable characteristics, such as ease of handling and resistance to biodegradation, makes it an attractive alternative monofilament suture material for cardiovascular surgery. However, to achieve a high performance suture, the polymeric raw material must be exposed to different treatments, which lead to different degrees and types of crystallization. Since these crystalline modifications deeply influence the mechanical characteristics and the biostability of the sutures, the authors hereby propose a method of quantifying the different structures of PVDF using wide angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). The commercial devices are achieved by coloring and processing the polymeric raw material. The white and unprocessed 4-0 unswaged suture presents 19% of the alpha phase, 38% of the beta structure, and no gamma form. Coloration increases the amount of the beta phase by 5-9% at the expense of the alpha phase. On the other hand, processing the fibers lead to the conversion of some of the amorphous phase to the gamma structure, the importance of which is 6-7%. Finally, tensile measurements performed on the different PVDF fibers clearly proves that their mechanical characteristics depend on the presence of these crystalline forms in the polymeric structure of PVDF.

Influence of strain and medium composition on filtration of escherichia coli suspensions.

Cross-flow filtration of Escherichia coli strains was examined at the laboratory and pilot scales using Romicon 500,000 molecular-weight-cutoff hollow fiber membranes. Both the series resistance and macrosolute polarization models were employed to compare performances. Total dissolved solids content above 90 g/L and viscosity above 1.1 x 10(-3) pac s of cell-free culture media were found to decrease average filtration fluxes by over 60% both in the absence and presence of cells. Broth filtration with culture media of dissolved solids levels below 80 g/L were influenced to a greater extent by harvest cell density. The collodial nature of the complex nutrient responsible for the total solids increase affected prediction of filtration performance. Differences in strain filterability were observed with JM109 preferred over DH5 in high solids-containing media and RR1 preferred over JM109 in low dissolved solids-containing media. Their research demonstrates the importance of cell strain and media selection in the performance of early downstream processing steps. (c) 1994 John Wiley & Sons, Inc.

Molecular weight characterization of virgin and explanted polyester arterial prostheses.

The macromolecular properties of 17 virgin commercial arterial prostheses and a series of explanted prostheses, both manufactured from poly(ethylene terephthalate) (PET) yarns, have been studied by gel permeation chromatography (GPC) and by differential scanning calorimetry (DSC). Only small differences were found between the average molecular weights and the degree of crystallinity of the unused reference grafts. A broadening of the DSC curves was observed for the prostheses containing texturized yarns compared with those made solely from flat, untexturized yarns. This broadening may be due to greater heterogeneity of the crystal sizes caused by the texturizing process and to the use of two or more different yarns with dissimilar thermal histories in the same prosthesis. Average molecular weights of the explant series were significantly lower than those of the corresponding reference grafts but almost time independent. The polydispersity index and the degree of crystallinity of the explants remained constant as a function of time. These results are discussed in regard to others available in the literature.

Calorimetric study of water in muscle tissue.

Differential scanning calorimetry has been used to investigate the state of water in intact single muscle fibers of the giant barnacle, Balanus nubilus. The shapes of the melting curves suggest the presence of three types of water: unfrozen (or bound), free (or bulk) and intermediate water. The amount of unfrozen water per g protein was constant within experimental error. An increase in water content changed almost exclusively the amounts of free water. The amount of intermediate water varies only slightly with the fiber water content.