Ramsis Farag

N-Halamine modified thermoplastic polyurethane with rechargeable antimicrobial function for food contact surface

A polymer blend of two N-halamine precursors was prepared and homogeneously incorporated into TPU structure via a solvent casting method, and an N-halamine modified TPU film with rechargeable antimicrobial activity resulted after treating with chlorine bleach. Antimicrobial efficacies were evaluated against both Staphylococcus aureus (S. aureus) and Escherichia coli O157:H7 (E. coli). Results showed that the N-halamine modified TPU film caused 6 log CFU reduction of bacteria reduction within 2 hours of contact. Moreover, the N-halamine modified TPU displayed desirable rechargeability and stability, which maintained sufficient antimicrobial activity after 20 cycles of “discharge–recharge” process and over 4 weeks of storage. Besides, the tensile strength and surface tension of TPU were not adversely affected by N-halamine modification. The N-halamine modified TPU with rechargeable antimicrobial function exhibited great potential as a cheap, safe and effective food contact surface material for preventing food microbial cross-contamination.

An Integrated Approach to Analyzing the Nature of Multicomponent Fiber Blending: Part II: Experimental Analysis of Structural and Attributive Blending

In this part of our study, we report the results of an experimental analysis of the structural and attributive blending modes discussed in Part I. This analysis results in a number of interesting findings relevant to the nature of multiple-component fiber blends. In the case of cotton/cotton blends, cotton fibers of substantially different length and fineness values can be blended together, provided that an adjustment is made to yield a proportionally balanced structural blending. The results also indicate that blending cotton fibers with substantially different levels of maturity and elongation may result in an attributive bias toward the fiber component exhibiting poor maturity and low elongation. When cotton and polyester fibers are blended together, there is severe bi-modality in the blended fiber length distribution. This bi-modality can occur even if the blend profile exhibits a linear pattern. When low-strength/high-elongation polyester is blended with high-strength/low-elongation cotton, nonlinear blend profiles of fiber strength and elon gation are produced. In this case, yarn strength and elongation are determined by the low values of fiber strength and elongation. When high-strength/high-elongation polyester fibers are blended with low-strength/low-elongation cotton fibers, linear and additive blend profiles of fiber strength and elongation are produced. In this case, the strength of the blended yarn is biased toward the high-strength component, and the elongation of the blended yarn is biased toward the low-elongation component.

In Vitro Evaluation of the Aberdeen Knot for Continuous Suture Patterns with Large Gauge Suture

OBJECTIVE To evaluate the strength, size, and holding capacity of the Aberdeen knot compared to surgeons and square knots using large gauge suture. STUDY DESIGN In vitro mechanical study. STUDY POPULATION Knotted suture. METHODS Aberdeen, surgeons, and square knots were tested using 2 and 3 USP polyglactin 910 and 2 USP polydioxanone under linear tension on a universal testing machine. Mode of failure and knot holding capacity (KHC) were recorded and relative knot security (RKS) was calculated as a percentage of KHC. Knot volume and weight were quantified by a digital micrometer and balance, respectively. Strength between number of throws, suture, suture size, and knot type were compared by ANOVA and post hoc testing. P≤.05 was considered significant. RESULTS Aberdeen knots had higher KHC and RKS than surgeons or square knots for all suture types and number of throws (P<.001). For all suture materials, none of the Aberdeen knots unraveled, but a portion of square and surgeons knots with <7 throws did unravel (P=.101). Aberdeen knots had a smaller volume and weight than both surgeons and square knots with equal numbers of throws (P<.001). The knot with the combined highest RKS and smallest size and weight was an Aberdeen knot with 4 throws using 3 USP polyglactin 910. CONCLUSION The Aberdeen knots were stronger, more secure, and smaller than surgeons and square knots for ending a continuous suture pattern. Clinically, the Aberdeen knot may be a useful alternative for completion of continuous patterns using large gauge suture, without sacrificing knot integrity.

Effect of fluid media on the mechanical properties of continuous pattern-ending surgeon's, square, and Aberdeen knots in vitro†

OBJECTIVE To investigate the knot holding capacity (KHC) of pattern-ending square, surgeons and Aberdeen knots each tied in 4 throw combinations using large gauge suture after exposure to media commonly found in equine abdominal surgery. STUDY DESIGN In vitro mechanical study. SAMPLE POPULATION Knotted suture strands (n = 10/group). METHODS Strands of 2 polydioxanone or 3 polyglactin 910 were exposed to 1 of 4 media for 15 minutes. Control suture strands remained dry. Media used included balanced electrolyte solution, 1% sodium carboxymethylcellulose, equine serum, or equine fat. Pattern-ending knots for the 3 knot configurations were loaded to failure in a linear fashion on a materials testing machine to determine KHC. RESULTS Surgeons knots tied using media-exposed 3 polyglactin 910 had a significantly higher KHC than the same dry knots with 5 and 6 throws. Square knots tied using media-exposed to 3 polyglactin 910 had a significantly higher KHC than the same dry knots at 5 throws. Aberdeen knots tied with either media-exposed 2 polydioxanone or 3 polyglactin 910 had a significantly higher KHC than their equivalent dry knots. Aberdeen knots had a superior KHC, while requiring less suture than both surgeons and square knots. CONCLUSION Media exposure either had no effect on KHC or significantly improved the KHC of all knots investigated. Based on KHC and knot volume, Aberdeen knots tied using media-exposed 3 polyglactin 910 with 3 throws and 1 turn are recommended to end a continuous suture pattern.

An Integrated Approach to the Analysis of Multi-Component Fiber Blending. Part III: Analysis of Interactive Fiber Blending

This paper represents the third of a three-part series in which multi-component fiber blending was analyzed using an integrated approach. The essence of this approach is that the phenomenon of fiber blending should be viewed on the basis of four basic modes of blending: structural blending, attributive blending, interactive blending, and appearance blending. In this part of the study, the focus is on interactive blending. A modified rotor ring system is used in which the torque associated with opening and blending of a certain mass of fibers is monitored throughout its complete run. Blends of different cotton fiber types and blends of polyester and cotton fibers are evaluated using a number of analytical methods such as the torque profile during opening and blending, the blend profile of torque parameters, and the progressive change resulting from consecutive opening and blending. The results of this study revealed that when cotton fibers of different types are blended together, fiber length and fiber fineness can influence interactive blending in such a way that a great deal of the initial mechanical work done is consumed in opening and blending the longer and finer component in the blend. Large difference in fiber length and fiber fineness can result in a nonadditive and nonlinear maximum torque associated with blending. When cotton fibers are blended with polyester fibers, surface incompatibility becomes a more serious issue than fiber dimensional characteristics. In this regard, a possible failure of fiber cluster breakdown may occur, leading to nonlinear and nonadditive interactive blending. The results also reveal that the propensity to opening of different fiber types may follow different trends in consecutive processing.

Tensile properties of cotton fibers: Importance, research, and limitations

Abstract In this chapter, the focus will be on the tensile behavior of cotton fibers through discussions of six key subjects. The first subject deals with the structural features of cotton fiber, particularly those that are directly related to the tensile behavior of cotton fiber including the degree of crystallinity, the degree of orientation, the convolution effect, and the tapering effect of the fiber. The second subject of this chapter deals with the different methods of static tensile testing. The third subject addresses the stress–strain curve and the different tensile parameters that can be derived from the curve. The fourth subject covers key aspects related to cotton fiber strength testing, including the type of testing (single-fiber strength vs. bundle strength) and the moisture–strength relationship of cotton fibers. The fifth subject addresses the dynamic tensile behavior of cotton fiber with a brief review of the different methods of dynamic testing and the methods of characterizing the dynamic tensile behavior of cotton fibers. The final subject covers the impact of cotton fiber strength on the processing performance of fibers and the durability of end products. Unlike most classic reviews of literature, this chapter represents critical analyses of the progress in research in the area of cotton fiber strength and recommendations for many new research ideas in the field.

In vitro evaluation of square and surgeon's knots in large gauge suture: GILLENet al.

OBJECTIVE To investigate the strength and size of surgeons and square knots for starting and ending continuous suture lines using large gauge suture. STUDY DESIGN In vitro mechanical study. STUDY POPULATION Knotted suture. METHODS Surgeons and square knots were tested using 2 and 3 USP polyglactin 910 and 2 USP polydioxanone under linear tension on a universal testing machine. Failure mode and knot holding capacity (KHC) were recorded, and relative knot security (RKS) was calculated as a percentage of KHC. Comparisons were made between number of throws, suture size, suture type, and knot types. Knot volume and weight were assessed by a digital micrometer and balance, respectively. RESULTS There were no significant differences in KHC (P = .295), RKS (P = .307), volume (P = .128), or weight (P = .310) between square and surgeons knots at the start or end of suture lines with the same number of throws and suture type. A minimum of 6 throws were required for start knots and 7 throws at end knots to prevent unraveling. Knots tied with 3 polyglactin 910 were strongest (P < .001) and 2 polyglactin 910 produced knots with higher KHC and RKS than 2 polydioxanone (P < .001). CONCLUSION No consistent differences were detected between knots types tied with the same suture material; however, number of throws affected KHC and RKS up to 6 throws in start or 7 throws in end knots. The configuration of square and surgeons knots performed at the end of a continuous line alters their KHC, supporting the use of additional throws for knot security.

Tensile Properties Evaluation of Chemically Treated/Untreated Single Sugarcane Fiber

Natural fiber as a reinforcing constituent can play a dominant role in the field of fiber reinforced polymer composites (FRPC) due to its eco-friendliness, renewability, abundance in nature, co2-neutrality, flexibility, low density, and low cost. Hence, sugarcane fiber can be a potential candidate to replace the synthetic FRPC. The objective of this study is to evaluate the effect of chemical treatment on the tensile properties of single sugarcane fiber. Sugarcane collected from the local market was cut into some specific length and fibers were extracted from the juicy section. These fibers were then dried in an oven to remove the moisture. Surface modification was accomplished by performing alkali treatment and neutralizing by acetic acid solution. The fiber was then rinsed with water and dried at 80°C for about twenty four hours using an oven. Untreated and treated fibers were characterized using tensile testing according to the ASTM D 3822-01 standard. Optical microscopy (OM) was employed to measure the diameter of the fiber and scanning electron microscopy (SEM) was used to evaluate the fracture morphology of failed samples. Tensile tests were carried out on the span length of 25 mm of the single fiber. The resultant data showed that maximum improvement in the tensile strength and modulus was observed to be 87% and 29%, respectively, compared to those of untreated ones due to chemical treatments using 5% NaOH solution and 2% acetic acid solution, respectively. Strain to maximum strength was enhanced by about 16% compared to that of the untreated one. A small initial weight loss was observed in the temperature ranging from 25 to 150 °C due to the evaporation of water. However, untreated fiber started to decompose at around 200 °C while treated fiber started to become decomposed at around 250°C. It might be due to the removal of non-cellulosic substances including hemicellulose, lignin, and pectin as a result of the chemical treatment. Fracture morphology of the treated fiber revealed rougher fracture surfaces compared to untreated fiber surfaces. This is an indication of more energy absorption by the treated fibers during the tensile loading.Copyright