Designing Antimicrobial Polymer Coating to Inhibit Pathogenic and Spoilage Microorganisms

Microbial cross-contamination remains an on-going challenge in the food sector despite implemented sanitation programs. Antimicrobial coatings with inherent self-sanitizing properties have been explored to enhance current cleaning practice and support food safety. Prior work has demonstrated successful incorporation of dual antimicrobial characters, cationic polymers and N-halamines, into one coating system. In addition to the rechargeable nature of N-halamines, the coating was reported to exhibit biocidal effects due to the inherently antimicrobial cationic moieties and the chlorinated N-halamines. However, while these polymer coatings were able to retain antimicrobial activity after repeated chlorination, signs of hydrolysis was observed for the N-halamine bonds, indicating potential issues for long-term usage. Herein, we introduced varied molecular weight cross-linkers in an adaption of the established fabrication method to evaluate cross-linker molecular weight (styrene maleic anhydride (SMA) of 6, 8, 120, 250 kDa) influence on surface properties of the coating. All antimicrobial polymer coatings exhibited similar FTIR spectra, with a prominent absorption band at ~1650 cm-1 suggesting successful cross-link of the polyethyleneimine and SMA. Surface concentration of primary amines ranged from 350-900 nmol/cm2, and N-halamines from 90-130 nmol/cm2. Surface energy decreased with increasing molecular weight of SMA, but were not statistically different from one another. In the end, optimal cross-linker molecular weight was determined based on antimicrobial performance, where the coated PPs with 6 kDa SMAs demonstrated enhanced biocidal effects against E. coli O157:H7 in its chlorinated form. Further, the antimicrobial coating demonstrated efficacy of ~3 to \u3e5 log reductions of microbial load in its unchlorinated and chlorinated form against E. coli O157:H7, L. monocytogenes, and P. fluorescens. Storage studies support the stability of the chlorinated halamines, with full retention of chlorinated N-halamines over a 24 h study (representative of time between sanitation cycles). These results support the potential application of this antimicrobial polymer coating in food processing and handling operations, in support of reducing cross-contamination of spoilage and pathogenic microorganisms

Adaptive RF Pigtail Probe Modeling for De-embedding of RF Measurements

This disclosure describes techniques for accurate estimation and de-embedding of the effects of pigtail probes in circuits. An adaptive pigtail model is developed and described that can accurately de-embed the effects of pigtail probes in digital circuits. Example parameters are identified that include pigtail length, tip length, pigtail tilt degree, ground distance, and solder amount. A pigtail simulation model is developed to model the soldered pigtail probe. The dependency of circuit impedance on the identified parameters is determined by experimentation which indicates that circuit performance can be boosted by short ground distance lengths, low tilt angles, thick support wires, short pin and cable lengths, and thick support wires. The pigtail model can be utilized to derive de-embedded results for different pigtail probe configurations without a need for explicitly measuring de-embedded results for those configurations

Kruskal--Katona-Type Problems via Entropy Method

In this paper, we investigate several extremal combinatorics problems that ask for the maximum number of copies of a fixed subgraph given the number of edges. We call this type of problems Kruskal--Katona-type problems. Most of the problems that will be discussed in this paper are related to the joints problem. There are two main results in this paper. First, we prove that, in a $3$-colored graph with $R$ red, $G$ green, $B$ blue edges, the number of rainbow triangles is at most $\sqrt{2RGB}$, which is sharp. Second, we give a generalization of the Kruskal--Katona theorem that implies many other previous generalizations. Both arguments use the entropy method, and the main innovation lies in a more clever argument that improves bounds given by Shearer's inequality.Comment: 18 page

Tight Bound and Structural Theorem for Joints

A joint of a set of lines $\mathcal{L}$ in $\mathbb{F}^d$ is a point that is contained in $d$ lines with linearly independent directions. The joints problem asks for the maximum number of joints that are formed by $L$ lines. Guth and Katz showed that the number of joints is at most $O(L^{3/2})$ in $\mathbb{R}^3$ using polynomial method. This upper bound is met by the construction given by taking the joints and the lines to be all the $d$-wise intersections and all the $(d-1)$-wise intersections of $M$ hyperplanes in general position. Furthermore, this construction is conjectured to be optimal. In this paper, we verify the conjecture and show that this is the only optimal construction by using a more sophisticated polynomial method argument. This is the first tight bound and structural theorem obtained using this method. We also give a new definition of multiplicity that strengthens the main result of a previous work by Tidor, Zhao and the second author. Lastly, we include some discussion on the constants for the joints of varieties problem.Comment: 39 page

Website quality factors influencing online shopping : a South African perspective

Since the development of the Internet, the amount of individuals and organisations making use of the World Wide Web (or Web) has grown significantly, and it is likely to continue increasing as the world continues to become intertwined. With the Internet, users are able to conduct various activities online, one being online shopping which has changed the retailing sector. Online shoppers are able to purchase goods and services over the Web in the comfort of their own homes without having to set foot into a physical store. Due to the fact that greater numbers of South African consumers are becoming accustomed to online shopping and the number of online retailers is growing, there is a need to determine which quality factors of websites influence these consumers when shopping online, which is the primary purpose of this study. A broad and in-depth literature review was provided on online shopping as well as the website quality factors influencing online shopping. An empirical study was conducted, where the data were collected from South Africans who met the requirements by means of an Internet-based self-administered questionnaire. The study followed a quantitative approach in order to satisfy the research objectives of the study. Based on the research results, it was found that all system, information and service quality factors influence respondents when shopping online and therefore need to be taken into consideration by online retailers when developing shopping sites.Business ManagementM. Com. (Business Management

Digital entrepreneurship

As more companies start doing digital business - whether by selling their products online, by selling digital wares, or both - the question of how starting a digital venture differs from starting a traditional venture grows more important. We present a framework of digital entrepreneurship that includes a topology of new digital ventures, the characteristics of each type of new digital venture, and a discussion of how those characteristics shape the critical success factors of each type of venture. Specific issues addressed include digital or virtual products and services, digital or virtual workplaces and the effects of relying on computer-mediated communication, the changing role of market orientation across the different types of new ventures, and the instant globalization effect

Trust in Virtual Teams: Towards an Integrative Model of Trust Formation

Traditional models of trust have seen trust as being created as a result of a long history of interaction, but recent studies of trust in virtual teams have shown the existence of high initial trust among team members. This paper proposes an integrated model of trust that encompasses both the traditional view of trust and the swift trust found in virtual teams. Based on the dual process theories of cognition, we argue that individuals form trust attitudes via three distinct routes at different stages of a relationship: the peripheral route, the central route, and the habitual route, irrespective. In the initial stages of a relationship when individuals lack information about each other, they rely on peripheral cues (e.g., third party information, social categories, roles, and rules) to form trust. Once individuals have shared history and knowledge of the other party, they use the central route, which involves the assessment of the other party’s ability, integrity, and benevolence. Finally, after long periods of shared history in which the individuals develop a habitual pattern of trust, along with possible emotional bonds, they are no longer motivated to deliberately assess trust, and instead simply enact prior trust attitudes via the habitual route. The mediated communication environment predominantly used by virtual teams slows down the progression among the three routes, and increases perceived risk.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/116290/1/Hung et al. 2004.pd

From Isovist to Spatial Perception: Wayfinding in Historic Quarter

Based on the assumption that human behaviours are mainly affected by physical and animate environments, this empirical research takes the changeful and complex historical district in Tainan to observe wayfinding behaviours. An a priori analysis of the isovist fields is conducted to identify spatial characteristics. Three measures, the relative area, convexity, and circularity, are applied to scrutinize the possible stopping points, change of speed, and route choices. Accordingly, an experiment is carried out to observe spatial behaviours and different influences of social stimuli. Results show that social interactions afford groups and pairs to perform better than individual observers in wayfinding.© 2016. The Authors. Published for AMER ABRA by e-International Publishing House, Ltd., UK. This is an open access article under the CC BY-NC-ND license (http://creative commons.org/licenses/by-nc-nd/4.0/).Peer–review under responsibility of AMER (Association of Malaysian Environment-Behaviour Researchers), ABRA (Association of Behavioural Researchers on Asians) and cE-Bs (Centre for Environment-Behaviour Studies), Faculty of Architecture, Planning & Surveying, Universiti Teknologi MARA, Malaysia.Keywords: wayfinding; isovist; spatial perception and social stimuli; historic quarte