Computerizing ICBF Method for Schedule Delay Analysis

Schedule delay is a common construction dispute. For analyzing schedule delays, a previous study had proposed an academic analysis method, the “isolated collapsed but-for” (ICBF) method. However, because many construction projects involve numerous complex activities, the procedure of using the ICBF method for schedule delay analysis is time-consuming. Therefore, this study used Microsoft Visual Basic for Applications (VBA) language and spreadsheet techniques to develop an Excel-based program for rapid delay analysis rather than manual calculation. A case study confirmed that the program automatically produces analytical results with only common delay documents (as-planned and as-built schedules and identified delay events). Compared with previous studies, schedule analysts can obtain analysis results quickly and correctly. Research results provide not only a convenient tool for schedule delay analysis but also a guide to computerize various academic delay analysis methods in the future.     

Occurrence of histamine and histamine-forming bacteria in kimchi products in Taiwan

Twenty kimchi products sold in supermarkets and 17 products sold in retail markets were purchased from southern Taiwan and tested to determine the occurrence of histamine and histamine-forming bacteria. The levels of pH and salt content in all samples ranged from 3.6 to 5.1 and 1.5–16.0%, respectively. The supermarket kimchi products had 1–7.2 log CFU/g of APC and <3–600 MPN/g of total coliform (TC), and the retail market kimchi products had 4–8.03 log CFU/g of APC and <3 to >2400 MPN/g of TC. Only one of the retail market kimchi products contained 20 MPN/g Escherichia coli. Although, supermarket kimchi products had an average histamine content of 49.8 mg/100 g, 15 of them had histamine content greater than 5 mg/100 g, the allowable level set by the US Food and Drug Administration (FDA) for scombroid fish and/or product. In contrast, only eight retail market kimchi products had histamine levels greater than 5 mg/100 g. Among the supermarket samples, three contained histamine at 50.2, 273 and 535 mg/100 g, that are more than the 50 mg/100 g hazard action level. Four histamine-producing bacteria capable of producing 13.6–43.1 ppm of histamine in MRS broth supplemented with 0.25% l-histidine were identified as Lactobacillus para. paracasei (one strain), Lb. brevis (one strain), and Brevibacillus brevis (two strains). To our knowledge, this is the first report to demonstrate the occurrence of high contents of histamine and histamine-forming bacteria in kimchi products.     

Improved agar diffusion method for detecting residual antimicrobial agents

The improved agar diffusion method for determination of residual antimicrobial agents was investigated, and the sensitivities of various combinations of test organisms and assay media were determined using 7 organisms, 5 media, and 31 antimicrobial agents. Bacillus stearothermophilus and synthetic assay medium (SAM) showed the greatest sensitivity for screening penicillins (penicillin G and ampicillin). The combination of Bacillus subtilis and minimum medium (MM) was the most sensitive for tetracyclines (oxytetracycline and chlortetracycline), B. stearothermophilus and SAM or Micrococcus luteus and Mueller-Hinton agar (MHA) for detecting tylosin and erythromycin, B. subtilis and MHA for aminoglycosides (streptomycin, kanamycin, gentamicin, and dihydrostreptomycin), B. stearothermophilus and SAM for polyethers (salinomycin and lasalocid), and B. subtilis and MM or Clostridium perfringens and GAM for polypeptides (thiopeptin, enramycin, virginiamycin, and bacitracin). However, gram-negative bacterium Escherichia coli ATCC 27166 and MM were better for screening for colistin and polymixin-B. For detecting the synthetic drugs tested, the best combination was B. subtilis and MM for sulfonamides, E. coli 27166 and MM for quinolones (oxolinic acid and nalidixic acid), B. subtilis and MM for furans (furazolidone), and the bioluminescent bacterium Photobacterium phosphoreum and luminescence assay medium for chloramphenicol and oxolinic acid. The results showed that the use of four assay plates, B. stearothermophilus and SAM, B. subtilis and MM, M. luteus and MHA, and E. coli 27166 and MM, was superior to the currently available techniques for screening for residual antimicrobial agents in edible animal tissues.     

A reactive modifier that enhances the thermal mechanical properties of epoxy resin through the formation of multiple hydrogen-bonded network

In this study, we synthesized a reactive modifier [DOPO-tris(azetidine-2,4-dione)], terminated with three azetidine-2,4-dione functional groups, from [(9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-yl)tris(4-aminophenyl)methane; DOPO-triamine] and [4-isocyanato-4′-(3,3-dimethyl-2,4-dioxo-acetidino)diphenylmethane; IDD]. We embedded this reactive modifier, which contains multiple hydrogen bond donor and acceptor units, into epoxy resins to promote intermolecular interactions and to tailor its flexibility through the formation of unique pseudo-crosslinked polymer networks. The resulted epoxy resins were found to exhibit glass transition temperature as high as 187 °C and excellent flame retardancy with limited oxygen index (LOI) values around 38. Meanwhile, the dynamic mechanical analysis (DMA) of epoxy systems increases from 0.67 to 2.13 GPa for storage modulus and 0.73–1.67 GPa for loss modulus at 100 °C. Incorporation of reactive modifier into epoxy networks with noncovalent interactions via thermosetting blend was demonstrated to be an effective way to enhance the thermal and physical properties simultaneously.     

Drawing and tensile properties of polyamide 6/calcium chloride composite fibers

The influence of calcium chloride (CaCl₂) contents on the drawing and tensile properties of polyamide 6 (PA6)/CaCl₂ composite fibers prepared at varying drawing temperatures were investigated. At any fixed drawing temperature, the achievable draw ratio (D_ra) values of PA6_x(CaCl₂)_y as-spun fiber specimens approach a maximum value, as their CaCl₂ contents are close to the 3 wt% optimum value. The maximum D_ra values obtained for PA6_x(CaCl₂)_y as-spun fiber specimens prepared at the optimum CaCl₂ content reach another maximum as their drawing temperatures approach the optimum drawing temperature at 120 °C. The initial modulus, tensile strength and birefringence values of the PA6 and PA6_x(CaCl₂)_y fiber specimens were found to improve consistently with D_ra or with drawing temperatures when they were stretched to a fixed D_ra. Similar to those found for their achievable drawing properties, the ultimate initial modulus, tensile strength and birefringence values of PA6_x(CaCl₂)_y fiber specimens approach a maximum value, as their CaCl₂ contents and drawing temperatures approach the 3 wt% and 120 °C optimum values, respectively. Experiments including thermal, FTIR, melt shear viscosity and wide angle X-ray diffraction experiments were performed on the PA6_x(CaCl₂)_y resin and/or fiber specimens to clarify the possible reasons accounting for the interesting drawing, tensile and birefringence properties found for the PA6_x(CaCl₂)_y fiber specimens.     

Bioactive properties and clinical safety of a novel milk protein peptide

Background

Inadequate eating behavior and physical inactivity contribute to the current epidemic of childhood obesity. The aim of this study was to assess the association between eating behavior scores and childhood obesity in Chilean children.

Design and methods

We recruited 126 obese, 44 overweight and 124 normal-weight Chilean children (6-12 years-old; both genders) according to the International Obesity Task Force (IOTF) criteria. Eating behavior scores were calculated using the Child Eating Behavior Questionnaire (CEBQ). Factorial analysis in the culturally-adapted questionnaire for Chilean population was used to confirm the original eight-factor structure of CEBQ. The Cronbach's alpha statistic (>0.7 in most subscales) was used to assess internal consistency. Non-parametric methods were used to assess case-control associations.

Results

Eating behavior scores were strongly associated with childhood obesity in Chilean children. Childhood obesity was directly associated with high scores in the subscales "enjoyment of food" (P < 0.0001), "emotional overeating" (P < 0.001) and "food responsiveness" (P < 0.0001). Food-avoidant subscales "satiety responsiveness" and "slowness in eating" were inversely associated with childhood obesity (P < 0.001). There was a graded relation between the magnitude of these eating behavior scores across groups of normal-weight, overweight and obesity groups.

Conclusion

Our study shows a strong and graded association between specific eating behavior scores and childhood obesity in Chile.     

A novel microfluidic mixer using aperiodic perturbation flows

A novel technique is proposed for enhancing the mixing performance of a ‘crisscross’ microfluidic mixer by means of aperiodically-varying perturbation flows. The effects of the perturbation and geometry parameters on the fluid flow characteristics and mixing performance are analyzed numerically. In performing the simulations, the flow field and species concentration field are obtained by solving the two-dimensional time-dependent Navier–Stokes equations and the convection–diffusion equation, respectively. In addition, the oscillating source used to modulate the perturbation flows is modeled using the Sprott system. The results show that the irregularly-alternating flow perturbations cause a repeated stretching and folding of the species streams and enhance the mixing performance as a result. It is shown that an effective improvement in the mixing performance can be obtained through a suitable choice of the Sprott system scaling factor. Moreover, it is shown that having assigned an appropriate scaling factor, the mixing performance can be further improved by specifying suitable values of the geometry and perturbation parameters.     

A hydrogen peroxide sensor based on a horseradish peroxidase/polyaniline/carboxy-functionalized multiwalled carbon nanotube modified gold electrode

We have developed a polyaniline/carboxy-functionalized multiwalled carbon nanotube (PAn/MWCNTCOOH) nanocomposite by blending the emeraldine base form of polyaniline (PAn) and carboxy-functionalized multiwalled carbon nanotubes (MWCNT) in dried dimethyl sulfoxide (DMSO) at room temperature. The conductivity of the resulting PAn/MWCNTCOOH was 3.6 × 10⁻³ S cm⁻¹, mainly as a result of the protonation of the PAn with the carboxyl group and the radical cations of the MWCNT fragments. Horseradish peroxidase (HRP) was immobilized within the PAn/MWCNTCOOH nanocomposite modified Au (PAn/MWCNTCOOH/Au) electrode to form HRP/PAn/MWCNTCOOH/Au for use as a hydrogen peroxide (H₂O₂) sensor. The adsorption between the negatively charged PAn/MWCNTCOOH nanocomposite and the positively charged HRP resulted in a very good sensitivity to H₂O₂ and an increased electrochemically catalytical current during cyclic voltammetry. The HRP/PAn/MWCNTCOOH/Au electrode exhibited a broad linear response range for H₂O₂ concentrations (86 μM–10 mM). This sensor exhibited good sensitivity (194.9 μA mM⁻¹ cm⁻²), a fast response time (2.9 s), and good reproducibility and stability at an applied potential of −0.35 V. The construction of the enzymatic sensor demonstrated the potential application of PAn/MWCNTCOOH nanocomposites for the detection of H₂O₂ with high performance and excellent stability.     

Self‐assembled and crystallized composites made from poly(ether amine) and montmorillonite in the presence of copper(II) ions

Self‐assembled and crystallized composites made from montmorillonite (MMT) by intercalation with poly(ether amine) salts and copper(II) [Cu(II)] ions simultaneously were studied. The manipulation of the silicate unit structure of the secondary (001) lattice by physically imposed osmotic pressure on the platelet interlayer was used. Divalent copper salt assisted a strong depletion effect with balancing the counterions in the clay interlayer and resulted in the extension of the dimensions of the (001) plane by increasing the spacing expansion by more than two orders of magnitude. The simultaneous adsorption of Cu(II) and intercalation of poly(oxypropylene)amine (POP) salts onto the MMT units ultimately minimized their amorphous aggregation through electrostatic attraction between the negative surface and positive edge among the silicate units. Alternatively, the attraction force through face‐to‐face stacking on the silicate surface is proposed, and the conformation of the POP/Cu(II) complex aligned with the approaching platelets to form orderly structures. X‐ray diffraction of the MMT units exhibited a high order of reflection (i.e., (006)) in Bragg's pattern; this implied a repetitive regularity between the plate–plate distances. The high regularity disappeared when the Cu(II) adsorption exceeded the critical clay cation‐exchange capacity of 1.4. The conformation of the flexible polyether backbone was altered and could no longer sustain the plate distance and the symmetric packing was destroyed when the basal spacing was decreased from 82.6 to 18.0 Å. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011