Phase I process monitoring: The case of the balanced one-way random effects model

Phase I is crucial for the success of the overall statistical process control (SPC) and monitoring regime. Shewhart-type charts are recommended in this phase because of their broader shift detection ability. In this paper, a Phase I Shewhart-type $\overline{X}$ chart is considered for the balanced random effects (also called a variance components) model. The proposed methodology takes proper account of the effects of parameter estimation and uses the false alarm probability (FAP) metric to design the chart. In the sequel, the corrected (adjusted) charting constants are calculated and tabulated. The constant can be found, on demand, from an accompanying R package. Motivations and illustrations with some real data are provided. Performance of the chart is examined in terms of in-control robustness and detection of nonhomogeneity (out-of-control). The proposed chart is shown to be easily adaptable to more general models, with more variance components and nested factors, and can accommodate various estimators of variance. Thus, it enables a broader Phase I process monitoring strategy, under normality, which can be applied within the ANOVA framework applicable for many DOE models. A summary and some recommendations are provided.     

The application of layered double hydroxide clay (LDH)-poly(lactide-co-glycolic acid) (PLGA) film composites for the controlled release of antibiotics

Many sites of bacterial infection such as in-dwelling catheters and orthopedic surgical sites require local rather than systemic antibiotic administration. However, currently used controlled release vehicles, such as polymeric films, release water-soluble antibiotics too quickly, whereas nonporous bone cement, used in orthopedics, release very little drug. The purpose of this study was to investigate the use of nanoparticulates composed of layered double hydroxide clays to bind various antibiotics and release them in a controlled manner. Mg-Al (carbonate) layered double hydroxides were synthesized and characterized using established methods. These clay particles were suspended in solutions of the antibiotics tetracycline, doxorubicin (DOX), 5-fluorouracil, vancomycin (VAN), sodium fusidate (SF) and antisense oligonucleotides and binding was determined following centrifugation and quantitation of the unbound fraction by UV/Vis absorbance or HPLC analysis. Drug release from layered double hydroxide clay/drug complexes dispersed in polymeric films was measured by incubation in phosphate-buffered saline (pH 7.4) at 37?°C using absorbance or HPLC analysis. Antimicrobial activity of drug released from film composites was determined using zonal inhibition studies against S. epidermidis. All drugs bound to the clay particles to various degrees. Generally, drugs released with a large burst phase of release (except DOX) with little further drug release after 4?days. Dispersion of drug/clay complexes in poly(lactic-co-glycolic acid) films resulted in a reduced burst phase of release and a slow continuous release for many weeks with effective antimicrobial amounts of VAN and SF released at later time points. Layered double hydroxide clays may be useful for controlled release applications at sites requiring long-term antibiotic exposure as they maintain the drug in a non-degraded state and release effective amounts of drug over long time periods. LDH clay/drug complexes are amenable to homogenous dispersion in polymeric films where implant coating may be optimal or required.     

Designing Phase I Shewhart X¯charts: Extended tables and software

Control charts play an important role in Phase I studies, which are conducted to establish process control and generate reference data for parameter estimation and calculation of prospective (Phase II) control limits. Researchers have tabulated the necessary charting constants for the normal theory–based Phase I Shewhart $\overline{X}$ chart for the process mean to achieve a desired nominal false alarm probability given the number of Phase I subgroups, m, up to 15. However, in practice, when parameters are estimated, the currently recommended number of Phase I subgroups is much larger than covered by their tables. Recognizing the need and taking advantage of some recently available software and computing resources, an extension to these tables is provided for m = 3(1)10 , 15(5)30 , 50(25)300 and n = 3 , 5 , 7 , 10. In addition to the tables, an R program is provided to calculate the charting constant, on demand, for user‐given values of nominal false alarm probability, m, and n. An appendix shows the details of how the program should be used.     

Sensor‐based flow pattern detection—gas–liquid–liquid upflow through a vertical pipe

Flow distribution during gas–liquid–liquid upflow through a vertical pipe is investigated. The optical probe technique has been adopted for an objective identification of flow patterns. The probability density function (PDF) analysis of the probe signals has been used to identify the range of existence of the different patterns. Dispersed and slug flow have been identified from the nature of the PDF, which is bimodal for slug flow and unimodal for dispersed flow. The water continuous, oil continuous, and emulsion type flow distributions are distinguished on the basis of the PDF moments. The method is particularly useful at high flow rates where visualization techniques fail. Based on this, a flow pattern detection algorithm has been presented. Two different representations of flow pattern maps have been suggested for gas–liquid–liquid three phase flow. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3362–3375, 2014     

Malathion exposed seeds of Vigna Sinensis

Plasma membrane bound ATPase of Vigna sinensis (L) is activated by Mg⁺² and is further stimulated by monovalent cations like Na⁺/K⁺, at a definite pH and substrate concentration. The true substrate for the enzyme was Mg⁺⁺‐ATP. Ca⁺⁺ cannot replace Mg⁺⁺ so far as the activation of this enzyme is concerned. Activation does not alter much when treated with ouabain. These results support the concept that cation transport at the plasma membrane of root cells of Vigna sinensis (L) is coupled to a cation‐activated ATPase. Malathion (O, O‐dimethyl phosphorodithioate of diethyl mercapto succinate), an organo phosphorus insecticide, activates these enzymes at a concentration of 400 ppm. This increase in activity may be associated with some alteration in the membrane structure, and stimulation by malathion has been found to be of non‐competitive in nature when the divalent and monovalent ions are included in the system.     

A New Distribution‐free Control Chart for Joint Monitoring of Unknown Location and Scale Parameters of Continuous Distributions

While the assumption of normality is required for the validity of most of the available control charts for joint monitoring of unknown location and scale parameters, we propose and study a distribution‐free Shewhart‐type chart based on the Cucconi 1 statistic, called the Shewhart‐Cucconi (SC) chart. We also propose a follow‐up diagnostic procedure useful to determine the type of shift the process may have undergone when the chart signals an out‐of‐control process. Control limits for the SC chart are tabulated for some typical nominal in‐control (IC) average run length (ARL) values; a large sample approximation to the control limit is provided which can be useful in practice. Performance of the SC chart is examined in a simulation study on the basis of the ARL, the standard deviation, the median and some percentiles of the run length distribution. Detailed comparisons with a competing distribution‐free chart, known as the Shewhart‐Lepage chart (see Mukherjee and Chakraborti 2 ) show that the SC chart performs just as well or better. The effect of estimation of parameters on the IC performance of the SC chart is studied by examining the influence of the size of the reference (Phase‐I) sample. A numerical example is given for illustration. Summary and conclusions are offered. Copyright © 2013 John Wiley & Sons, Ltd.     

Design and properties of a series of high‐temperature thermoplastic elastomeric blends from polyamides and functionalized rubbers

A series of high‐temperature thermoplastic elastomers (TPEs) and thermoplastic vulcanisates (TPVs) were successfully developed based on two different types of heat resistant polyamide (PA) (25 parts by weight)—PA‐12 and PA‐6, in combination with three different functionalized rubbers (75 parts by weight) of varying polarity, e.g., maleic anhydride grafted ethylene propylene diene terpolymer (MA‐g‐EPDM), sulphonated ethylene propylene diene terpolymer, and carboxylated acrylonitrile butadiene rubber, by melt mixing method. These rubbers have low level of unsaturation in its backbone, and the plastics showed high melting range. Thus, the developed TPEs and TPVs were expected to be high temperature resistant. Resol type resin was used for dynamic vulcanization to further increase the high temperature properties of these blends. Interestingly, initial degradation temperature of the prepared blends was much higher (421 °C for MA‐g‐EPDM/PA‐12) than the other reported conventional TPEs and TPVs. Fourier transform infrared analysis described the interactive nature of the TPEs and TPVs, which is responsible for their superior properties. The maximum tensile strength with lowest tension set was observed for the carboxylated acrylonitrile butadiene rubber/PA‐12 TPV. Mild increase in mechanical properties without any degradation was observed after recycling. Dynamic mechanical analysis results showed two distinct glass transition temperatures and indicated the biphasic morphology of the blends, as evident from the scanning electron microscopy. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45353.     

Understanding the Shape-Memory Behavior in Ti-(~49 At. Pct) Ni Alloy by Nanoindentation Measurement

The influence of aging treatment on the work-hardening behavior of near-equiatomic NiTi alloy has been studied at the microstructural scale by conducting the instrumented indentation measurement. The maximum shape recovery is achieved at the peak aged condition. The improvement in shape recovery has been attributed to the delayed onset of plasticity. A comparison has been made between the recoverable strain obtained from the tensile experiments and the recovery index parameter determined from the nanoindentation measurements.