Synchronization,cross-docking,and decoupling in supply chain networks

At any distribution centre (DC), the decision of whether to synchronise inbound and outbound flows for cross-docking, or to decouple these flows by maintaining inventory, has a significant impact on supply chain performance. Key drivers of this decision, in turn, are the sizes of the discrete lots that comprise the flows. Thus, we formulate an original optimisation model that determines order lot-sizing decisions to minimise, for given constant arc flows, the sum of ordering cost and pipeline inventory cost on arcs and buffer inventory at DCs. The model employs an average throughput as a surrogate to estimate buffer inventory at facilities at which synchronisation is not economical and therefore serves to decouple inbound and outbound flows. Perfect lot-for-lot matching of shipments would impose very restrictive constraints on supply chain operations, but equality of average throughput indicates an innovative, relaxed mode of synchronisation. This mode is practicable for cross-docking by means of bulk-breaking or consolidation of shipments. A heuristic approach based on the Lagrangian relaxation and subgradient optimisation is developed for the non-linear mixed-general integer optimisation model, which is illustrated by numerical examples and tested using a benchmark data set.     

Initial synthesis and characterization of an alpha7 nicotinic receptor cellular membrane affinity chromatography column: effect of receptor subtype and cell type

In this study, cellular membrane fragments from SH-EP1-pCEP4-halpha7 and alpha7 HEK-293 cell lines were used to synthesize cellular membrane affinity chromatography (CMAC) columns containing functional alpha7 nicotinic acetylcholine receptors, CMAC(alpha7 nAChR) columns. The synthesis of stable columns required the addition of cholesterol to the 2% cholate solubilization/immobilization (s/i) buffer and to the mobile phase. In addition, when membranes from the SH-EP1 cell line were used, l-alpha-phosphatidylserine and l-alpha-phosphatidylethanolamine also had to be added to the s/i buffer. A CMAC(alpha4beta2 nAChR) column was prepared using membrane fragments from a SH-EP1-pCEP4-halpha4beta2 cell line, and this process required the addition of l-alpha-phosphatidylserine and l-alpha-phosphatidylethanolamine to the s/i buffer, but not cholesterol. The s/i buffers from the three columns were compared with the s/i buffer utilized in the preparation of a CMAC(alpha4beta2 nAChR) column prepared using an alpha4beta2 HEK-293 cell line, which required no additions to the 2% cholate s/i buffer. The data demonstrate that both cell type and receptor type affect the protocol required to produce a stable CMAC column and that, at the current time, the development of an optimum immobilization protocol is an empirical process. The results are also consistent with the observation that the alpha7 nAChR is localized in lipid rafts in both of these cell lines and that the cholate detergent removed cholesterol from these microdomains.     

Rate-dependent frictional adhesion in natural and synthetic gecko setae

Geckos owe their remarkable stickiness to millions of dry, hard setae on their toes. In this study, we discovered that gecko setae stick more strongly the faster they slide, and do not wear out after 30 000 cycles. This is surprising because friction between dry, hard, macroscopic materials typically decreases at the onset of sliding, and as velocity increases, friction continues to decrease because of a reduction in the number of interfacial contacts, due in part to wear. Gecko setae did not exhibit the decrease in adhesion or friction characteristic of a transition from static to kinetic contact mechanics. Instead, friction and adhesion forces increased at the onset of sliding and continued to increase with shear speed from 500 nm s⁻¹ to 158 mm s⁻¹. To explain how apparently fluid-like, wear-free dynamic friction and adhesion occur macroscopically in a dry, hard solid, we proposed a model based on a population of nanoscopic stick–slip events. In the model, contact elements are either in static contact or in the process of slipping to a new static contact. If stick–slip events are uncorrelated, the model further predicted that contact forces should increase to a critical velocity (V*) and then decrease at velocities greater than V*. We hypothesized that, like natural gecko setae, but unlike any conventional adhesive, gecko-like synthetic adhesives (GSAs) could adhere while sliding. To test the generality of our results and the validity of our model, we fabricated a GSA using a hard silicone polymer. While sliding, the GSA exhibited steady-state adhesion and velocity dependence similar to that of gecko setae. Observations at the interface indicated that macroscopically smooth sliding of the GSA emerged from randomly occurring stick–slip events in the population of flexible fibrils, confirming our model predictions.     

THE EFFECT OF INTERPHASE CURING ON INTERPHASE PROPERTIES AND FORMATION

Fiber-optic evanescent wave FTIR spectroscopy was combined with phase imaging AFM to examine two thermosetting polymer matrix composite systems. The epoxy/NMA system data from the fiber-optic, evanescent wave FTIR analysis showed incomplete curing (∼75% complete) in the region near the fiber, but essentially complete (∼95% complete) curing in the bulk. Conversely, the unsaturated polyester system exhibited essentially complete curing (∼95% complete) both near the fiber and in the bulk material. For the same samples, phase imaging AFM indicated that the epoxy/NMA system had an ∼2.5 micron thick interphase, while the unsaturated polyester system showed no interphase between the fiber and the matrix. Therefore, the presence of the interphase in the epoxy/NMA system can be attributed to the incomplete curing next to the fiber. In addition, the systems chosen allowed the reactivity of adsorbed γ-APS coupling agent to be assessed simultaneously with polymer curing. For the epoxy/NMA system, the amine band decreased about 54% during curing. For the polyester system, the amine band decreased 43% during curing.     

Expanding the scope of clinical practice: The physical examination.

Five clinical health psychologists at a major medical center successfully completed a 36-hr, graduate-level nurse practitioner course in advanced health assessment. The psychologists were trained to conduct thorough physical examinations and evaluate medical histories. All psychologists successfully completed the course and reported high levels of comfort with their ability to (a) conduct physical examinations, (b) describe physical examination findings, (c) provisionally identify medical problems and generally abnormal conditions, and (d) make appropriate referrals to medical specialists, when necessary. The nurse practitioner instructors reported high levels of satisfaction with student mastery of course content. The psychologists and nurses both reported high levels of satisfaction with the student–faculty relationship. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Security printing of covert quick response codes using upconverting nanoparticle inks

Counterfeiting costs governments and private industries billions of dollars annually due to loss of value in currency and other printed items. This research involves using lanthanide doped β-NaYF(4) nanoparticles for security printing applications. Inks comprised of Yb(3+)/Er(3+) and Yb(3+)/Tm(3+) doped β-NaYF(4) nanoparticles with oleic acid as the capping agent in toluene and methyl benzoate with poly(methyl methacrylate) (PMMA) as the binding agent were used to print quick response (QR) codes. The QR codes were made using an AutoCAD file and printed with Optomec direct-write aerosol jetting(?). The printed QR codes are invisible under ambient lighting conditions, but are readable using a near-IR laser, and were successfully scanned using a smart phone. This research demonstrates that QR codes, which have been used primarily for information sharing applications, can also be used for security purposes. Higher levels of security were achieved by printing both green and blue upconverting inks, based on combinations of Er(3+)/Yb(3+) and Tm(3+)/Yb(3+), respectively, in a single QR code. The near-infrared (NIR)-to-visible upconversion luminescence properties of the two-ink QR codes were analyzed, including the influence of NIR excitation power density on perceived color, in term of the CIE 1931 chromaticity index. It was also shown that this security ink can be optimized for line width, thickness and stability on different substrates.     

Patterned direct-write and screen-printing of NIR-to-visible upconverting inks for security applications

Two methods of direct-write printing for producing highly resolved features of a polymer impregnated with luminescent upconversion phosphors for security applications are presented. The printed polymer structures range in shape from features to text. The thin polymer features were deposited by direct-write printing of atomized material as well as by screen-printing techniques. These films contain highly luminescent lanthanide-doped, rare-earth nanocrystals, β-NaYF?:3%Er, 17%Yb, which are capped with oleic acid. This capping agent allows the nanocrystals to disperse throughout the films for full detailing of printed features. Upconversion of deposited features was obtained using a 980 nm wavelength laser with emission of upconverted light in the visible region at both 540 and 660 nm. Features were deposited onto high bond paper, Kapton?, and glass to demonstrate possible covert and forensic security printing applications, as they are printed in various features and invisible to 'naked-eye' viewing at low concentrations of nanocrystals.     

The effect of interphase curing on interphase properties and formation

Fiber-optic evanescent wave FTIR spectroscopy was combined with phase imaging AFM to examine two thermosetting polymer matrix composite systems. The epoxy/NMA system data from the fiber-optic, evanescent wave FTIR analysis showed incomplete curing (～75% complete) in the region near the fiber, but essentially complete (～95% complete) curing in the bulk. Conversely, the unsaturated polyester system exhibited essentially complete curing (～95% complete) both near the fiber and in the bulk material. For the same samples, phase imaging AFM indicated that the epoxy/NMA system had an ～2.5 micron thick interphase, while the unsaturated polyester system showed no interphase between the fiber and the matrix. Therefore, the presence of the interphase in the epoxy/NMA system can be attributed to the incomplete curing next to the fiber. In addition, the systems chosen allowed the reactivity of adsorbed γ-APS coupling agent to be assessed simultaneously with polymer curing. For the epoxy/NMA system, the amine band decreased about 54% during curing. For the polyester system, the amine band decreased 43% during curing.     

Using job-shop scheduling tasks for evaluating collocated collaboration

Researchers have begun to explore tools that allow multiple users to collaborate across multiple devices in collocated environments. These tools often allow users to simultaneously place and interact with information on shared displays. Unfortunately, there is a lack of experimental tasks to evaluate the effectiveness of these tools for information coordination in such scenarios. In this article, we introduce job-shop scheduling as a task that could be used to evaluate systems and interactions within computer-supported collaboration environments. We describe properties that make the task useful, as well as evaluation measures that may be used. We also present two experiments as case studies to illustrate the breadth of scenarios in which this task may be applied. The first experiment shows the differences when users interact with different communicative gesturing schemes, while the second demonstrates the benefits of shared visual information on large displays. We close by discussing the general applicability of the tasks.