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1.
M. R. Thompson 《Drug development and industrial pharmacy》2015,41(8):1223-1231
Twin screw granulation (TSG) is a new process of interest to the pharmaceutical community that can continuously wet granulate powders, doing so at lower liquid concentrations and with better product consistency than found by a high shear batch mixer. A considerable body of research has evolved over the short time since this process was introduced but generally with little comparison of results. A certain degree of confidence has been developed through these studies related to how process variables and many attributes of machinery configuration will affect granulation but some major challenges still lay ahead related to scalability, variations in the processing regimes related to degree of channel fill and the impact of wetting and granulation of complex powder formulations. This review examines the current literature for wet granulation processes studied in twin screw extrusion machinery, summarizing the influences of operational and system parameters affecting granule properties as well as strives to provide some practical observations to newly interested users of the technique. 相似文献
2.
3.
M. J. O’Sullivan C. G. Walker M. L. O’Sullivan T. D. Thompson A. B. Philpott 《Telecommunication Systems》2006,33(4):353-376
The problem of designing fibre-optic networks for local-access telecommunications generates (at least) three non-trivial subproblems.
In the first of these subproblems one must determine how many fibre-optic cables (fibres) are required at either end of a
street. In the next subproblem a minimum-cost network must be designed to support the fibres. The network must also provide
distinct paths from either end of the street to the central exchange(s). Finally, the fibre-optic cables must be placed in
protective covers. These covers are available in a number of different sizes, allowing some flexibility when covering each
section of the network. In this paper we describe a dynamic programming (DP) formulation for finding a minimum-cost (protective)
covering for the network (the third of the subproblems). This problem is a generalised set covering problem with side constraints
and is further complicated by the introduction of fixed and variable welding costs. The DP formulation selects covers along
each arc (in the network), but cannot exactly model the fixed costs and so does not guarantee optimality. We also describe
an integer programming (IP) formulation for assessing the quality of the DP solutions. The cost of the networks constructed
by the IP model is less than those designed using the DP model, but the saving is not significant for the problems examined
(less than 0.1%). This indicates that the DP model will generally give very good solutions. Furthermore, as the problem dimensions
grow, DP gives significantly better solution times than IP. 相似文献
4.
B. Ma P.I. Djurovich S. Garon B. Alleyne M.E. Thompson 《Advanced functional materials》2006,16(18):2438-2446
Efficient blue‐, green‐, and red‐light‐emitting organic diodes are fabricated using binuclear platinum complexes as phosphorescent dopants. The series of complexes used here have pyrazolate bridging ligands and the general formula C∧NPt(μ‐pz)2PtC∧N (where C∧N = 2‐(4′,6′‐difluorophenyl)pyridinato‐N,C2′, pz = pyrazole ( 1 ), 3‐methyl‐5‐tert‐butylpyrazole ( 2 ), and 3,5‐bis(tert‐butyl)pyrazole ( 3 )). The Pt–Pt distance in the complexes, which decreases in the order 1 > 2 > 3 , solely determines the electroluminescence color of the organic light‐emitting diodes (OLEDs). Blue OLEDs fabricated using 8 % 1 doped into a 3,5‐bis(N‐carbazolyl)benzene (mCP) host have a quantum efficiency of 4.3 % at 120 Cd m–2, a brightness of 3900 Cd m–2 at 12 V, and Commission Internationale de L'Eclairage (CIE) coordinates of (0.11, 0.24). Green and red OLEDs fabricated with 2 and 3 , respectively, also give high quantum efficiencies (~ 6.7 %), with CIE coordinates of (0.31, 0.63) and (0.59, 0.46), respectively. The current‐density–voltage characteristics of devices made using dopants 2 and 3 indicate that hole trapping is enhanced by short Pt–Pt distances (< 3.1 Å). Blue electrophosphorescence is achieved by taking advantage of the binuclear molecular geometry in order to suppress dopant intermolecular interactions. No evidence of low‐energy emission from aggregate states is observed in OLEDs made with 50 % 1 doped into mCP. OLEDs made using 100 % 1 as an emissive layer display red luminescence, which is believed to originate from distorted complexes with compressed Pt–Pt separations located in defect sites within the neat film. White OLEDs are fabricated using 1 and 3 in three different device architectures, either with one or two dopants in dual emissive layers or both dopants in a single emissive layer. All the white OLEDs have high quantum efficiency (~ 5 %) and brightness (~ 600 Cd m–2 at 10 V). 相似文献
5.
Hyungtak Kim Thompson R.M. Tilak V. Prunty T.R. Shealy J.R. Eastman L.F. 《Electron Device Letters, IEEE》2003,24(7):421-423
The authors report on the effects of silicon nitride (SiN) surface passivation and high-electric field stress (hot electron stress) on the degradation of undoped AlGaN-GaN power HFETs. Stressed devices demonstrated a decrease in the drain current and maximum transconductance and an increase in the parasitic drain series resistance, gate leakage, and subthreshold current. The unpassivated devices showed more significant degradation than SiN passivated devices. Gate lag phenomenon was observed from unpassivated devices and removed by SiN passivation. However, SiN passivated devices also showed gate lag phenomena after high-electric field stress, which suggests possible changes in surface trap profiles occurred during high-electric field stress test. 相似文献
6.
Life is pleasant--and memory helps to keep it that way! 总被引:1,自引:0,他引:1
Walker W. Richard; Skowronski John J.; Thompson Charles P. 《Canadian Metallurgical Quarterly》2003,7(2):203
People's recollections of the past are often positively biased. This bias has 2 causes. The 1st cause lies in people's perceptions of events. The authors review the results of several studies and present several new comparative analyses of these studies, all of which indicate that people perceive events in their lives to more often be pleasant than unpleasant. A 2nd cause is the fading affect bias: The affect associated with unpleasant events fades faster than the affect associated with pleasant events. The authors review the results of several studies documenting this bias and present evidence indicating that dysphoria (mild depression) disrupts such bias. Taken together, this evidence suggests that autobiographical memory represents an important exception to the theoretical claim that bad is stronger than good. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
TC Cope AJ Sokoloff SM Dacko R Huot E Feingold 《Canadian Metallurgical Quarterly》1997,78(6):3077-3082
To further test the hypothesis that some fixed property of motoneurons determines their recruitment order, we quantified the variation in force threshold (FT) for motoneurons recruited in muscle stretch reflexes in the decerebrate cat. Motor axons supplying the medial gastrocnemius (MG) muscle were penetrated with micropipettes and physiological properties of the motoneuron and its muscle fibers, i.e., the motor unit, were measured. FT, defined as the amount of MG force produced when the isolated motor unit was recruited, was measured from 20 to 93 consecutive stretch trials for 29 motor units. Trials were selected for limited variation in base force and rate of rise of force, which have been shown to covary with FT, and in peak stretch force, which gives some index of motor-pool excitability. Under these restricted conditions, large variation in FT would have been inconsistent with the hypothesis. Analysis of the variation in FT employed the coefficient of variation (CV), because of the tendency for FT variance and mean to increase together. We found that CV was distributed with a median value of 10% and with only 2 of 29 units exceeding 36%. Some of this variation was associated with measurement error and with intertrial fluctuations in base, peak, and the rate of change of muscle force. CV was not significantly correlated with motor-unit axonal conduction velocity, contraction time, or force. In three cases FT was measured simultaneously from two motor units in the same stretch trials. Changes in recruitment order were rarely observed (5 of 121 stretch trials), even when FT ranges for units in a pair overlapped. We suggest that the large variation in recruitment threshold observed in some earlier studies resulted not from wide variation in the recruitment ranking of motoneurons within one muscle, but rather from variation in the relative activity of different pools of motoneurons. Our findings are consistent with the hypothesis that recruitment order is determined by some fixed property of alpha-motoneurons and/or by some unvarying combination of presynaptic inputs that fluctuate in parallel. 相似文献
8.
In summary, recent literature indicates that the complications of chronic otitis media have been decreasing. However, even with the advent of modern and more powerful antimicrobials and aggressive surgical eradication of disease, the morbidity and mortality are still high. Some complications may initially be quite obvious and some complications may be quite subtle. Therefore, the most important tools in making early diagnosis are careful history and physical examination, and a high index of suspicion for impending complications. 相似文献
9.
The paper presents the findings of a survey that investigated the level of quality management practice within some 150 UK companies from a sample of 500. It provides a snapshot of practice at the time of the survey, and assesses the impact of government quality initiatives particularly, the TickIT scheme at that time. The survey methodology is described, together with the results and conclusions. The sample has been graded by size of company, which the authors consider to have a significant effect upon the adoption of quality practices. The survey highlights the need to encourage small companies to adopt quality practices and to assist them with the short-term costs incurred. 相似文献
10.