Lethality calculation for thermal processes with different heating and cooling rates

In many thermal processes, the time constants f_h and f_c for the heating and cooling periods differ. This can cause difficulties in calculating the process lethality. This paper presents a simple method for taking into account this change in the time constant. The author's formula method is tested against simulated data from finite-difference computations, both for f_h=f_c and for f_h≠f_c , and found to be at least as accurate as the best previous formula method.     

Load Bearing Capacity of Reinforced Concrete Beams Subjected to Dynamic Cyclic Loads

A kinematic method is developed to determine the shakedown limits of elastic-perfectly plastic steel-reinforced concrete beams under quasi-static and dynamic cyclic loads. This procedure, like the respective kinematic approach of plastic limit analysis, is visual and easy to use in engineering applications. The load parameters (amplitudes, frequency) versus yield moment diagrams, constructed from possible collapse modes, should assist in choosing the reinforcement scheme and amounts of reinforcement to meet the load bearing requirements for the structures.     

Mechanisms underlying the effects of membrane fouling on the nanofiltration of trace organic contaminants

The influence of membrane fouling on the retention of four trace organic contaminants - namely sulfamethoxazole, ibuprofen, carbamazepine, and triclosan - by nanofiltration membranes was investigated in this study. Humic acid, alginate, bovine serum albumin, and silica colloids were selected as model foulants to simulate various organic fractions and colloidal matter that are found in secondary treated effluent and surface water. The effects of membrane fouling on the separation process was delineated by comparing retention values of clean and fouled membranes and relate them to the membrane properties (under both clean and fouled conditions) as well as physicochemical characteristics of the trace organic contaminants. Membrane fouling was dependent on the physicochemical properties of the model foulants. Initial foulant-membrane interaction could probably be a major factor governing the process of membrane fouling particularly by the organic foulants. Such membrane-foulant interaction was also a dominating factor governing the effects of membrane fouling on the membrane separation efficacy. In good agreement with our previous study (Nghiem and Hawkes, 2007 [1]), the effects of fouling on retention were found to be membrane pore size dependent. In addition, results reported here suggest that these effects could also be foulant dependent. It was probable that the influence of membrane fouling on trace organic retention could be governed by four distinctive mechanisms: modification of the membrane charge surface, pore blocking, cake enhanced concentration polarisation, and modification of the membrane hydrophobicity. The presence of the fouling layer could affect the retention behavior of charged solutes by altering the membrane surface charge density. While the effect of surface charge modification was clear for inorganic salts, it was less obvious for the negatively charged pharmaceutical species (sulfamethoxazole and ibuprofen) examined in this investigation, possibly due to the interference of the pore blocking mechanism. Evidence of the cake enhanced concentration polarisation effect was quite clear, particularly under colloidal fouling conditions. In addition, organic fouling could also interfere with the solute-membrane interaction, and therefore, exerted considerable influence on the separation process of the hydrophobic trace organic contaminant triclosan.     

天然裂缝性储层的特征

天然裂缝性储层给开采带来了一个矛盾难题。这类储层包括低油气采收率储层,这些储层最初可能表现出高产,但产能下降得非常快。此外,这类储层还经常出现早期见气或见水等问题。而另一方面,一些天然裂缝性储层也是全球最大、产量最高的储层。这类储层的这种矛盾特性激发业界尽力去深入了解其特征,以便更有把握地对其进行模拟分析。     

Properties of Anthocyanins from Grape Cell Culture

Color and thermal- and pH-stability of anthocyanins from a grape cell suspension culture were compared with those of commercial food colorants using Hunter and spectrophotometric analysis. At pH 3, grape cell anthocyanins showed color vividness (Chroma) similar to red cabbage and higher than that of other samples and a hue (Theta) similar to purple corn and redder than other samples. Brown oxidized phenolics were absent from the cell culture and red cabbage preparations, but were found in other samples. Color loss during incubation at 30 and 95°C, pH 3 and during an increase in pH from 3 to 5 was more severe for cell culture than red cabbage anthocyanins probably indicating they were intrinsically more sensitive.     

Nebulized Gadolinium‐Based Nanoparticles: A Theranostic Approach for Lung Tumor Imaging and Radiosensitization

Lung cancer is the most common and most fatal cancer worldwide. Thus, improving early diagnosis and therapy is necessary. Previously, gadolinium‐based ultra‐small rigid platforms (USRPs) were developed to serve as multimodal imaging probes and as radiosensitizing agents. In addition, it was demonstrated that USRPs can be detected in the lungs using ultrashort echo‐time magnetic resonance imaging (UTE‐MRI) and fluorescence imaging after intrapulmonary administration in healthy animals. The goal of the present study is to evaluate their theranostic properties in mice with bioluminescent orthotopic lung cancer, after intrapulmonary nebulization or conventional intravenous administration. It is found that lung tumors can be detected non‐invasively using fluorescence tomography or UTE‐MRI after nebulization of USRPs, and this is confirmed by histological analysis of the lung sections. The deposition of USRPs around the tumor nodules is sufficient to generate a radiosensitizing effect when the mice are subjected to a single dose of 10 Gy conventional radiation one day after inhalation (mean survival time of 112 days versus 77 days for irradiated mice without USRPs treatment). No apparent systemic toxicity or induction of inflammation is observed. These results demonstrate the theranostic properties of USRPs for the multimodal detection of lung tumors and improved radiotherapy after nebulization.     

Mechanism of Crystallization and Implications for Charge Transport in Poly(3‐ethylhexylthiophene) Thin Films

In this work, crystallization kinetics and aggregate growth of poly(3‐ethylhexylthiophene) (P3EHT) thin films are studied as a function of film thickness. X‐ray diffraction and optical absorption show that individual aggregates and crystallites grow anisotropically and mostly along only two packing directions: the alkyl stacking and the polymer chain backbone direction. Further, it is also determined that crystallization kinetics is limited by the reorganization of polymer chains and depends strongly on the film thickness and average molecular weight. Time‐dependent, field‐effect hole mobilities in thin films reveal a percolation threshold for both low and high molecular weight P3EHT. Structural analysis reveals that charge percolation requires bridged aggregates separated by a distance of ≈2–3 nm, which is on the order of the polymer persistence length. These results thus highlight the importance of tie molecules and inter‐aggregate distance in supporting charge percolation in semiconducting polymer thin films. The study as a whole also demonstrates that P3EHT is an ideal model system for polythiophenes and should prove to be useful for future investigations into crystallization kinetics.     

选择LDO的方法 便携应用在基本条件之外提出更多要求

在选择低压降线性调节器(LDO)时,需要考虑的基本问题包括输入电压范围、预期输出电压、负载电流范围及其封装的功耗能力.但是,便携式应用通常还需要考虑更多问题,比如接地电流或静态电流(IGND或IQ)、电源波纹抑制比(PSRR)、噪声与封装大小等通常也是为便携式应用决定最佳LDO选择的考虑要素.