二次风喷射角度对切向燃烧炉膛出口烟气流量偏差的影响

针对四角切向燃烧大容量锅炉普通存在的由于烟气残余旋转造成的上炉膛及对流烟道中的烟气流量左右两侧偏差问题进行了分析研究。并以一台４１０ｔ／ｈ锅炉为对象,用数值模拟方法,在原有设计方案基础上,改变某些流动参数,如不同的二次风喷射角度、最上层二次风反切流动,在计算机上进行模拟计算,分析总 模拟结果进而提出降低炉膛出口烟气速度偏差的可行方案。     

Identification and Quantification of Volatile Chemical Spoilage Indexes Associated with Bacterial Growth Dynamics in Aerobically Stored Chicken

Volatile organic compounds (VOCs) as chemical spoilage indexes (CSIs) of raw chicken breast stored aerobically at 4, 10, and 21 °C were identified and quantified using solid phase microextraction (SPME) combined with gas chromatography‐mass spectrometry (GC‐MS). The growth dynamics of total viable count (TVC), psychrotrophs, Pseudomonas spp., lactic acid bacteria (LAB), Brochothrix thermosphacta and H₂S producing bacteria were characterized based on maximum growth rates (μ_max), maximal microbial concentration (N_max) and at the moment of microbial shelf life (S_values), calculated from Gompertz‐fitted growth curves. Pseudomonas spp. was predominant species, while B. thermosphacta was characterized by the highest μ_max. The microbiological and sensory shelf lives were estimated based on TVC, Pseudomonas spp., and B. thermosphacta counts and sensory evaluation, respectively. Among 27 VOCs identified by GC‐MS in spoiled chicken samples, ethanol (EtOH), 1‐butanol‐3‐methyl (1But‐3M), and acetic acid (C₂) achieved the highest Pearson's correlation coefficients of 0.66, 0.61, and 0.59, respectively, with TVC, regardless of storage temperature. Partial least squares (PLS) regression revealed that the synthesis of 1But‐3M and C₂ was most likely induced by the metabolic activity of B. thermosphacta and LAB, while EtOH was attributed to Pseudomonas spp. The increase in concentration of selected volatile spoilage markers (EtOH, 1But‐3M, and C₂) in the headspace over spoiled chicken breast was found to be statistically significant (P < 0.05) with TVC growth. These findings highlight the possibility of analyzing the combination of 3 selected spoilage markers: EtOH, 1But‐3M, and C₂ as rapid evaluation for poultry quality testing using SPME‐GC‐MS.     

“From the margins to the center”: Moving towards a resilience-based model of supervision for queer people of color supervisors.

Informed by the authors’ experiences as queer people of color, this article proposes a model of supervision that encourages queer people of color supervisors to draw upon their own histories of oppression and resilience in providing culturally competent and affirmative supervision to trainees. The Queer People of Color Resilience-Based Model of Supervision references models of supervision that typically focus on supervisee development to explore ways in which supervisor development may also benefit the supervision process. This model integrates the multicultural supervision domains (Ancis & Ladany, 2001) with queer models of supervision (Halpert, Reinhardt, & Toohey, 2007) in order to address how racism and heterosexism both may influence the supervision process. The authors share critical incidents from their own development as supervisors, a case study, and specific suggestions for supervision to bring attention to the unique concerns of queer people of color who provide supervision. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Plant Essential Oils as Active Antimicrobial Agents

Essential oils derived from plants have been recognized for decades to exhibit biological activities, including antioxidant, anticancer, and antimicrobial attributes. Antimicrobial activities of these natural plant materials have been intensively explored in recent years, mainly in response to the overwhelming concern of consumers over the safety of synthetic food additives. Gram-negative organisms are believed to be slightly less sensitive to essential oils than Gram-positive bacteria. Generally, a higher concentration is required to obtain the same efficacy in foods than in synthetic media. The combinations of different types of essential oils or with other food additives have been found to potentially exhibit synergistic if not additive effects. This suggests a cost-efficient and wholesome alternative to both food industry and consumers, at the same time adhering to the hurdle technology in inhibiting proliferation of foodborne pathogens. This review aims to examine the conventional methods commonly used for assessment of antimicrobial activities of essential oils and phytochemicals, the use of these substances as antimicrobials in food products, factors that affect their efficacy, synergism between components or with available food preservatives as well as the challenges and future directions of using essential oils and phytochemicals as natural food preservatives.     

Antioxidant activity of a hydrothermal extract from watermelons

In this study, the antioxidant activity of hydrothermal extracts of different parts of watermelons (flesh, white rind, and green rind) was evaluated. Each part of the watermelons was extracted at temperatures ranging from 100 °C to 300 °C for 10, 30, or 60 min. The highest total phenol content was observed for the green rind extracted at 300 °C for 30 min with 7626.52 μg gallic acid equivalents (GAE)/g, whereas the phenol content of the untreated green rind extract was 715.15 μg GAE/g. The antioxidant activity of the watermelon parts increased with increase in treatment temperature and time. In GC–MS analysis, catechol, 4-methylcatechol, pyrogallol, and 1,2,4-benzenetriol were detected after hydrothermal extraction at 300 °C for 30 min. These results indicate that hydrothermal extraction is an efficient process for increasing the antioxidant activity of watermelon extracts.     

Green tea catechins upregulate superoxide dismutase and catalase in fruit flies

Chinese Longjing green tea is an excellent source of polyphenol antioxidants. HPLC analysis revealed that Longjing green tea catechin extract (GTC) contained 62% epigallocatechin gallate (EGCG), 19% epigallocatechin (EGC), 9% epicatechin gallate (ECG), and 7% epicatechin (EC). Investigating the effect of GTC on the lifespan of Drosophila melanogaster, we observed that a 10 mg GTC/mL diet could prolong its 50% survival time by 36% and mean lifespan by 16%. This was consistent with 17% reduction in total body lipid hydroperoxide (LPO) level in GTC-treated flies compared to the control group. Supplementation of 10 mg GTC/mL diet increased the survival time only in wild type Oregon-R-C (OR) but not in two mutant fly lines, SOD(n108)/TM3 (gene for superoxide dismutase (SOD) was knocked out) and Cat(n1)/TM3 (gene for catalase was knocked out), when the flies were challenged with paraquat or hydrogen peroxide. Accordingly, SOD and catalase activities in OR wild type increased by 40 and 19%, respectively. RT-PCR analysis indicated that the genes for copper-zinc containing SOD (CuZnSOD), manganese containing SOD (MnSOD), and catalase were upregulated. It was concluded that prolonging lifespan by GTC in D. melanogaster was influenced, among others, by upregulation of endogenous antioxidant enzymes.     

Application of Light‐Emitting Diodes in Food Production,Postharvest Preservation,and Microbiological Food Safety

Light‐emitting diodes (LEDs) possess unique properties that are highly suitable for several operations in the food industry. Such properties include low radiant heat emissions; high emissions of monochromatic light; electrical, luminous, and photon efficiency; long life expectancy, flexibility, and mechanical robustness. Therefore, they reduce thermal damage and degradation in crops and foods and are suitable in cold‐storage applications. Control over spectral composition of emitted light results in increased yields and nutritive content of horticultural or agricultural produce. Recently, LEDs have been shown to preserve or enhance the nutritive quality of foods in the postharvest stage, as well as manipulate the ripening of fruits, and reduce fungal infections. LEDs can be used together with photosensitizers or photocatalysts to inactivate pathogenic bacteria in food. UV LEDs, which are rapidly being developed, can also effectively inactivate pathogens and preserve food in postharvest stages. Therefore, LEDs provide a nonthermal means of keeping food safe without using chemical sanitizers or additives, and do not accelerate bacterial resistance. This article provides a review of the technology of LEDs and their role in food production, postharvest preservation, and in microbiological safety. Several challenges and limitations are identified for further investigation, including the difficulty in optimizing LED lighting regimens for plant growth and postharvest storage, as well as the sensory quality and acceptability of foods stored or processed under LED lighting. Nevertheless, LED technology presents a worthy alternative to current norms in lighting for the growth and storage of safe and nutritious food.     

最小二乘法拟合大气激光雷达回波信号估算消光系数边界值

报道了一种使用最小二乘法拟合大气激光雷达回波信号，计算消光系数边界值的算法。对于无云层天气条件，利用最小二乘法对回波信号全程拟合获得大气消光系数边界值，在有云层天气下，先将激光雷达信号在大气中的传输光路分解为云层区和非云层区，忽略回波信号中的云层信息，并假设在非云层区大气近似均匀，利用最小二乘法拟合获得大气消光系数边界值。最后利用消光系数边界值求解激光雷达方程，反演获得大气消光系数，实际计算证明，用此算法可获得与实际更为接近的大气消光系数反演结果。     

Preliminary evaluation of flow-through immunocapture followed by real-time PCR for the detection of Salmonella serovars on tomato surfaces within 8 hours

This study reports a preliminary evaluation of flow-through immunocapture (FTI) followed by real-time PCR (FTI-PCR) for the detection of Salmonella serovars on tomato surfaces within 8 h. The FTI-PCR method was compared with real-time PCR, direct plating of FTI beads on xylose lysine desoxycholate (XLD), and the conventional culture method for Salmonella found in the U.S. Food and Drug Administration's (FDA) Bacteriological Analytical Manual (BAM). Unwaxed green tomatoes were spot inoculated with a five-serovar Salmonella cocktail on smooth surfaces at levels of 10(0) to 10(4) CFU per tomato and washed in lactose broth (LB) using a shake-rub method. The resulting LB rinse was incubated at 37 degrees C for 4 h prior to analysis by FTI-XLD, real-time PCR, or FTI-PCR and for 24 h as the first step in the BAM Salmonella culture method. For FTI-XLD, the observed lowest detection level (LDL) was 4.6 x 10(1) CFU per tomato. There was no significant difference in performance between the FTI-XLD method and the BAM Salmonella culture method (P > 0.05); however, the FTI-XLD method reduced the overall assay time by 48 h. For real-time PCR and FTI-PCR, the observed LDLs were 4.6 x 10(1) and 9.2 x 10(0) CFU per tomato, respectively. The FTI-PCR method was superior to the BAM Salmonella culture method (P < 0.05) for the detection of Salmonella serovars on tomato surfaces and was completed within 8 h.