Microbial susceptibility of various polymers and evaluation of thermoplastic elastomers with antimicrobial additives

The incursion of microbial growth on polymeric products can deteriorate their performance and lead to the development of undesirable staining and odors. A growing trend in the industry has aimed to reduce microbial populations on high-touch surfaces via the use of antimicrobials to protect material aesthetics and durability or to prevent the spread of pathogenic microorganisms. In this study, a variety of plastic substrates (30 unique polymer compounds), including poly(acrylonitrile-co-butadiene-co-styrene), poly(butylene terephthalate), poly(etherimide), various thermoplastic elastomers (TPEs), poly(carbonates), and poly(amides), were screened for susceptibility to microbial attack using American Society for Testing and Materials (ASTM) G21 (fungi susceptibility), Japanese Industrial Standard (JIS) Z2801, and modified ASTM E1428-15a (bacterial susceptibility) test standards. TPEs were determined to be most susceptible to microbial attack under the appropriate environmental conditions. Subsequent studies assessed the use of an antimicrobial additive, zinc pyrithione (ZPT), for potential efficacy in a variety of TPE blends for diverse target market applications. ZPT proved to be very effective in protecting TPEs, reducing Staphylococcus aureus and Escherichia coli populations by 99.9% or more in JIS Z2801 testing and inhibiting fungal growth (rating = 0) according to the ASTM G21 standard.     

Sparse non-convex Lp regularization for cone-beam X-ray luminescence computed tomography

Cone-beam X-ray luminescence computed tomography (CB-XLCT) is an attractive hybrid imaging modality, and it has the potential of monitoring the metabolic processes of nanophosphors-based drugs in vivo. However, the XLCT imaging suffers from a severe ill-posed problem. In this work, a sparse nonconvex L_p (0?p?L₁ regularization. Further, an iteratively reweighted split augmented lagrangian shrinkage algorithm (IRW_SALSA-L_p) was proposed to efficiently solve the non-convex L_p (0?p?p-values (1/16, 1/8, 1/4, 3/8, 1/2, 5/8, 3/4, 7/8) in both 3D digital mouse experiments and in vivo experiments. The results demonstrate that the proposed non-convex methods outperform L₂ and L₁ regularization in accurately recovering sparse targets in CB-XLCT. And among all the non-convex p-values, our L_p(1/4?p?相似文献   

面向二十一世纪的生物农药

简述了农药的发展经历，介绍了国内外生物农药的研究、发展和应用的现状及发展趋势。     

Failure analysis of a broken tooth

Several days after heart surgery, a patient discovered his upper right canine tooth had broken at the root. Such tooth damage, recognized post-operatively, is usually assumed to be caused by blunt mechanical force from an instrument used by the anesthesiologist during placement of a breathing tube at the start of surgery. In this case, the patient had saved the crown portion of the broken tooth, and it was possible to examine the root fracture characteristics. The curvature and direction of the crack path and natural tooth situation suggested that failure could be described through a cantilever beam model. This was confirmed when a whole extracted sample tooth was embedded and broken by a measured force in a manner consistent with the model. The resulting fracture surface matched that of the patient’s broken canine tooth. However, the high load and force direction necessary to fracture the root was inconsistent with forces applied during the anesthesia procedure. The failure analysis and further investigation indicated tooth clenching on the breathing tube during recovery was the likely cause of fracture. This paper presents an alternate explanation for intubation-related dental injury, demonstrates the practicality of fractographic analysis of biological materials, and introduces a methodology for simulating in vitro tooth settings for mechanical testing.     

中低品位硅钙质胶磷矿富集技术探讨

过去的正反浮选工艺具有产生的磷精矿中MgO含量低，产品脱水性能好的优点，但选矿成本较高，直接经济效益不显著，为此对“矿浆无需加温”、正浮选作业“无碱”、“无碳酸盐抑制剂”、反浮选“无需添加磷酸”的“四无”正反浮选新工艺进行了研究，结果表明：该新工艺具有技术指标先进，选矿成本低的优点。     

浓香型瓶装酒库存过程中理化指标的变化

经过对1996年及1999年灌装的种子牌系列浓香型白酒的理化指标检测，发现在贮存过程中理化指标变化很大，总酸，固形物呈上升趋势，总酯，己酸乙酯呈下降趋势,其升降幅度与贮存时间相关，时间越长变化越大，贮存3年的高低度5个样平均总酸上升18．2％，28度样总酸上升28．3％，50度样总酸仅上升11％，固形物平均上升39．2％，28度样上升43％，50度样上升18％，总酯平均下降24％，28度样下降34％，50度样下降31％，己酸己酯平均下降32．4％，28度样下降59％，50度样下降32％，贮存6年的5个样总酸平均上升39．8％，28度样上升52％，50度样上升41％，固形物平均上升71．8％，28度样上升635＜50度样上升77％，总酯平均下降42．4％，28度样下降54％，50度样下降31％，己酸乙酯平均下降51．8％，28度样下降69％，50度样下32%.     

石油测井仪器可靠性指标探讨

在分析常用可靠性指标及其应用现状的基础上，根据可靠性理论及石油测井仪器的特点。提出了石油测井仪器的可靠性模型。在探讨常用可靠性指标对石油测井仪器适用性的同时，提出将平衡稳定工作时间NWTURE和免维修测井井次NOLWNM作为石油测井仪器可靠性指标的思想；探讨了获取可靠性指标的途径。给出了推荐使用的石油测井仪器可靠性指标。     

回转升降生物接触工艺的实验研究

提出了一种具有特殊运转方式的新型RBC系统－－回转升降生物接触工艺，对回转升降生物接触工艺的工作原理和工艺特征进行了论述。并通过动态实验，对回转升降生物接触工艺小型实验装置的性能和效果进行了初步考察。     

Occupational airway diseases in the metalworking industry Part 1: Respiratory infections, pneumonia, chronic bronchitis and emphysema

Occupational airway diseases are now receiving attention in industry, although study is hampered by a lack of readily-available data. The interpretation of the data that is available, and also of the root problems themselves, is itself a difficult problem. This paper has been written as a literature review which it is hoped that other researchers can take either as a starting point or as a refresher.