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.     

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.     

河道治理工程水土保持设计

河道治理工程的实施会对工程区域内的自然生态环境和水土保持带来负面影响。以独流减河左堤治理工程为例 ,分析工程建设中可能造成的水土流失影响 ,从工程和生物两方面提出水土保持的防治措施 ,并对其投资进行了初步估算。     

Suggestions for the quantitative X-ray microanalysis of thin sections of frozen-dried and embedded biological tissues

When a microregion in a thin section of frozen-dried and embedded tissue is analysed by the conventional electron-probe X-ray continuum-normalization method, the measured quantity is in mmol of element per kg of embedded specimen. As each microregion contains an unknown amount of embedding medium, this quantity generally lies indeterminately somewhere within the wide range between mmol of element per kg of hydrated tissue and mmol of element per kg of dehydrated tissue. However, if a ‘tag’ element is incorporated in the embedding medium, the contribution of the medium to the local continuum count in each probed field should be measurable, and the X-ray data may then unambiguously yield mmol of element per kg of dehydrated tissue. This result should not be affected by shrinkage on freeze-drying or by incomplete replacement of water by embedding medium. The same X-ray data can additionally provide estimates of mmol of element per unit volume, mmol of element per kg of hydrated tissue and local dry-mass fraction. However, these estimates are subject to errors due to tissue shrinkage, incomplete replacement of water and beam damage.     

沙漠生物结皮土壤发育特征的研究

通过对沙漠生物结皮层相关的土壤特性研究表明,结皮层不仅具有明显的养分富集和细粒物质的聚集作用,而且结皮层腐殖质成份的含量以及其分子结构和复杂程度也在增加。腐殖质光学特性的变化趋势明显反映了不同地区结皮层土壤发育的地带性特征。结皮层持水量明显高于沙层,并对降水再分配有一定影响。