Highly Efficient and Water‐Insensitive Self‐Healing Elastomer for Wet and Underwater Electronics

Integrating self‐healing capabilities into soft electronic devices increases their durability and long‐term reliability. Although some advances have been made, the use of self‐healing electronics in wet and/or (under)water environments has proven to be quite challenging, and has not yet been fully realized. Herein, a new highly water insensitive self‐healing elastomer with high stretchability and mechanical strength that can reach 1100% and ≈6.5 MPa, respectively, is reported. The elastomer exhibits a high (>80%) self‐healing efficiency (after ≈ 24 h) in high humidity and/or different (under)water conditions without the assistance of an external physical and/or chemical triggers. Soft electronic devices made from this elastomer are shown to be highly robust and able to recover their electrical properties after damages in both ambient and aqueous conditions. Moreover, once operated in extreme wet or underwater conditions (e.g., salty sea water), the self‐healing capability leads to the elimination of significant electrical leakage that would be caused by structural damages. This highly efficient self‐healing elastomer can help extend the use of soft electronics outside of the laboratory and allow a wide variety of wet and submarine applications.     

Measurement and Risk Scales of Crane-Related Safety Factors on Construction Sites

This paper addresses quantitative measurement and risk scales of safety hazards on construction sites due to the work of tower cranes. Hazard measurement and risk scales are essential components of an integrated model aimed at quantitatively determining the safety level of individual construction sites, on a comparative basis. The paper focuses on two factors identified in earlier studies as considerably affecting safety on sites with tower cranes, “overlapping cranes” and “operator proficiency.” These two factors are inherently different from each other in their characteristics and therefore also in the methods used to measure both the factors and the risk resulting from them. A probability-based method was prescribed for the measurement of overlapping cranes, while the analytical hierarchy process method and knowledge elicitation from experts were applied to develop metrics for operator proficiency. In both cases, an intimate understanding of the crane work environment is necessary. The uniform format and specific methodologies presented here can be used in the development of measurement techniques and risk scales for other safety factors concerning crane operation on construction sites.     

Abnormal cervical cytology in the teen-ager: a continuing problem

Abnormal cervical cytology is being discovered in an alarming number of sexually active teen-agers. Over an 18 month period, cytology consistent with mild dysplasia or worse was noted in 188 of 2,655 teen-agers screened. This represents a rate of 70.8 per thousand. Colposcopically directed biopsies in 65 patients revealed 15 cases of severe dysplasia-carcinoma in situ. Cryosurgery was the principle method of treatment and, combined with colposcopy, is a safe and effective means of managing these patients.     

Chiral Synthesis via Organoboranes 23. Enantioselective Ring Opening of meso-Epoxides with B-Halodiisopinocampheylboranes. The First General Synthesis of Optically Active 1,2-Halohydrins

B-Halodiisopinocampheylboranes, Ipc₂BX, where X is Cl, Br, or I, cleave cyclohexene oxide at low temperatures to give the 1,2-halohydrins, in 22, 84, and 91% enantiomeric excess (ee), respectively. 1,2-Epoxycyclohex-4-ene is converted to the bromohydrin and iodohydrin in 84 and 91% ee. cis-2,3-Epoxybutane, cis-3,4-epoxyhexane, and cyclopentene oxide were also studied with all three halides. In general, optical induction increases in the order I > Br > Cl for any given epoxide. Thus cis-2,3-epoxybutane furnishes the corresponding chlorohydrin in 35% ee, the bromohydrin in 69% ee, and the iodohydrin in 78% ee. In certain cases recrystallization provides essentially optically pure material, e.g., (1R, 2R)-2-bromocyclohexanol, (1R, 2R)-2-iodocyclohexanol and (1R, 2R)-2-iodocyclohex-4-en-1-ol. In all cases examined ^dIpc₂BX (derived from (+)-α-pinene) provide (1R, 2R) halohydrins, in which the enantiotopic S C—O bond is cleaved. Ring cleavage occurs in an anti-periplanar manner, consistent with an S_N2 type reaction pathway. Modified B-chloromonoisopinocampheylboranes, IpcBCl(OR), cleave cyclohexene oxide at a slower rate but furnish the chlorohydrin in up to 35% ee (R = Bnz). This study is not only a novel application of chiral haloboranes, but constitutes the first general synthesis of symmetrical optically active 1,2-halohydrins.     

Cluster analysis using multi-algorithm voting in cross-cultural studies

The goal of this study was to overcome three main shortcomings in using a single algorithm to determine a particular clustering of a phenomenon. We addressed this issue by considering cross-cultural research as a case in point and applied Multi-Algorithm Voting (MAV) methodology to cluster analysis. Specifically, this study was designed to provide more systematic supportive decision tools for researchers and managers alike when attempting to cluster analyzing phenomena. To assess the merits of the methodology of MAV for cluster analysis, we analytically examined cross-cultural data from Merritt [Merritt, A. (2000). Culture in the cockpit Do Hofstede’s dimensions replicate? Journal of Cross-Cultural Psychology, 31, 283–301] study as well as data scored and ranked by Hofstede [Hofstede, G. (1980). Culture’s consequences: International differences in work-related values. Beverly Hills, CA: Sage; Hofstede, G. (1982). Values survey module (Tech. Paper). Maastricht, The Netherlands: Institute for Research on Intercultural Cooperation].Our study contributes to the literature in several ways. From a methodological point of view, we show how researchers can avoid arbitrary decisions in determining the number of clusters. We provide the researcher with more compelling and robust methodologies not only for analyzing the results of cluster analysis, but also for more better-grounded decision-making through which theoretical insights and implications can be drawn.     

Activated diffusion in relaxed porous clusters

We study diffusion through disordered porous structures, where the size of the diffusing particle is of the order of the pore diameter, and focus on the effect of particle-wall interactions. Such ‘configurational diffusion’ is important in catalysis, separation, and membrane technology, yet it is still poorly understood. We consider three types of cluster cluster aggregation (CCA) structures using simulations carried out on a cubic lattice. Namely, (1) next-neighbor (classic) CCA, where each site may have up to six nearest neighbors; (2) CCA where each site may have up to 26 nearest neighbor in its first coordination shell; and (3) a relaxed CCA solid formed by a process of energy minimization. We find that at low interaction strengths, diffusivity through the various types of CCA structure of similar porosity is independent of the mode of preparation and can be well predicted. However, at high interaction strengths which inhibit the diffusivity considerably, clusters characterized by lower surface-to-volume ratio display lower diffusivities. We suggest a simple model that accounts for the dependence of the diffusivity on the interaction parameter.     

Occurrence of p-nonylphenol isomers in wild species of Cichorium endivia subsp. divaricatum

p-Nonylphenol isomers and other aromatic compounds were found in roots and stalks of the plant Cichorium endivia subsp. divaricatum These compounds were characterized by high-resolution capillary GC-MS.