Core Softening in Cavernously Weathered Tonalite

Tonalite exhibiting cavernous weathering at Catavina, Baja California, was investigated to determine the factors which contribute to differential hardness within the rock. Soft cores have a high degree of chemical weathering as indicated by kaolinite content. Hematite formed from the leaching of biotite occurs in coatings on rock surfaces, but the hardening effect of the coating is insignificant compared to the core-softening of the interior. The hardness, measured by an abrasion resistance hardness tester, is inversely correlated with kaolinite content in the tonalite. A one-dimensional water flow model was developed for core-softened. cavernously weathered boulders. It indicates that during infiltration and dessication the moisture flux is greatest through the cavern interior wall because of changes in the hydraulic conductivities induced by core softening. Therefore, the cavern interior wall should have the greatest weathering rate in the boulder

Asymptotics for models of non-stationary diffusion in domains with a surface distribution of obstacles

We consider a time-dependent model for the diffusion of a substance through an incompressible fluid in a perforated domain ??, urn:x-wiley:mma:media:mma5323:mma5323-math-0001 with n?=?3,4. The fluid flows in a domain containing a periodical set of ?obstacles? (?\??) placed along an inner (n???1)?dimensional manifold urn:x-wiley:mma:media:mma5323:mma5323-math-0002. The size of the obstacles is much smaller than the size of the characteristic period ?. An advection term appears in the partial differential equation linking the fluid velocity with the concentration, while we assume a nonlinear adsorption law on the boundary of the obstacles. This law involves a monotone nonlinear function ? of the concentration and a large adsorption parameter. The ?critical adsorption parameter? depends on the size of the obstacles , and, for different sizes, we derive the time?dependent homogenized models. These models contain a ?strange term? in the transmission conditions on ?, which is a nonlinear function and inherits the properties of ?. The case in which the fluid velocity and the concentration do not interact is also considered for n???3.The authors would like to thank the anonymous referees for their careful reading of the manupscript and useful comments. The work has been partially supported by MINECO, MTM2013-44883-P

Determination of the calcium channel distribution in the olfactory system

In this paper we study a linear inverse problem with a biological interpretation, which is modeled by a Fredholm integral equation of the first kind. When the kernel in the Fredholm equation is represented by step func- tions, we obtain identifiability, stability and reconstruction results. Further- more, we provide a numerical reconstruction algorithm for the kernel, whose main feature is that a non-regular mesh has to be used to ensure the invert- ibility of the matrix representing the numerical discretization of the system. Finally, a second identifiability result for a polynomial approximation of degree less than nine of the kernel is also established

Sustainable Triazine-Based Dehydro-Condensation Agents for Amide Synthesis

Conventional methods employed today for the synthesis of amides often lack of economic and environmental sustainability. Triazine-derived quaternary ammonium salts, e.g., 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM(Cl)), emerged as promising dehydro-condensation agents for amide synthesis, although suffering of limited stability and high costs. In the present work, a simple protocol for the synthesis of amides mediated by 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) and a tert-amine has been described and data are compared to DMTMM(Cl) and other CDMT-derived quaternary ammonium salts (DMT-Ams(X), X: Cl- or ClO4-). Different tert-amines (Ams) were tested for the synthesis of various DMT-Ams(Cl), but only DMTMM(Cl) could be isolated and employed for dehydro-condensation reactions, while all CDMT/tert-amine systems tested were efficient as dehydro-condensation agents. Interestingly, in best reaction conditions, CDMT and 1,4-dimethylpiperazine gave N-phenethyl benzamide in 93% yield in 15 min, with up to half the amount of tert-amine consumption. The efficiency of CDMT/tert-amine was further compared to more stable triazine quaternary ammonium salts having a perchlorate counter anion (DMT-Ams(ClO4)). Overall CDMT/tert-amine systems appear to be a viable and more economical alternative to most dehydro-condensation agents employed today

May 1,3,5-Triazine derivatives be the future of leather tanning? A critical review

Leather is produced by a multi-step process among which the tanning phase is the most relevant, transforming animal skin collagen into a stable, non-putrescible material used to produce a variety of different goods, for the footwear, automotive, garments, and sports industry. Most of the leather produced today is tanned with chromium (III) salts or alternatively with aldehydes or synthetic tannins, generating high environmental concern. Over the years, high exhaustion tanning systems have been developed to reduce the environmental impact of chromium salts, which nevertheless do not avoid the use of metals. Chrome-free alternatives such as aldehydes and phenol based synthetic tannins, are suffering from Reach restrictions due to their toxicity. Thus, the need for environmentally benign and economically sustainable tanning agents is increasingly urgent. In this review, the synthesis, use and tanning mechanism of a new class of tanning agents, 1,3,5-triazines derivatives, have been reported together with organoleptic, physical mechanical characteristics of tanned leather produced. Additionally environmental performance and economic data available for 1,3,5-triazines have been compared with those of a standard basic chromium sulphate tanning process, evidencing the high potentiality for sustainable, metal, aldehyde, and phenol free leather manufacturing

Agri-business and nobility in Northern Italy : land, investments and markets (1815-1861)

Traditionally, the contribution of nobility to the enhancement of northern Italy\u2019s land and agro food production during the 19th century has been undervalued. The paper aims to address the question of whether the nobility considered land mainly as a means to collect rents with the least effort, maintaining their social status, or rather \u2013 as we affirm \u2013 they also developed entrepreneurial behaviour founded on a sort of class-expertise. Indeed, in a considerable number of cases, they owned and invested capital in large estates with a well-structured administration which they inherited from the past and improved upon; they organised complex production systems, introducing technical innovation; they were directly interested in market trends; they could take advantage of their local and international social networks. Finally, they acted as models for many of the bourgeoisie who became richer and became landowners themselves. Through ongoing extensive research using primary sources (fiscal sources, notarial deeds and family archives), the essay will first focus on the general features of the noblemen\u2019s involvement in the management and improvement of lands, through agrarian innovation and experimentation (e.g. in silk or wine production), according to the circumstances of the markets. The second part will illustrate the case of the Lombardy noble family Lucini Passalacqua, who seems to exemplify the tendency towards innovation which was widespread among the region\u2019s noble landowners. The third part of the paper will shed light upon the business strategies of Genoese noblemen, traditionally tied to financial businesses, and who, during the 19th century, largely invested in land development, also acquiring vast estates in Piedmont and Lombardy