Letter from John DeLaittre to John Muir, 1910 Jan 10.

THE FARMERS AND MECHANICS SAVINGS BANK OF MINNEAPOLIS115 FOURTH STREET SOUTHJOHN DELAITTRE, PresidentO.C. WYMAN .Vice Pres &Asst. Treas.T.B.JANNEY, 2nd Vice PresN.F.HAWLEY Secy &Treasurer\u3c\u3ebrF.P.GARCKEN, Asst Secy.G.H.RICHARDS, 2nd Asst .Treas.F.P.LEONARD. 3rd Asst. Treas.CLAUDE B.LEONARD, CounselTRUSTEES:H.C.AKELEY JOHN CROSBY JOHN DELAITTRE N.F.HAWLEY T.B.JANNEYC S.LANGDON E.H.MOULTON WM.G.NORTHUP ALFRED F.PILLSBURY JOHN WASHBURNO.C WYMANMINNEAPOLIS, MINN.Jan.10,1910.Mr. John Muir,Martinez, Cal.My dear Mr. Muir:-Pardon me for addressing you. I have read and am now re-reading your book, National Reserves . I cannot express to you the delight I take in reading it and indeed I wish I. knew as much as you do. Where did you learn all of the names of the California flowers? May your tribe increase ; but I am sure there will never be another John Muir like you . You have no conception of the delight I have taken in your book. When you have read a little further you will know the reason why. At the age of twenty or thereabouts I landed in San Francisco Nov. 1852 and went immediately to Murphy\u27s Camp in Calaveras County, You know every inch of the ground there well. I lived there thirteen and one-half years. Knew well for many years Dow, the hunter and first discoverer of the big trees, and two weeks after his discovery, together with him, made one of a party of eight who, after hunting two days, found them and slept one night beneath the Father of the Forest\u27.\u27 I knew well Capt. Hanford, who, with some friends who furnished capital, cut down the big tree, shipped 60 feet of the bark and exhibited it on Broadway, N Y. James L. Sperry, proprietor of the Sperry Hotel, both at Murphy\u27s and at Big Tree Grove, was my imtimate friend and doubtless you knew him well, I am not sure but I have an indistinct recollection that John Muir visited the Grove while I was in Murphy\u27s; but be all this as it may, you can readily see how I am charmed with your book.04579 Mr. John Muir. 2.At the close of the Civil war I left Murphy\u27s and have since lived in this city. This spring if it is possible, I am bound to go into the Yosemite Valley and also revisit my old home in Murphy\u27s. Should I pass through Martinez, I have an idea I would like to stop off for an hour and exchange greetings with you.Indeed you are doing in your books a wonderful work. Your descriptions of Mt. Shasta, Yellow Stone Park and many places in the State of Washington which I have visited are simply grand.Considering that I am a stranger to you, I will make this communication brief.Wishing you a happy new year, long life and many more trips with Brownie through the Grand Sierras and with sincere regards, I am,Yours sincerely,[Illegible]0467

Covalent Adaptable Networks Based on Dynamic Alkoxyamine Bonds

Covalent adaptable networks (CANs) introduce a new paradigm to polymer science, by making static network polymers dynamic and thereby recyclable, reprocessable, and self-healing. The critical feature in CANs is the presence of dynamic covalent linkages within the network structure. A variety of such linkages are introduced into CANs, making the respective networks responsive to various stimuli, such as light, temperature, or pH. Here, CANs based on alkoxyamines as dynamic covalent bonds are reviewed. Alkoxyamines uniquely combine the ability to dynamically form, break, and reform covalent bonds with the possibility to initiate reversible-deactivation radical polymerization. Polymer networks based on alkoxyamines are therefore both adaptive and quasi-living, able to remodel the network structure by nitroxide-exchange reactions (NER) and extend the network structure by nitroxide-mediated polymerization (NMP). In this review, the concepts behind CANs are first introduced and the properties of nitroxides and derived alkoxyamines are discussed. A special focus is set on the ability to tune the response of alkoxyamines to different stimuli, through alteration of their structure. In addition, possible side reactions during dynamic bond exchange and limitations for polymerization are critically reviewed. Subsequently, examples of alkoxyamine-based CANs responsive to different stimuli, such as temperature, light, or chemical triggers, are discussed. Properties and applications of CANs based on alkoxyamines are then discussed. Finally, an outlook is provided on challenges that need to be addressed as well as opportunities that lie within these “living” CANs

Maleimide end-functionalized poly(2-oxazoline)s by the functional initiator route : synthesis and (bio) conjugation

The synthesis of poly(2-ethyl-2-oxazoline)s with a maleimide group at the a chain end was carried out from new sultanate ester initiators bearing a furan-protected maleimide group. The conditions of the polymerization were optimized for 50 degrees C using conventional heating (in contrast to microwave irradiation) to counteract the thermal lability of the cycloadduct introduced to protect the maleimide double bond. At this temperature, a tosylate variant was found to be unable to initiate the polymerization after several days. The controlled polymerization of 2-ethyl-2-oxazoline with a nosylate derivative was, however, successful as shown by kinetic experiments monitored by gas chromatography (GC) and size-exclusion chromatography (SEC). Poly(2-ethyl-oxazoline)s of various molar masses (4500 < M-n < 12 000 g mol(-1)) with narrow dispersity (D < 1.2) were obtained. The stability of the protected maleimide functionality during the polymerization, its deprotection, and the reactivity of the deprotected end group by coupling with a model thiol molecule were proven by H-1 NMR spectroscopy and electrospray ionization mass spectrometry (ESI-MS). Finally, the conjugation of maleimide-functionalized poly(2-oxazoline) to a model protein (bovine serum albumin) was demonstrated by gel electrophoresis and MALDI-ToF mass spectrometry

Reactive block copolymers for patterned surface immobilization with sub-30 nm spacing

Phase-segregating block copolymers are powerful platforms for nanofabrication, particularly when employed as lithographic mask precursors. Surface-reactive polymeric films with distinct sub-30 nm domains are also proposed as covalent docking platforms for scalable, high-resolution molecular patterned immobilization. Here, the well-known self-assembling polystyrene-block-polyisoprene system is the starting point to produce a small library of derivatives with distinct reactive pendant groups (halide, azide, pentafluorophenylalkyl) by nitroxide-mediated radical polymerization. We find that controlling film thickness is crucial to obtain a perpendicular lamellar morphology and that the presence of the functional groups has a limited impact on self-assembly, yet may influence characteristic domain dimensions. Differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS), and atomic force microscopy (AFM) are utilized in concert to assess the phase behavior of the polymers and the surface features of the nanostructures. As a proof-of-concept for the surface reactivity, click chemistry-driven immobilization of a model water-soluble polymer is evidenced by X-ray photoelectron spectroscopy (XPS) and preservation of the underlying morphology is investigated by AFM

Hetero-Diels–Alder Cycloaddition with RAFT Polymers as Bioconjugation Platform

We introduce the bioconjugation of polymers synthesized by RAFT polymerization, bearing no specific functional end group, by means of hetero‐Diels–Alder cycloaddition through their inherent terminal thiocarbonylthio moiety with a diene‐modified model protein. Quantitative conjugation occurs over the course of a few hours, at ambient temperature and neutral pH, and in the absence of any catalyst. Our technology platform affords thermoresponsive bioconjugates, whose aggregation is solely controlled by the polymer chains

Controlled manipulation of enzyme specificity through immobilization-induced flexibility constraints

It is thought that during immobilization enzymes, as dynamic biomolecules, may become distorted and this may alter their catalytic properties. However, the effects of different immobilization strategies on enzyme rigidity or flexibility and their consequences in specificity and stereochemistry at large scale has not been yet clearly evaluated and understood. This was here investigated by using as model an ester hydrolase, isolated from a bacterium inhabiting a karstic lake, with broad substrate spectrum (72 esters being converted; 61.5 U mg$^{-1}$ for glyceryl tripropionate) but initially non-enantiospecific. We found that the enzyme (7 nm × 4.4 nm × 4.2 nm) could be efficiently ionic exchanged inside the pores (9.3 nm under dry conditions) of amino-functionalized ordered mesoporous material (NH$_{2}$-SBA-15), achieving a protein load of 48 mg g−1, and a specific activity of 4.5 ± 0.1 U mg$^{-1}$. When the enzyme was site-directed immobilized through His interaction with an immobilized cationon the surface of two types of magnetic micro-particles through hexahistidine-tags, protein loads up to 10.2 μg g$^{-1}$ and specific activities of up to 29.9 ± 0.3 U mg$^{-1}$, were obtained. We found that ionically exchanged enzyme inside pores of NH2-SBA-15 drastically narrowed the substrate range (17 esters), to an extent much higher than ionically exchanged enzyme on the surface of magnetic micro-particles (up to 61 esters). This is attributed to differences in surface chemistry, particle size, and substrate accessibility to the active site tunnel. Our results also suggested, for the first time, that immobilization of enzymes in pores of similar size may alter the enzyme structures and produce enzyme active centers with different configuration which promote stereochemical conversions in a manner different to those arising from surface immobilization, where the strength of the ionic exchange also has an influence. This was shown by demonstrating that when the enzyme was introduced inside pores with a diameter (under dry conditions) slightly higher than that of the enzyme crystal structure a biocatalyst enantiospecific for ethyl (R)-4-chloro-3-hydroxybutyrate was produced, a feature not found when using wider pores. By contrast, immobilization on the surface of ferromagnetic microparticles produced selective biocatalysts for methyl (S)-(+)-mandelate or methyl (S)-lactate depending on the functionalization. This study illustrates the benefits of extensive analysis of the substrate spectra to better understand the effects of different immobilization strategies on enzyme flexibility/rigidity, as well as substrate specificity and stereochemistry. Our results will help to design tunable materials and interfaces for a controlled manipulation of specificity and to transform non-enantiospecific enzymes into stereo-chemically substrate promiscuous biocatalysts capable of converting multiple chiral molecules

Hetero-Diels-Alder-Cycloaddition mit RAFT-Polymeren als Biokonjugationsplattform

Wir stellen die Biokonjugation von Polymeren vor, die durch RAFT‐Polymerisation mittels Hetero‐Diels‐Alder‐Cycloaddition durch ihren inhärenten terminalen Thiocarbonylthiorest mit einem dienmodifizierten Modellprotein synthetisiert wurden und keine spezifische funktionelle Endgruppe tragen. Die quantitative Konjugation erfolgt im Verlauf einiger Stunden bei Raumtemperatur und nahezu neutralem pH‐Wert und in Abwesenheit jeglichen Katalysators. Unsere Technologieplattform liefert thermoresponsive Biokonjugate, deren Aggregation allein durch die Polymerketten gesteuert wird

Maleimide end-functionalized poly(2-oxazoline)s by the functional initiator route: synthesis and (bio)conjugation

The synthesis of poly(2-ethyl-2-oxazoline)s with a maleimide group at the α chain end was carried out from new sulfonate ester initiators bearing a furan-protected maleimide group. The conditions of the polymerization were optimized for 50 °C using conventional heating (in contrast to microwave irradiation) to counteract the thermal lability of the cycloadduct introduced to protect the maleimide double bond. At this temperature, a tosylate variant was found to be unable to initiate the polymerization after several days. The controlled polymerization of 2-ethyl-2-oxazoline with a nosylate derivative was, however, successful as shown by kinetic experiments monitored by gas chromatography (GC) and size-exclusion chromatography (SEC). Poly(2-ethyl-oxazoline)s of various molar masses (4500 < Mn < 12 000 g mol−1) with narrow dispersity (Đ < 1.2) were obtained. The stability of the protected maleimide functionality during the polymerization, its deprotection, and the reactivity of the deprotected end group by coupling with a model thiol molecule were proven by 1H NMR spectroscopy and electrospray ionization mass spectrometry (ESI-MS). Finally, the conjugation of maleimide-functionalized poly(2-oxazoline) to a model protein (bovine serum albumin) was demonstrated by gel electrophoresis and MALDI-ToF mass spectrometry

A simple route to highly active single-enzyme nanogels

Just add sugar: the synthesis of single-enzyme nanogels, a class of highly robust nanobiocatalysts, is boosted by the addition of carbohydrates. Our methodology is demonstrated with a dozen commercial proteins, spanning a large size interval and a broad domain of applications. In addition, new in-depth structural characterizations are provided.</p