ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAn Inexpensive Data Logging SystemD'Arcy H. Lorimer and Alexis T. BellCite this: Ind. Eng. Chem. Fundamen. 1976, 15, 1, 71–74Publication Date (Print):February 1, 1976Publication History Published online1 May 2002Published inissue 1 February 1976https://pubs.acs.org/doi/10.1021/i160057a013https://doi.org/10.1021/i160057a013research-articleACS PublicationsRequest reuse permissionsArticle Views19Altmetric-Citations1LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access options Get e-Alerts
In the interplay between cancer and immune system, tumor cells employ several mechanisms to evade the immune response [1]. One such mechanism is the suppression of MHC class I expression, which strongly reduces the antigenicity of tumor cells, therefore preventing an immune response mediated by cytotoxic T cells. Impaired MHC expression is generally common among tumors and in one systematic study was detected in the majority of breast cancer samples [3]. The immune system has evolved strategies to “sense” the lack of MHC class I expression on transformed cells. Indeed, MHC-deficient tumor cells induce a strong response mediated by Natural Killer (NK) cells, a cytotoxic subtype of innate lymphoid cells that play an important role in immunity against cancer [2]. Many tumors with impaired MHC class I expression are malignant and progress, however, suggesting that they have evaded control by the immune response [3]. In our recent publication in The Journal of Clinical Investigation, we found that NK cells become functionally anergic (i.e. show suppressed functional activity) after prolonged exposure to MHC-deficient tumor cells in vivo. Anergy was characterized by reduced ability to phosphorylate intracellular kinases, such as ERK1/2 or AKT, and to produce effector cytokines or to disgorge killer granules after ex vivo stimulation of the tumor infiltrating NK cells [4]. Therefore our results revealed a new mechanism employed by MHC-deficient tumors to escape from NK cell responses. These findings are in accord with previous studies showing that human NK cells are often dysfunctional in oncological patients [2]. In an effort to revert the functional anergy of NK cells within MHC-deficient tumors, we treated tumor-bearing mice with pro-inflammatory cytokines. Some mice received a combination of recombinant IL-12 and IL-18 whereas another cohort of mice was treated with a mutant form of IL-2 called a “superkine” [5], which binds with high affinity to the IL-2 receptor even when it lacks the receptor α-chain (CD25). Both treatments reverted the functional anergy of tumor infiltrating NK cells and significantly increased the survival of mice bearing MHC class I-deficient tumors [4]. In published studies, pro-inflammatory cytokines provided promising results in pre-clinical models and some partial efficacy in clinical trials of cancer patients, albeit with significant toxicity. In our hands, cytokine treatments were relatively non-toxic and increased the life-span of tumor-bearing animals. However, neither of the two treatments were sufficient to eradicate tumors in all animals once they were established, and, depending on the experiment, between 20 and 80% of the mice succumbed [4]. Recent advances in immuno-oncology have led to the development of drugs that boost T cell responses against tumors, based on the ability of T cells to recognize tumor neo-antigens [6]. However, MHC class I-deficient tumor cells cannot present neo-antigens and are poor targets for cytotoxic T cells, revealing the need for alternative strategies to marshal immune responses leading to tumor elimination. In light of our results, cytokine treatments should be re-explored in terms of efficacy vs toxicity, specifically in patients where the immune response against tumors is characterized by a strong NK cell component, and especially in cases where tumors exhibit MHC-deficiency. Strategies to mobilize an NK cell response against tumors include induction of antibody-dependent cellular cytotoxicity or treatment with antibodies that target inhibitory receptors expressed on the surface of NK cells [7]. In a scenario where NK cell responses to tumor cells can be induced/boosted by such treatments, one potential caveat could be that tumor cells could still be able to induce functional anergy on NK cells, therefore reducing or abolishing the efficacy of the treatment. Cytokine therapy could be therefore combined with these treatments in order to prevent/revert the induction of NK cell anergy, and provide additional therapeutic benefit. The adverse effects caused by cytokine treatment could be circumvented by using engineered version of cytokines with reduced toxicity, such as the aforementioned IL-2 superkine. Furthermore, since cytokines would not be employed as a mono-agent, it is possible that lower, less toxic doses would suffice to prevent NK cell anergy. Preclinical studies and a better understanding of the molecular pathways stimulated by immunotherapy will presumably provide additional support for employing cytokine therapy in combinatorial treatments for amplifying the NK-mediated anti-tumor response.
Abstract Definitions of passivity and losslessness are presented that apply to n ‐port networks which are not necessarily linear, time‐invariant, or lumped; in fact, these definitions apply to any n ‐port that has an abstract dynamical system representation. For lumped, non‐linear n ‐port networks that can be mathematically represented by a finite‐order dynamical system, conditions for passivity and losslessness are formulated in terms of properties of the state equation function, the output function, etc. These conditions can be verified without solving the state equation, and can be viewed as non‐linear generalizations of the well‐known time‐domain and frequency‐domain passivity and losslessness conditions for linear time‐invariant lumped n ‐port networks.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Site-isolated Ta(V) centers were introduced onto the surface of a mesoporous SBA-15 support via the thermolytic molecular precursor method. After thermal treatment under oxygen, the resulting Si-OH and Ta-OH sites of TaSBA15-O(2)were modified with a series of trimethyl group 14 species, Me(3)E-, by treatment with Me(3)E-NMe(2) (E = Si, Ge, Sn) reagents. The resulting surface-modified catalysts (Me(3)E)(cap)TaSBA15 exhibit a significantly increased rate of cyclohexene epoxidation with H(2)O(2) as an oxidant, and provided a decreased amount of allylic oxidation products with respect to the unmodified material, TaSBA15-O(2). The rate of nonproductive H(2)O(2) decomposition, as monitored via (1)H NMR spectroscopy, significantly decreased after the surface modification. The structure of the TaSBA15 catalysts and potential Ta(V) epoxidation intermediates (formed upon treatment of Ta(V) materials with H(2)O(2)) were probed using UV-visible absorbance and diffuse-reflectance UV-visible spectroscopy. A Ta(V)(η(2)-O(2)) intermediate species is proposed for the TaSBA15-O(2), (Me(3)Si)(cap)TaSBA15, and (Me(3)Ge)(cap)TaSBA15 catalysts, while intermediate species for the (Me(3)Sn)(cap)TaSBA15 catalysts could not be characterized.
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Este artículo es dedicado a la memoria de Aaron, jovencito español y amigo del gimnasio, a quien el ring no lo salvó de los peligros de la calle. Este trabajo se benefició de las respuestas, los comentarios críticos y el aliento de una serie de colegas, entre los cuales se encuentran Pierre Bourdieu, Rogers Brubaker, Dan Chambliss, S. Lynn Chancer, Rick Fantasia, Harvey Molotch, Bill Wilson, y los miembros del Centro de Sociología Europea en París. También agradezco a mis colegas de la "la dulce ciencia", que me enseñaron mucho más que a lanzar gancho de izquierda, y a mi familia y amigos que me apoyaron moralmente durante este extenuante proyecto (con mención especial para Elizabeth Bonamour du Tartre, una importante asistente en el lugar). Esta investigación fue posible en parte por el apoyo financiero de la Maison des sciences de l homme, un Lavoisier Fellowship del Gobierno Francés y la Fundación Milton de la Universidad de Harvard.
Reactions of 1 and 2 equiv of HOSi(OtBu)3 with Cr(OtBu)4 afforded the first Cr(IV) alkoxysiloxy complexes (tBuO)3CrOSi(OtBu)3 (1) and (tBuO)2Cr[OSi(OtBu)3]2 (2), respectively. Both 1 and 2 contain pseudotetrahedral d2 chromium centers and crystallize in the monoclinic space group P21/n with four molecules in the unit cell. The high-yielding, convenient synthesis of 1 makes this complex a useful single-source molecular precursor, via the thermolytic molecular precursor method, to Cr/Si/O materials. The thermal transformations of 1 and 2 to chromia−silica materials occurred at low temperatures (≤180 °C), to give isobutene as the major carbon-containing product. The material generated from the solid-state conversion of 1 (CrOSiss) contained both micro- and mesoporosity with an unexpectedly high surface area of 315 m2/g that was slightly reduced to 275 m2/g after calcination at 500 °C in O2. The xerogel obtained by the thermolysis of an n-octane solution of 1 (CrOSixg) had a surface area of 315 m2/g that was reduced to 205 m2/g upon calcination at 500 °C. The nitrogen adsorption−desorption isotherm for the xerogel had characteristics indicating both microporosity and textural mesoporosity. Powder X-ray diffraction (PXRD) analysis was used to demonstrate that Cr2O3 was the only species that crystallized in CrOSiss and CrOSixg after calcination at temperatures up to 1200 °C in O2. Elemental analyses of these materials revealed that the Cr:Si ratio was very close to 1:1, indicating that the original stoichiometry of the precursor is retained upon thermal conversion to Cr/Si/O materials. Both materials contained very low amounts of carbon after calcination in O2 at 500 °C. In the oxidative dehydrogenation of propane, CrOSixg (calcined at 500 °C) displayed intrinsic activities for propene formation that were up to 3 times higher than those for CrOSiss (calcined at 500 °C). In addition, the selectivity for propene formation was higher for the more active CrOSixg catalyst.
We present Resilient Distributed Datasets (RDDs), a distributed memory abstraction that allows programmers to perform in-memory computations on large clusters while retaining the fault tolerance of data flow models like MapReduce. RDDs are motivated by two types of applications that current data flow systems handle inefficiently: iterative algorithms, which are common in graph applications and machine learning, and interactive data mining tools. In both cases, keeping data in memory can improve performance by an order of magnitude. To achieve fault tolerance efficiently, RDDs provide a highly restricted form of shared memory: they are read-only datasets that can only be constructed through bulk operations on other RDDs. However, we show that RDDs are expressive enough to capture a wide class of computations, including MapReduce and specialized programming models for iterative jobs such as Pregel. Our implementation of RDDs can outperform Hadoop by 20x for iterative jobs and can be used interactively to search a 1 TB dataset with latencies of 5-7 seconds
Staged-O2 introduction and the effects of O2 concentration on primary and secondary reactions were examined during oxidative dehydrogenation on V2O5/γ-Al2O3 containing predominately isolated monovanadates. Cofeed and staged-O2 introduction modes led to similar ethane dehydrogenation and combustion rates, despite significant differences in the average O2 concentrations, as expected from their zero-order O2 dependences. The rate of ethene conversion to COx, however, was lower when O2 coreactants were introduced gradually as ethane conversion increased. These effects reflect inhibition of homogeneous ethene combustion pathways, which in contrast with their heterogeneous counterparts show a positive dependence in O2. Axial O2 distribution using multiple injectors or membranes will therefore influence alkene yields only by decreasing homogeneous alkene oxidation rates. Homogeneous contributions are much smaller in large reactors, because catalyst-to-volume ratios are greater than those in laboratory reactors. Other oxidation reactions occurring via redox cycles with lattice oxygens as the most abundant intermediates are expected to exhibit a response similar to that of O2 staging.
