Robert Mayer | Iowa State University (original) (raw)

Papers by Robert Mayer

Advanced Materials, 2012

This paper demonstrates extremely efficient (η(P,max) = 118 lm W(-1) ) ITO-free green phosphoresc... more This paper demonstrates extremely efficient (η(P,max) = 118 lm W(-1) ) ITO-free green phosphorescent OLEDs (PHOLEDs) with multilayered, highly conductive poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) films as the anode. The efficiency is obtained without any outcoupling-enhancing structures and is 44% higher than the 82 lm W(-1) of similar optimized ITO-anode PHOLEDs. Detailed simulations show that this improvement is due largely to the intrinsically enhanced outcoupling that results from a weak microcavity effect.

Journal of Clinical Oncology, Nov 1, 2001

Thesis the University of Texas at Austin 1994 Source Dissertation Abstracts International Volume 55 10 Section B Page 4527, 1994

The primary objective of this work was to demonstrate the viability of silicon-based integrated o... more The primary objective of this work was to demonstrate the viability of silicon-based integrated optoelectronics. Since the commercial foundation of integrated circuit manufacturing is silicon-based, it is an exciting prospect to develop optoelectronics in a material system that is compatible with silicon. However, the indirect band structure and large bandgap of Si makes this material unattractive for development of optoelectronics, as efficient light emission has not been realized. Also, photodetectors in Si material cannot detect optical signals at wavelengths advantageous for fiber-optic communications. Some of these shortcomings can be overcome by introducing a smaller bandgap material such as Ge in Si. The addition of Ge to Si extends the sensitivity range for photodetectors up to lambda = 1.6 mum. Based on this premise, a myriad of passive and active optoelectronic devices can be developed in this material. During the course of this research, low-loss passive waveguides, grating-couplers, directional-couplers and electro-optic Mach-Zehnder modulators, operating at wavelengths important for fiber optic communications were demonstrated in epitaxial Ge_{rm x}Si _{rm 1-x} layers grown by rapid thermal processing chemical vapor deposition (RTPCVD). The modal characteristics of straight waveguides and the coupling characteristics of directional couplers were computer-modeled and the simulation results are presented herein. Enhancement in voltage-bandwidth product has been demonstrated previously for III-V based Multiple Quantum Well (MQW) modulators. This motivated a similar investigation of quantum confinement effects in Ge_{ rm x}Si_{rm 1-x}/Si MQW material. To this end, Ge _{rm x}Si_ {rm 1-x}/Si quantum-well photodetectors were fabricated on material grown by remote plasma chemical vapor deposition, RPCVD, and by molecular beam epitaxy, MBE. The optical and electronic characteristics were analyzed and the results are presented. These devices demonstrated enhanced electroabsorption, and a concomitant red-shift associated with a phonon-assisted Franz-Keldysh Effect. Electrorefraction was calculated in Ge_{rm x} Si_{rm 1-x}/Si MQW material from experimental electroabsorption data using the Kramers-Kronig relationship. The broad scope of optoelectronic devices developed during the course of this research has demonstrated the flexibility of the Ge_{rm x} Si_{rm 1-x} material system for providing optical signal propagation, modulation and detection. This should provide the foundation for future realization of Si-based optoelectronic integrated circuits (OEIC's).

Asco Meeting Abstracts, May 20, 2013

Asco Meeting Abstracts, Jan 20, 2014

Journal of Biological Chemistry, May 25, 1985

The treatment of rats with cis-platinum for 7 days It follows that, in the absence of adenohypoph... more The treatment of rats with cis-platinum for 7 days It follows that, in the absence of adenohypophysis hormones, caused a profound, and seemingly selective, decrease the concentration of cytochrome P-450 in the testis is dimin-(70-80%) in the microsomal cytochrome P-450 levels ished to negligible levels (2,4). in the testis. This decrease was accompanied by The concentration of cytochrome P-450 in the microsomal marked reductions (70-80%) in steroid 17a-hydroxmembranes of rat testis can be modulated by extracellular ylase activity and in Plasma testosterone concentrafactors. Recent studies from this laboratory (3) have shown tion. The treatment of rats with human chorionic gothat anterior pituitary hormones control the concentration of nadotropin Partially restored the cytochrome p-450 cytochrome P-450 in rat testis through factors which neither COncentration and 17a-hydroxy1ase activity and perinvolve the production of the heme prosthetic moiety nor that mitted the plasma testosterone level to approach 'Onof the apoprotein portion of the molecule; rather, the control trol values. The effect of cis-platinum on the testicular appears to involve the effective association of heme molecule cytochrome p-450 appeared to deficiencies with the apocytochrome. On the other hand, the control of in heme metabolic processes, in so far that neither was the activity of b-aminolevulinate synthetase decreased, cytochrome P-450 concentration in rat testis by metal ions nor was that of heme oxygenase increased. These en-appears to involve the regulation of the activities of the zymes are rate-limiting in heme biosynthesis and deg-enzymes of heme metabolic pathway in Leydig cells (4, 5). radation pathways, respectively. ~l~~, the activities of The regulatory effect of metal ions on heme metabolic activ-uroporp~yr~nogen I synthetase, b-aminolevulinate de-ities is predominantly exerted at the levels Of 6-aminolevulihydratase, and ferrochelatase and the concentration of nate synthetase and heme oxygenase, the rate-limiting entotal porphyrins in the testis remained unchanged. The zymes in the Pathways of heme biosynthesis (6) and desasodium dodecyl sulfate-gel electrophoresis of the mi-dation (7, 8), respectively. Among metal ions, platinum is crosomal preparation did not reveal a diminished level known for its remarkable activity to alter heme metabolism of apocytochrome; however, in this preparation, heme by inhibiting the activity of 6-aminolevulinate synthetase and could not be detected in molecular weight regions corenhancing that of heme oxygenase (9). Recently, a platinumresponding to cytochome €'-450. The microsomal CY-coordinated complex, cis-dichlorodiammineplatinum (cistochrome ba and the mitochondrial heme concentraplatinum), has been identified as a single most effective tions were not decreased in cis-platinum-treated rats. chemotherapeutic agent against a broad spectrum of human It is suggested that the mechanism of depletive action malignancies (lo), including the steroid-dependent prostatic Of cis-platinum On cytochrome p-450 inand testicular cancers (11, 12). A consequence of treatment valves an impairment of the effective assembly of heme of testicular cancer with regimens including &-platinum is and apoprotein nxh&% It is further suggested that sterility, the molecular basis of which remains undefined. the anterior pituitary hormones the factor(s) The present study was undertaken to explore the molecular involved in this assembly, a process which is interrupted by &-platinum. basis for the activity of cis-platinum as it pertains to testicular heme and hemoprotein metabolism and cytochrome P-450dependent steroidogenesis.

Asco Meeting Abstracts, Jul 15, 2004

Background: In the treatment of advanced pancreatic cancer, chemotherapy regimens utilizing prolo... more Background: In the treatment of advanced pancreatic cancer, chemotherapy regimens utilizing prolonged infusions of gemcitabine or combinations of gemcitabine and other agents have been associated with higher objective tumor response rates and, in some ...

Cancer Research, Oct 1, 1980

Chemotherapeutic agents may damage gastrointestinal epi thelium and thereby impair the mucosal ba... more Chemotherapeutic agents may damage gastrointestinal epi thelium and thereby impair the mucosal barrier to bacteria and their products. In order to obtain an objective measurement of gastrointestinal permeability to large molecules, we measured urinary excretion of [14C]polyvinylpyrrolidone administered p.o.

Journal of Political Ideologies, 1997

This article examines the arguments Lenin employed after the October Revolution in order to justi... more This article examines the arguments Lenin employed after the October Revolution in order to justify party dictatorship over the working class. It challenges the conventional view that Lenin defended constraints on proletarian choice by appealing to the paternalistic vanguard theory set forth in What Is To Be Done? A systematic review of Lenin's revolutionary writings indicates that his legitimation strategy was based instead on an essentialist interpretation of class identity that made it possible to deny proletarian status, and thus democratic rights, to wage‐laborers who opposed Bolshevik rule. It is Lenin's theory of class, therefore, not his theory of the party per se, that is vital for an understanding of his authoritarian politics.

Cancer, Sep 1, 1992

The systemic management of patients with colorectal cancer continues to focus on the use of 5-flu... more The systemic management of patients with colorectal cancer continues to focus on the use of 5-fluorouracil (5-FU). In the setting of metastatic disease, parenteral 5-FU has been shown to be superior to oral 5-FU; however, survival duration seems similar whether such parenteral 5-FU is administered in a "loading," weekly, or continuous infusion manner. The addition of other cytotoxic agents such as semustine, mitomycin C, or cisplatin to 5-FU does not appear to increase the response rate or prolong survival. The results of five randomized trials assessing the value of intraarterial hepatic infusions of 5-FU or floxuridine show that such regional chemotherapy increases the likelihood of hepatic response compared with systemic treatment but has little effect on survival and is associated with significant toxicity. Recent efforts in the management of patients with advanced disease have been directed at optimizing the activity of 5-FU by (1) enhancing the inhibition of DNA synthesis through the concomitant administration of folinic acid; (2) increasing drug incorporation into RNA through pretreatment with methotrexate or phosphonacetyl-L-aspartate; and (3) improving the drug's activity through the synergistic action of alpha-2a-interferon. Although the results of some of these investigations have been promising, only the 5-FU and folinic acid combination consistently has appeared to be superior to single-agent 5-FU. These different approaches to biochemical modulation are being compared in ongoing cooperative group trials.

Journal of Clinical Oncology Official Journal of the American Society of Clinical Oncology, Jul 11, 2011

International Journal of Impact Engineering, Aug 1, 2007

There exists considerable motivation to reduce vehicle weight through the adoption of lightweight... more There exists considerable motivation to reduce vehicle weight through the adoption of lightweight materials, such as aluminium alloys, while maintaining energy absorption and component integrity under crash conditions. The interaction between tube hydroforming and behaviour during crash events was studied using lightweight automotive structural members. Dynamic crush tests were performed on 400 mm length sections of both non-hydroformed and hydroformed EN-AW 5018 aluminium alloy tubes. The force versus crush distance data from 76.2 mm diameter non-hydroformed tubes was compared with results from 76.2 mm square cross-section hydroformed tubes of 2.0 and 3.5 mm initial tube thicknesses. The hydroforming operation was performed using a high-pressure process in which the corner radius of the tube cross-section was varied. Explicit dynamic finite element simulations of the hydroforming and crash events were carried out with particular attention to the transfer of forming history from the hydroforming simulations to the crash models. The values of the tube thickness, work hardening, residual stress, and damage level at the end of the hydroforming simulation were used as the initial state for the crash model. The Gurson-Tvergaard-Needleman constitutive model was used to account for damage based on void nucleation, growth, and coalescence. Numerical predictions of the force versus crush distance response were compared to experimental data. The results have demonstrated that it is important to account for thickness changes and work hardening from previous forming operations, in simulating crash events. The energy absorbing capabilities of the hydroformed aluminium tubes decreased with sharper corner radius due to increased thinning of the material during the hydroforming process. It was found that the simulations slightly over-predicted the mean crush force compared to the experimental data. r

$Research paper thumbnail of Erratum to: Phase 1 study of oral TAS-102 in patients with refractory metastatic colorectal cancer$

Cancer chemotherapy and pharmacology, Jan 20, 2015

Crashworthiness simulations can be useful tools in vehicle design. According to Du Bois , there a... more Crashworthiness simulations can be useful tools in vehicle design. According to Du Bois , there are many factors which affect the reliability of crashworthiness models. Especially, the mesh size and the mapping of forming results into crash models. Few studies have analyzed the mesh size effect with forming results on the crashworthiness of frame components. This paper presents an analysis of crush response of hydroformed aluminium tubes from both experiments and finite element simulations. The predicted crush response for tubes meshed with different mesh sizes for hydroforming with results transferred to the crash simulations will be firstly shown. Predicted mean crush forces will be compared to measured ones. Thereafter, forming results were remapped on a secondary model, having coarser mesh sizes for crush simulations, with the LS-DYNA option called *INCLUDE_STAMPED_PART. Results show that in certain instances, it may be better to use a fine mesh size for the hydroforming models and remap forming results to coarser mesh sizes for crashworthiness models to save computational time. 6th European LS-DYNA Users' Conference 4.178 4.6.2

IEEE Transactions on Aerospace and Navigational Electronics, 1964

such as 60°, may be of advantage. A simple vectorial combination, however, was applied to a singl... more such as 60°, may be of advantage. A simple vectorial combination, however, was applied to a single pattern which already contains an azimuth-dependent phase relation. The dependence of the swing on the distance (resulting swing vs distance) is also plotted in . shows the isophase configuration when two cardioids are used, when two circular fields are used.

$Research paper thumbnail of Phase 1 study of oral TAS-102 in patients with refractory metastatic colorectal cancer$

Cancer chemotherapy and pharmacology, Jan 14, 2015

To evaluate safety of TAS-102 administered twice daily (bid) on days 1-5 and 8-12 of a 4-week cyc... more To evaluate safety of TAS-102 administered twice daily (bid) on days 1-5 and 8-12 of a 4-week cycle, confirm feasibility of the Japanese recommended dose (RD), 35 mg/m(2), in Western patients with metastatic colorectal cancer (mCRC) refractory to standard chemotherapies, and describe preliminary antitumor activity. This open-label, dose-escalation phase 1 study was conducted at four US centers. Patients were enrolled into two sequential cohorts [30 (cohort 1) or 35 mg/m(2)/dose bid (cohort 2)]; dose-limiting toxicities (DLT) were evaluated during cycle 1 in dose-escalation cohorts. At RD, 15 additional patients were enrolled in an expansion cohort. Patients (N = 27) with refractory mCRC received TAS-102; 74 % had received ≥4 prior regimens. DLT was not observed in three patients in cohort 1, and was in one out of nine patients in cohort 2 (grade 3 febrile neutropenia). Therefore, RD was identified as 35 mg/m(2) bid. At RD, fatigue (63 %), gastrointestinal disturbances and nausea (46...

CI, 0.54-0.96) for disease-free survival, 0.74 (95% CI, 0.55-0.99) for recurrence-free survival, ... more CI, 0.54-0.96) for disease-free survival, 0.74 (95% CI, 0.55-0.99) for recurrence-free survival, and 0.75 (95% CI, 0.54-1.05) for overall survival. This reduction in risk of cancer recurrence or death associated with a family history became stronger with an increasing number of affected first-degree relatives. Compared with participants with- out a family history of colorectal cancer, those with 1 affected relative