Programmable Multi-Chip Module

DOEpatents

Kautz, David; Morgenstern, Howard; Blazek, Roy J.

2004-11-16

A multi-chip module comprising a low-temperature co-fired ceramic substrate having a first side on which are mounted active components and a second side on which are mounted passive components, wherein this segregation of components allows for hermetically sealing the active components with a cover while leaving accessible the passive components, and wherein the passive components are secured using a reflow soldering technique and are removable and replaceable so as to make the multi-chip module substantially programmable with regard to the passive components.

Programmable multi-chip module

DOEpatents

Kautz, David; Morgenstern, Howard; Blazek, Roy J.

2004-03-02

A multi-chip module comprising a low-temperature co-fired ceramic substrate having a first side on which are mounted active components and a second side on which are mounted passive components, wherein this segregation of components allows for hermetically sealing the active components with a cover while leaving accessible the passive components, and wherein the passive components are secured using a reflow soldering technique and are removable and replaceable so as to make the multi-chip module substantially programmable with regard to the passive components.

MCM Polarimetric Radiometers for Planar Arrays

NASA Technical Reports Server (NTRS)

Kangaslahti, Pekka; Dawson, Douglas; Gaier, Todd

2007-01-01

A polarimetric radiometer that operates at a frequency of 40 GHz has been designed and built as a prototype of multiple identical units that could be arranged in a planar array for scientific measurements. Such an array is planned for use in studying the cosmic microwave background (CMB). All of the subsystems and components of this polarimetric radiometer are integrated into a single multi-chip module (MCM) of substantially planar geometry. In comparison with traditional designs of polarimetric radiometers, the MCM design is expected to greatly reduce the cost per unit in an array of many such units. The design of the unit is dictated partly by a requirement, in the planned CMB application, to measure the Stokes parameters I, Q, and U of the CMB radiation with high sensitivity. (A complete definition of the Stokes parameters would exceed the scope of this article. In necessarily oversimplified terms, I is a measure of total intensity of radiation, while Q and U are measures of the relationships between the horizontally and vertically polarized components of radiation.) Because the sensitivity of a single polarimeter cannot be increased significantly, the only way to satisfy the high-sensitivity requirement is to make a large array of polarimeters that operate in parallel. The MCM includes contact pins that can be plugged into receptacles on a standard printed-circuit board (PCB). All of the required microwave functionality is implemented within the MCM; any required supporting non-microwave ("back-end") electronic functionality, including the provision of DC bias and control signals, can be implemented by standard PCB techniques. On the way from a microwave antenna to the MCM, the incoming microwave signal passes through an orthomode transducer (OMT), which splits the radiation into an h + i(nu) beam and an h - i(nu) beam (where, using complex-number notation, h denotes the horizontal component, nu denotes the vertical component, and +/-i denotes a +/-90deg phase shift). Each of these beams enters the MCM through one of two WR-22 waveguide input terminals in the lid of the MCM. The h + i(nu0 and h - i(nu) signals are amplified, then fed to a phase-discriminator hybrid designed specifically to fit the predominantly planar character of the MCM geometry and to enable determination of Q and U. The phase-discriminator hybrid generates four outputs, which are detected and used to calculate I, Q, and U.

Spacecraft computer technology at Southwest Research Institute

NASA Technical Reports Server (NTRS)

Shirley, D. J.

1993-01-01

Southwest Research Institute (SwRI) has developed and delivered spacecraft computers for a number of different near-Earth-orbit spacecraft including shuttle experiments and SDIO free-flyer experiments. We describe the evolution of the basic SwRI spacecraft computer design from those weighing in at 20 to 25 lb and using 20 to 30 W to newer models weighing less than 5 lb and using only about 5 W, yet delivering twice the processing throughput. Because of their reduced size, weight, and power, these newer designs are especially applicable to planetary instrument requirements. The basis of our design evolution has been the availability of more powerful processor chip sets and the development of higher density packaging technology, coupled with more aggressive design strategies in incorporating high-density FPGA technology and use of high-density memory chips. In addition to reductions in size, weight, and power, the newer designs also address the necessity of survival in the harsh radiation environment of space. Spurred by participation in such programs as MSTI, LACE, RME, Delta 181, Delta Star, and RADARSAT, our designs have evolved in response to program demands to be small, low-powered units, radiation tolerant enough to be suitable for both Earth-orbit microsats and for planetary instruments. Present designs already include MIL-STD-1750 and Multi-Chip Module (MCM) technology with near-term plans to include RISC processors and higher-density MCM's. Long term plans include development of whole-core processors on one or two MCM's.

Prototype Parts of a Digital Beam-Forming Wide-Band Receiver

NASA Technical Reports Server (NTRS)

Kaplan, Steven B.; Pylov, Sergey V.; Pambianchi, Michael

2003-01-01

Some prototype parts of a digital beamforming (DBF) receiver that would operate at multigigahertz carrier frequencies have been developed. The beam-forming algorithm in a DBF receiver processes signals from multiple antenna elements with appropriate time delays and weighting factors chosen to enhance the reception of signals from a specific direction while suppressing signals from other directions. Such a receiver would be used in the directional reception of weak wideband signals -- for example, spread-spectrum signals from a low-power transmitter on an Earth-orbiting spacecraft or other distant source. The prototype parts include superconducting components on integrated-circuit chips, and a multichip module (MCM), within which the chips are to be packaged and connected via special inter-chip-communication circuits. The design and the underlying principle of operation are based on the use of the rapid single-flux quantum (RSFQ) family of logic circuits to obtain the required processing speed and signal-to-noise ratio. RSFQ circuits are superconducting circuits that exploit the Josephson effect. They are well suited for this application, having been proven to perform well in some circuits at frequencies above 100 GHz. In order to maintain the superconductivity needed for proper functioning of the RSFQ circuits, the MCM must be kept in a cryogenic environment during operation.

Low energy CMOS for space applications

NASA Technical Reports Server (NTRS)

Panwar, Ramesh; Alkalaj, Leon

1992-01-01

The current focus of NASA's space flight programs reflects a new thrust towards smaller, less costly, and more frequent space missions, when compared to missions such as Galileo, Magellan, or Cassini. Recently, the concept of a microspacecraft was proposed. In this concept, a small, compact spacecraft that weighs tens of kilograms performs focused scientific objectives such as imaging. Similarly, a Mars Lander micro-rover project is under study that will allow miniature robots weighing less than seven kilograms to explore the Martian surface. To bring the microspacecraft and microrover ideas to fruition, one will have to leverage compact 3D multi-chip module-based multiprocessors (MCM) technologies. Low energy CMOS will become increasingly important because of the thermodynamic considerations in cooling compact 3D MCM implementations and also from considerations of the power budget for space applications. In this paper, we show how the operating voltage is related to the threshold voltage of the CMOS transistors for accomplishing a task in VLSI with minimal energy. We also derive expressions for the noise margins at the optimal operating point. We then look at a low voltage CMOS (LVCMOS) technology developed at Stanford University which improves the power consumption over conventional CMOS by a couple of orders of magnitude and consider the suitability of the technology for space applications by characterizing its SEU immunity.

Advanced packaging for Integrated Micro-Instruments

NASA Technical Reports Server (NTRS)

Lyke, James L.

1995-01-01

The relationship between packaging, microelectronics, and micro-electrical-mechanical systems (MEMS) is an important one, particularly when the edges of performance boundaries are pressed, as in the case of miniaturized systems. Packaging is a sort of physical backbone that enables the maximum performance of these systems to be realized, and the penalties imposed by conventional packing approaches is particularly limiting for MEMS devices. As such, advanced packaging approaches, such as multi-chip modules (MCM's) have been touted as a true means of electronic 'enablement' for a variety of application domains. Realizing an optimum system of packaging, however, in not as simple as replacing a set of single chip packages with a substrate of interconnections. Research at Phillips Laboratory has turned up a number of integrating options in the two- and three-dimensional rending of miniature systems with physical interconnection structures with intrinsically high performance. Not only do these structures motivate the redesign of integrated circuits (IC's) for lower power, but they possess interesting features that provide a framework for the direct integration of MEMS devices. Cost remains a barrier to the application of MEMS devices, even in space systems. Several innovations are suggested that will result in lower cost and more rapid cycle time. First, the novelty of a 'constant floor plan' MCM which encapsulates a variety of commonly used components into a stockable, easily customized assembly is discussed. Next, the use of low-cost substrates is examined. The anticipated advent of ultra-high density interconnect (UHDI) is suggested as the limit argument of advanced packaging. Finally, the concept of a heterogeneous 3-D MCM system is outlined that allows for the combination of different compatible packaging approaches into a uniformly dense structure that could also include MEMS-based sensors.

Three dimensional, multi-chip module

DOEpatents

Bernhardt, A.F.; Petersen, R.W.

1993-08-31

A plurality of multi-chip modules are stacked and bonded around the perimeter by sold-bump bonds to adjacent modules on, for instance, three sides of the perimeter. The fourth side can be used for coolant distribution, for more interconnect structures, or other features, depending on particular design considerations of the chip set. The multi-chip modules comprise a circuit board, having a planarized interconnect structure formed on a first major surface, and integrated circuit chips bonded to the planarized interconnect surface. Around the periphery of each circuit board, long, narrow dummy chips'' are bonded to the finished circuit board to form a perimeter wall. The wall is higher than any of the chips on the circuit board, so that the flat back surface of the board above will only touch the perimeter wall. Module-to-module interconnect is laser-patterned on the sides of the boards and over the perimeter wall in the same way and at the same time that chip to board interconnect may be laser-patterned.

Three dimensional, multi-chip module

DOEpatents

Bernhardt, Anthony F.; Petersen, Robert W.

1993-01-01

A plurality of multi-chip modules are stacked and bonded around the perimeter by sold-bump bonds to adjacent modules on, for instance, three sides of the perimeter. The fourth side can be used for coolant distribution, for more interconnect structures, or other features, depending on particular design considerations of the chip set. The multi-chip modules comprise a circuit board, having a planarized interconnect structure formed on a first major surface, and integrated circuit chips bonded to the planarized interconnect surface. Around the periphery of each circuit board, long, narrow "dummy chips" are bonded to the finished circuit board to form a perimeter wall. The wall is higher than any of the chips on the circuit board, so that the flat back surface of the board above will only touch the perimeter wall. Module-to-module interconnect is laser-patterned o the sides of the boards and over the perimeter wall in the same way and at the same time that chip to board interconnect may be laser-patterned.

A Novel Silicon Micromachined Integrated MCM Thermal Management System

NASA Technical Reports Server (NTRS)

Kazmierczak, M. J.; Henderson, H. T.; Gerner, F. M.

1997-01-01

"Micromachining" is a chemical means of etching three-dimensional structures, typically in single- crystalline silicon. These techniques are leading toward what is coming to be referred to as MEMS (Micro Electro Mechanical Systems), where in addition to the ordinary two-dimensional (planar) microelectronics, it is possible to build three-dimensional n-ticromotors, electrically- actuated raicrovalves, hydraulic systems and much more on the same microchip. These techniques become possible because of differential etching rates of various crystallographic planes and materials used for semiconductor n-ticrofabfication. The University of Cincinnati group in collaboration with Karl Baker at NASA Lewis were the first to form micro heat pipes in silicon by the above techniques. Current work now in progress using MEMS technology is now directed towards the development of the next generation in MCM (Multi Chip Module) packaging. Here we propose to develop a complete electronic thermal management system which will allow densifica6on in chip stacking by perhaps two orders of magnitude. Furthermore the proposed technique will allow ordinary conu-nercial integrated chips to be utilized. Basically, the new technique involves etching square holes into a silicon substrate and then inserting and bonding commercially available integrated chips into these holes. For example, over a 100 1/4 in. by 1 /4 in. integrated chips can be placed on a 4 in. by 4 in. silicon substrate to form a Multi-Chip Module (MCM). Placing these MCM's in-line within an integrated rack then allows for three-diniensional stacking. Increased miniaturization of microelectronic circuits will lead to very high local heat fluxes. A high performance thermal management system will be specifically designed to remove the generated energy. More specifically, a compact heat exchanger with milli / microchannels will be developed and tested to remove the heat through the back side of this MCM assembly for moderate and high heat flux applications, respectively. The high heat load application of particular interest in mind is the motor controller developed by Martin Marietta for Nasa to control the thruster's directional actuators on space vechicles. Work is also proposed to develop highly advanced and improved porous wick structures for use in advanced heat loops. The porous wick will be micromachined from silicon using MEMS technology, thus permitting far superior control of pore size and pore distribution (over wicks made from sintered n-ietals), which in turn is expected to led to significantly improved heat loop performance.

Novel Techniques for Millimeter-Wave Packages

NASA Technical Reports Server (NTRS)

Herman, Martin I.; Lee, Karen A.; Kolawa, Elzbieta A.; Lowry, Lynn E.; Tulintseff, Ann N.

1995-01-01

A new millimeter-wave package architecture with supporting electrical, mechanical and material science experiment and analysis is presented. This package is well suited for discrete devices, monolithic microwave integrated circuits (MMIC's) and multichip module (MCM) applications. It has low-loss wide-band RF transitions which are necessary to overcome manufacturing tolerances leading to lower per unit cost Potential applications of this new packaging architecture which go beyond the standard requirements of device protection include integration of antennas, compatibility to photonic networks and direct transitions to waveguide systems. Techniques for electromagnetic analysis, thermal control and hermetic sealing were explored. Three dimensional electromagnetic analysis was performed using a finite difference time-domain (FDTD) algorithm and experimentally verified for millimeter-wave package input and output transitions. New multi-material system concepts (AlN, Cu, and diamond thin films) which allow excellent surface finishes to be achieved with enhanced thermal management have been investigated. A new approach utilizing block copolymer coatings was employed to hermetically seal packages which met MIL STD-883.

An introduction to NASA's advanced computing program: Integrated computing systems in advanced multichip modules

NASA Technical Reports Server (NTRS)

Fang, Wai-Chi; Alkalai, Leon

1996-01-01

Recent changes within NASA's space exploration program favor the design, implementation, and operation of low cost, lightweight, small and micro spacecraft with multiple launches per year. In order to meet the future needs of these missions with regard to the use of spacecraft microelectronics, NASA's advanced flight computing (AFC) program is currently considering industrial cooperation and advanced packaging architectures. In relation to this, the AFC program is reviewed, considering the design and implementation of NASA's AFC multichip module.

A CMOS ASIC Design for SiPM Arrays

PubMed Central

Dey, Samrat; Banks, Lushon; Chen, Shaw-Pin; Xu, Wenbin; Lewellen, Thomas K.; Miyaoka, Robert S.; Rudell, Jacques C.

2012-01-01

Our lab has previously reported on novel board-level readout electronics for an 8×8 silicon photomultiplier (SiPM) array featuring row/column summation technique to reduce the hardware requirements for signal processing. We are taking the next step by implementing a monolithic CMOS chip which is based on the row-column architecture. In addition, this paper explores the option of using diagonal summation as well as calibration to compensate for temperature and process variations. Further description of a timing pickoff signal which aligns all of the positioning (spatial channels) pulses in the array is described. The ASIC design is targeted to be scalable with the detector size and flexible to accommodate detectors from different vendors. This paper focuses on circuit implementation issues associated with the design of the ASIC to interface our Phase II MiCES FPGA board with a SiPM array. Moreover, a discussion is provided for strategies to eventually integrate all the analog and mixed-signal electronics with the SiPM, on either a single-silicon substrate or multi-chip module (MCM). PMID:24825923

An application protocol for CAD to CAD transfer of electronic information

NASA Technical Reports Server (NTRS)

Azu, Charles C., Jr.

1993-01-01

The exchange of Computer Aided Design (CAD) information between dissimilar CAD systems is a problem. This is especially true for transferring electronics CAD information such as multi-chip module (MCM), hybrid microcircuit assembly (HMA), and printed circuit board (PCB) designs. Currently, there exists several neutral data formats for transferring electronics CAD information. These include IGES, EDIF, and DXF formats. All these formats have limitations for use in exchanging electronic data. In an attempt to overcome these limitations, the Navy's MicroCIM program implemented a project to transfer hybrid microcircuit design information between dissimilar CAD systems. The IGES (Initial Graphics Exchange Specification) format is used since it is well established within the CAD industry. The goal of the project is to have a complete transfer of microelectronic CAD information, using IGES, without any data loss. An Application Protocol (AP) is being developed to specify how hybrid microcircuit CAD information will be represented by IGES entity constructs. The AP defines which IGES data items are appropriate for describing HMA geometry, connectivity, and processing as well as HMA material characteristics.

Quartz/fused silica chip carriers

NASA Technical Reports Server (NTRS)

1992-01-01

The primary objective of this research and development effort was to develop monolithic microwave integrated circuit (MMIC) packaging which will operate efficiently at millimeter-wave frequencies. The packages incorporated fused silica as the substrate material which was selected due to its favorable electrical properties and potential performance improvement over more conventional materials for Ka-band operation. The first step towards meeting this objective is to develop a package that meets standard mechanical and thermal requirements using fused silica and to be compatible with semiconductor devices operating up to at least 44 GHz. The second step is to modify the package design and add multilayer and multicavity capacity to allow for application specific integrated circuits (ASIC's) to control multiple phase shifters. The final step is to adapt the package design to a phased array module with integral radiating elements. The first task was a continuation of the SBIR Phase 1 work. Phase 1 identified fused silica as a viable substrate material by demonstrating various plating, machining, and adhesion properties. In Phase 2 Task 1, a package was designed and fabricated to validate these findings. Task 2 was to take the next step in packaging and fabricate a multilayer, multichip module (MCM). This package is the predecessor to the phased array module and demonstrates the ability to via fill, circuit print, laminate, and to form vertical interconnects. The final task was to build a phased array module. The radiating elements were to be incorporated into the package instead of connecting to it with wire or ribbon bonds.

Thermal fatigue life evaluation of SnAgCu solder joints in a multi-chip power module

NASA Astrophysics Data System (ADS)

Barbagallo, C.; Malgioglio, G. L.; Petrone, G.; Cammarata, G.

2017-05-01

For power devices, the reliability of thermal fatigue induced by thermal cycling has been prioritized as an important concern. The main target of this work is to apply a numerical procedure to assess the fatigue life for lead-free solder joints, that represent, in general, the weakest part of the electronic modules. Starting from a real multi-chip power module, FE-based models were built-up by considering different conditions in model implementation in order to simulate, from one hand, the worst working condition for the module and, from another one, the module standing into a climatic test room performing thermal cycles. Simulations were carried-out both in steady and transient conditions in order to estimate the module thermal maps, the stress-strain distributions, the effective plastic strain distributions and finally to assess the number of cycles to failure of the constitutive solder layers.

Ultra-Reliable Digital Avionics (URDA) processor

NASA Astrophysics Data System (ADS)

Branstetter, Reagan; Ruszczyk, William; Miville, Frank

1994-10-01

Texas Instruments Incorporated (TI) developed the URDA processor design under contract with the U.S. Air Force Wright Laboratory and the U.S. Army Night Vision and Electro-Sensors Directorate. TI's approach couples advanced packaging solutions with advanced integrated circuit (IC) technology to provide a high-performance (200 MIPS/800 MFLOPS) modular avionics processor module for a wide range of avionics applications. TI's processor design integrates two Ada-programmable, URDA basic processor modules (BPM's) with a JIAWG-compatible PiBus and TMBus on a single F-22 common integrated processor-compatible form-factor SEM-E avionics card. A separate, high-speed (25-MWord/second 32-bit word) input/output bus is provided for sensor data. Each BPM provides a peak throughput of 100 MIPS scalar concurrent with 400-MFLOPS vector processing in a removable multichip module (MCM) mounted to a liquid-flowthrough (LFT) core and interfacing to a processor interface module printed wiring board (PWB). Commercial RISC technology coupled with TI's advanced bipolar complementary metal oxide semiconductor (BiCMOS) application specific integrated circuit (ASIC) and silicon-on-silicon packaging technologies are used to achieve the high performance in a miniaturized package. A Mips R4000-family reduced instruction set computer (RISC) processor and a TI 100-MHz BiCMOS vector coprocessor (VCP) ASIC provide, respectively, the 100 MIPS of a scalar processor throughput and 400 MFLOPS of vector processing throughput for each BPM. The TI Aladdim ASIC chipset was developed on the TI Aladdin Program under contract with the U.S. Army Communications and Electronics Command and was sponsored by the Advanced Research Projects Agency with technical direction from the U.S. Army Night Vision and Electro-Sensors Directorate.

SpaceWire Driver Software for Special DSPs

NASA Technical Reports Server (NTRS)

Clark, Douglas; Lux, James; Nishimoto, Kouji; Lang, Minh

2003-01-01

A computer program provides a high-level C-language interface to electronics circuitry that controls a SpaceWire interface in a system based on a space qualified version of the ADSP-21020 digital signal processor (DSP). SpaceWire is a spacecraft-oriented standard for packet-switching data-communication networks that comprise nodes connected through bidirectional digital serial links that utilize low-voltage differential signaling (LVDS). The software is tailored to the SMCS-332 application-specific integrated circuit (ASIC) (also available as the TSS901E), which provides three highspeed (150 Mbps) serial point-to-point links compliant with the proposed Institute of Electrical and Electronics Engineers (IEEE) Standard 1355.2 and equivalent European Space Agency (ESA) Standard ECSS-E-50-12. In the specific application of this software, the SpaceWire ASIC was combined with the DSP processor, memory, and control logic in a Multi-Chip Module DSP (MCM-DSP). The software is a collection of low-level driver routines that provide a simple message-passing application programming interface (API) for software running on the DSP. Routines are provided for interrupt-driven access to the two styles of interface provided by the SMCS: (1) the "word at a time" conventional host interface (HOCI); and (2) a higher performance "dual port memory" style interface (COMI).

Structure and regulatory role of the C-terminal winged helix domain of the archaeal minichromosome maintenance complex

PubMed Central

Wiedemann, Christoph; Szambowska, Anna; Häfner, Sabine; Ohlenschläger, Oliver; Gührs, Karl-Heinz; Görlach, Matthias

2015-01-01

The minichromosome maintenance complex (MCM) represents the replicative DNA helicase both in eukaryotes and archaea. Here, we describe the solution structure of the C-terminal domains of the archaeal MCMs of Sulfolobus solfataricus (Sso) and Methanothermobacter thermautotrophicus (Mth). Those domains consist of a structurally conserved truncated winged helix (WH) domain lacking the two typical ‘wings’ of canonical WH domains. A less conserved N-terminal extension links this WH module to the MCM AAA+ domain forming the ATPase center. In the Sso MCM this linker contains a short α-helical element. Using Sso MCM mutants, including chimeric constructs containing Mth C-terminal domain elements, we show that the ATPase and helicase activity of the Sso MCM is significantly modulated by the short α-helical linker element and by N-terminal residues of the first α-helix of the truncated WH module. Finally, based on our structural and functional data, we present a docking-derived model of the Sso MCM, which implies an allosteric control of the ATPase center by the C-terminal domain. PMID:25712103

Tunneling Accelerometer Multichip Module

NASA Technical Reports Server (NTRS)

Boyadzhyan, V. V.; Choma, J., Jr.

1998-01-01

This paper summarizes and reports a radiation hardened Spacecraft Integrated Sensor/Circut Technology that has been delivered for flight applications to be flown on board STRV-2 (Space Technology Research Vehicle-2).

Non-essential MCM-related proteins mediate a response to DNA damage in the archaeon Methanococcus maripaludis.

PubMed

Walters, Alison D; Chong, James P J

2017-05-01

The single minichromosome maintenance (MCM) protein found in most archaea has been widely studied as a simplified model for the MCM complex that forms the catalytic core of the eukaryotic replicative helicase. Organisms of the order Methanococcales are unusual in possessing multiple MCM homologues. The Methanococcus maripaludis S2 genome encodes four MCM homologues, McmA-McmD. DNA helicase assays reveal that the unwinding activity of the three MCM-like proteins is highly variable despite sequence similarities and suggests additional motifs that influence MCM function are yet to be identified. While the gene encoding McmA could not be deleted, strains harbouring individual deletions of genes encoding each of the other MCMs display phenotypes consistent with these proteins modulating DNA damage responses. M. maripaludis S2 is the first archaeon in which MCM proteins have been shown to influence the DNA damage response.

Compact VLSI neural computer integrated with active pixel sensor for real-time ATR applications

NASA Astrophysics Data System (ADS)

Fang, Wai-Chi; Udomkesmalee, Gabriel; Alkalai, Leon

1997-04-01

A compact VLSI neural computer integrated with an active pixel sensor has been under development to mimic what is inherent in biological vision systems. This electronic eye- brain computer is targeted for real-time machine vision applications which require both high-bandwidth communication and high-performance computing for data sensing, synergy of multiple types of sensory information, feature extraction, target detection, target recognition, and control functions. The neural computer is based on a composite structure which combines Annealing Cellular Neural Network (ACNN) and Hierarchical Self-Organization Neural Network (HSONN). The ACNN architecture is a programmable and scalable multi- dimensional array of annealing neurons which are locally connected with their local neurons. Meanwhile, the HSONN adopts a hierarchical structure with nonlinear basis functions. The ACNN+HSONN neural computer is effectively designed to perform programmable functions for machine vision processing in all levels with its embedded host processor. It provides a two order-of-magnitude increase in computation power over the state-of-the-art microcomputer and DSP microelectronics. A compact current-mode VLSI design feasibility of the ACNN+HSONN neural computer is demonstrated by a 3D 16X8X9-cube neural processor chip design in a 2-micrometers CMOS technology. Integration of this neural computer as one slice of a 4'X4' multichip module into the 3D MCM based avionics architecture for NASA's New Millennium Program is also described.

A Digital Lock-In Amplifier for Use at Temperatures of up to 200 °C

PubMed Central

Cheng, Jingjing; Xu, Yingjun; Wu, Lei; Wang, Guangwei

2016-01-01

Weak voltage signals cannot be reliably measured using currently available logging tools when these tools are subject to high-temperature (up to 200 °C) environments for prolonged periods. In this paper, we present a digital lock-in amplifier (DLIA) capable of operating at temperatures of up to 200 °C. The DLIA contains a low-noise instrument amplifier and signal acquisition and the corresponding signal processing electronics. The high-temperature stability of the DLIA is achieved by designing system-in-package (SiP) and multi-chip module (MCM) components with low thermal resistances. An effective look-up-table (LUT) method was developed for the lock-in amplifier algorithm, to decrease the complexity of the calculations and generate less heat than the traditional way. The performance of the design was tested by determining the linearity, gain, Q value, and frequency characteristic of the DLIA between 25 and 200 °C. The maximal nonlinear error in the linearity of the DLIA working at 200 °C was about 1.736% when the equivalent input was a sine wave signal with an amplitude of between 94.8 and 1896.0 nV and a frequency of 800 kHz. The tests showed that the DLIA proposed could work effectively in high-temperature environments up to 200 °C. PMID:27845710

NANOSPACE-1: the Impacts of the First Swedish Nanosatellite on Spacecraft Architecture and Design

NASA Astrophysics Data System (ADS)

Bruhn, F.; Köhler, J.; Stenmark, L.

2002-01-01

NanoSpace-1 (NS-1), due to be launched in late 2003 or early 2004 will test highly advanced Micro Systems Technology (MST) for space applications. These devices are highly miniaturized and optimized complete systems in the sense that all parts of the system are processed with MST and integrated as Multifunctional Microsystems (MMS). The very high level of miniaturization and multifunctionallity in the MMS, will enable easier access to space for nanosatellites to perform better scientific research. This new class of high performing small satellites will open areas for research that before only could be done with much larger and costly satellites. Many institutions, universities, and small countries will benefit greatly as that nanosatellites become more capable per mass unit and volume unit than other spacecraft. These new MMS/MST satellites will provide the ground for a better and less expensive exploration of space. NS-1 will be the first high-performing nanosatellite by using MST/MMS to many subsystems and modules. The whole spacecraft will be built around MMS and will include multifunctional 3D-Multi Chip Modules (3D-MCM), a 3D thin film solar sensor, thin film coating for passive thermal control, variable emittance panels, microwave MEMS patch antennas, micromechanical thermal switches, thin film solar cells with record high efficiency and finally silicon as multifunctional active structure elements. The complete spacecraft will weigh about 7 kg and have dimensions of 32x32x15 cm. The overall mission for NS-1 is to test the new technologies mentioned above, and to collect experiences in the field of MMS architecture. However, new technologies in itself will not take us to a new generation spacecraft. Deeply integrated within the structure of the NanoSpace program are new system designs and multifunctional systems thinking. Distributed and autonomous subsystems are very important when incorporating new technologies with high redundancy. Autonomous systems also reduce the complexity of the overall spacecraft design since many functions can be placed in multifunctional multichip modules. This implies an increase of the complexity at the spacecraft subsystem level. NanoSpace-1 will test several new autonomous, distributed, and miniaturized multifunctional systems, including large memories modules, house keeping modules, RF- MEMS, and power conditioning modules. The MMS concept comprises several features, for instance, all 3D-multi chip modules are part of the spacecraft structure itself. The use of 3D-MCM modules as a large part of the spacecraft hull is a direct application of MMS thinking; the modules are load taking structure elements, and also contain many subsystems of the spacecraft. The MMS thinking is illustrated by the RF-MEMS 3D-MCM module. All other modules will be further presented in the paper. The RF-MEMS module comprises micro strips, patch-antennas, solid state power amplifiers, thermal control, micromechanical switches, power conditioning, radiation shields, and command interfaces. The size of the RF-module is 68x68x5 mm and has a weight of less than 70g. The module is designed to handle different frequencies, only by changing the top wafers and the mixer chip. MST and MMS integrated modules pose at least two major challenges compared to conventional technology. First, the processes cannot be changed half way to the product. Any substantial change in the process will almost certainly require a complete redesign of the whole system. Secondly, qualification and product assurance becomes more important since the processes in MMS tend to be long and complicated. The Ångström Space Technology Centre (ÅSTC) is a center for development of Micro Systems Technologies (MST) for Space Applications at the department of Materials Science at Uppsala University in Sweden. The center is now taking the next step in the ongoing Nanosatellite program, called the NanoSpace program. Backed by funding from the Swedish National Space Board (SNSB), the European Space Agency (ESA), and the European Commission (EC), the ÅSTC will begin developing nanosatellites to demonstrate the next generation spacecraft. The Nanosatellite program is built around a launch every 2nd year to test, verify and qualify new MST technologies for space. The Nanosatellite effort is a solid and well founded program with a backbone of technology research and Multifunctional Microsystems (MMS) thinking.

Two-Stage, 90-GHz, Low-Noise Amplifier

NASA Technical Reports Server (NTRS)

Samoska, Lorene A.; Gaier, Todd C.; Xenos, Stephanie; Soria, Mary M.; Kangaslahti, Pekka P.; Cleary, Kieran A.; Ferreira, Linda; Lai, Richard; Mei, Xiaobing

2010-01-01

A device has been developed for coherent detection of the polarization of the cosmic microwave background (CMB). A two-stage amplifier has been designed that covers 75-110 GHz. The device uses the emerging 35-nm InP HEMT technology recently developed at Northrop Grumman Corporation primarily for use at higher frequencies. The amplifier has more than 18 dB gain and less than 35 K noise figure across the band. These devices have noise less than 30 K at 100 GHz. The development started with design activities at JPL, as well as characterization of multichip modules using existing InP. Following processing, a test campaign was carried out using single-chip modules at 100 GHz. Successful development of the chips will lead to development of multichip modules, with simultaneous Q and U Stokes parameter detection. This MMIC (monolithic microwave integrated circuit) amplifier takes advantage of performance improvements intended for higher frequencies, but in this innovation are applied at 90 GHz. The large amount of available gain ultimately leads to lower possible noise performance at 90 GHz.

Interpreter composition issues in the formal verification of a processor-memory module

NASA Technical Reports Server (NTRS)

Fura, David A.; Cohen, Gerald C.

1994-01-01

This report describes interpreter composition techniques suitable for the formal specification and verification of a processor-memory module using the HOL theorem proving system. The processor-memory module is a multichip subsystem within a fault-tolerant embedded system under development within the Boeing Defense and Space Group. Modeling and verification methods were developed that permit provably secure composition at the transaction-level of specification, significantly reducing the complexity of the hierarchical verification of the system.

Technology transfer of military space microprocessor developments

NASA Astrophysics Data System (ADS)

Gorden, C.; King, D.; Byington, L.; Lanza, D.

1999-01-01

Over the past 13 years the Air Force Research Laboratory (AFRL) has led the development of microprocessors and computers for USAF space and strategic missile applications. As a result of these Air Force development programs, advanced computer technology is available for use by civil and commercial space customers as well. The Generic VHSIC Spaceborne Computer (GVSC) program began in 1985 at AFRL to fulfill a deficiency in the availability of space-qualified data and control processors. GVSC developed a radiation hardened multi-chip version of the 16-bit, Mil-Std 1750A microprocessor. The follow-on to GVSC, the Advanced Spaceborne Computer Module (ASCM) program, was initiated by AFRL to establish two industrial sources for complete, radiation-hardened 16-bit and 32-bit computers and microelectronic components. Development of the Control Processor Module (CPM), the first of two ASCM contract phases, concluded in 1994 with the availability of two sources for space-qualified, 16-bit Mil-Std-1750A computers, cards, multi-chip modules, and integrated circuits. The second phase of the program, the Advanced Technology Insertion Module (ATIM), was completed in December 1997. ATIM developed two single board computers based on 32-bit reduced instruction set computer (RISC) processors. GVSC, CPM, and ATIM technologies are flying or baselined into the majority of today's DoD, NASA, and commercial satellite systems.

The Fission Yeast Minichromosome Maintenance (MCM)-binding Protein (MCM-BP), Mcb1, Regulates MCM Function during Prereplicative Complex Formation in DNA Replication*

PubMed Central

Santosa, Venny; Martha, Sabrina; Hirose, Noriaki; Tanaka, Katsunori

2013-01-01

The minichromosome maintenance (MCM) complex is a replicative helicase, which is essential for chromosome DNA replication. In recent years, the identification of a novel MCM-binding protein (MCM-BP) in most eukaryotes has led to numerous studies investigating its function and its relationship to the MCM complex. However, the mechanisms by which MCM-BP functions and associates with MCM complexes are not well understood; in addition, the functional role of MCM-BP remains controversial and may vary between model organisms. The present study aims to elucidate the nature and biological function of the MCM-BP ortholog, Mcb1, in fission yeast. The Mcb1 protein continuously interacts with MCM proteins during the cell cycle in vivo and can interact with any individual MCM subunit in vitro. To understand the detailed characteristics of mcb1+, two temperature-sensitive mcb1 gene mutants (mcb1ts) were isolated. Extensive genetic analysis showed that the mcb1ts mutants were suppressed by a mcm5+ multicopy plasmid and displayed synthetic defects with many S-phase-related gene mutants. Moreover, cyclin-dependent kinase modulation by Cig2 repression or Rum1 overproduction suppressed the mcb1ts mutants, suggesting the involvement of Mcb1 in pre-RC formation during DNA replication. These data are consistent with the observation that Mcm7 loading onto replication origins is reduced and S-phase progression is delayed in mcb1ts mutants. Furthermore, the mcb1ts mutation led to the redistribution of MCM subunits to the cytoplasm, and this redistribution was dependent on an active nuclear export system. These results strongly suggest that Mcb1 promotes efficient pre-RC formation during DNA replication by regulating the MCM complex. PMID:23322785

The fission yeast minichromosome maintenance (MCM)-binding protein (MCM-BP), Mcb1, regulates MCM function during prereplicative complex formation in DNA replication.

PubMed

Santosa, Venny; Martha, Sabrina; Hirose, Noriaki; Tanaka, Katsunori

2013-03-08

The minichromosome maintenance (MCM) complex is a replicative helicase, which is essential for chromosome DNA replication. In recent years, the identification of a novel MCM-binding protein (MCM-BP) in most eukaryotes has led to numerous studies investigating its function and its relationship to the MCM complex. However, the mechanisms by which MCM-BP functions and associates with MCM complexes are not well understood; in addition, the functional role of MCM-BP remains controversial and may vary between model organisms. The present study aims to elucidate the nature and biological function of the MCM-BP ortholog, Mcb1, in fission yeast. The Mcb1 protein continuously interacts with MCM proteins during the cell cycle in vivo and can interact with any individual MCM subunit in vitro. To understand the detailed characteristics of mcb1(+), two temperature-sensitive mcb1 gene mutants (mcb1(ts)) were isolated. Extensive genetic analysis showed that the mcb1(ts) mutants were suppressed by a mcm5(+) multicopy plasmid and displayed synthetic defects with many S-phase-related gene mutants. Moreover, cyclin-dependent kinase modulation by Cig2 repression or Rum1 overproduction suppressed the mcb1(ts) mutants, suggesting the involvement of Mcb1 in pre-RC formation during DNA replication. These data are consistent with the observation that Mcm7 loading onto replication origins is reduced and S-phase progression is delayed in mcb1(ts) mutants. Furthermore, the mcb1(ts) mutation led to the redistribution of MCM subunits to the cytoplasm, and this redistribution was dependent on an active nuclear export system. These results strongly suggest that Mcb1 promotes efficient pre-RC formation during DNA replication by regulating the MCM complex.

Materials Research for GHz Multi-Chip Modules

DTIC Science & Technology

1993-09-30

Publications: Laursen, K., Hertling, D., Berry, N., Bidstrup, S.A., Kohl, P., and Arroz , A., "Measurement of the Electrical Properties of Hligh Performance...Materials, Fall 1992. Herding, D.R., Laursen, K., Bidstrup, S.A., Kohl, P.A., Arroz , G.S.., "Measurement of the Electrical Properties of High

Interleukin 10 is an essential modulator of mucoid metaplasia in a mouse otitis media model

PubMed Central

Tsuchiya, Katsuyuki; Komori, Masahiro; Zheng, Qing Yin; Ferrieri, Patricia; Lin, Jizhen

2009-01-01

Inflammatory cytokines are involved in the development of mucus cell metaplasia/hyperplasia (MCM) in otitis media (OM). However, which cytokines play an essential role in MCM OM is not clear at the moment. In this study, we hypothesized that interleukin-10 (IL-10) played an indispensable role in MCM of bacterial OM and used IL-10 knockout mice to test this hypothesis. In wild-type mice, both S. pneumoniae and H. influenzae triggered the development of MCM in the middle ear mucosa. In IL-10 knockout mice, the number of goblet cells and mucin-producing cells in the middle ear was significantly reduced after bacterial middle ear infection compared with that in wild-type mice. We, therefore, concluded that IL-10 plays an essential role in MCM of bacterial OM. IL-10 is a potential target for the treatment of MCM in OM. PMID:18771082

Thin-film decoupling capacitors for multi-chip modules

NASA Astrophysics Data System (ADS)

Dimos, D.; Lockwood, S. J.; Schwartz, R. W.; Rogers, M. S.

Thin-film decoupling capacitors based on ferroelectric lead lanthanum zirconate titanate (PLZT) films are being developed for use in advanced packages, such as multi-chip modules. These thin-film decoupling capacitors are intended to replace multi-layer ceramic capacitors for certain applications, since they can be more fully integrated into the packaging architecture. The increased integration that can be achieved should lead to decreased package volume and improved high-speed performance, due to a decrease in interconnect inductance. PLZT films are fabricated by spin coating using metal carboxylate/alkoxide solutions. These films exhibit very high dielectric constants ((var epsilon) greater than or equal to 900), low dielectric losses (tan(delta) = 0.01), excellent insulation resistances (rho greater than 10(exp 13) (Omega)-cm at 125 C), and good breakdown field strengths (E(sub B) = 900 kV/cm). For integrated circuit applications, the PLZT dielectric is less than 1 micron thick, which results in a large capacitance/area (8-9 nF/sq mm). The thin-film geometry and processing conditions also make these capacitors suitable for direct incorporation onto integrated circuits and for packages that require embedded components.

The Helicase Activity of Hyperthermophilic Archaeal MCM is Enhanced at High Temperatures by Lysine Methylation.

PubMed

Xia, Yisui; Niu, Yanling; Cui, Jiamin; Fu, Yang; Chen, Xiaojiang S; Lou, Huiqiang; Cao, Qinhong

2015-01-01

Lysine methylation and methyltransferases are widespread in the third domain of life, archaea. Nevertheless, the effects of methylation on archaeal proteins wait to be defined. Here, we report that recombinant sisMCM, an archaeal homolog of Mcm2-7 eukaryotic replicative helicase, is methylated by aKMT4 in vitro. Mono-methylation of these lysine residues occurs coincidently in the endogenous sisMCM protein purified from the hyperthermophilic Sulfolobus islandicus cells as indicated by mass spectra. The helicase activity of mini-chromosome maintenance (MCM) is stimulated by methylation, particularly at temperatures over 70°C. The methylated MCM shows optimal DNA unwinding activity after heat-treatment between 76 and 82°C, which correlates well with the typical growth temperatures of hyperthermophilic Sulfolobus. After methylation, the half life of MCM helicase is dramatically extended at 80°C. The methylated sites are located on the accessible protein surface, which might modulate the intra- and inter- molecular interactions through changing the hydrophobicity and surface charge. Furthermore, the methylation-mimic mutants of MCM show heat resistance helicase activity comparable to the methylated MCM. These data provide the biochemical evidence that posttranslational modifications such as methylation may enhance kinetic stability of proteins under the elevated growth temperatures of hyperthermophilic archaea.

The Helicase Activity of Hyperthermophilic Archaeal MCM is Enhanced at High Temperatures by Lysine Methylation

PubMed Central

Xia, Yisui; Niu, Yanling; Cui, Jiamin; Fu, Yang; Chen, Xiaojiang S.; Lou, Huiqiang; Cao, Qinhong

2015-01-01

Lysine methylation and methyltransferases are widespread in the third domain of life, archaea. Nevertheless, the effects of methylation on archaeal proteins wait to be defined. Here, we report that recombinant sisMCM, an archaeal homolog of Mcm2-7 eukaryotic replicative helicase, is methylated by aKMT4 in vitro. Mono-methylation of these lysine residues occurs coincidently in the endogenous sisMCM protein purified from the hyperthermophilic Sulfolobus islandicus cells as indicated by mass spectra. The helicase activity of mini-chromosome maintenance (MCM) is stimulated by methylation, particularly at temperatures over 70°C. The methylated MCM shows optimal DNA unwinding activity after heat-treatment between 76 and 82°C, which correlates well with the typical growth temperatures of hyperthermophilic Sulfolobus. After methylation, the half life of MCM helicase is dramatically extended at 80°C. The methylated sites are located on the accessible protein surface, which might modulate the intra- and inter- molecular interactions through changing the hydrophobicity and surface charge. Furthermore, the methylation-mimic mutants of MCM show heat resistance helicase activity comparable to the methylated MCM. These data provide the biochemical evidence that posttranslational modifications such as methylation may enhance kinetic stability of proteins under the elevated growth temperatures of hyperthermophilic archaea. PMID:26617586

The Use of Metal Filled Via Holes for Improving Isolation in LTCC RF and Wireless Multichip Packages

NASA Technical Reports Server (NTRS)

Ponchak, George E.; Chun, Donghoon; Yook, Jong-Gwan; Katehi, Linda P. B.

1999-01-01

LTCC MCMs (Low Temperature Cofired Ceramic MultiChip Module) for RF and wireless systems often use metal filled via holes to improve isolation between the stripline and microstrip interconnects. In this paper, results from a 3D-FEM electromagnetic characterization of microstrip and stripline interconnects with metal filled via fences for isolation are presented. It is shown that placement of a via hole fence closer than three times the substrate height to the transmission lines increases radiation and coupling. Radiation loss and reflections are increased when a short via fence is used in areas suspected of having high radiation. Also, via posts should not be separated by more than three times the substrate height for low radiation loss, coupling, and suppression of higher order modes in a package.

Mechanism of Archaeal MCM Helicase Recruitment to DNA Replication Origins

PubMed Central

Samson, Rachel Y.; Abeyrathne, Priyanka D.; Bell, Stephen D.

2015-01-01

Summary Cellular DNA replication origins direct the recruitment of replicative helicases via the action of initiator proteins belonging to the AAA+ superfamily of ATPases. Archaea have a simplified subset of the eukaryotic DNA replication machinery proteins and possess initiators that appear ancestral to both eukaryotic Orc1 and Cdc6. We have reconstituted origin-dependent recruitment of the homohexameric archaeal MCM in vitro with purified recombinant proteins. Using this system, we reveal that archaeal Orc1-1 fulfills both Orc1 and Cdc6 functions by binding to a replication origin and directly recruiting MCM helicase. We identify the interaction interface between these proteins and reveal how ATP binding by Orc1-1 modulates recruitment of MCM. Additionally, we provide evidence that an open-ring form of the archaeal MCM homohexamer is loaded at origins. PMID:26725007

Low power signal processing research at Stanford

NASA Technical Reports Server (NTRS)

Burr, J.; Williamson, P. R.; Peterson, A.

1991-01-01

This paper gives an overview of the research being conducted at Stanford University's Space, Telecommunications, and Radioscience Laboratory in the area of low energy computation. It discusses the work we are doing in large scale digital VLSI neural networks, interleaved processor and pipelined memory architectures, energy estimation and optimization, multichip module packaging, and low voltage digital logic.

Ultra-thin silicon (UTSi) on insulator CMOS transceiver and time-division multiplexed switch chips for smart pixel integration

NASA Astrophysics Data System (ADS)

Zhang, Liping; Sawchuk, Alexander A.

2001-12-01

We describe the design, fabrication and functionality of two different 0.5 micron CMOS optoelectronic integrated circuit (OEIC) chips based on the Peregrine Semiconductor Ultra-Thin Silicon on insulator technology. The Peregrine UTSi silicon- on-sapphire (SOS) technology is a member of the silicon-on- insulator (SOI) family. The low-loss synthetic sapphire substrate is optically transparent and has good thermal conductivity and coefficient of thermal expansion properties, which meet the requirements for flip-chip bonding of VCSELs and other optoelectronic input-output components. One chip contains transceiver and network components, including four channel high-speed CMOS transceiver modules, pseudo-random bit stream (PRBS) generators, a voltage controlled oscillator (VCO) and other test circuits. The transceiver chips can operate in both self-testing mode and networking mode. An on- chip clock and true-single-phase-clock (TSPC) D-flip-flop have been designed to generate a PRBS at over 2.5 Gb/s for the high-speed transceiver arrays to operate in self-testing mode. In the networking mode, an even number of transceiver chips forms a ring network through free-space or fiber ribbon interconnections. The second chip contains four channel optical time-division multiplex (TDM) switches, optical transceiver arrays, an active pixel detector and additional test devices. The eventual applications of these chips will require monolithic OEICs with integrated optical input and output. After fabrication and testing, the CMOS transceiver array dies will be packaged with 850 nm vertical cavity surface emitting lasers (VCSELs), and metal-semiconductor- metal (MSM) or GaAs p-i-n detector die arrays to achieve high- speed optical interconnections. The hybrid technique could be either wire bonding or flip-chip bonding of the CMOS SOS smart-pixel arrays with arrays of VCSELs and photodetectors onto an optoelectronic chip carrier as a multi-chip module (MCM).

Ultra low power CMOS technology

NASA Technical Reports Server (NTRS)

Burr, J.; Peterson, A.

1991-01-01

This paper discusses the motivation, opportunities, and problems associated with implementing digital logic at very low voltages, including the challenge of making use of the available real estate in 3D multichip modules, energy requirements of very large neural networks, energy optimization metrics and their impact on system design, modeling problems, circuit design constraints, possible fabrication process modifications to improve performance, and barriers to practical implementation.

Advanced Interconnect Roadmap for Space Applications

NASA Technical Reports Server (NTRS)

Galbraith, Lissa

1999-01-01

This paper presents the NASA electronic parts and packaging program for space applications. The topics include: 1) Forecasts; 2) Technology Challenges; 3) Research Directions; 4) Research Directions for Chip on Board (COB); 5) Research Directions for HDPs: Multichip Modules (MCMs); 6) Research Directions for Microelectromechanical systems (MEMS); 7) Research Directions for Photonics; and 8) Research Directions for Materials. This paper is presented in viewgraph form.

Cryo-EM structures of the eukaryotic replicative helicase bound to a translocation substrate

NASA Astrophysics Data System (ADS)

Abid Ali, Ferdos; Renault, Ludovic; Gannon, Julian; Gahlon, Hailey L.; Kotecha, Abhay; Zhou, Jin Chuan; Rueda, David; Costa, Alessandro

2016-02-01

The Cdc45-MCM-GINS (CMG) helicase unwinds DNA during the elongation step of eukaryotic genome duplication and this process depends on the MCM ATPase function. Whether CMG translocation occurs on single- or double-stranded DNA and how ATP hydrolysis drives DNA unwinding remain open questions. Here we use cryo-electron microscopy to describe two subnanometre resolution structures of the CMG helicase trapped on a DNA fork. In the predominant state, the ring-shaped C-terminal ATPase of MCM is compact and contacts single-stranded DNA, via a set of pre-sensor 1 hairpins that spiral around the translocation substrate. In the second state, the ATPase module is relaxed and apparently substrate free, while DNA intimately contacts the downstream amino-terminal tier of the MCM motor ring. These results, supported by single-molecule FRET measurements, lead us to suggest a replication fork unwinding mechanism whereby the N-terminal and AAA+ tiers of the MCM work in concert to translocate on single-stranded DNA.

Archaeal MCM has separable processivity, substrate choice and helicase domains

PubMed Central

Barry, Elizabeth R.; McGeoch, Adam T.; Kelman, Zvi; Bell, Stephen D.

2007-01-01

The mini-chromosome maintenance (MCM) complex is the principal candidate for the replicative helicase of archaea and eukaryotes. Here, we describe a functional dissection of the roles of the three principal structural modules of the homomultimeric MCM of the hyperthermophilic archaeon Sulfolobus solfataricus. Our results include the first analysis of the central AAA+ domain in isolation. This domain possesses ATPase and helicase activity, defining this as the minimal helicase domain. Reconstitution experiments show that the helicase activity of the AAA+ domain can be stimulated by addition of the isolated N-terminal half in trans. Addition of the N-terminus influences both the processivity of the helicase and the choice of substrate that can be melted by the ATPase domain. The degenerate helix-turn-helix domain at the C-terminus of MCM exerts a negative effect on the helicase activity of the complex. These results provide the first evidence for extensive regulatory inter-domain communication within the MCM complex. PMID:17259218

Experimental Study on Active Cooling Systems Used for Thermal Management of High-Power Multichip Light-Emitting Diodes

PubMed Central

2014-01-01

The objective of this study was to develop suitable cooling systems for high-power multichip LEDs. To this end, three different active cooling systems were investigated to control the heat generated by the powering of high-power multichip LEDs in two different configurations (30 and 2 × 15 W). The following cooling systems were used in the study: an integrated multi-fin heat sink design with a fan, a cooling system with a thermoelectric cooler (TEC), and a heat pipe cooling device. According to the results, all three systems were observed to be sufficient for cooling high-power LEDs. Furthermore, it was observed that the integrated multifin heat sink design with a fan was the most efficient cooling system for a 30 W high-power multichip LED. The cooling system with a TEC and 46 W input power was the most efficient cooling system for 2 × 15 W high-power multichip LEDs. PMID:25162058

Abnormally high expression of POLD1, MCM2, and PLK4 promotes relapse of acute lymphoblastic leukemia.

PubMed

Li, Sheng; Wang, Chengzhong; Wang, Weikai; Liu, Weidong; Zhang, Guiqin

2018-05-01

This study aimed to explore the underlying mechanism of relapsed acute lymphoblastic leukemia (ALL).Datasets of GSE28460 and GSE18497 were downloaded from Gene Expression Omnibus (GEO). Differentially expressed genes (DEGs) between diagnostic and relapsed ALL samples were identified using Limma package in R, and a Venn diagram was drawn. Next, functional enrichment analyses of co-regulated DEGs were performed. Based on the String database, protein-protein interaction network and module analyses were also conducted. Moreover, transcription factors and miRNAs targeting co-regulated DEGs were predicted using the WebGestalt online tool.A total of 71 co-regulated DEGs were identified, including 56 co-upregulated genes and 15 co-downregulated genes. Functional enrichment analyses showed that upregulated DEGs were significantly enriched in the cell cycle, and DNA replication, and repair related pathways. POLD1, MCM2, and PLK4 were hub proteins in both protein-protein interaction network and module, and might be potential targets of E2F. Additionally, POLD1 and MCM2 were found to be regulated by miR-520H via E2F1.High expression of POLD1, MCM2, and PLK4 might play positive roles in the recurrence of ALL, and could serve as potential therapeutic targets for the treatment of relapsed ALL.

T/R Multi-Chip MMIC Modules for 150 GHz

NASA Technical Reports Server (NTRS)

Samoska, Lorene A.; Pukala, David M.; Soria, Mary M.; Sadowy, Gregory A.

2009-01-01

Modules containing multiple monolithic microwave integrated-circuit (MMIC) chips have been built as prototypes of transmitting/receiving (T/R) modules for millimeter-wavelength radar systems, including phased-array radar systems to be used for diverse purposes that could include guidance and avoidance of hazards for landing spacecraft, imaging systems for detecting hidden weapons, and hazard-avoidance systems for automobiles. Whereas prior landing radar systems have operated at frequencies around 35 GHz, the integrated circuits in this module operate in a frequency band centered at about 150 GHz. The higher frequency (and, hence, shorter wavelength), is expected to make it possible to obtain finer spatial resolution while also using smaller antennas and thereby reducing the sizes and masses of the affected systems.

Coherent light squeezing states within a modified microring system

NASA Astrophysics Data System (ADS)

Ali, J.; Pornsuwancharoen, N.; Youplao, P.; Aziz, M. S.; Amiri, I. S.; Chaiwong, K.; Chiangga, S.; Singh, G.; Yupapin, P.

2018-06-01

We have proposed the simple method of the squeezed light generation in the modified microring resonator, which is known as the microring conjugate mirror (MCM). When the monochromatic light is input into the MCM, the general form of the squeezed coherent states for a quantum harmonic oscillator can be generated by controlling the additional two side rings, which are the phase modulators. By using the graphical method called the Optiwave program, the coherent squeezed states of coherent light within an MCM can be obtained and interpreted as the amplitude, phase, quadrature and photon number-squeezed states. This method has shown potentials for microring related device design, which can be used before practical applications.

Update on Development of SiC Multi-Chip Power Modules

NASA Technical Reports Server (NTRS)

Lostetter, Alexander; Cilio, Edgar; Mitchell, Gavin; Schupbach, Roberto

2008-01-01

Progress has been made in a continuing effort to develop multi-chip power modules (SiC MCPMs). This effort at an earlier stage was reported in 'SiC Multi-Chip Power Modules as Power-System Building Blocks' (LEW-18008-1), NASA Tech Briefs, Vol. 31, No. 2 (February 2007), page 28. The following recapitulation of information from the cited prior article is prerequisite to a meaningful summary of the progress made since then: 1) SiC MCPMs are, more specifically, electronic power-supply modules containing multiple silicon carbide power integrated-circuit chips and silicon-on-insulator (SOI) control integrated-circuit chips. SiC MCPMs are being developed as building blocks of advanced expandable, reconfigurable, fault-tolerant power-supply systems. Exploiting the ability of SiC semiconductor devices to operate at temperatures, breakdown voltages, and current densities significantly greater than those of conventional Si devices, the designs of SiC MCPMs and of systems comprising multiple SiC MCPMs are expected to afford a greater degree of miniaturization through stacking of modules with reduced requirements for heat sinking; 2) The stacked SiC MCPMs in a given system can be electrically connected in series, parallel, or a series/parallel combination to increase the overall power-handling capability of the system. In addition to power connections, the modules have communication connections. The SOI controllers in the modules communicate with each other as nodes of a decentralized control network, in which no single controller exerts overall command of the system. Control functions effected via the network include synchronization of switching of power devices and rapid reconfiguration of power connections to enable the power system to continue to supply power to a load in the event of failure of one of the modules; and, 3) In addition to serving as building blocks of reliable power-supply systems, SiC MCPMs could be augmented with external control circuitry to make them perform additional power-handling functions as needed for specific applications. Because identical SiC MCPM building blocks could be utilized in such a variety of ways, the cost and difficulty of designing new, highly reliable power systems would be reduced considerably. This concludes the information from the cited prior article. The main activity since the previously reported stage of development was the design, fabrication, and testing a 120- VDC-to-28-VDC modular power-converter system composed of eight SiC MCPMs in a 4 (parallel)-by-2 (series) matrix configuration, with normally-off controllable power switches. The SiC MCPM power modules include closed-loop control subsystems and are capable of operating at high power density or high temperature. The system was tested under various configurations, load conditions, load-transient conditions, and failure-recovery conditions. Planned future work includes refinement of the demonstrated modular system concept and development of a new converter hardware topology that would enable sharing of currents without the need for communication among modules. Toward these ends, it is also planned to develop a new converter control algorithm that would provide for improved sharing of current and power under all conditions, and to implement advanced packaging concepts that would enable operation at higher power density.

JPRS Report, Science & Technology Europe

DTIC Science & Technology

1992-08-12

Head on Chip Industry, Plans [Heinrich von Pierer Interview; Bonn DIE WELT, 15 Jun 92] 33 Swiss Contraves Develops High-Density Multichip Module... Investment costs are low because the method is based on low pressure, 0.1-1.0 MPA, during injection. This permits the use of simpler molds and...For example, ABS Pumpen AG [ABS Pumps German Stock Corporation] in Lohmar needed 1.5 years to define the "Ceramic Compo- nents for Friction

High Flux Heat Exchanger

DTIC Science & Technology

1993-01-01

maximum jet velocity (6.36 m/s), and maximum number of jets (nine). Wadsworth and Mudawar [49] describe the use of a single slotted nozzle to provide...H00503 (ASME), pp. 121-128, 1989. 40 49. D. C. Wadsworth and I. Mudawar , "Cooling of a Multichip Electronic Module by Means of Confined Two-Dimensional...Jets of Dielectric Liquid," HTD-Vol. 111, Heat Transfer in Electrglif, Book No. H00503 (ASME), pp. 79-87, 1989. 50. D.C. Wadsworth and I. Mudawar

Materials Processing and Manufacturing Technologies for Diamond Substrates Multichip Modules

DTIC Science & Technology

1994-10-14

document are those of the authors and should not be intepreted as representing the official policies, either express or implied, of the Defense Advanced...release of the diamond at the end of the deposition step, "* deposition of non-uniform films for stress/flatness control. 75kW Reactor & Modelling Studies...too strong (the film releases partially or not at all) to too weak (the film delaminates during the run from growth stresses), and are continuing to

Method for reworkable packaging of high speed, low electrical parasitic power electronics modules through gate drive integration

DOEpatents

Passmore, Brandon; Cole, Zach; Whitaker, Bret; Barkley, Adam; McNutt, Ty; Lostetter, Alexander

2016-08-02

A multichip power module directly connecting the busboard to a printed-circuit board that is attached to the power substrate enabling extremely low loop inductance for extreme environments such as high temperature operation. Wire bond interconnections are taught from the power die directly to the busboard further enabling enable low parasitic interconnections. Integration of on-board high frequency bus capacitors provide extremely low loop inductance. An extreme environment gate driver board allows close physical proximity of gate driver and power stage to reduce overall volume and reduce impedance in the control circuit. Parallel spring-loaded pin gate driver PCB connections allows a reliable and reworkable power module to gate driver interconnections.

An analog silicon retina with multichip configuration.

PubMed

Kameda, Seiji; Yagi, Tetsuya

2006-01-01

The neuromorphic silicon retina is a novel analog very large scale integrated circuit that emulates the structure and the function of the retinal neuronal circuit. We fabricated a neuromorphic silicon retina, in which sample/hold circuits were embedded to generate fluctuation-suppressed outputs in the previous study [1]. The applications of this silicon retina, however, are limited because of a low spatial resolution and computational variability. In this paper, we have fabricated a multichip silicon retina in which the functional network circuits are divided into two chips: the photoreceptor network chip (P chip) and the horizontal cell network chip (H chip). The output images of the P chip are transferred to the H chip with analog voltages through the line-parallel transfer bus. The sample/hold circuits embedded in the P and H chips compensate for the pattern noise generated on the circuits, including the analog communication pathway. Using the multichip silicon retina together with an off-chip differential amplifier, spatial filtering of the image with an odd- and an even-symmetric orientation selective receptive fields was carried out in real time. The analog data transfer method in the present multichip silicon retina is useful to design analog neuromorphic multichip systems that mimic the hierarchical structure of neuronal networks in the visual system.

High density electronic circuit and process for making

DOEpatents

Morgan, William P.

1999-01-01

High density circuits with posts that protrude beyond one surface of a substrate to provide easy mounting of devices such as integrated circuits. The posts also provide stress relief to accommodate differential thermal expansion. The process allows high interconnect density with fewer alignment restrictions and less wasted circuit area than previous processes. The resulting substrates can be test platforms for die testing and for multi-chip module substrate testing. The test platform can contain active components and emulate realistic operational conditions, replacing shorts/opens net testing.

Custom chipset and compact module design for a 75-110 GHz laboratory signal source

NASA Astrophysics Data System (ADS)

Morgan, Matthew A.; Boyd, Tod A.; Castro, Jason J.

2016-12-01

We report on the development and characterization of a compact, full-waveguide bandwidth (WR-10) signal source for general-purpose testing of mm-wave components. The monolithic microwave integrated circuit (MMIC) based multichip module is designed for compactness and ease-of-use, especially in size-constrained test sets such as a wafer probe station. It takes as input a cm-wave continuous-wave (CW) reference and provides a factor of three frequency multiplication as well as amplification, output power adjustment, and in situ output power monitoring. It utilizes a number of custom MMIC chips such as a Schottky-diode limiter and a broadband mm-wave detector, both designed explicitly for this module, as well as custom millimeter-wave multipliers and amplifiers reported in previous papers.

Silicon Heat Pipe Array

NASA Technical Reports Server (NTRS)

Yee, Karl Y.; Ganapathi, Gani B.; Sunada, Eric T.; Bae, Youngsam; Miller, Jennifer R.; Beinsford, Daniel F.

2013-01-01

Improved methods of heat dissipation are required for modern, high-power density electronic systems. As increased functionality is progressively compacted into decreasing volumes, this need will be exacerbated. High-performance chip power is predicted to increase monotonically and rapidly with time. Systems utilizing these chips are currently reliant upon decades of old cooling technology. Heat pipes offer a solution to this problem. Heat pipes are passive, self-contained, two-phase heat dissipation devices. Heat conducted into the device through a wick structure converts the working fluid into a vapor, which then releases the heat via condensation after being transported away from the heat source. Heat pipes have high thermal conductivities, are inexpensive, and have been utilized in previous space missions. However, the cylindrical geometry of commercial heat pipes is a poor fit to the planar geometries of microelectronic assemblies, the copper that commercial heat pipes are typically constructed of is a poor CTE (coefficient of thermal expansion) match to the semiconductor die utilized in these assemblies, and the functionality and reliability of heat pipes in general is strongly dependent on the orientation of the assembly with respect to the gravity vector. What is needed is a planar, semiconductor-based heat pipe array that can be used for cooling of generic MCM (multichip module) assemblies that can also function in all orientations. Such a structure would not only have applications in the cooling of space electronics, but would have commercial applications as well (e.g. cooling of microprocessors and high-power laser diodes). This technology is an improvement over existing heat pipe designs due to the finer porosity of the wick, which enhances capillary pumping pressure, resulting in greater effective thermal conductivity and performance in any orientation with respect to the gravity vector. In addition, it is constructed of silicon, and thus is better suited for the cooling of semiconductor devices.

Repairable chip bonding/interconnect process

DOEpatents

Bernhardt, Anthony F.; Contolini, Robert J.; Malba, Vincent; Riddle, Robert A.

1997-01-01

A repairable, chip-to-board interconnect process which addresses cost and testability issues in the multi-chip modules. This process can be carried out using a chip-on-sacrificial-substrate technique, involving laser processing. This process avoids the curing/solvent evolution problems encountered in prior approaches, as well is resolving prior plating problems and the requirements for fillets. For repairable high speed chip-to-board connection, transmission lines can be formed on the sides of the chip from chip bond pads, ending in a gull wing at the bottom of the chip for subsequent solder.

High density electronic circuit and process for making

DOEpatents

Morgan, W.P.

1999-06-29

High density circuits with posts that protrude beyond one surface of a substrate to provide easy mounting of devices such as integrated circuits are disclosed. The posts also provide stress relief to accommodate differential thermal expansion. The process allows high interconnect density with fewer alignment restrictions and less wasted circuit area than previous processes. The resulting substrates can be test platforms for die testing and for multi-chip module substrate testing. The test platform can contain active components and emulate realistic operational conditions, replacing shorts/opens net testing. 8 figs.

A modular microfluidic architecture for integrated biochemical analysis.

PubMed

Shaikh, Kashan A; Ryu, Kee Suk; Goluch, Edgar D; Nam, Jwa-Min; Liu, Juewen; Thaxton, C Shad; Chiesl, Thomas N; Barron, Annelise E; Lu, Yi; Mirkin, Chad A; Liu, Chang

2005-07-12

Microfluidic laboratory-on-a-chip (LOC) systems based on a modular architecture are presented. The architecture is conceptualized on two levels: a single-chip level and a multiple-chip module (MCM) system level. At the individual chip level, a multilayer approach segregates components belonging to two fundamental categories: passive fluidic components (channels and reaction chambers) and active electromechanical control structures (sensors and actuators). This distinction is explicitly made to simplify the development process and minimize cost. Components belonging to these two categories are built separately on different physical layers and can communicate fluidically via cross-layer interconnects. The chip that hosts the electromechanical control structures is called the microfluidic breadboard (FBB). A single LOC module is constructed by attaching a chip comprised of a custom arrangement of fluid routing channels and reactors (passive chip) to the FBB. Many different LOC functions can be achieved by using different passive chips on an FBB with a standard resource configuration. Multiple modules can be interconnected to form a larger LOC system (MCM level). We demonstrated the utility of this architecture by developing systems for two separate biochemical applications: one for detection of protein markers of cancer and another for detection of metal ions. In the first case, free prostate-specific antigen was detected at 500 aM concentration by using a nanoparticle-based bio-bar-code protocol on a parallel MCM system. In the second case, we used a DNAzyme-based biosensor to identify the presence of Pb(2+) (lead) at a sensitivity of 500 nM in <1 nl of solution.

Medical telesensors

NASA Astrophysics Data System (ADS)

Ferrell, Trinidad L.; Crilly, P. B.; Smith, S. F.; Wintenberg, Alan L.; Britton, Charles L., Jr.; Morrison, Gilbert W.; Ericson, M. N.; Hedden, D.; Bouldin, Donald W.; Passian, A.; Downey, Todd R.; Wig, A. G.; Meriaudeau, Fabrice

1998-05-01

Medical telesensors are self-contained integrated circuits for measuring and transmitting vital signs over a distance of approximately 1-2 meters. The circuits are unhoused and contain a sensor, signal processing and modulation electronics, a spread-spectrum transmitter, an antenna and a thin-film battery. We report on a body-temperature telesensor, which is sufficiently small to be placed on a tympanic membrane in a child's ear. We also report on a pulse-oximeter telesensor and a micropack receiver/long- range transmitter unit, which receives form a telesensor array and analyzes and re-transmits the vital signs over a longer range. Signal analytics are presented for the pulse oximeter, which is currently in the form of a finger ring. A multichip module is presented as the basic signal-analysis component. The module contains a microprocessor, a field=programmable gate array, memory elements and other components necessary for determining trauma and reporting signals.

Flexible manufacturing for photonics device assembly

NASA Technical Reports Server (NTRS)

Lu, Shin-Yee; Pocha, Michael D.; Strand, Oliver T.; Young, K. David

1994-01-01

The assembly of photonics devices such as laser diodes, optical modulators, and opto-electronics multi-chip modules (OEMCM), usually requires the placement of micron size devices such as laser diodes, and sub-micron precision attachment between optical fibers and diodes or waveguide modulators (usually referred to as pigtailing). This is a very labor intensive process. Studies done by the opto-electronics (OE) industry have shown that 95 percent of the cost of a pigtailed photonic device is due to the use of manual alignment and bonding techniques, which is the current practice in industry. At Lawrence Livermore National Laboratory, we are working to reduce the cost of packaging OE devices through the use of automation. Our efforts are concentrated on several areas that are directly related to an automated process. This paper will focus on our progress in two of those areas, in particular, an automated fiber pigtailing machine and silicon micro-technology compatible with an automated process.

Repairable chip bonding/interconnect process

DOEpatents

Bernhardt, A.F.; Contolini, R.J.; Malba, V.; Riddle, R.A.

1997-08-05

A repairable, chip-to-board interconnect process which addresses cost and testability issues in the multi-chip modules is disclosed. This process can be carried out using a chip-on-sacrificial-substrate technique, involving laser processing. This process avoids the curing/solvent evolution problems encountered in prior approaches, as well is resolving prior plating problems and the requirements for fillets. For repairable high speed chip-to-board connection, transmission lines can be formed on the sides of the chip from chip bond pads, ending in a gull wing at the bottom of the chip for subsequent solder. 10 figs.

Advanced flight computer. Special study

NASA Technical Reports Server (NTRS)

Coo, Dennis

1995-01-01

This report documents a special study to define a 32-bit radiation hardened, SEU tolerant flight computer architecture, and to investigate current or near-term technologies and development efforts that contribute to the Advanced Flight Computer (AFC) design and development. An AFC processing node architecture is defined. Each node may consist of a multi-chip processor as needed. The modular, building block approach uses VLSI technology and packaging methods that demonstrate a feasible AFC module in 1998 that meets that AFC goals. The defined architecture and approach demonstrate a clear low-risk, low-cost path to the 1998 production goal, with intermediate prototypes in 1996.

Interactions of the Human MCM-BP Protein with MCM Complex Components and Dbf4

PubMed Central

Nguyen, Tin; Jagannathan, Madhav; Shire, Kathy; Frappier, Lori

2012-01-01

MCM-BP was discovered as a protein that co-purified from human cells with MCM proteins 3 through 7; results which were recapitulated in frogs, yeast and plants. Evidence in all of these organisms supports an important role for MCM-BP in DNA replication, including contributions to MCM complex unloading. However the mechanisms by which MCM-BP functions and associates with MCM complexes are not well understood. Here we show that human MCM-BP is capable of interacting with individual MCM proteins 2 through 7 when co-expressed in insect cells and can greatly increase the recovery of some recombinant MCM proteins. Glycerol gradient sedimentation analysis indicated that MCM-BP interacts most strongly with MCM4 and MCM7. Similar gradient analyses of human cell lysates showed that only a small amount of MCM-BP overlapped with the migration of MCM complexes and that MCM complexes were disrupted by exogenous MCM-BP. In addition, large complexes containing MCM-BP and MCM proteins were detected at mid to late S phase, suggesting that the formation of specific MCM-BP complexes is cell cycle regulated. We also identified an interaction between MCM-BP and the Dbf4 regulatory component of the DDK kinase in both yeast 2-hybrid and insect cell co-expression assays, and this interaction was verified by co-immunoprecipitation of endogenous proteins from human cells. In vitro kinase assays showed that MCM-BP was not a substrate for DDK but could inhibit DDK phosphorylation of MCM4,6,7 within MCM4,6,7 or MCM2-7 complexes, with little effect on DDK phosphorylation of MCM2. Since DDK is known to activate DNA replication through phosphorylation of these MCM proteins, our results suggest that MCM-BP may affect DNA replication in part by regulating MCM phosphorylation by DDK. PMID:22540012

Interactions of the human MCM-BP protein with MCM complex components and Dbf4.

PubMed

Nguyen, Tin; Jagannathan, Madhav; Shire, Kathy; Frappier, Lori

2012-01-01

MCM-BP was discovered as a protein that co-purified from human cells with MCM proteins 3 through 7; results which were recapitulated in frogs, yeast and plants. Evidence in all of these organisms supports an important role for MCM-BP in DNA replication, including contributions to MCM complex unloading. However the mechanisms by which MCM-BP functions and associates with MCM complexes are not well understood. Here we show that human MCM-BP is capable of interacting with individual MCM proteins 2 through 7 when co-expressed in insect cells and can greatly increase the recovery of some recombinant MCM proteins. Glycerol gradient sedimentation analysis indicated that MCM-BP interacts most strongly with MCM4 and MCM7. Similar gradient analyses of human cell lysates showed that only a small amount of MCM-BP overlapped with the migration of MCM complexes and that MCM complexes were disrupted by exogenous MCM-BP. In addition, large complexes containing MCM-BP and MCM proteins were detected at mid to late S phase, suggesting that the formation of specific MCM-BP complexes is cell cycle regulated. We also identified an interaction between MCM-BP and the Dbf4 regulatory component of the DDK kinase in both yeast 2-hybrid and insect cell co-expression assays, and this interaction was verified by co-immunoprecipitation of endogenous proteins from human cells. In vitro kinase assays showed that MCM-BP was not a substrate for DDK but could inhibit DDK phosphorylation of MCM4,6,7 within MCM4,6,7 or MCM2-7 complexes, with little effect on DDK phosphorylation of MCM2. Since DDK is known to activate DNA replication through phosphorylation of these MCM proteins, our results suggest that MCM-BP may affect DNA replication in part by regulating MCM phosphorylation by DDK.

MCM-BP regulates unloading of the MCM2–7 helicase in late S phase

PubMed Central

Nishiyama, Atsuya; Frappier, Lori; Méchali, Marcel

2011-01-01

Origins of DNA replication are licensed by recruiting MCM2–7 to assemble the prereplicative complex (pre-RC). How MCM2–7 is inactivated or removed from chromatin at the end of S phase is still unclear. Here, we show that MCM-BP can disassemble the MCM2–7 complex and might function as an unloader of MCM2–7 from chromatin. In Xenopus egg extracts, MCM-BP exists in a stable complex with MCM7, but is not associated with the MCM2–7 hexameric complex. MCM-BP accumulates in nuclei in late S phase, well after the loading of MCM2–7 onto chromatin. MCM-BP immunodepletion in Xenopus egg extracts inhibits replication-dependent MCM dissociation without affecting pre-RC formation and DNA replication. When excess MCM-BP is incubated with Xenopus egg extracts or immunopurified MCM2–7, it binds to MCM proteins and promotes disassembly of the MCM2–7 complex. Recombinant MCM-BP also releases MCM2–7 from isolated late-S-phase chromatin, but this activity is abolished when DNA replication is blocked. MCM-BP silencing in human cells also delays MCM dissociation in late S phase. We propose that MCM-BP plays a key role in the mechanism by which pre-RC is cleared from replicated DNA in vertebrate cells. PMID:21196493

Recruitment of Mcm10 to Sites of Replication Initiation Requires Direct Binding to the Minichromosome Maintenance (MCM) Complex*

PubMed Central

Douglas, Max E.

2016-01-01

Mcm10 is required for the initiation of eukaryotic DNA replication and contributes in some unknown way to the activation of the Cdc45-MCM-GINS (CMG) helicase. How Mcm10 is localized to sites of replication initiation is unclear, as current models indicate that direct binding to minichromosome maintenance (MCM) plays a role, but the details and functional importance of this interaction have not been determined. Here, we show that purified Mcm10 can bind both DNA-bound double hexamers and soluble single hexamers of MCM. The binding of Mcm10 to MCM requires the Mcm10 C terminus. Moreover, the binding site for Mcm10 on MCM includes the Mcm2 and Mcm6 subunits and overlaps that for the loading factor Cdt1. Whether Mcm10 recruitment to replication origins depends on CMG helicase assembly has been unclear. We show that Mcm10 recruitment occurs via two modes: low affinity recruitment in the absence of CMG assembly (“G1-like”) and high affinity recruitment when CMG assembly takes place (“S-phase-like”). Mcm10 that cannot bind directly to MCM is defective in both modes of recruitment and is unable to support DNA replication. These findings indicate that Mcm10 is localized to replication initiation sites by directly binding MCM through the Mcm10 C terminus. PMID:26719337

Development of a chlorine chemistry module for the Master Chemical Mechanism

NASA Astrophysics Data System (ADS)

Xue, L. K.; Saunders, S. M.; Wang, T.; Gao, R.; Wang, X. F.; Zhang, Q. Z.; Wang, W. X.

2015-06-01

The chlorine atom (Cl·) has a high potential to perturb atmospheric photochemistry by oxidizing volatile organic compounds (VOCs), but the exact role it plays in the polluted troposphere remains unclear. The Master Chemical Mechanism (MCM) is a near explicit mechanism that has been widely applied in the atmospheric chemistry research. While it addresses comprehensively the chemistry initiated by the OH, O3 and NO3 radicals, its representation of the Cl· chemistry is incomplete as it only considers the reactions for alkanes. In this paper, we develop a more comprehensive Cl· chemistry module that can be directly incorporated within the MCM framework. A suite of 199 chemical reactions describes the Cl·-initiated degradation of alkenes, aromatics, aldehydes, ketones, alcohols, and some organic acids and nitrates, along with the inorganic chemistry involving Cl· and its precursors. To demonstrate the potential influence of the new chemistry module, it was incorporated into a MCM box model to evaluate the impacts of nitryl chloride (ClNO2), a product of nocturnal halogen activation by nitrogen oxides (NOx), on the following-day's atmospheric photochemistry. With constraints of recent observations collected at a coastal site in Hong Kong, southern China, the modeling analyses suggest that the Cl· produced from ClNO2 photolysis may substantially enhance the atmospheric oxidative capacity, VOC oxidation, and O3 formation, particularly in the early morning period. The results demonstrate the critical need for photochemical models to include more fully chlorine chemistry in order to better understand the atmospheric photochemistry in polluted environments subject to intense emissions of NOx, VOCs and chlorine-containing constituents.

Development of a chlorine chemistry module for the Master Chemical Mechanism

NASA Astrophysics Data System (ADS)

Xue, L. K.; Saunders, S. M.; Wang, T.; Gao, R.; Wang, X. F.; Zhang, Q. Z.; Wang, W. X.

2015-10-01

The chlorine atom (Cl·) has a high potential to perturb atmospheric photochemistry by oxidizing volatile organic compounds (VOCs), but the exact role it plays in the polluted troposphere remains unclear. The Master Chemical Mechanism (MCM) is a near-explicit mechanism that has been widely applied in the atmospheric chemistry research. While it addresses comprehensively the chemistry initiated by the OH, O3 and NO3 radicals, its representation of the Cl· chemistry is incomplete as it only considers the reactions for alkanes. In this paper, we develop a more comprehensive Cl· chemistry module that can be directly incorporated within the MCM framework. A suite of 205 chemical reactions describes the Cl·-initiated degradation of alkenes, aromatics, alkynes, aldehydes, ketones, alcohols, and some organic acids and nitrates, along with the inorganic chemistry involving Cl· and its precursors. To demonstrate the potential influence of the new chemistry module, it was incorporated into a MCM box model to evaluate the impacts of nitryl chloride (ClNO2), a product of nocturnal halogen activation by nitrogen oxides (NOX), on the following day's atmospheric photochemistry. With constraints of recent observations collected at a coastal site in Hong Kong, southern China, the modeling analyses suggest that the Cl· produced from ClNO2 photolysis may substantially enhance the atmospheric oxidative capacity, VOC oxidation and O3 formation, particularly in the early morning period. The results demonstrate the critical need for photochemical models to include more detailed chlorine chemistry in order to better understand the atmospheric photochemistry in polluted environments subject to intense emissions of NOX, VOCs and chlorine-containing constituents.

Recruitment of Mcm10 to Sites of Replication Initiation Requires Direct Binding to the Minichromosome Maintenance (MCM) Complex.

PubMed

Douglas, Max E; Diffley, John F X

2016-03-11

Mcm10 is required for the initiation of eukaryotic DNA replication and contributes in some unknown way to the activation of the Cdc45-MCM-GINS (CMG) helicase. How Mcm10 is localized to sites of replication initiation is unclear, as current models indicate that direct binding to minichromosome maintenance (MCM) plays a role, but the details and functional importance of this interaction have not been determined. Here, we show that purified Mcm10 can bind both DNA-bound double hexamers and soluble single hexamers of MCM. The binding of Mcm10 to MCM requires the Mcm10 C terminus. Moreover, the binding site for Mcm10 on MCM includes the Mcm2 and Mcm6 subunits and overlaps that for the loading factor Cdt1. Whether Mcm10 recruitment to replication origins depends on CMG helicase assembly has been unclear. We show that Mcm10 recruitment occurs via two modes: low affinity recruitment in the absence of CMG assembly ("G1-like") and high affinity recruitment when CMG assembly takes place ("S-phase-like"). Mcm10 that cannot bind directly to MCM is defective in both modes of recruitment and is unable to support DNA replication. These findings indicate that Mcm10 is localized to replication initiation sites by directly binding MCM through the Mcm10 C terminus. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Nuclear localization of Schizosaccharomyces pombe Mcm2/Cdc19p requires MCM complex assembly.

PubMed

Pasion, S G; Forsburg, S L

1999-12-01

The minichromosome maintenance (MCM) proteins MCM2-MCM7 are conserved eukaryotic replication factors that assemble in a heterohexameric complex. In fission yeast, these proteins are nuclear throughout the cell cycle. In studying the mechanism that regulates assembly of the MCM complex, we analyzed the cis and trans elements required for nuclear localization of a single subunit, Mcm2p. Mutation of any single mcm gene leads to redistribution of wild-type MCM subunits to the cytoplasm, and this redistribution depends on an active nuclear export system. We identified the nuclear localization signal sequences of Mcm2p and showed that these are required for nuclear targeting of other MCM subunits. In turn, Mcm2p must associate with other MCM proteins for its proper localization; nuclear localization of MCM proteins thus requires assembly of MCM proteins in a complex. We suggest that coupling complex assembly to nuclear targeting and retention ensures that only intact heterohexameric MCM complexes remain nuclear.

Nuclear Localization of Schizosaccharomyces pombe Mcm2/Cdc19p Requires MCM Complex Assembly

PubMed Central

Pasion, Sally G.; Forsburg, Susan L.

1999-01-01

The minichromosome maintenance (MCM) proteins MCM2–MCM7 are conserved eukaryotic replication factors that assemble in a heterohexameric complex. In fission yeast, these proteins are nuclear throughout the cell cycle. In studying the mechanism that regulates assembly of the MCM complex, we analyzed the cis and trans elements required for nuclear localization of a single subunit, Mcm2p. Mutation of any single mcm gene leads to redistribution of wild-type MCM subunits to the cytoplasm, and this redistribution depends on an active nuclear export system. We identified the nuclear localization signal sequences of Mcm2p and showed that these are required for nuclear targeting of other MCM subunits. In turn, Mcm2p must associate with other MCM proteins for its proper localization; nuclear localization of MCM proteins thus requires assembly of MCM proteins in a complex. We suggest that coupling complex assembly to nuclear targeting and retention ensures that only intact heterohexameric MCM complexes remain nuclear. PMID:10588642

A new MCM modification cycle regulates DNA replication initiation.

PubMed

Wei, Lei; Zhao, Xiaolan

2016-03-01

The MCM DNA helicase is a central regulatory target during genome replication. MCM is kept inactive during G1, and it initiates replication after being activated in S phase. During this transition, the only known chemical change to MCM is the gain of multisite phosphorylation that promotes cofactor recruitment. Because replication initiation is intimately linked to multiple biological cues, additional changes to MCM can provide further regulatory points. Here, we describe a yeast MCM SUMOylation cycle that regulates replication. MCM subunits undergo SUMOylation upon loading at origins in G1 before MCM phosphorylation. MCM SUMOylation levels then decline as MCM phosphorylation levels rise, thus suggesting an inhibitory role of MCM SUMOylation during replication. Indeed, increasing MCM SUMOylation impairs replication initiation, partly through promoting the recruitment of a phosphatase that decreases MCM phosphorylation and activation. We propose that MCM SUMOylation counterbalances kinase-based regulation, thus ensuring accurate control of replication initiation.

An Mcm10 Mutant Defective in ssDNA Binding Shows Defects in DNA Replication Initiation.

PubMed

Perez-Arnaiz, Patricia; Kaplan, Daniel L

2016-11-20

Mcm10 is an essential protein that functions to initiate DNA replication after the formation of the replication fork helicase. In this manuscript, we identified a budding yeast Mcm10 mutant (Mcm10-m2,3,4) that is defective in DNA binding in vitro. Moreover, this Mcm10-m2,3,4 mutant does not stimulate the phosphorylation of Mcm2 by Dbf4-dependent kinase (DDK) in vitro. When we expressed wild-type levels of mcm10-m2,3,4 in budding yeast cells, we observed a severe growth defect and a substantially decreased DNA replication. We also observed a substantially reduced replication protein A- chromatin immunoprecipitation signal at origins of replication, reduced levels of DDK-phosphorylated Mcm2, and diminished Go, Ichi, Ni, and San (GINS) association with Mcm2-7 in vivo. mcm5-bob1 bypasses the growth defect conferred by DDK-phosphodead Mcm2 in budding yeast. However, the growth defect observed by expressing mcm10-m2,3,4 is not bypassed by the mcm5-bob1 mutation. Furthermore, origin melting and GINS association with Mcm2-7 are substantially decreased for cells expressing mcm10-m2,3,4 in the mcm5-bob1 background. Thus, the origin melting and GINS-Mcm2-7 interaction defects we observed for mcm10-m2,3,4 are not explained by decreased Mcm2 phosphorylation by DDK, since the defects persist in an mcm5-bob1 background. These data suggest that DNA binding by Mcm10 is essential for the initiation of DNA replication. Copyright © 2016 Elsevier Ltd. All rights reserved.

The MCM-associated protein MCM-BP is important for human nuclear morphology.

PubMed

Jagannathan, Madhav; Sakwe, Amos M; Nguyen, Tin; Frappier, Lori

2012-01-01

Mini-chromosome maintenance complex-binding protein (MCM-BP) was discovered as a protein that is strongly associated with human MCM proteins, known to be crucial for DNA replication in providing DNA helicase activity. The Xenopus MCM-BP homologue appears to play a role in unloading MCM complexes from chromatin after DNA synthesis; however, the importance of MCM-BP and its functional contribution to human cells has been unclear. Here we show that depletion of MCM-BP by sustained expression of short hairpin RNA (shRNA) results in highly abnormal nuclear morphology and centrosome amplification. The abnormal nuclear morphology was not seen with depletion of other MCM proteins and was rescued with shRNA-resistant MCM-BP. MCM-BP depletion was also found to result in transient activation of the G2 checkpoint, slowed progression through G2 and increased replication protein A foci, indicative of replication stress. In addition, MCM-BP depletion led to increased cellular levels of MCM proteins throughout the cell cycle including soluble MCM pools. The results suggest that MCM-BP makes multiple contributions to human cells that are not limited to unloading of the MCM complex.

Open-ringed structure of the Cdt1-Mcm2-7 complex as a precursor of the MCM double hexamer.

PubMed

Zhai, Yuanliang; Cheng, Erchao; Wu, Hao; Li, Ningning; Yung, Philip Yuk Kwong; Gao, Ning; Tye, Bik-Kwoon

2017-03-01

The minichromosome maintenance complex (MCM) hexameric complex (Mcm2-7) forms the core of the eukaryotic replicative helicase. During G1 phase, two Cdt1-Mcm2-7 heptamers are loaded onto each replication origin by the origin-recognition complex (ORC) and Cdc6 to form an inactive MCM double hexamer (DH), but the detailed loading mechanism remains unclear. Here we examine the structures of the yeast MCM hexamer and Cdt1-MCM heptamer from Saccharomyces cerevisiae. Both complexes form left-handed coil structures with a 10-15-Å gap between Mcm5 and Mcm2, and a central channel that is occluded by the C-terminal domain winged-helix motif of Mcm5. Cdt1 wraps around the N-terminal regions of Mcm2, Mcm6 and Mcm4 to stabilize the whole complex. The intrinsic coiled structures of the precursors provide insights into the DH formation, and suggest a spring-action model for the MCM during the initial origin melting and the subsequent DNA unwinding.

A new MCM modification cycle regulates DNA replication initiation

PubMed Central

Wei, Lei; Zhao, Xiaolan

2016-01-01

The MCM DNA helicase is a central regulatory target during genome replication. MCM is kept inactive during G1 and activated in S phase to initiate replication. During this transition, the only known chemical change on MCM is the gain of multi-site phosphorylation that promotes cofactor recruitment. As replication initiation is intimately linked to multiple biological cues, additional changes on MCM can provide further regulatory points. Here, we describe a yeast MCM sumoylation cycle that negatively regulates replication. MCM subunits undergo sumoylation upon loading at origins in G1 prior to MCM phosphorylation. MCM sumoylation levels then decline as MCM phosphorylation levels rise, suggesting an inhibitory role in replication. Indeed, increasing MCM sumoylation impairs replication initiation through promoting the recruitment of a phosphatase that reduces MCM phosphorylation and activation. MCM sumoylation thus counterbalances kinase-based regulation to ensure accurate control of replication initiation. PMID:26854664

Broad Frequency LTCC Vertical Interconnect Transition for Multichip Modules and System on Package Applications

NASA Technical Reports Server (NTRS)

Decrossas, Emmanuel; Glover, Michael D.; Porter, Kaoru; Cannon, Tom; Mantooth, H. Alan; Hamilton, M. C.

2013-01-01

Various stripline structures and flip chip interconnect designs for high-speed digital communication systems implemented in low temperature co-fired ceramic (LTCC) substrates are studied in this paper. Specifically, two different transition designs from edge launch 2.4 millimeter connectors to stripline transmission lines embedded in LTCC are discussed. After characterizing the DuPont (sup trademark) 9K7 green tape, different designs are proposed to improve signal integrity for high-speed digital data. The full-wave simulations and experimental data validate the presented designs over a broad frequency band from Direct Current to 50 gigahertz and beyond.

Ancient diversification of eukaryotic MCM DNA replication proteins

PubMed Central

Liu, Yuan; Richards, Thomas A; Aves, Stephen J

2009-01-01

Background Yeast and animal cells require six mini-chromosome maintenance proteins (Mcm2-7) for pre-replication complex formation, DNA replication initiation and DNA synthesis. These six individual MCM proteins form distinct heterogeneous subunits within a hexamer which is believed to form the replicative helicase and which associates with the essential but non-homologous Mcm10 protein during DNA replication. In contrast Archaea generally only possess one MCM homologue which forms a homohexameric MCM helicase. In some eukaryotes Mcm8 and Mcm9 paralogues also appear to be involved in DNA replication although their exact roles are unclear. Results We used comparative genomics and phylogenetics to reconstruct the diversification of the eukaryotic Mcm2-9 gene family, demonstrating that Mcm2-9 were formed by seven gene duplication events before the last common ancestor of the eukaryotes. Mcm2-7 protein paralogues were present in all eukaryote genomes studied suggesting that no gene loss or functional replacements have been tolerated during the evolutionary diversification of eukaryotes. Mcm8 and 9 are widely distributed in eukaryotes and group together on the MCM phylogenetic tree to the exclusion of all other MCM paralogues suggesting co-ancestry. Mcm8 and Mcm9 are absent in some taxa, including Trichomonas and Giardia, and appear to have been secondarily lost in some fungi and some animals. The presence and absence of Mcm8 and 9 is concordant in all taxa sampled with the exception of Drosophila species. Mcm10 is present in most eukaryotes sampled but shows no concordant pattern of presence or absence with Mcm8 or 9. Conclusion A multifaceted and heterogeneous Mcm2-7 hexamer evolved during the early evolution of the eukaryote cell in parallel with numerous other acquisitions in cell complexity and prior to the diversification of extant eukaryotes. The conservation of all six paralogues throughout the eukaryotes suggests that each Mcm2-7 hexamer component has an exclusive functional role, either by a combination of unique lock and key interactions between MCM hexamer subunits and/or by a range of novel side interactions. Mcm8 and 9 evolved early in eukaryote cell evolution and their pattern of presence or absence suggests that they may have linked functions. Mcm8 is highly divergent in all Drosophila species and may not provide a good model for Mcm8 in other eukaryotes. PMID:19292915

Flip-chip replacement within the constraints imposed by multilayer ceramic (MLC) modules

NASA Astrophysics Data System (ADS)

Puttlitz, Karl J.

1984-01-01

Economics often dictates that suitable module rework procedures be established to replace solder bump devices (flip chips) reflowed to multichip carriers. These operations are complicated, owing to various constraints such as the substrate's physical and mechanical properties, close proximity of surface features, etc. This paper describes the constraints and the methods to circumvent them. An order of preference based upon the degree of constraint is recommended to achieve device removal and subsequent site dress of the residual solder left on the substrate. It has been determined that rework (device replacement) can be successfully achieved in even highly constricted situations. This is illustrated by the example of utilizing a localized heating technique, hot gas, to remove solder from microsockets from which chips were previously removed. Microsockets are areas to which chips are reflowed to the top surface of IBM's densely populated multilayer ceramic (MLC) modules, thus forming the so-called controlled collapse chip connection or C-4. The microsocket patterns are thus identical to the chip footprint.

Cdt1 stabilizes an open MCM ring for helicase loading.

PubMed

Frigola, Jordi; He, Jun; Kinkelin, Kerstin; Pye, Valerie E; Renault, Ludovic; Douglas, Max E; Remus, Dirk; Cherepanov, Peter; Costa, Alessandro; Diffley, John F X

2017-06-23

ORC, Cdc6 and Cdt1 act together to load hexameric MCM, the motor of the eukaryotic replicative helicase, into double hexamers at replication origins. Here we show that Cdt1 interacts with MCM subunits Mcm2, 4 and 6, which both destabilizes the Mcm2-5 interface and inhibits MCM ATPase activity. Using X-ray crystallography, we show that Cdt1 contains two winged-helix domains in the C-terminal half of the protein and a catalytically inactive dioxygenase-related N-terminal domain, which is important for MCM loading, but not for subsequent replication. We used these structures together with single-particle electron microscopy to generate three-dimensional models of MCM complexes. These show that Cdt1 stabilizes MCM in a left-handed spiral open at the Mcm2-5 gate. We propose that Cdt1 acts as a brace, holding MCM open for DNA entry and bound to ATP until ORC-Cdc6 triggers ATP hydrolysis by MCM, promoting both Cdt1 ejection and MCM ring closure.

Cdt1 stabilizes an open MCM ring for helicase loading

PubMed Central

Frigola, Jordi; He, Jun; Kinkelin, Kerstin; Pye, Valerie E.; Renault, Ludovic; Douglas, Max E.; Remus, Dirk; Cherepanov, Peter; Costa, Alessandro; Diffley, John F. X.

2017-01-01

ORC, Cdc6 and Cdt1 act together to load hexameric MCM, the motor of the eukaryotic replicative helicase, into double hexamers at replication origins. Here we show that Cdt1 interacts with MCM subunits Mcm2, 4 and 6, which both destabilizes the Mcm2–5 interface and inhibits MCM ATPase activity. Using X-ray crystallography, we show that Cdt1 contains two winged-helix domains in the C-terminal half of the protein and a catalytically inactive dioxygenase-related N-terminal domain, which is important for MCM loading, but not for subsequent replication. We used these structures together with single-particle electron microscopy to generate three-dimensional models of MCM complexes. These show that Cdt1 stabilizes MCM in a left-handed spiral open at the Mcm2–5 gate. We propose that Cdt1 acts as a brace, holding MCM open for DNA entry and bound to ATP until ORC–Cdc6 triggers ATP hydrolysis by MCM, promoting both Cdt1 ejection and MCM ring closure. PMID:28643783

SiC Multi-Chip Power Modules as Power-System Building Blocks

NASA Technical Reports Server (NTRS)

Lostetter, Alexander; Franks, Steven

2007-01-01

The term "SiC MCPMs" (wherein "MCPM" signifies "multi-chip power module") denotes electronic power-supply modules containing multiple silicon carbide power devices and silicon-on-insulator (SOI) control integrated-circuit chips. SiC MCPMs are being developed as building blocks of advanced expandable, reconfigurable, fault-tolerant power-supply systems. Exploiting the ability of SiC semiconductor devices to operate at temperatures, breakdown voltages, and current densities significantly greater than those of conventional Si devices, the designs of SiC MCPMs and of systems comprising multiple SiC MCPMs are expected to afford a greater degree of miniaturization through stacking of modules with reduced requirements for heat sinking. Moreover, the higher-temperature capabilities of SiC MCPMs could enable operation in environments hotter than Si-based power systems can withstand. The stacked SiC MCPMs in a given system can be electrically connected in series, parallel, or a series/parallel combination to increase the overall power-handling capability of the system. In addition to power connections, the modules have communication connections. The SOI controllers in the modules communicate with each other as nodes of a decentralized control network, in which no single controller exerts overall command of the system. Control functions effected via the network include synchronization of switching of power devices and rapid reconfiguration of power connections to enable the power system to continue to supply power to a load in the event of failure of one of the modules. In addition to serving as building blocks of reliable power-supply systems, SiC MCPMs could be augmented with external control circuitry to make them perform additional power-handling functions as needed for specific applications: typical functions could include regulating voltages, storing energy, and driving motors. Because identical SiC MCPM building blocks could be utilized in a variety of ways, the cost and difficulty of designing new, highly reliable power systems would be reduced considerably. Several prototype DC-to-DC power-converter modules containing SiC power-switching devices were designed and built to demonstrate the feasibility of the SiC MCPM concept. In anticipation of a future need for operation at high temperature, the circuitry in the modules includes high-temperature inductors and capacitors. These modules were designed to be stacked to construct a system of four modules electrically connected in series and/or parallel. The packaging of the modules is designed to satisfy requirements for series and parallel interconnection among modules, high power density, high thermal efficiency, small size, and light weight. Each module includes four output power connectors two for serial and two for parallel output power connections among the modules. Each module also includes two signal connectors, electrically isolated from the power connectors, that afford four zones for signal interconnections among the SOI controllers. Finally, each module includes two input power connectors, through which it receives power from an in-line power bus. This design feature is included in anticipation of a custom-designed power bus incorporating sockets compatible with snap-on type connectors to enable rapid replacement of failed modules.

Heterogeneous catalytic ozonation of clofibric acid using Ce/MCM-48: Preparation, reaction mechanism, comparison with Ce/MCM-41.

PubMed

Li, Shangyi; Tang, Yiming; Chen, Weirui; Hu, Zhe; Li, Xukai; Li, Laisheng

2017-10-15

Three-dimensional mesoporous MCM-48 and Ce loaded MCM-48 (Ce/MCM-48) were synthesized by hydrothermal and impregnating methods, respectively. They were characterized by XRD, SEM, TEM, EDS, XPS, N 2 adsorption-desorption techniques, and the results showed that Ce/MCM-48 still retained a highly ordered cubic structure. A series of experiments were conducted to study the catalytic activity of Ce/MCM-48 and Ce/MCM-41 for ozonation of clofibric acid in aqueous solution. Total Organic Carbon (TOC) removal efficiency in Ce/MCM-48/O 3 can be improved to 64% at 120min reaction time, 54% by Ce/MCM-41/O 3 , only 24% by MCM-48/O 3 , 23% by single ozonation. Ce/MCM-48 did not show any adsorption capacity for CA. Effect of initial pH revealed that active sites were surface protonated hydroxyl groups. The restraint of phosphate and sodium hydrogen sulfite (NaHSO 3 ) on the mineralization of CA illustrated more hydroxyl radicals were generated by Ce/MCM-48 catalysts than Ce/MCM-41. The degradation pathway of CA was investigated by the alterations of pH under different conditions. Recycle tests of catalysts demonstrated that compared with Ce/MCM-41, Ce/MCM-48 exhibited more excellent catalytic efficiency and stability because of its unique pore systems. Copyright © 2017 Elsevier Inc. All rights reserved.

MCM interference during licensing of DNA replication in Xenopus egg extracts-Possible Role of a C-terminal region of MCM3.

PubMed

Mimura, Satoru; Kubota, Yumiko; Takisawa, Haruhiko

2018-01-01

The minichromosome maintenance (MCM) complex, consisting of six subunits, Mcm2-7, is loaded onto replication origins through loading factors (origin recognition complex [ORC], Cdc6, and Cdt1) and forms an MCM double hexamer that licenses the initiation of DNA replication. Previous studies with Xenopus egg extracts showed that loading factors, especially Cdc6, dissociate from chromatin on MCM loading, but the molecular mechanism and physiological significance remain largely unknown. Using a cell-free system for MCM loading onto plasmid DNA in Xenopus egg extracts, we found that MCM loaded onto DNA prevents DNA binding of the loading factors ORC, Cdc6, and Cdt1. We further report that a peptide of the C-terminal region of MCM3 (MCM3-C), previously implicated in the initial association with ORC/Cdc6 in budding yeast, prevents ORC/Cdc6/Cdt1 binding to DNA in the absence of MCM loading. ATP-γ-S suppresses inhibitory activities of both the MCM loaded onto DNA and the MCM3-C peptide. Other soluble factors in the extract, but neither MCM nor Cdt1, are required for the activity. Conservation of the amino acid sequences of MCM3-C and its activity in vertebrates implies a novel negative autoregulatory mechanism that interferes with MCM loading in the vicinity of licensed origins to ensure proper origin licensing.

Synthesis of Nano-Zinc Oxide Loaded on Mesoporous Silica by Coordination Effect and Its Photocatalytic Degradation Property of Methyl Orange.

PubMed

Shen, Zhichuan; Zhou, Hongjun; Chen, Huayao; Xu, Hua; Feng, Chunhua; Zhou, Xinhua

2018-05-09

Salicylaldimine-modified mesoporous silica (Sal-MCM-3 and Sal-MCM-9) was prepared through a co-condensation method with different amounts of added salicylaldimine. With the coordination from the salicylaldimine, zinc ions were impregnated on Sal-MCM-3 and Sal-MCM-9. Then, Zn-Sal-MCM-3 and Zn-Sal-MCM-9 were calcined to obtain nano-zinc oxide loaded on mesoporous silica (ZnO-MCM-3 and ZnO-MCM-9). The material structures were systematically studied by Fourier transform infrared spectroscopy (FTIR), N₂ adsorption/desorption measurements, X-ray powder diffraction (XRD), zeta potential, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet diffused reflectance spectrum (UV-vis DRS), and thermogravimetry (TGA). Methyl orange (MO) was used to investigate the photocatalysis behavior of ZnO-MCM-3 and ZnO-MCM-9. The results confirmed that nano ZnO was loaded in the channels as well as the outside surface of mesoporous silica (MCM-41). The modification of salicylaldimine helped MCM-41 to load more nano ZnO on MCM-41. When the modification amount of salicylaldimine was one-ninth and one-third of the mass of the silicon source, respectively, the load of nano ZnO on ZnO-MCM-9 and ZnO-MCM-3 had atomic concentrations of 1.27 and 2.03, respectively. ZnO loaded on ZnO-MCM-9 had a wurtzite structure, while ZnO loaded on ZnO-MCM-3 was not in the same crystalline group. The blocking effect caused by nano ZnO in the channels reduced the orderliness of MCM-41. The photodegradation of MO can be divided in two processes, which are mainly controlled by the surface areas of ZnO-MCM and the loading amount of nano ZnO, respectively. The pseudo-first-order model was more suitable for the photodegradation process.

The investigation of MCM-48-type and MCM-41-type mesoporous silica as oral solid dispersion carriers for water insoluble cilostazol.

PubMed

Wang, Yanzhu; Sun, Lizhang; Jiang, Tongying; Zhang, Jinghai; Zhang, Chen; Sun, Changshan; Deng, Yihui; Sun, Jin; Wang, Siling

2014-06-01

To explore the suitable application of MCM-41 (Mobil Composition of Matter number forty-one)-type and MCM-48-type mesoporous silica in the oral water insoluble drug delivery system. Cilostazol (CLT) as a model drug was loaded into synthesized MCM-48 (Mobil Composition of Matter number forty-eight) and commercial MCM-41 by three common methods. The obtained MCM-41, MCM-48 and CLT-loaded samples were characterized by means of nitrogen adsorption, thermogravimetric analysis, ultraviolet-visible spectrophotometry, scanning electron microscopy, transmission electron microscopy, differential scanning calorimetry and powder X-ray diffractometer. It was found that solvent evaporation method was preferred according to the drug loading efficiency and the maximum percent cumulative drug dissolution. MCM-48 with 3D cubic pore structure and MCM-41 with 2D long tubular structure are nearly spherical particles in 300-500 nm. Nevertheless, the silica carriers with similar large specific surface areas and concentrating pore size distributions (978.66 m(2)/g, 3.8 nm for MCM-41 and 1108.04 m(2)/g, 3.6 nm for MCM-48) exhibited different adsorption behaviors for CLT. The maximum percent cumulative drug release of the two CLT/silica solid dispersion (CLT-MCM-48 and CLT-MCM-41) was 63.41% and 85.78% within 60 min, respectively; while in the subsequent 12 h release experiment, almost 100% cumulative drug release were both obtained. In the pharmacokinetics aspect, the maximum plasma concentrations of CLT-MCM-48 reached 3.63 mg/L by 0.92 h. The AUC0-∞ values of the CLT-MCM-41 and CLT-MCM-48 were 1.14-fold and 1.73-fold, respectively, compared with the commercial preparation. Our findings suggest that MCM-41-type and MCM-48-type mesoporous silica have great promise as solid dispersion carriers for sustained and immediate release separately.

Argus: a 16-pixel millimeter-wave spectrometer for the Green Bank Telescope

NASA Astrophysics Data System (ADS)

Sieth, Matthew; Devaraj, Kiruthika; Voll, Patricia; Church, Sarah; Gawande, Rohit; Cleary, Kieran; Readhead, Anthony C. S.; Kangaslahti, Pekka; Samoska, Lorene; Gaier, Todd; Goldsmith, Paul F.; Harris, Andrew I.; Gundersen, Joshua O.; Frayer, David; White, Steve; Egan, Dennis; Reeves, Rodrigo

2014-07-01

We report on the development of Argus, a 16-pixel spectrometer, which will enable fast astronomical imaging over the 85-116 GHz band. Each pixel includes a compact heterodyne receiver module, which integrates two InP MMIC low-noise amplifiers, a coupled-line bandpass filter and a sub-harmonic Schottky diode mixer. The receiver signals are routed to and from the multi-chip MMIC modules with multilayer high frequency printed circuit boards, which includes LO splitters and IF amplifiers. Microstrip lines on flexible circuitry are used to transport signals between temperature stages. The spectrometer frontend is designed to be scalable, so that the array design can be reconfigured for future instruments with hundreds of pixels. Argus is scheduled to be commissioned at the Robert C. Byrd Green Bank Telescope in late 2014. Preliminary data for the first Argus pixels are presented.

Minichromosome maintenance protein 2 and 3 promote osteosarcoma progression via DHX9 and predict poor patient prognosis

PubMed Central

Cheng, Dong-dong; Zhang, Hui-zhen; Yuan, Jun-qing; Li, Shi-jie; Yang, Qing-cheng; Fan, Cun-yi

2017-01-01

A label free quantitative proteomic approach (SWATH™ experiment) was performed to identify tumor-associated nuclear proteins that are differentially expressed between osteosarcoma cells and osteoblast cells. By functional screening, minichromosome maintenance protein 2 (MCM2) and minichromosome maintenance protein 3 (MCM3) were found to be related to osteosarcoma cell growth. Here, we show that knockdown of MCM2 or MCM3 inhibits osteosarcoma growth in vitro and in vivo. In co-immunoprecipitation and co-localization experiments, MCM2 and MCM3 were found to interact with DExH-box helicase 9 (DHX9) in osteosarcoma cells. A rescue study showed that the decreased growth of osteosarcoma cells by MCM2 or MCM3 knockdown was reversed by DHX9 overexpression, indicating that MCM2 and MCM3 activity was DHX9-dependent. In addition, the depletion of DHX9 hindered osteosarcoma cell proliferation. Notably, MCM2 and MCM3 expression levels were positively correlated with the DHX9 expression level in tumor samples and were associated with a poor prognosis in patients with osteosarcoma. Taken together, these results suggest that the MCM2/MCM3–DHX9 axis has an important role in osteosarcoma progression. PMID:28460433

Adsorption of CO2 on amine-functionalised MCM-41: experimental and theoretical studies.

PubMed

dos Santos, Thiago Custódio; Bourrelly, Sandrine; Llewellyn, Philip L; Carneiro, José Walkimar de M; Ronconi, Célia Machado

2015-04-28

Adsorption of CO2 on MCM-41 functionalised with [3-(2-aminoethylamino)propyl]trimethoxysilane (MCM-41-N2), N(1)-(3-trimethoxysilylpropyl)diethylenetriamine (MCM-41-N3), 4-aminopyridine (MCM-41-aminopyridine), 4-(methylamino)pyridine (MCM-41-methylaminopyridine) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (MCM-41-guanidine) was investigated. The amine-functionalised materials were characterised by (29)Si and (13)C solid-state nuclear magnetic resonance, N2 adsorption/desorption isotherms, X-ray diffraction and transmission electron microscopy. CO2 adsorption at 1.0 bar and 30 °C showed that the amount of CO2 (nads/mmol g(-1)) adsorbed on MCM-41-N2 and MCM-41-N3 is approximately twice the amount adsorbed on MCM-41. For MCM-41-aminopyridine, MCM-41-methylaminopyridine and MCM-41-guanidine, the CO2 adsorption capacity was smaller than that of MCM-41 at the same conditions. The proton affinity (computed with wB97x-D/6-311++G(d,p)) of the secondary amino groups is higher than that of the primary amino groups; however, the relative stabilities of the primary and secondary carbamates are similar. The differential heat of adsorption decreases as the number of secondary amino groups increases.

Mcm10 regulates DNA replication elongation by stimulating the CMG replicative helicase.

PubMed

Lõoke, Marko; Maloney, Michael F; Bell, Stephen P

2017-02-01

Activation of the Mcm2-7 replicative DNA helicase is the committed step in eukaryotic DNA replication initiation. Although Mcm2-7 activation requires binding of the helicase-activating proteins Cdc45 and GINS (forming the CMG complex), an additional protein, Mcm10, drives initial origin DNA unwinding by an unknown mechanism. We show that Mcm10 binds a conserved motif located between the oligonucleotide/oligosaccharide fold (OB-fold) and A subdomain of Mcm2. Although buried in the interface between these domains in Mcm2-7 structures, mutations predicted to separate the domains and expose this motif restore growth to conditional-lethal MCM10 mutant cells. We found that, in addition to stimulating initial DNA unwinding, Mcm10 stabilizes Cdc45 and GINS association with Mcm2-7 and stimulates replication elongation in vivo and in vitro. Furthermore, we identified a lethal allele of MCM10 that stimulates initial DNA unwinding but is defective in replication elongation and CMG binding. Our findings expand the roles of Mcm10 during DNA replication and suggest a new model for Mcm10 function as an activator of the CMG complex throughout DNA replication. © 2017 Lõoke et al.; Published by Cold Spring Harbor Laboratory Press.

Design and reliability analysis of high-speed and continuous data recording system based on disk array

NASA Astrophysics Data System (ADS)

Jiang, Changlong; Ma, Cheng; He, Ning; Zhang, Xugang; Wang, Chongyang; Jia, Huibo

2002-12-01

In many real-time fields the sustained high-speed data recording system is required. This paper proposes a high-speed and sustained data recording system based on the complex-RAID 3+0. The system consists of Array Controller Module (ACM), String Controller Module (SCM) and Main Controller Module (MCM). ACM implemented by an FPGA chip is used to split the high-speed incoming data stream into several lower-speed streams and generate one parity code stream synchronously. It also can inversely recover the original data stream while reading. SCMs record lower-speed streams from the ACM into the SCSI disk drivers. In the SCM, the dual-page buffer technology is adopted to implement speed-matching function and satisfy the need of sustainable recording. MCM monitors the whole system, controls ACM and SCMs to realize the data stripping, reconstruction, and recovery functions. The method of how to determine the system scale is presented. At the end, two new ways Floating Parity Group (FPG) and full 2D-Parity Group (full 2D-PG) are proposed to improve the system reliability and compared with the Traditional Parity Group (TPG). This recording system can be used conveniently in many areas of data recording, storing, playback and remote backup with its high-reliability.

Multiple domains of fission yeast Cdc19p (MCM2) are required for its association with the core MCM complex.

PubMed

Sherman, D A; Pasion, S G; Forsburg, S L

1998-07-01

The members of the MCM protein family are essential eukaryotic DNA replication factors that form a six-member protein complex. In this study, we use antibodies to four MCM proteins to investigate the structure of and requirements for the formation of fission yeast MCM complexes in vivo, with particular regard to Cdc19p (MCM2). Gel filtration analysis shows that the MCM protein complexes are unstable and can be broken down to subcomplexes. Using coimmunoprecipitation, we find that Mis5p (MCM6) and Cdc21p (MCM4) are tightly associated with one another in a core complex with which Cdc19p loosely associates. Assembly of Cdc19p with the core depends upon Cdc21p. Interestingly, there is no obvious change in Cdc19p-containing MCM complexes through the cell cycle. Using a panel of Cdc19p mutants, we find that multiple domains of Cdc19p are required for MCM binding. These studies indicate that MCM complexes in fission yeast have distinct substructures, which may be relevant for function.

Multiple Domains of Fission Yeast Cdc19p (MCM2) Are Required for Its Association with the Core MCM Complex

PubMed Central

Sherman, Daniel A.; Pasion, Sally G.; Forsburg, Susan L.

1998-01-01

The members of the MCM protein family are essential eukaryotic DNA replication factors that form a six-member protein complex. In this study, we use antibodies to four MCM proteins to investigate the structure of and requirements for the formation of fission yeast MCM complexes in vivo, with particular regard to Cdc19p (MCM2). Gel filtration analysis shows that the MCM protein complexes are unstable and can be broken down to subcomplexes. Using coimmunoprecipitation, we find that Mis5p (MCM6) and Cdc21p (MCM4) are tightly associated with one another in a core complex with which Cdc19p loosely associates. Assembly of Cdc19p with the core depends upon Cdc21p. Interestingly, there is no obvious change in Cdc19p-containing MCM complexes through the cell cycle. Using a panel of Cdc19p mutants, we find that multiple domains of Cdc19p are required for MCM binding. These studies indicate that MCM complexes in fission yeast have distinct substructures, which may be relevant for function. PMID:9658174

A Role for USP7 in DNA Replication

PubMed Central

Jagannathan, Madhav; Nguyen, Tin; Gallo, David; Luthra, Niharika; Brown, Grant W.; Saridakis, Vivian

2014-01-01

The minichromosome maintenance (MCM) complex, which plays multiple important roles in DNA replication, is loaded onto chromatin following mitosis, remains on chromatin until the completion of DNA synthesis, and then is unloaded by a poorly defined mechanism that involves the MCM binding protein (MCM-BP). Here we show that MCM-BP directly interacts with the ubiquitin-specific protease USP7, that this interaction occurs predominantly on chromatin, and that MCM-BP can tether USP7 to MCM proteins. Detailed biochemical and structure analyses of the USP7–MCM-BP interaction showed that the 155PSTS158 MCM-BP sequence mediates critical interactions with the TRAF domain binding pocket of USP7. Analysis of the effects of USP7 knockout on DNA replication revealed that lack of USP7 results in slowed progression through late S phase without globally affecting the fork rate or origin usage. Lack of USP7 also resulted in increased levels of MCM proteins on chromatin, and investigation of the cause of this increase revealed a defect in the dissociation of MCM proteins from chromatin in mid- to late S phase. This role of USP7 mirrors the previously described role for MCM-BP in MCM complex unloading and suggests that USP7 works with MCM-BP to unload MCM complexes from chromatin at the end of S phase. PMID:24190967

Archaeal MCM Proteins as an Analog for the Eukaryotic Mcm2–7 Helicase to Reveal Essential Features of Structure and Function

PubMed Central

Miller, Justin M.; Enemark, Eric J.

2015-01-01

In eukaryotes, the replicative helicase is the large multisubunit CMG complex consisting of the Mcm2–7 hexameric ring, Cdc45, and the tetrameric GINS complex. The Mcm2–7 ring assembles from six different, related proteins and forms the core of this complex. In archaea, a homologous MCM hexameric ring functions as the replicative helicase at the replication fork. Archaeal MCM proteins form thermostable homohexamers, facilitating their use as models of the eukaryotic Mcm2–7 helicase. Here we review archaeal MCM helicase structure and function and how the archaeal findings relate to the eukaryotic Mcm2–7 ring. PMID:26539061

Conserved mechanism for coordinating replication fork helicase assembly with phosphorylation of the helicase

PubMed Central

Bruck, Irina; Kaplan, Daniel L.

2015-01-01

Dbf4-dependent kinase (DDK) phosphorylates minichromosome maintenance 2 (Mcm2) during S phase in yeast, and Sld3 recruits cell division cycle 45 (Cdc45) to minichromosome maintenance 2-7 (Mcm2-7). We show here DDK-phosphoryled Mcm2 preferentially interacts with Cdc45 in vivo, and that Sld3 stimulates DDK phosphorylation of Mcm2 by 11-fold. We identified a mutation of the replication initiation factor Sld3, Sld3-m16, that is specifically defective in stimulating DDK phosphorylation of Mcm2. Wild-type expression levels of sld3-m16 result in severe growth and DNA replication defects. Cells expressing sld3-m16 exhibit no detectable Mcm2 phosphorylation in vivo, reduced replication protein A-ChIP signal at an origin, and diminished Go, Ichi, Ni, and San association with Mcm2-7. Treslin, the human homolog of Sld3, stimulates human DDK phosphorylation of human Mcm2 by 15-fold. DDK phosphorylation of human Mcm2 decreases the affinity of Mcm5 for Mcm2, suggesting a potential mechanism for helicase ring opening. These data suggest a conserved mechanism for replication initiation: Sld3/Treslin coordinates Cdc45 recruitment to Mcm2-7 with DDK phosphorylation of Mcm2 during S phase. PMID:26305950

Conserved mechanism for coordinating replication fork helicase assembly with phosphorylation of the helicase.

PubMed

Bruck, Irina; Kaplan, Daniel L

2015-09-08

Dbf4-dependent kinase (DDK) phosphorylates minichromosome maintenance 2 (Mcm2) during S phase in yeast, and Sld3 recruits cell division cycle 45 (Cdc45) to minichromosome maintenance 2-7 (Mcm2-7). We show here DDK-phosphoryled Mcm2 preferentially interacts with Cdc45 in vivo, and that Sld3 stimulates DDK phosphorylation of Mcm2 by 11-fold. We identified a mutation of the replication initiation factor Sld3, Sld3-m16, that is specifically defective in stimulating DDK phosphorylation of Mcm2. Wild-type expression levels of sld3-m16 result in severe growth and DNA replication defects. Cells expressing sld3-m16 exhibit no detectable Mcm2 phosphorylation in vivo, reduced replication protein A-ChIP signal at an origin, and diminished Go, Ichi, Ni, and San association with Mcm2-7. Treslin, the human homolog of Sld3, stimulates human DDK phosphorylation of human Mcm2 by 15-fold. DDK phosphorylation of human Mcm2 decreases the affinity of Mcm5 for Mcm2, suggesting a potential mechanism for helicase ring opening. These data suggest a conserved mechanism for replication initiation: Sld3/Treslin coordinates Cdc45 recruitment to Mcm2-7 with DDK phosphorylation of Mcm2 during S phase.

Metal-Chelate Immobilization of Lipase onto Polyethylenimine Coated MCM-41 for Apple Flavor Synthesis.

PubMed

Sadighi, Armin; Motevalizadeh, Seyed Farshad; Hosseini, Morteza; Ramazani, Ali; Gorgannezhad, Lena; Nadri, Hamid; Deiham, Behnaz; Ganjali, Mohammad Reza; Shafiee, Abbas; Faramarzi, Mohammad Ali; Khoobi, Mehdi

2017-08-01

An enzyme immobilized on a mesoporous silica nanoparticle can serve as a multiple catalyst for the synthesis of industrially useful chemicals. In this work, MCM-41 nanoparticles were coated with polyethylenimine (MCM-41@PEI) and further modified by chelation of divalent metal ions (M = Co 2+ , Cu 2+ , or Pd 2+ ) to produce metal-chelated silica nanoparticles (MCM-41@PEI-M). Thermomyces lanuginosa lipase (TLL) was immobilized onto MCM-41, MCM-41@PEI, and MCM-41@PEI-M by physical adsorption. Maximum immobilization yield and efficiency of 75 ± 3.5 and 65 ± 2.7% were obtained for MCM@PEI-Co, respectively. The highest biocatalytic activity at extremely acidic and basic pH (pH = 3 and 10) values were achieved for MCM-PEI-Co and MCM-PEI-Cu, respectively. Optimum enzymatic activity was observed for MCM-41@PEI-Co at 75 °C, while immobilized lipase on the Co-chelated support retained 70% of its initial activity after 14 days of storage at room temperature. Due to its efficient catalytic performance, MCM-41@PEI-Co was selected for the synthesis of ethyl valerate in the presence of valeric acid and ethanol. The enzymatic esterification yield for immobilized lipase onto MCM-41@PEI-Co was 60 and 53%, respectively, after 24 h of incubation in n-hexane and dimethyl sulfoxide media. Graphical Abstract Divalent metal chelated polyethylenimine coated MCM-41 (MCM-41@PEI-M) was used for immobilization of Thermomyces lanuginosa lipase catalyzing green apple flavor preparation.

Relationship between the structure of Fe-MCM-48 and its activity in catalytic ozonation for diclofenac mineralization.

PubMed

Li, Xukai; Chen, Weirui; Tang, Yiming; Li, Laisheng

2018-05-12

Fe-MCM-48 catalyst with a three-dimensional cubic pore structure was directly synthesized via a hydrothermal method, and the mineralization efficiency of diclofenac (DCF) in the catalytic ozonation process (Fe-MCM-48/O 3 ) was assessed. X-ray diffraction (XRD), N 2 adsorption desorption, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) characterizations revealed that Fe existed in the framework of MCM-48, and Fe-MCM-48 possessed a large surface area and a highly ordered cubic mesoporous structure, which could accelerate reactants and products diffusion. Regarding mineralization efficiency, the addition of Fe-MCM-48 significantly improved total organic carbon (TOC) removal, and approximately 49.9% TOC were removed through the Fe-MCM-48/O 3 process at 60 min, which was 2.0 times higher than that in single ozonation. Due to this catalyst's superior structure, Fe-MCM-48 showed the better catalytic activity compared with Fe-MCM-41 and Fe loaded MCM-48 (Fe/MCM-48, Fe existed on the surface of MCM-48). DCF removal in the Fe-MCM-48/O 3 process was primarily based on ozone direct oxidation. The improvement of mineralization efficiency was attributed to the function of generated hydroxyl radicals (•OH), which indicated that the presence of Fe-MCM-48 accelerated ozone decomposition. Moreover, the negatively charged surface of Fe-MCM-48 and the proper pH value of the DCF solution played an essential role in OH generation. Copyright © 2018 Elsevier Ltd. All rights reserved.

Highly reusability surface loaded metal particles magnetic catalyst microspheres (MCM-MPs) for treatment of dye-contaminated water

NASA Astrophysics Data System (ADS)

Liu, Ying; Zhang, Kun; Yin, Xiaoshuang; Yang, Wenzhong; Zhu, Hongjun

2016-04-01

The metal-deposited magnetic catalyst microspheres (MCM-MPs) were successfully synthesized by one facile, high yield and controllable approach. Here, the bare magnetic microspheres were firstly synthesized according to the solvothermal method. Then silica shell were coated on the surface of the magnetic microspheres via sol-gel method, and subsequently with surface modifying with amino in the purpose to form SiO2-NH2 shell. Thus, metal particles were easily adsorbed into the SiO2-NH2 shell and in-situ reduced by NaBH4 solution. All the obtained products (MCM-Cu, MCM-Ag, MCM-Pd) which were monodisperse and constitutionally stable were exhibited high magnetization and excellent catalytic activity towards dyes solution reduction. The catalytic rate ratio of MCM-Pd: MCM-Cu: MCM-Ag could be 10:3:1. Besides, some special coordination compound Cu2(OH)3Br had been generated in the in-situ reduced process of MCM-Cu, which produced superior cyclical stability (>20 times) than that of MCM-Ag and MCM-Pd. In all, those highly reusability and great catalytic efficiency of MCM-MPs show promising and great potential for treatment of dye-contaminated water.

Comparative Study of the Minichromosome Maintenance Proteins Complex (MCM 4/5/6) in Ameloblastoma and Unicystic Ameloblastoma.

PubMed

Apellániz, Delmira; Pereira-Prado, Vanesa; Sicco, Estefania; Vigil-Bastitta, Gabriela; González-González, Rogelio; Mosqueda-Taylor, Adalberto; Molina-Frechero, Nelly; Hernandez, Marcela; Sánchez-Romero, Celeste; Bologna-Molina, Ronell

2018-05-01

Solid/conventional ameloblastoma (AM) and unicystic ameloblastoma (UAM) are the most frequent benign epithelial odontogenic tumors located in the maxillary region, and their treatment usually consists of extensive surgical resection. Therefore, it is relevant to study molecular markers to better understand the biological behavior of these tumors. The aim of this study was to describe and compare the expression of proteins related to cellular proliferation: Ki-67 and MCM4-6 complex. An immunohistochemistry technique was performed, with antibodies against Ki-67, MCM4, MCM5, and MCM6, in 10 AM and 10 UAM tumors. The results were quantified using label index and analyzed statistically. AM and UAM had greater expression of MCM6, followed by MCM5, MCM4, and Ki-67 ( P < .05). Immunoexpression of Ki-67 and MCM5 was exclusively nuclear, whereas the expression of MCM4 and MCM6 was nuclear and cytoplasmic. The results suggest that MCM5 is a trustable cell proliferation marker with higher sensitivity compared with Ki-67 and may be useful to predict the biological behavior of AM and UAM. Despite this, further studies are necessary, including a correlation with clinical parameters to confirm these findings.

Gel-like properties of MCM-41 material and its transformation to MCM-50 in a caustic alkaline surround

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saputra, Hens; Othman, Raihan, E-mail: raihan@iium.edu.my; Sutjipto, A.G.E.

2012-03-15

Highlights: Black-Right-Pointing-Pointer MCM-41 material transforms gradually into MCM-50 lamellar gel upon controlled exposure to 6 M KOH. Black-Right-Pointing-Pointer The formation of MCM-50 ordered gel structure occurs at KOH weight content of 40-70 wt. %. Black-Right-Pointing-Pointer MCM gel phase shows pseudoplastic behavior and possesses homogeneous matrix texture. -- Abstract: MCM-41 material, prepared by sol-gel method, reveals gel-like properties in a caustic alkaline environment, i.e., 6 M potassium hydroxide (KOH) electrolyte. The gellation of MCM-41 starts at a KOH weight ratio of 40 wt.%. The structural change of the material is verified with X-Ray diffractograms and supported by observation using Scanning Electronmore » Microscope (SEM). As the KOH weight ratio increases, the MCM-41 hexagonal arrays structure gradually transforms into MCM-50 lamellar structure before disappearing completely at 80 wt.% KOH. The MCM gel phase is further characterized by rotational viscometry and texture analysis. The gel phase shows shear thinning or pseudoplastic behavior and possesses homogeneous matrix structure.« less

Highly stable loading of Mcm proteins onto chromatin in living cells requires replication to unload

PubMed Central

Kuipers, Marjorie A.; Stasevich, Timothy J.; Sasaki, Takayo; Wilson, Korey A.; Hazelwood, Kristin L.; McNally, James G.; Davidson, Michael W.

2011-01-01

The heterohexameric minichromosome maintenance protein complex (Mcm2-7) functions as the eukaryotic helicase during DNA replication. Mcm2-7 loads onto chromatin during early G1 phase but is not converted into an active helicase until much later during S phase. Hence, inactive Mcm complexes are presumed to remain stably bound from early G1 through the completion of S phase. Here, we investigated Mcm protein dynamics in live mammalian cells. We demonstrate that Mcm proteins are irreversibly loaded onto chromatin cumulatively throughout G1 phase, showing no detectable exchange with a gradually diminishing soluble pool. Eviction of Mcm requires replication; during replication arrest, Mcm proteins remained bound indefinitely. Moreover, the density of immobile Mcms is reduced together with chromatin decondensation within sites of active replication, which provides an explanation for the lack of colocalization of Mcm with replication fork proteins. These results provide in vivo evidence for an exceptionally stable lockdown mechanism to retain all loaded Mcm proteins on chromatin throughout prolonged cell cycles. PMID:21220507

Orientation-selective aVLSI spiking neurons.

PubMed

Liu, S C; Kramer, J; Indiveri, G; Delbrück, T; Burg, T; Douglas, R

2001-01-01

We describe a programmable multi-chip VLSI neuronal system that can be used for exploring spike-based information processing models. The system consists of a silicon retina, a PIC microcontroller, and a transceiver chip whose integrate-and-fire neurons are connected in a soft winner-take-all architecture. The circuit on this multi-neuron chip approximates a cortical microcircuit. The neurons can be configured for different computational properties by the virtual connections of a selected set of pixels on the silicon retina. The virtual wiring between the different chips is effected by an event-driven communication protocol that uses asynchronous digital pulses, similar to spikes in a neuronal system. We used the multi-chip spike-based system to synthesize orientation-tuned neurons using both a feedforward model and a feedback model. The performance of our analog hardware spiking model matched the experimental observations and digital simulations of continuous-valued neurons. The multi-chip VLSI system has advantages over computer neuronal models in that it is real-time, and the computational time does not scale with the size of the neuronal network.

Structural changes in Mcm5 protein bypass Cdc7-Dbf4 function and reduce replication origin efficiency in Saccharomyces cerevisiae.

PubMed

Hoang, Margaret L; Leon, Ronald P; Pessoa-Brandao, Luis; Hunt, Sonia; Raghuraman, M K; Fangman, Walton L; Brewer, Bonita J; Sclafani, Robert A

2007-11-01

Eukaryotic chromosomal replication is a complicated process with many origins firing at different efficiencies and times during S phase. Prereplication complexes are assembled on all origins in G(1) phase, and yet only a subset of complexes is activated during S phase by DDK (for Dbf4-dependent kinase) (Cdc7-Dbf4). The yeast mcm5-bob1 (P83L) mutation bypasses DDK but results in reduced intrinsic firing efficiency at 11 endogenous origins and at origins located on minichromosomes. Origin efficiency may result from Mcm5 protein assuming an altered conformation, as predicted from the atomic structure of an archaeal MCM (for minichromosome maintenance) homologue. Similarly, an intragenic mutation in a residue predicted to interact with P83L suppresses the mcm5-bob1 bypass phenotype. We propose DDK phosphorylation of the MCM complex normally results in a single, highly active conformation of Mcm5, whereas the mcm5-bob1 mutation produces a number of conformations, only one of which is permissive for origin activation. Random adoption of these alternate states by the mcm5-bob1 protein can explain both how origin firing occurs independently of DDK and why origin efficiency is reduced. Because similar mutations in mcm2 and mcm4 cannot bypass DDK, Mcm5 protein may be a unique Mcm protein that is the final target of DDK regulation.

Autonomous sensor-based dual-arm satellite grappling

NASA Technical Reports Server (NTRS)

Wilcox, Brian; Tso, Kam; Litwin, Todd; Hayati, Samad; Bon, Bruce

1989-01-01

Dual-arm satellite grappling involves the integration of technologies developed in the Sensing and Perception (S&P) Subsystem for object acquisition and tracking, and the Manipulator Control and Mechanization (MCM) Subsystem for dual-arm control. S&P acquires and tracks the position, orientation, velocity, and angular velocity of a slowly spinning satellite, and sends tracking data to the MCM subsystem. MCM grapples the satellite and brings it to rest, controlling the arms so that no excessive forces or torques are exerted on the satellite or arms. A 350-pound satellite mockup which can spin freely on a gimbal for several minutes, closely simulating the dynamics of a real satellite is demonstrated. The satellite mockup is fitted with a panel under which may be mounted various elements such as line replacement modules and electrical connectors that will be used to demonstrate servicing tasks once the satellite is docked. The subsystems are housed in three MicroVAX II microcomputers. The hardware of the S&P Subsystem includes CCD cameras, video digitizers, frame buffers, IMFEX (a custom pipelined video processor), a time-code generator with millisecond precision, and a MicroVAX II computer. Its software is written in Pascal and is based on a locally written vision software library. The hardware of the MCM Subsystem includes PUMA 560 robot arms, Lord force/torque sensors, two MicroVAX II computers, and unimation pneumatic parallel grippers. Its software is written in C, and is based on a robot language called RCCL. The two subsystems are described and test results on the grappling of the satellite mockup with rotational rates of up to 2 rpm are provided.

Towards co-packaging of photonics and microelectronics in existing manufacturing facilities

NASA Astrophysics Data System (ADS)

Janta-Polczynski, Alexander; Cyr, Elaine; Bougie, Jerome; Drouin, Alain; Langlois, Richard; Childers, Darrell; Takenobu, Shotaro; Taira, Yoichi; Lichoulas, Ted W.; Kamlapurkar, Swetha; Engelmann, Sebastian; Fortier, Paul; Boyer, Nicolas; Barwicz, Tymon

2018-02-01

The impact of integrated photonics on optical interconnects is currently muted by challenges in photonic packaging and in the dense integration of photonic modules with microelectronic components on printed circuit boards. Single mode optics requires tight alignment tolerance for optical coupling and maintaining this alignment in a cost-efficient package can be challenging during thermal excursions arising from downstream microelectronic assembly processes. In addition, the form factor of typical fiber connectors is incompatible with the dense module integration expected on printed circuit boards. We have implemented novel approaches to interfacing photonic chips to standard optical fibers. These leverage standard high throughput microelectronic assembly tooling and self-alignment techniques resulting in photonic packaging that is scalable in manufacturing volume and in the number of optical IOs per chip. In addition, using dense optical fiber connectors with space-efficient latching of fiber patch cables results in compact module size and efficient board integration, bringing the optics closer to the logic chip to alleviate bandwidth bottlenecks. This packaging direction is also well suited for embedding optics in multi-chip modules, including both photonic and microelectronic chips. We discuss the challenges and rewards in this type of configuration such as thermal management and signal integrity.

A study on hydrogen-storage behaviors of nickel-loaded mesoporous MCM-41.

PubMed

Park, Soo-Jin; Lee, Seul-Yi

2010-06-01

The objective of the present work was to investigate the possibility of improving the hydrogen-storage capacity of mesoporous MCM-41 containing nickel (Ni) oxides (Ni/MCM-41). The MCM-41 and Ni/MCM-41 were prepared using a hydrothermal process as a function of Ni content (2, 5, and 10 wt.% in the MCM-41). The surface functional groups of the Ni/MCM-41 were identified by Fourier transform infrared spectroscopy (FTIR). The structure and morphology of the Ni/MCM-41 were characterized by X-ray diffraction (XRD) and field emission transmission electron microscopy (FE-TEM). XRD results showed a well-ordered hexagonal pore structure; FE-TEM also revealed, as a complementary technique, the structure and pore size. The textural properties of the Ni/MCM-41 were analyzed using N(2) adsorption isotherms at 77 K. The hydrogen-storage capacity of the Ni/MCM-41 was evaluated at 298 K/100 bar. It was found that the presence of Ni on mesoporous MCM-41 created hydrogen-favorable sites that enhanced the hydrogen-storage capacity by a spillover effect. Furthermore, it was concluded that the hydrogen-storage capacity was greatly influenced by the amount of nickel oxide, resulting in a chemical reaction between Ni/MCM-41 and hydrogen molecules. Crown Copyright © 2010. Published by Elsevier Inc. All rights reserved.

Cdt1p, through its interaction with Mcm6p, is required for the formation, nuclear accumulation and chromatin loading of the MCM complex.

PubMed

Wu, Rentian; Wang, Jiafeng; Liang, Chun

2012-01-01

Regulation of DNA replication initiation is essential for the faithful inheritance of genetic information. Replication initiation is a multi-step process involving many factors including ORC, Cdt1p, Mcm2-7p and other proteins that bind to replication origins to form a pre-replicative complex (pre-RC). As a prerequisite for pre-RC assembly, Cdt1p and the Mcm2-7p heterohexameric complex accumulate in the nucleus in G1 phase in an interdependent manner in budding yeast. However, the nature of this interdependence is not clear, nor is it known whether Cdt1p is required for the assembly of the MCM complex. In this study, we provide the first evidence that Cdt1p, through its interaction with Mcm6p with the C-terminal regions of the two proteins, is crucial for the formation of the MCM complex in both the cytoplasm and nucleoplasm. We demonstrate that disruption of the interaction between Cdt1p and Mcm6p prevents the formation of the MCM complex, excludes Mcm2-7p from the nucleus, and inhibits pre-RC assembly and DNA replication. Our findings suggest a function for Cdt1p in promoting the assembly of the MCM complex and maintaining its integrity by interacting with Mcm6p.

Antibacterial nanocomposites based on chitosan/Co-MCM as a selective and efficient adsorbent for organic dyes.

PubMed

Khan, Shahid Ali; Khan, Sher Bahadar; Kamal, Tahseen; Yasir, Muhammad; Asiri, Abdullah M

2016-10-01

Chitosan/cobalt-silica (Co-MCM) nanocomposites were synthesized for the purification of effluent by adding 5, 15 and 25mL of Co-MCM solution to the aqueous chitosan solution for the formation of chitosan/Co-MCM-5, chitosan/Co-MCM-15 and chitosan/Co-MCM-25, respectively. These different nanocomposites were characterized by FESEM, EDS, X-ray crystallography and IR spectrophotometer and employed for the adsorption of various dyes (methyl orange, acridine orange, indigo carmine and congo red). The respective nanocomposites showed good adsorption toward methyl orange, indigo carmine and congo red while all nanocomposites were inactive for acridine orange dye. Among the nanocomposites, chitosan/Co-MCM-15 showed the highest adsorption performance which might be due to ideal dispersion of Co-MCM inside the chitosan polymer host. Chitosan/Co-MCM-15 exhibited high adsorption for methyl orange as compared to indigo carmine. We have further checked the biological potential of chitosan/Co-MCM nanocomposites against gram positive and negative bacteria as well as multi drug resistant bacteria. The results favor the strongest bioactivities of chitosan/Co-MCM-15 against various gram positive and gram negative bacteria as well as multi drug resistant bacteria, which further suggest the ideal dispersion of Co-MCM in chitosan polymer host and is responsible for the improvement of both adsorption as well as biological performance. Copyright © 2016 Elsevier B.V. All rights reserved.

A conserved MCM single-stranded DNA binding element is essential for replication initiation.

PubMed

Froelich, Clifford A; Kang, Sukhyun; Epling, Leslie B; Bell, Stephen P; Enemark, Eric J

2014-04-01

The ring-shaped MCM helicase is essential to all phases of DNA replication. The complex loads at replication origins as an inactive double-hexamer encircling duplex DNA. Helicase activation converts this species to two active single hexamers that encircle single-stranded DNA (ssDNA). The molecular details of MCM DNA interactions during these events are unknown. We determined the crystal structure of the Pyrococcus furiosus MCM N-terminal domain hexamer bound to ssDNA and define a conserved MCM-ssDNA binding motif (MSSB). Intriguingly, ssDNA binds the MCM ring interior perpendicular to the central channel with defined polarity. In eukaryotes, the MSSB is conserved in several Mcm2-7 subunits, and MSSB mutant combinations in S. cerevisiae Mcm2-7 are not viable. Mutant Mcm2-7 complexes assemble and are recruited to replication origins, but are defective in helicase loading and activation. Our findings identify an important MCM-ssDNA interaction and suggest it functions during helicase activation to select the strand for translocation. DOI: http://dx.doi.org/10.7554/eLife.01993.001.

A conserved MCM single-stranded DNA binding element is essential for replication initiation

PubMed Central

Froelich, Clifford A; Kang, Sukhyun; Epling, Leslie B; Bell, Stephen P; Enemark, Eric J

2014-01-01

The ring-shaped MCM helicase is essential to all phases of DNA replication. The complex loads at replication origins as an inactive double-hexamer encircling duplex DNA. Helicase activation converts this species to two active single hexamers that encircle single-stranded DNA (ssDNA). The molecular details of MCM DNA interactions during these events are unknown. We determined the crystal structure of the Pyrococcus furiosus MCM N-terminal domain hexamer bound to ssDNA and define a conserved MCM-ssDNA binding motif (MSSB). Intriguingly, ssDNA binds the MCM ring interior perpendicular to the central channel with defined polarity. In eukaryotes, the MSSB is conserved in several Mcm2-7 subunits, and MSSB mutant combinations in S. cerevisiae Mcm2-7 are not viable. Mutant Mcm2-7 complexes assemble and are recruited to replication origins, but are defective in helicase loading and activation. Our findings identify an important MCM-ssDNA interaction and suggest it functions during helicase activation to select the strand for translocation. DOI: http://dx.doi.org/10.7554/eLife.01993.001 PMID:24692448

Preparation, characterization and catalytic properties of MCM-48 supported tungstophosphoric acid mesoporous materials for green synthesis of benzoic acid

NASA Astrophysics Data System (ADS)

Wu, Hai-Yan; Zhang, Xiao-Li; Chen, Xi; Chen, Ya; Zheng, Xiu-Cheng

2014-03-01

MCM-48 and tungstophosphoric acid (HPW) were prepared and applied for the synthesis of HPW/MCM-48 mesoporous materials. The characterization results showed that HPW/MCM-48 obtained retained the typical mesopore structure of MCM-48, and the textural parameters decreased with the increase loading of HPW. The catalytic oxidation results of benzyl alcohol and benzaldehyde with 30% H2O2 indicated that HPW/MCM-48 was an efficient catalyst for the green synthesis of benzoic acid. Furthermore, 35 wt% HPW/MCM-48 sample showed the highest activity under the reaction conditions.

Fabrication of MCM-41 fibers with well-ordered hexagonal mesostructure controlled in acidic and alkaline media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jafarzadeh, A.; Sohrabnezhad, Sh., E-mail: sohrabnezhad@guilan.ac.ir; Zanjanchi, M.A.

In this paper, synthesis and characterization of two type morphologies of the MCM-41mesoporous material, nano and microfibers, were investigated by electrospinning technique. The synthesis was performed in acidic and alkaline media, separately. The MCM-41 morphologies were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray powder diffraction (XRD), and nitrogen adsorption–desorption measurement. Tetraethylorthosilicate (TEOS) and cetyltrimethylammonium bromide (CTAB) were used as silica and template sources for the synthesis of MCM-41 morphologies, respectively. The SEM results showed that MCM-41 nanofibers were spun in acidic media and microfibers of MCM-41 were produced in alkaline media. The XRD study revealed amore » long range structural ordering of mesoporous materials. The TEM results indicated rough surfaces with uniform average diameter 200 nm for nanofibers and 2 µm for microfibers. The pore diameter and surface area of calcined MCM-41 nanofibers were 2.2 nm and 970 m{sup 2}/g, respectively. For the MCM-41 microfibers, pore sizes of 2.7 nm and surface areas 420 m{sup 2}/g was measured. - Graphical abstract: Electrospinning method was used for fabricating of MCM-41 microfibers from TEOS in alkaline media (top) and MCM-41 nanofibers in acidic media (bottom). - Highlights: • Synthesis of MCM-41 nanofibers and microfibers by electrospinning technique. • MCM-41 nanofibers were synthesized in acidic media. • MCM-41 manofibers spun in alkaline media. • Electrospinning was a simple method for preparing of fibers with respect to chemical method.« less

The viability of MCM-41 as separator in secondary alkaline cells

NASA Astrophysics Data System (ADS)

Meskon, S. R.; Othman, R.; Ani, M. H.

2018-01-01

The viability of MCM-41 membrane as a separator material in secondary alkaline cell is investigated. The inorganic membrane was employed in an alkaline nickel-zinc system. MCM-41 mesoporous material consists of arrays of hexagonal nano-pore channels. The membrane was synthesized using sol-gel route from parent solution comprising of quarternary ammonium surfactant, cethyltrimethylammonium bromide C16H33(CH3)3NBr (CTAB), hydrochloric acid (HCl), deionized water (H2O), ethanol (C2H5OH), and tetraethylortosilicate (TEOS). Both the anodic zinc/zinc oxide and cathodic nickel hydroxide electrodeposited film were coated with MCM-41 membrane. The Ni/MCM-41/Zn alkaline cell was then subjected to 100-cycle durability test and the structural stability of MCM-41 separator throughout the progression of the charge-discharge cycles is studied. X-ray diffraction (XRD) analysis on the dismantled cell shows that MCM-41 began to transform to lamellar MCM-50 on the 5th cycle and transformed almost completely on the 25th cycle. The phase transformation of MCM-41 hexagonal structure into gel-like MCM-50 prevents the mesoporous cell separator from diminished in the caustic alkaline surround. This work has hence demonstrated MCM-41 membrane is viable to be employed in secondary alkaline cells.

MCM-41 support for ultrasmall γ-Fe 2O 3 nanoparticles for H 2S removal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cara, C.; Rombi, E.; Musinu, A.

In this paper, MCM-41 is proposed to build mesostructured Fe 2O 3-based sorbents as an alternative to other silica or alumina supports for mid-temperature H 2S removal. MCM-41 was synthesized as micrometric (MCM41_M) and nanometric (MCM41_N) particles and impregnated through an efficient two-solvent (hexane–water) procedure to obtain the corresponding γ-Fe 2O 3@MCM-41 composites. The active phase is homogeneously dispersed within the 2 nm channels in the form of ultrasmall maghemite nanoparticles assuring a high active phase reactivity. The final micrometric (Fe_MCM41_M) and nanometric (Fe_MCM41_N) composites were tested as sorbents for hydrogen sulphide removal at 300 °C and the results weremore » compared with a reference sorbent (commercial unsupported ZnO) and an analogous silica-based sorbent (Fe_SBA15). MCM-41 based sorbents, having the highest surface areas, showed superior performances that were retained after the first sulphidation cycle. Specifically, the micrometric sorbent (Fe_MCM41_M) showed a higher SRC value than the nanometric one (Fe_MCM41_N), due to the low stability of the nanosized particles over time caused by their high reactivity. Finally and furthermore, the low regeneration temperature (300–350 °C), besides the high removal capacity, renders MCM41-based systems an alternative class of regenerable sorbents for thermally efficient cleaning up processes in Integrated Gasification Combined Cycles (IGCC) systems.« less

MCM-41 support for ultrasmall γ-Fe 2O 3 nanoparticles for H 2S removal

DOE PAGES

Cara, C.; Rombi, E.; Musinu, A.; ...

2017-07-08

In this paper, MCM-41 is proposed to build mesostructured Fe 2O 3-based sorbents as an alternative to other silica or alumina supports for mid-temperature H 2S removal. MCM-41 was synthesized as micrometric (MCM41_M) and nanometric (MCM41_N) particles and impregnated through an efficient two-solvent (hexane–water) procedure to obtain the corresponding γ-Fe 2O 3@MCM-41 composites. The active phase is homogeneously dispersed within the 2 nm channels in the form of ultrasmall maghemite nanoparticles assuring a high active phase reactivity. The final micrometric (Fe_MCM41_M) and nanometric (Fe_MCM41_N) composites were tested as sorbents for hydrogen sulphide removal at 300 °C and the results weremore » compared with a reference sorbent (commercial unsupported ZnO) and an analogous silica-based sorbent (Fe_SBA15). MCM-41 based sorbents, having the highest surface areas, showed superior performances that were retained after the first sulphidation cycle. Specifically, the micrometric sorbent (Fe_MCM41_M) showed a higher SRC value than the nanometric one (Fe_MCM41_N), due to the low stability of the nanosized particles over time caused by their high reactivity. Finally and furthermore, the low regeneration temperature (300–350 °C), besides the high removal capacity, renders MCM41-based systems an alternative class of regenerable sorbents for thermally efficient cleaning up processes in Integrated Gasification Combined Cycles (IGCC) systems.« less

Efficient adsorption concentration and photolysis of acetaldehyde on titania-mesoporous silica composite

NASA Astrophysics Data System (ADS)

Yamaguchi, Satoshi; Matsumoto, Akihiko

2017-07-01

Titania-mesoporous silica composite (TiO2/MCM) was prepared by hydrolysis of titaniumtetraisopropoxide (TTIP) with the presence of mesoporous silica MCM-41. The TiO2/MCM samples consisted of highly dispersed TiO2 on the surface of MCM-41. Dynamic adsorption and photocatalytic decomposition features for acetaldehyde (CH3CHO) were measured by flow method. The amount of CH3CHO decomposition on TiO2/MCM-41 increased with the TiO2 amount, suggesting that a large amount of CH3CHO was adsorbed on mesopores of MCM-41 of the TiO2/MCM and was efficiently decomposed on finely dispersed TiO2 surface by ultraviolet irradiation.

Dry soldering with hot filament produced atomic hydrogen

DOEpatents

Panitz, Janda K. G.; Jellison, James L.; Staley, David J.

1995-01-01

A system for chemically transforming metal surface oxides to metal that is especially, but not exclusively, suitable for preparing metal surfaces for dry soldering and solder reflow processes. The system employs one or more hot, refractory metal filaments, grids or surfaces to thermally dissociate molecular species in a low pressure of working gas such as a hydrogen-containing gas to produce reactive species in a reactive plasma that can chemically reduce metal oxides and form volatile compounds that are removed in the working gas flow. Dry soldering and solder reflow processes are especially applicable to the manufacture of printed circuit boards, semiconductor chip lead attachment and packaging multichip modules. The system can be retrofitted onto existing metal treatment ovens, furnaces, welding systems and wave soldering system designs.

Planned development of a 3D computer based on free-space optical interconnects

NASA Astrophysics Data System (ADS)

Neff, John A.; Guarino, David R.

1994-05-01

Free-space optical interconnection has the potential to provide upwards of a million data channels between planes of electronic circuits. This may result in the planar board and backplane structures of today giving away to 3-D stacks of wafers or multi-chip modules interconnected via channels running perpendicular to the processor planes, thereby eliminating much of the packaging overhead. Three-dimensional packaging is very appealing for tightly coupled fine-grained parallel computing where the need for massive numbers of interconnections is severely taxing the capabilities of the planar structures. This paper describes a coordinated effort by four research organizations to demonstrate an operational fine-grained parallel computer that achieves global connectivity through the use of free space optical interconnects.

Dry-film polymer waveguide for silicon photonics chip packaging.

PubMed

Hsu, Hsiang-Han; Nakagawa, Shigeru

2014-09-22

Polymer waveguide made by dry film process is demonstrated for silicon photonics chip packaging. With 8 μm × 11.5 μm core waveguide, little penalty is observed up to 25 Gbps before or after the light propagate through a 10-km long single-mode fiber (SMF). Coupling loss to SMF is 0.24 dB and 1.31 dB at the polymer waveguide input and output ends, respectively. Alignment tolerance for 0.5 dB loss increase is +/- 1.0 μm along both vertical and horizontal directions for the coupling from the polymer waveguide to SMF. The dry-film polymer waveguide demonstrates promising performance for silicon photonics chip packaging used in next generation optical multi-chip module.

Chip-on-Board Technology 1996 Year-end Report (Design, Manufacturing, and Reliability Study)

NASA Technical Reports Server (NTRS)

Le, Binh Q.; Nhan, Elbert; Maurer, Richard H.; Lew, Ark L.; Lander, Juan R.

1996-01-01

The major impetus for flight qualifying Chip-On-Board (COB) packaging technology is the shift in emphasis for space missions to smaller, better, and cheaper spacecraft and satellites resulting from the NASA New Millenium initiative and similar requirements in DoD-sponsored programs. The most important benefit that can potentially be derived from miniaturizing spacecraft and satellites is the significant cost saving realizable if a smaller launch vehicle may be employed. Besides the program cost saving, there are several other advantages to building COB-based space hardware. First, once a well-controlled process is established, COB can be low cost compared to standard Multi-Chip Module (MCM) technology. This cost competitiveness is regarded as a result of the generally greater availability and lower cost of Known Good Die (KGD). Coupled with the elimination of the first level of packaging (chip package), compact, high-density circuit boards can be realized with Printed Wiring Boards (PWB) that can now be made with ever-decreasing feature size in line width and via hole. Since the COB packaging technique in this study is based mainly on populating bare dice on a suitable multi-layer laminate substrate which is not hermetically sealed, die coating for protection from the environment is required. In recent years, significant improvements have been made in die coating materials which further enhance the appeal of COB. Hysol epoxies, silicone, parylene and silicon nitride are desirable because of their compatible Thermal Coefficient of Expansion (TCE) and good moisture resistant capability. These die coating materials have all been used in the space and other industries with varying degrees of success. COB technology, specifically siliconnitride coated hardware, has been flown by Lockheed on the Polar satellite. In addition, DARPA has invested a substantial amount of resources on MCM and COB-related activities recently. With COB on the verge of becoming a dominant player in DoD programs, DARPA is increasing its support of the availability of KGDs which will help decrease their cost. Aside from the various major developments and trends in the space and defense industries that are favorable to the acceptance and widespread use of'COB packaging technology, implementing COB can be appealing in other aspects. Since the interconnection interface is usually the weak link in a system, the overall circuit or system reliability may actually be improved because of the elimination of a level of interconnect/packaging at the chip. With COB, mixing packaging technologies is possible. Because some devices are only available in commercial plastic packages, populating a multi-layer laminate substrate with both bare dice and plastic-package parts is inevitable. Another attractive feature of COB is that re-workability is possible if die coating is applied only on the die top. This method allows local replacement of individual dice that were found to be defective instead of replacing an entire board. In terms of thermal management, unpackaged devices offer a shorter thermal resistance path than their packaged counterparts thereby improving thermal sinking and heat removal from the parts.

Comparison of minichromosome maintenance proteins (MCM-3, MCM-7) and metallothioneins (MT-I/II, MT-III) expression in relation to clinicopathological data in ovarian cancer.

PubMed

Kobierzycki, Christopher; Pula, Bartosz; Skiba, Mateusz; Jablonska, Karolina; Latkowski, Krzysztof; Zabel, Maciej; Nowak-Markwitz, Ewa; Spaczynski, Marek; Kedzia, Witold; Podhorska-Okolow, Marzena; Dziegiel, Piotr

2013-12-01

Despite great progress in the understanding of ovarian cancer biology, clinicopathological data (i.e. grade, stage, histological type and residual disease after surgery) seem to be the most important prognostic factors. The present study aimed to investigate the relationship between expression of minichromosome maintenance proteins (MCM-3, MCM-7), metallothioneins (MT-I/II, MT-III), and Ki-67 in 103 ovarian cancer cases, mostly of the serous histological type. Statistical analysis revealed strong positive correlations in the expression of MCM-3 vs. Ki-67 (r=0.492), MCM-7 vs. Ki-67 (r=0.651), and MCM-3 vs. MCM-7 (r=0.515) (all p<0.0001). The Kruskal-Wallis test showed an association of increased expression of MCM-3 and Ki-67 with increasing grade of histological malignancy (p=0.0011, p=0.029, respectively). Regarding clinical progression, cytoplasmic MT-I/II expression was significantly higher in more advanced disease stages (III+IV vs. I+II; p=0.0247). Due to the correlations shown here, the determination of MCM proteins as proliferation markers of ovarian cancer, should be strongly considered.

Aminopropyl groups of the functionalized Mobil Crystalline Material 41 as a carrier for controlled diclofenac sodium and piroxicam delivery

PubMed Central

Khodaverdi, Elham; Ahmadi, Mina; Kamali, Hossein; Hadizadeh, Farzin

2017-01-01

Objective: Synthetic Mobil Crystalline Material 41 (MCM-41) as a mesoporous material and functionalized MCM-41 using aminopropyl groups were studied in order to investigate their ability to encapsulate and to control the release of diclofenac sodium and piroxicam. Materials and Methods: MCM-41 was synthesized through sol–gel procedure and functionalized with aminopropyl groups. The physicochemical properties of MCM-41 were studied through particle size analysis, infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and carbon–hydrogen–nitrogen analysis. Diclofenac sodium and piroxicam were loaded into the MCM-41 matrix using the filtration and solvent evaporation methods. The drug-loading capacity was determined by ultraviolet, Fourier transform infrared, X-ray diffraction, and Brunauer–Emmett–Teller analysis. Results: According to the results for pure drug release, >57% was released in the 1st h, but when these drugs were loaded into pure Mobil Crystalline Material 41 (MCM-41) and functionalized MCM-41, the release into the simulated gastrointestinal medium was less, continuous, and slower. The release of piroxicam from functionalized MCM-41 was slower than that from MCM-41 in the simulated intestinal medium because of the formation of electrostatic bonds between piroxicam and the aminopropyl groups of the functionalized MCM-41. However, in the case of diclofenac sodium, there was no significant difference between pure MCM-41 and functionalized MCM-41. The difference between piroxicam and diclofenac sodium was due to the high solubility of diclofenac sodium in the intestinal medium (pH 6.8), which caused more rapid release from the matrixes than for piroxicam. Conclusion: Our findings indicate that, after functionalization of MCM-41, it could offer a good means of delivering controlled diclofenac sodium and piroxicam. PMID:29692976

Aminopropyl groups of the functionalized Mobil Crystalline Material 41 as a carrier for controlled diclofenac sodium and piroxicam delivery.

PubMed

Khodaverdi, Elham; Ahmadi, Mina; Kamali, Hossein; Hadizadeh, Farzin

2017-01-01

Synthetic Mobil Crystalline Material 41 (MCM-41) as a mesoporous material and functionalized MCM-41 using aminopropyl groups were studied in order to investigate their ability to encapsulate and to control the release of diclofenac sodium and piroxicam. MCM-41 was synthesized through sol-gel procedure and functionalized with aminopropyl groups. The physicochemical properties of MCM-41 were studied through particle size analysis, infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and carbon-hydrogen-nitrogen analysis. Diclofenac sodium and piroxicam were loaded into the MCM-41 matrix using the filtration and solvent evaporation methods. The drug-loading capacity was determined by ultraviolet, Fourier transform infrared, X-ray diffraction, and Brunauer-Emmett-Teller analysis. According to the results for pure drug release, >57% was released in the 1 st h, but when these drugs were loaded into pure Mobil Crystalline Material 41 (MCM-41) and functionalized MCM-41, the release into the simulated gastrointestinal medium was less, continuous, and slower. The release of piroxicam from functionalized MCM-41 was slower than that from MCM-41 in the simulated intestinal medium because of the formation of electrostatic bonds between piroxicam and the aminopropyl groups of the functionalized MCM-41. However, in the case of diclofenac sodium, there was no significant difference between pure MCM-41 and functionalized MCM-41. The difference between piroxicam and diclofenac sodium was due to the high solubility of diclofenac sodium in the intestinal medium (pH 6.8), which caused more rapid release from the matrixes than for piroxicam. Our findings indicate that, after functionalization of MCM-41, it could offer a good means of delivering controlled diclofenac sodium and piroxicam.

Study on thermal, mechanical and adsorption properties of amine-functionalized MCM-41/PMMA and MCM-41/PS nanocomposites prepared by ultrasonic irradiation.

PubMed

Mohammadnezhad, Gholamhossein; Abad, Saeed; Soltani, Roozbeh; Dinari, Mohammad

2017-11-01

In this study, two common industrial polymers, poly(methyl methacrylate) (PMMA) and polystyrene (PS), were incorporated into amine-functionalized MCM-41 mesoporous silica as reinforcement agents via an ultrasonic assisted method as a facile, fast, eco-friendly, and versatile synthetic tool. Amino functionalization of MCM-41 were performed by 3-aminopropyl triethoxysilane as a coupling agent and it is denoted as APTS-MCM-41. The obtained nanocomposites (NCs), APTS-MCM-41/PMMA and APTS-MCM-41/PS, were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning and transmission electron microscopies (SEM and TEM), and thermogravimetric analysis (TGA). Their mechanical properties were also probed via stress-strain curves and improved tensile properties were observed in the NCs relative to the neat polymers. Additionally, APTS-MCM-41/PMMA exhibited better mechanical properties than APTS-MCM-41/PS. Sorption studies were carried out on the two NCs and the effect of different process parameters, namely, pH, contact time, and initial Cd(II) concentration investigated in batch mode. Pseudo-second order and intraparticle diffusion models explain the Cd(II) kinetics more effectively for APTS-MCM-41/PMMA and APTS-MCM-41/PS, respectively. The adsorption isotherm data fitted well to Langmuir isotherm for both NCs and the maximum monolayer adsorption capacities were found to be 24.75mg/g and 10.42mg/g for APTS-MCM-41/PMMA and APTS-MCM-41/PS, respectively. The results demonstrate that the NCs show potential for use in adsorption of heavy metal ion such as Cd(II) from aqueous media. Copyright © 2017 Elsevier B.V. All rights reserved.

Minichromosome maintenance helicase paralog MCM9 is dispensible for DNA replication but functions in germ-line stem cells and tumor suppression.

PubMed

Hartford, Suzanne A; Luo, Yunhai; Southard, Teresa L; Min, Irene M; Lis, John T; Schimenti, John C

2011-10-25

Effective DNA replication is critical to the health and reproductive success of organisms. The six MCM2-7 proteins, which form the replicative helicase, are essential for high-fidelity replication of the genome. Many eukaryotes have a divergent paralog, MCM9, that was reported to be essential for loading MCM2-7 onto replication origins in the Xenopus oocyte extract system. To address the in vivo role of mammalian MCM9, we created and analyzed the phenotypes of mice with various mutations in Mcm9 and an intronic DNA replication-related gene Asf1a. Ablation of Mcm9 was compatible with cell proliferation and mouse viability, showing that it is nonessential for MCM2-7 loading or DNA replication. Mcm9 mutants underwent p53-independent embryonic germ-cell depletion in both sexes, with males also exhibiting defective spermatogonial stem-cell renewal. MCM9-deficient cells had elevated genomic instability and defective cell cycle reentry following replication stress, and mutant animals were prone to sex-specific cancers, most notably hepatocellular carcinoma in males. The phenotypes of mutant mice and cells suggest that MCM9 evolved a specialized but nonessential role in DNA replication or replication-linked quality-control mechanisms that are especially important for germ-line stem cells, and also for tumor suppression and genome maintenance in the soma.

Characterization of a Novel MMS-Sensitive Allele of Schizosaccharomyces pombe mcm4+

PubMed Central

Ranatunga, Nimna S.; Forsburg, Susan L.

2016-01-01

The minichromosome maintenance (MCM) complex is the conserved helicase motor of the eukaryotic replication fork. Mutations in the Mcm4 subunit are associated with replication stress and double strand breaks in multiple systems. In this work, we characterize a new temperature-sensitive allele of Schizosaccharomyces pombe mcm4+. Uniquely among known mcm4 alleles, this mutation causes sensitivity to the alkylation damaging agent methyl methanesulfonate (MMS). Even in the absence of treatment or temperature shift, mcm4-c106 cells show increased repair foci of RPA and Rad52, and require the damage checkpoint for viability, indicating genome stress. The mcm4-c106 mutant is synthetically lethal with mutations disrupting fork protection complex (FPC) proteins Swi1 and Swi3. Surprisingly, we found that the deletion of rif1+ suppressed the MMS-sensitive phenotype without affecting temperature sensitivity. Together, these data suggest that mcm4-c106 destabilizes replisome structure. PMID:27473316

The Mini-Chromosome Maintenance (Mcm) Complexes Interact with DNA Polymerase α-Primase and Stimulate Its Ability to Synthesize RNA Primers

PubMed Central

You, Zhiying; De Falco, Mariarosaria; Kamada, Katsuhiko; Pisani, Francesca M.; Masai, Hisao

2013-01-01

The Mini-chromosome maintenance (Mcm) proteins are essential as central components for the DNA unwinding machinery during eukaryotic DNA replication. DNA primase activity is required at the DNA replication fork to synthesize short RNA primers for DNA chain elongation on the lagging strand. Although direct physical and functional interactions between helicase and primase have been known in many prokaryotic and viral systems, potential interactions between helicase and primase have not been explored in eukaryotes. Using purified Mcm and DNA primase complexes, a direct physical interaction is detected in pull-down assays between the Mcm2∼7 complex and the hetero-dimeric DNA primase composed of the p48 and p58 subunits. The Mcm4/6/7 complex co-sediments with the primase and the DNA polymerase α-primase complex in glycerol gradient centrifugation and forms a Mcm4/6/7-primase-DNA ternary complex in gel-shift assays. Both the Mcm4/6/7 and Mcm2∼7 complexes stimulate RNA primer synthesis by DNA primase in vitro. However, primase inhibits the Mcm4/6/7 helicase activity and this inhibition is abolished by the addition of competitor DNA. In contrast, the ATP hydrolysis activity of Mcm4/6/7 complex is not affected by primase. Mcm and primase proteins mutually stimulate their DNA-binding activities. Our findings indicate that a direct physical interaction between primase and Mcm proteins may facilitate priming reaction by the former protein, suggesting that efficient DNA synthesis through helicase-primase interactions may be conserved in eukaryotic chromosomes. PMID:23977294

Mechanism insight of pollutant degradation and bromate inhibition by Fe-Cu-MCM-41 catalyzed ozonation.

PubMed

Chen, Weirui; Li, Xukai; Tang, Yiming; Zhou, Jialu; Wu, Dan; Wu, Yin; Li, Laisheng

2018-03-15

A flexible catalyst, Fe-Cu-MCM-41, was employed to enhance diclofenac (DCF) mineralization and inhibit bromate formation in catalytic ozonation process. Greater TOC removal was achieved in Fe-Cu-MCM-41/O 3 process (78%) than those in Fe-MCM-41/O 3 (65%), Cu-MCM-41/O 3 (73%) and sole ozonation (42%). But it was interesting that both Cu-MCM-41/O 3 and Fe-MCM-41/O 3 achieved 93% bromate inhibition efficiency, only 71% inhibition efficiency was observed in Fe-Cu-MCM-41/O 3 . Influence of pH, TBA/NaHSO 3 and detection of by-products were conducted to explore the mechanism. By Pyridine adsorption-IR and XPS, a relationship was found among activity of catalysts, Lewis acid sites and electron transfer effect between Fe (II/III) and Cu (I/II). Fe-Cu-MCM-41 promoted ozone decomposition to generate OH, which accounted for enhanced DCF mineralization. The consumption of aqueous O 3 also suppressed the oxidative of Br - and HBrO/Br - . More HBrO/BrO - accumulated in catalytic ozonation process and less bromate generated. Bromate formation in Fe-Cu-MCM-41/O 3 process was sensitive with pH value, the acidic condition was not favor for bromate formation. Both DCF mineralization and bromate inhibition were influenced by surface reaction. Moreover, Fe-Cu-MCM-41 showed excellent catalytic performance in suppressing the accumulation of carboxylic acid, especially for oxalic acid. Nearly no oxalic acid was detected during Fe-Cu-MCM-41/O 3 process. Copyright © 2017 Elsevier B.V. All rights reserved.

Application of mesoporous Al-MCM-48 material to the conversion of lignin.

PubMed

Lee, Hyung Won; Lee, In-Gu; Park, Sung Hoon; Jeon, Jong-Ki; Suh, Dong Jin; Jung, Jinho; Park, Young-Kwon

2014-04-01

Al-MCM-48 was applied to the catalytic pyrolysis of lignin for the first time. The pyrolysis reaction and in-situ product were analyzed by pyrolysis gas chromatography/mass spectrometry. The main products of the non-catalytic pyrolysis of lignin were phenols. The use of Al-MCM-48 increased the production of light phenols considerably. The yields of high-value-added compounds, such as hydrocarbons and aromatics, were also increased by catalytic upgrading. Al-MCM-48 is believed to promote cracking, aromatization and deoxygenation, such as decarbonylation. On the other hand, Si-MCM-48, which has no acid sites, showed lower deoxygenation efficiency than Al-MCM-48. Al-MCM-48 could be regenerated by calcining in air.

C. elegans MCM-4 is a general DNA replication and checkpoint component with an epidermis-specific requirement for growth and viability.

PubMed

Korzelius, Jerome; The, Inge; Ruijtenberg, Suzan; Portegijs, Vincent; Xu, Huihong; Horvitz, H Robert; van den Heuvel, Sander

2011-02-15

DNA replication and its connection to M phase restraint are studied extensively at the level of single cells but rarely in the context of a developing animal. C. elegans lin-6 mutants lack DNA synthesis in postembryonic somatic cell lineages, while entry into mitosis continues. These mutants grow slowly and either die during larval development or develop into sterile adults. We found that lin-6 corresponds to mcm-4 and encodes an evolutionarily conserved component of the MCM2-7 pre-RC and replicative helicase complex. The MCM-4 protein is expressed in all dividing cells during embryonic and postembryonic development and associates with chromatin in late anaphase. Induction of cell cycle entry and differentiation continues in developing mcm-4 larvae, even in cells that went through abortive division. In contrast to somatic cells in mcm-4 mutants, the gonad continues DNA replication and cell division until late larval development. Expression of MCM-4 in the epidermis (also known as hypodermis) is sufficient to rescue the growth retardation and lethality of mcm-4 mutants. While the somatic gonad and germline show substantial ability to cope with lack of zygotic mcm-4 function, mcm-4 is specifically required in the epidermis for growth and survival of the whole organism. Thus, C. elegans mcm-4 has conserved functions in DNA replication and replication checkpoint control but also shows unexpected tissue-specific requirements. Copyright © 2010 Elsevier Inc. All rights reserved.

C. elegans MCM-4 is a general DNA replication and checkpoint component with an epidermis-specific requirement for growth and viability

PubMed Central

Korzelius, Jerome; The, Inge; Ruijtenberg, Suzan; Portegijs, Vincent; Xu, Huihong; Horvitz, H. Robert; van den Heuvel, Sander

2012-01-01

DNA replication and its connection to M phase restraint are studied extensively at the level of single cells but rarely in the context of a developing animal. C. elegans lin-6 mutants lack DNA synthesis in postembryonic somatic cell lineages, while entry into mitosis continues. These mutants grow slowly and either die during larval development or develop into sterile adults. We found that lin-6 corresponds to mcm-4 and encodes an evolutionarily conserved component of the MCM2-7 pre-RC and replicative helicase complex. The MCM-4 protein is expressed in all dividing cells during embryonic and postembryonic development and associates with chromatin in late anaphase. Induction of cell-cycle entry and differentiation continues in developing mcm-4 larvae, even in cells that went through abortive division. In contrast to somatic cells in mcm-4 mutants, the gonad continues DNA replication and cell division until late larval development. Expression of MCM-4 in the epidermis (also known as hypodermis) is sufficient to rescue the growth retardation and lethality of mcm-4 mutants. While the somatic gonad and germline show substantial ability to cope with lack of zygotic mcm-4 function, mcm-4 is specifically required in the epidermis for growth and survival of the whole organism. Thus, C. elegans mcm-4 has conserved functions in DNA replication and replication checkpoint control but also shows unexpected tissue-specific requirements. PMID:21146520

SiC-dopped MCM-41 materials with enhanced thermal and hydrothermal stabilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yingyong; Jin, Guoqiang; Tong, Xili

2011-11-15

Graphical abstract: Novel SiC-dopped MCM-41 materials were synthesized by adding silicon carbide suspension in the molecular sieve precursor solvent followed by in situ hydrothermal synthesis. The dopped materials have a wormhole-like mesoporous structure and exhibit enhanced thermal and hydrothermal stabilities. Highlights: {yields} SiC-dopped MCM-41 was synthesized by in situ hydrothermal synthesis of molecular sieve precursor combined with SiC. {yields} The dopped MCM-41 materials show a wormhole-like mesoporous structure. {yields} The thermal stability of the dopped materials have an increment of almost 100 {sup o}C compared with the pure MCM-41. {yields} The hydrothermal stability of the dopped materials is also bettermore » than that of the pure MCM-41. -- Abstract: SiC-dopped MCM-41 mesoporous materials were synthesized by the in situ hydrothermal synthesis, in which a small amount of SiC was added in the precursor solvent of molecular sieve before the hydrothermal treatment. The materials were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, N{sub 2} physical adsorption and thermogravimetric analysis, respectively. The results show that the thermal and hydrothermal stabilities of MCM-41 materials can be improved obviously by incorporating a small amount of SiC. The structure collapse temperature of SiC-dopped MCM-41 materials is 100 {sup o}C higher than that of pure MCM-41 according to the differential scanning calorimetry analysis. Hydrothermal treatment experiments also show that the pure MCM-41 will losses it's ordered mesoporous structure in boiling water for 24 h while the SiC-dopped MCM-41 materials still keep partial porous structure.« less

Cross flow ultrafiltration of Cr (VI) using MCM-41, MCM-48 and Faujasite (FAU) zeolite-ceramic composite membranes.

PubMed

Basumatary, Ashim Kumar; Kumar, R Vinoth; Ghoshal, Aloke Kumar; Pugazhenthi, G

2016-06-01

This work describes the removal of Cr (VI) from aqueous solution in cross flow mode using MCM-41, MCM-48 and FAU zeolite membranes prepared on circular shaped porous ceramic support. Ceramic support was manufactured using locally available clay materials via a facile uni-axial compaction method followed by sintering process. A hydrothermal technique was employed for the deposition of zeolites on the ceramic support. The porosity of ceramic support (47%) is reduced by the formation of MCM-41 (23%), MCM-48 (22%) and FAU (33%) zeolite layers. The pore size of the MCM-41, MCM-48 and FAU membrane is found to be 0.173, 0.142, and 0.153 μm, respectively, which is lower than that of the support (1.0 μm). Cross flow ultrafiltration experiments of Cr (VI) were conducted at five different applied pressures (69-345 kPa) and three cross flow rates (1.11 × 10(-7) - 2.22 × 10(-7) m(3)/s). The filtration studies inferred that the performance of the fabricated zeolite composite membranes is optimum at the maximum applied pressure (345 kPa) and the highest rejection is obtained with the lowest cross flow rate (1.11 × 10(-7) m(3)/s) for all three zeolite membrane. The permeate flux of MCM-41, MCM-48 and FAU zeolite composite membranes are almost remained constant in the entire duration of the separation process. The highest removal of 82% is shown by FAU membrane, while MCM-41 and MCM-48 display 75% and 77% of Cr (VI) removal, respectively for the initial feed concentration of 1000 ppm with natural pH of the solution at an applied pressure of 345 kPa. Copyright © 2016 Elsevier Ltd. All rights reserved.

Cerium incorporated MCM-48 (Ce-MCM-48) as a catalyst to inhibit bromate formation during ozonation of bromide-containing water: Efficacy and mechanism.

PubMed

Li, Weiwei; Lu, Xiaowei; Xu, Ke; Qu, Jiuhui; Qiang, Zhimin

2015-12-01

The composite mesoporous sieve Ce-MCM-48 (cerium incorporated MCM-48) with different Si/Ce molar ratios were synthesized hydrothermally and characterized with X-ray diffraction, X-ray photoelectron spectroscopy, BET surface area, and pHpzc. Results indicate that Ce-MCM-48, especially with a Si/Ce molar ratio of 66 (i.e., Ce66-MCM-48), could significantly inhibit bromate (BrO3(-)) formation during ozonation of Br(-)-containing water, achieving 91% of inhibition efficiency at pH 7.6 and 25 °C. An acidic or alkaline pH decreased the inhibition efficiency of Ce66-MCM-48 to some extent, but reaction temperature ranging from 15 to 30 °C had no significant impact. By comparing the bromine mass balance, aqueous O3 decomposition, and newly formed H2O2 between O3 and O3/Ce66-MCM-48 processes, the inhibition mechanism was proposed: Ce66-MCM-48 promoted aqueous O3 decomposition to generate hydroxyl radicals (OH) that could merge into H2O2, so the oxidative transformation of Br(-) and HOBr/OBr(-) by O3 and OH was primarily suppressed. The catalytic ability of Ce66-MCM-48 was continuously regenerated through the circulating reactions between Ce(III) and Ce(IV) occurring on the catalyst surface. Besides its inhibition on BrO3(-) formation, Ce66-MCM-48 could also enhance the degradation of refractory organic micropollutants. Because of these distinct merits, Ce66-MCM-48 has potential applications to water treatment by ozone. Copyright © 2015 Elsevier Ltd. All rights reserved.

Identification and Characterization of MCM3 as a Kelch-like ECH-associated Protein 1 (KEAP1) Substrate*

PubMed Central

Mulvaney, Kathleen M.; Matson, Jacob P.; Siesser, Priscila F.; Tamir, Tigist Y.; Goldfarb, Dennis; Jacobs, Timothy M.; Cloer, Erica W.; Harrison, Joseph S.; Vaziri, Cyrus; Cook, Jeanette G.; Major, Michael B.

2016-01-01

KEAP1 is a substrate adaptor protein for a CUL3-based E3 ubiquitin ligase. Ubiquitylation and degradation of the antioxidant transcription factor NRF2 is considered the primary function of KEAP1; however, few other KEAP1 substrates have been identified. Because KEAP1 is altered in a number of human pathologies and has been proposed as a potential therapeutic target therein, we sought to better understand KEAP1 through systematic identification of its substrates. Toward this goal, we combined parallel affinity capture proteomics and candidate-based approaches. Substrate-trapping proteomics yielded NRF2 and the related transcription factor NRF1 as KEAP1 substrates. Our targeted investigation of KEAP1-interacting proteins revealed MCM3, an essential subunit of the replicative DNA helicase, as a new substrate. We show that MCM3 is ubiquitylated by the KEAP1-CUL3-RBX1 complex in cells and in vitro. Using ubiquitin remnant profiling, we identify the sites of KEAP1-dependent ubiquitylation in MCM3, and these sites are on predicted exposed surfaces of the MCM2–7 complex. Unexpectedly, we determined that KEAP1 does not regulate total MCM3 protein stability or subcellular localization. Our analysis of a KEAP1 targeting motif in MCM3 suggests that MCM3 is a point of direct contact between KEAP1 and the MCM hexamer. Moreover, KEAP1 associates with chromatin in a cell cycle-dependent fashion with kinetics similar to the MCM2–7 complex. KEAP1 is thus poised to affect MCM2–7 dynamics or function rather than MCM3 abundance. Together, these data establish new functions for KEAP1 within the nucleus and identify MCM3 as a novel substrate of the KEAP1-CUL3-RBX1 E3 ligase. PMID:27621311

Effect of template in MCM-41 on the adsorption of aniline from aqueous solution.

PubMed

Yang, Xinxin; Guan, Qingxin; Li, Wei

2011-11-01

The effect of the surfactant template cetyltrimethylammonium bromide (CTAB) in MCM-41 on the adsorption of aniline was investigated. Various MCM-41 samples were prepared by controlling template removal using an extraction method. The samples were then used as adsorbents for the removal of aniline from aqueous solution. The results showed that the MCM-41 samples with the template partially removed (denoted as C-MCM-41) exhibited better adsorption performance than MCM-41 with the template completely removed (denoted as MCM-41). The reason for this difference may be that the C-MCM-41 samples had stronger hydrophobic properties and selectivity for aniline because of the presence of the template. The porosity and cationic sites generated by the template play an important role in the adsorption process. The optimal adsorbent with moderate template was achieved by changing the ratio of extractant; it has the potential for promising applications in the field of water pollution control. Copyright © 2011 Elsevier Ltd. All rights reserved.

Structural basis for DNA binding by replication initiator Mcm10

DOE Office of Scientific and Technical Information (OSTI.GOV)

Warren, Eric M.; Vaithiyalingam, Sivaraja; Haworth, Justin

2009-06-30

Mcm10 is an essential eukaryotic DNA replication protein required for assembly and progression of the replication fork. The highly conserved internal domain (Mcm10-ID) has been shown to physically interact with single-stranded (ss) DNA, DNA polymerase alpha, and proliferating cell nuclear antigen (PCNA). The crystal structure of Xenopus laevis Mcm10-ID presented here reveals a DNA binding architecture composed of an oligonucleotide/oligosaccharide-fold followed in tandem by a variant and highly basic zinc finger. NMR chemical shift perturbation and mutational studies of DNA binding activity in vitro reveal how Mcm10 uses this unique surface to engage ssDNA. Corresponding mutations in Saccharomyces cerevisiae resultmore » in increased sensitivity to replication stress, demonstrating the functional importance of DNA binding by this region of Mcm10 to replication. In addition, mapping Mcm10 mutations known to disrupt PCNA, polymerase alpha, and DNA interactions onto the crystal structure provides insight into how Mcm10 might coordinate protein and DNA binding within the replisome.« less

Amino-functionalized MCM-41 and MCM-48 for the removal of chromate and arsenate.

PubMed

Benhamou, A; Basly, J P; Baudu, M; Derriche, Z; Hamacha, R

2013-08-15

The aim of the present work was to investigate the efficiency of three amino-functionalized (hexadecylamine, dodecylamine, and dimethyldodecylamine) mesoporous silicas (MCM-41 and MCM-48) toward the adsorption of arsenate and chromate. Hexadecylamine-functionalized materials were characterized; BET surface areas, pore volumes, and sizes decreased with the functionalization, whereas XRD patterns show that the hexagonal structure of MCM-41 and the cubic structure of MCM-48 were not modified. The zeta potential decreases with pH and the highest arsenate and chromate removal was observed at the lowest pHs. Adsorption of chromium and arsenate was significantly enhanced after functionalization and amino-functionalized MCM-41 adsorb larger amounts of arsenate when compared to expanded MCM-48 materials. Chromate sorption capacities increased with the chain length and the larger capacities were obtained with hexadecylamine-functionalized mesoporous silicas. Mesoporous silicas modified by dimethyldodecylamine exhibited the higher arsenate sorption capacities. Copyright © 2013 Elsevier Inc. All rights reserved.

Synthesis of Dicyclopentadiene Oligomer Over Nanoporous Al-MCM-41 Catalysts.

PubMed

Park, Eunseo; Kim, Jinhan; Yim, Jin-Heong; Han, Jeongsik; Kwon, Tae Soo; Park, Y K; Jeon, Jong-Ki

2016-05-01

One step reaction composed of DCPD oligomerization and DCPD oligomer isomerization was investigated over nanoporous Al-MCM-41 catalysts. The effects of aluminum grafting over MCM-41 on the catalyst characteristics were studied with respect to the synthesis of TCPD isomer. Physical and chemical properties of the catalysts were analyzed by N2 adsorption, temperature-programmed desorption of ammonia, and infrared spectroscopy of adsorbed pyridine. The overall number of acid sites as well as the number of Lewis acid sites increased with increasing of aluminum content over MCM-41. When utilizing MCM-41 and Al-MCM-41 as the catalyst, DCPD oligomerization reaction activity greatly increased compared to the thermal reaction. The highest TCPD isomer selectivity over the Al-MCM-41 catalyst with the highest aluminum content could be ascribed to the largest amount of acid sites. This study showed an increased level of TCPD isomer selectivity by an increasing level of Lewis acid sites through aluminum addition over MCM-41.

Enhanced thermaly managed packaging for III-nitride light emitters

NASA Astrophysics Data System (ADS)

Kudsieh, Nicolas

In this Dissertation our work on `enhanced thermally managed packaging of high power semiconductor light sources for solid state lighting (SSL)' is presented. The motivation of this research and development is to design thermally high stable cost-efficient packaging of single and multi-chip arrays of III-nitrides wide bandgap semiconductor light sources through mathematical modeling and simulations. Major issues linked with this technology are device overheating which causes serious degradation in their illumination intensity and decrease in the lifetime. In the introduction the basics of III-nitrides WBG semiconductor light emitters are presented along with necessary thermal management of high power cingulated and multi-chip LEDs and laser diodes. This work starts at chip level followed by its extension to fully packaged lighting modules and devices. Different III-nitride structures of multi-quantum well InGaN/GaN and AlGaN/GaN based LEDs and LDs were analyzed using advanced modeling and simulation for different packaging designs and high thermal conductivity materials. Study started with basic surface mounted devices using conventional packaging strategies and was concluded with the latest thermal management of chip-on-plate (COP) method. Newly discovered high thermal conductivity materials have also been incorporated for this work. Our study also presents the new approach of 2D heat spreaders using such materials for SSL and micro LED array packaging. Most of the work has been presented in international conferences proceedings and peer review journals. Some of the latest work has also been submitted to well reputed international journals which are currently been reviewed for publication. .

Synthesis and stability of L-tryptophan adsorbed on Ti/MCM-41 as a catalyst for the regioselective aminolysis of styrene oxide

NASA Astrophysics Data System (ADS)

Aghapoor, Kioumars; Amini, Mostafa M.; Jadidi, Khosrow; Mohsenzadeh, Farshid; Darabi, Hossein Reza; Sayahi, Hani; Jalali, Mohammad Reza

2015-11-01

L-tryptophan is adsorbed on the titania surface of Ti/MCM-41 (L-tryp≡Ti/MCM-41) as a novel material via two steps. Ti/MCM-41 was first prepared by grafting TiCl4 on activated MCM-41 mesoporous silica in an anhydrous THF. Subsequent adsorption of L-tryptophan on the surface of grafted Ti sites from an aqueous solution afforded L-tryp≡Ti/MCM-41. Characterization of the material was carried out with thermogravimetric and differential thermogravimetric analyses, powder X-ray diffraction, BET and BJH nitrogen adsorption-desorption methods, Fourier transform infrared, UV-Visible, and energy dispersive X-ray spectroscopes. The results indicate that the adsorption of L-tryptophan on the surface of Ti/MCM-41 occurred. L-tryp≡Ti/MCM-41 was applied successfully as a heterogeneous catalyst for the ring opening of styrene oxide with aniline derivatives and demonstrated high to excellent activity and regioselectivity under microwave irradiation and solvent-free conditions. This thermal-resistant catalyst can be recycled at least five times without appreciable loss of activity, which confirms the strong adsorption of L-tryptophan on Ti/MCM-41.

Phosphopeptide binding by Sld3 links Dbf4-dependent kinase to MCM replicative helicase activation.

PubMed

Deegan, Tom D; Yeeles, Joseph Tp; Diffley, John Fx

2016-05-02

The initiation of eukaryotic DNA replication requires the assembly of active CMG (Cdc45-MCM-GINS) helicases at replication origins by a set of conserved and essential firing factors. This process is controlled during the cell cycle by cyclin-dependent kinase (CDK) and Dbf4-dependent kinase (DDK), and in response to DNA damage by the checkpoint kinase Rad53/Chk1. Here we show that Sld3, previously shown to be an essential CDK and Rad53 substrate, is recruited to the inactive MCM double hexamer in a DDK-dependent manner. Sld3 binds specifically to DDK-phosphorylated peptides from two MCM subunits (Mcm4, 6) and then recruits Cdc45. MCM mutants that cannot bind Sld3 or Sld3 mutants that cannot bind phospho-MCM or Cdc45 do not support replication. Moreover, phosphomimicking mutants in Mcm4 and Mcm6 bind Sld3 without DDK and facilitate DDK-independent replication. Thus, Sld3 is an essential "reader" of DDK phosphorylation, integrating signals from three distinct protein kinase pathways to coordinate DNA replication during S phase. © 2016 The Authors. Published under the terms of the CC BY 4.0 license.

MCM Paradox: Abundance of Eukaryotic Replicative Helicases and Genomic Integrity.

PubMed

Das, Mitali; Singh, Sunita; Pradhan, Satyajit; Narayan, Gopeshwar

2014-01-01

As a crucial component of DNA replication licensing system, minichromosome maintenance (MCM) 2-7 complex acts as the eukaryotic DNA replicative helicase. The six related MCM proteins form a heterohexamer and bind with ORC, CDC6, and Cdt1 to form the prereplication complex. Although the MCMs are well known as replicative helicases, their overabundance and distribution patterns on chromatin present a paradox called the "MCM paradox." Several approaches had been taken to solve the MCM paradox and describe the purpose of excess MCMs distributed beyond the replication origins. Alternative functions of these MCMs rather than a helicase had also been proposed. This review focuses on several models and concepts generated to solve the MCM paradox coinciding with their helicase function and provides insight into the concept that excess MCMs are meant for licensing dormant origins as a backup during replication stress. Finally, we extend our view towards the effect of alteration of MCM level. Though an excess MCM constituent is needed for normal cells to withstand stress, there must be a delineation of the threshold level in normal and malignant cells. This review also outlooks the future prospects to better understand the MCM biology.

MCM Paradox: Abundance of Eukaryotic Replicative Helicases and Genomic Integrity

PubMed Central

Das, Mitali; Singh, Sunita; Pradhan, Satyajit

2014-01-01

As a crucial component of DNA replication licensing system, minichromosome maintenance (MCM) 2–7 complex acts as the eukaryotic DNA replicative helicase. The six related MCM proteins form a heterohexamer and bind with ORC, CDC6, and Cdt1 to form the prereplication complex. Although the MCMs are well known as replicative helicases, their overabundance and distribution patterns on chromatin present a paradox called the “MCM paradox.” Several approaches had been taken to solve the MCM paradox and describe the purpose of excess MCMs distributed beyond the replication origins. Alternative functions of these MCMs rather than a helicase had also been proposed. This review focuses on several models and concepts generated to solve the MCM paradox coinciding with their helicase function and provides insight into the concept that excess MCMs are meant for licensing dormant origins as a backup during replication stress. Finally, we extend our view towards the effect of alteration of MCM level. Though an excess MCM constituent is needed for normal cells to withstand stress, there must be a delineation of the threshold level in normal and malignant cells. This review also outlooks the future prospects to better understand the MCM biology. PMID:25386362

Flexible DNA Path in the MCM Double Hexamer Loaded on DNA.

PubMed

Hizume, Kohji; Kominami, Hiroaki; Kobayashi, Kei; Yamada, Hirofumi; Araki, Hiroyuki

2017-05-16

The formation of the pre-replicative complex (pre-RC) during the G1 phase, which is also called the licensing of DNA replication, is the initial and essential step of faithful DNA replication during the subsequent S phase. It is widely accepted that in the pre-RC, double-stranded DNA passes through the holes of two ring-shaped minichromosome maintenance (MCM) 2-7 hexamers; however, the spatial organization of the DNA and proteins involved in pre-RC formation is unclear. Here we reconstituted the pre-RC from purified DNA and proteins and visualized the complex using atomic force microscopy (AFM). AFM revealed that the MCM double hexamers formed elliptical particles on DNA. Analysis of the angle of binding of DNA to the MCM double hexamer suggests that the DNA does not completely pass through both holes of the MCM hexamers, possibly because the DNA exited from the gap between Mcm2 and Mcm5. A DNA loop fastened by the MCM double hexamer was detected in pre-RC samples reconstituted from purified proteins as well as those purified from yeast cells, suggesting a higher-order architecture of the loaded MCM hexamers and DNA strands.

Performance assessment of MCM-48 ceramic composite membrane by separation of AlCl3 from aqueous solution.

PubMed

Kumar Basumatary, Ashim; Kumar Ghoshal, Aloke; Pugazhenthi, G

2016-12-01

Three dimensional ordered mesoporous MCM-48 membrane was fabricated on a circular shaped ceramic support by in-situ hydrothermal method. The synthesized MCM-48 powder and MCM-48 ceramic composite membrane were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA) and field emission scanning electron microscopy (FESEM). The porosity and pore size of the composite membrane are reduced considerably by the deposition of MCM-48 on the support. The formation of MCM-48 is verified by the XRD analysis. Three stepwise mechanisms for surfactant removal are observed by TGA analysis. FESEM images clearly signify the deposition of MCM-48 on the ceramic support. The pure water flux of the support and MCM-48 composite membrane is found to be 3.63×10 -6 and 4.18×10 -8 m 3 /m 2 skPa, respectively. The above prepared MCM-48 ceramic composite membrane is employed for the removal of AlCl 3 from aqueous solution and the highest rejection of 81% is obtained at an applied pressure of 276kPa with salt concentration of 250ppm. Copyright © 2015 Elsevier Inc. All rights reserved.

Peculiar behavior of MWW materials in aldol condensation of furfural and acetone.

PubMed

Kikhtyanin, Oleg; Chlubná, Pavla; Jindrová, Tereza; Kubička, David

2014-07-21

MWW family of different structural types (MCM-22, MCM-49, MCM-56 and MCM-36) was used as catalysts for aldol condensation of furfural and acetone studied in a batch reactor at 100 °C, autogenous pressure and a reaction time of 0-4 h. To establish a relation between physico-chemical and catalytic properties of microporous materials, the samples were characterized by XRD, SEM, N2 adsorption, FTIR and TGA. It was found that the acidic solids possessed appreciable activity in the reaction and resulted in the formation of products of aldehyde-ketone interaction. Surprisingly, MCM-22 and MCM-49, i.e. three-dimensional materials containing internal supercages, exhibited higher activity than two MCM-36 catalysts with two-dimensional character having larger accessible external surface area due to expansion of the interlayer space by swelling and pillaring treatments. Moreover, all MWW family catalysts gave higher conversion than the large-pore zeolite BEA. Nevertheless, furfural conversion decreased rapidly for all the studied materials due to coke formation. Unexpectedly, the deactivation was found to be more severe for MCM-36 catalysts than for MCM-22 and MCM-49, which was attributed to the reaction taking place also in supercages that are protected by 10-ring channels from severe coking. In contrast the cups located on the external surface were coked rapidly.

Characterization of the MCM homohexamer from the thermoacidophilic euryarchaeon Picrophilus torridus

PubMed Central

Goswami, Kasturi; Arora, Jasmine; Saha, Swati

2015-01-01

The typical archaeal MCM exhibits helicase activity independently in vitro. This study characterizes MCM from the euryarchaeon Picrophilus torridus. While PtMCM hydrolyzes ATP in DNA-independent manner, it displays very poor ability to unwind DNA independently, and then too only under acidic conditions. The protein exists stably in complex with PtGINS in whole cell lysates, interacting directly with PtGINS under neutral and acidic conditions. GINS strongly activates MCM helicase activity, but only at low pH. In consonance with this, PtGINS activates PtMCM-mediated ATP hydrolysis only at low pH, with the amount of ATP hydrolyzed during the helicase reaction increasing more than fifty-fold in the presence of GINS. While the stimulation of MCM-mediated helicase activity by GINS has been reported in MCMs from P.furiosus, T.kodakarensis, and very recently, T.acidophilum, to the best of our knowledge, this is the first report of an MCM helicase demonstrating DNA unwinding activity only at such acidic pH, across all archaea and eukaryotes. PtGINS may induce/stabilize a conducive conformation of PtMCM under acidic conditions, favouring PtMCM-mediated DNA unwinding coupled to ATP hydrolysis. Our findings underscore the existence of divergent modes of replication regulation among archaea and the importance of investigating replication events in more archaeal organisms. PMID:25762096

A conjunctive use hydrologic model for a semi-arid region with irrigated agriculture

NASA Astrophysics Data System (ADS)

Ruud, N. C.; Harter, T.

2003-04-01

A GIS-based sub-basin scale conjunctive use (CU) model is developed for a semi-arid agricultural area in the southern San Joaquin Valley, California. The study area is 2230 square kilometers, and consists of 9114 individual landuse units and 26 water service districts. The CU model consists of three sub-models: 1) a surface water supply (SWS) model, 2) an unsaturated zone water budget (UZWB) model, and 3) a groundwater flow model. The study period is 1970-99. For each modeled surface water channel, the SWS model computes monthly surface water deliveries to each district and conveyance losses due to evaporation and seepage. The UZWB model then calculates the monthly water storage changes in the soil root zone and deep vadose zone of each landuse unit. The UZWB model is driven by surface water applications, precipitation, and crop consumptive use (evapotranspiration) demands. Its outputs are the recharge to the unconfined aquifer and the groundwater pumping demand from the unconfined and confined aquifers. The transient recharge and pumping rates become input for the groundwater flow model which calculates changes in unconfined aquifer water levels and inter-district groundwater fluxes. The groundwater flow model was calibrated against data from 1970-85 and validated with data from 1986-99. From 1970-99, a total of 18500 million cubic meters (MCM) of surface water was applied to land units in the study area. Precipitation added from 219 MCM (1990) to 1200 MCM (1998) annually. The combined total annual agricultural and urban consumptive use ranged from 1070 MCM in 1970 to 1540 MCM in 1999. Total annual channel seepage varied over almost two orders of magnitude from a low of 10 MCM in 1977 to 576 MCM in 1983. Diffuse recharge from surface applied water ranged from 79.9 MCM in 1992 to 432 MCM in 1983. The estimated total pumping ranged from 183 MCM in 1978 to 703 MCM in 1990. As expected, pumping was heaviest during the droughts of 1975-77 and 1987-92, and lightest during the wet years of 1973, 1978, 1982-83, 1995, and 1998. The study area cumulative annual groundwater storage changes were computed by the CU model and compared against those of the water-table fluctuation (WTF) method. Relative to 1970, the maximum groundwater accumulation occurred in 1987 with the WTF method and the CU model estimating positive storage changes of 1410 MCM and 1110 MCM. The maximum groundwater overdraft (storage depletion) occurred in 1993 with the WTF method and the CU model estimating negative storage changes of 1990 MCM and 1500 MCM. Annual inter-district net groundwater fluxes ranged from negligibly small (<0.123 MCM) to as much as 98.7 MCM between some of the larger districts.

Removal of Cu(II) and Pb(II) from Aqueous Solutions Using Nanoporous Materials

NASA Astrophysics Data System (ADS)

Dutta, Debajani; Roy, Sushanta Kumar; Das, Bodhaditya; Talukdar, Anup K.

2018-05-01

The present work deals with the adsorption of Cu2+ and Pb2+ on zeolites (ZSM-5, mordenite) and mesoporous materials (MCM-48, MCM-41). The characterization of the synthesized samples was performed by means of XRD, SEM, and thermogravimetric analysis. The batch method was employed to study the influence of adsorbent nature, contact time, initial metal ion concentration, and adsorbent load. The adsorption on MCM-48 follows a pseudo-second-order kinetic model. This material was found to be more effective for the removal of lead in a batch process as compared to the other adsorbents and the removal efficiency of the materials for Pb(II) followed the order MCM-48 > mordenite > ZSM-5 > MCM-41 and that for Cu(II) followed the order ZSM-5 > mordenite > MCM-41 > MCM-48.

The 1.8-Å crystal structure of the N-terminal domain of an archaeal MCM as a right-handed filament.

PubMed

Fu, Yang; Slaymaker, Ian M; Wang, Junfeng; Wang, Ganggang; Chen, Xiaojiang S

2014-04-03

Mini-chromosome maintenance (MCM) proteins are the replicative helicase necessary for DNA replication in both eukarya and archaea. Most of archaea only have one MCM gene. Here, we report a 1.8-Å crystal structure of the N-terminal MCM from the archaeon Thermoplasma acidophilum (tapMCM). In the structure, the MCM N-terminus forms a right-handed filament that contains six subunits in each turn, with a diameter of 25Å of the central channel opening. The inner surface is highly positively charged, indicating DNA binding. This filament structure with six subunits per turn may also suggests a potential role for an open-ring structure for hexameric MCM and dynamic conformational changes in initiation and elongation stages of DNA replication. Copyright © 2014 Elsevier Ltd. All rights reserved.

MCM-BP is required for repression of life-cycle specific genes transcribed by RNA polymerase I in the mammalian infectious form of Trypanosoma brucei.

PubMed

Kim, Hee-Sook; Park, Sung Hee; Günzl, Arthur; Cross, George A M

2013-01-01

Trypanosoma brucei variant surface glycoprotein (VSG) expression is a classic example of allelic exclusion. While the genome of T. brucei contains >2,000 VSG genes and VSG pseudogenes, only one allele is expressed at the surface of each infectious trypanosome and the others are repressed. Along with recombinatorial VSG switching, allelic exclusion provides a major host evasion mechanism for trypanosomes, a phenomenon known as antigenic variation. To extend our understanding of how trypanosomes escape host immunity by differential expression of VSGs, we attempted to identify genes that contribute to VSG silencing, by performing a loss-of-silencing screen in T. brucei using a transposon-mediated random insertional mutagenesis. One identified gene, which we initially named LOS1, encodes a T. brucei MCM-Binding Protein (TbMCM-BP). Here we show that TbMCM-BP is essential for viability of infectious bloodstream-form (BF) trypanosome and is required for proper cell-cycle progression. Tandem affinity purification of TbMCM-BP followed by mass spectrometry identified four subunits (MCM4-MCM7) of the T. brucei MCM complex, a replicative helicase, and MCM8, a subunit that is uniquely co-purified with TbMCM-BP. TbMCM-BP is required not only for repression of subtelomeric VSGs but also for silencing of life-cycle specific, insect-stage genes, procyclin and procyclin-associated genes (PAGs), that are normally repressed in BF trypanosomes and are transcribed by RNA polymerase I. Our study uncovers a functional link between chromosome maintenance and RNA pol I-mediated gene silencing in T. brucei.

Insights into the Initiation of Eukaryotic DNA Replication.

PubMed

Bruck, Irina; Perez-Arnaiz, Patricia; Colbert, Max K; Kaplan, Daniel L

2015-01-01

The initiation of DNA replication is a highly regulated event in eukaryotic cells to ensure that the entire genome is copied once and only once during S phase. The primary target of cellular regulation of eukaryotic DNA replication initiation is the assembly and activation of the replication fork helicase, the 11-subunit assembly that unwinds DNA at a replication fork. The replication fork helicase, called CMG for Cdc45-Mcm2-7, and GINS, assembles in S phase from the constituent Cdc45, Mcm2-7, and GINS proteins. The assembly and activation of the CMG replication fork helicase during S phase is governed by 2 S-phase specific kinases, CDK and DDK. CDK stimulates the interaction between Sld2, Sld3, and Dpb11, 3 initiation factors that are each required for the initiation of DNA replication. DDK, on the other hand, phosphorylates the Mcm2, Mcm4, and Mcm6 subunits of the Mcm2-7 complex. Sld3 recruits Cdc45 to Mcm2-7 in a manner that depends on DDK, and recent work suggests that Sld3 binds directly to Mcm2-7 and also to single-stranded DNA. Furthermore, recent work demonstrates that Sld3 and its human homolog Treslin substantially stimulate DDK phosphorylation of Mcm2. These data suggest that the initiation factor Sld3/Treslin coordinates the assembly and activation of the eukaryotic replication fork helicase by recruiting Cdc45 to Mcm2-7, stimulating DDK phosphorylation of Mcm2, and binding directly to single-stranded DNA as the origin is melted.

Quantitative Proteomics Reveals Dynamic Interactions of the Minichromosome Maintenance Complex (MCM) in the Cellular Response to Etoposide Induced DNA Damage.

PubMed

Drissi, Romain; Dubois, Marie-Line; Douziech, Mélanie; Boisvert, François-Michel

2015-07-01

The minichromosome maintenance complex (MCM) proteins are required for processive DNA replication and are a target of S-phase checkpoints. The eukaryotic MCM complex consists of six proteins (MCM2-7) that form a heterohexameric ring with DNA helicase activity, which is loaded on chromatin to form the pre-replication complex. Upon entry in S phase, the helicase is activated and opens the DNA duplex to recruit DNA polymerases at the replication fork. The MCM complex thus plays a crucial role during DNA replication, but recent work suggests that MCM proteins could also be involved in DNA repair. Here, we employed a combination of stable isotope labeling with amino acids in cell culture (SILAC)-based quantitative proteomics with immunoprecipitation of green fluorescent protein-tagged fusion proteins to identify proteins interacting with the MCM complex, and quantify changes in interactions in response to DNA damage. Interestingly, the MCM complex showed very dynamic changes in interaction with proteins such as Importin7, the histone chaperone ASF1, and the Chromodomain helicase DNA binding protein 3 (CHD3) following DNA damage. These changes in interactions were accompanied by an increase in phosphorylation and ubiquitination on specific sites on the MCM proteins and an increase in the co-localization of the MCM complex with γ-H2AX, confirming the recruitment of these proteins to sites of DNA damage. In summary, our data indicate that the MCM proteins is involved in chromatin remodeling in response to DNA damage. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Preparation of H3PW12O40/MCM-48 and its photocatalytic degradation of pesticides.

PubMed

Liu, Xia; Li, Yan-zhou; Gan, Qiang; Feng, Chang-gen

2014-08-01

A composite catalyst H3PW12O40/MCM-48 was prepared by loading photocatalyst phosphotungstic acid H3PW12O40 (HPW) to molecular sieve MCM-48 by impregnation method, and its structure was characterized by Fourier transform infrared (FT-IR) spectra, small angle X-ray diffraction (XRD) patterns, nitrogen adsorption analysis and High-resolution transmission electron microscopy (HRTEM) analysis. Photocatalytic degradation activities of HPW/MCM-48 against pesticides imidacloprid and paraquat were evaluated under UV radiation (365 nm). The results show that HPW/MCM-48 maintains the mesoprous molecular sieve structure of MCM-48 and the Keggin structure of HPW, while the BET surface area is 793.35 m2 x g(-1), pore volume is 1.46 cm3 x g(-1), average pore diameter is 2.76 nm, suggesting loading HPW on MCM-48 is a considerable way to improve its surface area. After 14 h UV irradiation (365 nm), 57.38% imidacloprid and 63.79% paraquat were degraded by 20 mg HPW/MCM-48 catalyst, while HPW and blank group degraded the two pesticides at the degradation rate of about 25% and 5%, respectively. Implying loading on MCM-48 could greaterly improve the degradation activity of HPW. The reslut of degradation kinetics show that, the degradation process of HPW/MCM-48 fits first order kinetics equation. The rate constant Ka of HPW/MCM-48 toward imidacloprid and paraquat are 0.089 h and 0.117 h, with the half-life t(1/2) of 7.8 h and 5.9 h, respectively.

LSST camera control system

NASA Astrophysics Data System (ADS)

Marshall, Stuart; Thaler, Jon; Schalk, Terry; Huffer, Michael

2006-06-01

The LSST Camera Control System (CCS) will manage the activities of the various camera subsystems and coordinate those activities with the LSST Observatory Control System (OCS). The CCS comprises a set of modules (nominally implemented in software) which are each responsible for managing one camera subsystem. Generally, a control module will be a long lived "server" process running on an embedded computer in the subsystem. Multiple control modules may run on a single computer or a module may be implemented in "firmware" on a subsystem. In any case control modules must exchange messages and status data with a master control module (MCM). The main features of this approach are: (1) control is distributed to the local subsystem level; (2) the systems follow a "Master/Slave" strategy; (3) coordination will be achieved by the exchange of messages through the interfaces between the CCS and its subsystems. The interface between the camera data acquisition system and its downstream clients is also presented.

Archaeal orthologs of Cdc45 and GINS form a stable complex that stimulates the helicase activity of MCM

PubMed Central

Xu, Yuli; Gristwood, Tamzin; Hodgson, Ben; Trinidad, Jonathan C.; Albers, Sonja-Verena; Bell, Stephen D.

2016-01-01

The regulated recruitment of Cdc45 and GINS is key to activating the eukaryotic MCM(2-7) replicative helicase. We demonstrate that the homohexameric archaeal MCM helicase associates with orthologs of GINS and Cdc45 in vivo and in vitro. Association of these factors with MCM robustly stimulates the MCM helicase activity. In contrast to the situation in eukaryotes, archaeal Cdc45 and GINS form an extremely stable complex before binding MCM. Further, the archaeal GINS•Cdc45 complex contains two copies of Cdc45. Our analyses give insight into the function and evolution of the conserved core of the archaeal/eukaryotic replisome. PMID:27821767

Archaeal orthologs of Cdc45 and GINS form a stable complex that stimulates the helicase activity of MCM.

PubMed

Xu, Yuli; Gristwood, Tamzin; Hodgson, Ben; Trinidad, Jonathan C; Albers, Sonja-Verena; Bell, Stephen D

2016-11-22

The regulated recruitment of Cdc45 and GINS is key to activating the eukaryotic MCM(2-7) replicative helicase. We demonstrate that the homohexameric archaeal MCM helicase associates with orthologs of GINS and Cdc45 in vivo and in vitro. Association of these factors with MCM robustly stimulates the MCM helicase activity. In contrast to the situation in eukaryotes, archaeal Cdc45 and GINS form an extremely stable complex before binding MCM. Further, the archaeal GINS•Cdc45 complex contains two copies of Cdc45. Our analyses give insight into the function and evolution of the conserved core of the archaeal/eukaryotic replisome.

Spherical V-Fe-MCM-48: The Synthesis, Characterization and Hydrothermal Stability.

PubMed

Qian, Wang; Wang, Haiqing; Chen, Jin; Kong, Yan

2015-04-14

Spherical MCM-48 mesoporous sieve co-doped with vanadium and iron was successfully synthesized via one-step hydrothermal method. The material was characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption isotherms, inductively coupled plasma (ICP), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance UV-vis spectra, and X-ray photoelectron spectra (XPS) techniques. Results indicated that the V-Fe-MCM-48 showed an ordered 3D cubic mesostructure with spherical morphology, narrow pore size distribution and high specific surface area. Most of vanadium and iron atoms existing as tetrahedral V 4+ and Fe 3+ species were co-doped into the silicate framework. The particle sizes of V-Fe-MCM-48 were smaller and the specific area was much higher than those of of V-MCM-48. Additionally, the synthesized V-Fe-MCM-48 exhibited improved hydrothermal stability compared with the pure MCM-48.

Hydroisomerization of n-dodecane over Pt/Al-MCM-48 catalysts.

PubMed

Yun, Soyoung; Park, Young-Kwon; Jeong, Soon-Yong; Han, Jeongsik; Jeon, Jong-Ki

2014-04-01

The objective of this study is to evaluate the catalytic potential of Pt/Al-MCM-48 catalysts in hydroisomerization of n-dodecane. The effects of the Si/Al ratio and platinum loading on the acid characteristics of Al-MCM-48 and the catalytic performance in n-dodecane hydroisomerization were analyzed. The catalysts were characterized by X-ray diffraction, nitrogen adsorption, infrared spectroscopy of pyridine adsorption, and temperature programmed desorption of ammonia. The number of weak strength acid sites on Al-MCM-48 increased with 0.5 wt% platinum loading. The weak strength acid sites of Pt/Al-MCM-48 catalysts were ascribed to Lewis acid sites, which can be confirmed by NH3-TPD and FTIR spectra of pyridine adsorption. Iso-dodecane can be produced with high selectivity in n-dodecane hydrosisomerization over Pt/Al-MCM-48 catalysts. This is attributed to the mild acidic properties of Pt/Al-MCM-48 catalysts.

Spherical V-Fe-MCM-48: The Synthesis, Characterization and Hydrothermal Stability

PubMed Central

Qian, Wang; Wang, Haiqing; Chen, Jin; Kong, Yan

2015-01-01

Spherical MCM-48 mesoporous sieve co-doped with vanadium and iron was successfully synthesized via one-step hydrothermal method. The material was characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption isotherms, inductively coupled plasma (ICP), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance UV-vis spectra, and X-ray photoelectron spectra (XPS) techniques. Results indicated that the V-Fe-MCM-48 showed an ordered 3D cubic mesostructure with spherical morphology, narrow pore size distribution and high specific surface area. Most of vanadium and iron atoms existing as tetrahedral V4+ and Fe3+ species were co-doped into the silicate framework. The particle sizes of V-Fe-MCM-48 were smaller and the specific area was much higher than those of of V-MCM-48. Additionally, the synthesized V-Fe-MCM-48 exhibited improved hydrothermal stability compared with the pure MCM-48. PMID:28788030

Grafting of a novel gold(III) complex on nanoporous MCM-41 and evaluation of its toxicity in Saccharomyces cerevisiae.

PubMed

Fazaeli, Yousef; Amini, Mostafa M; Ashourion, Hamed; Heydari, Homayoun; Majdabadi, Abbas; Jalilian, Amir Reza; Abolmaali, Shamsozoha

2011-01-01

The goal of this research was to investigate the potential of newly synthesized gold complex trichloro(2,4,6-trimethylpyridine)Au(III) as an anticancer agent. The gold(III) complex was synthesized and grafted on nanoporous silica, MCM-41, to produce AuCl(3)@PF-MCM- 41 (AuCl(3) grafted on pyridine-functionalized MCM-41). The toxicity of trichloro(2,4,6- trimethylpyridine)Au(III) and AuCl(3)@PF-MCM-41 in Saccharomyces cerevisiae (as a model system) was studied. The gold(III) complex showed a mid cytotoxic effect on yeast viability. Using the drug delivery system, nanoporous MCM-41, the gold(III) complex became a strong inhibitor for growth of yeast cells at a very low concentration. Furthermore, the animal tests revealed a high uptake of AuCl(3)@PF-MCM-41 in tumor cells. The stability of the compound was confirmed in human serum.

Preparation of H-mordenite/MCM-48 composite and its catalytic performance in the alkylation of toluene with tert-butanol

NASA Astrophysics Data System (ADS)

Zhou, Zhiwei; Cheng, Fuling; Qin, Juan; Yu, Pengcheng; Xu, Lin; Gu, Zhiqiang; Liu, Xiaoqin; Wu, Wenliang

2017-09-01

A series of HM/MCM-48 samples with different SiO2/Al2O3 molar ratio were prepared by sol-gel method. The prepared catalysts were characterized by XRD, N2 adsorption-desorption, NH3-TPD, FT-IR, SEM, and TEM techniques, and their catalytic performance was investigated in alkylation of toluene with tert-butanol. The adsorption capacity and the acid sites amount of HM/MCM-48-4 sample prepared by growing MCM-48 on the surface of HM zeolite are much higher than that of their mechanical mixture (HM/MCM-48(4) sample) due to its biporous structure; it shows higher catalytic performance than other HM/MCM-48 samples. The influence of reaction conditions on the catalytic performance of HM/MCM-48-4 zeolite was discussed. Toluene conversion of 41.4% and p-tert-butyltoluene selectivity of 73.5% were obtained at the weight ratio of toluene to HM/MCM-48-4 of 5, reaction temperature of 453 K, reaction time of 5 h and the molar ratio of toluene to tert-butanol of 0.5.

Dry soldering with hot filament produced atomic hydrogen

DOEpatents

Panitz, J.K.G.; Jellison, J.L.; Staley, D.J.

1995-04-25

A system is disclosed for chemically transforming metal surface oxides to metal that is especially, but not exclusively, suitable for preparing metal surfaces for dry soldering and solder reflow processes. The system employs one or more hot, refractory metal filaments, grids or surfaces to thermally dissociate molecular species in a low pressure of working gas such as a hydrogen-containing gas to produce reactive species in a reactive plasma that can chemically reduce metal oxides and form volatile compounds that are removed in the working gas flow. Dry soldering and solder reflow processes are especially applicable to the manufacture of printed circuit boards, semiconductor chip lead attachment and packaging multichip modules. The system can be retrofitted onto existing metal treatment ovens, furnaces, welding systems and wave soldering system designs. 1 fig.

Powerful, Efficient Electric Vehicle Chargers: Low-Cost, Highly-Integrated Silicon Carbide (SiC) Multichip Power Modules (MCPMs) for Plug-In Hybrid Electric

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2010-09-14

ADEPT Project: Currently, charging the battery of an electric vehicle (EV) is a time-consuming process because chargers can only draw about as much power from the grid as a hair dryer. APEI is developing an EV charger that can draw as much power as a clothes dryer, which would drastically speed up charging time. APEI's charger uses silicon carbide (SiC)-based power transistors. These transistors control the electrical energy flowing through the charger's circuits more effectively and efficiently than traditional transistors made of straight silicon. The SiC-based transistors also require less cooling, enabling APEI to create EV chargers that are 10more » times smaller than existing chargers.« less

The expression of MCM-2 in invasive breast carcinoma: a stereologic approach.

PubMed

Cobanoglu, Umit; Mungan, Sevdegul; Gundogdu, Cemal; Ersoz, Safak; Ozoran, Yavuz; Aydin, Fazil

2010-01-01

The aim of this study is to examine the expression of MCM-2 and conventional proliferation marker Ki-67 in breast carcinoma by stereologic technique and to compare it with various clinicopathologic parameters. The expression of MCM-2 and Ki-67 on paraffin-embedded tumor tissue sections of patients with invasive breast carcinoma was analyzed immunohistochemically. Stereologic method was used for evaluation of the percentage of positively stained tumor cells. Significant positive correlation was found between the expression of MCM-2 and that of Ki-67 (r = 0.74, p < 0.001). MCM-2 and Ki-67 expression was significantly associated with histologic grade (p < 0.05), and negative correlation was observed between MCM-2 or Ki-67 expression and estrogen status (p < 0.05). No significant association was observed between MCM-2 or Ki-67 expression and patient age, tumor size, lymph node status, clinical stage and menopausal status. Our results suggest that MCM-2 expression is significantly associated with histologic grade of breast carcinoma and with cell proliferation capacity (Ki-67 labelling index). Additional studies are required using the stereologic method to compare and understand the utility of Ki-67 and MCM-2 expression in invasive breast carcinoma (Tab. 1, Fig. 4, Ref. 34). Full Text (Free, PDF) www.bmj.sk.

Paraquat adsorption on NaX and Al-MCM-41.

PubMed

Rongchapo, Wina; Deekamwong, Krittanun; Loiha, Sirinuch; Prayoonpokarach, Sanchai; Wittayakun, Jatuporn

2015-01-01

The aim of this work is to determine paraquat adsorption capacity of zeolite NaX and Al-MCM-41. All adsorbents were synthesized by hydrothermal method using rice husk silica. For Al-MCM-41, aluminum (Al) was added to the synthesis gel of MCM-41 with Al content of 10, 15, 20 and 25 wt%. The faujasite framework type of NaX and mesoporous characteristic of Al-MCM-41 were confirmed by X-ray diffraction. Surface area of all adsorbents determined by N2 adsorption-desorption analysis was higher than 650 m2/g. Al content and geometry were determined by X-ray fluorescence and 27Al nuclear magnetic resonance, respectively. Morphology of Al-MCM-41 were studied by transmission electron microscopy; macropores and defects were observed. The paraquat adsorption experiments were conducted using a concentration range of 80-720 mg/L for NaX and 80-560 mg/L for Al-MCM-41. The paraquat adsorption isotherms from all adsorbents fit well with the Langmuir model. The adsorption capacity of NaX was 120 mg/g-adsorbent. Regarding Al-MCM-41, the 10% Al-MCM-41 exhibited the lowest capacity of 52 mg/g-adsorbent while the other samples had adsorption capacity of 66 mg/g-adsorbent.

Application of Mn/MCM-41 as an adsorbent to remove methyl blue from aqueous solution.

PubMed

Shao, Yimin; Wang, Xi; Kang, Yuan; Shu, Yuehong; Sun, Qiangqiang; Li, Laisheng

2014-09-01

In this study, the application of Mn loaded MCM-41 (Mn/MCM-41) was reported as a novel adsorbent for methyl blue (MB) from aqueous solution. The mesoporous structure of Mn/MCM-41 was confirmed by XRD technique. Surface area, pore size and wall thickness were calculated from BET equation and BJH method using nitrogen sorption technique. FT-IR studies showed that Mn were loaded on the hexagonal mesoporous structures of MCM-41. It is found that the MCM-41 structure retained after loading of Mn but its surface area and pore diameter decreased due to pore blockage. Adsorption of MB from aqueous solution was investigated by Mn/MCM-41 with changing Mn content, adsorbent dosage, initial MB concentration, contact time, pH and the temperature. Under the chosen condition (25°C, 0.02 g adsorbent dosage, 6.32 pH, 50 mg L(-1) MB, 1 wt.% Mn), a high MB adsorption capacity (45.38 mg g(-1)) was achieved by Mn/MCM-41 process at 120 min, 8.6 times higher than MCM-41. The electrostatic interaction was considered to be the main mechanism for the dye adsorption. The experimental data fitted well to Freundlich and Dubinin-Radushkevich isotherms. The adsorption of MB on Mn/MCM-41 followed pseudo-second-order kinetics. Thermodynamic parameters suggested that the adsorption process is endothermic and spontaneous. Copyright © 2014 Elsevier Inc. All rights reserved.

The Fertilization-Induced DNA Replication Factor MCM6 of Maize Shuttles between Cytoplasm and Nucleus, and Is Essential for Plant Growth and Development1

PubMed Central

Dresselhaus, Thomas; Srilunchang, Kanok-orn; Leljak-Levanić, Dunja; Schreiber, Daniela N.; Garg, Preeti

2006-01-01

The eukaryotic genome is duplicated exactly once per cell division cycle. A strategy that limits every replication origin to a single initiation event is tightly regulated by a multiprotein complex, which involves at least 20 protein factors. A key player in this regulation is the evolutionary conserved hexameric MCM2-7 complex. From maize (Zea mays) zygotes, we have cloned MCM6 and characterized this essential gene in more detail. Shortly after fertilization, expression of ZmMCM6 is strongly induced. During progression of zygote and proembryo development, ZmMCM6 transcript amounts decrease and are low in vegetative tissues, where expression is restricted to tissues containing proliferating cells. The highest protein amounts are detectable about 6 to 20 d after fertilization in developing kernels. Subcellular localization studies revealed that MCM6 protein shuttles between cytoplasm and nucleoplasm in a cell cycle-dependent manner. ZmMCM6 is taken up by the nucleus during G1 phase and the highest protein levels were observed during late G1/S phase. ZmMCM6 is excluded from the nucleus during late S, G2, and mitosis. Transgenic maize was generated to overexpress and down-regulate ZmMCM6. Plants displaying minor antisense transcript amounts were reduced in size and did not develop cobs to maturity. Down-regulation of ZmMCM6 gene activity seems also to affect pollen development because antisense transgenes could not be propagated via pollen to wild-type plants. In summary, the transgenic data indicate that MCM6 is essential for both vegetative as well as reproductive growth and development in plants. PMID:16407440

The fertilization-induced DNA replication factor MCM6 of maize shuttles between cytoplasm and nucleus, and is essential for plant growth and development.

PubMed

Dresselhaus, Thomas; Srilunchang, Kanok-Orn; Leljak-Levanic, Dunja; Schreiber, Daniela N; Garg, Preeti

2006-02-01

The eukaryotic genome is duplicated exactly once per cell division cycle. A strategy that limits every replication origin to a single initiation event is tightly regulated by a multiprotein complex, which involves at least 20 protein factors. A key player in this regulation is the evolutionary conserved hexameric MCM2-7 complex. From maize (Zea mays) zygotes, we have cloned MCM6 and characterized this essential gene in more detail. Shortly after fertilization, expression of ZmMCM6 is strongly induced. During progression of zygote and proembryo development, ZmMCM6 transcript amounts decrease and are low in vegetative tissues, where expression is restricted to tissues containing proliferating cells. The highest protein amounts are detectable about 6 to 20 d after fertilization in developing kernels. Subcellular localization studies revealed that MCM6 protein shuttles between cytoplasm and nucleoplasm in a cell cycle-dependent manner. ZmMCM6 is taken up by the nucleus during G1 phase and the highest protein levels were observed during late G1/S phase. ZmMCM6 is excluded from the nucleus during late S, G2, and mitosis. Transgenic maize was generated to overexpress and down-regulate ZmMCM6. Plants displaying minor antisense transcript amounts were reduced in size and did not develop cobs to maturity. Down-regulation of ZmMCM6 gene activity seems also to affect pollen development because antisense transgenes could not be propagated via pollen to wild-type plants. In summary, the transgenic data indicate that MCM6 is essential for both vegetative as well as reproductive growth and development in plants.

Preparation and characterization of polyaniline-containing Na-AlMCM-41 as composite material with semiconductor behavior.

PubMed

Anunziata, Oscar A; Gómez Costa, Marcos B; Sánchez, Rodolfo D

2005-12-15

Composite material formed from a mesoporous aluminosilicate, Na-AlMCM-41, with conducting polyaniline (PANI) has been synthesized by an in situ polymerization technique. Studies of aniline adsorption over mesoporous Na-AlMCM-41 synthesized in our laboratory allowed us to find the modes in which aniline interacts with the active sites of Na-AlMCM-41. In order to obtain the best reaction conditions to polymerize aniline onto Na-AlMCM-41, aniline was first polymerized to produce pure PANI. Hence, the oxidative in situ polymerization was carried out by two procedures, differing in the polymerization time and in static or stirring conditions. Studies of infrared spectroscopy and UV-vis spectroscopy indicated that higher polymerization time and static conditions allowed us to obtain mainly polyaniline in emeraldine form on the host. The N(2) isotherm of the polyaniline/Na-AlMCM-41 composite (PANI/MCM) indicated that the shape was similar to that of MCM, but the shift to saturation transition to lower partial pressure shows that the channels are occupied by PANI and they are now narrowed. The thermal properties of PANI, Na-AlMCM-41, and composite were investigated by TGA analyses and we found that the polymer shows higher thermal stability when it is forming the composite. Scanning electron microscopy indicated that PANI is not on the outer surface of the host. Conductivity studies show that PANI/Na-AlMCM-41 exhibits semiconductor behavior at room temperature and its conductivity was 7.0 x 10(-5) S/cm, smaller than that of pure polyaniline. PANI/Na-AlMCM-41 conductivity shows an increase as temperature increases. Magnetic measurements at room temperature confirmed that the composite has paramagnetic behavior; at lower temperatures the composite became diamagnetic.

Hydroconversion of methyl laurate on bifunctional Ni2P/AlMCM-41 catalyst prepared via in situ phosphorization using triphenylphosphine

NASA Astrophysics Data System (ADS)

Zhao, Sha; Zhang, Zhena; Zhu, Kongying; Chen, Jixiang

2017-05-01

A series of Ni2P/AlMCM-41-x bifunctional catalysts with different Si/Al ratios (x) were synthesized by in situ phosphorization of Ni/AlMCM-41-x with triphenylphosphine (nominal Ni/P ratio of 0.75) at 300 °C on a fixed-bed reactor. For comparison, NiP/AlMCM-41-5-TPR was also prepared by the TPR method from the supported nickel phosphate with the Ni/P ratio of 1.0, during which metallic Ni rather than Ni2P formed. TEM images show that Ni and Ni2P particles uniformly distributed in Ni2P/AlMCM-41-x and NiP/AlMCM-41-5-TPR. The Ni2P/AlMCM-41-x acidity increased with decreasing the Si/Al ratio. In the hydroconversion of methyl laurate, the conversions were close to 100% on all catalysts at 360 °C, 3.0 MPa, methyl laurate WHSV of 2 h-1 and H2/methyl laurate ratio of 25. As to Ni2P/AlMCM-41-x, with decreasing the Si/Al ratio, the total selectivity to C11 and C12 hydrocarbons decreased, while the total selectivity to isoundecane and isododecane (Si-C11+i-C12) firstly increased and then decreased. Ni2P/AlMCM-41-5 gave the largest Si-C11+i-C12 of 43.2%. While NiP/AlMCM-41-5-TPR gave higher Si-C11+i-C12 than Ni2P/AlMCM-41-5, it was more active for the undesired Csbnd C bond cleavage and methanation. We propose that the in-situ phosphorization adopted here is a promising approach to preparing Ni2P-based bifunctional catalysts.

MCM-BP Is Required for Repression of Life-Cycle Specific Genes Transcribed by RNA Polymerase I in the Mammalian Infectious Form of Trypanosoma brucei

PubMed Central

Kim, Hee-Sook; Park, Sung Hee; Günzl, Arthur; Cross, George A. M.

2013-01-01

Trypanosoma brucei variant surface glycoprotein (VSG) expression is a classic example of allelic exclusion. While the genome of T. brucei contains >2,000 VSG genes and VSG pseudogenes, only one allele is expressed at the surface of each infectious trypanosome and the others are repressed. Along with recombinatorial VSG switching, allelic exclusion provides a major host evasion mechanism for trypanosomes, a phenomenon known as antigenic variation. To extend our understanding of how trypanosomes escape host immunity by differential expression of VSGs, we attempted to identify genes that contribute to VSG silencing, by performing a loss-of-silencing screen in T. brucei using a transposon-mediated random insertional mutagenesis. One identified gene, which we initially named LOS1, encodes a T. brucei MCM-Binding Protein (TbMCM-BP). Here we show that TbMCM-BP is essential for viability of infectious bloodstream-form (BF) trypanosome and is required for proper cell-cycle progression. Tandem affinity purification of TbMCM-BP followed by mass spectrometry identified four subunits (MCM4-MCM7) of the T. brucei MCM complex, a replicative helicase, and MCM8, a subunit that is uniquely co-purified with TbMCM-BP. TbMCM-BP is required not only for repression of subtelomeric VSGs but also for silencing of life-cycle specific, insect-stage genes, procyclin and procyclin-associated genes (PAGs), that are normally repressed in BF trypanosomes and are transcribed by RNA polymerase I. Our study uncovers a functional link between chromosome maintenance and RNA pol I-mediated gene silencing in T. brucei. PMID:23451133

Cryo-EM structure of Mcm2-7 double hexamer on DNA suggests a lagging-strand DNA extrusion model.

PubMed

Noguchi, Yasunori; Yuan, Zuanning; Bai, Lin; Schneider, Sarah; Zhao, Gongpu; Stillman, Bruce; Speck, Christian; Li, Huilin

2017-11-07

During replication initiation, the core component of the helicase-the Mcm2-7 hexamer-is loaded on origin DNA as a double hexamer (DH). The two ring-shaped hexamers are staggered, leading to a kinked axial channel. How the origin DNA interacts with the axial channel is not understood, but the interaction could provide key insights into Mcm2-7 function and regulation. Here, we report the cryo-EM structure of the Mcm2-7 DH on dsDNA and show that the DNA is zigzagged inside the central channel. Several of the Mcm subunit DNA-binding loops, such as the oligosaccharide-oligonucleotide loops, helix 2 insertion loops, and presensor 1 (PS1) loops, are well defined, and many of them interact extensively with the DNA. The PS1 loops of Mcm 3, 4, 6, and 7, but not 2 and 5, engage the lagging strand with an approximate step size of one base per subunit. Staggered coupling of the two opposing hexamers positions the DNA right in front of the two Mcm2-Mcm5 gates, with each strand being pressed against one gate. The architecture suggests that lagging-strand extrusion initiates in the middle of the DH that is composed of the zinc finger domains of both hexamers. To convert the Mcm2-7 DH structure into the Mcm2-7 hexamer structure found in the active helicase, the N-tier ring of the Mcm2-7 hexamer in the DH-dsDNA needs to tilt and shift laterally. We suggest that these N-tier ring movements cause the DNA strand separation and lagging-strand extrusion. Copyright © 2017 the Author(s). Published by PNAS.

Structural and mechanistic insights into Mcm2-7 double-hexamer assembly and function

DOE PAGES

Sun, Jingchuan; Li, Huilin; Fernandez-Cid, Alejandra; ...

2014-10-15

Eukaryotic cells license each DNA replication origin during G1 phase by assembling a prereplication complex that contains a Mcm2–7 (minichromosome maintenance proteins 2–7) double hexamer. During S phase, each Mcm2–7 hexamer forms the core of a replicative DNA helicase. However, the mechanisms of origin licensing and helicase activation are poorly understood. The helicase loaders ORC–Cdc6 function to recruit a single Cdt1–Mcm2–7 heptamer to replication origins prior to Cdt1 release and ORC–Cdc6–Mcm2–7 complex formation, but how the second Mcm2–7 hexamer is recruited to promote double-hexamer formation is not well understood. Here, structural evidence for intermediates consisting of an ORC–Cdc6–Mcm2–7 complex andmore » an ORC–Cdc6–Mcm2–7–Mcm2–7 complex are reported, which together provide new insights into DNA licensing. Detailed structural analysis of the loaded Mcm2–7 double-hexamer complex demonstrates that the two hexamers are interlocked and misaligned along the DNA axis and lack ATP hydrolysis activity that is essential for DNA helicase activity. Moreover, we show that the head-to-head juxtaposition of the Mcm2–7 double hexamer generates a new protein interaction surface that creates a multisubunit-binding site for an S-phase protein kinase that is known to activate DNA replication. The data suggest how the double hexamer is assembled and how helicase activity is regulated during DNA licensing, with implications for cell cycle control of DNA replication and genome stability.« less

Rare earth (Eu{sup 3+}, Tb{sup 3+}) mesoporous hybrids with calix[4]arene derivative covalently linking MCM-41: Physical characterization and photoluminescence property

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li Yajuan; Yan Bing, E-mail: byan@tongji.edu.cn; Wang Li

2011-09-15

MCM-41 mesoporous silica has been functionalized with two kinds of macrocylic calixarene derivatives Calix[4] and Calix[4]Br (Calix[4]=P-tert-butylcalix[4]arene, Calix[4]Br=5.11,17.23-tetra-tert-butyl-25.27-bihydroxy- 26.28-bibromopropoxycalix[4]arene) through condensation approach of tetraethoxysilane (TEOS) in the presence of the cetyltrimethylammonium bromide (CTAB) surfactant as a template. Novel organic-inorganic mesoporous luminescent hybrid containing RE{sup 3+} (Eu{sup 3+}, Tb{sup 3+}) complexes covalently attached to the functionalized ordered mesoporous MCM-41, which are designated as RE-Calix[4]-MCM-41 and RE-Calix[4]Br-MCM-41, respectively, are obtained by sol-gel process. It is found that they all have high surface area, uniform in the mesostructure and good crystallinity. Measurement of the photoluminescence properties show the mesoporous material covalently bonded Tb{supmore » 3+} complexes (Tb-Calix[4]-MCM-41 and Tb-Calix[4]Br-MCM-41) exhibit the stronger characteristic emission of Tb{sup 3+} and longer lifetime than the corresponding Eu-containing materials Eu-Calix[4]-MCM-41 and Eu-Calix[4]Br-MCM-41 due to the triplet state energy of modified organic ligands Calix[4]-Si and Calix[4]Br-Si match with the emissive energy level of Tb{sup 3+} very well. - Graphical abstract: MCM-41 mesoporous silica is functionalized with two kinds of macrocylic calixarene derivatives and luminescent organic-inorganic mesoporous hybrids containing Ln{sup 3+} complexes covalently attached to the functionalized ordered mesoporous MCM-41. Highlights: > Novel linkages of functionalized calixarene derivative. > New rare earth mesoporous hybrids. > Luminescence in visible region.« less

Structure and photocatalytic activity studies of TiO{sub 2}-supported over Ce-modified Al-MCM-41

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krishna Reddy, Jakkidi; Durgakumari, Valluri, E-mail: durgakumari@iict.res.in; Subrahmanyam, Machiraju

2009-07-01

Ce-Al-MCM-41, TiO{sub 2}/Al-MCM-41 and TiO{sub 2}/Ce-Al-MCM-41 materials with varying contents of Ce (by impregnation) and TiO{sub 2} loaded (by solid-state dispersion) on Al-MCM-41 support are prepared. The Ce modified and TiO{sub 2} loaded composite systems are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectra (DRS) and X-ray photoelectron spectroscopy (XPS) techniques. The DRS and XPS of low Ce content (0.2-0.5 wt.%) modified Al-MCM-41 samples are showing more characteristic of Ce{sup 3+} species wherein cerium in interaction with Al-MCM-41 and that of high Ce (0.8, 3.0 wt.%) content modified samples are showing the characteristic of bothmore » Ce{sup 4+}and Ce{sup 3+}species. A series of Ce-modified Al-MCM-41 and TiO{sub 2} loaded composite catalysts are evaluated for photocatalytic degradation of phenol under UV irradiation. Low Ce content in Ce{sup 3+} state on Al-MCM-41 is showing good photoactivity in comparison with high Ce content samples and pure ceria. The composite TiO{sub 2}/Ce-Al-MCM-41 is showing enhanced degradation activity due decreased rate of electron-hole recombination on TiO{sub 2} surface by the redox properties of cerium. The photocatalyst TiO{sub 2}/Ce-Al-MCM-41 with an optimum of 10 wt.% TiO{sub 2} and 0.3 wt.% Ce is showing maximum phenol degradation activity. The possible mechanism of phenol degradation on the composite photocatalyst is proposed.« less

Replication protein A in nonearly ovarian adenocarcinomas: correlation with MCM-2, MCM-5, Ki-67 index and prognostic significance.

PubMed

Levidou, Georgia; Ventouri, Kiriaki; Nonni, Afroditi; Gakiopoulou, Hariklia; Bamias, Aristotle; Sotiropoulou, Maria; Papaspirou, Irene; Dimopoulos, Meletios A; Patsouris, Efstratios; Korkolopoulou, Penelope

2012-07-01

Replication protein A (RPA) is an ssDNA-binding protein required for the initiation of DNA replication and the stabilization of ssDNA. Collaboration with several molecules, that is, the MCM2-7 complex, has been suggested to be imperative for its multifaceted role. In this study, we investigated the immunohistochemical expression of the RPA2 subunit in correlation with the MCM-2 and MCM-5 and Ki67 index, and assessed its prognostic significance in 76 patients with nonearly ovarian adenocarcinomas, the majority of whom had a serous histotype. RPA2 protein expression was observed in all cases, whereas the staining intensity varied from weak to strong. RPA2 expression was correlated with the tumor stage in the entire cohort and in serous tumors (P=0.0053 in both relationships). Moreover, RPA2 immunoexpression was positively correlated with MCM-2 (P=0.0001) and MCM-5 (P<0.0001) expression, but was unrelated to the Ki67 index (P>0.10). In multivariate survival analysis, RPA2 expression emerged as an independent predictor of adverse outcome (P<0.0001) along with tumor histologic grade. RPA2 remained an independent predictor of survival (P=0.002) even after adjustment for MCM-2 and MCM-5 expression and when analysis was restricted to serous carcinomas (P=0.004). Our results further support the interrelation of RPA2 protein with MCM-2 and MCM-5 in OCs. Moreover, RPA2 protein may play an important role in ovarian tumorigenesis, and may serve as a useful independent molecular marker for stratifying patients with OC in terms of prognosis.

High-performance packaging for monolithic microwave and millimeter-wave integrated circuits

NASA Technical Reports Server (NTRS)

Shalkhauser, K. A.; Li, K.; Shih, Y. C.

1992-01-01

Packaging schemes were developed that provide low-loss, hermetic enclosure for advanced monolithic microwave and millimeter-wave integrated circuits (MMICs). The package designs are based on a fused quartz substrate material that offers improved radio frequency (RF) performance through 44 gigahertz (GHz). The small size and weight of the packages make them appropriate for a variety of applications, including phased array antenna systems. Packages were designed in two forms; one for housing a single MMIC chip, the second in the form of a multi-chip phased array module. The single chip array module was developed in three separate sizes, for chips of different geometry and frequency requirements. The phased array module was developed to address packaging directly for antenna applications, and includes transmission line and interconnect structures to support multi-element operation. All packages are fabricated using fused quartz substrate materials. As part of the packaging effort, a test fixture was developed to interface the single chip packages to conventional laboratory instrumentation for characterization of the packaged devices. The package and test fixture designs were both developed in a generic sense, optimizing performance for a wide range of possible applications and devices.

Characterization and clinical validation of MCM2 and TOP2A monoclonal antibodies in the BD ProEx™ C assay: An immunoassay which detects aberrant S-phase induction in cervical tissue.

PubMed

Dixon, Eric P; King, Lorraine M; Nelson, Ramona; Simkins, Stephen G; Knapp, Steven L; Brough, George H; Lenz, Karen L; Henderson, Dorian T; Whitehead, Clark M; Hessling, Janice; Brown, Charlotte A; Malinowski, Douglas P

2017-03-01

The Papanicolaou (Pap) screen has been successful in reducing cervical cancer; but exhibits low sensitivity when detecting cervical dysplasia. Use of molecular biomarkers in Pap tests may improve diagnostic accuracy. Monoclonal antibodies to Minichromosome Maintenance Protein 2 (MCM2) and DNA Topoisomerase II α (TOP2A) were selected for use in IHC based on their ability to differentiate normal from diseased cervical tissues in tissue microarrays. Enhanced Green Fluorescent Protein Western blot analysis was used to help identify binding epitopes specific to MCM2 and TOP2A antibody clones. Antibody affinity was determined by solution phase affinity measurement and immunohistochemistry was performed using high affinity MCM2 or TOP2A antibodies on serial histological sections. Antibody clones to MCM2 and TOP2A clones were selected based on their ability to detect over expression in abnormal cervical epithelia. In IHC, MCM2-27C5.6 and MCM2-26H6.19 demonstrated superior staining in abnormal cervical tissue over the MCM2-CRCT2.1 antibody. A combination of MCM2 and TOP2A antibodies showed greater staining when compared to staining with any of the antibodies alone on serial histological sections. Distinct linear epitopes were elucidated for each of the MCM2 and TOP2A clones. Affinity values (Kd) for MCM2 or TOP2A antibodies had a similar range. In a research study, the MCM2 and TOP2A (BD ProEx™ C) antibody cocktail showed increased epithelia staining with increasing dysplasia. The use of BD ProEx™ C in combination with H&E staining enhanced immunohistochemical discrimination of dysplastic and non-dysplastic FFPE cervical tissue specimens. BD ProEx™ C containing MCM2 and TOP2A antibodies showed strong specific nuclear staining that correlated with increased dysplasia and lesion severity. Enhanced performance of the antibodies was linked to their unique topography recognition. BD ProEx™ C incorporates antibodies that enhance detection of CIN2+ cervical disease. Copyright © 2017 Elsevier B.V. All rights reserved.

78 FR 36017 - MCM Rail Services LLC, d/b/a Baltimore Industrial Railroad-Operation Exemption-Hilco SP Rail, LLC

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-14

... DEPARTMENT OF TRANSPORTATION Surface Transportation Board [Docket No. FD 35725] MCM Rail Services LLC, d/b/a Baltimore Industrial Railroad-- Operation Exemption--Hilco SP Rail, LLC MCM Rail Services LLC, d/b/a Baltimore Industrial Railroad (MCM), a noncarrier, has filed a verified notice of exemption...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meagher, Martin; Enemark, Eric J.

The crystal structure of the N-terminal domain of thePyrococcus furiosusminichromosome maintenance (MCM) protein as a double hexamer is described. The MCM complex is a ring-shaped helicase that unwinds DNA at the replication fork of eukaryotes and archaea. Prior to replication initiation, the MCM complex assembles as an inactive double hexamer at specific sites of DNA. The presented structure is highly consistent with previous MCM double-hexamer structures and shows two MCM hexamers with a head-to-head interaction mediated by the N-terminal domain. Minor differences include a diminished head-to-head interaction and a slightly reduced inter-hexamer rotation.

Mine countermeasures (MCM) sensor technology drivers

NASA Astrophysics Data System (ADS)

Skinner, David P.

1995-06-01

In recent years, MCM has moved to the forefront of the Navy's attention. This paper describes the general problems that drive the technology requirements of classical sea mine countermeasure (MCM) sensors for those working outside of this specialized area. Sensor requirements for MCM are compared with those for antisubmarine warfare. This highlights the unique environmental issues and crucial false target problems. The elimination of false targets, not mine detection, is the principal driver of MCM sensor requirements and places special emphasis on the technologies needed for the sequential operations of detection, classification, and identification.

A multichip aVLSI system emulating orientation selectivity of primary visual cortical cells.

PubMed

Shimonomura, Kazuhiro; Yagi, Tetsuya

2005-07-01

In this paper, we designed and fabricated a multichip neuromorphic analog very large scale integrated (aVLSI) system, which emulates the orientation selective response of the simple cell in the primary visual cortex. The system consists of a silicon retina and an orientation chip. An image, which is filtered by a concentric center-surround (CS) antagonistic receptive field of the silicon retina, is transferred to the orientation chip. The image transfer from the silicon retina to the orientation chip is carried out with analog signals. The orientation chip selectively aggregates multiple pixels of the silicon retina, mimicking the feedforward model proposed by Hubel and Wiesel. The chip provides the orientation-selective (OS) outputs which are tuned to 0 degrees, 60 degrees, and 120 degrees. The feed-forward aggregation reduces the fixed pattern noise that is due to the mismatch of the transistors in the orientation chip. The spatial properties of the orientation selective response were examined in terms of the adjustable parameters of the chip, i.e., the number of aggregated pixels and size of the receptive field of the silicon retina. The multichip aVLSI architecture used in the present study can be applied to implement higher order cells such as the complex cell of the primary visual cortex.

Automated seismic waveform location using Multichannel Coherency Migration (MCM)-I. Theory

NASA Astrophysics Data System (ADS)

Shi, Peidong; Angus, Doug; Rost, Sebastian; Nowacki, Andy; Yuan, Sanyi

2018-03-01

With the proliferation of dense seismic networks sampling the full seismic wavefield, recorded seismic data volumes are getting bigger and automated analysis tools to locate seismic events are essential. Here, we propose a novel Multichannel Coherency Migration (MCM) method to locate earthquakes in continuous seismic data and reveal the location and origin time of seismic events directly from recorded waveforms. By continuously calculating the coherency between waveforms from different receiver pairs, MCM greatly expands the available information which can be used for event location. MCM does not require phase picking or phase identification, which allows fully automated waveform analysis. By migrating the coherency between waveforms, MCM leads to improved source energy focusing. We have tested and compared MCM to other migration-based methods in noise-free and noisy synthetic data. The tests and analysis show that MCM is noise resistant and can achieve more accurate results compared with other migration-based methods. MCM is able to suppress strong interference from other seismic sources occurring at a similar time and location. It can be used with arbitrary 3D velocity models and is able to obtain reasonable location results with smooth but inaccurate velocity models. MCM exhibits excellent location performance and can be easily parallelized giving it large potential to be developed as a real-time location method for very large datasets.

Enhancement in visible light photocatalytic activity by embedding Cu nanoparticles over CuS/MCM-41 nanocomposite

NASA Astrophysics Data System (ADS)

Sohrabnezhad, Sh.; Karamzadeh, M.

2017-07-01

This article indicate the biogenic synthesis of copper nanoparticles (Cu NPs) using the borage flowers extract of Borago officinalis over CuS/MCM-41 nanocomposite (NC). No external reducing was utilized in the developed method. The CuS-MCM-41 NC was used as stabilizing agent. The synthesis of CuS nanostructure in MCM-41 material has been realized by hydrothermal method. Their physiochemical properties have been characterized by X-ray diffraction, transmission electron microscopy (TEM), UV-Visible diffuse reflectance spectroscopy, and Fourier transform infrared spectroscopy. On the basis of TEM images, a layer of Cu NPs has been located over CuS/MCM-41 NC with average diameter of 60-80 nm. The results revealed the spherical nature of the prepared Cu NPs with diameter less than 10 nm. The DR spectra of Cu NPs in MCM-41 and CuS-MCM-41 NCs showed surface plasmon resonance bands at 570 and 500-600 nm, respectively. The photocatalytic activity was evaluated under visible light irradiation using the photocatalytic degradation of methylene blue (MB) as a model reaction. The prepared Cu/CuS/MCM-41 nanocomposite microspheres showed higher photodegradation ability for MB than CuS/MCM-41. The degradation of MB achieved up to 80% after 60 min and the nanocomposite could be recycled and reused.

78 FR 24803 - Hilco SP Rail, LLC-Acquisition and Operation Exemption-RG Steel Railroad Holding, LLC

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-26

... Point, Baltimore County, Md. (the Line). Hilco states that the operator of the Line will be MCM Rail Services LLC (MCM),\\1\\ and that MCM will interchange traffic with CSX Transportation, Inc. (CSXT), and... commitments in the agreement between MCM and Hilco, and that there will be no interchange agreements in the...

Reversal of DDK-Mediated MCM Phosphorylation by Rif1-PP1 Regulates Replication Initiation and Replisome Stability Independently of ATR/Chk1.

PubMed

Alver, Robert C; Chadha, Gaganmeet Singh; Gillespie, Peter J; Blow, J Julian

2017-03-07

Dbf4-dependent kinases (DDKs) are required for the initiation of DNA replication, their essential targets being the MCM2-7 proteins. We show that, in Xenopus laevis egg extracts and human cells, hyper-phosphorylation of DNA-bound Mcm4, but not phosphorylation of Mcm2, correlates with DNA replication. These phosphorylations are differentially affected by the DDK inhibitors PHA-767491 and XL413. We show that DDK-dependent MCM phosphorylation is reversed by protein phosphatase 1 (PP1) targeted to chromatin by Rif1. Loss of Rif1 increased MCM phosphorylation and the rate of replication initiation and also compromised the ability of cells to block initiation when challenged with replication inhibitors. We also provide evidence that Rif1 can mediate MCM dephosphorylation at replication forks and that the stability of dephosphorylated replisomes strongly depends on Chk1 activity. We propose that both replication initiation and replisome stability depend on MCM phosphorylation, which is maintained by a balance of DDK-dependent phosphorylation and Rif1-mediated dephosphorylation. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Rapid DNA replication origin licensing protects stem cell pluripotency

PubMed Central

Matson, Jacob Peter; Dumitru, Raluca; Coryell, Philip; Baxley, Ryan M; Chen, Weili; Twaroski, Kirk; Webber, Beau R; Tolar, Jakub; Bielinsky, Anja-Katrin; Purvis, Jeremy E

2017-01-01

Complete and robust human genome duplication requires loading minichromosome maintenance (MCM) helicase complexes at many DNA replication origins, an essential process termed origin licensing. Licensing is restricted to G1 phase of the cell cycle, but G1 length varies widely among cell types. Using quantitative single-cell analyses, we found that pluripotent stem cells with naturally short G1 phases load MCM much faster than their isogenic differentiated counterparts with long G1 phases. During the earliest stages of differentiation toward all lineages, MCM loading slows concurrently with G1 lengthening, revealing developmental control of MCM loading. In contrast, ectopic Cyclin E overproduction uncouples short G1 from fast MCM loading. Rapid licensing in stem cells is caused by accumulation of the MCM loading protein, Cdt1. Prematurely slowing MCM loading in pluripotent cells not only lengthens G1 but also accelerates differentiation. Thus, rapid origin licensing is an intrinsic characteristic of stem cells that contributes to pluripotency maintenance. PMID:29148972

Mesoporous silica (MCM-41)-Fe2O3 as a novel magnetic nanosensor for determination of trace amounts of amino acids.

PubMed

Hasanzadeh, Mohammad; Shadjou, Nasrin; Omidinia, Eskandar

2013-08-01

Magnetic (Fe2O3) mobile crystalline material-41 (MCM-41) was prepared and characterized using transmission electron microscopy (TEM) and nitrogen adsorption-desorption techniques. Due to the large surface area (1213 m(2)g(-1)) and remarkable electrocatalytic properties of MCM-41-Fe2O3, the MCM-41-Fe2O3 modified glassy carbon electrode (MCM-41-Fe2O3/GCE) exhibits potent electrocatalytic activity toward the electro-oxidation of amino acids. MCM-41-Fe2O3/GCE brings new capabilities for electrochemical sensing by combining the advantages of Fe2O3 magnetic nanoparticles and MCM-41 with very large surface area. Cyclic voltammetry, hydrodynamic amperometry and flow injection analysis used to determination of amino acids at higher concentration range. Fast response time, excellent catalytic activity, and ease of preparation are the advantages of the proposed amino acid sensor. Copyright © 2013 Elsevier B.V. All rights reserved.

GINS complex protein Sld5 recruits SIK1 to activate MCM helicase during DNA replication.

PubMed

Joshi, Kiranmai; Shah, Varun Jayeshkumar; Maddika, Subbareddy

2016-12-01

In eukaryotes, proper loading and activation of MCM helicase at chromosomal origins plays a central role in DNA replication. Activation of MCM helicase requires its association with CDC45-GINS complex, but the mechanism of how this complex activates MCM helicase is poorly understood. Here we identified SIK1 (salt-inducible kinase 1), an AMPK related protein kinase, as a molecular link that connects GINS complex with MCM helicase activity. We demonstrated that Sld5 a component of GINS complex interacts with SIK1 and recruits it to the sites of DNA replication at the onset of S phase. Depletion of SIK1 leads to defective DNA replication. Further, we showed that SIK1 phosphorylates MCM2 at five conserved residues at its N-terminus, which is essential for the activation of MCM helicase. Collectively, our results suggest SIK1 as a novel integral component of CMG replicative helicase during eukaryotic DNA replication. Copyright © 2016 Elsevier Inc. All rights reserved.

Enhanced photocatalytic hydrogen production from an MCM-41-immobilized photosensitizer-[Fe-Fe] hydrogenase mimic dyad.

PubMed

Wang, Wen; Yu, Tianjun; Zeng, Yi; Chen, Jinping; Yang, Guoqiang; Li, Yi

2014-11-01

A covalently linked photosensitizer-catalytic center dyad Ps-Hy, consisting of two bis(2-phenylpyridine)(2,2'-bipyridine)iridium(iii) chromophores (Ps) and a diiron hydrogenase mimic (Hy) was constructed by using click reaction. Ps-Hy was incorporated into K(+)-exchanged molecular sieve MCM-41 to form a composite (Ps-Hy@MCM-41), which has been successfully applied to the photochemical production of hydrogen. The catalytic activity of Ps-Hy@MCM-41 is ∼3-fold higher as compared with that of Ps-Hy in the absence of MCM-41. The incorporation of Ps-Hy into MCM-41 stabilizes the catalyst, and consequently, advances the photocatalysis. The present study provides a potential strategy for improving catalytic efficiency of artificial photosynthesis systems using mesoporous molecular sieves.

Expression of MCM-3 and MCM-7 in Primary Cutaneous T-cell Lymphomas.

PubMed

Jankowska-Konsur, Alina; Kobierzycki, Christopher; Reich, Adam; Grzegrzolka, Jedrzej; Maj, Joanna; Dziegiel, Piotr

2015-11-01

Primary cutaneous T-cell lymphomas is a group of rare non-Hodgkin lymphomas, originally affecting the skin. Increased proliferation activity is a hallmark of diverse tumors and the proliferation rate, measured by the expression of various markers has a predictive value regarding the malignancy course. The aim of the present study was to evaluate the prognostic value and the potential correlation between the expression of proliferation markers Ki-67, MCM-3 and MCM-7, and clinicopathological data for different types of primary cutaneous T-cell lymphomas. Immunohistochemical reactions were performed on paraffin blocks obtained from 90 patients with mycosis fungoides (MF) and 21 patients with other CTCL (oCTCL), in comparison to 19 patients with benign inflammatory dermatosis (lichen planus, eczema), serving as control. Statistically significant differences in the expression of Ki-67, MCM-3 and MCM-7 were observed between oCTCL vs. the control group (29% vs. 5%; 17% vs. 5%; 13% vs. 1.5%, respectively, ANOVA with Scheffé post-hoc test: p<0.01). In both, MF and oCTCL Ki-67 expression highly correlated with the expression of MCM-3 (r=0.83; p<0.001 and r=0.91; p<0.001, respectively) and MCM-7 (r=0.84; p<0.001 and r=0.87; p<0.01, respectively; Pearson correlation test). Similarly, a strong positive correlation was observed between MCM-3 and MCM-7 (r=0.81, p<0.001 and r=0.85, p<0.001). Regarding the MF group, Ki-67 and MCM-3 expression was significantly higher in advanced compared to early stages (11% vs. 3% and 15.5% vs. 5.0%, respectively, Student's t-test: p<0.05). Advanced MF had also significantly higher labeling indexes for Ki-67, MCM-3 and MCM-7 compared to benign inflammatory dermatoses (Student's t-test: p<0.01, p<0.001 and p=0.02, respectively). Considering skin involvement in MF, T1b had a significantly higher expression of Ki-67, MCM-3 and MCM-7 than T1a (p<0.001 for all comparisons) with similar observations between T2b and T2a (p=0.02; p<0.01; p=0.01, respectively, Student's t-test test). Regarding extracutaneous involvement, only MCM-3 expression in MF showed a positive relationship with both nodal and distant metastases (ANOVA with Scheffé post hoc test: p<0.01, p<0.01, respectively). Higher Ki-67 and MCM-3 expression correlated with shorter survival in MF, although the latter did not reach statistical significance (10-year survival 0.38 vs. 0.82, p=0.02, and 0.46 vs. 0.81, p=0.06, respectively; log rank test). All studied proliferation markers may had predictive values regarding the disease severity and prognosis. Further studies are required to analyze their implementation into patient stratification and treatment process such that will improve prognosis in CTCL. Copyright© 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

Sulfuric acid functional zirconium (or aluminum) incorporated mesoporous MCM-48 solid acid catalysts for alkylation of phenol with tert-butyl alcohol

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Tingshun, E-mail: tshjiang@mail.ujs.edu.cn; Cheng, Jinlian; Liu, Wangping

2014-10-15

Several zirconium (or aluminum) incorporated mesoporous MCM-48 solid acid catalysts (SO{sub 4}{sup 2−}/Zr-MCM-48 and SO{sub 4}{sup 2−}/Al-MCM-48) were prepared by the impregnation method and their physicochemical properties were characterized by means of XRD, FT-IR, TEM, NH{sub 3}-TPD and N{sub 2} physical adsorption. Also, the catalytic activities of these solid acid catalysts were evaluated by the alkylation of phenol with tert-butyl alcohol. The effect of weight hour space velocity (WHSV), reaction time and reaction temperature on catalytic properties was also studied. The results show that the SO{sub 4}{sup 2−}/Zr-MCM-48 and SO{sub 4}{sup 2−}/Al-MCM-48 still have good mesoporous structure and long rangemore » ordering. Compared with the Zr (or Al)–MCM-48 samples, SO{sub 4}{sup 2−}/Zr-MCM-48 and SO{sub 4}{sup 2−}/Al-MCM-48 solid acid catalysts have strong acidity and exhibit high activities in alkylation reaction of phenol with tert-butyl alcohol. The SO{sub 4}{sup 2−}/Zr-MCM-48-25 (molar ratio of Si/Zr=0.04) catalyst was found to be the most promising and gave the highest phenol conversion among all catalysts. A maximum phenol conversion of 91.6% with 4-tert-butyl phenol (4-TBP) selectivity of 81.8% was achieved when the molar ratio of tert-butyl alcohol:phenol is 2:1, reaction time is 2 h, the WHSV is 2 h{sup −1} and the reaction temperature is 140 °C. - Highlights: • Sulfuric acid functional mesoporous solid acid catalysts were prepared via impregnation method. • The alkylation of phenol with tert-butyl alcohol was carried out over these solid acid catalysts. • The catalytic activity of SO{sub 4}{sup 2−}/Zr-MCM-48-25 catalyst is much higher than that of the others. • A maximum phenol conversion of 91.6% was achieved under optimum reaction conditions for SO{sub 4}{sup 2−}/Zr-MCM-48-25.« less

Controlled release of metformin from chitosan-based nanocomposite films containing mesoporous MCM-41 nanoparticles as novel drug delivery systems.

PubMed

Shariatinia, Zahra; Zahraee, Zahra

2017-09-01

Biocompatible nanocomposite films based on blended chitosan and poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (BP) polymers containing metformin (MET) drug and MCM-41 or MCM-41-APS (APS=aminopropylsilane) nanoparticles (NPs) were designed and fabricated in order to prepare novel drug delivery systems which are useful for controlled drug release purposes. The total pore volume and mesopore volume of MCM-41 were measured equal to 1.08 and 1.05 cm 3 /g but those of MCM-41-APS were 0.54 and 0.26 cm 3 /g indicating smaller values for the APS functionalized material. The film thickness was the highest for CS-BP-G-10%MET (70μm) but it was the smallest for the CS-BP-G-4%MCM-41 (49μm). For all of the films, the swelling percent was the highest in acidic medium but it was decreased in PBS and the least water uptake occurred in the alkaline environment. The lowest and the highest water uptake was observed for the films incorporated with 4%MCM-41NPs and 4%MCM-41-APS-10%MET, respectively. The SEM micrographs of the films after three days water uptake in pH=4 medium exhibited that all of the films were stable against cracking and/or tearing. It was found that increasing the MCM-41 or MCM-41-APS amount within the films decreased the elongation at break but enhanced the tensile stress. The release of the MET was sharply increased within ∼22-24h (burst release) but after that the drug release was slowly enhanced during 15days (sustained release). Finally, it was concluded that the film 4% MCM-41-APS-10%MET NPs was the most promising drug delivery system because it had improved hydrophilicity, hydrolytic stability, biocompatibility, mechanical and drug release properties. Copyright © 2017 Elsevier Inc. All rights reserved.

Selective attention in multi-chip address-event systems.

PubMed

Bartolozzi, Chiara; Indiveri, Giacomo

2009-01-01

Selective attention is the strategy used by biological systems to cope with the inherent limits in their available computational resources, in order to efficiently process sensory information. The same strategy can be used in artificial systems that have to process vast amounts of sensory data with limited resources. In this paper we present a neuromorphic VLSI device, the "Selective Attention Chip" (SAC), which can be used to implement these models in multi-chip address-event systems. We also describe a real-time sensory-motor system, which integrates the SAC with a dynamic vision sensor and a robotic actuator. We present experimental results from each component in the system, and demonstrate how the complete system implements a real-time stimulus-driven selective attention model.

Preparation of TiO2/MCM-41 photocatalyst using rice husk ash as silica source

NASA Astrophysics Data System (ADS)

Fatimah, Is; Sopia, Lusi

2017-03-01

This work aimed to prepare TiO2/MCM-41 from rice husk ash (RHA) agricultural waste and its application as photocatalyst in dye degradation. The preparation was conducted by two main steps; preparation of MCM-41 and titanium immobilization onto MCM-41. Sol gel method using CTMABr as templating agent was applied in MCM-41 synthesis and as TiO2 precursor, titanium isopropoxide was utilized. The study of physicochemical character change was performed by by X-ray diffraction, IR spectroscopy, BET method and thermogravimetric analysis (TGA). Photocatalytic activity of material was tested in methylene blue photodegradation system. According to the results, it is found that TiO2/MCM-41 has been successfully prepared and shows photocatalytic activity. Kinetic study of the reaction is discussed in this paper.

Green synthesis of mesoporous molecular sieve incorporated monoliths using room temperature ionic liquid and deep eutectic solvents.

PubMed

Zhang, Li-Shun; Zhao, Qing-Li; Li, Xin-Xin; Li, Xi-Xi; Huang, Yan-Ping; Liu, Zhao-Sheng

2016-12-01

A hybrid monolith incorporated with mesoporous molecular sieve MCM-41 of uniform pore structure and high surface area was prepared with binary green porogens in the first time. With a mixture of room temperature ionic liquids and deep eutectic solvents as porogens, MCM-41 was modified with 3-(trimethoxysilyl) propyl methacrylate (γ-MPS) and the resulting MCM-41-MPS was incorporated into poly (BMA-co-EDMA) monoliths covalently. Because of good dispersibility of MCM-41-MPS in the green solvent-based polymerization system, high permeability and homogeneity for the resultant hybrid monolithic columns was achieved. The MCM-41-MPS grafted monolith was characterized by scanning electron microscopy, energy dispersive spectrometer area scanning, transmission electron microscopy, FT-IR spectra and nitrogen adsorption tests. Chromatographic performance of MCM-41-MPS grafted monolith was characterized by separating small molecules in capillary electrochromatography, including phenol series, naphthyl substitutes, aniline series and alkyl benzenes. The maximum column efficiency of MCM-41-MPS grafted monolith reached 209,000 plates/m, which was twice higher than the corresponding MCM-41-MPS free monolith. Moreover, successful separation of non-steroidal anti-inflammatory drugs and polycyclic aromatic hydrocarbons demonstrated the capacity in broad-spectrum application of the MCM-41-MPS incorporated monolith. The results indicated that green synthesis using room temperature ionic liquid and deep eutectic solvents is an effective method to prepare molecular sieve-incorporated monolithic column. Copyright © 2016 Elsevier B.V. All rights reserved.

The DNA replication licensing factor miniature chromosome maintenance 7 is essential for RNA splicing of epidermal growth factor receptor, c-Met, and platelet-derived growth factor receptor.

PubMed

Chen, Zhang-Hui; Yu, Yan P; Michalopoulos, George; Nelson, Joel; Luo, Jian-Hua

2015-01-16

Miniature chromosome maintenance 7 (MCM7) is an essential component of DNA replication licensing complex. Recent studies indicate that MCM7 is amplified and overexpressed in a variety of human malignancies. In this report, we show that MCM7 binds SF3B3. The binding motif is located in the N terminus (amino acids 221-248) of MCM7. Knockdown of MCM7 or SF3B3 significantly increased unspliced RNA of epidermal growth factor receptor, platelet-derived growth factor receptor, and c-Met. A dramatic drop of reporter gene expression of the oxytocin exon 1-intron-exon 2-EGFP construct was also identified in SF3B3 and MCM7 knockdown PC3 and DU145 cells. The MCM7 or SF3B3 depleted cell extract failed to splice reporter RNA in in vitro RNA splicing analyses. Knockdown of SF3B3 and MCM7 leads to an increase of cell death of both PC3 and DU145 cells. Such cell death induction is partially rescued by expressing spliced c-Met. To our knowledge, this is the first report suggesting that MCM7 is a critical RNA splicing factor, thus giving significant new insight into the oncogenic activity of this protein. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

How MCM loading and spreading specify eukaryotic DNA replication initiation sites.

PubMed

Hyrien, Olivier

2016-01-01

DNA replication origins strikingly differ between eukaryotic species and cell types. Origins are localized and can be highly efficient in budding yeast, are randomly located in early fly and frog embryos, which do not transcribe their genomes, and are clustered in broad (10-100 kb) non-transcribed zones, frequently abutting transcribed genes, in mammalian cells. Nonetheless, in all cases, origins are established during the G1-phase of the cell cycle by the loading of double hexamers of the Mcm 2-7 proteins (MCM DHs), the core of the replicative helicase. MCM DH activation in S-phase leads to origin unwinding, polymerase recruitment, and initiation of bidirectional DNA synthesis. Although MCM DHs are initially loaded at sites defined by the binding of the origin recognition complex (ORC), they ultimately bind chromatin in much greater numbers than ORC and only a fraction are activated in any one S-phase. Data suggest that the multiplicity and functional redundancy of MCM DHs provide robustness to the replication process and affect replication time and that MCM DHs can slide along the DNA and spread over large distances around the ORC. Recent studies further show that MCM DHs are displaced along the DNA by collision with transcription complexes but remain functional for initiation after displacement. Therefore, eukaryotic DNA replication relies on intrinsically mobile and flexible origins, a strategy fundamentally different from bacteria but conserved from yeast to human. These properties of MCM DHs likely contribute to the establishment of broad, intergenic replication initiation zones in higher eukaryotes.

Quick photo-Fenton degradation of phenolic compounds by Cu/Al2O3-MCM-41 under visible light irradiation: small particle size, stabilization of copper, easy reducibility of Cu and visible light active material.

PubMed

Pradhan, Amaresh C; Nanda, Binita; Parida, K M; Das, Mira

2013-01-14

The present study reports the photo-Fenton degradation of phenolic compounds (phenol, 2-chloro-4-nitrophenol and 4-chloro-2-nitrophenol) in aqueous solution using mesoporous Cu/Al(2)O(3)-MCM-41 nanocomposite as a heterogeneous photo-Fenton-like catalyst. The in situ incorporation of mesoporous Al(2)O(3) (MA) into the framework of MCM-41 (sol-gel method) forms Al(2)O(3)-MCM-41 and wetness impregnation of Cu(II) on Al(2)O(3)-MCM-41 generates mesoporous Cu/Al(2)O(3)-MCM-41 composite. The effects of pH and H(2)O(2) concentration on degradation of phenol, 2-chloro-4-nitrophenol and 4-chloro-2-nitrophenol are studied. Kinetics analysis shows that the photocatalytic degradation reaction follows a first-order rate equation. Mesoporous 5 Cu/Al(2)O(3)-MCM-41 is found to be an efficient photo-Fenton-like catalyst for the degradation of phenolic compounds. It shows nearly 100% degradation in 45 min at pH 4. The combined effect of small particle size, stabilization of Cu(2+) on the support Al(2)O(3)-MCM-41, ease reducibility of Cu(2+) and visible light activeness are the key factors for quick degradation of phenolic compounds by Cu/Al(2)O(3)-MCM-41.

Application of as-synthesised MCM-41 and MCM-41 wrapped with reduced graphene oxide/graphene oxide in the remediation of acetaminophen and aspirin from aqueous system.

PubMed

Akpotu, Samson O; Moodley, Brenda

2018-03-01

In this study, ASM41 (as-synthesised MCM-41), MCM-41, MCM-41 encapsulated with graphene oxide (MCM-41-GO) and reduced graphene oxide (MCM-41-G) were fabricated and utilized in the remediation of acetaminophen and aspirin from water. A surfactant template (cetyltrimethylammonium bromide) was added to ASM41 to make it more hydrophobic and its effects on the remediation of acetaminophen and aspirin from wastewater was studied. To further improve the adsorption capacity of the adsorbent, MCM-41 was encapsulated with GO and G which also aided in easy separation of the adsorbent from the aqueous solution. Comparative studies of the adsorption of acetaminophen and aspirin on all four adsorbents were investigated. Batch adsorption studies of acetaminophen and aspirin were carried out to determine the effects of pH, initial concentration, time and adsorbent dose. Adsorption mechanism was through EDA, π-π interactions, and hydrophobic effects. Data from sorption kinetics showed ASM41 had the highest q m value for aspirin (909.1 mg/g) and MCM-41-G had the highest q m value for acetaminophen (555.6 mg/g). The significant adsorption by ASM41 can be attributed to increased hydrophobicity due to the retention of the surfactant template. Thermodynamic studies revealed the adsorption process as spontaneous and exothermic. Desorption studies revealed that adsorbents could be regenerated and reused for adsorption. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synergistic Effect of Graphene Oxide and Mesoporous Structure on Flame Retardancy of Nature Rubber/IFR Composites.

PubMed

Wang, Na; Zhang, Miao; Kang, Ping; Zhang, Jing; Fang, Qinghong; Li, Wenda

2018-06-13

Aiming to improve the flame retardancy performance of natural rubber (NR), we developed a novel flame retardant synergistic agent through grafting of MCM-41 to graphene oxide (GO), named as GO-NH-MCM-41, as an assistant to intumescent flame retardants (IFR). The flame retardancy of NR/IFR/GO-NH-MCM-41 composites was evaluated by limited oxygen index (LOI), UL-94, and cone calorimeter test. The LOI value of NR/IFR/GO-NH-MCM-41 reached 26.3%; the UL-94 ratings improved to a V-0 rating. Moreover, the addition of GO-NH-MCM-41 decreased the peak heat release rate (PHRR) and the total heat release (THR) of the natural rubber composites. Furthermore, the addition of GO-NH-MCM-41 increased the thickness of char residue. The images of SEM indicated the char residue was more compact and continuous. The degradation of GO-NH-MCM-41-based NR composites was completed with a mass loss of 35.57% at 600 °C. The tensile strength and the elongation at break of the NR/IFR/GO-NH-MCM-41 composites were 13.9 MPa and 496.7%, respectively. The results of the rubber process analyzer (RPA) reached the maximum value, probably due to a better network of fillers in the matrix.

Acute inactivation of the replicative helicase in human cells triggers MCM8–9-dependent DNA synthesis

PubMed Central

Natsume, Toyoaki; Nishimura, Kohei; Minocherhomji, Sheroy; Bhowmick, Rahul; Hickson, Ian D.; Kanemaki, Masato T.

2017-01-01

DNA replication fork progression can be disrupted at difficult to replicate loci in the human genome, which has the potential to challenge chromosome integrity. This replication fork disruption can lead to the dissociation of the replisome and the formation of DNA damage. To model the events stemming from replisome dissociation during DNA replication perturbation, we used a degron-based system for inducible proteolysis of a subunit of the replicative helicase. We show that MCM2-depleted cells activate a DNA damage response pathway and generate replication-associated DNA double-strand breaks (DSBs). Remarkably, these cells maintain some DNA synthesis in the absence of MCM2, and this requires the MCM8–9 complex, a paralog of the MCM2–7 replicative helicase. We show that MCM8–9 functions in a homologous recombination-based pathway downstream from RAD51, which is promoted by DSB induction. This RAD51/MCM8–9 axis is distinct from the recently described RAD52-dependent DNA synthesis pathway that operates in early mitosis at common fragile sites. We propose that stalled replication forks can be restarted in S phase via homologous recombination using MCM8–9 as an alternative replicative helicase. PMID:28487407

A method to improve the accuracy of pair-wise combinations of anthropometric elements when only limited data are available.

PubMed

Albin, Thomas J

2013-01-01

Designers and ergonomists occasionally must produce anthropometric models of workstations with only summary percentile data available regarding the intended users. Until now the only option available was adding or subtracting percentiles of the anthropometric elements, e.g. heights and widths, used in the model, despite the known resultant errors in the estimate of the percent of users accommodated. This paper introduces a new method, the Median Correlation Method (MCM) that reduces the error. Compare the relative accuracy of MCM to combining percentiles for anthropometric models comprised of all possible pairs of five anthropometric elements. Describe the mathematical basis of the greater accuracy of MCM. MCM is described. 95th percentile accommodation percentiles are calculated for the sums and differences of all combinations of five anthropometric elements by combining percentiles and using MCM. The resulting estimates are compared with empirical values of the 95th percentiles, and the relative errors are reported. The MCM method is shown to be significantly more accurate than adding percentiles. MCM is demonstrated to have a mathematical advantage estimating accommodation relative to adding or subtracting percentiles. The MCM method should be used in preference to adding or subtracting percentiles when limited data prevent more sophisticated anthropometric models.

Mesoporous silica nanocarriers encapsulated antimalarials with high therapeutic performance.

PubMed

Amolegbe, Saliu Alao; Hirano, Yui; Adebayo, Joseph Oluwatope; Ademowo, Olusegun George; Balogun, Elizabeth Abidemi; Obaleye, Joshua Ayoola; Krettli, Antoniana Ursine; Yu, Chengzhong; Hayami, Shinya

2018-02-15

The use of nanocarriers in drug delivery is a breakeven research and has received a clarion call in biomedicine globally. Herein, two newly nano-biomaterials: MCM-41 encapsulated quinine (MCM-41 ⊃ QN) (1) and 3-phenylpropyl silane functionalized MCM-41 loaded QN (pMCM-41 ⊃ QN) (2) were synthesized and well characterized. 1 and 2 along with our two already reported nano-antimalarial drugs (MCM-41 ⊃ ATS) (3) and 3-aminopropyl silane functionalized MCM-41 contained ATS (aMCM-41 ⊃ ATS) (4) were screened in vitro for their activity against P. falciparium W2 strain, cytotoxicity against BGM cells and in vivo for their activity against Plasmodium bergheiNK65. 1 has the highest antimalarial activity in vivo against P. berghei NK65, (ED 50 : < 0.0625 mg/kg body weight) and higher mean survival time compared to the other nano biomaterials or unencapsulated drugs at doses higher than 0.0625 mg/kg body weight. This encapsulation strategy of MCM-41 ⊃ QN (1) stands very useful and effective in delivering the drug to the target cells compared to other delivery systems and therefore, this encapsulated drug may be considered for rational drug design.

Application of ToF-SIMS to the study of surfactant removal from AuNbMCM-41 and AuMCM-41 materials

NASA Astrophysics Data System (ADS)

Grams, Jacek; Sobczak, Izabela

2010-01-01

This work is focused on the application of time-of-flight secondary ion mass spectrometry (ToF-SIMS) in investigation of the surfactant removal process from AuNbMCM-41 and AuMCM-41 catalysts (MCM-41 "Mobil Composition of Matter", ordered mesoporous materials discovered by Mobil R&D Corporation). The samples investigated were prepared by co-precipitation in the presence of a cationic surfactant (cetyltrimethylammonium chloride--CH3(CH2)15N(Cl)(CH3)3) and the incipient wetness impregnation methods. The results obtained showed that the time-of-flight secondary ion mass spectrometry appears to be a very useful tool for the investigation of the residual organic template on the surface of ordered mesoporous materials of MCM-41 type. It was demonstrated that the calcination of AuNbMCM-41 and AuMCM-41 catalysts at 550 °C caused a complete removal of the surfactant from the surface of the material investigated. Moreover, it was shown that the use of bismuth liquid metal ion gun in ToF-SIMS experiments permitted obtaining higher emission intensity (more than one order of magnitude when compared to the Ga+ primary ion source) of secondary ions originating from the surfactant molecules and may facilitate an interpretation of the results obtained.

Catalytic Oxidation of Vanillyl Alcohol Using FeMCM-41 Nanoporous Tubular Reactor

NASA Astrophysics Data System (ADS)

Elamathi, P.; Kolli, Murali Krishna; Chandrasekar, G.

Iron containing nanoporous MCM-41 (FeMCM-41) with different Si/Fe ratios of 50, 100 and 150 was synthesized by hydrothermal synthesis process. The materials obtained from hydrothermal synthesis were characterized by various physico chemical techniques such as XRD, N2 adsorption, DR UV-vis, EPR and FTIR spectroscopy. XRD analyses of FeMCM-41 materials confirmed the presence of well-ordered crystalline structure. N2 isotherm of FeMCM-41 materials showed type IV adsorption isotherm. EPR and DR UV-vis analysis of FeMCM-41 samples indicates the presence of high tetrahedral coordination at the Si/Fe ratios of 100 and 150. The catalytic performance of FeMCM-41 nano tubular reactor was tested in the liquid phase oxidation of vanillyl alcohol into vanillin using H2O2 (50wt% in water). The reaction products were analyzed by gas chromatography in DB-5 capillary column with flame ionization detector. The products were confirmed by 1H NMR, 13C NMR and LC-Mass spectroscopy. The maximum conversion of vanillyl alcohol (85%) and selectivity towards vanillin (82%) were observed using the catalyst FeMCM-41(100) in 30min at 60∘C. The influence of reaction temperature, reaction time, reactants molar ratio, Si/Fe ratio and amount of catalyst were investigated.

Adsorption of Pb2+ on Thiol-functionalized Mesoporous Silica, SH-MCM-48

NASA Astrophysics Data System (ADS)

Taba, P.; Mustafa, R. D. P.; Ramang, L. M.; Kasim, A. H.

2018-03-01

Modification of mesoporous silica, MCM-48, by using 3- mercaptopropyltrimethoxysilane has been successfully conducted. MCM-48 and SH-MCM-48 were characterized using XRD and FTIR. SH-MCM-48 was used as an adsorbent of Pb2+ ions from solution. A number of Pb2+ ions adsorbed were studied as the function of time, pH, and concentration. The concentration of the ions after adsorption was determined by an Atomic Absorption Spectrophotometer. The removal of the adsorbed ions from the SH-MCM-48 was also studied using several desorbing agents. The result showed that the optimum time was 20 minutes and optimum pH was 4. The adsorption of Pb(II) ion followed the pseudo-second-order with the rate constant of 0,2632 g•mg-1•min-1. Adsorption of Pb(II) ion fitted the Langmuir isotherm with the adsorption capacity of 0,1088 mmol/g. The best desorbing agent to remove the adsorbed ion from SH-MCM-48 was 0.3 M HCl solution with the desorption percentage of 58.6%.

Vertically integrated photonic multichip module architecture for vision applications

NASA Astrophysics Data System (ADS)

Tanguay, Armand R., Jr.; Jenkins, B. Keith; von der Malsburg, Christoph; Mel, Bartlett; Holt, Gary; O'Brien, John D.; Biederman, Irving; Madhukar, Anupam; Nasiatka, Patrick; Huang, Yunsong

2000-05-01

The development of a truly smart camera, with inherent capability for low latency semi-autonomous object recognition, tracking, and optimal image capture, has remained an elusive goal notwithstanding tremendous advances in the processing power afforded by VLSI technologies. These features are essential for a number of emerging multimedia- based applications, including enhanced augmented reality systems. Recent advances in understanding of the mechanisms of biological vision systems, together with similar advances in hybrid electronic/photonic packaging technology, offer the possibility of artificial biologically-inspired vision systems with significantly different, yet complementary, strengths and weaknesses. We describe herein several system implementation architectures based on spatial and temporal integration techniques within a multilayered structure, as well as the corresponding hardware implementation of these architectures based on the hybrid vertical integration of multiple silicon VLSI vision chips by means of dense 3D photonic interconnections.

SAR processing using SHARC signal processing systems

NASA Astrophysics Data System (ADS)

Huxtable, Barton D.; Jackson, Christopher R.; Skaron, Steve A.

1998-09-01

Synthetic aperture radar (SAR) is uniquely suited to help solve the Search and Rescue problem since it can be utilized either day or night and through both dense fog or thick cloud cover. Other papers in this session, and in this session in 1997, describe the various SAR image processing algorithms that are being developed and evaluated within the Search and Rescue Program. All of these approaches to using SAR data require substantial amounts of digital signal processing: for the SAR image formation, and possibly for the subsequent image processing. In recognition of the demanding processing that will be required for an operational Search and Rescue Data Processing System (SARDPS), NASA/Goddard Space Flight Center and NASA/Stennis Space Center are conducting a technology demonstration utilizing SHARC multi-chip modules from Boeing to perform SAR image formation processing.

Trade-offs between lens complexity and real estate utilization in a free-space multichip global interconnection module.

PubMed

Milojkovic, Predrag; Christensen, Marc P; Haney, Michael W

2006-07-01

The FAST-Net (Free-space Accelerator for Switching Terabit Networks) concept uses an array of wide-field-of-view imaging lenses to realize a high-density shuffle interconnect pattern across an array of smart-pixel integrated circuits. To simplify the optics we evaluated the efficiency gained in replacing spherical surfaces with aspherical surfaces by exploiting the large disparity between narrow vertical cavity surface emitting laser (VCSEL) beams and the wide field of view of the imaging optics. We then analyzed trade-offs between lens complexity and chip real estate utilization and determined that there exists an optimal numerical aperture for VCSELs that maximizes their area density. The results provide a general framework for the design of wide-field-of-view free-space interconnection systems that incorporate high-density VCSEL arrays.

CVD diamond substrate for microelectronics. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burden, J.; Gat, R.

1996-11-01

Chemical Vapor Deposition (CVD) of diamond films has evolved dramatically in recent years, and commercial opportunities for diamond substrates in thermal management applications are promising. The objective of this technology transfer initiative (TTI) is for Applied Science and Technology, Inc. (ASTEX) and AlliedSignal Federal Manufacturing and Technologies (FM&T) to jointly develop and document the manufacturing processes and procedures required for the fabrication of multichip module circuits using CVD diamond substrates, with the major emphasis of the project concentrating on lapping/polishing prior to metallization. ASTEX would provide diamond films for the study, and FM&T would use its experience in lapping, polishing,more » and substrate metallization to perform secondary processing on the parts. The primary goal of the project was to establish manufacturing processes that lower the manufacturing cost sufficiently to enable broad commercialization of the technology.« less

High temperature charge amplifier for geothermal applications

DOEpatents

Lindblom, Scott C.; Maldonado, Frank J.; Henfling, Joseph A.

2015-12-08

An amplifier circuit in a multi-chip module includes a charge to voltage converter circuit, a voltage amplifier a low pass filter and a voltage to current converter. The charge to voltage converter receives a signal representing an electrical charge and generates a voltage signal proportional to the input signal. The voltage amplifier receives the voltage signal from the charge to voltage converter, then amplifies the voltage signal by the gain factor to output an amplified voltage signal. The lowpass filter passes low frequency components of the amplified voltage signal and attenuates frequency components greater than a cutoff frequency. The voltage to current converter receives the output signal of the lowpass filter and converts the output signal to a current output signal; wherein an amplifier circuit output is selectable between the output signal of the lowpass filter and the current output signal.

Aluminum Doped MCM-41 Nanoparticles as Platforms for the Dual Encapsulation of a CO-Releasing Molecule and Cisplatin.

PubMed

Carmona, Francisco J; Jiménez-Amezcua, Ignacio; Rojas, Sara; Romão, Carlos C; Navarro, Jorge A R; Maldonado, Carmen R; Barea, Elisa

2017-09-05

Mesoporous silica Al-MCM-41 nanoparticles have been used, for the first time, as vehicles for the single and dual encapsulation of the cationic CO-releasing molecule (CORM) [Mn(1,4,7-triazacyclononane)(CO) 3 ] + (ALF472 + ) and the well-known antineoplastic drug, cis-[PtCl 2 (NH 3 ) 2 ] (cisplatin). Thus, two new hybrid materials, namely, ALF472@Al-MCM-41 and ALF472-cisplatin@Al-MCM-41, have been isolated and fully characterized. The results reveal that the presence of CORM molecules enhances cisplatin loading 3-fold, yielding a cargo of 0.45 mmol g -1 of ALF472 + and 0.12 mmol g -1 of the platinum complex for ALF472-cisplatin@Al-MCM-41. It is worth noting that ALF472@Al-MCM-41 shows a good dispersion in phosphate buffered saline solution, while the dual hybrid material slightly aggregates in this simulated physiological medium (hydrodynamic size: 112 ± 23 and 336 ± 50 nm, respectively). In addition, both hybrid materials (ALF472@Al-MCM-41 and ALF472-cisplatin@Al-MCM-41) behave as photoactive CO-releasing materials, delivering 0.25 and 0.11 equiv of CO, respectively, after 24 h and exhibiting a more controlled CO delivery than that of the free CORM. Finally, metal leaching studies have confirmed the good retention capacity of Al-MCM-41 toward the potentially toxic manganese fragments (86% of retention after 72 h) as well as the low release of cisplatin (ca. 7% after 72 h).

A Dominantly Acting Murine Allele of Mcm4 Causes Chromosomal Abnormalities and Promotes Tumorigenesis

PubMed Central

Bagley, Bruce N.; Keane, Thomas M.; Maklakova, Vilena I.; Marshall, Jonathon G.; Lester, Rachael A.; Cancel, Michelle M.; Paulsen, Alex R.; Bendzick, Laura E.; Been, Raha A.; Kogan, Scott C.; Cormier, Robert T.; Kendziorski, Christina; Adams, David J.; Collier, Lara S.

2012-01-01

Here we report the isolation of a murine model for heritable T cell lymphoblastic leukemia/lymphoma (T-ALL) called Spontaneous dominant leukemia (Sdl). Sdl heterozygous mice develop disease with a short latency and high penetrance, while mice homozygous for the mutation die early during embryonic development. Sdl mice exhibit an increase in the frequency of micronucleated reticulocytes, and T-ALLs from Sdl mice harbor small amplifications and deletions, including activating deletions at the Notch1 locus. Using exome sequencing it was determined that Sdl mice harbor a spontaneously acquired mutation in Mcm4 (Mcm4D573H). MCM4 is part of the heterohexameric complex of MCM2–7 that is important for licensing of DNA origins prior to S phase and also serves as the core of the replicative helicase that unwinds DNA at replication forks. Previous studies in murine models have discovered that genetic reductions of MCM complex levels promote tumor formation by causing genomic instability. However, Sdl mice possess normal levels of Mcms, and there is no evidence for loss-of-heterozygosity at the Mcm4 locus in Sdl leukemias. Studies in Saccharomyces cerevisiae indicate that the Sdl mutation produces a biologically inactive helicase. Together, these data support a model in which chromosomal abnormalities in Sdl mice result from the ability of MCM4D573H to incorporate into MCM complexes and render them inactive. Our studies indicate that dominantly acting alleles of MCMs can be compatible with viability but have dramatic oncogenic consequences by causing chromosomal abnormalities. PMID:23133403

A dominantly acting murine allele of Mcm4 causes chromosomal abnormalities and promotes tumorigenesis.

PubMed

Bagley, Bruce N; Keane, Thomas M; Maklakova, Vilena I; Marshall, Jonathon G; Lester, Rachael A; Cancel, Michelle M; Paulsen, Alex R; Bendzick, Laura E; Been, Raha A; Kogan, Scott C; Cormier, Robert T; Kendziorski, Christina; Adams, David J; Collier, Lara S

2012-01-01

Here we report the isolation of a murine model for heritable T cell lymphoblastic leukemia/lymphoma (T-ALL) called Spontaneous dominant leukemia (Sdl). Sdl heterozygous mice develop disease with a short latency and high penetrance, while mice homozygous for the mutation die early during embryonic development. Sdl mice exhibit an increase in the frequency of micronucleated reticulocytes, and T-ALLs from Sdl mice harbor small amplifications and deletions, including activating deletions at the Notch1 locus. Using exome sequencing it was determined that Sdl mice harbor a spontaneously acquired mutation in Mcm4 (Mcm4(D573H)). MCM4 is part of the heterohexameric complex of MCM2-7 that is important for licensing of DNA origins prior to S phase and also serves as the core of the replicative helicase that unwinds DNA at replication forks. Previous studies in murine models have discovered that genetic reductions of MCM complex levels promote tumor formation by causing genomic instability. However, Sdl mice possess normal levels of Mcms, and there is no evidence for loss-of-heterozygosity at the Mcm4 locus in Sdl leukemias. Studies in Saccharomyces cerevisiae indicate that the Sdl mutation produces a biologically inactive helicase. Together, these data support a model in which chromosomal abnormalities in Sdl mice result from the ability of MCM4(D573H) to incorporate into MCM complexes and render them inactive. Our studies indicate that dominantly acting alleles of MCMs can be compatible with viability but have dramatic oncogenic consequences by causing chromosomal abnormalities.

Suppression of Reserve MCM Complexes Chemosensitizes to Gemcitabine and 5-Fluorouracil

PubMed Central

Bryant, Victoria L.; Elias, Roy M.; McCarthy, Susan M.; Yeatman, Timothy J.; Alexandrow, Mark G.

2015-01-01

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest forms of cancer and is very difficult to treat with conventional chemotherapeutic regimens. Gemcitabine and 5-fluorouracil (5-FU) are used in the management of PDAC and act by indirectly blocking replicative forks. However, these drugs are not highly effective at suppressing disease progression, indicating a need for the development of innovative therapeutic approaches. Recent studies indicate that suppression of the MCM helicase may provide a novel means to sensitize cancer cells to chemotherapeutic agents that inhibit replicative fork progression. Mammalian cells assemble more MCM complexes on DNA than are required to start S-phase. The excess MCM complexes function as back-up initiation sites under conditions of replicative stress. The current study provides definitive evidence that co-suppression of the excess/back-up MCM complexes sensitizes PDAC tumor lines to both gemcitabine and 5-FU, leading to increased loss of proliferative capacity compared to drugs alone. This occurs because reduced MCM levels prevent efficient recovery of DNA replication in tumor cells exposed to drug. PDAC tumor cells are more sensitive to MCM loss in the presence of gemcitabine than are non-tumor, immortalized epithelial cells. Similarly, colon tumor cells are rendered less viable when co-suppression of MCM complexes occurs during exposure to the crosslinking agent oxaliplatin or topoisomerase inhibitor etoposide. Implications These studies demonstrate that suppressing the back-up complement of MCM complexes provides an effective sensitizing approach with the potential to increase the therapeutic index of drugs used in the clinical management of PDAC and other cancers. PMID:26063742

Suppression of Reserve MCM Complexes Chemosensitizes to Gemcitabine and 5-Fluorouracil.

PubMed

Bryant, Victoria L; Elias, Roy M; McCarthy, Susan M; Yeatman, Timothy J; Alexandrow, Mark G

2015-09-01

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest forms of cancer and is very difficult to treat with conventional chemotherapeutic regimens. Gemcitabine and 5-fluorouracil are used in the management of PDAC and act by indirectly blocking replicative forks. However, these drugs are not highly effective at suppressing disease progression, indicating a need for the development of innovative therapeutic approaches. Recent studies indicate that suppression of the MCM helicase may provide a novel means to sensitize cancer cells to chemotherapeutic agents that inhibit replicative fork progression. Mammalian cells assemble more MCM complexes on DNA than are required to start S-phase. The excess MCM complexes function as backup initiation sites under conditions of replicative stress. The current study provides definitive evidence that cosuppression of the excess/backup MCM complexes sensitizes PDAC tumor lines to both gemcitabine and 5-FU, leading to increased loss of proliferative capacity compared with drugs alone. This occurs because reduced MCM levels prevent efficient recovery of DNA replication in tumor cells exposed to drug. PDAC tumor cells are more sensitive to MCM loss in the presence of gemcitabine than are nontumor, immortalized epithelial cells. Similarly, colon tumor cells are rendered less viable when cosuppression of MCM complexes occurs during exposure to the crosslinking agent oxaliplatin or topoisomerase inhibitor etoposide. These studies demonstrate that suppressing the backup complement of MCM complexes provides an effective sensitizing approach with the potential to increase the therapeutic index of drugs used in the clinical management of PDAC and other cancers. ©2015 American Association for Cancer Research.

How MCM loading and spreading specify eukaryotic DNA replication initiation sites

PubMed Central

Hyrien, Olivier

2016-01-01

DNA replication origins strikingly differ between eukaryotic species and cell types. Origins are localized and can be highly efficient in budding yeast, are randomly located in early fly and frog embryos, which do not transcribe their genomes, and are clustered in broad (10-100 kb) non-transcribed zones, frequently abutting transcribed genes, in mammalian cells. Nonetheless, in all cases, origins are established during the G1-phase of the cell cycle by the loading of double hexamers of the Mcm 2-7 proteins (MCM DHs), the core of the replicative helicase. MCM DH activation in S-phase leads to origin unwinding, polymerase recruitment, and initiation of bidirectional DNA synthesis. Although MCM DHs are initially loaded at sites defined by the binding of the origin recognition complex (ORC), they ultimately bind chromatin in much greater numbers than ORC and only a fraction are activated in any one S-phase. Data suggest that the multiplicity and functional redundancy of MCM DHs provide robustness to the replication process and affect replication time and that MCM DHs can slide along the DNA and spread over large distances around the ORC. Recent studies further show that MCM DHs are displaced along the DNA by collision with transcription complexes but remain functional for initiation after displacement. Therefore, eukaryotic DNA replication relies on intrinsically mobile and flexible origins, a strategy fundamentally different from bacteria but conserved from yeast to human. These properties of MCM DHs likely contribute to the establishment of broad, intergenic replication initiation zones in higher eukaryotes. PMID:27635237

Adsorption of toxic metal ion Cr(VI) from aqueous state by TiO2-MCM-41: equilibrium and kinetic studies.

PubMed

Parida, Kulamani; Mishra, Krushna Gopal; Dash, Suresh Kumar

2012-11-30

This paper deals with the immobilization of various weight percentage of TiO(2) on mesoporous MCM-41, characterization of the materials by X-ray diffraction (XRD), nitrogen adsorption-desorption, Fourier Transform Infrared (FTIR) analysis, UV-vis diffuse reflectance spectroscopy (DRS) and evaluation of the adsorption capacity toward Cr(VI) removal. It is found that the MCM-41 structure retained after loading of TiO(2) but the surface area and pore diameter decreased due to pore blockage. Adsorption of Cr(VI) from aqueous state was investigated on TiO(2)-MCM-41 by changing various parameters such as pH, metal ion concentration, and the temperature. When TiO(2) loading was more than 20 wt.%, the adsorption activity (25)TiO(2)-MCM-41 reduced significantly due to considerable decrease in the surface area. It is also observed that TiO(2) and neat MCM-41 exhibits very less Cr(VI) adsorption compared to TiO(2)-MCM-41. The adsorption of Cr(VI) onto (20)TiO(2)-MCM-41 at pH~5.5 and temperature 323 K was 91% at 100mg/L Cr(VI) metal ion concentration in 80 min. The experimental data fitted well to Langmuir and Freundlich isotherms. The adsorption of Cr(VI) on TiO(2)-MCM-41 followed a second order kinetics with higher values of intra-particle diffusion rate. Thermodynamic parameters suggested that the adsorption process is endothermic in nature and desorption studies indicated a chemisorption mode. Copyright © 2012 Elsevier B.V. All rights reserved.

Murine maternal cell microchimerism: analysis using real-time PCR and in vivo imaging1

PubMed Central

Su, Eric C.; Johnson, Kirby L.; Tighiouart, Hocine; Bianchi, Diana W.

2009-01-01

In humans, maternal cells are present in the affected tissues of children with inflammatory myopathy, scleroderma, and neonatal lupus. It is unknown if maternal cell microchimerism (MCM) contributes to the pathology of disease. We sought to understand the factors that affect MCM to serve as a baseline for future mechanistic studies. Using a mouse model, we bred female mice transgenic for the luciferase (Luc) reporter gene to wild type (WT) males. The WT offspring were sacrificed at various postnatal ages. DNA was extracted from multiple organs and real-time PCR amplification was used to quantify Luc transgene as a marker for maternally derived cells. Sensitivity was 1 to 2 transgenic cells per 100,000 WT cells. MCM was noted in 85% of mice and 45% of tissues assayed. The average quantity of MCM was 158 maternal cells per 100,000 neonatal cells. The organs displaying the highest frequency and quantity of MCM were heart and lung (p<0.001). Postnatal age up to 21 days did not appear to affect levels of MCM (p=0.47), whereas increasing parity may increase levels of MCM. The data show that MCM is a common occurrence in healthy newborn mice, is present in their major organs, and that there are organ specific differences. This may represent differential migration of maternal cells, or varying receptivity of specific fetal organs to microchimerism. Pregnancy history appears to play a role in maternal cell trafficking. The role of MCM in pregnancy and disease pathogenesis remains to be elucidated. PMID:18256332

Performance of Zn-Fe-Mn/MCM-48 sorbents for high temperature H2S removal and analysis of regeneration process

NASA Astrophysics Data System (ADS)

Huang, Z. B.; Liu, B. S.; Wang, F.; Amin, R.

2015-10-01

MCM-48 was synthesized using a rapid and facile process at room temperature. A series of 50%Zn-Fe-Mn/MCM-48 sorbents were prepared and their performance of hot coal gas desulfurization was investigated. High breakthrough sulfur capacity (13.2 g-S/100 g sorbent) and utilization (66.1%) of 50%1Zn2Fe2Mn/MCM-48 sorbent at 550 °C was achieved. The characterization results of XRD, BET, TPR and FT-IR revealed that MCM-48 had excellent thermal stability at less than 700 °C, ZnMn2O4 and (Mn, Zn)Fe2O4 were mainly active particles in fresh sorbents which were highly dispersed on support. The MCM-48 mesoporous structure remained intact after eight successive desulfurization/regeneration cycles. The regeneration process of 50%1Zn2Fe2Mn/MCM-48 sorbent was analyzed, it indicated that the breakthrough sulfur capacity decline of sorbent was due to the migration of Zn onto the sorbent surface and Zn accumulated on the surface and vaporized to the exterior from the surface. In the TPO test, the oxidation of Zn was different for 50%Zn/MCM-48 at 700 °C. It revealed that the temperature of regeneration for ZnO sorbent should be higher than 700 °C.

HPV-type-specific response of cervical cancer cells to cisplatin after silencing replication licensing factor MCM4.

PubMed

Das, Mitali; Prasad, Shyam Babu; Yadav, Suresh Singh; Modi, Arusha; Singh, Sunita; Pradhan, Satyajit; Narayan, Gopeshwar

2015-12-01

Minichoromosome maintenance (MCM) proteins play key role in cell cycle progression by licensing DNA replication only once per cell cycle. These proteins are found to be overexpressed in cervical cancer cells. In this study, we depleted MCM4, one of the MCM 2-7 complex components by RNA interference (RNAi) in four cervical cancer cell lines. The four cell lines were selected on the basis of their human papillomavirus (HPV) infection: HPV16-positive SiHa, HPV18-positive ME-180, HPV16- and HPV18-positive CaSki, and HPV-negative C-33A. The MCM4-deficient cells irrespective of their HPV status grow for several generations and maintain regular cell cycle. We did not find any evidence of augmented response to a short-term (48 h) cisplatin treatment in these MCM4-deficient cells. However, MCM4-/HPV16+ SiHa cells cannot withstand a prolonged treatment (up to 5 days) of even a sublethal dosage of cisplatin. They show increased chromosomal instability compared to their control counterparts. On the other hand, MCM4-deficient CaSki cells (both HPV16+ and 18+) remain resistant to a prolonged exposure to cisplatin. Our study indicates that cervical cancer cells may be using excess MCMs as a backup for replicative stress; however, its regulatory mechanism is dependent on the HPV status of the cells.

MCM-41 impregnated with A zeolite precursor: Synthesis, characterization and tetracycline antibiotics removal from aqueous solution

PubMed Central

Liu, Minmin; Hou, Li-an; Yu, Shuili; Xi, Beidou; Zhao, Ying; Xia, Xunfeng

2013-01-01

In this paper, the MCM-41 has been modified by impregnation with zeolite A to prepare a kind of new adsorbent. The adsorption of TC from aqueous solutions onto modified MCM-41 has been studied. It was discovered that the adsorption capability of zeolite A modified MCM-41 (A-MCM-41) increased dramatically after modification. The modified MCM-41 was characterized by X-ray diffraction (XRD), nitrogen adsorption–desorption, Fourier Transform Infrared (FTIR) analysis, Transmission electron microscopy (TEM) images, and 29Si and 27Al Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) spectra. The modified MCM-41 structure was still retained after impregnated with zeolite A but the surface area and pore diameter decreased due to pore blockage. The adsorption of TC on modified MCM-41 was discussed regarding various parameters such as pH, initial TC concentration, and the reaction time. The pH effects on TC adsorption indicated that the adsorbents had better adsorption performances in acidic and neutral conditions. The adsorption isotherms were fitted well by the Langmuir model. The adsorption kinetics was well described by both pseudo-second order equation and the intra-particle diffusion model. The adsorption behavior in a fixed-bed column system followed Thomas model. The adsorption behavior of TC was the chemical adsorption with an ion exchange process and electrostatic adsorption. PMID:24976787

Pore radius fine tuning of a silica matrix (MCM-41) based on the synthesis of alumina nanolayers with different thicknesses by atomic layer deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zemtsova, Elena G., E-mail: ezimtsova@yandex.ru; Arbenin, Andrei Yu.; Plotnikov, Alexander F.

2015-03-15

The authors investigated a new approach to modify the surface of the mesoporous silica matrix MCM-41. This approach is based on manipulating the chemical composition of the porous surface layer and also on fine tuning the pore radius by applying the atomic layer deposition (ALD) technique. The synthesis of alumina nanolayers was performed on the planar and the porous matrix (MCM-41) by the ALD technique using aluminum tri-sec-butoxide and water as precursors. The authors show that one cycle on silicon, using aluminum tri-sec-butoxide and water as precursors, results in a 1–1.2 Å increase in alumina nanolayer thickness. This is comparable tomore » the increase in thickness per cycle for other precursors such as trimethylaluminum and aluminum chloride. The authors show that the synthesis of an Al{sub 2}O{sub 3} nanolayer on the pore surface of the mesoporous silica matrix MCM-41 by the ALD technique results in a regular change in the porous structure of the samples. The specific porosity (ml/g) of the MCM-41 was 0.95 and that of MCM-41 after 5 ALD cycles was 0.39. The pore diameter (nm) of MCM-41 was 3.3 and that of MCM-41 after 5 ALD cycles was 2.3.« less

Prognostic significance of MCM 2 and Ki-67 in neuroblastic tumors in children.

PubMed

Lewandowska, Magdalena; Taran, Katarzyna; Sitkiewicz, Anna; Andrzejewska, Ewa

2015-12-02

Neuroblastic tumors can be characterized by three features: spontaneous regression, maturation and aggressive proliferation. The most common and routinely used method of assessing tumor cell proliferation is to determine the Ki-67 index in the tumor tissue. Despite numerous studies, neuroblastoma biology is not fully understood, which makes treatment results unsatisfactory. MCM 2 is a potential prognostic factor in the neuroblastoma group. The study is based on retrospective analysis of 35 patients treated for neuroblastic tumors in the Department of Pediatric Surgery and Oncology of the Medical University of Lodz, during the period 2001-2011. The material comprised tissues of 16 tumors excised during the operation and 19 biopsy specimens. Immunohistochemical examinations were performed with immunoperoxidase using mouse monoclonal anti-MCM 2 and anti-Ki-67 antibodies. We observed that MCM 2 expression ranged from 2% to 98% and the Ki-67 index ranged from 0 to 95%. There was a statistically significant correlation between expression of MCM 2 and the value of the Ki-67 index and a correlation close to statistical significance between expression of MCM 2 and unfavorable histopathology. There was no statistical relationship between expression of MCM 2 and age over 1 year and N-myc amplification. The presented research shows that MCM 2 may have prognostic significance in neuroblastic pediatric tumors and as a potential prognostic factor could be the starting point of new individualized therapy.

MCM-41 impregnated with A zeolite precursor: Synthesis, characterization and tetracycline antibiotics removal from aqueous solution.

PubMed

Liu, Minmin; Hou, Li-An; Yu, Shuili; Xi, Beidou; Zhao, Ying; Xia, Xunfeng

2013-05-01

In this paper, the MCM-41 has been modified by impregnation with zeolite A to prepare a kind of new adsorbent. The adsorption of TC from aqueous solutions onto modified MCM-41 has been studied. It was discovered that the adsorption capability of zeolite A modified MCM-41 (A-MCM-41) increased dramatically after modification. The modified MCM-41 was characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, Fourier Transform Infrared (FTIR) analysis, Transmission electron microscopy (TEM) images, and 29 Si and 27 Al Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) spectra. The modified MCM-41 structure was still retained after impregnated with zeolite A but the surface area and pore diameter decreased due to pore blockage. The adsorption of TC on modified MCM-41 was discussed regarding various parameters such as pH, initial TC concentration, and the reaction time. The pH effects on TC adsorption indicated that the adsorbents had better adsorption performances in acidic and neutral conditions. The adsorption isotherms were fitted well by the Langmuir model. The adsorption kinetics was well described by both pseudo-second order equation and the intra-particle diffusion model. The adsorption behavior in a fixed-bed column system followed Thomas model. The adsorption behavior of TC was the chemical adsorption with an ion exchange process and electrostatic adsorption.

Synthesis and Characterization of Chlorpyrifos/Copper(II) Schiff Base Mesoporous Silica with pH Sensitivity for Pesticide Sustained Release.

PubMed

Chen, Huayao; Lin, Yueshun; Zhou, Hongjun; Zhou, Xinhua; Gong, Sheng; Xu, Hua

2016-11-02

The salicylaldehyde-modified mesoporous silica (SA-MCM-41) was prepared through a co-condensation method. Through the bridge effect from the copper ion, which also acts as the nutrition of the plant, the model drug chlorpyrifos (CH) was supported on the copper(II) Schiff base mesoporous silica (Cu-MCM-41) to form a highly efficient sustained-release system (CH-Cu-MCM-41) for pesticide delivery. The experimental results showed that the larger the concentration of the copper ion, the more adsorption capacity (AC) of Cu-MCM-41 for chlorpyrifos and the smaller its release rate. The results confirmed the existence of a coordination bond between SA-MCM-41 and copper ions as well as a coordination bond between Cu-MCM-41 and chlorpyrifos. The AC of SA-MCM-41 is 106 mg/g, while that of Cu-MCM-41 is 295 mg/g. The as-synthesized system showed significant pH sensitivity. Under the condition of pH ≤ 7, the release rate of chlorpyrifos decreased with increasing pH, whereas its release rate in weak base conditions was slightly larger than that in weak acid conditions. Meanwhile, the drug release rate of the as-synthesized system was also affected by the temperature. Their sustained-release curves can be described by the Korsmeyer-Peppas equation.

Low level light therapy modulates inflammatory mediators secreted by human annulus fibrosus cells during intervertebral disc degeneration in vitro.

PubMed

Hwang, Min Ho; Shin, Jae Hee; Kim, Kyoung Soo; Yoo, Chang Min; Jo, Ga Eun; Kim, Joo Han; Choi, Hyuk

2015-01-01

Intervertebral disc degeneration (IVD) is one of the important causes of low back pain and is associated with inflammation induced by interaction between macrophages and the human annulus fibrosus (AF) cells. Low-level light therapy (LLLT) has been widely known to regulate inflammatory reaction. However, the effect of LLLT on macrophage-mediated inflammation in the AF cells has not been studied till date. The aim of this study is to mimic the inflammatory microenvironment and to investigate the anti-inflammatory effect of LLLT at a range of wavelengths (405, 532 and 650 nm) on the AF treated with macrophage-like THP-1 cells conditioned medium (MCM) containing proinflammatory cytokines and chemokines (interleukin-1beta, tumor necrosis factor-alpha, interleukin-6 and 8). We observed that AF cells exposed to MCM secrete significantly higher concentrations of IL-6, IL-8, IL-1β and TNF-α. LLLT markedly inhibited secretion of IL-6 at 405 nm in a time-dependent manner. Level of IL-8 was significantly decreased at all wavelengths in a time-dependent manner. We showed that MCM can induce the inflammatory microenvironment in AF cells and LLLT selectively suppressed IL-6 and 8 levels. The results indicate that LLLT is a potential method of IVD treatment and provide insights into further investigation of its anti-inflammation effect on IVD. © 2015 The American Society of Photobiology.

Effect of H{sub 3}PW{sub 12}O{sub 40} impregnation on Sn-MCM-41 mesoporous molecular sieves and their physico-chemical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nedumaran, D.; Department of Chemistry, RMK Engineering College, Chennai; Pandurangan, A., E-mail: pandurangan_a@yahoo.com

2015-01-15

Graphical abstract: The wide angle XRD shows the well dispersion of HPWA in Sn-MCM-41. It enhances the total acidity of the material. The acidity of the material is correlated with sulfone selectivity. The FT-IR of dibenzothiophene and product shows the formation of sulfone (DBTO{sub 2}). - Highlights: • To enhance the total acidity of Sn-MCM-41 TPA is impregnated. • FT-IR and {sup 31}P MAS NMR confirms the HPWA intact on Sn-MCM-41. • EDAX shows the presence of W and P on Sn-MCM-41. • In ODS formation of sulfone was confirmed by FT-IR and {sup 1}H NMR. • The order ofmore » the catalytic activity of the catalysts are 18HSnM > 28HSnM > 8HSnM. - Abstract: Si-Sn-MCM-41 (Si/Sn = 110) mesoporous molecular sieve was synthesized by hydrothermal sol–gel method using cetyltrimethylammonium bromide (CTAB) as surfactant and SnCl{sub 4}·5H{sub 2}O as a metal source. To generate surface acidity of Si-Sn-MCM-41, 12-tungstophosphoric acid (HPWA) is impregnated on it. The acidity of HPWA loading on Sn-MCM-41 was investigated by temperature programmed desorption of NH{sub 3}. The diffused reflectance spectra of ultraviolet radiation, Raman spectra, FT-IR, {sup 29}Si-MAS NMR and {sup 31}P-MAS NMR techniques revealed the intact of α-Keggin anions on Sn-MCM-41. The wide angle XRD results showed that the HPWA is well dispersed on the support. The total acidity was enhanced with increase in loading of H{sub 3}PW{sub 12}O{sub 40}. The catalytic activity was examined in desulfurization of dibenzothiophene in vapor phase system. Among the catalysts 18% HPWA loaded Sn-MCM-41 showed good catalytic activity in desulfurization at 325 °C. The HPWA/Sn-MCM-41 are a suitable solid acid catalyst for converting organic sulfur into insoluble sulfone.« less

Inflammatory stimuli promote growth and invasion of pancreatic cancer cells through NF-κB pathway dependent repression of PP2Ac

PubMed Central

Tao, Min; Liu, Lu; Shen, Meng; Zhi, Qiaoming; Gong, Fei-Ran; Zhou, Binhua P.; Wu, Yadi; Liu, Haiyan; Chen, Kai; Shen, Bairong; Wu, Meng-Yao; Shou, Liu-Mei; Li, Wei

2016-01-01

ABSTRACT Previous studies have indicated that inflammatory stimulation represses protein phosphatase 2A (PP2A), a well-known tumor suppressor. However, whether PP2A repression participates in pancreatic cancer progression has not been verified. We used lipopolysaccharide (LPS) and macrophage-conditioned medium (MCM) to establish in vitro inflammation models, and investigated whether inflammatory stimuli affect pancreatic cancer cell growth and invasion PP2A catalytic subunit (PP2Ac)-dependently. Via nude mouse models of orthotopic tumor xenografts and dibutyltin dichloride (DBTC)-induced chronic pancreatitis, we evaluated the effect of an inflammatory microenvironment on PP2Ac expression in vivo. We cloned the PP2Acα and PP2Acβ isoform promoters to investigate the PP2Ac transcriptional regulation mechanisms. MCM accelerated pancreatic cancer cell growth; MCM and LPS promoted cell invasion. DBTC promoted xenograft growth and metastasis, induced tumor-associated macrophage infiltration, promoted angiogenesis, activated the nuclear factor-κB (NF-κB) pathway, and repressed PP2Ac expression. In vitro, LPS and MCM downregulated PP2Ac mRNA and protein. PP2Acα overexpression attenuated JNK, ERK, PKC, and IKK phosphorylation, and impaired LPS/MCM-stimulated cell invasion and MCM-promoted cell growth. LPS and MCM activated the NF-κB pathway in vitro. LPS and MCM induced IKK and IκB phosphorylation, leading to p65/RelA nuclear translocation and transcriptional activation. Overexpression of the dominant negative forms of IKKα attenuated LPS and MCM downregulation of PP2Ac, suggesting inflammatory stimuli repress PP2Ac expression NF-κB pathway–dependently. Luciferase reporter gene assay verified that LPS and MCM downregulated PP2Ac transcription through an NF-κB–dependent pathway. Our study presents a new mechanism in inflammation-driven cancer progression through NF-κB pathway–dependent PP2Ac repression. PMID:26761431

Enhanced adsorptive and photocatalytic achievements in removal of methylene blue by incorporating tungstophosphoric acid-TiO2 into MCM-41.

PubMed

Zanjanchi, M A; Golmojdeh, H; Arvand, M

2009-09-30

The use of titania-dispersed materials in photocatalytic processes has been proposed as an alternative to the conventional bare TiO(2), in order to modify the surface area and activity of the catalyst. A homogeneously dispersed Keggin unit into TiO(2) was synthesized using tungstophosphoric acid (TPA) and titanium tetraisopropoxide. This compound was then loaded into MCM-41 by dispersing it in a suspension containing the mesoporous phase. Two other titanium-containing MCM-41 catalysts, Ti-MCM-41 and TiO(2)/MCM-41 were also prepared using isomorphous substitution synthesis method and impregnation method, respectively, for the sake of comparison. The prepared photocatalysts were characterized by X-ray diffraction (XRD), nitrogen physisorption (BET) and chemical analysis. The catalysts were used to study degradation of methylene blue (MB) in aqueous solution. XRD result shows a pure anatase crystalline phase for TPA-containing TiO(2) indicating that there is good molecular distribution of tungstophosphoric acid into TiO(2) structure. Supported TPA-TiO(2) into MCM-41 shows both TPA-TiO(2) and MCM-41 characteristic X-ray reflections in the high-angle and low-angle parts of the XRD patterns, respectively. The experimental results show that adsorption is a major constituent in the elimination of MB from the dye solutions by the TPA-containing materials. Exploitation of both adsorption and photocatalytic processes speeds up the removal of the dye using the TPA-TiO(2)-loaded MCM-41 photocatalyst. The elimination of MB is completed within 15 min for a 30 mg l(-1) MB solution containing a catalyst dose of 100mg/100ml. The efficiencies of the other photocatalysts such as commercial TiO(2), Ti-MCM-41, TiO(2)/MCM-41 and TPA-TiO(2) for adsorption and degradation of MB were also studied and compared with that of the prepared catalyst.

pH-insusceptible cobalt-manganese immobilizing mesoporous siliceous MCM-41 catalyst for ozonation of dimethyl phthalate.

PubMed

Tang, Yiming; Pan, Zhaoqi; Li, Laisheng

2017-12-15

Mesoporous siliceous MCM-41 immobilized with Co and Mn metal ions (Co-Mn-MCM-41) was synthesized using a hydrothermal method. The structural regularity and the valence states of the metal species were measured by X-ray diffractometer and X-ray photoelectron spectrometer. The resultant bimetallic Co-Mn-MCM-41 catalyst was tested for the degradation of dimethyl phthalate (DMP) via a catalytic ozonation mechanism, demonstrating that the catalytic properties of Co-Mn-MCM-41 catalyst significantly accelerated the ozonation process. Total organic carbon (TOC) and DMP removal efficiency reached 94% and 99.7% at 15min under the optimal conditions. The oxidation pathways were proposed after identifying the intermediate products from ozonation using a gas chromatography-mass spectrometer. The enhanced catalytic reactivity was attributed to the highly-dispersive cobalt and manganese species in MCM-41 scaffolds, which promoted the ozone decomposition and hydroxyl radicals' generation in catalytic ozonation and accelerated the degradation of DMP. Bimetallic Co-Mn-MCM-41 catalyst remained stable in mild acidic conditions and continued to show high activity after repeated runs. Copyright © 2017 Elsevier Inc. All rights reserved.

The MCM Helicase Motor of the Eukaryotic Replisome.

PubMed

Abid Ali, Ferdos; Costa, Alessandro

2016-05-08

The MCM motor of the CMG helicase powers ahead of the eukaryotic replication machinery to unwind DNA, in a process that requires ATP hydrolysis. The reconstitution of DNA replication in vitro has established the succession of events that lead to replication origin activation by the MCM and recent studies have started to elucidate the structural basis of duplex DNA unwinding. Despite the exciting progress, how the MCM translocates on DNA remains a matter of debate. Copyright © 2016. Published by Elsevier Ltd.

Concerted activities of Mcm4, Sld3, and Dbf4 in control of origin activation and DNA replication fork progression

PubMed Central

Sheu, Yi-Jun; Kinney, Justin B.; Stillman, Bruce

2016-01-01

Eukaryotic chromosomes initiate DNA synthesis from multiple replication origins in a temporally specific manner during S phase. The replicative helicase Mcm2-7 functions in both initiation and fork progression and thus is an important target of regulation. Mcm4, a helicase subunit, possesses an unstructured regulatory domain that mediates control from multiple kinase signaling pathways, including the Dbf4-dependent Cdc7 kinase (DDK). Following replication stress in S phase, Dbf4 and Sld3, an initiation factor and essential target of Cyclin-Dependent Kinase (CDK), are targets of the checkpoint kinase Rad53 for inhibition of initiation from origins that have yet to be activated, so-called late origins. Here, whole-genome DNA replication profile analysis is used to access under various conditions the effect of mutations that alter the Mcm4 regulatory domain and the Rad53 targets, Sld3 and Dbf4. Late origin firing occurs under genotoxic stress when the controls on Mcm4, Sld3, and Dbf4 are simultaneously eliminated. The regulatory domain of Mcm4 plays an important role in the timing of late origin firing, both in an unperturbed S phase and in dNTP limitation. Furthermore, checkpoint control of Sld3 impacts fork progression under replication stress. This effect is parallel to the role of the Mcm4 regulatory domain in monitoring fork progression. Hypomorph mutations in sld3 are suppressed by a mcm4 regulatory domain mutation. Thus, in response to cellular conditions, the functions executed by Sld3, Dbf4, and the regulatory domain of Mcm4 intersect to control origin firing and replication fork progression, thereby ensuring genome stability. PMID:26733669

Amino-functionalized mesoporous MCM-41 silica as an efficient adsorbent for water treatment: batch and fixed-bed column adsorption of the nitrate anion

NASA Astrophysics Data System (ADS)

Ebrahimi-Gatkash, Mehdi; Younesi, Habibollah; Shahbazi, Afsaneh; Heidari, Ava

2017-07-01

In the present study, amino-functionalized Mobil Composite Material No. 41 (MCM-41) was used as an adsorbent to remove nitrate anions from aqueous solutions. Mono-, di- and tri-amino functioned silicas (N-MCM-41, NN-MCM-41 and NNN-MCM-41) were prepared by post-synthesis grafting method. The samples were characterized by means of X-ray powder diffraction, FTIR spectroscopy, thermogravimetric analysis, scanning electron microscopy and nitrogen adsorption-desorption. The effects of pH, initial concentration of anions, and adsorbent loading were examined in batch adsorption system. Results of adsorption experiments showed that the adsorption capacity increased with increasing adsorbent loading and initial anion concentration. It was found that the Langmuir mathematical model indicated better fit to the experimental data than the Freundlich. According to the constants of the Langmuir equation, the maximum adsorption capacity for nitrate anion by N-MCM-41, NN-MCM-41 and NNN-MCM-41 was found to be 31.68, 38.58 and 36.81 mg/g, respectively. The adsorption kinetics were investigated with pseudo-first-order and pseudo-second-order model. Adsorption followed the pseudo-second-order rate kinetics. The coefficients of determination for pseudo-second-order kinetic model are >0.99. For continuous adsorption experiments, NNN-MCM-41 adsorbent was used for the removal of nitrate anion from solutions. Breakthrough curves were investigated at different bed heights, flow rates and initial nitrate anion concentrations. The Thomas and Yan models were utilized to calculate the kinetic parameters and to predict the breakthrough curves of different bed height. Results from this study illustrated the potential utility of these adsorbents for nitrate removal from water solution.

Catalytic co-pyrolysis of cellulose and polypropylene over all-silica mesoporous catalyst MCM-41 and Al-MCM-41.

PubMed

Chi, Yongchao; Xue, Junjie; Zhuo, Jiankun; Zhang, Dahu; Liu, Mi; Yao, Qiang

2018-08-15

Fast pyrolysis is one of the most economical and efficient technologies to convert biomass to bio-oil and valuable chemical products. Co-pyrolysis with hydrogen rich materials such as plastics over zeolite catalysts is one of the significant solutions to various problems of bio-oil such as high oxygen content, low heat value and high acid content. This paper studied pyrolysis of cellulose and polypropylene (PP) separately and co-pyrolysis of cellulose and PP over MCM-41 and Al-MCM-41. The pyrolysis over different heating rates (10K/min, 20K/min, 30K/min) was studied by Thermogravimetry Analysis (TGA) and kinetic parameters were obtained by Coats-Redfern method and isoconversion method. TG and DTG data shows that the two catalysts advance the pyrolysis reaction of PP significantly and reduce its peak temperature of DTG curve from 458°C to 341°C. The activation energy of pyrolysis of PP also has a remarkable reduction over the two catalysts. Py-GC/MS method was used to obtain the product distribution of pyrolysis of cellulose and PP separately and co-pyrolysis of cellulose and PP over MCM-41 and Al-MCM-41 at constant temperature of 650°C. Experiment results proved that co-pyrolysis with PP bring significant changes to the product distribution of cellulose. Oxygenated compounds such as furans are decreased, while yields of olefins and aromatics increase greatly. The yield of furans increases with the catalysis of MCM-41 as for the pyrolysis of cellulose and co-pyrolysis, while the yield of olefins and aromatics both experience significant growth over Al-MCM-41, which can be explained by the abundant acid centers in Al-MCM-41. Copyright © 2018 Elsevier B.V. All rights reserved.

Preparation and Humidity Sensing Properties of KCl/MCM-41 Composite

NASA Astrophysics Data System (ADS)

Liu, Li; Kou, Li-Ying; Zhong, Zhi-Cheng; Wang, Lian-Yuan; Liu, Li-Fang; Li, Wei

2010-05-01

KCl/mobil composition of matter-41 (MCM-41) composite has been synthesized via a heat-treating process and characterized by x-ray diffraction, high resolution transmission electron microscopy, and nitrogen adsorption/desorption isotherms. In contrast with pure MCM-41, KCl/MCM-41 composite exhibits improved humidity sensing properties within the relative humidity range of 11-95%. The impedance of KCl/MCM-41 composite changes by about four orders of magnitude over the whole humidity range with the response time and the recovery times are about 30 s and 35 s, respectively. Small humidity hysteresis and good stability are also observed based on our product. These results make our product a good candidate in fabricating humidity sensors with high performances and low synthetic complexity.

Molecular simulation of fluid adsorption in buckytubes and MCM-41

NASA Astrophysics Data System (ADS)

Maddox, M. W.; Gubbins, K. E.

1994-11-01

We report grand canonical Monte Carlo (GCMC) molecular-simulation studies of argon and nitrogen in models of two novel adsorbents, buckytubes and MCM-41. Buckytubes are monodisperse carbon tubes with internal diameters of 1 5 nm and a regular pore structure. MCM-41 is one member of a new family of highly uniform mesoporous aluminosilicates produced by Mobil. The pore size of MCM-41 can be accurately controlled within the range 1.5-I.0 nm. The adsorption of argon in a buckytube and the adsorption of nitrogen in two different MCM-41 pores are studied at 77 K. Both fluids are modeled as Lennard-Jones spheres. and an averaged fluid-wall potential, dependent only on the distance of the adsorbed molecule from the center of the tube or pore is used. Isotherms and isosteric heats are calculated. Layering transitions and a hysteresis loop are observed for the buckytube and good agreement is found between simulated and experimental isotherms for the MCM-41 systems.

Ce, Ti modified MCM-48 mesoporous photocatalysts: Effect of the synthesis route on support and metal ion properties

NASA Astrophysics Data System (ADS)

Mureseanu, Mihaela; Filip, Mihaela; Somacescu, Simona; Baran, Adriana; Carja, Gabriela; Parvulescu, Viorica

2018-06-01

New Ti-MCM-48 and CeTi-MCM-48 photocatalysts were obtained by impregnation of the MCM-48 silica support synthesized by a hydrothermal process with aqueous solution of Ti and Ce precursors. The immobilization of metal cations presented a low effect on the porosity, morphology and structure of MCM-48 mesoporous silica support as was evidenced by N2 adsorption-desorption, X-ray diffraction, SEM and TEM electron microscopy. EDAX analysis and X-ray photoelectron microscopy (XPS) indicated that titanium cations were present on the mesoporous silica surface only as Ti4+ species and the effect of ceria on titanium speciation was different, compared to the CeTi-MCM-48 sample, previously obtained by direct synthesis. The photocatalytic properties of mono- and bimetallic catalysts were evaluated in degradation of phenol from water and correlated with the active metallic species concentration, distribution, speciation and their interaction with the support or each other. An advanced oxidation mechanism for phenol degradation by radical species was proposed.

Probing the porosity of cocrystallized MCM-49/ZSM-35 zeolites by hyperpolarized 129Xe NMR.

PubMed

Liu, Yong; Zhang, Weiping; Xie, Sujuan; Xu, Longya; Han, Xiuwen; Bao, Xinhe

2008-01-31

One- and two-dimensional 129Xe NMR spectroscopy has been employed to study the porosity of cocrystallized MCM-49/ZSM-35 zeolites under the continuous flow of hyperpolarized xenon gas. It is found by variable-temperature experiments that Xe atoms can be adsorbed in different domains of MCM-49/ZSM-35 cocrystallized zeolites and the mechanically mixed counterparts. The exchange of Xe atoms in different types of pores is very fast at ambient temperatures. Even at very low temperature two-dimensional exchange spectra (EXSY) show that Xe atoms still undergo much faster exchange between MCM-49 and ZSM-35 analogues in the cocrystallized zeolites than in the mechanical mixture. This demonstrates that the MCM-49 and ZSM-35 analogues in cocrystallized zeolites may be stacked much closer than in the physical mixture, and some parts of intergrowth may be formed due to the partially similar basic structure of MCM-49 and ZSM-35.

Tailoring MCM-41 mesoporous silica particles through modified sol-gel process for gas separation

NASA Astrophysics Data System (ADS)

Sang, Wong Yean; Ching, Oh Pei

2017-10-01

Mobil Composition of Matter-41 (MCM-41) is recognized as a potential filler to enhance permeability of mixed matrix membrane (MMM). However, the required loading for available micron-sized MCM-41 was considerably high in order to achieve desired separation performance. In this work, reduced-size MCM-41 was synthesized to minimize filler loading, improve surface modification and enhance polymer-filler compatibility during membrane fabrication. The effect of reaction condition, stirring rate and type of post-synthesis washing solution used on particle diameter of resultant MCM-41 were investigated. It was found that MCM-41 produced at room temperature condition yield particles with smaller diameter, higher specific surface area and enhanced mesopore structure. Increase of stirring rate up to 500 rpm during synthesis also reduced the particle diameter. In addition, replacing water with methanol as the post-synthesis washing solution to remove bromide ions from the precipitate was able to further reduce the particle size by inhibiting polycondensation reaction.

Origin Licensing Requires ATP Binding and Hydrolysis by the MCM Replicative Helicase

PubMed Central

Coster, Gideon; Frigola, Jordi; Beuron, Fabienne; Morris, Edward P.; Diffley, John F.X.

2014-01-01

Summary Loading of the six related Minichromosome Maintenance (MCM) proteins as head-to-head double hexamers during DNA replication origin licensing is crucial for ensuring once-per-cell-cycle DNA replication in eukaryotic cells. Assembly of these prereplicative complexes (pre-RCs) requires the Origin Recognition Complex (ORC), Cdc6, and Cdt1. ORC, Cdc6, and MCM are members of the AAA+ family of ATPases, and pre-RC assembly requires ATP hydrolysis. Here we show that ORC and Cdc6 mutants defective in ATP hydrolysis are competent for origin licensing. However, ATP hydrolysis by Cdc6 is required to release nonproductive licensing intermediates. We show that ATP binding stabilizes the wild-type MCM hexamer. Moreover, by analyzing MCM containing mutant subunits, we show that ATP binding and hydrolysis by MCM are required for Cdt1 release and double hexamer formation. This work alters our view of how ATP is used by licensing factors to assemble pre-RCs. PMID:25087873

Immobilization induced molecular compression of ionic liquid in ordered mesoporous matrix

NASA Astrophysics Data System (ADS)

Tripathi, Alok Kumar; Singh, Rajendra Kumar

2018-02-01

In this work, ionic liquid (IL) 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide ([EMIM][FSI]) has been immobilized into ordered mesoporous silica MCM-41 by a physical imbibition process. Transmission electron microscopy confirms the filling of mesopores of MCM-41. The effect of IL content in MCM-41 was probed in terms of thermal stability, chemical interactions, and dielectric properties. N2-sorption results indicate the compression of the IL in the nanopores of MCM-41, which contributes to an increase of the melting point probed by differential scanning calorimetry. The quantum chemical calculations confirmed that the ion-ion interaction in ion-pairs of IL were preferred over the hydrogen bonding interaction in the presence of SiO2 molecules, and these interactions probably compress the molecular size in the nanopores of MCM-41. Strong interactions between IL and porous MCM-41 were suggested as the mechanism of this immobilization, which was characterized by FTIR and dielectric spectroscopy.

Immunohistochemical Expression of MCM-2 in Oral Epithelial Dysplasias.

PubMed

Zakaria, Samar H; Farag, Heba A; Khater, Dina S

2016-03-17

Oral cancer is one of the most frequent cancers in the world. It arises from epithelial dysplasia. Hence, identifying these lesions in an early stage could prevent their malignant transformation. The aim of the present work was to assess the cell proliferative activity of minichromosome maintenance protein (MCM-2) in oral epithelial dysplastic lesions and to correlate the results with different grades of epithelial dysplasia in an attempt to use MCM-2 in the early detection of malignancy. MCM-2 expression was determined by the nuclear count in a total of 30 oral epithelial dysplastic specimens roughly classified into 10 cases of mild, moderate, and severe dysplasia. Five cases of early invasive squamous-cell carcinomas and 5 cases of epithelial hyperplasia were also included. The MCM-2 immunostaining was found to increase gradually from mild to moderate to severe dysplasia and reached its maximum value in early invasive squamous cell carcinoma. MCM-2 is of prognostic value in cases of oral dysplasia that have a tendency to undergo malignant transformation.

The Mathematical Contest in Modeling: Success at a Small Regional University.

ERIC Educational Resources Information Center

Parker, Mark; Zullo, Holly; Preyer, Norris

1999-01-01

Describes the Mathematical Contest in Modeling (MCM), a contest in which teams of three undergraduate students compete with other undergraduate teams from schools all over the world. Implements MCM at Eastern Oregon University and indicates that the MCM program promotes teamwork and generates enthusiasm in students. (Author/ASK)

Hydroxyapatite/MCM-41 and SBA-15 Nano-Composites: Preparation, Characterization and Applications

PubMed Central

Anunziata, Oscar A.; Martínez, Maria L.; Beltramone, Andrea R.

2009-01-01

Composites of hydroxyapatite (HaP) and highly ordered large pore mesoporous silica molecular sieves such as, Al-SBA-15 and Al-MCM-41 (denoted as SBA-15 and MCM-41, respectively) were developed, characterized by XRD, BET, FTIR, HRTEM and NMR-MAS, and applied to fluoride retention from contaminated water. The proposed procedure by a new route to prepare the HaP/SBA-15 and HaP/MCM-41, composites generates materials with aluminum only in tetrahedral coordination, according to the 27Al NMR-MAS results. Free OH- groups of HaP nanocrystals, within the hosts, allowed high capacity fluoride retention. The activity of fluoride retention using HaP/MCM-41 or HaP/SBA-15 was 1-2 orders of magnitude greater, respectively, than with pure HaP.

Photocatalytic degradation of tetracycline by Ti-MCM-41 prepared at room temperature and biotoxicity of degradation products

NASA Astrophysics Data System (ADS)

Zhou, Kefu; Xie, Xiao-Dan; Chang, Chang-Tang

2017-09-01

Ti-doped MCM-41 with different Si/Ti molar ratios was prepared at room temperature to degrade tetracycline antibiotics in aqueous solution. The Ti was doped into the skeleton structure of MCM-41. The photocatalytic activity of Ti-doped MCM-41 was investigated. The optimal catalyst had Si/Ti molar ratio of 25 and over 99% removal of oxytetracycline in 150 min, and the removal could maintain 98% after 5 reuses. Ions and soluble organic matters in natural water affected the degradation reaction when Ti-doped MCM-41 was used to treat simulated wastewater of chicken farms. The degradation products of oxytetracycline, tetracycline and chlortetracycline were detected by Escherichia coli DH5α and HPLC-MS/MS. No intermediate product with higher toxicity was detected.

Phosphorylation of Minichromosome Maintenance 3 (MCM3) by Checkpoint Kinase 1 (Chk1) Negatively Regulates DNA Replication and Checkpoint Activation.

PubMed

Han, Xiangzi; Mayca Pozo, Franklin; Wisotsky, Jacob N; Wang, Benlian; Jacobberger, James W; Zhang, Youwei

2015-05-08

Mechanisms controlling DNA replication and replication checkpoint are critical for the maintenance of genome stability and the prevention or treatment of human cancers. Checkpoint kinase 1 (Chk1) is a key effector protein kinase that regulates the DNA damage response and replication checkpoint. The heterohexameric minichromosome maintenance (MCM) complex is the core component of mammalian DNA helicase and has been implicated in replication checkpoint activation. Here we report that Chk1 phosphorylates the MCM3 subunit of the MCM complex at Ser-205 under normal growth conditions. Mutating the Ser-205 of MCM3 to Ala increased the length of DNA replication track and shortened the S phase duration, indicating that Ser-205 phosphorylation negatively controls normal DNA replication. Upon replicative stress treatment, the inhibitory phosphorylation of MCM3 at Ser-205 was reduced, and this reduction was accompanied with the generation of single strand DNA, the key platform for ataxia telangiectasia mutated and Rad3-related (ATR) activation. As a result, the replication checkpoint is activated. Together, these data provide significant insights into the regulation of both normal DNA replication and replication checkpoint activation through the novel phosphorylation of MCM3 by Chk1. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Steam-assisted crystallization of TPA{sup +}-exchanged MCM-41 type mesoporous materials with thick pore walls

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Hong Li; Zhang, Kun; Wang, Yi Meng, E-mail: ymwang@chem.ecnu.edu.cn

2012-07-15

Highlights: ► Mesoporous Ti-containing silica with thicker pore walls was synthesized. ► Ion-exchange and steam-assisted crystallization led to MCM-41/MFI composite. ► The introduction of Ti inhibited the formation of separated MFI particles. ► Lower temperature favored retaining mesoporous characteristics and morphology. -- Abstract: Hierarchical MCM-41/MFI composites were synthesized through ion-exchange of as-made MCM-41 type mesoporous materials with tetrapropylammonium bromide and subsequent steam-assisted recrystallization. The obtained samples were characterized by powder X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis, FT-IR, {sup 1}H–{sup 13}C CP/MAS and nitrogen adsorption–desorption. The XRD patterns show thatmore » the MCM-41/MFI composite possesses both ordered MCM-41 phase and zeolite MFI phase. SEM and TEM images indicate that the recrystallized materials retained the mesoporous characteristics and the morphology of as-made mesoporous materials without the formation of bulky zeolite, quite different from the mechanical mixture of MCM-41 and MFI structured zeolite. Among others, lower recrystallization temperature and the introduction of the titanium to the parent materials are beneficial to preserve the mesoporous structure during the recrystallization process.« less

Effect of amine functionalization of spherical MCM-41 and SBA-15 on controlled drug release

DOE Office of Scientific and Technical Information (OSTI.GOV)

Szegedi, A., E-mail: szegedi@chemres.h; Popova, M.; Goshev, I.

2011-05-15

MCM-41 and SBA-15 silica materials with spherical morphology and different particle sizes were synthesized and modified by post-synthesis method with 3-aminopropyltriethoxysilane (APTES). A comparative study of the adsorption and release of a model drug, ibuprofen, were carried out. The modified and drug loaded mesoporous materials were characterized by XRD, TEM, N{sub 2} physisorption, thermal analysis, elemental analysis and FT-IR spectroscopy. Surface modification with amino groups resulted in high degree of ibuprofen loading and slow rate of release for MCM-41, whereas it was the opposite for SBA-15. The adsorbed drug content and the delivery rate can be predetermined by the choicemore » of mesoporous material with the appropriate structural characteristics and surface functionality. -- Graphical Abstract: Ibuprofen delivery from the parent and amino-modified spherical MCM-41 materials with 100 nm (small) and 500 nm (large) particle sizes. Display Omitted Highlights: {yields} Spherical type MCM-41 and SBA-15 with different particle sizes were modified by APTES. {yields} Adsorption and release rate of ibuprofen were compared. {yields} High degree of ibuprofen loading, slow release rate for MCM-41, the opposite for SBA-15. {yields} MCM-41 with 100 nm particles was more stable and showed slower release rate« less

Surface Properties of Al-Functionalized Mesoporous MCM-41 and the Melting Behavior of Water in Al-MCM-41 Nanopores.

PubMed

Sterczyńska, Angelina; Deryło-Marczewska, Anna; Zienkiewicz-Strzałka, Małgorzata; Śliwińska-Bartkowiak, Małgorzata; Domin, Kamila

2017-10-24

We report an experimental investigation of structural and adhesive properties for Al-containing mesoporous MCM-41 and MCM-41 surfaces. In this work, highly ordered hexagonal mesoporous structures of aluminosilica with two different Si/Al molar ratios equal to 50 and 80 and silica samples were studied; Al was incorporated into the MCM-41 structures using the direct synthesis method, with CTAB as a surfactant. The incorporation of aluminum was evidenced simultaneously without any change in the hexagonal arrangement of cylindrical mesopores. The porous materials were examined by techniques such as low-temperature nitrogen sorption, energy-dispersive spectroscopy, and scanning and transmission electron microscopy. Surface properties were determined through X-ray photoelectron spectroscopy, potentiometric titration, and static contact angle measurements. It was shown that an increase in surface acidity leads to an increase in the wetting energy of the surface. To investigate the influence of acidity on the confinement effects, the melting behavior of water in Al-MCM-41 and MCM-41 with the same pore size was determined by using dielectric relaxation spectroscopy and differential scanning calorimetry methods. We found that the melting-point depression of water in pores is larger in the functionalized pores than in pure silica pores of the same pore diameter.

High acidity unilamellar zeolite MCM-56 and its pillared and delaminated derivatives.

PubMed

Gil, Barbara; Makowski, Wacław; Marszalek, Bartosz; Roth, Wieslaw J; Kubu, Martin; Čejka, Jiři; Olejniczak, Zbigniew

2014-07-21

The unilamellar form of zeolite MWW, MCM-56, which is obtained by direct hydrothermal synthesis has been studied with regard to acidity and porosity in its original and post-synthesis modified pillared and delaminated forms. The acidity measured by FTIR was found to be only slightly lower than the highly active 3-D MWW forms, MCM-22 and MCM-49. Pivalonitrile adsorption, which is a measure of spatial openness, showed 50% accessibility vs. <30% for MCM-22/49. It highlights the potential of MCM-56 as a layered material with increased access to acid sites because it does not entail laborious post-synthesis modification. Swelling, pillaring and delamination of MCM-56 are facile but result in a reduction in the number of Brønsted acid sites (BAS) while increasing accessibility to pivalonitrile. The delamination procedure involving sonication and acidification of the highly basic mother liquor produces the most visible increase in surface area and access to all BAS. The accompanying doubling of the solid yield and the decrease in absolute number of BAS suggest significant precipitation of dissolved silica generated during swelling and sonication in high pH medium. The viability of separating surfactant covered layers upon sonication with the consequence of exposing hydrophobic hydrocarbon tails to aqueous environment is addressed.

Modeling selective attention using a neuromorphic analog VLSI device.

PubMed

Indiveri, G

2000-12-01

Attentional mechanisms are required to overcome the problem of flooding a limited processing capacity system with information. They are present in biological sensory systems and can be a useful engineering tool for artificial visual systems. In this article we present a hardware model of a selective attention mechanism implemented on a very large-scale integration (VLSI) chip, using analog neuromorphic circuits. The chip exploits a spike-based representation to receive, process, and transmit signals. It can be used as a transceiver module for building multichip neuromorphic vision systems. We describe the circuits that carry out the main processing stages of the selective attention mechanism and provide experimental data for each circuit. We demonstrate the expected behavior of the model at the system level by stimulating the chip with both artificially generated control signals and signals obtained from a saliency map, computed from an image containing several salient features.

Fourier plane image amplifier

DOEpatents

Hackel, Lloyd A.; Hermann, Mark R.; Dane, C. Brent; Tiszauer, Detlev H.

1995-01-01

A solid state laser is frequency tripled to 0.3 .mu.m. A small portion of the laser is split off and generates a Stokes seed in a low power oscillator. The low power output passes through a mask with the appropriate hole pattern. Meanwhile, the bulk of the laser output is focused into a larger stimulated Brillouin scattering (SBS) amplifier. The low power beam is directed through the same cell in the opposite direction. The majority of the amplification takes place at the focus which is the fourier transform plane of the mask image. The small holes occupy large area at the focus and thus are preferentially amplified. The amplified output is now imaged onto the multichip module where the holes are drilled. Because of the fourier plane amplifier, only .about.1/10th the power of a competitive system is needed. This concept allows less expensive masks to be used in the process and requires much less laser power.

Fourier plane image amplifier

DOEpatents

Hackel, L.A.; Hermann, M.R.; Dane, C.B.; Tiszauer, D.H.

1995-12-12

A solid state laser is frequency tripled to 0.3 {micro}m. A small portion of the laser is split off and generates a Stokes seed in a low power oscillator. The low power output passes through a mask with the appropriate hole pattern. Meanwhile, the bulk of the laser output is focused into a larger stimulated Brillouin scattering (SBS) amplifier. The low power beam is directed through the same cell in the opposite direction. The majority of the amplification takes place at the focus which is the fourier transform plane of the mask image. The small holes occupy large area at the focus and thus are preferentially amplified. The amplified output is now imaged onto the multichip module where the holes are drilled. Because of the fourier plane amplifier, only about 1/10th the power of a competitive system is needed. This concept allows less expensive masks to be used in the process and requires much less laser power. 1 fig.

Experimental study on the application of paraffin slurry to high density electronic package cooling

NASA Astrophysics Data System (ADS)

Cho, K.; Choi, M.

Experiments were performed by using water and paraffin slurry to investigate thermal characteristics from a test multichip module. The parameters were the mass fraction of paraffin slurry (0, 2.5, 5, 7.5%), heat flux (10, 20, 30, 40W/cm2) and channel Reynolds numbers. The size of paraffin slurry particles was within 10-40μm. The local heat transfer coefficients for the paraffin slurry were larger than those for water. Thermally fully developed conditions were observed after the third or fourth row. The paraffin slurry with a mass fraction of 5% showed the most efficient cooling performance when the heat transfer and the pressure drop in the test section were considered simultaneously. A new correlation for the water and the paraffin slurry with a mass fraction of 5% was obtained for a channel Reynolds number over 5300.

An integrated circuit switch

NASA Technical Reports Server (NTRS)

Bonin, E. L.

1969-01-01

Multi-chip integrated circuit switch consists of a GaAs photon-emitting diode in close proximity with S1 phototransistor. A high current gain is obtained when the transistor has a high forward common-emitter current gain.

MCM2: An alternative to Ki-67 for measuring breast cancer cell proliferation.

PubMed

Yousef, Einas M; Furrer, Daniela; Laperriere, David L; Tahir, Muhammad R; Mader, Sylvie; Diorio, Caroline; Gaboury, Louis A

2017-05-01

Breast cancer is a heterogeneous disease comprising a diversity of tumor subtypes that manifest themselves in a wide variety of clinical, pathological, and molecular features. One important subset, luminal breast cancers, comprises two clinically distinct subtypes luminal A and B each of them endowed with its own genetic program of differentiation and proliferation. Luminal breast cancers were operationally defined as follows: Luminal A: ER+, PR+, HER2-, Ki-67<14% and Luminal B: ER+ and/or PR+, HER2-,Ki-67≥14% or, alternatively ER+ and/or PR+, HER2+, any Ki-67. There is currently a need for a clinically robust and validated immunohistochemical assay that can help distinguish between luminal A and B breast cancer. MCM2 is a family member of the minichromosome maintenance protein complex whose role in DNA replication and cell proliferation is firmly established. As MCM2 appears to be an attractive alternative to Ki-67, we sought to study the expression of MCM2 and Ki-67 in different histological grades and molecular subtypes of breast cancer focusing primarily on ER-positive tumors. MCM2 and Ki-67 mRNA expression were studied using in silico analysis of available DNA microarray and RNA-sequencing data of human breast cancer. We next used immunohistochemistry to evaluate protein expression of MCM2 and Ki-67 on tissue microarrays of invasive breast carcinoma. We found that MCM2 and Ki-67 are highly expressed in breast tumors of high histological grades, comprising clinically aggressive tumors such as triple-negative, HER2-positive and luminal B subtypes. MCM2 expression was detected at higher levels than that of Ki-67 in normal breast tissues and in breast cancers. The bimodal distribution of MCM2 scores in ER+/HER2- breast tumors led to the identification of two distinct subgroups with different relapse-free survival rates. In conclusion, MCM2 expression can help sorting out two clinically important subsets of luminal breast cancer whose treatment and clinical outcomes are likely to diverge.

Fabrication and demonstration of 1 × 8 silicon-silica multi-chip switch based on optical phased array

NASA Astrophysics Data System (ADS)

Katayose, Satomi; Hashizume, Yasuaki; Itoh, Mikitaka

2016-08-01

We experimentally demonstrated a 1 × 8 silicon-silica hybrid thermo-optic switch based on an optical phased array using a multi-chip integration technique. The switch consists of a silicon chip with optical phase shifters and two silica-based planar lightwave circuit (PLC) chips composed of optical couplers and fiber connections. We adopted a rib waveguide as the silicon waveguide to reduce the coupling loss and increase the alignment tolerance for coupling between silicon and silica waveguides. As a result, we achieved a fast switching response of 81 µs, a high extinction ratio of over 18 dB and a low insertion loss of 4.9-8.1 dB including a silicon-silica coupling loss of 0.5 ± 0.3 dB at a wavelength of 1.55 µm.

Facile and low temperature route to synthesis of CuS nanostructure in mesoporous material by solvothermal method.

PubMed

Sohrabnezhad, Sh; Zanjanchi, M A; Hosseingholizadeh, S; Rahnama, R

2014-04-05

The synthesis of CuS nanomaterial in MCM-41 matrix has been realized by chemical synthesis between MCM-41, copper sulfate pentahydrate and thiourea via a solvothermal method in ethylene glycol and water, separately. X-ray diffraction analysis (XRD), diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and fourier transform infrared (FT-IR) were used to characterize the products. At synthesized CuS/MCM-41 sample in ethylene glycol, X-ray diffraction and diffuse reflectance spectroscopy showed pure covellite phase of copper sulfide with high crystality. But prepared CuS/MCM-41 sample in water shows the covellite, chalcocite and the djurleite phase of copper sulfide nanostructures. The formation of CuS nanostructures was confirmed by FT-IR. Photocatalytic activity of CuS/MCM-41 nanocomposites was studied for degradation of Methylene Blue (MB) under visible light. The CuS/MCM-41 nanocomposite is more effective nanocatalyst than synthesized CuS/MCM-41 sample in water for degradation of methylene blue. Several parameters were examined, catalyst amount (0.1-1gL(-1)), pH (1-13) and initial concentration of MB (0.96-10ppm). The extent of degradation was estimated from the residual concentration by spectrophotometrically. The support size was obtained in the range 60-145nm by TEM. In the same way, the average size of copper sulfide in CuSMCM-41E and CuS/MCM-41W nanostructures were obtained about 10nm and 16nm, respectively. Copyright © 2013 Elsevier B.V. All rights reserved.

Sol–gel synthesis of MCM-41 silicas and selective vapor-phase modification of their surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roik, N.V., E-mail: roik_nadya@ukr.net; Belyakova, L.A.

2013-11-15

Silica particles with uniform hexagonal mesopore architecture were synthesized by template directed sol–gel condensation of tetraethoxysilane or mixture of tetraethoxysilane and (3-chloropropyl)triethoxysilane in a water–ethanol–ammonia solution. Selective functionalization of exterior surface of parent materials was carried out by postsynthetic treatment of template-filled MCM-41 and Cl-MCM-41 with vapors of (3-chloropropyl)triethoxysilane and 1,2-ethylenediamine in vacuum. The chemical composition of obtained mesoporous silicas was estimated by IR spectroscopy and chemical analysis of surface products of reactions. Characteristics of porous structure of resulting materials were determined from the data of X-ray, low-temperature nitrogen ad-desorption and transmission electron microscopy measurements. Obtained results confirm invariability ofmore » highly ordered mesoporous structure of MCM-41 and Cl-MCM-41 after their selective postsynthetic modification in vapor phase. It was proved that proposed method of vapor-phase functionalization of template-filled starting materials is not accompanied by dissolution of the template and chemical modification of pores surface. This provides preferential localization of grafted functional groups onto the exterior surface of mesoporous silicas. - Graphical abstract: Sol–gel synthesis and postsynthetic chemical modification of template-filled MCM-41 and Cl-MCM-41 with (3-chloropropyl)triethoxysilane and 1,2-ethylenediamine in vapor phase. Display Omitted - Highlights: • Synthesis of MCM-41 silica by template directed sol–gel condensation. • Selective vapor-phase functionalization of template-filled silica particles. • Preferential localization of grafted groups onto the exterior surface of mesoporous silicas.« less

Photocatalytic removal of Congo red dye using MCM-48/Ni2O3 composite synthesized based on silica gel extracted from rice husk ash; fabrication and application.

PubMed

Shaban, Mohamed; Abukhadra, Mostafa R; Hamd, Ahmed; Amin, Ragab R; Abdel Khalek, Ahmed

2017-12-15

MCM-48 mesoporous silica was successfully synthesized from silica gel extracted from rice husk ash and loaded by nickel oxide (Ni 2 O 3 ). The resulted composite was characterized using X-ray diffraction, scanning electron microscope, and UV-vis spectrophotometer. The role of MCM-48 as catalyst support in enhancing the photocatalytic properties of nickel oxide was evaluated through the photocatalytic degradation of Congo red dye under visible light source. MCM-48 as catalyst support for Ni 2 O 3 shows considerable enhancement in the adsorption capacity by 17% and 29% higher than the adsorption capacity of MCM-48 and Ni 2 O 3 , respectively. Additionally, the photocatalytic degradation percentage increased by about 64% relative to the degradation percentage using Ni 2 O 3 as a single component. The adsorption mechanism of MCM-48/Ni 2 O 3 is chemisorption process of multilayer form. The using of MCM-48 as catalyst support for Ni 2 O 3 enhanced the adsorption capacity and the photocatalytic degradation through increasing the surface area and prevents the nickel oxide particles from agglomeration. This was done through fixing nickel oxide particles throughout the porous structure which providing more exposed active adsorption sites and active photocatalyst sites for the incident photons. Based on the obtained results, supporting of nickel oxide particles onto MCM-48 are promising active centers for the degradation of Congo red dye molecules. Copyright © 2017 Elsevier Ltd. All rights reserved.

Role of DNA Replication Defects in Breast Cancer

DTIC Science & Technology

2010-10-01

effect is that C3H-Mcm4Chaos3/Chaos3 mice are developmentally normal, but Mcm4Chaos3/- animals die in utero or neonatally [Shima, 2007]. To further...3e). This increase in the ratio of reticulocytes (erythrocyte precursors) to mature RBCs is characteristic of anemia . Hemizygosity for Mcm3

Carbon dioxide adsorption on micro-mesoporous composite materials of ZSM-12/MCM-48 type: The role of the contents of zeolite and functionalized amine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Santos, S.C.G.; Pedrosa, A.M.Garrido; Souza, M.J.B., E-mail: mjbsufs@gmail.com

2015-10-15

Highlights: • Synthesis of the micro-mesoporous composite materials of ZSM-12/MCM-48 type. • Application of these adsorbents in the carbon dioxide adsorption. • Effects of the contents of zeolite and amino group in the material surface on the CO{sub 2} capture efficiency. - Abstract: In this study ZSM-12/MCM-48 adsorbents have been synthesized at three ZSM-12 content, and also were functionalizated with amine groups by grafting. All the adsorbents synthesized were evaluated for CO{sub 2} capture. The X-ray diffraction analysis of the ZSM-12/MCM-48 composite showed the main characteristic peaks of ZSM-12 and MCM-48, and after the functionalization, the structure of MCM-48 onmore » the composite impregnated was affected due amine presence. For the composites without amine, the ZSM-12 content was the factor determining in the adsorption capacity of CO{sub 2} and for the composites with amine the amount of amine was that influenced in the adsorption capacity.« less

A MADS Box Protein Interacts with a Mating-Type Protein and Is Required for Fruiting Body Development in the Homothallic Ascomycete Sordaria macrospora

PubMed Central

Nolting, Nicole; Pöggeler, Stefanie

2006-01-01

MADS box transcription factors control diverse developmental processes in plants, metazoans, and fungi. To analyze the involvement of MADS box proteins in fruiting body development of filamentous ascomycetes, we isolated the mcm1 gene from the homothallic ascomycete Sordaria macrospora, which encodes a putative homologue of the Saccharomyces cerevisiae MADS box protein Mcm1p. Deletion of the S. macrospora mcm1 gene resulted in reduced biomass, increased hyphal branching, and reduced hyphal compartment length during vegetative growth. Furthermore, the S. macrospora Δmcm1 strain was unable to produce fruiting bodies or ascospores during sexual development. A yeast two-hybrid analysis in conjugation with in vitro analyses demonstrated that the S. macrospora MCM1 protein can interact with the putative transcription factor SMTA-1, encoded by the S. macrospora mating-type locus. These results suggest that the S. macrospora MCM1 protein is involved in the transcriptional regulation of mating-type-specific genes as well as in fruiting body development. PMID:16835449

MCM ring hexamerization is a prerequisite for DNA-binding

DOE PAGES

Froelich, Clifford A.; Nourse, Amanda; Enemark, Eric J.

2015-09-13

The hexameric Minichromosome Maintenance (MCM) protein complex forms a ring that unwinds DNA at the replication fork in eukaryotes and archaea. Our recent crystal structure of an archaeal MCM N-terminal domain bound to single-stranded DNA (ssDNA) revealed ssDNA associating across tight subunit interfaces but not at the loose interfaces, indicating that DNA-binding is governed not only by the DNA-binding residues of the subunits (MCM ssDNA-binding motif, MSSB) but also by the relative orientation of the subunits. We now extend these findings to show that DNA-binding by the MCM N-terminal domain of the archaeal organism Pyrococcus furiosus occurs specifically in themore » hexameric oligomeric form. We show that mutants defective for hexamerization are defective in binding ssDNA despite retaining all the residues observed to interact with ssDNA in the crystal structure. One mutation that exhibits severely defective hexamerization and ssDNA-binding is at a conserved phenylalanine that aligns with the mouse Mcm4(Chaos3) mutation associated with chromosomal instability, cancer, and decreased intersubunit association.« less

Photocatalytic degradation of isoproturon herbicide over TiO2/Al-MCM-41 composite systems using solar light.

PubMed

Phanikrishna Sharma, M V; Durga Kumari, V; Subrahmanyam, M

2008-06-01

The present investigation covers immobilization of TiO2 using a simple solid state dispersion technique over mesoporous Al-MCM-41 support for the treatment of isoproturon herbicide. Catalysts are characterized by XRD, X-ray photo electron spectroscopy (XPS), surface area, UV-Vis diffused reflectance spectra (DRS), SEM and TEM. A detailed photocatalytic degradation study of isoproturon under solar light in aqueous suspensions is reported. The 10 wt% TiO2/Al-MCM-41 composite system found to be optimum with high degradation activity. The reaction follows pseudo-first order kinetics. The parameters like TiO2 loading over Al-MCM-41, amount of catalyst, concentration of substrate, pH effect, durability of the catalyst, activity comparison of TiO2 and Al-MCM-41 supported system are studied. The mineralization of isoproturon is monitored by TOC. Based on the degradation products detected through LC-MS, a plausible degradation mechanism is proposed. The data indicates that TiO2/Al-MCM-41 composite system is an effective photocatalyst for treatment of isoproturon in contaminated water.

Selective Catalytic Reduction of NO with NH3 Over V-MCM-41 Catalyst.

PubMed

Kwon, Woo Hyun; Park, Sung Hoon; Kim, Ji Man; Park, Su Bin; Jung, Sang-Chul; Kim, Sang Chai; Jeon, Jong-Ki; Park, Young-Kwon

2016-02-01

V-MCM-41, a mesoporous catalyst doped with V2O5, was applied for the first time to the removal of atmospheric NO. The quantity of V2O5 added was 10 wt% and 30 wt%. The characteristics of the synthesized catalysts were examined using XRD, N2 soprtion, and NH3-TPD. With increasing quantity of V2O5 added, specific surface area decreased and pore size increased. When the quantity of V2O5 was 10 wt%, the MCM-41 structure was retained, whereas considerable collapse of mesoporous structure was observed when 30 wt% V2O5 was added. The examination of acid characteristics using NH3-TPD showed that 30 wt% V-MCM-41 had the higher NH3 adsorption ability, implying that it would exhibit high activity for NH3 SCR reaction. In the NO removal experiments, 30 wt% V-MCM-41 showed much higher NO removal efficiency than 10 wt% V-MCM-41, which was attributed to its high NH3 adsorption ability.

Analyzing adsorption characteristics of CO2, N2 and H2O in MCM-41 silica by molecular simulation

NASA Astrophysics Data System (ADS)

Chang, Shing-Cheng; Chien, Shih-Yao; Chen, Chieh-Li; Chen, Cha'o.-Kuang

2015-03-01

The adsorption characteristics of carbon dioxide, nitrogen and water molecules in MCM-41 mesoporous molecular sieve have been investigated by the molecular simulation. We evaluate the pressure-adsorption isotherms and adsorption density profiles under variant gas pressure, operating temperature and mesopore radius of MCM-41 by the grand canonical Monte Carlo simulation. According to the calculated adsorption energy distributions, the adsorption mechanisms of gas in MCM-41 are mainly divided into three types, namely "surface adsorption" on the pore wall, "multilayer adsorption" on the adsorbed gas molecules and "molecular self-aggregation" near the pore center. In addition, the adsorption characteristics of water molecules in MCM-41 are found to be quite different from those of carbon dioxide and nitrogen due to the hydrogen bonds effect. The results indicate that the MCM-41 is practicable in engineering application for the capture, storage, and re-use of water molecules, since it is temperature-sensitive and can achieve significant adsorption loadings within a small range of pressure values via the capillary condensation phenomena.

An analysis of the pull strength behaviors of fine-pitch, flip chip solder interconnections using a Au-Pt-Pd thick film conductor on Low-Temperature, Co-fired Ceramic (LTCC) substrates.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uribe, Fernando R.; Kilgo, Alice C.; Grazier, John Mark

2008-09-01

The assembly of the BDYE detector requires the attachment of sixteen silicon (Si) processor dice (eight on the top side; eight on the bottom side) onto a low-temperature, co-fired ceramic (LTCC) substrate using 63Sn-37Pb (wt.%, Sn-Pb) in a double-reflow soldering process (nitrogen). There are 132 solder joints per die. The bond pads were gold-platinum-palladium (71Au-26Pt-3Pd, wt.%) thick film layers fired onto the LTCC in a post-process sequence. The pull strength and failure modes provided the quality metrics for the Sn-Pb solder joints. Pull strengths were measured in both the as-fabricated condition and after exposure to thermal cycling (-55/125 C; 15more » min hold times; 20 cycles). Extremely low pull strengths--referred to as the low pull strength phenomenon--were observed intermittently throughout the product build, resulting in added program costs, schedule delays, and a long-term reliability concern for the detector. There was no statistically significant correlation between the low pull strength phenomenon and (1) the LTCC 'sub-floor' lot; (2) grit blasting the LTCC surfaces prior to the post-process steps; (3) the post-process parameters; (4) the conductor pad height (thickness); (5) the dice soldering assembly sequence; or (5) the dice pull test sequence. Formation of an intermetallic compound (IMC)/LTCC interface caused by thick film consumption during either the soldering process or by solid-state IMC formation was not directly responsible for the low-strength phenomenon. Metallographic cross sections of solder joints from dice that exhibited the low pull strength behavior, revealed the presence of a reaction layer resulting from an interaction between Sn from the molten Sn-Pb and the glassy phase at the TKN/LTCC interface. The thick film porosity did not contribute, explicitly, to the occurrence of reaction layer. Rather, the process of printing the very thin conductor pads was too sensitive to minor thixotropic changes to ink, which resulted in inconsistent proportions of metal and glassy phase particles present during the subsequent firing process. The consequences were subtle, intermittent changes to the thick film microstructure that gave rise to the reaction layer and, thus, the low pull strength phenomenon. A mitigation strategy would be the use of physical vapor deposition (PVD) techniques to create thin film bond pads; this is multi-chip module, deposited (MCM-D) technology.« less

Genome-wide chromatin footprinting reveals changes in replication origin architecture induced by pre-RC assembly

PubMed Central

MacAlpine, Heather K.; Lubelsky, Yoav; Hartemink, Alexander J.

2015-01-01

Start sites of DNA replication are marked by the origin recognition complex (ORC), which coordinates Mcm2–7 helicase loading to form the prereplicative complex (pre-RC). Although pre-RC assembly is well characterized in vitro, the process is poorly understood within the local chromatin environment surrounding replication origins. To reveal how the chromatin architecture modulates origin selection and activation, we “footprinted” nucleosomes, transcription factors, and replication proteins at multiple points during the Saccharomyces cerevisiae cell cycle. Our nucleotide-resolution protein occupancy profiles resolved a precise ORC-dependent footprint at 269 origins in G2. A separate class of inefficient origins exhibited protein occupancy only in G1, suggesting that stable ORC chromatin association in G2 is a determinant of origin efficiency. G1 nucleosome remodeling concomitant with pre-RC assembly expanded the origin nucleosome-free region and enhanced activation efficiency. Finally, the local chromatin environment restricts the loading of the Mcm2–7 double hexamer either upstream of or downstream from the ARS consensus sequence (ACS). PMID:25593310

Transcription factor genes essential for cell proliferation and replicative lifespan in budding yeast

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kamei, Yuka; Tai, Akiko; Dakeyama, Shota

Many of the lifespan-related genes have been identified in eukaryotes ranging from the yeast to human. However, there is limited information available on the longevity genes that are essential for cell proliferation. Here, we investigated whether the essential genes encoding DNA-binding transcription factors modulated the replicative lifespan of Saccharomyces cerevisiae. Heterozygous diploid knockout strains for FHL1, RAP1, REB1, and MCM1 genes showed significantly short lifespan. {sup 1}H-nuclear magnetic resonance analysis indicated a characteristic metabolic profile in the Δfhl1/FHL1 mutant. These results strongly suggest that FHL1 regulates the transcription of lifespan related metabolic genes. Thus, heterozygous knockout strains could be themore » potential materials for discovering further novel lifespan genes. - Highlights: • Involvement of yeast TF genes essential for cell growth in lifespan was evaluated. • The essential TF genes, FHL1, RAP1, REB1, and MCM1, regulate replicative lifespan. • Heterozygous deletion of FHL1 changes cellular metabolism related to lifespan.« less

The Correlation of Adsorption Behavior between Ciprofloxacin Hydrochloride and the Active Sites of Fe-doped MCM-41.

PubMed

Wu, Ying; Tang, Yiming; Li, Laisheng; Liu, Peihong; Li, Xukai; Chen, Weirui; Xue, Ying

2018-01-01

HIGHLIGHTS Fe incorporation significantly accelerated the adsorption of CPX on MCM-41.Fe leaching can be ignored when pH was higher than 4.0.pH played an important role in CPX adsorption on Fe-MCM-41.Co-effect of CPX and metal cations on Fe-MCM-41 was investigated. Fe-MCM-41s with various molar ratios of silicon to iron (20, 40, 80, and 160) were prepared to investigate adsorption properties of ciprofloxacin hydrochloride (CPX) in aqueous solutions. Fe-MCM-41s were characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption/desorption isotherms, and infrared spectroscopy (FT-IR). Effects of silicon-iron ratio, adsorbent dosage, pH, and temperature were conducted to explore the adsorption mechanism of CPX on Fe-MCM-41. The results showed that the introduction of iron facilitated the absorption quantity for CPX from 20.04 to 83.33 mg g -1 at 120 min of reaction time, which was mainly attributed to surface complexation. The promotion of hydrophobic effect, electrostatic interactions, and π-π electron donor-acceptor interaction also played coordinate roles in the adsorption process. The experimental kinetic data followed both the pseudo-second-order and intra-particle diffusion models, while the adsorption isotherm data fit well to Freundlich model at high temperature. Thermodynamic study showed that the adsorption was spontaneous. Under the effect of electrostatic interaction, pH of the solution strongly affected CPX adsorption. Five representative metal cations (Ca, Cu, Ni, Pb, and Cd) were chosen to study the effects on CPX adsorption and their complexation. The inhibiting effect of metal cations on CPX adsorption was sequenced in the order of Cu > Ni > Pb > Cd > Ca, which followed the same order as the complexation stability constants between CPX and cations. The Fe-MCM-41 adsorbent possessed excellent reusability for 4 cycles use, suggesting a potential applicability of Fe-MCM-41 to remove CPX in water.

The Correlation of Adsorption Behavior between Ciprofloxacin Hydrochloride and the Active Sites of Fe-doped MCM-41

PubMed Central

Wu, Ying; Tang, Yiming; Li, Laisheng; Liu, Peihong; Li, Xukai; Chen, Weirui; Xue, Ying

2018-01-01

HIGHLIGHTS Fe incorporation significantly accelerated the adsorption of CPX on MCM-41.Fe leaching can be ignored when pH was higher than 4.0.pH played an important role in CPX adsorption on Fe-MCM-41.Co-effect of CPX and metal cations on Fe-MCM-41 was investigated. Fe-MCM-41s with various molar ratios of silicon to iron (20, 40, 80, and 160) were prepared to investigate adsorption properties of ciprofloxacin hydrochloride (CPX) in aqueous solutions. Fe-MCM-41s were characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption/desorption isotherms, and infrared spectroscopy (FT-IR). Effects of silicon-iron ratio, adsorbent dosage, pH, and temperature were conducted to explore the adsorption mechanism of CPX on Fe-MCM-41. The results showed that the introduction of iron facilitated the absorption quantity for CPX from 20.04 to 83.33 mg g−1 at 120 min of reaction time, which was mainly attributed to surface complexation. The promotion of hydrophobic effect, electrostatic interactions, and π-π electron donor-acceptor interaction also played coordinate roles in the adsorption process. The experimental kinetic data followed both the pseudo-second-order and intra-particle diffusion models, while the adsorption isotherm data fit well to Freundlich model at high temperature. Thermodynamic study showed that the adsorption was spontaneous. Under the effect of electrostatic interaction, pH of the solution strongly affected CPX adsorption. Five representative metal cations (Ca, Cu, Ni, Pb, and Cd) were chosen to study the effects on CPX adsorption and their complexation. The inhibiting effect of metal cations on CPX adsorption was sequenced in the order of Cu > Ni > Pb > Cd > Ca, which followed the same order as the complexation stability constants between CPX and cations. The Fe-MCM-41 adsorbent possessed excellent reusability for 4 cycles use, suggesting a potential applicability of Fe-MCM-41 to remove CPX in water. PMID:29468153

The haloarchaeal MCM proteins: bioinformatic analysis and targeted mutagenesis of the β7-β8 and β9-β10 hairpin loops and conserved zinc binding domain cysteines.

PubMed

Kristensen, Tatjana P; Maria Cherian, Reeja; Gray, Fiona C; MacNeill, Stuart A

2014-01-01

The hexameric MCM complex is the catalytic core of the replicative helicase in eukaryotic and archaeal cells. Here we describe the first in vivo analysis of archaeal MCM protein structure and function relationships using the genetically tractable haloarchaeon Haloferax volcanii as a model system. Hfx. volcanii encodes a single MCM protein that is part of the previously identified core group of haloarchaeal MCM proteins. Three structural features of the N-terminal domain of the Hfx. volcanii MCM protein were targeted for mutagenesis: the β7-β8 and β9-β10 β-hairpin loops and putative zinc binding domain. Five strains carrying single point mutations in the β7-β8 β-hairpin loop were constructed, none of which displayed impaired cell growth under normal conditions or when treated with the DNA damaging agent mitomycin C. However, short sequence deletions within the β7-β8 β-hairpin were not tolerated and neither was replacement of the highly conserved residue glutamate 187 with alanine. Six strains carrying paired alanine substitutions within the β9-β10 β-hairpin loop were constructed, leading to the conclusion that no individual amino acid within that hairpin loop is absolutely required for MCM function, although one of the mutant strains displays greatly enhanced sensitivity to mitomycin C. Deletions of two or four amino acids from the β9-β10 β-hairpin were tolerated but mutants carrying larger deletions were inviable. Similarly, it was not possible to construct mutants in which any of the conserved zinc binding cysteines was replaced with alanine, underlining the likely importance of zinc binding for MCM function. The results of these studies demonstrate the feasibility of using Hfx. volcanii as a model system for reverse genetic analysis of archaeal MCM protein function and provide important confirmation of the in vivo importance of conserved structural features identified by previous bioinformatic, biochemical and structural studies.

Highly Loaded Fe-MCM-41 Materials: Synthesis and Reducibility Studies

PubMed Central

Mokhonoana, Malose P.; Coville, Neil J.

2009-01-01

Fe-MCM-41 materials were prepared by different methods. The Fe was both incorporated into the structure and formed crystallites attached to the silica. High Fe content MCM-41 (~16 wt%) with retention of mesoporosity and long-range order was achieved by a range of new synthetic methodologies: (i) by delaying the addition of Fe3+(aq) to the stirred synthesis gel by 2 h, (ii) by addition of Fe3+ precursor as a freshly-precipitated aqueous slurry, (iii) by exploiting a secondary synthesis with Si-MCM-41 as SiO2 source. For comparative purposes the MCM-41 was also prepared by incipient wetness impregnation (IWI). Although all these synthesis methods preserved mesoporosity and long-range order of the SiO2 matrix, the hydrothermally-fabricated Fe materials prepared via the secondary synthesis route has the most useful properties for exploitation as a catalyst, in terms of hydrothermal stability of the resulting support. Temperature-programmed reduction (TPR) studies revealed a three-peak reduction pattern for this material instead of the commonly observed two-peak reduction pattern. The three peaks showed variable intensity that related to the presence of two components: crystalline Fe2O3 and Fe embedded in the SiO2 matrix (on the basis of ESR studies). The role of secondary synthesis of Si-MCM-41 on the iron reducibility was also demonstrated in IWI of sec-Si-MCM-41.

Comparison between immunohistochemical expression of Ki-67 and MCM-3 in major salivary gland epithelial tumors in children and adolescents. Preliminary study.

PubMed

Zieliński, Rafał; Kobos, Jozef; Zakrzewska, Anna

While Ki-67 expression is frequently used as an indicator of tumor cell proliferation, alternative markers have also been proposed. Possible alternative indicators of proliferation are the minichromosome maintenance (MCM) proteins, whose levels are inversely associated with tumor cell differentiation. The aim of this preliminary study was to compare the levels of Ki-67 and MCM-3 expression in major salivary gland epithelial tumors in all children and adolescents who underwent surgery in our department in the years 2009-2014. The histopathological diagnosis of the subjects was reviewed, as well as the expression of Ki-67 and MCM-3 in post-op specimens of the tumors. The normality of data was checked with the Shapiro-Wilk test. The t test for independent variables or the U test was used as appropriate to determine statistically significant differences in the expression of Ki-67 and MCM-3. Five cases of pleomorphic adenoma, one of myoepithelioma, one of basal cell adenoma and one of mucoepidermoid carcinoma were identified. Significantly greater MCM-3 than Ki-67 expression was observed in every case. The results of our preliminary study emphasize the need for future research on MCM-3 as a sensitive proliferation marker, providing an alternative to Ki-67, in cases of various major salivary gland epithelial tumors in children and adolescents.

ATR Performance Estimation Seed Program

DTIC Science & Technology

2015-09-28

to produce simulated MCM sonar data and demonstrate the impact of system, environmental, and target scattering effects on ATR detection...settings and achieving better understanding the relative impact of the factors influencing ATR performance. sonar, mine countermeasures, MCM , automatic...simulated MCM sonar data and demonstrate the impact of system, environmental, and target scattering effects on ATR detection/classification performance. The

Cross-Species Rhesus Cytomegalovirus Infection of Cynomolgus Macaques

PubMed Central

Bimber, Benjamin N.; Reed, Jason S.; Uebelhoer, Luke S.; Bhusari, Amruta; Hammond, Katherine B.; Klug, Alex; Legasse, Alfred W.; Axthelm, Michael K.; Nelson, Jay A.; Streblow, Daniel N.; Picker, Louis J.; Früh, Klaus; Sacha, Jonah B.

2016-01-01

Cytomegaloviruses (CMV) are highly species-specific due to millennia of co-evolution and adaptation to their host, with no successful experimental cross-species infection in primates reported to date. Accordingly, full genome phylogenetic analysis of multiple new CMV field isolates derived from two closely related nonhuman primate species, Indian-origin rhesus macaques (RM) and Mauritian-origin cynomolgus macaques (MCM), revealed distinct and tight lineage clustering according to the species of origin, with MCM CMV isolates mirroring the limited genetic diversity of their primate host that underwent a population bottleneck 400 years ago. Despite the ability of Rhesus CMV (RhCMV) laboratory strain 68–1 to replicate efficiently in MCM fibroblasts and potently inhibit antigen presentation to MCM T cells in vitro, RhCMV 68–1 failed to productively infect MCM in vivo, even in the absence of host CD8+ T and NK cells. In contrast, RhCMV clone 68–1.2, genetically repaired to express the homologues of the HCMV anti-apoptosis gene UL36 and epithelial cell tropism genes UL128 and UL130 absent in 68–1, efficiently infected MCM as evidenced by the induction of transgene-specific T cells and virus shedding. Recombinant variants of RhCMV 68–1 and 68–1.2 revealed that expression of either UL36 or UL128 together with UL130 enabled productive MCM infection, indicating that multiple layers of cross-species restriction operate even between closely related hosts. Cumulatively, these results implicate cell tropism and evasion of apoptosis as critical determinants of CMV transmission across primate species barriers, and extend the macaque model of human CMV infection and immunology to MCM, a nonhuman primate species with uniquely simplified host immunogenetics. PMID:27829026

NASA Tech Briefs, June 2009

NASA Technical Reports Server (NTRS)

2009-01-01

Topics covered include: Device for Measuring Low Flow Speed in a Duct, Measuring Thermal Conductivity of a Small Insulation Sample, Alignment Jig for the Precise Measurement of THz Radiation, Autoignition Chamber for Remote Testing of Pyrotechnic Devices, Microwave Power Combiners for Signals of Arbitrary Amplitude, Synthetic Foveal Imaging Technology, Airborne Antenna System for Minimum-Cycle-Slip GPS Reception, Improved Starting Materials for Back-Illuminated Imagers, Multi-Modulator for Bandwidth-Efficient Communication, Some Improvements in Utilization of Flash Memory Devices, GPS/MEMS IMU/Microprocessor Board for Navigation, T/R Multi-Chip MMIC Modules for 150 GHz, Pneumatic Haptic Interfaces, Device Acquires and Retains Rock or Ice Samples, Cryogenic Feedthrough Test Rig, Improved Assembly for Gas Shielding During Welding or Brazing, Two-Step Plasma Process for Cleaning Indium Bonding Bumps, Tool for Crimping Flexible Circuit Leads, Yb14MnSb11 as a High-Efficiency Thermoelectric Material, Polyimide-Foam/Aerogel Composites for Thermal Insulation, Converting CSV Files to RKSML Files, Service Management Database for DSN Equipment, Chemochromic Hydrogen Leak Detectors, Compatibility of Segments of Thermoelectric Generators, Complementary Barrier Infrared Detector, JPL Greenland Moulin Exploration Probe, Ultra-Lightweight Self-Deployable Nanocomposite Structure for Habitat Applications, and Room-Temperature Ionic Liquids for Electrochemical Capacitors.

Modified silica-based heterogeneous catalysts for etherification of glycerol

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gholami, Zahra, E-mail: zahra.gholami@petronas.com.my; Abdullah, Ahmad Zuhairi, E-mail: chzuhairi@usm.my; Gholami, Fatemeh, E-mail: fgholami59@gmail.com

2015-07-22

The advent of mesoporous silicas such as MCM-41 has provided new opportunities for research into supported metal catalysis. The loading of metals into framework structures and particularly into the pores of porous molecular sieves, has long been of interest because of their potential catalytic activity. Stable heterogeneous mesoporous basic catalysts were synthesized by wet impregnation of MCM-41 with calcium nitrate and lanthanum nitrate. The surface and structural properties of the prepared catalysts were characterized using BET surface analysis, SEM and TEM. MCM-41 and modified MCM-41 were used in the solventless etherification of glycerol to produce diglycerol as the desired product.more » The reaction was performed at 250 °C for 8 h, and catalyst activity was evaluated. Catalytic etherification over the 20%Ca{sub 1.6}La{sub 0.6}/MCM-41 catalyst resulted in the highest glycerol conversion of 91% and diglycerol yield of 43%.« less

Synthesis and catalytic performance of ZSM-5/MCM-41 composite molecular sieve from palygorskite

NASA Astrophysics Data System (ADS)

Jiang, Jinlong; Wu, Mei; Yang, Yong; Duanmu, Chuansong; Chen, Jing; Gu, Xu

2017-10-01

ZSM-5/MCM-41 composite molecular sieve has been hydrothermally synthesized through a two-step crystallization process using palygorskite (PAL) as silicon and aluminum source. The products were characterized by various means and their catalytic properties for acetalization of cyclohexanone and esterification of acetic acid and n-butanol were also investigated. In the first step ZSM-5 zeolite could be formed from the acid-treated PAL after hydrothermal treatment using tetrapropylammonium bromide as template. XRD patterns, N2 adsorption and desorption data, and TEM images show that the composite obtained in the secondary step had a well-ordered mesoporous MCM-41 phase and a microporous ZSM-5 zeolite phase. Compared with ZSM-5, ZSM-5/MCM-41 composite possessed more total acid amount, weak acid sites and large pore structure due to the formation of MCM-41 and exhibited higher catalytic activity for the acetalization and esterification reaction.

Comprehensive Characterization of Minichromosome Maintenance Complex (MCM) Protein Interactions Using Affinity and Proximity Purifications Coupled to Mass Spectrometry.

PubMed

Dubois, Marie-Line; Bastin, Charlotte; Lévesque, Dominique; Boisvert, François-Michel

2016-09-02

The extensive identification of protein-protein interactions under different conditions is an important challenge to understand the cellular functions of proteins. Here we use and compare different approaches including affinity purification and purification by proximity coupled to mass spectrometry to identify protein complexes. We explore the complete interactome of the minichromosome maintenance (MCM) complex by using both approaches for all of the different MCM proteins. Overall, our analysis identified unique and shared interaction partners and proteins enriched for distinct biological processes including DNA replication, DNA repair, and cell cycle regulation. Furthermore, we mapped the changes in protein interactions of the MCM complex in response to DNA damage, identifying a new role for this complex in DNA repair. In summary, we demonstrate the complementarity of these approaches for the characterization of protein interactions within the MCM complex.

180-GHz Interferometric Imager

NASA Technical Reports Server (NTRS)

Kangaslahti, Pekka P.; Lim, Boon H.; O'Dwyer, Ian J.; Soria, Mary M.; Owen, Heather R.; Gaier, Todd C.; Lambrigtsen, Bjorn, H.; Tanner, Alan B.; Ruf, Christopher

2011-01-01

A 180-GHz interferometric imager uses compact receiver modules, combined high- and low-gain antennas, and ASIC (application specific integrated circuit) correlator technology, enabling continuous, all-weather observations of water vapor with 25-km resolution and 0.3-K noise in 15 minutes of observation for numerical weather forecasting and tropical storm prediction. The GeoSTAR-II prototype instrument is broken down into four major subsystems: the compact, low-noise receivers; sub-array modules; IF signal distribution; and the digitizer/correlator. Instead of the single row of antennas adopted in GeoSTAR, this version has four rows of antennas on a coarser grid. This dramatically improves the sensitivity in the desired field of view. The GeoSTAR-II instrument is a 48-element, synthetic, thinned aperture radiometer operating at 165-183 GHz. The instrument has compact receivers integrated into tiles of 16 elements in a 4x4 arrangement. These tiles become the building block of larger arrays. The tiles contain signal distribution for bias controls, IF signal, and local oscillator signals. The IF signals are digitized and correlated using an ASIC correlator to minimize power consumption. Previous synthetic aperture imagers have used comparatively large multichip modules, whereas this approach uses chip-scale modules mounted on circuit boards, which are in turn mounted on the distribution manifolds. This minimizes the number of connectors and reduces system mass. The use of ASIC technology in the digitizers and correlators leads to a power reduction close to an order of magnitude.

Advanced Materials for High Temperature, High Performance, Wide Bandgap Power Modules

NASA Astrophysics Data System (ADS)

O'Neal, Chad B.; McGee, Brad; McPherson, Brice; Stabach, Jennifer; Lollar, Richard; Liederbach, Ross; Passmore, Brandon

2016-01-01

Advanced packaging materials must be utilized to take full advantage of the benefits of the superior electrical and thermal properties of wide bandgap power devices in the development of next generation power electronics systems. In this manuscript, the use of advanced materials for key packaging processes and components in multi-chip power modules will be discussed. For example, to date, there has been significant development in silver sintering paste as a high temperature die attach material replacement for conventional solder-based attach due to the improved thermal and mechanical characteristics as well as lower processing temperatures. In order to evaluate the bond quality and performance of this material, shear strength, thermal characteristics, and void quality for a number of silver sintering paste materials were analyzed as a die attach alternative to solder. In addition, as high voltage wide bandgap devices shift from engineering samples to commercial components, passivation materials become key in preventing premature breakdown in power modules. High temperature, high dielectric strength potting materials were investigated to be used to encapsulate and passivate components internal to a power module. The breakdown voltage up to 30 kV and corresponding leakage current for these materials as a function of temperature is also presented. Lastly, high temperature plastic housing materials are important for not only discrete devices but also for power modules. As the operational temperature of the device and/or ambient temperature increases, the mechanical strength and dielectric properties are dramatically reduced. Therefore, the electrical characteristics such as breakdown voltage and leakage current as a function of temperature for housing materials are presented.

Polyethylenimine-modified curcumin-loaded mesoporus silica nanoparticle (MCM-41) induces cell death in MCF-7 cell line.

PubMed

Harini, Lakshminarasimhan; Karthikeyan, Bose; Srivastava, Sweta; Suresh, Srinag Bangalore; Ross, Cecil; Gnanakumar, Georgepeter; Rajagopal, Srinivasan; Sundar, Krishnan; Kathiresan, Thandavarayan

2017-02-01

Breast cancer accounts for the first highest mortality rate in India and second in world. Though current treatment strategies are effectively killing cancer cells, they also end in causing severe side effects and drug resistance. Curcumin is a nutraceutical with multipotent activity but its insolubility in water limits its therapeutic potential as an anti-cancer drug. The hydrophilicity of curcumin could be increased by nanoformulation or changing its functional groups. In this study, curcumin is loaded on mesoporous silica nanoparticle and its anti-cancer activity is elucidated with MCF-7 cell death. Structural characteristics of Mobil Composition of Matter - 41(MCM-41) as determined by high-resolution transmission electron microscopy (HR-TEM) shows that MCM-41 size ranges from 100 to 200 nm diameters with pore size 2-10 nm for drug adsorption. The authors found 80-90% of curcumin is loaded on MCM-41 and curcumin is released efficiently at pH 3.0. The 50 µM curcumin-loaded MCM-41 induced 50% mortality of MCF-7 cells. Altogether, their results suggested that increased curcumin loading and sustained release from MCM-41 effectively decreased cell survival of MCF-7 cells in vitro.

DNA binding polarity, dimerization, and ATPase ring remodeling in the CMG helicase of the eukaryotic replisome

PubMed Central

Costa, Alessandro; Renault, Ludovic; Swuec, Paolo; Petojevic, Tatjana; Pesavento, James J; Ilves, Ivar; MacLellan-Gibson, Kirsty; Fleck, Roland A; Botchan, Michael R; Berger, James M

2014-01-01

The Cdc45/Mcm2-7/GINS (CMG) helicase separates DNA strands during replication in eukaryotes. How the CMG is assembled and engages DNA substrates remains unclear. Using electron microscopy, we have determined the structure of the CMG in the presence of ATPγS and a DNA duplex bearing a 3′ single-stranded tail. The structure shows that the MCM subunits of the CMG bind preferentially to single-stranded DNA, establishes the polarity by which DNA enters into the Mcm2-7 pore, and explains how Cdc45 helps prevent DNA from dissociating from the helicase. The Mcm2-7 subcomplex forms a cracked-ring, right-handed spiral when DNA and nucleotide are bound, revealing unexpected congruencies between the CMG and both bacterial DnaB helicases and the AAA+ motor of the eukaryotic proteasome. The existence of a subpopulation of dimeric CMGs establishes the subunit register of Mcm2-7 double hexamers and together with the spiral form highlights how Mcm2-7 transitions through different conformational and assembly states as it matures into a functional helicase. DOI: http://dx.doi.org/10.7554/eLife.03273.001 PMID:25117490

Lysine-Grafted MCM-41 Silica as an Antibacterial Biomaterial.

PubMed

Villegas, María F; Garcia-Uriostegui, Lorena; Rodríguez, Ofelia; Izquierdo-Barba, Isabel; Salinas, Antonio J; Toriz, Guillermo; Vallet-Regí, María; Delgado, Ezequiel

2017-09-26

This paper proposes a facile strategy for the zwitterionization of bioceramics that is based on the direct incorporation of l-lysine amino acid via the ε-amino group onto mesoporous MCM-41 materials. Fourier transform infrared (FTIR) studies of lysine-grafted MCM-41 (MCM-LYS) simultaneously showed bands at 3080 and 1540 cm -1 and bands at 1625 and 1415 cm -1 corresponding to -NH 3+ /COO - pairs, which demonstrate the incorporation of the amino acid on the material surface keeping its zwitterionic character. Both elemental and thermogravimetric analyses showed that the amount of grafted lysine was 8 wt. % based on the bioceramic total weight. Moreover, MCM-LYS exhibited a reduction of adhesion of S. aureus and E. coli bacteria in 33% and 50%, respectively at physiological pH, as compared with pristine MCM-41. Biofilm studies onto surfaces showed that lysine functionalization elicited a reduction of the area covered by S. aureus biofilm from 42% to only 5% (88%). This research shows a simple and effective approach to chemically modify bioceramics using single amino acids that provides zwitterionic functionality, which is useful to develop new biomaterials that are able to resist bacterial adhesion.

Lysine-Grafted MCM-41 Silica as an Antibacterial Biomaterial

PubMed Central

Villegas, María F.; Garcia-Uriostegui, Lorena; Rodríguez, Ofelia; Izquierdo-Barba, Isabel; Salinas, Antonio J.; Toriz, Guillermo; Vallet-Regí, María; Delgado, Ezequiel

2017-01-01

This paper proposes a facile strategy for the zwitterionization of bioceramics that is based on the direct incorporation of l-lysine amino acid via the ε-amino group onto mesoporous MCM-41 materials. Fourier transform infrared (FTIR) studies of lysine-grafted MCM-41 (MCM-LYS) simultaneously showed bands at 3080 and 1540 cm−1 and bands at 1625 and 1415 cm−1 corresponding to -NH3+/COO− pairs, which demonstrate the incorporation of the amino acid on the material surface keeping its zwitterionic character. Both elemental and thermogravimetric analyses showed that the amount of grafted lysine was 8 wt. % based on the bioceramic total weight. Moreover, MCM-LYS exhibited a reduction of adhesion of S. aureus and E. coli bacteria in 33% and 50%, respectively at physiological pH, as compared with pristine MCM-41. Biofilm studies onto surfaces showed that lysine functionalization elicited a reduction of the area covered by S. aureus biofilm from 42% to only 5% (88%). This research shows a simple and effective approach to chemically modify bioceramics using single amino acids that provides zwitterionic functionality, which is useful to develop new biomaterials that are able to resist bacterial adhesion. PMID:28952559

Tailoring pore properties of MCM-48 silica for selective adsorption of CO2.

PubMed

Kim, Sangil; Ida, Junichi; Guliants, Vadim V; Lin, Jerry Y S

2005-04-07

Four different types of amine-attached MCM-48 silicas were prepared and investigated for CO(2) separation from N(2). Monomeric and polymeric hindered and unhindered amines were attached to the pore surface of the MCM-48 silica and characterized with respect to their CO(2) sorption properties. The pore structures and amino group content in these modified silicas were investigated by XRD, FT-IR, TGA, N(2) adsorption/desorption at 77 K and CHN/Si analysis, which confirmed that in all cases the amino groups were attached to the pore surface of MCM-48 at 1.5-5.2 mmol/g. The N(2) adsorption/desorption analysis showed a considerable decrease of the pore volume and surface area for the MCM-48 silica containing a polymeric amine (e.g., polyethyleneimine). The CO(2) adsorption rates and capacities of the amine-attached MCM-48 samples were studied employing a sorption microbalance. The results obtained indicated that in addition to the concentration of surface-attached amino groups, specific interactions between CO(2) and the surface amino groups, and the resultant pore structure after amine group attachment have a significant impact on CO(2) adsorption properties of these promising adsorbent materials.

Prediction of meningococcal meningitis epidemics in western Africa by using climate information

NASA Astrophysics Data System (ADS)

YAKA, D. P.; Sultan, B.; Tarbangdo, F.; Thiaw, W. M.

2013-12-01

The variations of certain climatic parameters and the degradation of ecosystems, can affect human's health by influencing the transmission, the spatiotemporal repartition and the intensity of infectious diseases. It is mainly the case of meningococcal meningitis (MCM) whose epidemics occur particularly in Sahelo-Soudanian climatic area of Western Africa under quite particular climatic conditions. Meningococcal Meningitis (MCM) is a contagious infection disease due to the bacteria Neisseria meningitis. MCM epidemics occur worldwide but the highest incidence is observed in the "meningitis belt" of sub-Saharan Africa, stretching from Senegal to Ethiopia. In spite of standards, strategies of prevention and control of MCS epidemic from World Health Organization (WHO) and States, African Sahelo-Soudanian countries remain frequently afflicted by disastrous epidemics. In fact, each year, during the dry season (February-April), 25 to 250 thousands of cases are observed. Children under 15 are particularly affected. Among favourable conditions for the resurgence and dispersion of the disease, climatic conditions may be important inducing seasonal fluctuations in disease incidence and contributing to explain the spatial pattern of the disease roughly circumscribed to the ecological Sahelo-Sudanian band. In this study, we tried to analyse the relationships between climatic factors, ecosystems degradation and MCM for a better understanding of MCM epidemic dynamic and their prediction. We have shown that MCM epidemics, whether at the regional, national or local level, occur in a specific period of the year, mainly from January to May characterised by a dry, hot and sandy weather. We have identified both in situ (meteorological synoptic stations) and satellitales climatic variables (NCEP reanalysis dataset) whose seasonal variability is dominating in MCM seasonal transmission. Statistical analysis have measured the links between seasonal variation of certain climatic parameters (particularly the meridional wind components) and seasonal recrudescence of MCM cases in order to elaborate seasonal occurrence of MCM epidemics prediction models on different spatiotemporal scales. These predictions have been experienced and evaluated by Burkina Meteorological Authority and Health Protection General Direction since 2009. The encouraging results from the monitoring and evaluation of these predictions given by such simple models enable the development of a monitoring and an early warning integrated system of MCM epidemics in Burkina Faso. This experience could be implemented in others African Sahelo-Soudanian countries.

Thermal management and light extraction in multi-chip and high-voltage LEDs by cup-shaped copper heat spreader technology

NASA Astrophysics Data System (ADS)

Horng, Ray-Hua; Hu, Hung-Lieh; Tang, Li-Shen; Ou, Sin-Liang

2013-03-01

For LEDs with original structure and copper heat spreader, the highest surface temperatures of 3×3 array LEDs modules were 52.6 and 42.67 °C (with 1050 mA injection current), while the highest surface temperatures of 4×4 array LEDs modules were 58.55 and 48.85 °C (with 1400 mA injection current), respectively. As the 5×5 array LEDs modules with original structure and copper heat spreader were fabricated, the highest surface temperatures at 1750 mA injection current were 68.51 and 56.73 °C, respectively. The thermal resistance of optimal LEDs array module with copper heat spreader on heat sink using compound solder is reduced obviously. On the other hand, the output powers of 3×3, 4×4 and 5×5 array LEDs modules with original structure were 3621.7, 6346.3 and 9760.4 mW at injection currents of 1050, 1400 and 1750 mA, respectively. Meanwhile, the output powers of these samples with copper heat spreader can be improved to 4098.5, 7150.3 and 10919.6 mW, respectively. The optical and thermal characteristics of array LEDs module have been improved significantly using the cup-shaped copper structure. Furthermore, various types of epoxy-packaged LEDs with cup-shaped structure were also fabricated. It is found that the light extraction efficiency of LED with semicircle package has 55% improvement as compared to that of LED with flat package. The cup-shaped copper structure was contacted directly with sapphire to enhance heat dissipation. In addition to efficient heat dissipation, the light extraction of the lateral emitting in high-power LEDs can be improved.

Enhanced electrochemiluminescence sensor from tris(2,2'-bipyridyl)ruthenium(II) incorporated into MCM-41 and an ionic liquid-based carbon paste electrode.

PubMed

Li, Jing; Huang, Minghua; Liu, Xiaoqing; Wei, Hui; Xu, Yuanhong; Xu, Guobao; Wang, Erkang

2007-07-01

The electrochemiluminescence (ECL) of tris(2,2'-bipyridyl)ruthenium(II) [Ru(bpy)(3)(2+)] ion-exchanged in the sulfonic-functionalized MCM-41 silicas was developed with tripropylamine (TPrA) as a co-reactant in a carbon paste electrode (CPE) using a room temperature ionic liquid (IL) as a binder. The sulfonic-functionalized silicas MCM-41 were used for preparing an ECL sensor by the electrostatic interactions between Ru(bpy)(3)(2+) cations and sulfonic acid groups. We used the IL as a binder to construct the CPE (IL-CPE) to replace the traditional binder of the CPE (T-CPE)--silicone oil. The results indicated that the MCM-41-modified IL-CPE had more open structures to allow faster diffusion of Ru(bpy)(3)(2+) and that the ionic liquid also acted as a conducting bridge to connect TPrA with Ru(bpy)(3)(2+) sites immobilized in the electrode, resulting in a higher ECL intensity compared with the MCM-41-modified T-CPE. Herein, the detection limit for TPrA of the MCM-41-modified IL-CPE was 7.2 nM, which was two orders of magnitude lower than that observed at the T-CPE. When this new sensor was used in flow injection analysis (FIA), the MCM-41-modified IL-CPE ECL sensor also showed good reproducibility. Furthermore, the sensor could also be renewed easily by mechanical polishing whenever needed.

Cdc45 (cell division cycle protein 45) guards the gate of the Eukaryote Replisome helicase stabilizing leading strand engagement

PubMed Central

Petojevic, Tatjana; Pesavento, James J.; Costa, Alessandro; Liang, Jingdan; Wang, Zhijun; Berger, James M.; Botchan, Michael R.

2015-01-01

DNA replication licensing is now understood to be the pathway that leads to the assembly of double hexamers of minichromosome maintenance (Mcm2–7) at origin sites. Cell division control protein 45 (Cdc45) and GINS proteins activate the latent Mcm2–7 helicase by inducing allosteric changes through binding, forming a Cdc45/Mcm2-7/GINS (CMG) complex that is competent to unwind duplex DNA. The CMG has an active gate between subunits Mcm2 and Mcm5 that opens and closes in response to nucleotide binding. The consequences of inappropriate Mcm2/5 gate actuation and the role of a side channel formed between GINS/Cdc45 and the outer edge of the Mcm2–7 ring for unwinding have remained unexplored. Here we uncover a novel function for Cdc45. Cross-linking studies trace the path of the DNA with the CMG complex at a fork junction between duplex and single strands with the bound CMG in an open or closed gate conformation. In the closed state, the lagging strand does not pass through the side channel, but in the open state, the leading strand surprisingly interacts with Cdc45. Mutations in the recombination protein J fold of Cdc45 that ablate this interaction diminish helicase activity. These data indicate that Cdc45 serves as a shield to guard against occasional slippage of the leading strand from the core channel. PMID:25561522

MCM-2 expression differentiates potentially malignant verrucous lesions from oral carcinomas.

PubMed

Niranjan, Kochli Channappa; Sarathy, Niharika Abhay; Alrani, Devendra

2018-03-13

Mcm-2 is a biomarker belonging to Mcm family of proteins which has rarely been used in oral potentially malignant and malignant lesions of the verrucous type. The objective of this study is to assess the expression of Mcm-2 in Normal Oral Mucosa (NM), Verrucous Hyperplasia (VH), Verrucous Carcinoma (VC) and Oral Squamous Cell Carcinoma (OSCC) and compare it with the clinicopathological characteristics. A total of 70 formalin fixed paraffin embedded tissue samples (10 cases of Normal Mucosa NM- Group A, 10 cases of Verrucous Hyperplasia- VH without Dysplasia- Group B, 10 cases of Verrucous Hyperplasia- VH with Dysplasia- Group C, 20 cases of Verrucous Carcinoma VC-Group D, 20 cases of Oral Squamous Cell Carcinoma OSCC- Group E) were subjected to immunohistochemistry with Mcm-2 antibody. Statistical analysis was carried out with various tests like ANOVA, Tukey HSD, Chi-Square and Shapiro-Wilk test by using the SPSS software. There was a significant difference in Mcm-2 expression with quantitative analysis among all the groups (p < 0.05). There was a significant progressive increase in nuclear Labelling Indices (nLI) from NM (49.08%), VC (60.45%), VH with Dysplasia (64.10%), and OSCC (89.22%). The findings suggest that Mcm-2 may be a sensitive proliferation marker in oral potentially malignant and malignant lesions which may be useful for differentiating between VH with/ without dysplasia, VC and OSCC. Copyright © 2018. Published by Elsevier Inc.

Functionalized bimodal mesoporous silicas as carriers for controlled aspirin delivery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao Lin; Sun Jihong, E-mail: jhsun@bjut.edu.cn; Li Yuzhen

The bimodal mesoporous silica modified with 3-aminopropyltriethoxysilane was performed as the aspirin carrier. The samples' structure, drug loading and release profiles were characterized with X-ray diffraction, scanning electron microscopy, N{sub 2} adsorption and desorption, Fourier transform infrared spectroscopy, TG analysis, elemental analysis and UV-spectrophotometer. For further exploring the effects of the bimodal mesopores on the drug delivery behavior, the unimodal mesoporous material MCM-41 was also modified as the aspirin carrier. Meantime, Korsmeyer-Peppas equation f{sub t}=kt{sup n} was employed to analyze the dissolution data in details. It is indicated that the bimodal mesopores are beneficial for unrestricted drug molecules diffusing andmore » therefore lead to a higher loading and faster releasing than that of MCM-41. The results show that the aspirin delivery properties are influenced considerably by the mesoporous matrix, whereas the large pore of bimodal mesoporous silica is the key point for the improved controlled-release properties. - Graphical abstract: Loading (A) and release profiles (B) of aspirin in N-BMMs and N-MCM-41 indicated that BMMs have more drug loading capacity and faster release rate than that MCM-41. Highlights: > Bimodal mesoporous silicas (BMMs) and MCM-41 modified with amino group via post-treatment procedure. > Loading and release profiles of aspirin in modified BMMs and MCM-41. > Modified BMMs have more drug loading capacity and faster release rate than that modified MCM-41.« less

Synthesis and application of Pb-MCM-41/ZnNiO2 as a novel mesoporous nanocomposite adsorbent for the decontamination of chloroethyl phenyl sulfide (CEPS)

NASA Astrophysics Data System (ADS)

Sadeghi, Meysam; Yekta, Sina; Ghaedi, Hamed

2017-04-01

In the current research, MCM-41 was successfully prepared by the sol-gel method and lead ions (Pb2+) were loaded in the synthesized MCM-41 mesoporous structure to prepare Pb-MCM-41. The ZnO-NiO nanoparticles (ZnNiO2 NPs) as a type of bimetallic oxides were then dispersed and deposited on the surface of Pb-MCM-41 through indirect method to gain the final Pb-MCM-41/ZnNiO2 nanocomposite adsorbent. The characterization study of samples carried out by SEM-EDAX, AFM, XRD and FTIR techniques. Pb-MCM-41/ZnNiO2 nanocomposite as a destructive adsorbent has been proposed for the first time for the decontamination process of chloroethyl phenyl sulfide (CEPS), a mimic of bis(chloroethyl) sulfide (i.e. sulfur mustard), and were confirmed using GC-FID, GC-MS and FTIR instruments. Besides, the effect of different experimental parameters including contact time, catalyst dose and initial concentration of CEPS on the decontamination efficiency of this agent simulant were also perused. The GC-FID analysis results verified that the maximum decontamination of CEPS was more than 90% yield. The parameters such as: contact time (240 min), adsorbent dose (0.4 g/L), and initial concentration (10 mg/L) were investigated and considered as optimized conditions for the noted reaction. Moreover, the reaction kinetic information was surveyed by employing first order model. The values of the rate constant (k) and half-life (t1/2) were determined as 0.0128 min-1 and 54.1406 min, and 0.0012 min-1 and 577.5 min for CEPS and its hydrolysis/elimination products, respectively. Data demonstrates the role of the hydrolysis and elimination products, i.e. hydroxy ethyl phenyl sulfide (HEPS) and phenyl vinyl sulfide (PVS) in the reaction of CEPS with Pb-MCM-41/ZnNiO2 nanocomposite and GC-MS analysis was exerted to identify and quantify simulant destruction products. It was clarified that Pb-MCM-41/ZnNiO2 nanocomposite gains a high capacity and potential for the effective decontamination of CEPS.

Steam stable mesoporous silica MCM-41 stabilized by trace amounts of Al.

PubMed

Tompkins, Jordan T; Mokaya, Robert

2014-02-12

Evaluation of low and ultralow Al content (Si/Al between 50 and 412) aluminosilicate Al-MCM-41 materials synthesized via three contrasting alumination routes, namely, direct mixed-gel synthesis, post-synthesis wet grafting, and post-synthesis dry grafting, indicates that trace amounts of Al introduced via dry grafting can stabilize mesoporous silica MCM-41 to steaming at 900 °C for 4 h. It was found that trace amounts of Al (Si/Al > 400) introduced via so-called dry grafting of Al stabilize the virtually purely siliceous MCM-41 to steaming, whereas Al incorporated via other methods that involve aqueous media such as direct mixed gel synthesis or wet grafting of Al offer only limited protection at low Al content. It is particularly remarkable that a post-synthesis dry grafted Al-MCM-41 material possessing trace amounts of Al (i.e., Si/Al ratio of 412) and surface area and pore volume of 1112 m(2)/g and 1.20 cm(3)/g, respectively, retains 90% (998 m(2)/g) of the surface area and 85% (1.03 cm(3)/g) of the pore volume after exposure to steaming at 900 °C for 4 h. Under similar steam treatment conditions, the mesostructure of pure silica Si-MCM-41 is virtually destroyed and undergoes a 93% reduction in surface area (958 m(2)/g to 69 m(2)/g) and 88% decrease in pore volume (0.97 cm(3)/g to 0.12 cm(3)/g). The steam stable ultralow (i.e., trace) Al containing MCM-41 materials is found to be virtually similar to mesoporous pure silica Si-MCM-41 with hardly any detectable acidity. The improvement in steam stability arises from not only the presence of trace amounts of Al, but also from an apparent increase in the level of silica condensation that is specific to dry grafted alluminosilicate MCM-41 materials. The more highly condensed framework has fewer silanol groups and therefore is more resistant to hydrolysis under steaming conditions.

The haloarchaeal MCM proteins: bioinformatic analysis and targeted mutagenesis of the β7-β8 and β9-β10 hairpin loops and conserved zinc binding domain cysteines

PubMed Central

Kristensen, Tatjana P.; Maria Cherian, Reeja; Gray, Fiona C.; MacNeill, Stuart A.

2014-01-01

The hexameric MCM complex is the catalytic core of the replicative helicase in eukaryotic and archaeal cells. Here we describe the first in vivo analysis of archaeal MCM protein structure and function relationships using the genetically tractable haloarchaeon Haloferax volcanii as a model system. Hfx. volcanii encodes a single MCM protein that is part of the previously identified core group of haloarchaeal MCM proteins. Three structural features of the N-terminal domain of the Hfx. volcanii MCM protein were targeted for mutagenesis: the β7-β8 and β9-β10 β-hairpin loops and putative zinc binding domain. Five strains carrying single point mutations in the β7-β8 β-hairpin loop were constructed, none of which displayed impaired cell growth under normal conditions or when treated with the DNA damaging agent mitomycin C. However, short sequence deletions within the β7-β8 β-hairpin were not tolerated and neither was replacement of the highly conserved residue glutamate 187 with alanine. Six strains carrying paired alanine substitutions within the β9-β10 β-hairpin loop were constructed, leading to the conclusion that no individual amino acid within that hairpin loop is absolutely required for MCM function, although one of the mutant strains displays greatly enhanced sensitivity to mitomycin C. Deletions of two or four amino acids from the β9-β10 β-hairpin were tolerated but mutants carrying larger deletions were inviable. Similarly, it was not possible to construct mutants in which any of the conserved zinc binding cysteines was replaced with alanine, underlining the likely importance of zinc binding for MCM function. The results of these studies demonstrate the feasibility of using Hfx. volcanii as a model system for reverse genetic analysis of archaeal MCM protein function and provide important confirmation of the in vivo importance of conserved structural features identified by previous bioinformatic, biochemical and structural studies. PMID:24723920

MCM: one ring to rule them all.

PubMed

Deegan, Tom D; Diffley, John F X

2016-04-01

Precise replication of the eukaryotic genome is achieved primarily through strict regulation of the enzyme responsible for DNA unwinding, the replicative helicase. The motor of this helicase is a hexameric AAA+ ATPase called MCM. The loading of MCM onto DNA and its subsequent activation and disassembly are each restricted to separate cell cycle phases; this ensures that a functional replisome is only built once at any replication origin. In recent years, biochemical and structural studies have shown that distinct conformational changes in MCM, each requiring post-translational modifications and/or the activity of other replication proteins, define the various stages of the chromosome replication cycle. Here, we review recent progress in this area. Copyright © 2016. Published by Elsevier Ltd.

Synthesis, Characterization and Application of N-Ti/13X/MCM-41 Mesoporous Molecular Sieves.

PubMed

Tao, Hong; Nguyen, Nhat-Thien; Hei, Xiao-Hui; Nguyen, Cong Nguyen; Tsai, Hsiao-Hsin; Chang, I-Cheng; Chang, Chang-Tang

2016-06-01

Di-n-butyl phthalate (DBP) is a type of phthalate ester. In recent years, an increasing number of studies have examined the removal of DBP. In this study we use a composite material of N-Ti/13X/MCM-41, synthesized by nitrogen, molecular sieve 13X, tetrabutyl orthotitanate and tetraethyl orthosilicate as raw materials, CTAB as a structural template and tetrabutyl titanate and urea under hydrothermal conditions. The optimized experimental conditions, such as the amount of material, reaction time, pH value and initial concentration were tested. The surface areas of N-Ti/13X/MCM-41 were found to be 664 m2g(-1). TEM micrographs revealed N-Ti/13X/MCM-41 is consisting of aggregates of spherical particles, similar with standard synthesized MCM-41 (Mobil Composition of Matter No. 41). Through photocatalytic degradation experiments, the optimum degradation efficiency of DBP was more than 90% at a pH 6.0 with catalyst dosing of 0.15 g L(-1).

How and why multiple MCMs are loaded at origins of DNA replication.

PubMed

Das, Shankar P; Rhind, Nicholas

2016-07-01

Recent work suggests that DNA replication origins are regulated by the number of multiple mini-chromosome maintenance (MCM) complexes loaded. Origins are defined by the loading of MCM - the replicative helicase which initiates DNA replication and replication kinetics determined by origin's location and firing times. However, activation of MCM is heterogeneous; different origins firing at different times in different cells. Also, more MCMs are loaded in G1 than are used in S phase. These aspects of MCM biology are explained by the observation that multiple MCMs are loaded at origins. Having more MCMs at early origins makes them more likely to fire, effecting differences in origin efficiency that define replication timing. Nonetheless, multiple MCM loading raises new questions, such as how they are loaded, where these MCMs reside at origins, and how their presence affects replication timing. In this review, we address these questions and discuss future avenues of research. © 2016 WILEY Periodicals, Inc.

A MADS box protein interacts with a mating-type protein and is required for fruiting body development in the homothallic ascomycete Sordaria macrospora.

PubMed

Nolting, Nicole; Pöggeler, Stefanie

2006-07-01

MADS box transcription factors control diverse developmental processes in plants, metazoans, and fungi. To analyze the involvement of MADS box proteins in fruiting body development of filamentous ascomycetes, we isolated the mcm1 gene from the homothallic ascomycete Sordaria macrospora, which encodes a putative homologue of the Saccharomyces cerevisiae MADS box protein Mcm1p. Deletion of the S. macrospora mcm1 gene resulted in reduced biomass, increased hyphal branching, and reduced hyphal compartment length during vegetative growth. Furthermore, the S. macrospora Deltamcm1 strain was unable to produce fruiting bodies or ascospores during sexual development. A yeast two-hybrid analysis in conjugation with in vitro analyses demonstrated that the S. macrospora MCM1 protein can interact with the putative transcription factor SMTA-1, encoded by the S. macrospora mating-type locus. These results suggest that the S. macrospora MCM1 protein is involved in the transcriptional regulation of mating-type-specific genes as well as in fruiting body development.

The Interaction between Checkpoint Kinase 1 (Chk1) and the Minichromosome Maintenance (MCM) Complex Is Required for DNA Damage-induced Chk1 Phosphorylation*

PubMed Central

Han, Xiangzi; Aslanian, Aaron; Fu, Kang; Tsuji, Toshiya; Zhang, Youwei

2014-01-01

Chk1 is an essential mediator of the DNA damage response and cell cycle checkpoint. However, how exactly Chk1 transduces the checkpoint signaling is not fully understood. Here we report the identification of the heterohexamic minichromosome maintenance (MCM) complex that interacts with Chk1 by mass spectrometry. The interaction between Chk1 and the MCM complex was reduced by DNA damage treatment. We show that the MCM complex, at least partially, contributes to the chromatin association of Chk1, allowing for immediate phosphorylation of Chk1 by ataxia telangiectasia mutated and Rad3-related (ATR) in the presence of DNA damage. Further, phosphorylation of Chk1 at ATR sites reduces the interaction between Chk1 and the MCM complex, facilitating chromatin release of phosphorylated Chk1, a critical step in the initiation and amplification of cell cycle checkpoint. Together, these data provide novel insights into the activation of Chk1 in response to DNA damage. PMID:25049228

Analysis of the crystal structure of an active MCM hexamer.

PubMed

Miller, Justin M; Arachea, Buenafe T; Epling, Leslie B; Enemark, Eric J

2014-09-29

In a previous Research article (Froelich et al., 2014), we suggested an MCM helicase activation mechanism, but were limited in discussing the ATPase domain because it was absent from the crystal structure. Here we present the crystal structure of a nearly full-length MCM hexamer that is helicase-active and thus has all features essential for unwinding DNA. The structure is a chimera of Sulfolobus solfataricus N-terminal domain and Pyrococcus furiosus ATPase domain. We discuss three major findings: 1) a novel conformation for the A-subdomain that could play a role in MCM regulation; 2) interaction of a universally conserved glutamine in the N-terminal Allosteric Communication Loop with the AAA+ domain helix-2-insert (h2i); and 3) a recessed binding pocket for the MCM ssDNA-binding motif influenced by the h2i. We suggest that during helicase activation, the h2i clamps down on the leading strand to facilitate strand retention and regulate ATP hydrolysis.

Synthesis of ZnO-CuO/MCM-48 photocatalyst for the degradation of organic pollutions.

PubMed

Duan, Yongzheng; Shen, Yulian

2017-07-01

The photocatalytic properties of ZnO-CuO catalysts supported on siliceous MCM-48 (Mobil Composition of Matter No. 48) for the degradation of organic pollutions such as methylene blue and salicylic acid under UV light irradiation were investigated. These catalysts were prepared by impregnation of MCM-48 with a mixed aqueous solution of copper acetate and zinc acetate. X-ray diffraction, N 2 -physisorption, high resolution transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and photoluminescence were used to characterize these samples. Results from characterizations showed that the addition of ZnO to CuO/MCM-48 could markedly improve the photocatalytic degradation properties. The enhanced photocatalytic behaviors of ZnO-CuO/MCM-48 may be due to the formation of p-n heterojunctions between ZnO and CuO, resulting in the effective separation of photogenerated electron-hole pairs. Moreover, the photocatalysts were easily recovered and reused for five cycles without considerable loss of activity.

[A morphometric analysis of the nuclei and nucleoli in tumor cells in lymphogranulomatosis, diffuse large B-cell lymphoma and anaplastic large cell lymphoma].

PubMed

Gorgidze, L A; Vorob'ev, I A

2009-01-01

To make a comparative morphometric analysis of the nuclei and nucleoli of tumor cells in lymphogranulomatosis (LGM), diffuse large B-cell lymphoma (DLBCL) and anaplastic large cell lymphoma (ALCL) for differential diagnosis of these lymphomas. Biopsy material (lymph node biopsies) was frozen in hexane, fixed and stained, then microscopic pictures were made. Mean area of tumor cell nuclei in LGM was 97.25 +/- 68.77 mcm2, in DLBCL and ALCL--55.89 +/- 20.13 mcm2 and 70.31 +/- 34.64 mcm2, respectively. The area differences were significant (p < 0.001). Hodgkin's and Berezovsky-Rid-Sternberg cell bucleoli area was the largest (11.44 +/- 7.83 mcm2). The nucleoli of the former are larger than those of the latter. Mean area of the nucleoli in DLBCL was 3.05 +/- 1.58, in ALCL--5.53 +/- 4.94 mcm2. The differences are significant (p < 0.001). Nucleoli in Hodgkin 's cells are significantly larger than those in the tumor cells in ALCL and DLBCL and the nucleoli with the area more than 12 mcm2 can be used in differential diagnosis between LGM and DLBCL but not between LGM and ALCL.

High sensitivity of gold nanoparticles co-doped with Gd2O3 mesoporous silica nanocomposite to nasopharyngeal carcinoma cells

NASA Astrophysics Data System (ADS)

Wang, Hui; Zhang, Songjin; Tian, Xiumei; Liu, Chufeng; Zhang, Lei; Hu, Wenyong; Shao, Yuanzhi; Li, Li

2016-10-01

Nanoprobes for combined optical and magnetic resonance imaging have tremendous potential in early cancer diagnosis. Gold nanoparticles (AuNPs) co-doped with Gd2O3 mesoporous silica nanocomposite (Au/Gd@MCM-41) can produce pronounced contrast enhancement for T1 weighted image in magnetic resonance imaging (MRI). Here, we show the remarkably high sensitivity of Au/Gd@MCM-41 to the human poorly differentiated nasopharyngeal carcinoma (NPC) cell line (CNE-2) using fluorescence lifetime imaging (FLIM). The upconversion luminescences from CNE-2 and the normal nasopharyngeal (NP) cells (NP69) after uptake of Au/Gd@MCM-41 show the characteristic of two-photon-induced-radiative recombination of the AuNPs. The presence of the Gd3+ ion induces a much shorter luminescence lifetime in CNE-2 cells. The interaction between AuNPs and Gd3+ ion clearly enhances the optical sensitivity of Au/Gd@MCM-41 to CNE-2. Furthermore, the difference in the autofluorescence between CNE-2 and NP69 cells can be efficiently demonstrated by the emission lifetimes of Au/Gd@MCM-41 through the Forster energy transfers from the endogenous fluorophores to AuNPs. The results suggest that Au/Gd@MCM-41 may impart high optical resolution for the FLIM imaging that differentiates normal and high-grade precancers.

Ultrasonic-assisted synthesis of novel nanocomposite of poly(vinyl alcohol) and amino-modified MCM-41: A green adsorbent for Cd(II) removal.

PubMed

Soltani, Roozbeh; Dinari, Mohammad; Mohammadnezhad, Gholamhossein

2018-01-01

Amino-modified MCM-41/poly(vinyl alcohol) nanocomposite (M-MCM-41/PVOH NC) was developed for the adsorption of Cd(II) from aqueous media. M-MCM-41/PVOH NC was prepared through ultrasonic-assisted and simple blending procedure with economical and environmentally friendly polymer. The as-prepared adsorbent was characterized by FT-IR, TEM, FE-SEM and TGA. The contact time, solution pH and initial concentration of Cd(II) were found to affect the adsorption of Cd(II) from aqueous media. Kinetic studies were carried out and pseudo-first-order (PFO), pseudo-second-order (PSO), Elovich, and intra-particle diffusion (IPD) reaction kinetic models were examined. The kinetic results revealed that the adsorption of Cd(II) onto M-MCM-41/PVOH NC followed PSO kinetic model and is a chemical adsorption. The equilibrium adsorption data were evaluated by different isotherms viz. Langmuir, Freundlich, and Dubinin Radushkevich (D-R) equations. The equilibrium data fitted better with the Langmuir isotherm and the maximum adsorption capacity of M-MCM-41/PVOH NC at 298K was calculated to be 46.73mgg -1 for Cd(II) on a typical saturated monomolecular layer with a fixed number of localized adsorption sites. Copyright © 2017 Elsevier B.V. All rights reserved.

Alcohols react with MCM-41 at room temperature and chemically modify mesoporous silica.

PubMed

Björklund, Sebastian; Kocherbitov, Vitaly

2017-08-30

Mesoporous silica has received much attention due to its well-defined structural order, high surface area, and tunable pore diameter. To successfully employ mesoporous silica for nanotechnology applications it is important to consider how it is influenced by solvent molecules due to the fact that most preparation procedures involve treatment in various solvents. In the present work we contribute to this important topic with new results on how MCM-41 is affected by a simple treatment in alcohol at room temperature. The effects of alcohol treatment are characterized by TGA, FTIR, and sorption calorimetry. The results are clear and show that treatment of MCM-41 in methanol, ethanol, propanol, butanol, pentanol, or octanol at room temperature introduces alkoxy groups that are covalently bound to the silica surface. It is shown that alcohol treated MCM-41 becomes more hydrophobic and that this effect is sequentially more prominent going from methanol to octanol. Chemical formation of alkoxy groups onto MCM-41 occurs both for calcined and hydroxylated MCM-41 and the alkoxy groups are hydrolytically unstable and can be replaced by silanol groups after exposure to water. The results are highly relevant for mesoporous silica applications that involve contact or treatment in protic solvents, which is very common.

Grafting of [(64)Cu]-TPPF20 porphyrin complex on Functionalized nano-porous MCM-41 silica as a potential cancer imaging agent.

PubMed

Fazaeli, Yousef; Feizi, Shahzad; Jalilian, Amir R; Hejrani, Ali

2016-06-01

Mesoporous silica, MCM-41, functionalized with 3-aminopropyltriethoxysilane (APTES) was investigated as a potential drug delivery system, using [(64)Cu]-5, 10, 15, 20-tetrakis penta fluorophenyl porphyrin complex. [(64)Cu]-TPPF20 complex was grafted on functionalized MCM-41. The product was characterized by paper chromatography, FTIR spectroscopy, low angle X-ray diffraction, CHN and TGA/DTA analyses and atomic force microscopy. The biological evaluations of the grafted complex, [(64)Cu]-TPPF20@NH2-MCM-41, were done in Fibrosarcoma tumor-bearing Sprague-Dawley rats using scarification studies and Sopha DST-XL Dual-Head SPECT system. The actual loading amount of aminopropyl groups was found about 1.6mmol per gram of final silica. The specific activity of the final compound was found to be 3Ci/g. Amine functionalized MCM-41 was found to be a good platform for theranostic radiopharmaceuticals such as copper-64 complexes. Considering the accumulation of the tracer in tumor cells, fast wash-out from normal tissues, the short half-life copper-64 and less imposed radiation doses to patients, [(64)Cu]-TPPF20@NH2-MCM-41 can potentially be a suitable candidate for tumor imaging applications and future PET studies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of MCM09, an active site-directed inhibitor of factor Xa, on B16-BL6 melanoma lung colonies in mice.

PubMed

Rossi, C; Hess, S; Eckl, R W; di Lena, A; Bruno, A; Thomas, O; Poggi, A

2006-03-01

Treatment with anticoagulant drugs has shown potential inhibitory effect on tumor invasion, although the relationship with clotting inhibition was not clear. The aim of our study was to evaluate the potential antitumor activity of MCM09, a newly developed, active site-directed, small molecule inhibitor of factor Xa (FXa) [WO0216312], and to relate the findings to anticlotting potency. MCM09 (0.1-10 mg kg(-1)) or heparin (H; 10 mg kg(-1)) was injected intravenously (i.v.), with 5 x 10(4) B16-BL6 melanoma cells, in C57BL/6 mice. Mice were killed after 18 days, to count lung colonies. Ex vivo anticoagulant activity was measured by activated partial thromboplastin time (APTT) on mouse plasma. MCM09, a selective inhibitor of FXa (IC-50 = 2.4 nm against human FXa), inhibited in a dose-dependent manner B16-BL6 melanoma lung colonies in mice. Mean lung metastasis number was 20.9 +/- 4.8 in controls (n = 10), 1.2 +/- 0.4 in mice treated with H, 10 mg kg(-1) i.v. (P < 0.01), 0.9 +/- 0.3, 9.2 +/- 2.2 and 15.5 +/- 2.6 in mice treated with MCM09, at 10 (P < 0.01), 1 (P < 0.05) and 0.1 mg kg(-1) i.v. (ns), respectively. MCM09 (10 mg kg(-1) i.v.) significantly prolonged APTT (57.1 +/- 10.2 s) 30 min after i.v. injection when compared with controls (25.3 +/- 1.6 s; P < 0.05). Lung colonies were 74.2-72.6% reduced by MCM09 (10 mg kg(-1)) given 60 or 120 min before cells, but not by MCM09 given 60 min thereafter, suggesting a direct cell interaction as a mechanism underlying antitumor activity.

Ordered cubic nanoporous silica support MCM-48 for delivery of poorly soluble drug indomethacin

NASA Astrophysics Data System (ADS)

Zeleňák, Vladimír; Halamová, Dáša; Almáši, Miroslav; Žid, Lukáš; Zeleňáková, Adriána; Kapusta, Ondrej

2018-06-01

Ordered MCM-48 nanoporous silica (SBET = 923(3) m2·g-1, VP = 0.63(2) cm3·g-1) with cubic Ia3d symmetry was used as a support for drug delivery of anti-inflammatory poorly soluble drug indomethacin. The delivery from parent, unmodified MCM-48, and 3-aminopropyl modified silica carrier was studied into the simulated body fluids with the pH = 2 and pH = 7.4. The studied samples were characterized by thermal analysis (TG/DTG-DTA), N2 adsorption/desorption, infrared spectroscopy (FT-IR), powder XRD, SEM, HRTEM methods, measurements of zeta potential (ζ) and dynamic light scattering (DLS). The determined content of indomethacin in pure MCM-48 was 21 wt.% and in the amine-modified silica MCM-48A-I the content was 45 wt.%. The release profile of the drug, in the time period up to 72 h, was monitored by TLC chromatographic method. It as shown, that by the modification of the surface, the drug release can be controlled. The slower release of indomethacin was observed from amino modified sample MCM-48A-I in the both types of studied simulated body fluids (slightly alkaline intravenous solution with pH = 7.4 and acidic gastric fluid with pH = 2), which was supported and explained by zeta potential and DLS measurements. The amount of the released indomethacin into the fluids with various pH was different. The maximum released amount of the drug was 97% for sample containing unmodified silica, MCM-48-I at pH = 7.4 and lowest released amount, 57%, for amine modified sample MCM-48A-I at pH = 2. To compare the indomethacin release profile four kinetic models were tested. Results showed, that that the drug release based on diffusion Higuchi model, mainly governs the release.

Rapid synthesis of Ti-MCM-41 by microwave-assisted hydrothermal method towards photocatalytic degradation of oxytetracycline.

PubMed

Chen, Hanlin; Peng, Yen-Ping; Chen, Ku-Fan; Lai, Chia-Hsiang; Lin, Yung-Chang

2016-06-01

This study employed microwave-assisted hydrothermal method to synthesize Ti-MCM-41, which are mesoporous materials with a high surface area and excellent photocatalytic ability. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and ultraviolet-visible spectroscopy (UV-Vis) were employed. The XRD findings showed that Ti-MCM-41 exhibited a peak at 2θ of 2.2°, which was attributed to the hexagonal MCM-41 structure. The BET (Brunauer-Emmett-Teller) results agreed with the TEM findings that Ti-MCM-41 has a pore size of about 3-5nm and a high surface area of 883m(2)/g. FTIR results illustrated the existence of Si-O-Si and Si-O-Ti bonds in Ti-MCM-41. The appearance of Ti 2p peaks in the XPS results confirmed the FTIR findings that the Ti was successfully doped into the MCM-41 structure. Zeta (ζ)-potential results indicated that the iso-electric point (IEP) of Ti-MCM-41 was at about pH3.02. In this study, the photocatalytic degradation of oxytetracycline (OTC) at different pH was investigated under Hg lamp irradiation (wavelength 365nm). The rate constant (K'obs) for OTC degradation was 0.012min(-1) at pH3. Furthermore, TOC (total organic carbon) and high resolution LC-MS (liquid chromatography-mass spectrometry) analyses were conducted to elucidate the possible intermediate products and degradation pathway for OTC. The TOC removal efficiency of OTC degradation was 87.0%, 74.4% and 50.9% at pH3, 7 and 10, respectively. LC-MS analysis results showed that the degradation products from OTC resulted from the removal of functional groups from the OTC ring. Copyright © 2016. Published by Elsevier B.V.

Temperature-dependent photoluminescence in meso-porous MCM nanotubes

NASA Astrophysics Data System (ADS)

Lee, Y. C.; Liu, Y. L.; Lee, W. Z.; Wang, C. K.; Shen, J. L.; Cheng, P. W.; Cheng, C. F.; Lin, T. Y.

2004-11-01

Temperature-dependent photoluminescence (PL) was exploited to investigate the mechanism of luminescence of MCM (Mobil Composition of Matter)-41 and MCM-48 nanotubes. The PL intensity has a maximum around 40 K. Localization of the carriers involved in the radiative recombination was deduced from the PL decay profiles at various energies. A model based on competition between radiative recombination of localized carriers and nonradiative recombination is suggested to explain the temperature-dependence of PL intensity.

Universal sensor interface module (USIM)

NASA Astrophysics Data System (ADS)

King, Don; Torres, A.; Wynn, John

1999-01-01

A universal sensor interface model (USIM) is being developed by the Raytheon-TI Systems Company for use with fields of unattended distributed sensors. In its production configuration, the USIM will be a multichip module consisting of a set of common modules. The common module USIM set consists of (1) a sensor adapter interface (SAI) module, (2) digital signal processor (DSP) and associated memory module, and (3) a RF transceiver model. The multispectral sensor interface is designed around a low-power A/D converted, whose input/output interface consists of: -8 buffered, sampled inputs from various devices including environmental, acoustic seismic and magnetic sensors. The eight sensor inputs are each high-impedance, low- capacitance, differential amplifiers. The inputs are ideally suited for interface with discrete or MEMS sensors, since the differential input will allow direct connection with high-impedance bridge sensors and capacitance voltage sources. Each amplifier is connected to a 22-bit (Delta) (Sigma) A/D converter to enable simultaneous samples. The low power (Delta) (Sigma) converter provides 22-bit resolution at sample frequencies up to 142 hertz (used for magnetic sensors) and 16-bit resolution at frequencies up to 1168 hertz (used for acoustic and seismic sensors). The video interface module is based around the TMS320C5410 DSP. It can provide sensor array addressing, video data input, data calibration and correction. The processor module is based upon a MPC555. It will be used for mode control, synchronization of complex sensors, sensor signal processing, array processing, target classification and tracking. Many functions of the A/D, DSP and transceiver can be powered down by using variable clock speeds under software command or chip power switches. They can be returned to intermediate or full operation by DSP command. Power management may be based on the USIM's internal timer, command from the USIM transceiver, or by sleep mode processing management. The low power detection mode is implemented by monitoring any of the sensor analog outputs at lower sample rates for detection over a software controllable threshold.

3D packaging of a microfluidic system with sensory applications

NASA Astrophysics Data System (ADS)

Morrissey, Anthony; Kelly, Gerard; Alderman, John C.

1997-09-01

Among the main benefits of microsystem technology are its contributions to cost reductio, reliability and improved performance. however, the packaging of microsystems, and particularly microsensor, has proven to be one of the biggest limitations to their commercialization and the packaging of silicon sensor devices can be the most costly part of their fabrication. This paper describes the integration of 3D packaging of a microsystem. Central to the operation of the 3D demonstrator is a micromachined silicon membrane pump to supply fluids to a sensing chamber constructed about the active area of a sensor chip. This chip carries ISFET based chemical sensors, pressure sensors and thermal sensors. The electronics required for controlling and regulating the activity of the various sensors ar also available on this chip and as other chips in the 3D assembly. The demonstrator also contains a power supply module with optical fiber interconnections. All of these modules are integrated into a single plastic- encapsulated 3D vertical multichip module. The reliability of such a structure, initially proposed by Val was demonstrated by Barrett et al. An additional module available for inclusion in some of our assemblies is a test chip capable of measuring the packaging-induced stress experienced during and after assembly. The packaging process described produces a module with very high density and utilizes standard off-the-shelf components to minimize costs. As the sensor chip and micropump include micromachined silicon membranes and microvalves, the packaging of such structures has to allow consideration for the minimization of the packaging-induced stresses. With this in mind, low stress techniques, including the use of soft glob-top materials, were employed.

Clinicopathologic significance of minichromosome maintenance protein 2 and Tat-interacting protein 30 expression in benign and malignant lesions of the gallbladder.

PubMed

Liu, Dong-cai; Yang, Zhu-lin

2011-11-01

Gallbladder cancers are aggressive tumors with a poor prognosis and high mortality rate. To find specific biological markers for early diagnosis and prognosis and to develop possible alternative treatment strategies, we examined minichromosome maintenance protein 2 (MCM2) and Tat-interacting protein 30 (TIP30) expression in 108 gallbladder adenocarcinomas, 15 gallbladder polyps, 35 chronic cholecystitis tissues, and 46 peritumoral tissues using immunohistochemistry. Expression of MCM2 was significantly higher in adenocarcinomas than in peritumoral tissues (χ² = 8.41; P < .01), adenomatous polyps (χ² = 6.81; P < .01), and chronic cholecystitis (χ² = 21.00; P < .01). In contrast, Tat-interacting protein 30 expression was significantly less in adenocarcinomas than in peritumoral tissues (χ² = 13.26; P < .01), adenomatous polyps (χ² = 4.76; P < .05), and chronic cholecystitis (χ² = 18.93; P < .01). The benign lesions in gallbladder epithelium with positive MCM2 or negative Tat-interacting protein 30 expression showed moderate to severe atypical hyperplasia. Expression of MCM2 and absence of Tat-interacting protein 30 were significantly associated with poor differentiation, large tumor mass, lymph node metastasis, and invasion of adenocarcinoma. Univariate Kaplan-Meier analysis showed that either elevated MCM2 (P = .006) or lowered Tat-interacting protein 30 (P = .006) expression was closely associated with shorter overall survival. Multivariate Cox regression analysis revealed that expression of MCM2 (P = .007) or nonexpression of Tat-interacting protein 30 (P = .009) was an independent predictor of a poor prognosis in adenocarcinoma. Our results suggest that overexpression of MCM2 or loss of expression of Tat-interacting protein 30 is closely related to carcinogenesis, progression, biological behavior, and prognosis of gallbladder adenocarcinoma. Copyright © 2011 Elsevier Inc. All rights reserved.

Ki-67 and MCM-2 in Dental Follicle and Odontogenic Cysts: The Effects of Inflammation on Proliferative Markers

PubMed Central

Güler, Nurhan; Çomunoğlu, Nil; Cabbar, Fatih

2012-01-01

The aim of this study was to investigate whether there is any association between inflammation and the expression of markers of cell cycle entry (Ki-67 and MCM-2) in dental follicle (DF) of asymptomatic impacted teeth and odontogenic cysts. The study consisted of 70 DFs and 20 odontogenic cysts (radicular cyst (RC), dentigerous cyst (DC) and keratocytic odontogenic tumor (KCOT) located at posterior mandibular region. Histological findings of inflammation for all specimen and mucous cell prosoplasia, squamous metaplasia, glandular epithelium for all DFs were stained with hematoxyline and eosin, periodic acid schiff, alcian blue, and mucin. Epithelial cell proliferation was determined by using immunohistochemical labeling for Ki-67 and MCM-2. The histologic examinations showed 16% mucous cell prosoplasia, 54% squamous metaplasia, 20% glandular epithelium, 37% inflammation. Inflammation was detected in all RCs and %62 in DF, %43 in DC and KCOT. Positive correlation was found between the inflammation of DF and odontogenic cysts (P < 0.01). The mean Ki-67 and MCM-2 expressions were found 9, 64 ± 5, 99 and 6, 34 ± 3, 81 in DF, 11, 85 ± 9, 01 and 13, 6 ± 9, 94 in odontogenic cysts, respectively. While the mean Ki-67 expressions were statistically significant in DF and KCOT (P < 0.01), MCM-2 were significant in RC and KCOT (P < 0.01). MCM-2 expresion in RCs were statistically significant than KCOT (P < 0.01). The results of this study indicated that the higher MCM-2 expressions in RC than the KCOT might be related to the inflammation and this protein might be more sensitive to inflammation. PMID:22778705

Ki-67 and MCM-2 in dental follicle and odontogenic cysts: the effects of inflammation on proliferative markers.

PubMed

Güler, Nurhan; Comunoğlu, Nil; Cabbar, Fatih

2012-01-01

The aim of this study was to investigate whether there is any association between inflammation and the expression of markers of cell cycle entry (Ki-67 and MCM-2) in dental follicle (DF) of asymptomatic impacted teeth and odontogenic cysts. The study consisted of 70 DFs and 20 odontogenic cysts (radicular cyst (RC), dentigerous cyst (DC) and keratocytic odontogenic tumor (KCOT) located at posterior mandibular region. Histological findings of inflammation for all specimen and mucous cell prosoplasia, squamous metaplasia, glandular epithelium for all DFs were stained with hematoxyline and eosin, periodic acid schiff, alcian blue, and mucin. Epithelial cell proliferation was determined by using immunohistochemical labeling for Ki-67 and MCM-2. The histologic examinations showed 16% mucous cell prosoplasia, 54% squamous metaplasia, 20% glandular epithelium, 37% inflammation. Inflammation was detected in all RCs and %62 in DF, %43 in DC and KCOT. Positive correlation was found between the inflammation of DF and odontogenic cysts (P < 0.01). The mean Ki-67 and MCM-2 expressions were found 9, 64 ± 5, 99 and 6, 34 ± 3, 81 in DF, 11, 85 ± 9, 01 and 13, 6 ± 9, 94 in odontogenic cysts, respectively. While the mean Ki-67 expressions were statistically significant in DF and KCOT (P < 0.01), MCM-2 were significant in RC and KCOT (P < 0.01). MCM-2 expresion in RCs were statistically significant than KCOT (P < 0.01). The results of this study indicated that the higher MCM-2 expressions in RC than the KCOT might be related to the inflammation and this protein might be more sensitive to inflammation.

Characterization of Co and Fe-MCM-56 catalysts for NH3-SCR and N2O decomposition: An in situ FTIR study

NASA Astrophysics Data System (ADS)

Grzybek, Justyna; Gil, Barbara; Roth, Wieslaw J.; Skoczek, Monika; Kowalczyk, Andrzej; Chmielarz, Lucjan

2018-05-01

Two-step preparation of iron and cobalt-containing MCM-56 zeolites has been undertaken to evaluate the influence of their physicochemical properties in the selective catalytic reduction (NH3-SCR or DeNOx) of NO using NH3 as a reductant. Zeolites were prepared by the selective leaching of the framework cations by concentrated HNO3 solution and NH4F/HF mixture and consecutively, introduction of Co and Fe heteroatoms, in quantities below 1 wt%. Further calcination allowed to obtain highly dispersed active species. Their evaluation and speciation was realized by adsorption of pyridine and NO, followed by FTIR spectroscopy. Both Fe-MCM-56 zeolites showed excellent activities (maximum NO conversion 92%) with high selectivity to dinitrogen (above 99%) in the high temperature NH3-SCR process. High catalytic activity of Fe-MCM-56 zeolites was assigned to the formation of stable nitrates, delivering NO to react with NH3 at higher temperatures and suppressing the direct NO oxidation. It was found that more nitrates was formed in Fe-MCM-56 (HNO3) than in Fe-MCM-56 (HF/NH4F) and that could compensate for the lower Fe loading, resulting in very similar catalytic activity of both catalysts. At the same time both Co-and Fe-MCM-56 zeolites were moderately active in direct N2O decomposition, with maximum N2O conversion not higher than 80% and activity window starting at 500 °C. This phenomenon was expected since both types of catalysts contained well dispersed active centers, not beneficial for this reaction.

New MCM8 mutation associated with premature ovarian insufficiency and chromosomal instability in a highly consanguineous Tunisian family.

PubMed

Bouali, Nouha; Francou, Bruno; Bouligand, Jérôme; Imanci, Dilek; Dimassi, Sarra; Tosca, Lucie; Zaouali, Monia; Mougou, Soumaya; Young, Jacques; Saad, Ali; Guiochon-Mantel, Anne

2017-10-01

To identify the gene(s) involved in the etiology of premature ovarian insufficiency in a highly consanguineous Tunisian family. Genetic analysis of a large consanguineous family with several affected siblings. University hospital-based cytogenetics and molecular genetics laboratories. A highly consanguineous Tunisian family with several affected siblings born to healthy second-degree cousins. None. Targeted exome sequencing was performed by next-generation sequencing for affected family members. Mutations were validated by Sanger sequencing. Functional experiments were performed to explore the deleterious effects of the identified mutation. DNA damage was induced by increasing mitomycin C (MMC) concentrations on cultured peripheral lymphocytes. Analysis of the next-generation sequencing data revealed a new homozygous missense mutation in the minichromosome maintenance 8 gene (MCM8).This homozygous mutation (c. 482A>C; p.His161Pro) was predicted to be deleterious and segregated with the disease in the family. MCM8 participates in homologous recombination during meiosis and DNA double-stranded break repair by dimerizing with MCM9. Mcm8 knock out results in an early block in follicle development and small gonads. Given this, we tested the chromosomal breakage repair capacity of homozygous and heterozygous MCM8 p.His161Pro mutation on cultured peripheral lymphocytes exposed to increasing MMC concentrations. We found that chromosomal breakage after MMC exposure was significantly higher in cells from homozygously affected individuals than in those from a healthy control. Our findings provide additional support to the view that MCM8 mutations are involved in the primary ovarian insufficiency phenotype. Copyright © 2017 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Switch I-dependent allosteric signaling in a G-protein chaperone-B12 enzyme complex.

PubMed

Campanello, Gregory C; Lofgren, Michael; Yokom, Adam L; Southworth, Daniel R; Banerjee, Ruma

2017-10-27

G-proteins regulate various processes ranging from DNA replication and protein synthesis to cytoskeletal dynamics and cofactor assimilation and serve as models for uncovering strategies deployed for allosteric signal transduction. MeaB is a multifunctional G-protein chaperone, which gates loading of the active 5'-deoxyadenosylcobalamin cofactor onto methylmalonyl-CoA mutase (MCM) and precludes loading of inactive cofactor forms. MeaB also safeguards MCM, which uses radical chemistry, against inactivation and rescues MCM inactivated during catalytic turnover by using the GTP-binding energy to offload inactive cofactor. The conserved switch I and II signaling motifs used by G-proteins are predicted to mediate allosteric regulation in response to nucleotide binding and hydrolysis in MeaB. Herein, we targeted conserved residues in the MeaB switch I motif to interrogate the function of this loop. Unexpectedly, the switch I mutations had only modest effects on GTP binding and on GTPase activity and did not perturb stability of the MCM-MeaB complex. However, these mutations disrupted multiple MeaB chaperone functions, including cofactor editing, loading, and offloading. Hence, although residues in the switch I motif are not essential for catalysis, they are important for allosteric regulation. Furthermore, single-particle EM analysis revealed, for the first time, the overall architecture of the MCM-MeaB complex, which exhibits a 2:1 stoichiometry. These EM studies also demonstrate that the complex exhibits considerable conformational flexibility. In conclusion, the switch I element does not significantly stabilize the MCM-MeaB complex or influence the affinity of MeaB for GTP but is required for transducing signals between MeaB and MCM. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Bimetallic iron and cobalt incorporated MFI/MCM-41 composite and its catalytic properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Baoshan, E-mail: bsli@mail.buct.edu.cn; Xu, Junqing; Li, Xiao

2012-05-15

Graphical abstract: The formation of FeCo-MFI/MCM-41 composite is based on two steps, the first step of synthesizing the MFI-type proto-zeolite unites under hydrothermal conditions. The second step of assembling these zeolite fragment together new silica and heteroatom source on the CTAB surfactant micelle to synthesize the mesoporous product with hexagonal structure. Highlights: Black-Right-Pointing-Pointer Bimetallic iron and cobalt incorporated MFI/MCM-41 composite was prepared using templating method. Black-Right-Pointing-Pointer FeCo-MFI/MCM-41 composite simultaneously possessed two kinds of meso- and micro-porous structures. Black-Right-Pointing-Pointer Iron and cobalt ions incorporated into the silica framework with tetrahedral coordination. -- Abstract: The MFI/MCM-41 composite material with bimetallic Fe andmore » Co incorporation was prepared using templating method via a two-step hydrothermal crystallization procedure. The obtained products were characterized by a series of techniques including powder X-ray diffraction, N{sub 2} sorption, transmission electron microscopy, scanning electron microscope, H{sub 2} temperature programmed reduction, thermal analyses, and X-ray absorption fine structure spectroscopy of the Fe and Co K-edge. The catalytic properties of the products were investigated by residual oil hydrocracking reactions. Characterization results showed that the FeCo-MFI/MCM-41 composite simultaneously possessed two kinds of stable meso- and micro-porous structures. Iron and cobalt ions were incorporated into the silicon framework, which was confirmed by H{sub 2} temperature programmed reduction and X-ray absorption fine structure spectroscopy. This composite presented excellent activities in hydrocracking of residual oil, which was superior to the pure materials of silicate-1/MCM-41.« less

Recycling of surfactant template in mesoporous MCM-41 synthesis

NASA Astrophysics Data System (ADS)

Lai, J. Y.; Twaiq, F.; Ngu, L. H.

2017-06-01

The recycling of surfactant template is investigated through the reuse of the surfactant template in the mesoporous MCM-41 synthesis process. In the synthesis of MCM-41, tetraethylorthosilicate (TEOS) solution in water was utilized as the silica source while hexadecyltrimethylammonium bromide (CTAB) solution in ethyl alcohol was used as a surfactant template. The synthesized gel is formed thoroughly by mixing the two solutions under acid conditions with a pH value of 0.5 for 1 hour and kept for crystallization for 48 hours. The as-synthesized MCM-41 powder is recovered by filtration while the filtrate (mother liquor) was then reused for the second synthesis cycle. The synthesis procedure was repeated till no further solid product was formed. The synthesized gel was not produced in the unifying solution in the fifth cycle of MCM-41 synthesis. The quality of the calcined MCM-41 powder produced in each synthesis cycle was evaluated by calculating the amount of MCM-41 produced and the surface area of the powder product. The result showed that 1.28, 0.37, 1.64, 1.90 and 0.037 g were obtained in the 1st, 2nd, 3rd, 4th and 5th synthesis cycle, respectively. The surface area of the powder produced was found to be 1170, 916, 728, and 508 m2/g for 1st, 2nd, 3rd and 4th respectively. The concentration of the surfactant template has reached value lower than the critical micelle concentration (CMC) and remained constant after the 4th cycle. There was no further formation of gel due to low availability in the interaction between silicate anions and surfactant cations when the amount of TEOS was fixed for every synthesis cycle.

Characterization of Co and Fe-MCM-56 catalysts for NH3-SCR and N2O decomposition: An in situ FTIR study.

PubMed

Grzybek, Justyna; Gil, Barbara; Roth, Wieslaw J; Skoczek, Monika; Kowalczyk, Andrzej; Chmielarz, Lucjan

2018-05-05

Two-step preparation of iron and cobalt-containing MCM-56 zeolites has been undertaken to evaluate the influence of their physicochemical properties in the selective catalytic reduction (NH 3 -SCR or DeNOx) of NO using NH 3 as a reductant. Zeolites were prepared by the selective leaching of the framework cations by concentrated HNO 3 solution and NH 4 F/HF mixture and consecutively, introduction of Co and Fe heteroatoms, in quantities below 1wt%. Further calcination allowed to obtain highly dispersed active species. Their evaluation and speciation was realized by adsorption of pyridine and NO, followed by FTIR spectroscopy. Both Fe-MCM-56 zeolites showed excellent activities (maximum NO conversion 92%) with high selectivity to dinitrogen (above 99%) in the high temperature NH 3 -SCR process. High catalytic activity of Fe-MCM-56 zeolites was assigned to the formation of stable nitrates, delivering NO to react with NH 3 at higher temperatures and suppressing the direct NO oxidation. It was found that more nitrates was formed in Fe-MCM-56 (HNO 3 ) than in Fe-MCM-56 (HF/NH 4 F) and that could compensate for the lower Fe loading, resulting in very similar catalytic activity of both catalysts. At the same time both Co-and Fe-MCM-56 zeolites were moderately active in direct N 2 O decomposition, with maximum N 2 O conversion not higher than 80% and activity window starting at 500°C. This phenomenon was expected since both types of catalysts contained well dispersed active centers, not beneficial for this reaction. Copyright © 2018 Elsevier B.V. All rights reserved.

Ibuprofen in mesopores of Mobil Crystalline Material 41 (MCM-41): a deeper understanding.

PubMed

Skorupska, Ewa; Jeziorna, Agata; Paluch, Piotr; Potrzebowski, Marek J

2014-05-05

In this work, we compared two methods (incipient wetness and melting) for the encapsulation of ibuprofen in the pores of Mobil Crystalline Material 41 (MCM-41) through NMR (nuclear magnetic resonance) spectroscopy. (1)H NMR spectra were recorded under very fast MAS (sample spinning 60 kHz) conditions in both 1D and 2D mode (NOESY sequence). We also performed (13)C cross-polarization magic angle spinning (CP/MAS) experiments, (13)C single pulse experiments (SPE), and (1)H-(13)C HSQC HR/MAS (heteronuclear single quantum coherence high resolution) HR/MAS correlations. Evaluation of the encapsulation methods included an analysis of the filling factor of the drug into the pores. The stability of Ibu/MCM in an environment of ethanol or water vapor was tested. Our study showed that melting a mixture of Ibu and MCM is a much more efficient method of confining the drug in the pores compared to incipient wetness. The optimal experiments for the former method achieved a filling factor of approximately 60%. We concluded that the major limitation to the applicability of the incipient wetness method (filling factor ca. 20%) is the high affinity of solvent (typically ethanol) for MCM-41. We found that even ethanol vapor can remove Ibu from the pores. When a sample of Ibu/MCM was stored for a few hours in a closed vessel with ethanol vapor, Ibu was transported from the pores to the outer walls of MCM. We observed a similar phenomenon with water vapor, although this process is slower compared to the analogous procedure using ethanol. Our study clearly demonstrates that existing methods used to encapsulate drugs in mesoporous silica nanoparticles (MSNs) require reevaluation.

Preparation and controlled release of mesoporous MCM-41/propranolol hydrochloride composite drug.

PubMed

Zhai, Qing-Zhou

2013-01-01

This article used MCM-41 as a carrier for the assembly of propranolol hydrochloride by the impregnation method. By means of chemical analysis, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy and low-temperature N(2) adsorption-desorption at 77 K, the characterization was made for the prepared materials. The propranolol hydrochloride guest assembly capacity was 316.20 ± 0.31 mg/g (drug/MCM-41). Powder XRD test results indicated that during the process of incorporation, the frameworks of the MCM-41 were not destroyed and the crystalline degrees of the host-guest nanocomposite materials prepared still remained highly ordered. Characterization by SEM and TEM showed that the composite material presented spherical particle and the average particle size of composite material was 186 nm. FT-IR spectra showed that the MCM-41 framework existed well in the (MCM-41)-propranolol hydrochloride composite. Low-temperature nitrogen adsorption-desorption results at 77 K showed that the guest partially occupied the channels of the molecular sieves. Results of the release of the prepared composite drug in simulated body fluid indicated that the drug can release up to 32 h and its maximum released amount was 99.20 ± 0.11%. In the simulated gastric juice release pattern of drug, the maximum time for the drug release was discovered to be 6 h and the maximum cumulative released amount of propranolol hydrochloride was 45.13 ± 0.23%. The drug sustained-release time was 10 h in simulated intestinal fluid and the maximum cumulative released amount was 62.05 ± 0.13%. The prepared MCM-41 is a well-controlled drug delivery carrier.

An empirical description of the dispersion of 5th and 95th percentiles in worldwide anthropometric data applied to estimating accommodation with unknown correlation values.

PubMed

Albin, Thomas J; Vink, Peter

2015-01-01

Anthropometric data are assumed to have a Gaussian (Normal) distribution, but if non-Gaussian, accommodation estimates are affected. When data are limited, users may choose to combine anthropometric elements by Combining Percentiles (CP) (adding or subtracting), despite known adverse effects. This study examined whether global anthropometric data are Gaussian distributed. It compared the Median Correlation Method (MCM) of combining anthropometric elements with unknown correlations to CP to determine if MCM provides better estimates of percentile values and accommodation. Percentile values of 604 male and female anthropometric data drawn from seven countries worldwide were expressed as standard scores. The standard scores were tested to determine if they were consistent with a Gaussian distribution. Empirical multipliers for determining percentile values were developed.In a test case, five anthropometric elements descriptive of seating were combined in addition and subtraction models. Percentile values were estimated for each model by CP, MCM with Gaussian distributed data, or MCM with empirically distributed data. The 5th and 95th percentile values of a dataset of global anthropometric data are shown to be asymmetrically distributed. MCM with empirical multipliers gave more accurate estimates of 5th and 95th percentiles values. Anthropometric data are not Gaussian distributed. The MCM method is more accurate than adding or subtracting percentiles.

Recovery of silica from electronic waste for the synthesis of cubic MCM-48 and its application in preparing ordered mesoporous carbon molecular sieves using a green approach

NASA Astrophysics Data System (ADS)

Liou, Tzong-Horng

2012-07-01

The electronics industry is one of the world's fastest growing manufacturing industries. However, e-waste has become a serious pollution problem. This study reports the recovery of e-waste for preparing valuable MCM-48 and ordered mesoporous carbon for the first time. Specifically, this study adopts an alkali-extracted method to obtain sodium silicate precursors from electronic packaging resin ash. The influence of synthesis variables such as gelation pH, neutral/cationic surfactant ratio, hydrothermal treatment temperature, and calcination temperature on the mesophase of MCM-48 materials is investigated. Experimental results confirm that well-ordered cubic MCM-48 materials were synthesized in strongly acidic and strongly basic media. The resulting mesoporous silica had a high surface area of 1,317 m2/g, mean pore size of about 3.0 nm, and a high purity of 99.87 wt%. Ordered mesoporous carbon with high surface area (1,715 m2/g) and uniform pore size of CMK-1 type was successfully prepared by impregnating MCM-48 template using the resin waste. The carbon structure was sensitive to the sulfuric acid concentration and carbonization temperature. Converting e-waste into MCM-48 materials not only eliminates the disposal problem of e-waste, but also transforms industrial waste into a useful nanomaterial.

A STE12 homologue of the homothallic ascomycete Sordaria macrospora interacts with the MADS box protein MCM1 and is required for ascosporogenesis.

PubMed

Nolting, Nicole; Pöggeler, Stefanie

2006-11-01

The MADS box protein MCM1 controls diverse developmental processes and is essential for fruiting body formation in the homothallic ascomycete Sordaria macrospora. MADS box proteins derive their regulatory specificity from a wide range of different protein interactions. We have recently shown that the S. macrospora MCM1 is able to interact with the alpha-domain mating-type protein SMTA-1. To further evaluate the functional roles of MCM1, we used the yeast two-hybrid approach to identify MCM1-interacting proteins. From this screen, we isolated a protein with a putative N-terminal homeodomain and C-terminal C2/H2-Zn2+ finger domains. The protein is a member of the highly conserved fungal STE12 transcription factor family of proteins and was therefore termed STE12. Furthermore, we demonstrate by means of two-hybrid and far western analysis that in addition to MCM1, the S. macrospora STE12 protein is able to interact with the mating-type protein SMTA-1. Unlike the situation in the closely related heterothallic ascomycete Neurospora crassa, deletion (Delta) of the ste12 gene in S. macrospora neither affects vegetative growth nor fruiting body formation. However, ascus and ascospore development are highly impaired by the Deltaste12 mutation. Our data provide another example of the functional divergence within the fungal STE12 transcription factor family.

Butanol Dehydration over V₂O₅-TiO₂/MCM-41 Catalysts Prepared via Liquid Phase Atomic Layer Deposition.

PubMed

Choi, Hyeonhee; Bae, Jung-Hyun; Kim, Do Heui; Park, Young-Kwon; Jeon, Jong-Ki

2013-04-29

MCM-41 was used as a support and, by using atomic layer deposition (ALD) in the liquid phase, a catalyst was prepared by consecutively loading titanium oxide and vanadium oxide to the support. This research analyzes the effect of the loading amount of vanadium oxide on the acidic characteristics and catalytic performance in the dehydration of butanol. The physical and chemical characteristics of the TiO₂-V₂O₅/MCM-41 catalysts were analyzed using XRF, BET, NH₃-TPD, XRD, Py-IR, and XPS. The dehydration reaction of butanol was performed in a fixed bed reactor. For the samples with vanadium oxide loaded to TiO₂/MCM-41 sample using the liquid phase ALD method, it was possible to increase the loading amount until the amount of vanadium oxide reached 12.1 wt %. It was confirmed that the structural properties of the mesoporous silica were retained well after titanium oxide and vanadium loading. The NH₃-TPD and Py-IR results indicated that weak acid sites were produced over the TiO₂/MCM-41 samples, which is attributed to the generation of Lewis acid sites. The highest activity of the V₂O₅(12.1)-TiO₂/MCM-41 catalyst in 2-butanol dehydration is ascribed to it having the highest number of Lewis acid sites, as well as the highest vanadium dispersion.

[Degradation of m-Cresol with Fe-MCM-41 in Catalytic Ozonation].

PubMed

Sun, Wen-jing; Wang, Ya-min; Wei, Huang-zhao; Wang, Sen; Li, Xu-ning; Li, Jing-mei; Sun, Cheng-lin; An, Lu-yang

2015-04-01

Fe-MCM-41 was first used for the treatment of m-cresol in catalytic ozonation. The effect of the percentage of Fe dopping mass, catalyst dosage and the natural concentration of substrate on m-cresol conversion and TOC removal were studied. The structural property of Fe-MCM-41 was characterized by X-ray diffraction, temperature-programmed reduction, Mössbauer spectra and BET of catalysts. The results showed that Fe dopping mass had a great effect on the catalytic activity of Fe-MCM-41 in catalytic ozonation and the optimal percentage of dopping mass was 4.4% (wt). The results showed that with Fe dopping mass increase, the degree of crystallinity became weaker, the crystal surface distance reduced, as well as the specific surface area, pore volume and aperture. γ-Fe2O3 was the only form staying on the surface of MCM-41, and the catalyst had good ferromagnetism and stability. Ozonation played a role of both direct oxidation and indirect oxidation in the reaction, approximately the same ratio. Under the experimental condition of the natural pH of model wastewater,using 4.4% (wt) Fe-MCM-41 as catalyst, natural concentration of m-cresol 500 mg x L(-1), catalyst dosage 0.1 g x L(-1) and reaction time 30 min, m-cresol conversion and TOC removal were 100% and 26.8%, respectively.

Eco-friendly synthesis for MCM-41 nanoporous materials using the non-reacted reagents in mother liquor.

PubMed

Ng, Eng-Poh; Goh, Jia-Yi; Ling, Tau Chuan; Mukti, Rino R

2013-03-04

Nanoporous materials such as Mobil composite material number 41 (MCM-41) are attractive for applications such as catalysis, adsorption, supports, and carriers. Green synthesis of MCM-41 is particularly appealing because the chemical reagents are useful and valuable. We report on the eco-friendly synthesis of MCM-41 nanoporous materials via multi-cycle approach by re-using the non-reacted reagents in supernatant as mother liquor after separating the solid product. This approach was achieved via minimal requirement of chemical compensation where additional fresh reactants were added into the mother liquor followed by pH adjustment after each cycle of synthesis. The solid product of each successive batch was collected and characterized while the non-reacted reagents in supernatant can be recovered and re-used to produce subsequent cycle of MCM-41. The multi-cycle synthesis is demonstrated up to three times in this research. This approach suggests a low cost and eco-friendly synthesis of nanoporous material since less waste is discarded after the product has been collected, and in addition, product yield can be maintained at the high level.

Eco-friendly synthesis for MCM-41 nanoporous materials using the non-reacted reagents in mother liquor

PubMed Central

2013-01-01

Nanoporous materials such as Mobil composite material number 41 (MCM-41) are attractive for applications such as catalysis, adsorption, supports, and carriers. Green synthesis of MCM-41 is particularly appealing because the chemical reagents are useful and valuable. We report on the eco-friendly synthesis of MCM-41 nanoporous materials via multi-cycle approach by re-using the non-reacted reagents in supernatant as mother liquor after separating the solid product. This approach was achieved via minimal requirement of chemical compensation where additional fresh reactants were added into the mother liquor followed by pH adjustment after each cycle of synthesis. The solid product of each successive batch was collected and characterized while the non-reacted reagents in supernatant can be recovered and re-used to produce subsequent cycle of MCM-41. The multi-cycle synthesis is demonstrated up to three times in this research. This approach suggests a low cost and eco-friendly synthesis of nanoporous material since less waste is discarded after the product has been collected, and in addition, product yield can be maintained at the high level. PMID:23497184

CuO nanoparticles encapsulated inside Al-MCM-41 mesoporous materials via direct synthetic route

PubMed Central

Huo, Chengli; Ouyang, Jing; Yang, Huaming

2014-01-01

Highly ordered aluminum-containing mesoporous silica (Al-MCM-41) was prepared using attapulgite clay mineral as a Si and Al source. Mesoporous complexes embedded with CuO nanoparticles were subsequently prepared using various copper sources and different copper loadings in a direct synthetic route. The resulting CuO/Al-MCM-41 composite possessed p6mm hexagonally symmetry, well-developed mesoporosity, and relatively high BET surface area. In comparison to pure silica, these mesoporous materials embedded with CuO nanoparticles exhibited smaller pore diameter, thicker pore wall, and enhanced thermal stability. Long-range order in the aforementioned samples was observed for copper weight percentages as high as 30%. Furthermore, a significant blue shift of the absorption edge for the samples was observed when compared with that of bulk CuO. H2-TPR measurements showed that the direct-synthesized CuO/Al-MCM-41 exhibited remarkable redox properties compared to the post-synthesized samples, and most of the CuO nanoparticles were encapsulated within the mesoporous structures. The possible interaction between CuO and Al-MCM-41 was also investigated. PMID:24419589

Eco-friendly synthesis for MCM-41 nanoporous materials using the non-reacted reagents in mother liquor

NASA Astrophysics Data System (ADS)

Ng, Eng-Poh; Goh, Jia-Yi; Ling, Tau Chuan; Mukti, Rino R.

2013-03-01

Nanoporous materials such as Mobil composite material number 41 (MCM-41) are attractive for applications such as catalysis, adsorption, supports, and carriers. Green synthesis of MCM-41 is particularly appealing because the chemical reagents are useful and valuable. We report on the eco-friendly synthesis of MCM-41 nanoporous materials via multi-cycle approach by re-using the non-reacted reagents in supernatant as mother liquor after separating the solid product. This approach was achieved via minimal requirement of chemical compensation where additional fresh reactants were added into the mother liquor followed by pH adjustment after each cycle of synthesis. The solid product of each successive batch was collected and characterized while the non-reacted reagents in supernatant can be recovered and re-used to produce subsequent cycle of MCM-41. The multi-cycle synthesis is demonstrated up to three times in this research. This approach suggests a low cost and eco-friendly synthesis of nanoporous material since less waste is discarded after the product has been collected, and in addition, product yield can be maintained at the high level.

Multifunctional materials such as MCM-41÷Fe3O4÷folic acid as drug delivery system.

PubMed

Popescu, Simona; Ardelean, Ioana Lavinia; Gudovan, Dragoş; Rădulescu, Marius; Ficai, Denisa; Ficai, Anton; Vasile, Bogdan Ştefan; Andronescu, Ecaterina

2016-01-01

In this study, MCM-41 mesoporous silica nanoparticles (NPs) and MCM-41÷Fe3O4 mesoporous silica NPs were prepared by sol-gel method using CTAB (cetyltrimethylammonium bromide) as template and TEOS (tetraethyl orthosilicate) as silica precursor in order to use these materials as drug delivery system (DDS) for different biologically active agents. The MCM-41 and MCM-41÷Fe3O4 mesoporous silica NPs were characterized using specific physico-chemical methods [transmission electron microscopy (TEM), scanning electron microscopy (SEM), nitrogen adsorption and desorption studies - BET (Brunauer-Emmett-Teller) method, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy], while the release studies were done by a high-performance liquid chromatography (HPLC)-modified method. The pH dependence of the delivery of folic acid from the mesoporous structures was analyzed and found that the release is pH sensitive. The lower delivery at strongly acid pH comparing with neutral/slightly alkaline pH could be beneficial because in stomach the folic acid can be destroyed.

Hexamethyldisilazane Removal with Mesoporous Materials Prepared from Calcium Fluoride Sludge.

PubMed

Kao, Ching-Yang; Lin, Min-Fa; Nguyen, Nhat-Thien; Tsai, Hsiao-Hsin; Chang, Luh-Maan; Chen, Po-Han; Chang, Chang-Tang

2018-05-01

A large amount of calcium fluoride sludge is generated by the semiconductor industry every year. It also requires a high amount of fuel consumption using rotor concentrators and thermal oxidizers to treat VOCs. The mesoporous adsorbent prepared by calcium fluoride sludge was used for VOCs treatment. The semiconductor industry employs HMDS to promote the adhesion of photo-resistant material to oxide(s) due to the formation of silicon dioxide, which blocks porous adsorbents. The adsorption of HMDS (Hexamethyldisiloxane) was tested with mesoporous silica materials synthesized from calcium fluoride (CF-MCM). The resulting samples were characterized by XRD, XRF, FTIR, N2-adsorption-desorption techniques. The prepared samples possessed high specific surface area, large pore volume and large pore diameter. The crystal patterns of CF-MCM were similar with Mobil composite matter (MCM-41) from TEM image. The adsorption capacity of HMDS with CF-MCM was 40 and 80 mg g-1, respectively, under 100 and 500 ppm HMDS. The effects of operation parameters, such as contact time and mixture concentration, on the performance of CF-MCM were also discussed in this study.

Structure of the eukaryotic replicative CMG helicase suggests a pumpjack motion for translocation

DOE PAGES

Yuan, Zuanning; Bai, Lin; Sun, Jingchuan; ...

2016-02-08

The CMG helicase is composed of Cdc45, Mcm2–7 and GINS. Here we report the structure of the Saccharomyces cerevisiae CMG, determined by cryo-EM at a resolution of 3.7–4.8 Å. The structure reveals that GINS and Cdc45 scaffold the N tier of the helicase while enabling motion of the AAA+ C tier. CMG exists in two alternating conformations, compact and extended, thus suggesting that the helicase moves like an inchworm. The N-terminal regions of Mcm2–7, braced by Cdc45–GINS, form a rigid platform upon which the AAA+ C domains make longitudinal motions, nodding up and down like an oil-rig pumpjack attached tomore » a stable platform. The Mcm ring is remodeled in CMG relative to the inactive Mcm2–7 double hexamer. In addition, the Mcm5 winged-helix domain is inserted into the central channel, thus blocking entry of double-stranded DNA and supporting a steric-exclusion DNA-unwinding model.« less

Study on the pyrolysis of cellulose for bio-oil with mesoporous molecular sieve catalysts.

PubMed

Yu, Feng-wen; Ji, Deng-xiang; Nie, Yong; Luo, Yao; Huang, Cheng-jie; Ji, Jian-bing

2012-09-01

Mesoporous materials possess a hexagonal array of uniform mesopores, high surface areas, and moderate acidity. They are one of the important catalysts in the field of catalytic pyrolysis. In this paper, mesoporous materials of Al-MCM-41, La-Al-MCM-41, and Ce-Al-MCM-41 were synthesized, characterized, and tested as catalysts in the cellulose catalytic pyrolysis process using a fixed bed pyrolysis reactor. The results showed that mesoporous materials exhibited a strong influence on the pyrolytic behavior of cellulose. The presence of these mesoporous molecular sieve catalysts could vary the yield of products, which was that they could decrease the yield of liquid and char and increase the yield of gas product, and could promote high-carbon chain compounds to break into low-carbon chain compounds. Mesoporous molecular sieve catalysts were benefit to the reaction of dehydrogenation and deoxidation and the breakdown of carbon chain. Further, La-Al-MCM-41 and Ce-Al-MCM-41 catalysts can produce more toluene and 2-methoxy-phenol, as compared to the non-catalytic runs.

The Neptune/Triton Explorer Mission: A Concept Feasibility Study

NASA Technical Reports Server (NTRS)

Esper, Jaime

2003-01-01

Technological advances over the next 10 to 15 years promise to enable a number of smaller, more capable science missions to the outer planets. With the inception of miniaturized spacecraft for a wide range of applications, both in large clusters around Earth, and for deep space missions, NASA is currently in the process of redefining the way science is being gathered. Technologies such as 3-Dimensional Multi-Chip Modules, Micro-machined Electromechanical Devices, Multi Functional Structures, miniaturized transponders, miniaturized propulsion systems, variable emissivity thermal coatings, and artificial intelligence systems are currently in research and development, and are scheduled to fly (or have flown) in a number of missions. This study will leverage on these and other technologies in the design of a lightweight Neptune orbiter unlike any other that has been proposed to date. The Neptune/Triton Explorer (NExTEP) spacecraft uses solar electric earth gravity assist and aero capture maneuvers to achieve its intended target orbit. Either a Taurus or Delta-class launch vehicle may be used to accomplish the mission.

Optical interconnection using polyimide waveguide for multichip module

NASA Astrophysics Data System (ADS)

Koyanagi, Mitsumasa

1996-01-01

We have developed a parallel processor system with 152 RISC processor chips specific for Monte-Carlo analysis. This system has the ring-bus architecture. The performance of several Gflops is expected in this system according to the computer simulation. However, it was revealed that the data transfer speed of the bus has to be increased more dramatically in order to further increase the performance. Then, we propose to introduce the optical interconnection into the parallel processor system to increase the data transfer speed of the buses. The double ringbus architecture is employed in this new parallel processor system with optical interconnection. The free-space optical interconnection arid the optical waveguide are used for the optical ring-bus. Thin polyimide film was used to form the optical waveguide. A relatively low propagation loss was achieved in the polyimide optical waveguide. In addition, it was confirmed that the propagation direction of signal light can be easily changed by using a micro-mirror.

Optical interconnection using polyimide waveguide for multichip module

NASA Astrophysics Data System (ADS)

Koyanagi, Mitsumasa

1996-01-01

We have developed a parallel processor system with 152 RISC processor chips specific for Monte-Carlo analysis. This system has the ring-bus architecture. The performance of several Gflops is expected in this system according to the computer simulation. However, it was revealed that the data transfer speed of the bus has to be increased more dramatically in order to further increase the performance. Then, we propose to introduce the optical interconnection into the parallel processor system to increase the data transfer speed of the buses. The double ring-bus architecture is employed in this new parallel processor system with optical interconnection. The free-space optical interconnection and the optical waveguide are used for the optical ring-bus. Thin polyimide film was used to form the optical waveguide. A relatively low propagation loss was achieved in the polyimide optical waveguide. In addition, it was confirmed that the propagation direction of signal light can be easily changed by using a micro-mirror.

Tunable All-Solid-State Local Oscillators to 1900 GHz

NASA Technical Reports Server (NTRS)

Ward, John; Chattopadhyay, Goutam; Maestrini, Alain; Schlecht, Erich; Gill, John; Javadi, Hamid; Pukala, David; Maiwald, Frank; Mehdi, Imran

2004-01-01

We present a status report of an ongoing effort to develop robust tunable all-solid-state sources up to 1900 GHz for the Heterodyne Instrument for the Far Infrared (HIFI) on the Herschel Space Observatory. GaAs based multi-chip power amplifier modules at W-band are used to drive cascaded chains of multipliers. We have demonstrated performance from chains comprised of four doublers up to 1600 GHz as well as from a x2x3x3 chain to 1900 GHz. Measured peak output power of 23 (micro)W at 1782 GHz and 2.6 (micro)W at 1900 GHz has been achieved when the multipliers are cooled to 120K. The 1900 GHz tripler was pumped with a four anode tripler that produces a peak of 4 mW at 630 GHz when cooled to 120 K. We believe that these sources can now be used to pump hot electron bolometer (HEB) heterodyne mixers.ter (HEB) heterodyne mixers.

Ion implantation enhanced metal-Si-metal photodetectors

NASA Astrophysics Data System (ADS)

Sharma, A. K.; Scott, K. A. M.; Brueck, S. R. J.; Zolper, J. C.; Myers, D. R.

1994-05-01

The quantum efficiency and frequency response of simple Ni-Si-Ni metal-semiconductor-metal (MSM) photodetectors at long wavelengths are significantly enhanced with a simple, ion-implantation step to create a highly absorbing region approx. 1 micron below the Si surface. The internal quantum efficiency is improved by a factor of approx. 3 at 860 nm (to 64%) and a full factor of ten at 1.06 microns (to 23%) as compared with otherwise identical unimplanted devices. Dark currents are only slightly affected by the implantation process and are as low as 630 pA for a 4.5-micron gap device at 10-V bias. Dramatic improvement in the impulse response is observed, 100 ps vs. 600 ps, also at 10-V bias and 4.5-micron gap, due to the elimination of carrier diffusion tails in the implanted devices. Due to its planar structure, this device is fully VLSI compatible. Potential applications include optical interconnections for local area networks and multi-chip modules.

Microchannel cooling of face down bonded chips

DOEpatents

Bernhardt, Anthony F.

1993-01-01

Microchannel cooling is applied to flip-chip bonded integrated circuits, in a manner which maintains the advantages of flip-chip bonds, while overcoming the difficulties encountered in cooling the chips. The technique is suited to either multichip integrated circuit boards in a plane, or to stacks of circuit boards in a three dimensional interconnect structure. Integrated circuit chips are mounted on a circuit board using flip-chip or control collapse bonds. A microchannel structure is essentially permanently coupled with the back of the chip. A coolant delivery manifold delivers coolant to the microchannel structure, and a seal consisting of a compressible elastomer is provided between the coolant delivery manifold and the microchannel structure. The integrated circuit chip and microchannel structure are connected together to form a replaceable integrated circuit module which can be easily decoupled from the coolant delivery manifold and the circuit board. The coolant supply manifolds may be disposed between the circuit boards in a stack and coupled to supplies of coolant through a side of the stack.

Possibilities for mixed mode chip manufacturing in EUROPRACTICE

NASA Astrophysics Data System (ADS)

Das, C.

1997-02-01

EUROPRACTICE is an EC initiative under the ESPRIT programme which aims to stimulate the wider exploitation of state-of-the-art microelectronics technologies by European industry and to enhance European industrial competitiveness in the global market-place. Through EUROPRACTICE, the EC has created a range of Basic Services that offer users a cost-effective and flexible means of accessing three main microelectronics-based technologies: Application Specific Integrated Circuit (ASICs), Multi-Chip Modules (MCMs) and Microsystems. EUROPRACTICE Basic Services reduce the cost and risk for companies wishing to begin using these technologies. EUROPRACTICE offers a fully supported, low cost route for companies to design and fabricate ASICs for their individual applications. Low cost is achieved by consolidating designs from many users onto a single semiconductor wafer (MPW: Multi Project Wafer). The EUROPRACTICE IC Manufacturing Service (ICMS) offers a broad range of fabrication technologies including CMOS, BiCMOS and GaAs. The Service extends from enabling users to produce prototype ASICs for testing and evaluation, through to low-volume production runs.

CLCA1 and TMEM16A: the link towards a potential cure for airway diseases.

PubMed

Brett, Tom J

2015-10-01

The hallmark traits of chronic obstructive airway diseases are inflammation, airway constriction due to hyperreactivity and mucus overproduction. The current common treatments for asthma and chronic obstructive pulmonary disease target the first two traits with none currently targeting mucus overproduction. The main source of obstructive mucus production is mucus cell metaplasia (MCM), the transdifferentiation of airway epithelial cells into mucus-producing goblet cells, in the small airways. Our current understanding of MCM is profusely incomplete. Few of the molecular players involved in driving MCM in humans have been identified and for many of those that have, their functions and mechanisms are unknown. This fact has limited the development of therapeutics that target mucus overproduction by inhibiting MCM. Current work in the field is aiming to change that.

In situ 3D nanoprinting of free-form coupling elements for hybrid photonic integration

NASA Astrophysics Data System (ADS)

Dietrich, P.-I.; Blaicher, M.; Reuter, I.; Billah, M.; Hoose, T.; Hofmann, A.; Caer, C.; Dangel, R.; Offrein, B.; Troppenz, U.; Moehrle, M.; Freude, W.; Koos, C.

2018-04-01

Hybrid photonic integration combines complementary advantages of different material platforms, offering superior performance and flexibility compared with monolithic approaches. This applies in particular to multi-chip concepts, where components can be individually optimized and tested. The assembly of such systems, however, requires expensive high-precision alignment and adaptation of optical mode profiles. We show that these challenges can be overcome by in situ printing of facet-attached beam-shaping elements. Our approach allows precise adaptation of vastly dissimilar mode profiles and permits alignment tolerances compatible with cost-efficient passive assembly techniques. We demonstrate a selection of beam-shaping elements at chip and fibre facets, achieving coupling efficiencies of up to 88% between edge-emitting lasers and single-mode fibres. We also realize printed free-form mirrors that simultaneously adapt beam shape and propagation direction, and we explore multi-lens systems for beam expansion. The concept paves the way to automated assembly of photonic multi-chip systems with unprecedented performance and versatility.

A simple modern correctness condition for a space-based high-performance multiprocessor

NASA Technical Reports Server (NTRS)

Probst, David K.; Li, Hon F.

1992-01-01

A number of U.S. national programs, including space-based detection of ballistic missile launches, envisage putting significant computing power into space. Given sufficient progress in low-power VLSI, multichip-module packaging and liquid-cooling technologies, we will see design of high-performance multiprocessors for individual satellites. In very high speed implementations, performance depends critically on tolerating large latencies in interprocessor communication; without latency tolerance, performance is limited by the vastly differing time scales in processor and data-memory modules, including interconnect times. The modern approach to tolerating remote-communication cost in scalable, shared-memory multiprocessors is to use a multithreaded architecture, and alter the semantics of shared memory slightly, at the price of forcing the programmer either to reason about program correctness in a relaxed consistency model or to agree to program in a constrained style. The literature on multiprocessor correctness conditions has become increasingly complex, and sometimes confusing, which may hinder its practical application. We propose a simple modern correctness condition for a high-performance, shared-memory multiprocessor; the correctness condition is based on a simple interface between the multiprocessor architecture and a high-performance, shared-memory multiprocessor; the correctness condition is based on a simple interface between the multiprocessor architecture and the parallel programming system.

A microvascular compartment model validated using 11C-methylglucose liver PET in pigs

NASA Astrophysics Data System (ADS)

Munk, Ole L.; Keiding, Susanne; Baker, Charles; Bass, Ludvik

2018-01-01

The standard compartment model (CM) is widely used to analyse dynamic PET data. The CM is fitted to time-activity curves to estimate rate constants that describe the transport of a tracer between well-mixed compartments. The aim of this study was to develop and validate a more realistic microvascular compartment model (MCM) that includes capillary tracer concentration gradients, backflux from cells into the perfused capillaries and multiple re-uptakes during the passage through a capillary. The MCM incorporates only parameters with clear physiological meaning, it is easy to implement, and it does not require numerical solution. We compared the MCM and CM for the analysis of 3 min dynamic PET data of pig livers (N  =  5) following injection of 11C-methylglucose. During PET scans, the tracer concentrations in blood were measured in the abdominal aorta, portal vein and liver vein by manual sampling. We found that the MCM outperformed the CM and that dynamic PET data include information which cannot be extracted using standard CM. The MCM fitted dynamic PET data better than the CM (Akaike values were 46  ±  4 for best MCM fits, and 82  ±  8 for best CM fits; mean  ±  standard deviation) and extracted physiologically reasonable parameter estimates such as blood perfusion that were in agreement with independent measurements. The difference between model-independent perfusion estimates and the best MCM perfusion estimates was  -0.01  ±  0.05 ml/ml/min, whereas the difference was 0.30  ±  0.13 ml/ml/min using the CM. In addition, the MCM predicted the time course of concentrations in the liver vein, a prediction fundamentally unobtainable using the CM as it does not return tracer backflux from cells to capillary blood. The results demonstrate the benefit of using models that include more physiology and that models including concentration gradients should be preferred when analysing the blood-cell exchange of any tracer in any capillary bed.

Learning biology through connecting mathematics to scientific mechanisms: Student outcomes and teacher supports

NASA Astrophysics Data System (ADS)

Schuchardt, Anita

Integrating mathematics into science classrooms has been part of the conversation in science education for a long time. However, studies on student learning after incorporating mathematics in to the science classroom have shown mixed results. Understanding the mixed effects of including mathematics in science has been hindered by a historical focus on characteristics of integration tangential to student learning (e.g., shared elements, extent of integration). A new framework is presented emphasizing the epistemic role of mathematics in science. An epistemic role of mathematics missing from the current literature is identified: use of mathematics to represent scientific mechanisms, Mechanism Connected Mathematics (MCM). Building on prior theoretical work, it is proposed that having students develop mathematical equations that represent scientific mechanisms could elevate their conceptual understanding and quantitative problem solving. Following design and implementation of an MCM unit in inheritance, a large-scale quantitative analysis of pre and post implementation test results showed MCM students, compared to traditionally instructed students) had significantly greater gains in conceptual understanding of mathematically modeled scientific mechanisms, and their ability to solve complex quantitative problems. To gain insight into the mechanism behind the gain in quantitative problem solving, a small-scale qualitative study was conducted of two contrasting groups: 1) within-MCM instruction: competent versus struggling problem solvers, and 2) within-competent problem solvers: MCM instructed versus traditionally instructed. Competent MCM students tended to connect their mathematical inscriptions to the scientific phenomenon and to switch between mathematical and scientifically productive approaches during problem solving in potentially productive ways. The other two groups did not. To address concerns about teacher capacity presenting barriers to scalability of MCM approaches, the types and amount of teacher support needed to achieve these types of student learning gains were investigated. In the context of providing teachers with access to educative materials, students achieved learning gains in both areas in the absence of face-to-face teacher professional development. However, maximal student learning gains required the investment of face-to-face professional development. This finding can govern distribution of scarce resources, but does not preclude implementation of MCM instruction even where resource availability does not allow for face-to-face professional development.

32 CFR 152.1 - Purpose.

Code of Federal Regulations, 2010 CFR

2010-07-01

... by the President in Executive Order 12473 that the Manual for Courts-Martial (MCM), United States... to the MCM and proposing legislation to amend the Uniform Code of Military Justice (UCMJ) (10 U.S.C...

The JPL telerobotic Manipulator Control and Mechanization (MCM) subsystem

NASA Technical Reports Server (NTRS)

Hayati, Samad; Lee, Thomas S.; Tso, Kam; Backes, Paul; Kan, Edwin; Lloyd, J.

1989-01-01

The Manipulator Control and Mechanization (MCM) subsystem of the telerobot system provides the real-time control of the robot manipulators in autonomous and teleoperated modes and real time input/output for a variety of sensors and actuators. Substantial hardware and software are included in this subsystem which interfaces in the hierarchy of the telerobot system with the other subsystems. The other subsystems are: run time control, task planning and reasoning, sensing and perception, and operator control subsystem. The architecture of the MCM subsystem, its capabilities, and details of various hardware and software elements are described. Important improvements in the MCM subsystem over the first version are: dual arm coordinated trajectory generation and control, addition of integrated teleoperation, shared control capability, replacement of the ultimate controllers with motor controllers, and substantial increase in real time processing capability.

Investigation of radiative interaction in laminar flows using Monte Carlo simulation

NASA Technical Reports Server (NTRS)

Liu, Jiwen; Tiwari, S. N.

1993-01-01

The Monte Carlo method (MCM) is employed to study the radiative interactions in fully developed laminar flow between two parallel plates. Taking advantage of the characteristics of easy mathematical treatment of the MCM, a general numerical procedure is developed for nongray radiative interaction. The nongray model is based on the statistical narrow band model with an exponential-tailed inverse intensity distribution. To validate the Monte Carlo simulation for nongray radiation problems, the results of radiative dissipation from the MCM are compared with two available solutions for a given temperature profile between two plates. After this validation, the MCM is employed to solve the present physical problem and results for the bulk temperature are compared with available solutions. In general, good agreement is noted and reasons for some discrepancies in certain ranges of parameters are explained.

MCM5: a new actor in the link between DNA replication and Meier-Gorlin syndrome.

PubMed

Vetro, Annalisa; Savasta, Salvatore; Russo Raucci, Annalisa; Cerqua, Cristina; Sartori, Geppo; Limongelli, Ivan; Forlino, Antonella; Maruelli, Silvia; Perucca, Paola; Vergani, Debora; Mazzini, Giuliano; Mattevi, Andrea; Stivala, Lucia Anna; Salviati, Leonardo; Zuffardi, Orsetta

2017-05-01

Meier-Gorlin syndrome (MGORS) is a rare disorder characterized by primordial dwarfism, microtia, and patellar aplasia/hypoplasia. Recessive mutations in ORC1, ORC4, ORC6, CDT1, CDC6, and CDC45, encoding members of the pre-replication (pre-RC) and pre-initiation (pre-IC) complexes, and heterozygous mutations in GMNN, a regulator of cell-cycle progression and DNA replication, have already been associated with this condition. We performed whole-exome sequencing (WES) in a patient with a clinical diagnosis of MGORS and identified biallelic variants in MCM5. This gene encodes a subunit of the replicative helicase complex, which represents a component of the pre-RC. Both variants, a missense substitution within a conserved domain critical for the helicase activity, and a single base deletion causing a frameshift and a premature stop codon, were predicted to be detrimental for the MCM5 function. Although variants of MCM5 have never been reported in specific human diseases, defect of this gene in zebrafish causes a phenotype of growth restriction overlapping the one associated with orc1 depletion. Complementation experiments in yeast showed that the plasmid carrying the missense variant was unable to rescue the lethal phenotype caused by mcm5 deletion. Moreover cell-cycle progression was delayed in patient's cells, as already shown for mutations in the ORC1 gene. Altogether our findings support the role of MCM5 as a novel gene involved in MGORS, further emphasizing that this condition is caused by impaired DNA replication.

Tetracycline-Containing MCM-41 Mesoporous Silica Nanoparticles for the Treatment of Escherichia coli.

PubMed

Koneru, Bhuvaneswari; Shi, Yi; Wang, Yu-Chieh; Chavala, Sai H; Miller, Michael L; Holbert, Brittany; Conson, Maricar; Ni, Aiguo; Di Pasqua, Anthony J

2015-10-30

Tetracycline (TC) is a well-known broad spectrum antibiotic, which is effective against many Gram positive and Gram negative bacteria. Controlled release nanoparticle formulations of TC have been reported, and could be beneficial for application in the treatment of periodontitis and dental bone infections. Furthermore, TC-controlled transcriptional regulation systems (Tet-on and Tet-off) are useful for controlling transgene expression in vitro and in vivo for biomedical research purposes; controlled TC release systems could be useful here, as well. Mesoporous silica nanomaterials (MSNs) are widely studied for drug delivery applications; Mobile crystalline material 41 (MCM-41), a type of MSN, has a mesoporous structure with pores forming channels in a hexagonal fashion. We prepared 41 ± 4 and 406 ± 55 nm MCM-41 mesoporous silica nanoparticles and loaded TC for controlled dug release; TC content in the TC-MCM-41 nanoparticles was 18.7% and 17.7% w/w, respectively. Release of TC from TC-MCM-41 nanoparticles was then measured in phosphate-buffered saline (PBS), pH 7.2, at 37 °C over a period of 5 h. Most antibiotic was released from both over this observation period; however, the majority of TC was released over the first hour. Efficacy of the TC-MCM-41 nanoparticles was then shown to be superior to free TC against Escherichia coli (E. coli) in culture over a 24 h period, while blank nanoparticles had no effect.

The Cdc45/RecJ-like protein forms a complex with GINS and MCM, and is important for DNA replication in Thermococcus kodakarensis

PubMed Central

Nagata, Mariko; Yamagami, Takeshi; Ogino, Hiromi; Simons, Jan-Robert; Kanai, Tamotsu; Atomi, Haruyuki

2017-01-01

Abstract The archaeal minichromosome maintenance (MCM) has DNA helicase activity, which is stimulated by GINS in several archaea. In the eukaryotic replicative helicase complex, Cdc45 forms a complex with MCM and GINS, named as CMG (Cdc45-MCM-GINS). Cdc45 shares sequence similarity with bacterial RecJ. A Cdc45/RecJ-like protein from Thermococcus kodakarensis shows a bacterial RecJ-like exonuclease activity, which is stimulated by GINS in vitro. Therefore, this archaeal Cdc45/RecJ is designated as GAN, from GINS-associated nuclease. In this study, we identified the CMG-like complex in T. kodakarensis cells. The GAN·GINS complex stimulated the MCM helicase, but MCM did not affect the nuclease activity of GAN in vitro. The gene disruption analysis showed that GAN was non-essential for its viability but the Δgan mutant did not grow at 93°C. Furthermore, the Δgan mutant showed a clear retardation in growth as compared with the parent cells under optimal conditions at 85°C. These deficiencies were recovered by introducing the gan gene encoding the nuclease deficient GAN protein back to the genome. These results suggest that the replicative helicase complex without GAN may become unstable and ineffective in replication fork progression. The nuclease activity of GAN is not related to the growth defects of the Δgan mutant cells. PMID:28977567

Role of neutrophilic inflammation in ozone-induced epithelial alterations in the nasal airways of rats

NASA Astrophysics Data System (ADS)

Cho, Hye Youn

Ozone is a principal oxidant air pollutant in photochemical smog. Epithelial cells lining the centriacinar region of lung and the proximal aspects of nasal passage are primary target sites for ozone-induced injury in laboratory animals. Acute exposure of rats to high ambient concentrations of ozone (e.g., 0.5 ppm) results in neutrophilic inflammation, epithelial hyperplasia and mucous cell metaplasia (MCM) in the nasal transitional epithelium (NTE) lining the proximal nasal airways. The principal purpose of the present study was to investigate the role of pre-metaplastic cellular responses, especially neutrophilic inflammation, in the pathogenesis of ozone-induced MCM in rat NTE. For this purpose, three specific hypotheses-based whole-animal inhalation studies were conducted. Male F344/N rats were exposed in whole-body inhalation chambers to 0 (filtered air) or 0.5 ppm ozone for 1-3 days (8 h/day). Histochemical, immunochemical, molecular and morphometric techniques were used to investigate the ozone-induced cellular and molecular events in the NTE. Two in vitro studies were also conducted to examine the effects of ozone-inducible cytokines (i.e., tumor necrosis factor-alpha; TNF- a, and interleukin-6; IL-6) on mucin gene (rMuc-5AC) expression. Ozone induced a rapid increase of rMuc-5AC mRNA in nasal tissues within hours after the start of exposure. It preceded the appearance of MCM, and persisted with MCM. Ozone-induced neutrophilic inflammation accompanied the mucin gene upregulation, but was resolved when MCM first appeared in the NTE. Antibody-mediated depletion of circulating neutrophils attenuated ozone-induced MCM, although it did not affect the ozone-induced epithelial hyperplasia and mucin mRNA upregulation. In another study, it was found that preexisting neutrophilic rhinitis induced by endotoxin augmented the ozone-induced MCM. However, pre-existing rhinitis did not alter the severity of ozone-induced epithelial hyperplasia and mucin gene upregulation. Ozone also induced rapid increases in TNF-a and IL-6 mRNAs in nasal tissues. In addition, exogenous TNF-α and IL- 6 induced increases in mucin mRNA in nasal tissues in vitro. In conclusion, though ozone alone is sufficient to induce epithelial proliferation and mucin gene upregulation which are early NTE cell events prior to the development of MCM, neutrophilic inflammation is essential for full phenotypic expression of MCM. TNF-α and IL-6 may be putative mediators of the ozone-induced upregulation of mucin mRNA in the NTE.

Cryo-EM structure of a helicase loading intermediate containing ORC–Cdc6–Cdt1–MCM2-7 bound to DNA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Jingchuan; Evrin, Cecile; Samel, Stefan A.

2013-07-14

In eukaryotes, the Cdt1-bound replicative helicase core MCM2-7 is loaded onto DNA by the ORC–Cdc6 ATPase to form a prereplicative complex (pre-RC) with an MCM2-7 double hexamer encircling DNA. Using purified components in the presence of ATP-γS, we have captured in vitro an intermediate in pre-RC assembly that contains a complex between the ORC–Cdc6 and Cdt1–MCM2-7 heteroheptamers called the OCCM. Cryo-EM studies of this 14-subunit complex reveal that the two separate heptameric complexes are engaged extensively, with the ORC–Cdc6 N-terminal AAA+ domains latching onto the C-terminal AAA+ motor domains of the MCM2-7 hexamer. The conformation of ORC–Cdc6 undergoes a concertedmore » change into a right-handed spiral with helical symmetry that is identical to that of the DNA double helix. The resulting ORC–Cdc6 helicase loader shows a notable structural similarity to the replication factor C clamp loader, suggesting a conserved mechanism of action.« less

Innovative 3D Visualization of Electro-optic Data for MCM

DTIC Science & Technology

2001-09-30

The long-term goal is to develop innovative methods for transforming data taken by electro - optic and acoustic MCM sensors into graphical representations better suited to human interpretation, specifically to aid mine classification.

32 CFR 152.4 - Responsibilities.

Code of Federal Regulations, 2010 CFR

2010-07-01

... changes to the MCM under OMB Circular A-19. 1 1 Available at http://www.whitehouse.gov/omb/circulars/index... historical records, and for publication of the updated editions of the MCM to be distributed throughout the...

Photoactive Nitric Oxide Delivery Systems based on Metal Nitrosyl-Biomaterial Composites

NASA Astrophysics Data System (ADS)

Heilman, Brandon James

Gaseous NO has been recognized as a potent antibiotic even against highly drug-resistant pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) in both animal and human studies. However, difficulties in the delivery of the toxic (and reactive) gas demands innovative techniques to deliver NO in a controlled manner to malignant sites throughout the body. Metal nitrosyls reported by our group have demonstrated rapid NO release under the complete control of visible and NIR light. Careful incorporation of these photoactive nitrosyls into polymer matrices has afforded a set of nitrosyl-polymer composites in order to localize the NO-donors at a targeted site, ensure reliable NO release kinetics in vivo, and prevent potentially cytotoxic interactions of the metal nitrosyl or its reaction-products with the treatment site. The work presented in this thesis was pursued to derive clinically relevant NO-delivery systems and demonstrate their utility for the treatment of infection. In chapter 2, an NO-releasing polyurethane film (PUX-NO) is described with dispersed xerogel particles containing up to 3 mol% of [Mn(PaPy 3)(NO)](ClO4) entrapped in a silica matrix and swelled with excess moisture. The polyurethane based xerogel-nitrosyl (PUX-NO) films demonstrated rapid NO photorelease upon illumination with low-power visible light which was sufficient to eradicate clinically relevant loads (105 CFU mL-1 ) of several gram-positive and gram-negative pathogenic bacteria, including a strain of methicillin-resistant of S. aureus. The results of this study suggest that PUX-NO films are suitable for use as a NO-releasing occlusive film for the treatment of skin and soft-tissue infections or chronic, non-healing wounds. Since the NO-release rate from the films can be modulated by simple adjustment of the intensity of the light source, the films could be used to first clear the microbial burden from the wound site using high fluxes of NO, and then, provide a moderate, sustained flux of NO in order to accelerate the wound healing process and mitigate the potential for recurrent infections. Chapter 3 details the incorporation of a photoactive Mn nitrosyl in the mesopores of a MCM-41 type silicate to afford {Mn-NO} MCM-41. To increase the interaction between the nitrosyl and the MCM-41 pore walls, an aluminosilicate-based material (Al-MCM-41) was used with 3 mol% AlIII substituted for tetrahedral SiIV sites, which introduced negative point charges capable of electrostatically binding the cationic nitrosyl. Homegenous loading of the Mn nitrosyl (up to 25 wt.%) throughout the hexagonally packed, uni-dimensional mesopores of the Al-MCM-41 particles was determined using various analytical techniques including ICP-MS, FAAS, PXRD, N2 sorption isometry, UV-vis DRS, FTIR, and SEM-EDX. Exposure of {Mn-NO} Al-MCM-41 to visible light of similar intensity to sunlight on a bright day (100 mW cm-2) released high fluxes of NO that effectively eradicated a multi-drug resistant strain of Acinetobacter baumannii.. In another study, described in Chapter 4, the powdery material was used to demonstrate the effect of NO on the dimorphic fungal pathogen, Candida albicans. Since the virulence of C. albicans is dependent on the ability of the fungus to switch growth from an ovoid yeast form to an elongated hyphal form, careful studies of the dose-dependent effect of NO released from {Mn-NO} Al-MCM-41 on morphologically pure cultures of C. albicans in the yeast and hyphal forms have revealed that the hyphal form is more susceptible to NO. Results of this work suggest that photo-activated NO-donating materials of this type could prevent commensal populations of C. albicans from invading vulnerable tissue by blocking the over-growth of the tissue penetrating hyphal form of the fungus.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khezri, Khezrollah, E-mail: kh.khezri@ut.ac.ir; Roghani-Mamaqani, Hossein

Graphical abstract: Effect of mesoporous silica nanoparticles (MCM-41) on the activator generated by electron transfer for atom transfer radical polymerization (AGET ATRP) is investigated. Decrement of conversion and number average molecular weight and also increment of polydispersity index (PDI) values are three main results of addition of MCM-41 nanoparticles. Incorporation of MCM-41 nanoparticles in the polystyrene matrix can clearly increase thermal stability and decrease glass transition temperature of the nanocomposites. - Highlights: • Spherical morphology, hexagonal structure, and high surface area with regular pore diameters of the synthesized MCM-41 nanoparticles are examined. • AGET ATRP of styrene in the presencemore » of MCM-41 nanoparticles is performed. • Effect of MCM-41 nanoparticles addition on the polymerization rate, conversion and molecular weights of the products are discussed. • Improvement in thermal stability of the nanocomposites and decreasing T{sub g} values was also observed by incorporation of MCM-41 nanoparticles. - Abstract: Activator generated by electron transfer for atom transfer radical polymerization was employed to synthesize well-defined mesoporous silica nanoparticles/polystyrene composites. Inherent features of spherical mesoporous silica nanoparticles were evaluated by nitrogen adsorption/desorption isotherm, X-ray diffraction and scanning electron microscopy analysis techniques. Conversion and molecular weight evaluations were carried out using gas and size exclusion chromatography respectively. By the addition of only 3 wt% mesoporous silica nanoparticles, conversion decreases from 81 to 58%. Similarly, number average molecular weight decreases from 17,116 to 12,798 g mol{sup −1}. However, polydispersity index (PDI) values increases from 1.24 to 1.58. A peak around 4.1–4.2 ppm at proton nuclear magnetic resonance spectroscopy results clearly confirms the living nature of the polymerization. Thermogravimetric analysis shows that thermal stability of the nanocomposites increases by adding nanoparticles content. Decrease of glass transition temperature is also demonstrated by the addition of 3 wt% of silica nanoparticles according to the differential scanning calorimetry results.« less

Vanadium-substituted heteropolyacids immobilized on amine- functionalized mesoporous MCM-41: A recyclable catalyst for selective oxidation of alcohols with H{sub 2}O{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong, Xinbo; Wang, Danjun; College of Chemistry Chemical Engineering, Yanan University, Shaanxi Key Laboratory of Chemical Reaction Engineering, Yan'an 716000

2014-09-15

Graphical abstract: Vanadium-substituted phosphotungstic acids are immobilized on amine- functionalized mesoporous MCM-41 and the hybrid catalyst is proved to be a highly efficient solid catalyst for the oxidation of aromatic alcohols to the corresponding carbonyl compounds with H{sub 2}O{sub 2}, featured by the high conversion and selectivity, easy recovery, and quite steady reuse. - Highlights: • Vanadium-substituted phosphotungstic acid immobilized on amine-functionalized mesoporous MCM-41 are prepared. • HPAs were fixed on the inner surface of mesoporous MCM-41 by chemical bonding to aminosilane groups. • The hybrid catalyst showed much higher catalytic activity than the pure HPAs. • The hybrid catalystmore » is a highly efficient recyclable solid catalyst for the selective oxidation of aromatic alcohols. - Abstract: New hybrid materials of vanadium-substituted phosphotungstic acids (VHPW) immobilized on amine-functionalized mesoporous MCM-41 (VHPW/MCM-41/NH{sub 2}) are prepared and characterized by FT-IR, XRD, N{sub 2} adsorption, elemental analysis, SEM and TEM for their structural integrity and physicochemical properties. It is found that the structure of the heteropolyacids is retained upon immobilization over mesoporous materials. The catalytic activities of these hybrid materials are tested in the selective oxidation of alcohols to the carbonyl products with 30% aqueous H{sub 2}O{sub 2} as oxidant in toluene. The catalytic activities of different number of vanadium-substituted phosphotungstic acid are investigated, and among the catalysts, H{sub 5}[PV{sub 2}W{sub 10}O{sub 40}] immobilized on amine-functionalized MCM-41 exhibits the highest activity with 97% conversion and 99% selectivity in the oxidation of benzyl alcohol to benzaldehyde. The hybrid catalyst is proved to be a highly efficient recyclable solid catalyst for the selective oxidation of aromatic alcohols to the corresponding aldehydes with H{sub 2}O{sub 2}.« less

Computation of groundwater resources and recharge in Chithar River Basin, South India.

PubMed

Subramani, T; Babu, Savithri; Elango, L

2013-01-01

Groundwater recharge and available groundwater resources in Chithar River basin, Tamil Nadu, India spread over an area of 1,722 km(2) have been estimated by considering various hydrological, geological, and hydrogeological parameters, such as rainfall infiltration, drainage, geomorphic units, land use, rock types, depth of weathered and fractured zones, nature of soil, water level fluctuation, saturated thickness of aquifer, and groundwater abstraction. The digital ground elevation models indicate that the regional slope of the basin is towards east. The Proterozoic (Post-Archaean) basement of the study area consists of quartzite, calc-granulite, crystalline limestone, charnockite, and biotite gneiss with or without garnet. Three major soil types were identified namely, black cotton, deep red, and red sandy soils. The rainfall intensity gradually decreases from west to east. Groundwater occurs under water table conditions in the weathered zone and fluctuates between 0 and 25 m. The water table gains maximum during January after northeast monsoon and attains low during October. Groundwater abstraction for domestic/stock and irrigational needs in Chithar River basin has been estimated as 148.84 MCM (million m(3)). Groundwater recharge due to monsoon rainfall infiltration has been estimated as 170.05 MCM based on the water level rise during monsoon period. It is also estimated as 173.9 MCM using rainfall infiltration factor. An amount of 53.8 MCM of water is contributed to groundwater from surface water bodies. Recharge of groundwater due to return flow from irrigation has been computed as 147.6 MCM. The static groundwater reserve in Chithar River basin is estimated as 466.66 MCM and the dynamic reserve is about 187.7 MCM. In the present scenario, the aquifer is under safe condition for extraction of groundwater for domestic and irrigation purposes. If the existing water bodies are maintained properly, the extraction rate can be increased in future about 10% to 15%.

Elongator Complex Influences Telomeric Gene Silencing and DNA Damage Response by Its Role in Wobble Uridine tRNA Modification

PubMed Central

Chen, Changchun; Huang, Bo; Eliasson, Mattias; Rydén, Patrik; Byström, Anders S.

2011-01-01

Elongator complex is required for formation of the side chains at position 5 of modified nucleosides 5-carbamoylmethyluridine (ncm5U34), 5-methoxycarbonylmethyluridine (mcm5U34), and 5-methoxycarbonylmethyl-2-thiouridine (mcm5s2U34) at wobble position in tRNA. These modified nucleosides are important for efficient decoding during translation. In a recent publication, Elongator complex was implicated to participate in telomeric gene silencing and DNA damage response by interacting with proliferating cell nuclear antigen (PCNA). Here we show that elevated levels of tRNALys s2 UUU, tRNAGln s2 UUG, and tRNAGlu s2 UUC, which in a wild-type background contain the mcm5s2U nucleoside at position 34, suppress the defects in telomeric gene silencing and DNA damage response observed in the Elongator mutants. We also found that the reported differences in telomeric gene silencing and DNA damage response of various elp3 alleles correlated with the levels of modified nucleosides at U34. Defects in telomeric gene silencing and DNA damage response are also observed in strains with the tuc2Δ mutation, which abolish the formation of the 2-thio group of the mcm5s2U nucleoside in tRNALys mcm5s2UUU, tRNAGln mcm5s2UUG, and tRNAGlu mcm5s2UUC. These observations show that Elongator complex does not directly participate in telomeric gene silencing and DNA damage response, but rather that modified nucleosides at U34 are important for efficient expression of gene products involved in these processes. Consistent with this notion, we found that expression of Sir4, a silent information regulator required for assembly of silent chromatin at telomeres, was decreased in the elp3Δ mutants. PMID:21912530

Amplified 7q21-22 gene MCM7 and its intronic miR-25 suppress COL1A2 associated genes to sustain intestinal gastric cancer features.

PubMed

Tamilzhalagan, Sembulingam; Rathinam, Dhanasekaran; Ganesan, Kumaresan

2017-06-01

Frequent amplification of 7q21-22 genomic region is known in gastric cancer. Multiple genes including SHFM1, MCM7, and COL1A2 were reported to be the potential cancer candidate genes of this 20 Mb amplicon. This amplicon has two polycistrionic miRNA clusters and in the present study, miR-106b-25 cluster located in intron-13 of MCM7 was identified to express in gastric tumors. Among the 7q21-22 candidate genes, SHFM1 and MCM7 are expressed in intestinal type gastric tumors, whereas COL1A2 is expressed in diffuse type gastric tumors. Across gastric tumors, miR-25 was identified to co-express with MCM7 and SHFM1. On the other hand, negative correlation was observed between miR-25 and COL1A2 expression. miR-25 originating from MCM7 was found capable of selectively targeting the adjacent gene COL1A2. Silencing of miR-25 was found capable of elevating the expression of COL1A2 and inhibiting E-cadherin expression, revealing the diffuse type gastric cancer suppressive role conferred by miR-25. miR-25 was also found to suppress p53, and activate c-Src revealing its intestinal type gastric cancer associated oncogenic functions. Genome-wide expression profiling upon miR-25 silencing reveals that miR-25 is capable of suppressing 40 genes which are co-expressed with COL1A2, involved in epithelial to mesenchymal transition and angiogenesis which are the typical diffuse type gastric cancer features. The results clearly demonstrate 7q21-22 amplification, MCM7, and its intronic miR-25 are the major molecular switches involved in the complex oncogenic circuits of gastric cancer. © 2017 Wiley Periodicals, Inc.

ORC1/CDC6 and MCM7 distinct associate with chromatin through Trypanosoma cruzi life cycle.

PubMed

Calderano, Simone; Godoy, Patricia; Soares, Daiane; Sant'Anna, Osvaldo Augusto; Schenkman, Sergio; Elias, M Carolina

2014-02-01

Trypanosoma cruzi alternates between replicative and non-replicative stages. We analyzed the expression of components of the pre-replication machinery TcORC1/CDC6 and TcMCM7 and their interaction with DNA in all T. cruzi stages. TcORC1/CDC6 remains in the nuclear space during all stages of the life cycle and interacts with DNA in the replicative stages; however, it does not bind to DNA in the non-replicative forms. Moreover, TcMCM7 is not present in the non-replicative stages. These data suggest that the lacking of DNA replication during the T. cruzi life cycle may be a consequence of the blocking of TcORC1/CDC6-DNA interaction and of the down regulation of the TcMCM7 expression. Copyright © 2014 Elsevier B.V. All rights reserved.

Regulated Eukaryotic DNA Replication Origin Firing with Purified Proteins

PubMed Central

Yeeles, Joseph T.P.; Deegan, Tom D.; Janska, Agnieszka; Early, Anne; Diffley, John F. X.

2016-01-01

Eukaryotic cells initiate DNA replication from multiple origins, which must be tightly regulated to promote precise genome duplication in every cell cycle. To accomplish this, initiation is partitioned into two temporally discrete steps: a double hexameric MCM complex is first loaded at replication origins during G1 phase, and then converted to the active CMG (Cdc45, MCM, GINS) helicase during S phase. Here we describe the reconstitution of budding yeast DNA replication initiation with 16 purified replication factors, made from 42 polypeptides. Origin-dependent initiation recapitulates regulation seen in vivo. Cyclin dependent kinase (CDK) inhibits MCM loading by phosphorylating the origin recognition complex (ORC) and promotes CMG formation by phosphorylating Sld2 and Sld3. Dbf4 dependent kinase (DDK) promotes replication by phosphorylating MCM, and can act either before or after CDK. These experiments define the minimum complement of proteins, protein kinase substrates and co-factors required for regulated eukaryotic DNA replication. PMID:25739503

Regulated eukaryotic DNA replication origin firing with purified proteins.

PubMed

Yeeles, Joseph T P; Deegan, Tom D; Janska, Agnieszka; Early, Anne; Diffley, John F X

2015-03-26

Eukaryotic cells initiate DNA replication from multiple origins, which must be tightly regulated to promote precise genome duplication in every cell cycle. To accomplish this, initiation is partitioned into two temporally discrete steps: a double hexameric minichromosome maintenance (MCM) complex is first loaded at replication origins during G1 phase, and then converted to the active CMG (Cdc45-MCM-GINS) helicase during S phase. Here we describe the reconstitution of budding yeast DNA replication initiation with 16 purified replication factors, made from 42 polypeptides. Origin-dependent initiation recapitulates regulation seen in vivo. Cyclin-dependent kinase (CDK) inhibits MCM loading by phosphorylating the origin recognition complex (ORC) and promotes CMG formation by phosphorylating Sld2 and Sld3. Dbf4-dependent kinase (DDK) promotes replication by phosphorylating MCM, and can act either before or after CDK. These experiments define the minimum complement of proteins, protein kinase substrates and co-factors required for regulated eukaryotic DNA replication.

Two subunits of human ORC are dispensable for DNA replication and proliferation.

PubMed

Shibata, Etsuko; Kiran, Manjari; Shibata, Yoshiyuki; Singh, Samarendra; Kiran, Shashi; Dutta, Anindya

2016-12-01

The six-subunit Origin Recognition Complex (ORC) is believed to be an essential eukaryotic ATPase that binds to origins of replication as a ring-shaped heterohexamer to load MCM2-7 and initiate DNA replication. We have discovered that human cell lines in culture proliferate with intact chromosomal origins of replication after disruption of both alleles of ORC2 or of the ATPase subunit, ORC1 . The ORC1 or ORC2 -depleted cells replicate with decreased chromatin loading of MCM2-7 and become critically dependent on another ATPase, CDC6, for survival and DNA replication. Thus, either the ORC ring lacking a subunit, even its ATPase subunit, can load enough MCM2-7 in partnership with CDC6 to initiate DNA replication, or cells have an ORC-independent, CDC6-dependent mechanism to load MCM2-7 on origins of replication.

Synthesis of nanosize MCM-41 loaded with TiO 2 and study of its photocatalytic activity

NASA Astrophysics Data System (ADS)

Sadjadi, M. S.; Farhadyar, N.; Zare, K.

2009-07-01

In recent years, nanosized mesoporous materials have received significant attention due to their impact in different processes. Several diverse applications of these materials, e.g. high density magnetic recording, magnetic fluids, magnetic refrigeration as well as in photocatalysis, solar cells, photosensors, have triggered considerable research activities in the area of nanotechnology. In this work, nanosize MCM-41 was synthesized and loaded then with TiO 2 using tetra butoxy titanium (TBT). As prepared TiO 2 loaded materials was investigated by using X-ray diffraction (XRD), Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR). The photocatalytic activity of the prepared TiO 2 loaded MCM-41 was finally evaluated by the degradation of methyl orange under irradiation of UV light. The result showed that TiO 2 loaded on nanosize MCM-41 has higher photocatalytic activity than that of TiO 2.

Key factor affecting the structural and textural properties of ZSM-5/MCM-41 composite

NASA Astrophysics Data System (ADS)

Boukoussa, Bouhadjar; Aouad, Nafissa; Hamacha, Rachida; Bengueddach, Abdelkader

2015-03-01

ZSM-5/MCM-41 micro/mesoporous composite materials were synthesized by the hydrothermal technique with alkali-treated ZSM-5 zeolite as source of silica and aluminum and characterized by various physico-chemical techniques such as X-ray diffraction (XRD), nitrogen sorption at 77 K, transmission electronic microscopy (TEM), FTIR spectroscopy and NH3 temperature programmed desorption (TPD) techniques. The effect of concentration of CTAB in the synthesis of these solids has been investigated, the mesopore volume, surface area and surface acidity decrease with increasing the concentration of CTAB. Increasing the CTAB concentration causes the recrystallization of zeolite ZSM-5 and it disadvantage the formation of mesoporous materials MCM-41. The catalytic activity of ZSM-5/MCM-41 materials has been evaluated in the Friedel-Crafts acylation of anisole with benzoyl chloride as alkylating agent. The results revealed the reaction to be influenced by surface area, pore volume and surface acidity.

Effect of SiO2/Al2O3 Ratio on Micro-Mesopore Formation for Pt/Beta-MCM-41 via NaOH Treatment and the Catalytic Performance in N-heptane Hydro isomerization

NASA Astrophysics Data System (ADS)

Gao, Li; Shi, Zhiyuan; Liu, Yingming; Zhao, Yuanshou; Liu, Qinghua; Xu, Chengguo; Bai, Peng; Yan, Zifeng

2018-01-01

Micro-mesoporous composite material Beta-MCM-41(BM) were hydrothermally synthesized by treating parent beta with molar SiO2/Al2O3 ratios of 12.5, 20 and 30 as precursors. The influence of SiO2/Al2O3 ratio of zeolite beta on effective micro-mesoporous composite formation was studied by investigating the crystallinity, morphology, chemical composition, acidity and textural property of Beta-MCM-41 through XRD, nitrogen adsorption, SEM, TEM, NH3-TPD, FTIR and Pyridine-FTIR. The catalytic performance was evaluated in terms of n-heptane hydro isomerization. The results demonstrated that Beta-MCM-41 supported Pt catalysts showed higher selectivity to isoheptanes than Pt/Beta. It was attributed to the superiorities of the pore structure and mesoporous accelerated the diffusion of larger molecules of isoheptanes.

Manganese porphyrin immobilized on magnetic MCM-41 nanoparticles as an efficient and reusable catalyst for alkene oxidations with sodium periodate

NASA Astrophysics Data System (ADS)

Hajian, Robabeh; Ehsanikhah, Amin

2018-01-01

This study describes the immobilization of tetraphenylporphyrinatomanganese(III) chloride, (MnPor), onto imidazole functionalized MCM-41 with magnetite nanoparticle core (Fe3O4@MCM-41-Im). The resultant material (Fe3O4@MCM-41-Im@MnPor) was characterized by X-ray diffractometry (XRD), Fourier transform infra-red (FT-IR), diffuse reflectance UV-Vis spectrophotometry (DR UV-Vis), field emission scanning electron microscopy (FESEM), Inductively coupled plasma (ICP), analyzer transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) surface area. This new heterogenized catalyst was applied as an efficient catalyst for the epoxidation of a variety of cyclic and linear olefins with NaIO4 under mild conditions. The prepared catalyst can be easily recovered through the application of an external magnet, and reused several times without any significant decrease in activity and magnetic properties.

DNA Interactions Probed by Hydrogen-Deuterium Exchange (HDX) Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Confirm External Binding Sites on the Minichromosomal Maintenance (MCM) Helicase*

PubMed Central

Graham, Brian W.; Tao, Yeqing; Dodge, Katie L.; Thaxton, Carly T.; Olaso, Danae; Young, Nicolas L.; Marshall, Alan G.

2016-01-01

The archaeal minichromosomal maintenance (MCM) helicase from Sulfolobus solfataricus (SsoMCM) is a model for understanding structural and mechanistic aspects of DNA unwinding. Although interactions of the encircled DNA strand within the central channel provide an accepted mode for translocation, interactions with the excluded strand on the exterior surface have mostly been ignored with regard to DNA unwinding. We have previously proposed an extension of the traditional steric exclusion model of unwinding to also include significant contributions with the excluded strand during unwinding, termed steric exclusion and wrapping (SEW). The SEW model hypothesizes that the displaced single strand tracks along paths on the exterior surface of hexameric helicases to protect single-stranded DNA (ssDNA) and stabilize the complex in a forward unwinding mode. Using hydrogen/deuterium exchange monitored by Fourier transform ion cyclotron resonance MS, we have probed the binding sites for ssDNA, using multiple substrates targeting both the encircled and excluded strand interactions. In each experiment, we have obtained >98.7% sequence coverage of SsoMCM from >650 peptides (5–30 residues in length) and are able to identify interacting residues on both the interior and exterior of SsoMCM. Based on identified contacts, positively charged residues within the external waist region were mutated and shown to generally lower DNA unwinding without negatively affecting the ATP hydrolysis. The combined data globally identify binding sites for ssDNA during SsoMCM unwinding as well as validating the importance of the SEW model for hexameric helicase unwinding. PMID:27044751

Enhanced molecular recognition for imprinted monolithic column containing polyhedral oligomeric silsesquioxanes by dendritic effect of mesoporous molecular sieve scaffolds.

PubMed

Yang, Fang-Fang; Li, Zai-Xuan; Xu, Yu-Jing; Huang, Yan-Ping; Liu, Zhao-Sheng

2018-06-07

The dendritic effect of nano mesoporous molecular sieve was first used to enhance molecular recognition of molecularly imprinted polymers (MIPs)-based polyhedral oligomeric silsesquioxanes (POSS). In this study, the MIPs were made using S-naproxen (S-NAP) as template molecule, 4-vinylpyridine (4-VP) as functional monomer, ethylene glycol dimethacrylate as cross-linker, 1-butyl-3-methylimidazoliumtetrafluoroborate ([BMIM]BF 4 )/DMSO as binary porogens, 1-propylmethacrylate-heptaisobutyl substituted as POSS monomer, and mesoporous molecular sieve (Mobil composition of matter No. 41, MCM-41) as dendritic scaffold. The influence of synthesis parameters on the imprinting effect, including the content of POSS monomer and derivatized MCM-41-MPS, the ratio of template to monomer, and the ratio of binary porogens were also investigated, respectively. The morphology of the polymers was characterized by scanning electron microscopy, nitrogen adsorption, and X-ray powder diffraction. The results showed that POSS&MCM-41-MPS MIP had a stronger imprinting effect with an imprinting factor 6.86, which is approximately 2.4, 2.3, and 3 times than that of POSS MIP, MCM-41-MPS MIP, and conventional MIP, respectively. The increase of affinity might be attributed to impediment of the chain motion of polymer due to improved POSS aggregation and the dipole interaction between the POSS units by introduce of MCM-41-MPS as scaffolds. The resulting POSS&MCM-41-MPS MIP was used as adsorbent for the enrichment of S-NAP in solid-phase extraction with a high recovery of 97.65% and the value of RSD was 0.94%.

Mcm2 deficiency results in short deletions allowing high resolution identification of genes contributing to lymphoblastic lymphoma

PubMed Central

Rusiniak, Michael E.; Kunnev, Dimiter; Freeland, Amy; Cady, Gillian K.; Pruitt, Steven C.

2011-01-01

Mini-chromosome maintenance (Mcm) proteins are part of the replication licensing complex that is loaded onto chromatin during the G1-phase of the cell cycle and required for initiation of DNA replication in the subsequent S-phase. Mcm proteins are typically loaded in excess of the number of locations that are utilized during S-phase. Nonetheless, partial depletion of Mcm proteins leads to cancers and stem cell deficiencies. Mcm2 deficient mice, on a 129Sv genetic background, display a high rate of thymic lymphoblastic lymphoma. Here array comparative genomic hybridization (aCGH) is utilized to characterize the genetic damage accruing in these tumors. The predominant events are deletions averaging less than 0.5 Mb, considerably shorter than observed in prior studies using alternative mouse lymphoma models or human tumors. Such deletions facilitate identification of specific genes and pathways responsible for the tumors. Mutations in many genes that have been implicated in human lymphomas are recapitulated in this mouse model. These features, and the fact that the mutation underlying the accelerated genetic damage does not target a specific gene or pathway a priori, are valuable features of this mouse model for identification of tumor suppressor genes. Genes affected in all tumors include Pten, Tcfe2a, Mbd3 and Setd1b. Notch1 and additional genes are affected in subsets of tumors. The high frequency of relatively short deletions is consistent with elevated recombination between nearby stalled replication forks in Mcm2 deficient mice. PMID:22158038

The Cdc45/RecJ-like protein forms a complex with GINS and MCM, and is important for DNA replication in Thermococcus kodakarensis.

PubMed

Nagata, Mariko; Ishino, Sonoko; Yamagami, Takeshi; Ogino, Hiromi; Simons, Jan-Robert; Kanai, Tamotsu; Atomi, Haruyuki; Ishino, Yoshizumi

2017-10-13

The archaeal minichromosome maintenance (MCM) has DNA helicase activity, which is stimulated by GINS in several archaea. In the eukaryotic replicative helicase complex, Cdc45 forms a complex with MCM and GINS, named as CMG (Cdc45-MCM-GINS). Cdc45 shares sequence similarity with bacterial RecJ. A Cdc45/RecJ-like protein from Thermococcus kodakarensis shows a bacterial RecJ-like exonuclease activity, which is stimulated by GINS in vitro. Therefore, this archaeal Cdc45/RecJ is designated as GAN, from GINS-associated nuclease. In this study, we identified the CMG-like complex in T. kodakarensis cells. The GAN·GINS complex stimulated the MCM helicase, but MCM did not affect the nuclease activity of GAN in vitro. The gene disruption analysis showed that GAN was non-essential for its viability but the Δgan mutant did not grow at 93°C. Furthermore, the Δgan mutant showed a clear retardation in growth as compared with the parent cells under optimal conditions at 85°C. These deficiencies were recovered by introducing the gan gene encoding the nuclease deficient GAN protein back to the genome. These results suggest that the replicative helicase complex without GAN may become unstable and ineffective in replication fork progression. The nuclease activity of GAN is not related to the growth defects of the Δgan mutant cells. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

Loss of Anticodon Wobble Uridine Modifications Affects tRNALys Function and Protein Levels in Saccharomyces cerevisiae

PubMed Central

Klassen, Roland; Grunewald, Pia; Thüring, Kathrin L.; Eichler, Christian; Helm, Mark; Schaffrath, Raffael

2015-01-01

In eukaryotes, wobble uridines in the anticodons of tRNALys UUU, tRNAGlu UUC and tRNAGln UUG are modified to 5-methoxy-carbonyl-methyl-2-thio-uridine (mcm5s2U). While mutations in subunits of the Elongator complex (Elp1-Elp6), which disable mcm5 side chain formation, or removal of components of the thiolation pathway (Ncs2/Ncs6, Urm1, Uba4) are individually tolerated, the combination of both modification defects has been reported to have lethal effects on Saccharomyces cerevisiae. Contrary to such absolute requirement of mcm5s2U for viability, we demonstrate here that in the S. cerevisiae S288C-derived background, both pathways can be simultaneously inactivated, resulting in combined loss of tRNA anticodon modifications (mcm5U and s2U) without a lethal effect. However, an elp3 disruption strain displays synthetic sick interaction and synergistic temperature sensitivity when combined with either uba4 or urm1 mutations, suggesting major translational defects in the absence of mcm5s2U modifications. Consistent with this notion, we find cellular protein levels drastically decreased in an elp3uba4 double mutant and show that this effect as well as growth phenotypes can be partially rescued by excess of tRNALys UUU. These results may indicate a global translational or protein homeostasis defect in cells simultaneously lacking mcm5 and s2 wobble uridine modification that could account for growth impairment and mainly originates from tRNALys UUU hypomodification and malfunction. PMID:25747122

Loss of anticodon wobble uridine modifications affects tRNA(Lys) function and protein levels in Saccharomyces cerevisiae.

PubMed

Klassen, Roland; Grunewald, Pia; Thüring, Kathrin L; Eichler, Christian; Helm, Mark; Schaffrath, Raffael

2015-01-01

In eukaryotes, wobble uridines in the anticodons of tRNA(Lys)UUU, tRNA(Glu)UUC and tRNA(Gln)UUG are modified to 5-methoxy-carbonyl-methyl-2-thio-uridine (mcm5s2U). While mutations in subunits of the Elongator complex (Elp1-Elp6), which disable mcm5 side chain formation, or removal of components of the thiolation pathway (Ncs2/Ncs6, Urm1, Uba4) are individually tolerated, the combination of both modification defects has been reported to have lethal effects on Saccharomyces cerevisiae. Contrary to such absolute requirement of mcm5s2U for viability, we demonstrate here that in the S. cerevisiae S288C-derived background, both pathways can be simultaneously inactivated, resulting in combined loss of tRNA anticodon modifications (mcm5U and s2U) without a lethal effect. However, an elp3 disruption strain displays synthetic sick interaction and synergistic temperature sensitivity when combined with either uba4 or urm1 mutations, suggesting major translational defects in the absence of mcm5s2U modifications. Consistent with this notion, we find cellular protein levels drastically decreased in an elp3uba4 double mutant and show that this effect as well as growth phenotypes can be partially rescued by excess of tRNA(Lys)UUU. These results may indicate a global translational or protein homeostasis defect in cells simultaneously lacking mcm5 and s2 wobble uridine modification that could account for growth impairment and mainly originates from tRNA(Lys)UUU hypomodification and malfunction.

Sequential steps in DNA replication are inhibited to ensure reduction of ploidy in meiosis

PubMed Central

Hua, Hui; Namdar, Mandana; Ganier, Olivier; Gregan, Juraj; Méchali, Marcel; Kearsey, Stephen E.

2013-01-01

Meiosis involves two successive rounds of chromosome segregation without an intervening S phase. Exit from meiosis I is distinct from mitotic exit, in that replication origins are not licensed by Mcm2-7 chromatin binding, but spindle disassembly occurs during a transient interphase-like state before meiosis II. The absence of licensing is assumed to explain the block to DNA replication, but this has not been formally tested. Here we attempt to subvert this block by expressing the licensing control factors Cdc18 and Cdt1 during the interval between meiotic nuclear divisions. Surprisingly, this leads only to a partial round of DNA replication, even when these factors are overexpressed and effect clear Mcm2-7 chromatin binding. Combining Cdc18 and Cdt1 expression with modulation of cyclin-dependent kinase activity, activation of Dbf4-dependent kinase, or deletion of the Spd1 inhibitor of ribonucleotide reductase has little additional effect on the extent of DNA replication. Single-molecule analysis indicates this partial round of replication results from inefficient progression of replication forks, and thus both initiation and elongation replication steps may be inhibited in late meiosis. In addition, DNA replication or damage during the meiosis I–II interval fails to arrest meiotic progress, suggesting absence of checkpoint regulation of meiosis II entry. PMID:23303250

Spacewire on Earth orbiting scatterometers

NASA Technical Reports Server (NTRS)

Bachmann, Alex; Lang, Minh; Lux, James; Steffke, Richard

2002-01-01

The need for a high speed, reliable and easy to implement communication link has led to the development of a space flight oriented version of IEEE 1355 called SpaceWire. SpaceWire is based on high-speed (200 Mbps) serial point-to-point links using Low Voltage Differential Signaling (LVDS). SpaceWIre has provisions for routing messages between a large network of processors, using wormhole routing for low overhead and latency. {additionally, there are available space qualified hybrids, which provide the Link layer to the user's bus}. A test bed of multiple digital signal processor breadboards, demonstrating the ability to meet signal processing requirements for an orbiting scatterometer has been implemented using three Astrium MCM-DSPs, each breadboard consists of a Multi Chip Module (MCM) that combines a space qualified Digital Signal Processor and peripherals, including IEEE-1355 links. With the addition of appropriate physical layer interfaces and software on the DSP, the SpaceWire link is used to communicate between processors on the test bed, e.g. sending timing references, commands, status, and science data among the processors. Results are presented on development issues surrounding the use of SpaceWire in this environment, from physical layer implementation (cables, connectors, LVDS drivers) to diagnostic tools, driver firmware, and development methodology. The tools, methods, and hardware, software challenges and preliminary performance are investigated and discussed.

o-Vanillin functionalized mesoporous silica - coated magnetite nanoparticles for efficient removal of Pb(II) from water

NASA Astrophysics Data System (ADS)

Culita, Daniela C.; Simonescu, Claudia Maria; Patescu, Rodica-Elena; Dragne, Mioara; Stanica, Nicolae; Oprea, Ovidiu

2016-06-01

o-Vanillin functionalized mesoporous silica - coated magnetite (Fe3O4@MCM-41-N-oVan) was synthesized and fully characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, N2 adsorption-desorption technique and magnetic measurements. The capacity of Fe3O4@MCM-41-N-oVan to adsorb Pb(II) from aqueous solutions was evaluated in comparison with raw mesoporous silica - coated magnetite (Fe3O4@MCM-41) and amino - modified mesoporous silica coated magnetite (Fe3O4@MCM-41-NH2). The effect of adsorption process parameters such us pH, contact time, initial Pb(II) concentration was also investigated. The adsorption data were successfully fitted with the Langmuir model, exhibiting a maximum adsorption capacity of 155.71 mg/g at pH=4.4 and T=298 K. The results revealed that the adsorption rate was very high at the beginning of the adsorption process, 80-90% of the total amount of Pb(II) being removed within the first 60 min, depending on the initial concentration. The results of the present work suggest that Fe3O4@MCM-41-N-oVan is a suitable candidate for the separation of Pb(II) from contaminated water.

Magnetic α-Fe2O3/MCM-41 nanocomposites: preparation, characterization, and catalytic activity for methylene blue degradation.

PubMed

Ursachi, Irina; Stancu, Alexandru; Vasile, Aurelia

2012-07-01

Catalysts based on nanosized magnetic iron oxide stabilized inside the pore system of ordered mesoporous silica MCM-41 have been prepared. The obtained materials were characterized by powder X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and N(2) adsorption-desorption isotherm. XRD analysis showed that the obtained materials consist from the pure hematite crystalline phase (α-Fe(2)O(3)) dispersed within ordered mesoporous silica MCM-41. Magnetic measurements show that the obtained nanocomposites exhibit at room temperature weak ferromagnetic behavior with slender hysteresis. The catalytic activity of the magnetic α-Fe(2)O(3)/MCM-41 nanocomposites was evaluated by the degradation of methylene blue (MB) aqueous solution. For this purpose, an ultrasound-assisted Fenton-like process was used. The effect of solution pH on degradation of MB was investigated. The results indicated that US-H(2)O(2)-α-Fe(2)O(3)/MCM-41 nanocomposite system is effective for the degradation of MB, suggesting its great potential in removal of dyes from wastewater. It was found that the degradation rate of MB increases with decrease in the pH value of the solution. Copyright © 2012 Elsevier Inc. All rights reserved.

The effects of ageing time on the microstructure and properties of mesoporous silica-hydroxyapatite nanocomposite

NASA Astrophysics Data System (ADS)

Yousefpour, Mardali; Taherian, Zahra

2013-02-01

In this study, a mesoporous silica-hydroxyapatite nanocomposite (MCM-41/HA) was synthesized via sol-gel technique as a drug delivery system. The synthesis of MCM-41/hydroxyapatite nanocomposite was carried out at room temperature. The effect of various ageing time on the nanocomposite properties was studied during synthesis process. 0, 24, 36, and 48 h aging times were chosen. Textural properties and microstructure of the nanocomposites were characterized by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectroscopy (EDS), Electron Diffraction pattern (ED), and N2 adsorption-desorption. Results showed that ageing process led to HA crystals nucleation and growth on the surface of mesoporous silica. At 48 h of aging time, the surface area and total pore volume increased from 36.2 to 334 m2/g and 0.14-0.7 cm3/g, respectively. In contrast, the average pore diameter considerably decreased from 20.1 nm for (MCM-41/HA)24 to 8.39 nm for (MCM-41/HA)48. Furthermore, it was observed more homogeneous pore distribution with increasing the ageing time. In conclusion, the ageing time play an important role on textural properties of MCM-41/HA nanocomposite which could have a major effect on drug delivery properties such as molecular loading and release kinetics.

Response of Fibroblasts MRC-5 to Flufenamic Acid-Grafted MCM-41 Nanoparticles.

PubMed

Lara, Giovanna Gomes; Cipreste, Marcelo Fernandes; Andrade, Gracielle Ferreira; Silva, Wellington Marcos da; Sousa, Edésia Martins Barros de

2018-01-09

Recently, flufenamic acid (FFA) was discovered among fenamates as a free radical scavenger and gap junction blocker; however, its effects have only been studied in cancer cells. Normal cells in the surroundings of a tumor also respond to radiation, although they are not hit by it directly. This phenomenon is known as the bystander effect, where response molecules pass from tumor cells to normal ones, through communication channels called gap junctions. The use of the enhanced permeability and retention effect, through which drug-loaded nanoparticles smaller than 200 nm may accumulate around a tumor, can prevent the local side effect upon controlled release of the drug. The present work, aimed at functionalizing MCM-41 (Mobil Composition of Matter No. 41) silica nanoparticles with FFA and determining its biocompatibility with human fibroblasts MRC-5 (Medical Research Council cell strain 5). MCM-41, was synthesized and characterized structurally and chemically, with multiple techniques. The biocompatibility assay was performed by Live/Dead technique, with calcein and propidium-iodide. MRC-5 cells were treated with FFA-grafted MCM-41 for 48 h, and 98% of cells remained viable, without signs of necrosis or morphological changes. The results show the feasibility of MCM-41 functionalization with FFA, and its potential protection of normal cells, in comparison to the role of FFA in cancerous ones.

A Clean, Mild, and Efficient Preparation of Aryl 14H-benzo[a,j]xanthene leuco-dye Derivatives Via Nanocatalytic MCM-41-SO3H Under Ultrasonic Irradiation in Aqueous Media.

PubMed

Fathollahi, Mostafa; Rostamizadeh, Shahnaz; Amani, Ali M

2018-01-01

The present study has developed an efficient and eco-friendly protocol for the synthesis of aryl-14-H-dibenzo[a,j] xanthenes through a one-pot condensation reaction of 2-naphthol and arylaldehydes in aqueous media using the nanocatalytic MCM-41-SO3H under ultrasonic illumination. Using SEM and XRD analyses, MCM-41-SO3H nanoparticles were characterized. Therefore, for high magnification, taking the SEM image, the mesoporous surface of MCM-41-SO3H nanoparticles coated with gold for 2 minutes was characterized. Moreover, at a scan rate of 0.02° (2θ)/sec, XRD analysis from 1.5° (2θ) to 10.0° (2θ) was performed. For our considered sample, some well-ordered XRD patterns with one main peak as well as three minor peaks equal to those of MCM-41 materials were observed. The suggested route demonstrates very promising properties like higher yields, decrease in the time of reaction (5-10 min), mild and straightforward conditions, low level of toxicity, and inclusion of a cost-efficient and ecofriendly catalyst having considerable reusability. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

A Thin Film Nanocomposite Membrane with MCM-41 Silica Nanoparticles for Brackish Water Purification.

PubMed

Kadhom, Mohammed; Yin, Jun; Deng, Baolin

2016-12-06

Thin film nanocomposite (TFN) membranes containing MCM-41 silica nanoparticles (NPs) were synthesized by the interfacial polymerization (IP) process. An m -phenylenediamine (MPD) aqueous solution and an organic phase with trimesoyl chloride (TMC) dissolved in isooctane were used in the IP reaction, occurring on a nanoporous polysulfone (PSU) support layer. Isooctane was introduced as the organic solvent for TMC in this work due to its intermediate boiling point. MCM-41 silica NPs were loaded in MPD and TMC solutions in separate experiments, in a concentration range from 0 to 0.04 wt %, and the membrane performance was assessed and compared based on salt rejection and water flux. The prepared membranes were characterized via scanning electron microscopy (SEM), transmission electron microscopy (TEM), contact angle measurement, and attenuated total reflection Fourier transform infrared (ATR FT-IR) analysis. The results show that adding MCM-41 silica NPs into an MPD solution yields slightly improved and more stable results than adding them to a TMC solution. With 0.02% MCM-41 silica NPs in the MPD solution, the water flux was increased from 44.0 to 64.1 L/m²·h, while the rejection virtually remained the same at 95% (2000 ppm NaCl saline solution, 25 °C, 2068 kPa (300 psi)).

Removal of tetracycline from aqueous solution by MCM-41-zeolite A loaded nano zero valent iron: Synthesis, characteristic, adsorption performance and mechanism.

PubMed

Guo, Yige; Huang, Wenli; Chen, Bin; Zhao, Ying; Liu, Dongfang; Sun, Yu; Gong, Bin

2017-10-05

In this study, nano zero valent iron (NZVI) modified MCM-41-zeolite A (Fe-MCM-41-A) composite as a novel adsorbent was prepared by precipitation method and applied for tetracycline (TC) removal from aqueous solution. The adsorbent was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and N 2 -BET analysis. Hysteresis loops indicated that the sample has a desirable magnetic property and can be separated quickly. Adsorption studies were carried out to evaluate its potential for TC removal. Results showed that the optimal Fe-MCM-41-A dosage, initial pH and reaction time at initial TC concentration of 100mgL -1 solution are 1gL -1 , pH=5, and 60 min respectively, at which the removal efficiency of TC was 98.7%. The TC adsorption results fitted the Langmuir isotherm model very well and the adsorption process could be described by a pseudo-second-order kinetic model. A maximum TC adsorption capacity of 526.32mgg -1 was achieved. This study demonstrates that Fe-MCM-41-A is a promising and efficient material for TC adsorption from aqueous solution. Copyright © 2017 Elsevier B.V. All rights reserved.

Method of conditional moments (MCM) for the Chemical Master Equation: a unified framework for the method of moments and hybrid stochastic-deterministic models.

PubMed

Hasenauer, J; Wolf, V; Kazeroonian, A; Theis, F J

2014-09-01

The time-evolution of continuous-time discrete-state biochemical processes is governed by the Chemical Master Equation (CME), which describes the probability of the molecular counts of each chemical species. As the corresponding number of discrete states is, for most processes, large, a direct numerical simulation of the CME is in general infeasible. In this paper we introduce the method of conditional moments (MCM), a novel approximation method for the solution of the CME. The MCM employs a discrete stochastic description for low-copy number species and a moment-based description for medium/high-copy number species. The moments of the medium/high-copy number species are conditioned on the state of the low abundance species, which allows us to capture complex correlation structures arising, e.g., for multi-attractor and oscillatory systems. We prove that the MCM provides a generalization of previous approximations of the CME based on hybrid modeling and moment-based methods. Furthermore, it improves upon these existing methods, as we illustrate using a model for the dynamics of stochastic single-gene expression. This application example shows that due to the more general structure, the MCM allows for the approximation of multi-modal distributions.

Neuromorphic VLSI Models of Selective Attention: From Single Chip Vision Sensors to Multi-chip Systems

PubMed Central

Indiveri, Giacomo

2008-01-01

Biological organisms perform complex selective attention operations continuously and effortlessly. These operations allow them to quickly determine the motor actions to take in response to combinations of external stimuli and internal states, and to pay attention to subsets of sensory inputs suppressing non salient ones. Selective attention strategies are extremely effective in both natural and artificial systems which have to cope with large amounts of input data and have limited computational resources. One of the main computational primitives used to perform these selection operations is the Winner-Take-All (WTA) network. These types of networks are formed by arrays of coupled computational nodes that selectively amplify the strongest input signals, and suppress the weaker ones. Neuromorphic circuits are an optimal medium for constructing WTA networks and for implementing efficient hardware models of selective attention systems. In this paper we present an overview of selective attention systems based on neuromorphic WTA circuits ranging from single-chip vision sensors for selecting and tracking the position of salient features, to multi-chip systems implement saliency-map based models of selective attention. PMID:27873818

Neuromorphic VLSI Models of Selective Attention: From Single Chip Vision Sensors to Multi-chip Systems.

PubMed

Indiveri, Giacomo

2008-09-03

Biological organisms perform complex selective attention operations continuously and effortlessly. These operations allow them to quickly determine the motor actions to take in response to combinations of external stimuli and internal states, and to pay attention to subsets of sensory inputs suppressing non salient ones. Selective attention strategies are extremely effective in both natural and artificial systems which have to cope with large amounts of input data and have limited computational resources. One of the main computational primitives used to perform these selection operations is the Winner-Take-All (WTA) network. These types of networks are formed by arrays of coupled computational nodes that selectively amplify the strongest input signals, and suppress the weaker ones. Neuromorphic circuits are an optimal medium for constructing WTA networks and for implementing efficient hardware models of selective attention systems. In this paper we present an overview of selective attention systems based on neuromorphic WTA circuits ranging from single-chip vision sensors for selecting and tracking the position of salient features, to multi-chip systems implement saliency-map based models of selective attention.

DNA Interactions Probed by Hydrogen-Deuterium Exchange (HDX) Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Confirm External Binding Sites on the Minichromosomal Maintenance (MCM) Helicase.

PubMed

Graham, Brian W; Tao, Yeqing; Dodge, Katie L; Thaxton, Carly T; Olaso, Danae; Young, Nicolas L; Marshall, Alan G; Trakselis, Michael A

2016-06-10

The archaeal minichromosomal maintenance (MCM) helicase from Sulfolobus solfataricus (SsoMCM) is a model for understanding structural and mechanistic aspects of DNA unwinding. Although interactions of the encircled DNA strand within the central channel provide an accepted mode for translocation, interactions with the excluded strand on the exterior surface have mostly been ignored with regard to DNA unwinding. We have previously proposed an extension of the traditional steric exclusion model of unwinding to also include significant contributions with the excluded strand during unwinding, termed steric exclusion and wrapping (SEW). The SEW model hypothesizes that the displaced single strand tracks along paths on the exterior surface of hexameric helicases to protect single-stranded DNA (ssDNA) and stabilize the complex in a forward unwinding mode. Using hydrogen/deuterium exchange monitored by Fourier transform ion cyclotron resonance MS, we have probed the binding sites for ssDNA, using multiple substrates targeting both the encircled and excluded strand interactions. In each experiment, we have obtained >98.7% sequence coverage of SsoMCM from >650 peptides (5-30 residues in length) and are able to identify interacting residues on both the interior and exterior of SsoMCM. Based on identified contacts, positively charged residues within the external waist region were mutated and shown to generally lower DNA unwinding without negatively affecting the ATP hydrolysis. The combined data globally identify binding sites for ssDNA during SsoMCM unwinding as well as validating the importance of the SEW model for hexameric helicase unwinding. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

The correlation of adsorption behavior between ciprofloxacin hydrochloride and the active sites of Fe-doped MCM-41

NASA Astrophysics Data System (ADS)

Wu, Ying; Tang, Yiming; Li, Laisheng; Liu, Peihong; Li, Xukai; Chen, Weirui; Xue, Ying

2018-02-01

Fe-MCM-41s with various molar ratios of silicon to iron (20, 40, 80 and 160) were prepared to investigate adsorption properties of ciprofloxacin hydrochloride (CPX) in aqueous solutions. Fe-MCM-41s were characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption/desorption isotherms and infrared spectroscopy (FT-IR). Effects of silicon–iron ratio, adsorbent dosage, pH and temperature were conducted to explore the adsorption mechanism of CPX on Fe-MCM-41. The results showed that the introduction of iron facilitated the absorption quantity for CPX from 20.04 to 83.33 mg g-1 at 120 min of reaction time, which was mainly attributed to surface complexation. The promotion of hydrophobic effect, electrostatic interactions and π-π electron donor–acceptor interaction also played coordinate roles in the adsorption process. The experimental kinetic data followed both the pseudo-second-order and intra-particle diffusion models, while the adsorption isotherm data fit well to Freundlich model at high temperature. Thermodynamic study showed that the adsorption was spontaneous. Under the effect of electrostatic interaction, pH of the solution strongly affected CPX adsorption. Five representative metal cations (Ca, Cu, Ni, Pb and Cd) were chosen to study the effects on CPX adsorption and their complexation. The inhibiting effect of metal cations on CPX adsorption was sequenced in the order of Cu > Ni > Pb > Cd > Ca, which followed the same order as the complexation stability constants between CPX and cations. The Fe-MCM-41 adsorbent possessed excellent reusability for 4 cycles use, suggesting a potential applicability of Fe-MCM-41 to remove CPX in water.

Immunohistochemical estimation of cell cycle phase in laryngeal neoplasia

PubMed Central

Chatrath, P; Scott, I S; Morris, L S; Davies, R J; Bird, K; Vowler, S L; Coleman, N

2006-01-01

We previously developed an immunohistochemical method for estimating cell cycle state and phase in tissue samples, including biopsies that are too small for flow cytometry. We have used our technique to examine whether primary abnormalities of the cell cycle exist in laryngeal neoplasia. Antibodies against the markers of cell cycle entry, minichromosome maintenance protein-2 (Mcm-2) and Ki67, and putative markers of cell cycle phase, cyclin D1 (G1-phase), cyclin A (S-phase), cyclin B1 (G2-phase) and phosphohistone H3 (Mitosis) were applied to paraffin-embedded sections of normal larynx (n=8), laryngeal dysplasia (n=10) and laryngeal squamous cell carcinoma (n=10). Cells expressing each marker were determined as a percentage of total cells, termed the labelling index (LI), and as a percentage of Mcm-2-positive cells, termed the labelling fraction (LF). The frequency of coexpression of each putative phase marker was investigated by confocal microscopy. There was a correlation between Mcm-2 and Ki67 LIs (ρ=0.93) but Mcm-2 LIs were consistently higher. All cells expressing a phase marker coexpressed Mcm-2, whereas Ki67 was not expressed in a proportion of these cells. The putative phase markers showed little coexpression. Labelling index values increased on progression from normal larynx through laryngeal dysplasia to squamous cell carcinoma for Mcm-2 (P=0.001), Ki67 (P=0.0002), cyclin D1 (P=0.015), cyclin A (P=0.0001) and cyclin B1 (P=0.0004). There was no evidence of an increase in the LF for any phase marker. Immunohistochemistry can be used to estimate cell cycle state and phase in laryngeal biopsies. Our data argues against primary cell cycle phase abnormalities in laryngeal neoplasia. PMID:16832409

Host cell interactome of PA protein of H5N1 influenza A virus in chicken cells.

PubMed

Wang, Qiao; Li, Qinghe; Liu, Ranran; Zheng, Maiqing; Wen, Jie; Zhao, Guiping

2016-03-16

Influenza A virus (IAV) heavily depends on viral-host protein interactions in order to replicate and spread. Identification of host factors that interact with viral proteins plays crucial roles in understanding the mechanism of IAV infection. Here we report the interaction landscape of H5N1 IAV PA protein in chicken cells through the use of affinity purification and mass spectrometry. PA protein was expressed in chicken cells and PA interacting complexes were captured by co-immunoprecipitation and analyzed by mass spectrometry. A total of 134 proteins were identified as PA-host interacting factors. Protein complexes including the minichromosome maintenance complex (MCM), 26S proteasome and the coat protein I (COPI) complex associated with PA in chicken cells, indicating the essential roles of these functional protein complexes during the course of IAV infection. Gene Ontology and pathway enrichment analysis both showed strong enrichment of PA interacting proteins in the category of DNA replication, covering genes such as PCNA, MCM2, MCM3, MCM4, MCM5 and MCM7. This study has uncovered the comprehensive interactome of H5N1 IAV PA protein in its chicken host and helps to establish the foundation for further investigation into the newly identified viral-host interactions. Influenza A virus (IAV) is a great threat to public health and avian production. However, the manner in which avian IAV recruits the host cellular machinery for replication and how the host antagonizes the IAV infection was previously poorly understood. Here we present the viral-host interactome of the H5N1 IAV PA protein and reveal the comprehensive association of host factors with PA. Copyright © 2016 Elsevier B.V. All rights reserved.

Transient Macroscopic Chemistry in the DSMC Method

NASA Astrophysics Data System (ADS)

Goldsworthy, M. J.; Macrossan, M. N.; Abdel-Jawad, M.

2008-12-01

In the Direct Simulation Monte Carlo method, a combination of statistical and deterministic procedures applied to a finite number of `simulator' particles are used to model rarefied gas-kinetic processes. Traditionally, chemical reactions are modelled using information from specific colliding particle pairs. In the Macroscopic Chemistry Method (MCM), the reactions are decoupled from the specific particle pairs selected for collisions. Information from all of the particles within a cell is used to determine a reaction rate coefficient for that cell. MCM has previously been applied to steady flow DSMC simulations. Here we show how MCM can be used to model chemical kinetics in DSMC simulations of unsteady flow. Results are compared with a collision-based chemistry procedure for two binary reactions in a 1-D unsteady shock-expansion tube simulation and during the unsteady development of 2-D flow through a cavity. For the shock tube simulation, close agreement is demonstrated between the two methods for instantaneous, ensemble-averaged profiles of temperature and species mole fractions. For the cavity flow, a high degree of thermal non-equilibrium is present and non-equilibrium reaction rate correction factors are employed in MCM. Very close agreement is demonstrated for ensemble averaged mole fraction contours predicted by the particle and macroscopic methods at three different flow-times. A comparison of the accumulated number of net reactions per cell shows that both methods compute identical numbers of reaction events. For the 2-D flow, MCM required similar CPU and memory resources to the particle chemistry method. The Macroscopic Chemistry Method is applicable to any general DSMC code using any viscosity or non-reacting collision models and any non-reacting energy exchange models. MCM can be used to implement any reaction rate formulations, whether these be from experimental or theoretical studies.

Evaluation of isoprene degradation in the detailed tropospheric chemical mechanism, MCM v3, using environmental chamber data

NASA Astrophysics Data System (ADS)

Pinho, P. G.; Pio, C. A.; Jenkin, M. E.

The isoprene degradation mechanism included in version 3 of the Master Chemical Mechanism (MCM v3) has been evaluated and refined, using the Statewide Air Pollution Research Center (SAPRC) environmental chamber datasets on the photo-oxidation of isoprene and its degradation products, methacrolein (MACR) and methylvinyl ketone (MVK). Prior to this, the MCM v3 butane degradation chemistry was also evaluated using chamber data on the photo-oxidation of butane, and its degradation products, methylethyl ketone (MEK), acetaldehyde (CH 3CHO) and formaldehyde (HCHO), in conjunction with an initial evaluation of the chamber-dependent auxiliary mechanisms for the series of relevant chambers. The MCM v3 mechanisms for both isoprene and butane generally performed well and were found to provide an acceptable reaction framework for describing the NO x-photo-oxidation experiments on the above systems, although a number of parameter modifications and refinements were identified which resulted in an improved performance. All these relate to the magnitude of sources of free radicals from organic chemical process, such as carbonyl photolysis rates and the yields of radicals from the reactions of O 3 with unsaturated oxygenates, and specific recommendations are made for refinements. In addition to this, it was necessary to include a representation of the reactions of O( 3P) with isoprene, MACR and MVK (which were not previously treated in MCM v3), and conclusions are drawn concerning the required extent of free radical formation from these reactions. Throughout the study, the performance of MCM v3 was also compared with that of the SAPRC-99 mechanism, which was developed and optimized in conjunction with the chamber datasets.

A potential bioactive wound dressing based on carboxymethyl cellulose/ZnO impregnated MCM-41 nanocomposite hydrogel.

PubMed

Rakhshaei, Rasul; Namazi, Hassan

2017-04-01

Lack of antibacterial activity, deficient water vapor and oxygen permeability, and insufficient mechanical properties are disadvantages of existing wound dressings. Hydrogels could absorb wound exudates due to their strong swelling ratio and give a cooling sensation and a wet environment. To overcome these shortcomings, flexible nanocomposite hydrogel films was prepared through combination of zinc oxide impregnated mesoporous silica (ZnO-MCM-41) as a nano drug carrier with carboxymethyl cellulose (CMC) hydrogel. Citric acid was used as cross linker to avoid the cytotoxicity of conventional cross linkers. The prepared nanocomposite hydrogel was characterized using X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Zeta potential and UV-vis spectroscopy. Results of swelling and erosion tests showed CMC/ZnO nanocomposite hydrogel disintegrated during the first hours of the test. Using MCM-41 as a substrate for ZnO nanoparticles solved this problem and the CMC/ZnO-MCM-41 showed a great improvement in tensile strength (12%), swelling (100%), erosion (53%) and gas permeability (500%) properties. Drug delivery and antibacterial properties of the nanocomposite hydrogel films studied using tetracycline (TC) as a broad spectrum antibiotic and showed a sustained TC release. This could efficiently decrease bandage exchange. Cytocompatibility of the nanocomposite hydrogel films has been analyzed in adipose tissue-derived stem cells (ADSCs) and results showed cytocompatibility of CMC/ZnO-MCM-41. Based on these results the prepared CMC nanocomposite hydrogel containing ZnO impregnated MCM-41, could serve as a kind of promising wound dressing with sustained drug delivery properties. Copyright © 2016 Elsevier B.V. All rights reserved.

Catalytic copyrolysis of particle board and polypropylene over Al-MCM-48

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Hannah; Choi, Suek Ju; Kim, Ji Man

Highlights: • Al-MCM-48 was used for catalytic copyrolysis of particle board and polypropylene. • Catalytic produced mainly hydrocarbons. • The hydrocarbons produced were mainly in the diesel range. - Abstract: Particle board and polypropylene (PP) at a mixing ratio of 1:1 were copyrolyzed over two Al-MCM-48 catalysts with Si/Al ratios of 20 and 80. The catalyst characteristics were examined by measuring the Brunauer-Emmett-Teller surface area, temperature programmed desorption of ammonia, and X-ray diffraction. The main pyrolysis products of particle board were oxygenates, acids, and phenolics, whereas a large quantity of hydrocarbons within the diesel fuel range was produced from copyrolysismore » with polypropylene. The catalytic copyrolysis of particle board and PP over the Al-MCM-48 catalysts produced bio-oil with a much larger hydrocarbon content than that from the catalytic pyrolysis of particle board only. The hydrocarbons produced were mainly in the diesel range, highlighting the potential for the production of high-quality fuel.« less

One-pot synthesis of MWW zeolite nanosheets using a rationally designed organic structure-directing agent

DOE PAGES

Luo, Helen Y.; Michaelis, Vladimir K.; Hodges, Sydney; ...

2015-07-22

A new material MIT-1 comprised of delaminated MWW zeolite nanosheets is synthesized in one-pot using a rationally designed organic structure-directing agent (OSDA). The OSDA is comprised of a hydrophilic head segment that resembles the OSDA used to synthesize the zeolite precursor MCM22(P), a hydrophobic tail segment that resembles the swelling agent used to swell MCM22(P), and a di-quaternary ammonium linker that connects both segments. MIT-1 features high crystallinity and surface areas exceeding 500 m 2g -1, and can be synthesized over a wide synthesis window that includes Si/Al ratios ranging from 13 to 67. Characterization data reveal high mesoporosity andmore » acid strength with no detectable amorphous silica phases. In conclusion, compared to MCM-22 and MCM-56, MIT-1 shows a three-fold increase in catalytic activity for the Friedel-Crafts alkylation of benzene with benzyl alcohol.« less

MCM - 2 and Ki - 67 as proliferation markers in renal cell carcinoma: A quantitative and semi - quantitative analysis

PubMed Central

Mehdi, Muhammad Zain; Nagi, Abdul Hanan; Naseem, Nadia

2016-01-01

ABSTRACT Introduction/Background: Fuhrman nuclear grade is the most important histological parameter to predict prognosis in a patient of renal cell carcinoma (RCC). However, it suffers from inter-observer and intra-observer variation giving rise to need of a parameter that not only correlates with nuclear grade but is also objective and reproducible. Proliferation is the measure of aggressiveness of a tumour and it is strongly correlated with Fuhrman nuclear grade, clinical survival and recurrence in RCC. Ki-67 is conventionally used to assess proliferation. Mini-chromosome maintenance 2 (MCM-2) is a lesser known marker of proliferation and identifies a greater proliferation faction. This study was designed to assess the prognostic significance of MCM-2 by comparing it with Fuhrman nuclear grade and Ki-67. Material and Methods: n=50 cases of various ages, stages, histological subtypes and grades of RCC were selected for this study. Immunohistochemical staining using Ki-67(MIB-1, Mouse monoclonal antibody, Dako) and MCM-2 (Mouse monoclonal antibody, Thermo) was performed on the paraffin embedded blocks in the department of Morbid anatomy and Histopathology, University of Health Sciences, Lahore. Labeling indices (LI) were determined by two pathologists independently using quantitative and semi-quantitative analysis. Statistical analysis was carried out using SPSS 20.0. Kruskall-Wallis test was used to determine a correlation of proliferation markers with grade, and Pearson's correlate was used to determine correlation between the two proliferation markers. Results: Labeling index of MCM-2 (median=24.29%) was found to be much higher than Ki-67(median=13.05%). Both markers were significantly related with grade (p=0.00; Kruskall-Wallis test). LI of MCM-2 was found to correlate significantly with LI of Ki-67(r=0.0934;p=0.01 with Pearson's correlate). Results of semi-quantitative analysis correlated well with quantitative analysis. Conclusion: Both Ki-67 and MCM-2 are markers of proliferation which are closely linked to grade. Therefore, they can act as surrogate markers for grade in a manner that is more objective and reproducible. PMID:27532114

Malformation risk of antiepileptic drug exposure during pregnancy in women with epilepsy: Results from a pregnancy registry in South India.

PubMed

Thomas, Sanjeev V; Jose, Manna; Divakaran, Srividya; Sankara Sarma, Prabhakaran

2017-02-01

Kerala Registry of Epilepsy and Pregnancy had been prospectively evaluating the reproductive issues of women with epilepsy since April 1998. This analysis aimed to estimate the relative risk of major congenital malformations (MCM) to the registrants. All pregnancies with known outcome in this register until December 2013 were included. Malformation status was evaluated by antenatal ultrasonography, physical examination at birth, echocardiography, and abdomen ultrasonography at 3 months of age and a final review at 1 year of age. There were 1,688 fetuses (singlets 1,643, twins 21, and triplet 1) resulting in 1,622 live births. All were born to women of Asian origin living in South India. The MCM rate for all live births was 6.84% (95% confidence interval [CI] 5.71-8.18) and for all pregnancy outcomes including fetal loss was 7.11% (95% CI 5.98-8.44). The MCM rates (mean with 95% CI) for exposed group were 6.4% (5.03-8.03) for monotherapy and 9.9% (7.37-13.13) for polytherapy; internal control group (women with epilepsy [WWE] not on antiepileptic drugs [AEDs] in first trimester) 5.6% (3.34-9.11), external control group (women without epilepsy or AED exposure in first trimester) 3.45% (1.94-6.07). Valproate monotherapy group had a dose-dependent relative risk for MCM of 2.6 (95% CI 1.30-5.20) compared to the external control group. The preliminary data on MCM rate for the nine total clobazam monotherapy (22.2%; 95% CI 6.2-54.7) signals increased risk that needs further validation on larger sample size. There was no association between MCM rate and maternal socioeconomic status, epilepsy syndrome, or use of folic acid in first trimester. This dataset from South India confirms the increased risk of MCM with exposure to AEDs, particularly polytherapy. A dose-dependent increased risk was observed with valproate. The increased risk associated with clobazam monotherapy is an important signal that needs to be confirmed in a larger sample. Wiley Periodicals, Inc. © 2017 International League Against Epilepsy.

MCM - 2 and Ki - 67 as proliferation markers in renal cell carcinoma: A quantitative and semi - quantitative analysis.

PubMed

Mehdi, Muhammad Zain; Nagi, Abdul Hanan; Naseem, Nadia

2016-01-01

Fuhrman nuclear grade is the most important histological parameter to predict prognosis in a patient of renal cell carcinoma (RCC). However, it suffers from inter-observer and intra-observer variation giving rise to need of a parameter that not only correlates with nuclear grade but is also objective and reproducible. Proliferation is the measure of aggressiveness of a tumour and it is strongly correlated with Fuhrman nuclear grade, clinical survival and recurrence in RCC. Ki-67 is conventionally used to assess proliferation. Mini-chromosome maintenance 2 (MCM-2) is a lesser known marker of proliferation and identifies a greater proliferation faction. This study was designed to assess the prognostic significance of MCM-2 by comparing it with Fuhrman nuclear grade and Ki-67. n=50 cases of various ages, stages, histological subtypes and grades of RCC were selected for this study. Immunohistochemical staining using Ki-67(MIB-1, Mouse monoclonal antibody, Dako) and MCM-2 (Mouse monoclonal antibody, Thermo) was performed on the paraffin embedded blocks in the department of Morbid anatomy and Histopathology, University of Health Sciences, Lahore. Labeling indices (LI) were determined by two pathologists independently using quantitative and semi-quantitative analysis. Statistical analysis was carried out using SPSS 20.0. Kruskall-Wallis test was used to determine a correlation of proliferation markers with grade, and Pearson's correlate was used to determine correlation between the two proliferation markers. Labeling index of MCM-2 (median=24.29%) was found to be much higher than Ki-67(median=13.05%). Both markers were significantly related with grade (p=0.00; Kruskall-Wallis test). LI of MCM-2 was found to correlate significantly with LI of Ki-67(r=0.0934;p=0.01 with Pearson's correlate). Results of semi-quantitative analysis correlated well with quantitative analysis. Both Ki-67 and MCM-2 are markers of proliferation which are closely linked to grade. Therefore, they can act as surrogate markers for grade in a manner that is more objective and reproducible. Copyright® by the International Brazilian Journal of Urology.

Unconscious memory bias in depression: perceptual and conceptual processes.

PubMed

Watkins, P C; Martin, C K; Stern, L D

2000-05-01

Mood-congruent memory (MCM) bias in depression was investigated using 4 different implicit memory tests. Two of the implicit tests were perceptually driven, and 2 were conceptually driven. Depressed participants and nondepressed controls were assigned to 1 of 4 implicit memory tests after studying positive and negative adjectives. Results showed no MCM bias in the perceptually driven tests. MCM was demonstrated in 1 of the conceptually driven tests, but only for adjectives that were conceptually encoded. Results support the theory that mood-congruent processes in depression are limited to conceptual processing. However, activation of conceptual processes may not be sufficient for demonstrating mood congruency.

A high-sensitivity electrochemical immunosensor based on mobile crystalline material-41-polyvinyl alcohol nanocomposite and colloidal gold nanoparticles.

PubMed

Omidfar, Kobra; Zarei, Hajar; Gholizadeh, Fatemeh; Larijani, Bagher

2012-02-15

A novel competitive immunosensor was developed as a model system using anti-human serum albumin (HSA)-conjugated gold nanoparticles (AuNPs) as an electrochemical label and mobile crystalline material-41 (MCM-41)-polyvinyl alcohol (PVA) mesoporous nanocomposite as an immobilization platform. However, no attempt has yet been made to use the MCM-41 as the supporting electrolyte for the electrosynthesis of nonconducting polymer nanocomposite. This hybrid membrane was evaluated extensively by using field emission scanning electron microscopy (FESEM), cyclic voltammetry (CV), and differential pulse voltammetry (DPV) to determine its physicochemical and electrochemical properties in immunosensor application. FESEM revealed an appropriate and stable attachment between HSA and MCM-41 and also a dense layer deposition of MCM-41-HSA-PVA film onto the electrode surfaces. DPV was developed for quantitative determination of antigen in biological samples. A decrease in DPV responses was observed with increasing concentrations of HSA in standard and real samples. In optimal conditions, this immunosensor based on MCM-41-PVA nanocomposite film could detect HSA in a high linear range (0.5-200 μg ml⁻¹) with a low detection limit of 1 ng ml⁻¹. The proposed method showed acceptable reproducibility, stability, and reliability and could also be applied to detect the other antigens. Copyright © 2011 Elsevier Inc. All rights reserved.

Ubiquitin immobilized on mesoporous MCM41 silica surfaces - Analysis by solid-state NMR with biophysical and surface characterization.

PubMed

Adiram-Filiba, Nurit; Schremer, Avital; Ohaion, Eli; Nadav-Tsubery, Merav; Lublin-Tennenbaum, Tammi; Keinan-Adamsky, Keren; Goobes, Gil

2017-05-31

Deriving the conformation of adsorbed proteins is important in the assessment of their functional activity when immobilized. This has particularly important bearings on the design of contemporary and new encapsulated enzyme-based drugs, biosensors, and other bioanalytical devices. Solid-state nuclear magnetic resonance (NMR) measurements can expand our molecular view of proteins in this state and of the molecular interactions governing protein immobilization on popular biocompatible surfaces such as silica. Here, the authors study the immobilization of ubiquitin on the mesoporous silica MCM41 by NMR and other techniques. Protein molecules are shown to bind efficiently at pH 5 through electrostatic interactions to individual MCM41 particles, causing their agglutination. The strong attraction of ubiquitin to MCM41 surface is given molecular context through evidence of proximity of basic, carbonyl and polar groups on the protein to groups on the silica surface using NMR measurements. The immobilized protein exhibits broad peaks in two-dimensional 13 C dipolar-assisted rotational resonance spectra, an indication of structural multiplicity. At the same time, cross-peaks related to Tyr and Phe sidechains are missing due to motional averaging. Overall, the favorable adsorption of ubiquitin to MCM41 is accompanied by conformational heterogeneity and by a major loss of motional degrees of freedom as inferred from the marked entropy decrease. Nevertheless, local motions of the aromatic rings are retained in the immobilized state.

Controlled drug release on amine functionalized spherical MCM-41

DOE Office of Scientific and Technical Information (OSTI.GOV)

Szegedi, Agnes, E-mail: szegedi@chemres.hu; Popova, Margarita; Goshev, Ivan

2012-10-15

MCM-41 silica with spherical morphology and small particle sizes (100 nm) was synthesized and modified by post-synthesis method with different amounts of 3-aminopropyltriethoxysilane (APTES). A comparative study of the adsorption and release of a model drug, ibuprofen, was carried out. The modified and drug loaded mesoporous materials were characterized by XRD, TEM, N{sub 2} physisorption, elemental analysis, thermal analysis and FT-IR spectroscopy. A new method was developed for the quantitative determination of amino groups in surface modified mesoporous materials by the ninhydrin reaction. Good correlation was found between the amino content of the MCM-41 materials determined by the ninhydrin methodmore » and their ibuprofen adsorption capacity. Amino modification resulted in high degree of ibuprofen loading and slow release rate in comparison to the parent non-modified MCM-41. - Graphical abstract: Determination of surface amino groups by ninhidrin method. Highlights: Black-Right-Pointing-Pointer Spherical MCM-41 modified by different amounts of APTES was studied. Black-Right-Pointing-Pointer Ibuprofen (IBU) adsorption and release characteristics was tested. Black-Right-Pointing-Pointer The ninhydrin reaction was used for the quantitative determination of amino groups. Black-Right-Pointing-Pointer Stoichiometric amount of APTES is enough for totally covering the surface with amino groups. Black-Right-Pointing-Pointer Good correlation was found between the amino content and IBU adsorption capacity.« less

Rif1 controls DNA replication by directing Protein Phosphatase 1 to reverse Cdc7-mediated phosphorylation of the MCM complex.

PubMed

Hiraga, Shin-Ichiro; Alvino, Gina M; Chang, Fujung; Lian, Hui-Yong; Sridhar, Akila; Kubota, Takashi; Brewer, Bonita J; Weinreich, Michael; Raghuraman, M K; Donaldson, Anne D

2014-02-15

Initiation of eukaryotic DNA replication requires phosphorylation of the MCM complex by Dbf4-dependent kinase (DDK), composed of Cdc7 kinase and its activator, Dbf4. We report here that budding yeast Rif1 (Rap1-interacting factor 1) controls DNA replication genome-wide and describe how Rif1 opposes DDK function by directing Protein Phosphatase 1 (PP1)-mediated dephosphorylation of the MCM complex. Deleting RIF1 partially compensates for the limited DDK activity in a cdc7-1 mutant strain by allowing increased, premature phosphorylation of Mcm4. PP1 interaction motifs within the Rif1 N-terminal domain are critical for its repressive effect on replication. We confirm that Rif1 interacts with PP1 and that PP1 prevents premature Mcm4 phosphorylation. Remarkably, our results suggest that replication repression by Rif1 is itself also DDK-regulated through phosphorylation near the PP1-interacting motifs. Based on our findings, we propose that Rif1 is a novel PP1 substrate targeting subunit that counteracts DDK-mediated phosphorylation during replication. Fission yeast and mammalian Rif1 proteins have also been implicated in regulating DNA replication. Since PP1 interaction sites are evolutionarily conserved within the Rif1 sequence, it is likely that replication control by Rif1 through PP1 is a conserved mechanism.

Reduction of tobacco smoke components yield in commercial cigarette brands by addition of HUSY, NaY and Al-MCM-41 to the cigarette rod.

PubMed

Marcilla, A; Gómez-Siurana, A; Berenguer, D; Martínez-Castellanos, I; Beltrán, M I

2015-01-01

The effect of two zeolites, HUSY, NaY and a mesoporous synthesized Al-MCM-41 material on the smoke composition of ten commercial cigarettes brands has been studied. Cigarettes were prepared by mixing the tobacco with the three powdered materials, and the smoke obtained under the ISO conditions was analyzed. Up to 32 compounds were identified and quantified in the gas fraction and 80 in the total particulate matter (TPM) condensed in the cigarettes filters and in the traps located after the mouth end of the cigarettes. Al-MCM-41 is by far the best additive, providing the highest reductions of the yield for most compounds and brands analyzed. A positive correlation was observed among the TPM and nicotine yields with the reduction obtained in nicotine, CO, and most compounds with the three additives. The amount of ashes in additive free basis increases due to the coke deposited on the solids, especially with Al-MCM-41. Nicotine is reduced with Al-MCM-41 by an average of 34.4% for the brands studied (49.5% for the brand where the major reduction was obtained and 18.5 for the brand behaving the worst). CO is reduced by an average of 18.6% (ranging from 10.3 to 35.2% in the different brands).

Response of Fibroblasts MRC-5 to Flufenamic Acid-Grafted MCM-41 Nanoparticles

PubMed Central

Lara, Giovanna Gomes; Andrade, Gracielle Ferreira; da Silva, Wellington Marcos

2018-01-01

Recently, flufenamic acid (FFA) was discovered among fenamates as a free radical scavenger and gap junction blocker; however, its effects have only been studied in cancer cells. Normal cells in the surroundings of a tumor also respond to radiation, although they are not hit by it directly. This phenomenon is known as the bystander effect, where response molecules pass from tumor cells to normal ones, through communication channels called gap junctions. The use of the enhanced permeability and retention effect, through which drug-loaded nanoparticles smaller than 200 nm may accumulate around a tumor, can prevent the local side effect upon controlled release of the drug. The present work, aimed at functionalizing MCM-41 (Mobil Composition of Matter No. 41) silica nanoparticles with FFA and determining its biocompatibility with human fibroblasts MRC-5 (Medical Research Council cell strain 5). MCM-41, was synthesized and characterized structurally and chemically, with multiple techniques. The biocompatibility assay was performed by Live/Dead technique, with calcein and propidium–iodide. MRC-5 cells were treated with FFA-grafted MCM-41 for 48 h, and 98% of cells remained viable, without signs of necrosis or morphological changes. The results show the feasibility of MCM-41 functionalization with FFA, and its potential protection of normal cells, in comparison to the role of FFA in cancerous ones. PMID:29315235

Development of highly durable deep-ultraviolet AlGaN-based LED multichip array with hemispherical encapsulated structures using a selected resin through a detailed feasibility study

NASA Astrophysics Data System (ADS)

Nagai, Shoko; Yamada, Kiho; Hirano, Akira; Ippommatsu, Masamichi; Ito, Masahiro; Morishima, Naoki; Aosaki, Ko; Honda, Yoshio; Amano, Hiroshi; Akasaki, Isamu

2016-08-01

To replace mercury lamps with AlGaN-based deep-ultraviolet (DUV) LEDs, a simple and low-cost package with increased light extraction efficiency (LEE) is indispensable. Therefore, resin encapsulation is considered to be a key technology. However, the photochemical reactions induced by DUV light cause serious problems, and conventional resins cannot be used. In the former part of this study, a comparison of a silicone resin and fluorine polymers was carried out in terms of their suitability for encapsulation, and we concluded that only one of the fluorine polymers can be used for encapsulation. In the latter part, the endurance of encapsulation using the selected fluorine polymer was investigated, and we confirmed that the selected fluorine polymer can guarantee a lifetime of over 6,000 h at a wavelength of 265 nm. Furthermore, a 3 × 4 array module of encapsulated dies on a simple AlN submount was fabricated, demonstrating the possibility of W/cm2-class lighting.

Mood-Congruent Memory and Natural Mood: New Evidence.

ERIC Educational Resources Information Center

Mayer, John D.; And Others

1995-01-01

Presents new evidence that everyday mood does bring about a hypothesized effect on memory, termed mood-congruent memory (MCM). Results of three studies provided evidence for MCM among normal individuals (n=614). Findings support prior studies and bolster notions that mood and memory constantly covary in everyday experience. (RJM)

Development of Mesoporous Nanocatalysts for Production of Hydrogen and Fisher Tropsch Studies

NASA Astrophysics Data System (ADS)

Abrokwah, Richard Yeboah

The primary aim of this study was to develop mesoporous nanocatalysts for (i) hydrogen production via steam reforming of methanol (SRM) in a tubular reactor, and (ii) syngas conversion to hydrocarbons via Fisher-Tropsch synthesis using silicon microchannel microreactors. The mesoporous catalysts for SRM were prepared by an optimized one-pot hydrothermal synthesis procedure. The catalysts were investigated for SRM activity in a packed bed tubular reactor using metals, namely, Cu, Co, Ni, Pd, Zn, and Sn. The metals were incorporated in different supports -MCM-41, SBA-15, CeO2, TiO2, and ZrO2 to investigate the influence of support on catalyst properties. A sharp contrast in catalyst performance was noticed depending on the type of support employed. For example, in SRM at 250 °C, Cu supported on amorphous silica SBA-15 and MCM-41 produced significantly less CO (< 7%) compared to other crystalline supports Cu-TiO2 and Cu/ZrO2 that showed high CO selectivity of ˜56% and ˜37%, respectively. Amongst all the metals studied for SRM activity using 1:3 methanol:water mole ratio at 250 °C, 10%Cu-MCM-41 showed the best performance with 68% methanol conversion, 100% H2 , ˜6 % CO, 94% CO2 selectivities, and no methane formation. Furthermore, 10%Cu-CeO2 yielded the lowest CO selectivity of 1.84% and the highest CO2 selectivity of ˜98% at 250 °C. Stability studies of the catalysts conducted for time-on-stream of 40 h at 300 °C revealed that Cu-MCM41 was the most stable and displayed consistent steady state conversion of ˜74%. Our results indicate that, although coking played an influential role in deactivation of most catalysts, thermal sintering and changes in MCM-41 structure can be responsible for the catalyst deactivation. For monomtetallic systems, the MCM-41 supported catalysts especially Pd and Sn showed appreciable hydrothermal stability under the synthesis and reaction conditions. While bimetallic Pd-Co-MCM-41 and Cu-Ni-MCM-41 catalysts produced more CO, Cu-Zn-MCM-41 and Cu-Sn-MCM-41exhibited better SRM activity, and produced much less CO and CH4. In spite of the improved the stability and dispersion of the monometallic active sites in the support, no noticeable synergistic activity was observed in terms of H2 and CO selectivities in the multimetallic catalysts. For the Fisher-Tropsch (F-T) studies, Co-TiO 2, Fe-TiO2 and Ru-TiO2 catalysts were prepared by the sol-gel method and coated on 116 microchannels (50mum wide x 100mum deep) of a Si-microreactor. The F-T process parameters such as temperature, pressure and flow rates were controlled by an in-house setup programmed by LabVIEWRTM. The effect of temperature on F-T activity in the range of 150 to 300°C was investigated at 1 atm, a flow rate of 6 ml/min and a constant H2:CO molar ratio of 2:1. In our initial studies at 220 °C, 12%Ru-TiO2 showed higher CO conversion of 74% and produced the highest C2-C4 hydrocarbon selectivity-of ˜11% ethane, 22% propane and ˜17% butane. The overall catalyst stability and performance was in the order of 12%Ru-TiO2>> 12%Fe-TiO2 > 12%Co-TiO2.

Expression of peroxisome proliferator-activated receptors (PPARS) in human astrocytic cells: PPARgamma agonists as inducers of apoptosis.

PubMed

Chattopadhyay, N; Singh, D P; Heese, O; Godbole, M M; Sinohara, T; Black, P M; Brown, E M

2000-07-01

We report the isolation by RT-PCR of partial cDNAs encoding the human peroxisome proliferator-activated receptor (PPAR) isoforms PPARbeta and -gamma in human primary astrocytes (HPA) as well as in the human malignant astrocytoma cell line T98G. In contrast, we failed to detect PPARalpha mRNA in either of these two cell types. Because PPARbeta is ubiquitously expressed but has, as yet, no known function, we pursued our functional studies of these cells with regard to PPARgamma. To that end, we showed that PPARgamma protein is abundantly expressed in both cell types, having a molecular weight of approximately 50 kDa. Immunocytochemistry revealed a predominantly nuclear localization of this receptor. Moreover, incubation of the two cell types with 1-12 mcM 15-deoxy PGJ(2) or 1-12 mcM ciglitazone, both of which are agonists of PPARgamma, induced loss of cellular viability as assessed by the MTT assay after a 4 hr incubation. Reduced cellular viability as a consequence of exposure to PGJ(2) or ciglitazone resulted from induction of apoptosis, as assessed by DNA fragmentation and Hoechst staining, and involves activation of the CPP32 (caspase-3) protease. These data show that modulation of the process of apoptosis is one function of PPARgamma in cells derived from the human astrocytic lineage. Copyright 2000 Wiley-Liss, Inc.

78 FR 17996 - MCM Rail Services LLC-Petition for Retroactive Exemption-In Sparrows Point, Md.

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-25

... LLC--Petition for Retroactive Exemption--In Sparrows Point, Md. AGENCY: Surface Transportation Board... of rail line in Sparrows Point, Md. (the Line). DATES: MCM's supplemental information is due by April... Railroad, and currently named the Baltimore Industrial Railway, is located at 1430 Sparrows Point Boulevard...

DNA Replication Origins in Immunoglobulin Switch Regions Regulate Class Switch Recombination in an R-Loop-Dependent Manner.

PubMed

Wiedemann, Eva-Maria; Peycheva, Mihaela; Pavri, Rushad

2016-12-13

Class switch recombination (CSR) at the immunoglobulin heavy chain (IgH) locus generates antibody isotypes. CSR depends on double-strand breaks (DSBs) induced by activation-induced cytidine deaminase (AID). Although DSB formation and repair machineries are active in G1 phase, efficient CSR is dependent on cell proliferation and S phase entry; however, the underlying mechanisms are obscure. Here, we show that efficient CSR requires the replicative helicase, the Mcm complex. Mcm proteins are enriched at IgH switch regions during CSR, leading to assembly of facultative replication origins that require Mcm helicase function for productive CSR. Assembly of CSR-associated origins is facilitated by R loops and promotes the physical proximity (synapsis) of recombining switch regions, which is reduced by R loop inhibition or Mcm complex depletion. Thus, R loops contribute to replication origin specification that promotes DSB resolution in CSR. This suggests a mechanism for the dependence of CSR on S phase and cell division. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

RecQL4 is required for the association of Mcm10 and Ctf4 with replication origins in human cells

PubMed Central

Im, Jun-Sub; Park, Soon-Young; Cho, Won-Ho; Bae, Sung-Ho; Hurwitz, Jerard; Lee, Joon-Kyu

2015-01-01

Though RecQL4 was shown to be essential for the initiation of DNA replication in mammalian cells, its role in initiation is poorly understood. Here, we show that RecQL4 is required for the origin binding of Mcm10 and Ctf4, and their physical interactions and association with replication origins are controlled by the concerted action of both CDK and DDK activities. Although RecQL4-dependent binding of Mcm10 and Ctf4 to chromatin can occur in the absence of pre-replicative complex, their association with replication origins requires the presence of the pre-replicative complex and CDK and DDK activities. Their association with replication origins and physical interactions are also targets of the DNA damage checkpoint pathways which prevent initiation of DNA replication at replication origins. Taken together, the RecQL4-dependent association of Mcm10 and Ctf4 with replication origins appears to be the first important step controlled by S phase promoting kinases and checkpoint pathways for the initiation of DNA replication in human cells. PMID:25602958

Fast and efficient mesoporous adsorbents for the separation of toxic compounds from aqueous media.

PubMed

Anbia, Mansoor; Mohammadi, Nourali; Mohammadi, Kaveh

2010-04-15

The effect of cationic template on the adsorption of chromium (VI), furfural and copperphthalocyanine-3,4',4'',4'''-tetrasulfonic acid tetrasodium salt (CuPc) in MCM-41 and MCM-48 mesoporous materials was investigated in this work. We used cetyltrimethylammonium bromide (CTAB) as the cationic template and sodiummetasilicate (for MCM-41) and tetraethyl-orthosilicon (for MCM-48) as the silica source for the synthesis of mesoporous materials. The properties of synthesized samples were characterized with XRD-low angle, SEM, N(2) adsorption-desorption and TG-DT analysis. The extent of adsorption was investigated as a function of solution pH, shaking speed, contact time, analyte concentration, reaction temperature and supporting electrolyte (sodium chloride) concentration. Langmuir and Freundlich isotherms were used to model the adsorption equilibrium data. The as-synthesized mesoporous samples showed very high adsorption capacity for the analytes and adsorption uptakes were rapid on the adsorbents reaching equilibrium in less than 2 h. The materials without surfactant did not show significant affinity for the analytes. 2009 Elsevier B.V. All rights reserved.

Catalytic pyrolysis of oil fractions separated from food waste leachate over nanoporous acid catalysts.

PubMed

Kim, Seung-Soo; Heo, Hyeon Su; Kim, Sang Guk; Ryoo, Ryong; Kim, Jeongnam; Jeon, Jong-Ki; Park, Sung Hoon; Park, Young-Kwon

2011-07-01

Oil fractions, separated from food waste leachate, can be used as an energy source. Especially, high quality oil can be obtained by catalytic cracking. In this study, nanoporous catalysts such as Al-MCM-41 and mesoporous MFI type zeolite were applied to the catalytic cracking of oil fractions using the pyrolysis gas chromatography/mass spectrometry. Mesoporous MFI type zeolite showed better textural porosity than Al-MCM-41. In addition, mesoporous MFI type zeolite had strong Brönsted acidity while Al-MCM-41 had weak acidity. Significant amount of acid components in the food waste oil fractions were converted to mainly oxygenates and aromatics. As a result of its well-defined nanopores and strong acidity, the use of a mesoporous MFI type zeolite produced large amounts of gaseous and aromatic compounds. High yields of hydrocarbons within the gasoline range were also obtained in the case of mesoporous MFI type zeolite, whereas the use of Al-MCM-41, which exhibits relatively weak acidity, resulted in high yields of oxygenates and diesel range hydrocarbons.

Formation of (FexMn(2-x))O3 solid solution and high sulfur capacity properties of Mn-based/M41 sorbents for hot coal gas desulfurization.

PubMed

Zhang, Y; Liu, B S; Zhang, F M; Zhang, Z F

2013-03-15

Several MCM-41 materials were synthesized at different conditions by hydrothermal procedure using cheap and easily available industrial water glass as silica source. Fe doped manganese-based oxide/MCM-41 sorbents were prepared by a sol-gel method. The effects of loadings of metal oxide, Fe/Mn molar ratios over MCM-41 and reaction temperature on the performance of sorbent for hot coal gas desulfurization were investigated. Various techniques such as BET, XRD, XPS, LRS and HRTEM were used to characterize the sorbents. The result indicated Fe(3+) ions could occupy a position of Mn(3+) in cubic lattice of Mn2O3 and the (FexMn2-x)O3 solid solution is mainly active phase of sorbent. Moreover, the result of nine successive sulfurization-regeneration cycles of sorbent showed high sulfur adsorption capacity and endurable stability of FeMn4Ox/MCM-41 for H2S removal. Copyright © 2013 Elsevier B.V. All rights reserved.

Switch on the engine: how the eukaryotic replicative helicase MCM2-7 becomes activated.

PubMed

Tognetti, Silvia; Riera, Alberto; Speck, Christian

2015-03-01

A crucial step during eukaryotic initiation of DNA replication is the correct loading and activation of the replicative DNA helicase, which ensures that each replication origin fires only once. Unregulated DNA helicase loading and activation, as it occurs in cancer, can cause severe DNA damage and genomic instability. The essential mini-chromosome maintenance proteins 2-7 (MCM2-7) represent the core of the eukaryotic replicative helicase that is loaded at DNA replication origins during G1-phase of the cell cycle. The MCM2-7 helicase activity, however, is only triggered during S-phase once the holo-helicase Cdc45-MCM2-7-GINS (CMG) has been formed. A large number of factors and several kinases interact and contribute to CMG formation and helicase activation, though the exact mechanisms remain unclear. Crucially, upon DNA damage, this reaction is temporarily halted to ensure genome integrity. Here, we review the current understanding of helicase activation; we focus on protein interactions during CMG formation, discuss structural changes during helicase activation, and outline similarities and differences of the prokaryotic and eukaryotic helicase activation process.

Somatostatin Derivate (smsDX) Attenuates the TAM-Stimulated Proliferation, Migration and Invasion of Prostate Cancer via NF-κB Regulation.

PubMed

Guo, Zhaoxin; Xing, Zhaoquan; Cheng, Xiangyu; Fang, Zhiqing; Jiang, Chao; Su, Jing; Zhou, Zunlin; Xu, Zhonghua; Holmberg, Anders; Nilsson, Sten; Liu, Zhaoxu

2015-01-01

Tumor development and progression are influenced by macrophages of the surrounding microenvironment. To investigate the influences of an inflammatory tumor microenvironment on the growth and metastasis of prostate cancer, the present study used a co-culture model of prostate cancer (PCa) cells with tumor-associated macrophage (TAM)-conditioned medium (MCM). MCM promoted PCa cell (LNCaP, DU145 and PC-3) growth, and a xenograft model in nude mice consistently demonstrated that MCM could promote tumor growth. MCM also stimulated migration and invasion in vitro. Somatostatin derivate (smsDX) significantly attenuated the TAM-stimulated proliferation, migration and invasion of prostate cancer. Immunohistochemistry revealed that NF-κB was over-expressed in PCa and BPH with chronic inflammatory tissue specimens and was positively correlated with macrophage infiltration. Further investigation into the underlying mechanism revealed that NF-κB played an important role in macrophage infiltration. SmsDX inhibited the paracrine loop between TAM and PCa cells and may represent a potential therapeutic agent for PCa.

Associations of the MCM6-rs3754686 proxy for milk intake in Mediterranean and American populations with cardiovascular biomarkers, disease and mortality: Mendelian randomization.

PubMed

Smith, Caren E; Coltell, Oscar; Sorlí, Jose V; Estruch, Ramón; Martínez-González, Miguel Ángel; Salas-Salvadó, Jordi; Fitó, Montserrat; Arós, Fernando; Dashti, Hassan S; Lai, Chao Q; Miró, Leticia; Serra-Majem, Lluís; Gómez-Gracia, Enrique; Fiol, Miquel; Ros, Emilio; Aslibekyan, Stella; Hidalgo, Bertha; Neuhouser, Marian L; Di, Chongzhi; Tucker, Katherine L; Arnett, Donna K; Ordovás, José M; Corella, Dolores

2016-09-14

Controversy persists on the association between dairy products, especially milk, and cardiovascular diseases (CVD). Genetic proxies may improve dairy intake estimations, and clarify diet-disease relationships through Mendelian randomization. We meta-analytically (n ≤ 20,089) evaluated associations between a lactase persistence (LP) SNP, the minichromosome maintenance complex component 6 (MCM6)-rs3754686C>T (nonpersistence>persistence), dairy intake, and CVD biomarkers in American (Hispanics, African-American and Whites) and Mediterranean populations. Moreover, we analyzed longitudinal associations with milk, CVD and mortality in PREDIMED), a randomized Mediterranean diet (MedDiet) intervention trial (n = 7185). The MCM6-rs3754686/MCM6-rs309180 (as proxy), LP-allele (T) was strongly associated with higher milk intake, but inconsistently associated with glucose and lipids, and not associated with CVD or total mortality in the whole population. Heterogeneity analyses suggested some sex-specific associations. The T-allele was associated with higher CVD and mortality risk in women but not in men (P-sex interaction:0.005 and 0.032, respectively), mainly in the MedDiet group. However, milk intake was not associated with CVD biomarkers, CVD or mortality either generally or in sub-groups. Although MCM6-rs3754686 is a good milk intake proxy in these populations, attributing its associations with CVD and mortality in Mediterranean women to milk is unwarranted, as other factors limiting the assumption of causality in Mendelian randomization may exist.

The MADS-box transcription factor FgMcm1 regulates cell identity and fungal development in Fusarium graminearum.

PubMed

Yang, Cui; Liu, Huiquan; Li, Guotian; Liu, Meigang; Yun, Yingzi; Wang, Chenfang; Ma, Zhonghua; Xu, Jin-Rong

2015-08-01

In eukaryotic cells, MADS-box genes are known to play major regulatory roles in various biological processes by combinatorial interactions with other transcription factors. In this study, we functionally characterized the FgMCM1 MADS-box gene in Fusarium graminearum, the causal agent of wheat and barley head blight. Deletion of FgMCM1 resulted in the loss of perithecium production and phialide formation. The Fgmcm1 mutant was significantly reduced in virulence, deoxynivalenol biosynthesis and conidiation. In yeast two-hybrid assays, FgMcm1 interacted with Mat1-1-1 and Fst12, two transcription factors important for sexual reproduction. Whereas Fgmcm1 mutants were unstable and produced stunted subcultures, Fgmcm1 mat1-1-1 but not Fgmcm1 fst12 double mutants were stable. Furthermore, spontaneous suppressor mutations occurred frequently in stunted subcultures to recover growth rate. Ribonucleic acid sequencing analysis indicated that a number of sexual reproduction-related genes were upregulated in stunted subcultures compared with the Fgmcm1 mutant, which was downregulated in the expression of genes involved in pathogenesis, secondary metabolism and conidiation. We also showed that culture instability was not observed in the Fvmcm1 mutants of the heterothallic Fusarium verticillioides. Overall, our data indicate that FgMcm1 plays a critical role in the regulation of cell identity, sexual and asexual reproduction, secondary metabolism and pathogenesis in F. graminearum. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

Design of epoxy-functionalized Fe3O4@MCM-41 core-shell nanoparticles for enzyme immobilization.

PubMed

Ulu, Ahmet; Ozcan, Imren; Koytepe, Suleyman; Ates, Burhan

2018-05-01

The scope of our research was to prepare the organosilane-modified Fe 3 O 4 @MCM-41 core-shell magnetic nanoparticles, used for L-ASNase immobilization and explored screening of immobilization conditions such as pH, temperature, thermal stability, kinetic parameters, reusability and storage stability. In this content, Fe 3 O 4 core-shell magnetic nanoparticles were prepared via co-precipitation method and coated with MCM-41. Then, Fe 3 O 4 @MCM-41 magnetic nanoparticles were functionalized by (3-glycidyloxypropyl) trimethoxysilane (GPTMS) as an organosilane compound. Subsequently, L-ASNase was covalently immobilized on epoxy-functionalized Fe 3 O 4 @MCM-41 magnetic nanoparticles. The immobilized L-ASNase had greater activity at high pH and temperature values. It also maintained >92% of the initial activity after incubation at 55 °C for 3 h. Regarding kinetic values, immobilized L-ASNase showed a higher Vmax and lower Km compared to native L-ASNase. In addition, it displayed excellent reusability for 12 successive cycles. After 30 days of storage at 4 °C and 25 °C, immobilized L-ASNase retained 54% and 26% of its initial activities while native L-ASNase lost about 68% and 84% of its initial activity, respectively. As a result, the immobilization of L-ASNase onto magnetic nanoparticles may provide an advantage in terms of removal of L-ASNase from reaction media. Copyright © 2018. Published by Elsevier B.V.

Ultrastructural and Single-Cell-Level Characterization Reveals Metabolic Versatility in a Microbial Eukaryote Community from an Ice-Covered Antarctic Lake

PubMed Central

Li, Wei; Podar, Mircea

2016-01-01

ABSTRACT The McMurdo Dry Valleys (MCM) of southern Victoria Land, Antarctica, harbor numerous ice-covered bodies of water that provide year-round liquid water oases for isolated food webs dominated by the microbial loop. Single-cell microbial eukaryotes (protists) occupy major trophic positions within this truncated food web, ranging from primary producers (e.g., chlorophytes, haptophytes, and cryptophytes) to tertiary predators (e.g., ciliates, dinoflagellates, and choanoflagellates). To advance the understanding of MCM protist ecology and the roles of MCM protists in nutrient and energy cycling, we investigated potential metabolic strategies and microbial interactions of key MCM protists isolated from a well-described lake (Lake Bonney). Fluorescence-activated cell sorting (FACS) of enrichment cultures, combined with single amplified genome/amplicon sequencing and fluorescence microscopy, revealed that MCM protists possess diverse potential metabolic capabilities and interactions. Two metabolically distinct bacterial clades (Flavobacteria and Methylobacteriaceae) were independently associated with two key MCM lake microalgae (Isochrysis and Chlamydomonas, respectively). We also report on the discovery of two heterotrophic nanoflagellates belonging to the Stramenopila supergroup, one of which lives as a parasite of Chlamydomonas, a dominate primary producer in the shallow, nutrient-poor layers of the lake. IMPORTANCE Single-cell eukaryotes called protists play critical roles in the cycling of organic matter in aquatic environments. In the ice-covered lakes of Antarctica, protists play key roles in the aquatic food web, providing the majority of organic carbon to the rest of the food web (photosynthetic protists) and acting as the major consumers at the top of the food web (predatory protists). In this study, we utilized a combination of techniques (microscopy, cell sorting, and genomic analysis) to describe the trophic abilities of Antarctic lake protists and their potential interactions with other microbes. Our work reveals that Antarctic lake protists rely on metabolic versatility for their energy and nutrient requirements in this unique and isolated environment. PMID:27084010

Ultrastructural and Single-Cell-Level Characterization Reveals Metabolic Versatility in a Microbial Eukaryote Community from an Ice-Covered Antarctic Lake.

PubMed

Li, Wei; Podar, Mircea; Morgan-Kiss, Rachael M

2016-06-15

The McMurdo Dry Valleys (MCM) of southern Victoria Land, Antarctica, harbor numerous ice-covered bodies of water that provide year-round liquid water oases for isolated food webs dominated by the microbial loop. Single-cell microbial eukaryotes (protists) occupy major trophic positions within this truncated food web, ranging from primary producers (e.g., chlorophytes, haptophytes, and cryptophytes) to tertiary predators (e.g., ciliates, dinoflagellates, and choanoflagellates). To advance the understanding of MCM protist ecology and the roles of MCM protists in nutrient and energy cycling, we investigated potential metabolic strategies and microbial interactions of key MCM protists isolated from a well-described lake (Lake Bonney). Fluorescence-activated cell sorting (FACS) of enrichment cultures, combined with single amplified genome/amplicon sequencing and fluorescence microscopy, revealed that MCM protists possess diverse potential metabolic capabilities and interactions. Two metabolically distinct bacterial clades (Flavobacteria and Methylobacteriaceae) were independently associated with two key MCM lake microalgae (Isochrysis and Chlamydomonas, respectively). We also report on the discovery of two heterotrophic nanoflagellates belonging to the Stramenopila supergroup, one of which lives as a parasite of Chlamydomonas, a dominate primary producer in the shallow, nutrient-poor layers of the lake. Single-cell eukaryotes called protists play critical roles in the cycling of organic matter in aquatic environments. In the ice-covered lakes of Antarctica, protists play key roles in the aquatic food web, providing the majority of organic carbon to the rest of the food web (photosynthetic protists) and acting as the major consumers at the top of the food web (predatory protists). In this study, we utilized a combination of techniques (microscopy, cell sorting, and genomic analysis) to describe the trophic abilities of Antarctic lake protists and their potential interactions with other microbes. Our work reveals that Antarctic lake protists rely on metabolic versatility for their energy and nutrient requirements in this unique and isolated environment. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Ultrastructural and Single-Cell-Level Characterization Reveals Metabolic Versatility in a Microbial Eukaryote Community from an Ice-Covered Antarctic Lake

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Wei; Podar, Mircea; Morgan-Kiss, Rachael M.

The McMurdo Dry Valleys (MCM) of southern Victoria Land, Antarctica, harbor numerous ice-covered bodies of water that provide year-round liquid water oases for isolated food webs dominated by the microbial loop. Single-cell microbial eukaryotes (protists) occupy major trophic positions within this truncated food web, ranging from primary producers (e.g., chlorophytes, haptophytes, and cryptophytes) to tertiary predators (e.g., ciliates, dinoflagellates, and choanoflagellates). To advance the understanding of MCM protist ecology and the roles of MCM protists in nutrient and energy cycling, we investigated potential metabolic strategies and microbial interactions of key MCM protists isolated from a well-described lake (Lake Bonney). Fluorescence-activatedmore » cell sorting (FACS) of enrichment cultures, combined with single amplified genome/amplicon sequencing and fluorescence microscopy, revealed that MCM protists possess diverse potential metabolic capabilities and interactions. Two metabolically distinct bacterial clades (FlavobacteriaandMethylobacteriaceae) were independently associated with two key MCM lake microalgae (IsochrysisandChlamydomonas, respectively). We also report on the discovery of two heterotrophic nanoflagellates belonging to the Stramenopila supergroup, one of which lives as a parasite ofChlamydomonas, a dominate primary producer in the shallow, nutrient-poor layers of the lake. Single-cell eukaryotes called protists play critical roles in the cycling of organic matter in aquatic environments. In the ice-covered lakes of Antarctica, protists play key roles in the aquatic food web, providing the majority of organic carbon to the rest of the food web (photosynthetic protists) and acting as the major consumers at the top of the food web (predatory protists). In this study, we utilized a combination of techniques (microscopy, cell sorting, and genomic analysis) to describe the trophic abilities of Antarctic lake protists and their potential interactions with other microbes. Ultimately, our work reveals that Antarctic lake protists rely on metabolic versatility for their energy and nutrient requirements in this unique and isolated environment.« less

Bimetallic Nanocatalysts in Mesoporous Silica for Hydrogen Production from Coal-Derived Fuels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuila, Debasish; Ilias, Shamsuddin

2013-02-13

In steam reforming reactions (SRRs) of alkanes and alcohols to produce H 2, noble metals such as platinum (Pt) and palladium (Pd) are extensively used as catalyst. These metals are expensive; so, to reduce noble-metal loading, bi-metallic nanocatalysts containing non-noble metals in MCM-41 (Mobil Composition of Material No. 41, a mesoporous material) as a support material with high-surface area were synthesized using one-pot hydrothermal procedure with a surfactant such as cetyltrimethylammonium bromide (CTAB) as a template. Bi-metallic nanocatalysts of Pd-Ni and Pd-Co with varying metal loadings in MCM-41 were characterized by x-ray diffraction (XRD), N 2 adsorption, and Transmission electronmore » microscopy (TEM) techniques. The BET surface area of MCM-41 (~1000 m 2/g) containing metal nanoparticles decreases with the increase in metal loading. The FTIR studies confirm strong interaction between Si-O-M (M = Pd, Ni, Co) units and successful inclusion of metal into the mesoporous silica matrix. The catalyst activities were examined in steam reforming of methanol (SRM) reactions to produce hydrogen. Reference tests using catalysts containing individual metals (Pd, Ni and Co) were also performed to investigate the effect of the bimetallic system on the catalytic behavior in the SRM reactions. The bimetallic system remarkably improves the hydrogen selectivity, methanol conversion and stability of the catalyst. The results are consistent with a synergistic behavior for the Pd-Ni-bimetallic system. The performance, durability and thermal stability of the Pd-Ni/MCM-41 and Pd-Co/MCM-41 suggest that these materials may be promising catalysts for hydrogen production from biofuels. A part of this work for synthesis and characterization of Pd-Ni-MCM-41 and its activity for SRM reactions has been published (“Development of Mesoporous Silica Encapsulated Pd-Ni Nanocatalyst for Hydrogen Production” in “Production and Purification of Ultraclean Transportation Fuels”; Hu, Y., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2011.)« less

Magnetic Fe3O4@MCM-41 core-shell nanoparticles functionalized with thiol silane for efficient l-asparaginase immobilization.

PubMed

Ulu, Ahmet; Noma, Samir Abbas Ali; Koytepe, Suleyman; Ates, Burhan

2018-06-06

l-Asparaginase (l-ASNase) is a vital enzyme for medical treatment and food industry. Here, we assessed the use of Fe 3 O 4 @Mobil Composition of Matter No. 41 (MCM-41) magnetic nanoparticles as carrier matrix for l-ASNase immobilization. In addition, surface of Fe 3 O 4 @MCM-41 magnetic nanoparticles was functionalized with 3-mercaptopropyltrimethoxysilane (MPTMS) to enhance stability of l-ASNase. The chemical structure, thermal properties, magnetic profile and morphology of the thiol-functionalized Fe 3 O 4 @MCM-41 magnetic nanoparticles were characterized with Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential thermal analysis (DTA), differential scanning calorimetry (DSC), vibrating sample magnetometer (VSM), scanning electron microscope (SEM), energy dispersive X-ray (EDX) spectroscopy and zeta-potential measurement. l-ASNase was covalently immobilized onto the thiol-functionalized Fe 3 O 4 @MCM-41 magnetic nanoparticles. The properties of the immobilized enzyme, including optimum pH, temperature, kinetic parameters, thermal stability, reusability and storage stability were investigated and compared to free one. Immobilized enzyme was found to be stable over a wide range of pH and temperature range than free enzyme. The immobilized l-ASNase also showed higher thermal stability after 180 min incubation at 50 °C. The immobilized enzyme still retained 63% of its original activity after 16 times of reuse. The Km value for the immobilized enzyme was 1.15-fold lower than the free enzyme, which indicates increased affinity for the substrate. Additionally, the immobilized enzyme was active over 65% and 53% after 30 days of storage at 4 °C and room temperature (∼25 °C), respectively. Thereby, the results confirmed that thiol-functionalized Fe 3 O 4 @MCM-41 magnetic nanoparticles had high efficiency for l-ASNase immobilization and improved stability of L-ASNase.

Synthesis of cobalt-containing mesoporous catalysts using the ultrasonic-assisted “pH-adjusting” method: Importance of cobalt species in styrene oxidation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Baitao, E-mail: btli@scut.edu.cn; Zhu, Yanrun; Jin, Xiaojing

2015-01-15

Cobalt-containing SBA-15 and MCM-41 (Co-SBA-15 and Co-MCM-41) mesoporous catalysts were prepared via ultrasonic-assisted “pH-adjusting” technique in this study. Their physiochemical structures were comprehensively characterized and correlated with catalytic activity in oxidation of styrene. The nature of cobalt species depended on the type of mesoporous silica as well as pH values. The different catalytic performance between Co-SBA-15 and Co-MCM-41 catalysts originated from cobalt species. Cobalt species were homogenously incorporated into the siliceous framework of Co-SBA-15 in single-site Co(II) state, while Co{sub 3}O{sub 4} particles were loaded on Co-MCM-41 catalysts. The styrene oxidation tests showed that the single-site Co(II) state was moremore » beneficial to the catalytic oxidation of styrene. The higher styrene conversion and benzaldehyde selectivity over Co-SBA-15 catalysts were mainly attributed to single-site Co(II) state incorporated into the framework of SBA-15. The highest conversion of styrene (34.7%) with benzaldehyde selectivity of 88.2% was obtained over Co-SBA-15 catalyst prepared at pH of 7.5, at the mole ratio of 1:1 (styrene to H{sub 2}O{sub 2}) at 70 °C. - Graphical abstract: Cobalt-containing mesoporous silica catalysts were developed via ultrasonic-assisted “pH-adjusting” technique. Compared with Co{sub 3}O{sub 4} in Co-MCM-41, the single-site Co(II) state in Co-SBA-15 was more efficient for the styrene oxidation. - Highlights: • Fast and cost-effective ultrasonic technique for preparing mesoporous materials. • Incorporation of Co via ultrasonic irradiation and “pH-adjusting”. • Physicochemical comparison between Co-SBA-15 and Co-MCM-41. • Correlation of styrene oxidation activity and catalyst structural property.« less

Solid State NMR Characterization of Ibuprofen:Nicotinamide Cocrystals and New Idea for Controlling Release of Drugs Embedded into Mesoporous Silica Particles.

PubMed

Skorupska, Ewa; Kaźmierski, Sławomir; Potrzebowski, Marek J

2017-05-01

Grinding and melting methods were employed for synthesis of pharmaceutical cocrystals formed by racemic (R/S) and entiomeric (S) ibuprofen (IBU) and nicotinamide (NA) as coformer. Obtained (R/S)-IBU:NA and (S)-IBU:NA cocrystals were fully characterized by means of advanced one- and two-dimensional solid state nuclear magnetic resonance (SS NMR) techniques with very fast magic angle spinning (MAS) at 60 kHz. The distinction in molecular packing and specific hydrogen bonding pattern was clearly recognized by analysis of 1 H, 13 C, and 15 N spectra. It is concluded from these studies that both methods (grinding and melting) provide exactly the same, specific forms of cocrystals. Thermal solvent-free (TSF) approach was used for loading of (R/S)-IBU:NA and (S)-IBU:NA into the pores of MCM-41 mesoporous silica particle (MSP). The progress and efficiency of this process was analyzed by NMR spectroscopy. It has been confirmed that TSF method is an effective and safe technique of filling the MSP pores with active pharmaceutical ingredients (APIs). By analyzing the NMR results, it has been further proved that excess of IBU and NA components, which are not embedded into the pores during melting and cooling, crystallize on the MCM-41 walls preserving very specific arrangement, characteristic for crystalline samples. By investigating kinetic of release for (R/S)-IBU/MCM-41, (S)-IBU:NA/MCM-41, and (R/S)-IBU:NA/MCM-41 samples containing active components exclusively inside of the pores, it was revealed that release of IBU is much faster for the first of the samples compared to those containing IBU and NA inside the pores. The hypothesis that the rate of release of API can be controlled by specific composition of cocrystal embedded into the MSP pore was further supported by study of (R/S)-IBU:BA/MCM-41 sample with benzoic acid (BA) as coformer.

Investigating the Heavy Metal Adsorption of Mesoporous Silica Materials Prepared by Microwave Synthesis

NASA Astrophysics Data System (ADS)

Zhu, Wenjie; Wang, Jingxuan; Wu, Di; Li, Xitong; Luo, Yongming; Han, Caiyun; Ma, Wenhui; He, Sufang

2017-05-01

Mesoporous silica materials (MSMs) of the MCM-41 type were rapidly synthesized by microwave heating using silica fume as silica source and evaluated as adsorbents for the removal of Cu2+, Pb2+, and Cd2+ from aqueous solutions. The effects of microwave heating times on the pore structure of the resulting MSMs were investigated as well as the effects of different acids which were employed to adjust the solution pH during the synthesis. The obtained MCM-41 samples were characterized by nitrogen adsorption-desorption analyses, X-ray powder diffraction, and transmission electron microscopy. The results indicated that microwave heating method can significantly reduce the synthesis time of MCM-41 to 40 min. The MCM-41 prepared using citric acid (c-MCM-41(40)) possessed more ordered hexagonal mesostructure, higher pore volume, and pore diameter. We also explored the ability of c-MCM-41(40) for removing heavy metal ions (Cu2+, Pb2+, and Cd2+) from aqueous solution and evaluated the influence of pH on its adsorption capacity. In addition, the adsorption isotherms were fitted by Langmuir and Freundlich models, and the adsorption kinetics were assessed using pseudo-first-order and pseudo-second-order models. The intraparticle diffusion model was studied to understand the adsorption process and mechanism. The results confirmed that the as-synthesized adsorbent could efficiently remove the heavy metal ions from aqueous solution at pH range of 5-7. The adsorption isotherms obeyed the Langmuir model, and the maximum adsorption capacities of the adsorbent for Cu2+, Pb2+, and Cd2+ were 36.3, 58.5, and 32.3 mg/g, respectively. The kinetic data were well fitted to the pseudo-second-order model, and the results of intraparticle diffusion model showed complex chemical reaction might be involved during adsorption process.

Ultrastructural and Single-Cell-Level Characterization Reveals Metabolic Versatility in a Microbial Eukaryote Community from an Ice-Covered Antarctic Lake

DOE PAGES

Li, Wei; Podar, Mircea; Morgan-Kiss, Rachael M.

2016-04-15

The McMurdo Dry Valleys (MCM) of southern Victoria Land, Antarctica, harbor numerous ice-covered bodies of water that provide year-round liquid water oases for isolated food webs dominated by the microbial loop. Single-cell microbial eukaryotes (protists) occupy major trophic positions within this truncated food web, ranging from primary producers (e.g., chlorophytes, haptophytes, and cryptophytes) to tertiary predators (e.g., ciliates, dinoflagellates, and choanoflagellates). To advance the understanding of MCM protist ecology and the roles of MCM protists in nutrient and energy cycling, we investigated potential metabolic strategies and microbial interactions of key MCM protists isolated from a well-described lake (Lake Bonney). Fluorescence-activatedmore » cell sorting (FACS) of enrichment cultures, combined with single amplified genome/amplicon sequencing and fluorescence microscopy, revealed that MCM protists possess diverse potential metabolic capabilities and interactions. Two metabolically distinct bacterial clades (FlavobacteriaandMethylobacteriaceae) were independently associated with two key MCM lake microalgae (IsochrysisandChlamydomonas, respectively). We also report on the discovery of two heterotrophic nanoflagellates belonging to the Stramenopila supergroup, one of which lives as a parasite ofChlamydomonas, a dominate primary producer in the shallow, nutrient-poor layers of the lake. Single-cell eukaryotes called protists play critical roles in the cycling of organic matter in aquatic environments. In the ice-covered lakes of Antarctica, protists play key roles in the aquatic food web, providing the majority of organic carbon to the rest of the food web (photosynthetic protists) and acting as the major consumers at the top of the food web (predatory protists). In this study, we utilized a combination of techniques (microscopy, cell sorting, and genomic analysis) to describe the trophic abilities of Antarctic lake protists and their potential interactions with other microbes. Ultimately, our work reveals that Antarctic lake protists rely on metabolic versatility for their energy and nutrient requirements in this unique and isolated environment.« less

Modified Interior Distance Functions (Theory and Methods)

NASA Technical Reports Server (NTRS)

Polyak, Roman A.

1995-01-01

In this paper we introduced and developed the theory of Modified Interior Distance Functions (MIDF's). The MIDF is a Classical Lagrangian (CL) for a constrained optimization problem which is equivalent to the initial one and can be obtained from the latter by monotone transformation both the objective function and constraints. In contrast to the Interior Distance Functions (IDF's), which played a fundamental role in Interior Point Methods (IPM's), the MIDF's are defined on an extended feasible set and along with center, have two extra tools, which control the computational process: the barrier parameter and the vector of Lagrange multipliers. The extra tools allow to attach to the MEDF's very important properties of Augmented Lagrangeans. One can consider the MIDFs as Interior Augmented Lagrangeans. It makes MIDF's similar in spirit to Modified Barrier Functions (MBF's), although there is a fundamental difference between them both in theory and methods. Based on MIDF's theory, Modified Center Methods (MCM's) have been developed and analyzed. The MCM's find an unconstrained minimizer in primal space and update the Lagrange multipliers, while both the center and the barrier parameter can be fixed or updated at each step. The MCM's convergence was investigated, and their rate of convergence was estimated. The extension of the feasible set and the special role of the Lagrange multipliers allow to develop MCM's, which produce, in case of nondegenerate constrained optimization, a primal and dual sequences that converge to the primal-dual solutions with linear rate, even when both the center and the barrier parameter are fixed. Moreover, every Lagrange multipliers update shrinks the distance to the primal dual solution by a factor 0 less than gamma less than 1 which can be made as small as one wants by choosing a fixed interior point as a 'center' and a fixed but large enough barrier parameter. The numericai realization of MCM leads to the Newton MCM (NMCM). The approximation for the primal minimizer one finds by Newton Method followed by the Lagrange multipliers update. Due to the MCM convergence, when both the center and the barrier parameter are fixed, the condition of the MDF Hessism and the neighborhood of the primal ninimizer where Newton method is 'well' defined remains stable. It contributes to both the complexity and the numerical stability of the NMCM.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vendeix, Franck A.P.; Murphy, IV, Frank V.; Cantara, William A.

Human tRNA Lys3 UUU (htRNA Lys3 UUU) decodes the lysine codons AAA and AAG during translation and also plays a crucial role as the primer for HIV-1 (human immunodeficiency virus type 1) reverse transcription. The posttranscriptional modifications 5-methoxycarbonylmethyl-2-thiouridine (mcm 5s 2U 34), 2-methylthio-N 6-threonylcarbamoyladenosine (ms 2t 6A 37), and pseudouridine (Ψ 39) in the tRNA's anticodon domain are critical for ribosomal binding and HIV-1 reverse transcription. To understand the importance of modified nucleoside contributions, we determined the structure and function of this tRNA's anticodon stem and loop (ASL) domain with these modifications at positions 34, 37, and 39, respectively (hASLmore » Lys3 UUU-mcm 5s 2U 34;ms 2t 6A 37;Ψ 39). Ribosome binding assays in vitro revealed that the hASL Lys3 UUU-mcm 5s 2U 34;ms 2t 6A 37;Ψ 39 bound AAA and AAG codons, whereas binding of the unmodified ASL Lys3 UUU was barely detectable. The UV hyperchromicity, the circular dichroism, and the structural analyses indicated that Ψ 39 enhanced the thermodynamic stability of the ASL through base stacking while ms 2t 6A 37 restrained the anticodon to adopt an open loop conformation that is required for ribosomal binding. The NMR-restrained molecular-dynamics-derived solution structure revealed that the modifications provided an open, ordered loop for codon binding. The crystal structures of the hASL Lys3 UUU-mcm 5s 2U 34;ms 2t 6A 37;Ψ 39 bound to the 30S ribosomal subunit with each codon in the A site showed that the modified nucleotides mcm 5s 2U 34 and ms 2t 6A 37 participate in the stability of the anticodon–codon interaction. Importantly, the mcm 5s 2U 34·G 3 wobble base pair is in the Watson–Crick geometry, requiring unusual hydrogen bonding to G in which mcm 5s 2U 34 must shift from the keto to the enol form. The results unambiguously demonstrate that modifications pre-structure the anticodon as a key prerequisite for efficient and accurate recognition of cognate and wobble codons.« less

Partition resampling and extrapolation averaging: approximation methods for quantifying gene expression in large numbers of short oligonucleotide arrays.

PubMed

Goldstein, Darlene R

2006-10-01

Studies of gene expression using high-density short oligonucleotide arrays have become a standard in a variety of biological contexts. Of the expression measures that have been proposed to quantify expression in these arrays, multi-chip-based measures have been shown to perform well. As gene expression studies increase in size, however, utilizing multi-chip expression measures is more challenging in terms of computing memory requirements and time. A strategic alternative to exact multi-chip quantification on a full large chip set is to approximate expression values based on subsets of chips. This paper introduces an extrapolation method, Extrapolation Averaging (EA), and a resampling method, Partition Resampling (PR), to approximate expression in large studies. An examination of properties indicates that subset-based methods can perform well compared with exact expression quantification. The focus is on short oligonucleotide chips, but the same ideas apply equally well to any array type for which expression is quantified using an entire set of arrays, rather than for only a single array at a time. Software implementing Partition Resampling and Extrapolation Averaging is under development as an R package for the BioConductor project.

EVALUATING REGIONAL PREDICTIVE CAPACITY OF A PROCESS-BASED MERCURY EXPOSURE MODEL, REGIONAL-MERCURY CYCLING MODEL (R-MCM), APPLIED TO 91 VERMONT AND NEW HAMPSHIRE LAKES AND PONDS, USA

EPA Science Inventory

Regulatory agencies must develop fish consumption advisories for many lakes and rivers with limited resources. Process-based mathematical models are potentially valuable tools for developing regional fish advisories. The Regional Mercury Cycling model (R-MCM) was specifically d...

Alternative technological development for RF hybridization

NASA Astrophysics Data System (ADS)

Antônio Finardi, Célio; da Fontoura Ponchet, André; Battesini Adamo, Cristina; Flacker, Alexander; Cotrin Teixeira, Ricardo; Panepucci, Roberto Ricardo

2017-03-01

The paper presents a technological solution for high frequency packaging platform evaluated up to 40 GHz. The main purpose of this development was to define an alternative hybrid technology that is more flexible and faster to prototype compared with thin film or multi chip module (MCM-D). The alternative technology also shows adequate performance for high bit rate solutions integrating optical and electronics blocks. This approach consists of a soft substrate (laminate material), plating processes (electroless Ni-P/Au, electrolytic Au) and lithography patterning. Ground coplanar waveguide was used for microwave structures with excellent ground planes connections due to easy via holes implementation. We present results of high frequency packaging of important RF blocks, such as integrated broadband bias-T, transimpedance amplifier ICs and silicon photonics optical modulators. The paper demonstrates a solution for high frequency hybridization that can be implemented with standard substrates, designed with any shape and with large numbers of metalized via holes and compatible with usual assembling techniques.

Quaternary ammonium-functionalized MCM-48 mesoporous silica as a sorbent for the dispersive solid-phase extraction of endocrine disrupting compounds in water.

PubMed

Zhang, Shijuan; Lu, Fengli; Ma, Xiaoyun; Yue, Mingbo; Li, Yanxin; Liu, Jiammin; You, Jinmao

2018-07-06

MCM-48 mesoporous silica was functionalized with dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride, a quaternary ammonium salt with a long hydrophobic chain, to prepare a new sorbent for the dispersive solid-phase extraction (DSPE) of seven endocrine disrupting compounds (EDCs) including 4-hexylphenol, 4-octylphenol, 4-nonylphenol, bisphenol A, estrone, 17β-estradiol and estriol in water. A series of differently functionalized MCM-48 materials were also synthesized, and they served as reference materials to study the mechanism. The developed DSPE method was combined with HPLC with fluorescence detection to evaluate the adsorption performance. The results indicated that the quaternary ammonium-functionalized MCM-48 mesoporous silica can be used as ideal sorbent for EDCs in water with recoveries of higher than 95% due to the electrostatic interactions and hydrophobic effect. Hydrogen bonding and π-π interactions in other synthesized materials could lead to about 25-30% increase in recoveries, but the results for polyhydroxy compounds were still not satisfying. The quaternary ammonium-functionalized MCM-48 mesoporous silica was successfully applied to the DSPE of EDCs in real water samples. The optimum extraction conditions were sorbent amount, 15 mg; desorption time; 5 min; elution volume, 0.8 mL; sample pH 3.0; and salt addition, 5 g/L. The limits of detection were in the range of 1.2-2.6 ng/L, while the limits of quantitation were in the range of 4.3-8.3 ng/L. Copyright © 2018 Elsevier B.V. All rights reserved.

Characterization of conserved arginine residues on Cdt1 that affect licensing activity and interaction with Geminin or Mcm complex.

PubMed

You, Zhiying; Ode, Koji L; Shindo, Mayumi; Takisawa, Haruhiko; Masai, Hisao

2016-05-02

All organisms ensure once and only once replication during S phase through a process called replication licensing. Cdt1 is a key component and crucial loading factor of Mcm complex, which is a central component for the eukaryotic replicative helicase. In higher eukaryotes, timely inhibition of Cdt1 by Geminin is essential to prevent rereplication. Here, we address the mechanism of DNA licensing using purified Cdt1, Mcm and Geminin proteins in combination with replication in Xenopus egg extracts. We mutagenized the 223th arginine of mouse Cdt1 (mCdt1) to cysteine or serine (R-S or R-C, respectively) and 342nd and 346th arginines constituting an arginine finger-like structure to alanine (RR-AA). The RR-AA mutant of Cdt1 could not only rescue the DNA replication activity in Cdt1-depleted extracts but also its specific activity for DNA replication and licensing was significantly increased compared to the wild-type protein. In contrast, the R223 mutants were partially defective in rescue of DNA replication and licensing. Biochemical analyses of these mutant Cdt1 proteins indicated that the RR-AA mutation disabled its functional interaction with Geminin, while R223 mutations resulted in ablation in interaction with the Mcm2∼7 complex. Intriguingly, the R223 mutants are more susceptible to the phosphorylation-induced inactivation or chromatin dissociation. Our results show that conserved arginine residues play critical roles in interaction with Geminin and Mcm that are crucial for proper conformation of the complexes and its licensing activity.

Automated Design of Board and MCM Level Digital Systems.

DTIC Science & Technology

1997-10-01

Partitioning for Multicomponent Synthesis 159 Appendix K: Resource Constrained RTL Partitioning for Synthesis of Multi- FPGA Designs 169 Appendix L...digital signal processing) ar- chitectures. These target architectures, illustrated in Figure 1, can contain application-specific ASICS, FPGAs ...synthesis tools for ASIC, FPGA and MCM synthesis (Figure 8). Multicomponent Partitioning Engine The par- titioning engine is a hierarchical partitioning

75 FR 60694 - Taking and Importing Marine Mammals; Naval Explosive Ordnance Disposal School Training Operations...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-01

... Countermeasures (MCM) detonations is one function of the U.S. Navy EOD force, which involves mine-hunting and mine... of SRI for a portion of the NEODS class. The NEODS would utilize areas approximately one to three nmi... the training is to give NEODS students the tools and techniques to implement MCM through real...

GOATS 2008 Autonomous, Adaptive Multistatic Acoustic Sensing

DTIC Science & Technology

2008-09-30

To develop net-centric, autonomous underwater vehicle sensing concepts for littoral MCM and ASW, exploiting collaborative and environmentally...unlimited 13. SUPPLEMENTARY NOTES code 1 only 14. ABSTRACT To develop net-centric, autonomous underwater vehicle sensing concepts for littoral MCM and...of autonomous underwater vehicle networks as platforms for new sonar concepts exploring the full 3-D acoustic environment of shallow water (SW) and

Synthesis, structure and magnetic properties of porous magnetic composite, based on MCM-41 molecular sieve with Fe{sub 3}O{sub 4} nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kolotilov, Sergey V.; Shvets, Oleksiy; Cador, Olivier

2006-08-15

Porous magnetic composites were prepared by the synthesis of molecular sieve MCM-41 in the presence of Fe{sub 3}O{sub 4} nanoparticles with average diameter of 15 nm. Nanoparticles were captured by porous silica matrix MCM-41, which resulted in their incorporation, as it was confirmed by TEM, SEM and X-ray diffraction. The materials possessed high surface area (392-666 m{sup 2} g{sup -1}), high pore volume (0.39-0.73 cm{sup 3} g{sup -1}) along with high magnetic response (M {sub S} up to 28.4 emu g{sup -1} at 300 K). Calcination of samples resulted in partial oxidation of Fe{sub 3}O{sub 4} to {alpha}-Fe{sub 2}O{sub 3}.more » The influence of nanoparticles content on sorption and magnetic properties of the composites was shown. No hysteresis was found for the samples at 300 K; at 5 K, H {sub C} was in the range 370-385 G for non-calcinated samples and 350-356 G for calcinated ones. - Graphical abstract: Schematic presentation of MCM-41/Fe{sub 3}O{sub 4} composite.« less

Adsorption of heavy metals on amine-functionalized MCM-48

NASA Astrophysics Data System (ADS)

Taba, P.; Budi, P.; Puspitasari, A. Y.

2017-04-01

The ordered mesoporous silica with cubic structure, MCM-48 was synthesized by post-synthesis under basic media using colloidal silica, cetyltrimethylammonium bromide, and Triton X-100. The modified material, NH2-MCM-48 was prepared using 3-aminopropyl trimetoxysilane (3-APTMS). X-ray diffraction and FT-IR were used to characterize the samples. The modified material was utilized for adsorption of Cu2+and Mn2+ from aqueous solution. Parameters used for studying the adsorption process were pH, time of contact, and the initial concentrations of Cu2+ and Mn2+ ions. Desorption of ions from the adsorbent was also studied using several desorbing agents. The pseudo-second order was found to be the kinetic order for the metals adsorption. The adsorption of Cu2+ and Mn2+ on NH2-MCM-48 was fixed by the Langmuir model better than the Freundlich model with the capacity of 0.52 and 0.80 mmol g-1 for Cu2+ and Mn2+, respectively. The best desorbing agents for removing the adsorbed Cu2+ and Mn2+ from the adsorbent were 1 M HNO3 and 1 M HC1, respectively.

Simulation of unsteady flows by the DSMC macroscopic chemistry method

NASA Astrophysics Data System (ADS)

Goldsworthy, Mark; Macrossan, Michael; Abdel-jawad, Madhat

2009-03-01

In the Direct Simulation Monte-Carlo (DSMC) method, a combination of statistical and deterministic procedures applied to a finite number of 'simulator' particles are used to model rarefied gas-kinetic processes. In the macroscopic chemistry method (MCM) for DSMC, chemical reactions are decoupled from the specific particle pairs selected for collisions. Information from all of the particles within a cell, not just those selected for collisions, is used to determine a reaction rate coefficient for that cell. Unlike collision-based methods, MCM can be used with any viscosity or non-reacting collision models and any non-reacting energy exchange models. It can be used to implement any reaction rate formulations, whether these be from experimental or theoretical studies. MCM has been previously validated for steady flow DSMC simulations. Here we show how MCM can be used to model chemical kinetics in DSMC simulations of unsteady flow. Results are compared with a collision-based chemistry procedure for two binary reactions in a 1-D unsteady shock-expansion tube simulation. Close agreement is demonstrated between the two methods for instantaneous, ensemble-averaged profiles of temperature, density and species mole fractions, as well as for the accumulated number of net reactions per cell.

A Novel Multilayer Correlation Maximization Model for Improving CCA-Based Frequency Recognition in SSVEP Brain-Computer Interface.

PubMed

Jiao, Yong; Zhang, Yu; Wang, Yu; Wang, Bei; Jin, Jing; Wang, Xingyu

2018-05-01

Multiset canonical correlation analysis (MsetCCA) has been successfully applied to optimize the reference signals by extracting common features from multiple sets of electroencephalogram (EEG) for steady-state visual evoked potential (SSVEP) recognition in brain-computer interface application. To avoid extracting the possible noise components as common features, this study proposes a sophisticated extension of MsetCCA, called multilayer correlation maximization (MCM) model for further improving SSVEP recognition accuracy. MCM combines advantages of both CCA and MsetCCA by carrying out three layers of correlation maximization processes. The first layer is to extract the stimulus frequency-related information in using CCA between EEG samples and sine-cosine reference signals. The second layer is to learn reference signals by extracting the common features with MsetCCA. The third layer is to re-optimize the reference signals set in using CCA with sine-cosine reference signals again. Experimental study is implemented to validate effectiveness of the proposed MCM model in comparison with the standard CCA and MsetCCA algorithms. Superior performance of MCM demonstrates its promising potential for the development of an improved SSVEP-based brain-computer interface.

[Influence exogenous nicotinamide adenine dinucleotide (NAD+) on contractile and bioelectric activity of the rat heart].

PubMed

Pustovit, K B; Kuz'min, V S; Sukhova, G S

2014-04-01

This study is aimed to the investigation of the nicotinamide adenine dinucleotide (NAD+) effects and mechanisms of action in a heart. NAD+ (mcM) induces multiphase alternation of contractile activity of isolated rat heart: short positive inotropic action is followed by a negative inotropic phase. NAD+ (1-100 mcM) induces decreasing of action potential duration (APD) in rat atrial myocardium (from 45 +/- 0.82 ms in control experiments to 39 +/- 1.05 (n = 8) and 32 +/- 2 (n = 8) during application of 10 and 100 mcM of NAD+, respectively). Significant APD increase (from 45 +/- 0.82 ms to 74 +/- 1.89 (n = 8) ms) was observed during washing out of NAD+ (100 mcM). ATP or adenosine was unable to increase APD both during application or washing out. NAD+ induced APD decrease was not suppressed by P1-antagonist theophylline. P1-purinoreceptor and metabolite independent direct action of NAD+ in rat heart is suggested. Activation of P2X or P2Y receptors, cyclic ADP-ribose accumulation in cardiomyocytes is proposed as a main mechanism of NAD(+)-induced effects in the heart.

NASA Tech Briefs, February 2007

NASA Technical Reports Server (NTRS)

2007-01-01

Topics covered include: Calibration Test Set for a Phase-Comparison Digital Tracker; Wireless Acoustic Measurement System; Spiral Orbit Tribometer; Arrays of Miniature Microphones for Aeroacoustic Testing; Predicting Rocket or Jet Noise in Real Time; Computational Workbench for Multibody Dynamics; High-Power, High-Efficiency Ka-Band Space Traveling-Wave Tube; Gratings and Random Reflectors for Near-Infrared PIN Diodes; Optically Transparent Split-Ring Antennas for 1 to 10 GHz; Ice-Penetrating Robot for Scientific Exploration; Power-Amplifier Module for 145 to 165 GHz; Aerial Videography From Locally Launched Rockets; SiC Multi-Chip Power Modules as Power-System Building Blocks; Automated Design of Restraint Layer of an Inflatable Vessel; TMS for Instantiating a Knowledge Base With Incomplete Data; Simulating Flights of Future Launch Vehicles and Spacecraft; Control Code for Bearingless Switched- Reluctance Motor; Machine Aided Indexing and the NASA Thesaurus; Arbitrating Control of Control and Display Units; Web-Based Software for Managing Research; Driver Code for Adaptive Optics; Ceramic Paste for Patching High-Temperature Insulation; Fabrication of Polyimide-Matrix/Carbon and Boron-Fiber Tape; Protective Skins for Aerogel Monoliths; Code Assesses Risks Posed by Meteoroids and Orbital Debris; Asymmetric Bulkheads for Cylindrical Pressure Vessels; Self-Regulating Water-Separator System for Fuel Cells; Self-Advancing Step-Tap Drills; Array of Bolometers for Submillimeter- Wavelength Operation; Delta-Doped CCDs as Detector Arrays in Mass Spectrometers; Arrays of Bundles of Carbon Nanotubes as Field Emitters; Staggering Inflation To Stabilize Attitude of a Solar Sail; and Bare Conductive Tether for Decelerating a Spacecraft.

Boeing's STAR-FODB test results

NASA Astrophysics Data System (ADS)

Fritz, Martin E.; de la Chapelle, Michael; Van Ausdal, Arthur W.

1995-05-01

Boeing has successfully concluded a 2 1/2 year, two phase developmental contract for the STAR-Fiber Optic Data Bus (FODB) that is intended for future space-based applications. The first phase included system analysis, trade studies, behavior modeling, and architecture and protocal selection. During this phase we selected AS4074 Linear Token Passing Bus (LTPB) protocol operating at 200 Mbps, along with the passive, star-coupled fiber media. The second phase involved design, build, integration, and performance and environmental test of brassboard hardware. The resulting brassboard hardware successfully passed performance testing, providing 200 Mbps operation with a 32 X 32 star-coupled medium. This hardware is suitable for a spaceflight experiment to validate ground testing and analysis and to demonstrate performace in the intended environment. The fiber bus interface unit (FBIU) is a multichip module containing transceiver, protocol, and data formatting chips, buffer memory, and a station management controller. The FBIU has been designed for low power, high reliability, and radiation tolerance. Nine FBIUs were built and integrated with the fiber optic physical layer consisting of the fiber cable plant (FCP) and star coupler assembly (SCA). Performance and environmental testing, including radiation exposure, was performed on selected FBIUs and the physical layer. The integrated system was demonstrated with a full motion color video image transfer across the bus while simultaneously performing utility functions with a fiber bus control module (FBCM) over a telemetry and control (T&C) bus, in this case AS1773.

MM&T for VHSIC Multichip Packages

DTIC Science & Technology

1989-09-20

broader the network bandwidth must be in order to preserve the integrity of the rising and falling edges of the signal. However, for very fast ...inch of path length adds approximately 100-300 ps of delay to the signal. System designers of fast ECL type devices must incorporate these delays into... intermittently in low temperature areas. Permanent changes in operating characteristics and physical damage produced during temperature shock occur

Co-modified MCM-41 as an effective adsorbent for levofloxacin removal from aqueous solution: optimization of process parameters, isotherm, and thermodynamic studies.

PubMed

Jin, Ting; Yuan, Wenhua; Xue, Yujie; Wei, Hong; Zhang, Chaoying; Li, Kebin

2017-02-01

Antibiotics are emerging contaminants due to their potential risks to human health and ecosystems. Poor biodegradability makes it necessary to develop effective physical-chemical methods to eliminate these contaminants from water. The cobalt-modified MCM-41 was prepared by a one-pot hydrothermal method and characterized by SAXRD, N 2 adsorption-desorption, SEM, UV-Vis DR, and FTIR spectroscopy. The results revealed that the prepared 3% Co-MCM-41 possessed mesoporous structure with BET surface areas at around 898.5 m 2 g -1 . The adsorption performance of 3% Co-MCM-41 toward levofloxacin (LVF) was investigated by batch experiments. The adsorption of LVF on 3% Co-MCM-41 was very fast and reached equilibrium within 2 h. The adsorption kinetics followed the pseudo-second-order kinetic model with the second-order rate constants in the range of 0.00198-0.00391 g mg -1  min -1 . The adsorption isotherms could be well represented by the Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherm equations. Nevertheless, D-R isotherm provided the best fit based on the coefficient of determination and average relative error values. The mean free energy of adsorption (E) calculated from D-R model was about 11 kJ mol -1 , indicating that the adsorption was mainly governed by a chemisorption process. Moreover, the adsorption capacity was investigated as a function of pH, adsorbent dosage, LVF concentration, and temperature with help of respond surface methodology (RSM). A quadratic model was established, and an optimal condition was obtained as follows: pH 8.5, adsorbent dosage of 1 g L -1 , initial LVF concentration of 119.8 mg L -1 , and temperature of 31.6 °C. Under the optimal condition, the adsorption capacity of 3% Co-MCM-41 to LVF could reach about 108.1 mg g -1 . The solution pH, adsorbent dosage, LVF concentration, and a combination of adsorbent dose and LVF concentration were significant factors affecting the adsorption process. The adsorption thermodynamic functions were also determined. The negative ΔH 0 (-33.50 kJ mol -1 ) and ΔS 0 (-43.57 J mol -1  K -1 ) suggested that the adsorption was an exothermic process accompanied by decreasing disorder. This study may indicate that 3% Co-MCM-41 is a promising adsorbent for removing emerging pollutants of LVF from water.

Human tRNA(Lys3)(UUU) is pre-structured by natural modifications for cognate and wobble codon binding through keto-enol tautomerism.

PubMed

Vendeix, Franck A P; Murphy, Frank V; Cantara, William A; Leszczyńska, Grażyna; Gustilo, Estella M; Sproat, Brian; Malkiewicz, Andrzej; Agris, Paul F

2012-03-02

Human tRNA(Lys3)(UUU) (htRNA(Lys3)(UUU)) decodes the lysine codons AAA and AAG during translation and also plays a crucial role as the primer for HIV-1 (human immunodeficiency virus type 1) reverse transcription. The posttranscriptional modifications 5-methoxycarbonylmethyl-2-thiouridine (mcm(5)s(2)U(34)), 2-methylthio-N(6)-threonylcarbamoyladenosine (ms(2)t(6)A(37)), and pseudouridine (Ψ(39)) in the tRNA's anticodon domain are critical for ribosomal binding and HIV-1 reverse transcription. To understand the importance of modified nucleoside contributions, we determined the structure and function of this tRNA's anticodon stem and loop (ASL) domain with these modifications at positions 34, 37, and 39, respectively (hASL(Lys3)(UUU)-mcm(5)s(2)U(34);ms(2)t(6)A(37);Ψ(39)). Ribosome binding assays in vitro revealed that the hASL(Lys3)(UUU)-mcm(5)s(2)U(34);ms(2)t(6)A(37);Ψ(39) bound AAA and AAG codons, whereas binding of the unmodified ASL(Lys3)(UUU) was barely detectable. The UV hyperchromicity, the circular dichroism, and the structural analyses indicated that Ψ(39) enhanced the thermodynamic stability of the ASL through base stacking while ms(2)t(6)A(37) restrained the anticodon to adopt an open loop conformation that is required for ribosomal binding. The NMR-restrained molecular-dynamics-derived solution structure revealed that the modifications provided an open, ordered loop for codon binding. The crystal structures of the hASL(Lys3)(UUU)-mcm(5)s(2)U(34);ms(2)t(6)A(37);Ψ(39) bound to the 30S ribosomal subunit with each codon in the A site showed that the modified nucleotides mcm(5)s(2)U(34) and ms(2)t(6)A(37) participate in the stability of the anticodon-codon interaction. Importantly, the mcm(5)s(2)U(34)·G(3) wobble base pair is in the Watson-Crick geometry, requiring unusual hydrogen bonding to G in which mcm(5)s(2)U(34) must shift from the keto to the enol form. The results unambiguously demonstrate that modifications pre-structure the anticodon as a key prerequisite for efficient and accurate recognition of cognate and wobble codons. Copyright © 2011 Elsevier Ltd. All rights reserved.

Comparative study of hydrogen storage on metal doped mesoporous materials

NASA Astrophysics Data System (ADS)

Carraro, P. M.; Sapag, K.; Oliva, M. I.; Eimer, G. A.

2018-06-01

The hydrogen adsorption capacity of mesoporous materials MCM-41 modified with Co, Fe, Ti, Mg and Ni at 77 K and 10 bar was investigated. Various techniques including XRD, N2 adsorption and DRUV-vis were employed for the materials characterization. The results showed that a low nickel loading on MCM-41 support promoted the presence of hydrogen-favorable sites, increasing the hydrogen storage capacity.

Enrichment of extruded snack products with coproducts from chestnut mushroom (Agrocybe aegerita) production: interactions between dietary fiber, physicochemical characteristics, and glycemic load.

PubMed

Brennan, Margaret A; Derbyshire, Emma; Tiwari, Brijesh K; Brennan, Charles S

2012-05-02

Mushrooms are a common vegetable product that have also been linked to pharmaceutical and medicinal uses. However, the production of the fruiting bodies of mushrooms results in a large quantity of food waste in the form of spent compost. Hyphae and the base of fruit bodies from Agrocybe aegerita were retrieved from spent mushroom compost and refined as a freeze-dried powder. This fiber-rich ingredient was used in the manufacture of ready-to-eat extruded cereal snack products. Inclusions rates were 0, 5, 10, and 15% w/w replacement levels for wheat flour from a control recipe. Inclusion of mushroom coproduct material (MCM) was significantly correlated to increased product expansion (r = 0.848) and density (r = 0.949) but negatively correlated to water absorption index (WAI; r = -0.928) and water solubility index (WSI; r = -0.729). Fiber content could not be correlated to differences in pasting properties of extruded snacks even though snack products with MCM showed significantly lower final viscosity values compared to the control. The potential glycemic response of foods was significantly lowered by including MCM (p < 0.05) with a negative correlation between fiber content and overall AUC following a standardized in vitro digestion method (r = -0.910). Starch content, WAI, and WSI were positively correlated to AUC of extruded snacks (r = 0.916, 0.851, and 0.878. respectively). The results illustrate a reduction in the potential glycemic response from including 5% (w/w) of MCM in extruded snacks exceeds 20%. Thus, the incorporation of MCM in ready-to-eat snack foods may be of considerable interest to the food industry in trying to regulate the glycemic response of foods.

Marker Configuration Model-Based Roentgen Fluoroscopic Analysis.

PubMed

Garling, Eric H; Kaptein, Bart L; Geleijns, Koos; Nelissen, Rob G H H; Valstar, Edward R

2005-04-01

It remains unknown if and how the polyethylene bearing in mobile bearing knees moves during dynamic activities with respect to the tibial base plate. Marker Configuration Model-Based Roentgen Fluoroscopic Analysis (MCM-based RFA) uses a marker configuration model of inserted tantalum markers in order to accurately estimate the pose of an implant or bone using single plane Roentgen images or fluoroscopic images. The goal of this study is to assess the accuracy of (MCM-Based RFA) in a standard fluoroscopic set-up using phantom experiments and to determine the error propagation with computer simulations. The experimental set-up of the phantom study was calibrated using a calibration box equipped with 600 tantalum markers, which corrected for image distortion and determined the focus position. In the computer simulation study the influence of image distortion, MC-model accuracy, focus position, the relative distance between MC-models and MC-model configuration on the accuracy of MCM-Based RFA were assessed. The phantom study established that the in-plane accuracy of MCM-Based RFA is 0.1 mm and the out-of-plane accuracy is 0.9 mm. The rotational accuracy is 0.1 degrees. A ninth-order polynomial model was used to correct for image distortion. Marker-Based RFA was estimated to have, in a worst case scenario, an in vivo translational accuracy of 0.14 mm (x-axis), 0.17 mm (y-axis), 1.9 mm (z-axis), respectively, and a rotational accuracy of 0.3 degrees. When using fluoroscopy to study kinematics, image distortion and the accuracy of models are important factors, which influence the accuracy of the measurements. MCM-Based RFA has the potential to be an accurate, clinically useful tool for studying kinematics after total joint replacement using standard equipment.

Suppression of ERβ signaling via ERβ knockout or antagonist protects against bladder cancer development.

PubMed

Hsu, Iawen; Chuang, Kun-Lung; Slavin, Spencer; Da, Jun; Lim, Wei-Xun; Pang, See-Tong; O'Brien, Jeanne H; Yeh, Shuyuan

2014-03-01

Epidemiological studies showed that women have a lower bladder cancer (BCa) incidence, yet higher muscle-invasive rates than men, suggesting that estrogen and the estrogen receptors, estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ), may play critical roles in BCa progression. Using in vitro cell lines and an in vivo carcinogen N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN)-induced mouse BCa model, we found that ERβ plays a positive role in promoting BCa progression. Knockdown of ERβ with ERβ-shRNA in ERβ-positive human BCa J82, 647v and T24 cell lines led to suppressed cell growth and invasion. Mice lacking ERβ have less cancer incidence with reduced expression of the proliferation marker Ki67 in BBN-induced BCa. Consistently, our results show that non-malignant urothelial cells with ERβ knockdown are more resistant to carcinogen-induced malignant transformation. Mechanism dissection found that targeting ERβ suppressed the expression of minichromosome maintenance complex component 5 (MCM5), a DNA replication licensing factor that is involved in tumor cell growth. Restoring MCM5 expression can partially reverse ERβ knockdown-mediated growth reduction. Supportively, treating cells with the ERβ-specific antagonist, 4-[2-Phenyl-5,7-bis(trifluoromethyl) pyrazolo[1,5-a]pyrimidin-3-yl]phenol (PHTPP), reduced BCa cell growth and invasion, as well as MCM5 expression. Furthermore, we provide the first evidence that BCa burden and mortality can be controlled by PHTPP treatment in the carcinogen-induced BCa model. Together, these results demonstrate that ERβ could play positive roles in promoting BCa progression via MCM5 regulation. Targeting ERβ through ERβ-shRNA, PHTPP or via downstream targets, such as MCM5, could serve as potential therapeutic approaches to battle BCa.

[In situ diffuse reflectance FTIR spectroscopy study of CO adsorption on Ni2P/mesoporous molecule sieve catalysts].

PubMed

Liu, Qian-qian; Ji, Sheng-fu; Wu, Ping-yi; Hu, Lin-hua; Huang, Xiao-fan; Zhu, Ji-qin; Li, Cheng-yue

2009-05-01

Abstract The supported nickel phosphate precursors were prepared by incipient wetness impregnation using nickel nitrate as nickel source, diammonium hydrogen phosphate as phosphorus source, and MCM-41, MCM-48, SBA-15 and SBA-16 as supports, respectively. Then, the supported Ni2 P catalysts were prepared by temperature-programmed reduction in flowing Hz from their nickel phosphate precursors. The in situ diffuse reflectance FTIR spectroscopy (DRIFTS) analysis with the probe molecule CO was carried out to characterize the surface properties. The results indicated that there were significant differences in the spectral features of the samples. The upsilon(CO) absorbances observed for adsorbed CO on mesoporous molecule sieve was attributed to weak physical adsorption. There are four different kinds of upsilon(CO) absorbances observed for adsorbed CO on Ni2 P/MCM-41 catalyst with the following assignments: (1) the formation of Ni(CO)4 at 2055 cm(-1). (2) CO terminally bonded to cus Ni(delta+) (0

Stability of hemostatic proteins in canine fresh-frozen plasma thawed with a modified commercial microwave warmer or warm water bath.

PubMed

Pashmakova, Medora B; Barr, James W; Bishop, Micah A

2015-05-01

To compare stability of hemostatic proteins in canine fresh-frozen plasma (FFP) thawed with a modified commercial microwave warmer (MCM) or warm water bath (37°C; WWB) or at room temperature (22°C). Fresh-frozen plasma obtained from 8 canine donors of a commercial blood bank. A commercial microwave warmer was modified with a thermocouple to measure surface temperature of bags containing plasma. The MCM and a WWB were each used to concurrently thaw a 60-mL bag of plasma obtained from the same donor. Two 3-mL control aliquots of FFP from each donor were thawed to room temperature without use of a heating device. Concentrations of hemostatic proteins, albumin, and D-dimers; prothrombin time (PT); and activated partial thromboplastin time (aPTT) were determined for all samples. Significant decreases in concentrations of factors II, IX, X, XI, fibrinogen, von Willebrand factor, antithrombin, protein C, and albumin and significant increases in PT and aPTT were detected for plasma thawed with the MCM, compared with results for samples thawed with the WWB. Concentrations of factors VII, VIII, and XII were not significantly different between plasma thawed with the MCM and WWB. Concentrations of D-dimers were above the reference range for all thawed samples regardless of thawing method. No significant differences in factor concentrations were detected between control and WWB-thawed samples. Significant differences in hemostatic protein concentrations and coagulation times were detected for plasma thawed with an MCM but not between control and WWB-thawed samples. Clinical importance of these changes should be investigated.

A conserved modified wobble nucleoside (mcm5s2U) in lysyl-tRNA is required for viability in yeast

PubMed Central

Björk, Glenn R.; Huang, Bo; Persson, Olof P.; Byström, Anders S.

2007-01-01

Transfer RNAs specific for Gln, Lys, and Glu from all organisms (except Mycoplasma) and organelles have a 2-thiouridine derivative (xm5s2U) as wobble nucleoside. These tRNAs read the A- and G-ending codons in the split codon boxes His/Gln, Asn/Lys, and Asp/Glu. In eukaryotic cytoplasmic tRNAs the conserved constituent (xm5-) in position 5 of uridine is 5-methoxycarbonylmethyl (mcm5). A protein (Tuc1p) from yeast resembling the bacterial protein TtcA, which is required for the synthesis of 2-thiocytidine in position 32 of the tRNA, was shown instead to be required for the synthesis of 2-thiouridine in the wobble position (position 34). Apparently, an ancient member of the TtcA family has evolved to thiolate U34 in tRNAs of organisms from the domains Eukarya and Archaea. Deletion of the TUC1 gene together with a deletion of the ELP3 gene, which results in the lack of the mcm5 side chain, removes all modifications from the wobble uridine derivatives of the cytoplasmic tRNAs specific for Gln, Lys, and Glu, and is lethal to the cell. Since excess of the unmodified form of these three tRNAs rescued the double mutant elp3 tuc1, the primary function of mcm5s2U34 seems to be to improve the efficiency to read the cognate codons rather than to prevent mis-sense errors. Surprisingly, overexpression of the mcm5s2U-lacking tRNALys alone was sufficient to restore viability of the double mutant. PMID:17592039

Capacitive charge generation apparatus and method for testing circuits

DOEpatents

Cole, E.I. Jr.; Peterson, K.A.; Barton, D.L.

1998-07-14

An electron beam apparatus and method for testing a circuit are disclosed. The electron beam apparatus comprises an electron beam incident on an outer surface of an insulating layer overlying one or more electrical conductors of the circuit for generating a time varying or alternating current electrical potential on the surface; and a measurement unit connected to the circuit for measuring an electrical signal capacitively coupled to the electrical conductors to identify and map a conduction state of each of the electrical conductors, with or without an electrical bias signal being applied to the circuit. The electron beam apparatus can further include a secondary electron detector for forming a secondary electron image for registration with a map of the conduction state of the electrical conductors. The apparatus and method are useful for failure analysis or qualification testing to determine the presence of any open-circuits or short-circuits, and to verify the continuity or integrity of electrical conductors buried below an insulating layer thickness of 1-100 {micro}m or more without damaging or breaking down the insulating layer. The types of electrical circuits that can be tested include integrated circuits, multi-chip modules, printed circuit boards and flexible printed circuits. 7 figs.

Capacitive charge generation apparatus and method for testing circuits

DOEpatents

Cole, Jr., Edward I.; Peterson, Kenneth A.; Barton, Daniel L.

1998-01-01

An electron beam apparatus and method for testing a circuit. The electron beam apparatus comprises an electron beam incident on an outer surface of an insulating layer overlying one or more electrical conductors of the circuit for generating a time varying or alternating current electrical potential on the surface; and a measurement unit connected to the circuit for measuring an electrical signal capacitively coupled to the electrical conductors to identify and map a conduction state of each of the electrical conductors, with or without an electrical bias signal being applied to the circuit. The electron beam apparatus can further include a secondary electron detector for forming a secondary electron image for registration with a map of the conduction state of the electrical conductors. The apparatus and method are useful for failure analysis or qualification testing to determine the presence of any open-circuits or short-circuits, and to verify the continuity or integrity of electrical conductors buried below an insulating layer thickness of 1-100 .mu.m or more without damaging or breaking down the insulating layer. The types of electrical circuits that can be tested include integrated circuits, multi-chip modules, printed circuit boards and flexible printed circuits.

Micromechanical die attachment surcharge

DOEpatents

Filter, William F.; Hohimer, John P.

2002-01-01

An attachment structure is disclosed for attaching a die to a supporting substrate without the use of adhesives or solder. The attachment structure, which can be formed by micromachining, functions purely mechanically in utilizing a plurality of shaped pillars (e.g. round, square or polygonal and solid, hollow or slotted) that are formed on one of the die or supporting substrate and which can be urged into contact with various types of mating structures including other pillars, a deformable layer or a plurality of receptacles that are formed on the other of the die or supporting substrate, thereby forming a friction bond that holds the die to the supporting substrate. The attachment structure can further include an alignment structure for precise positioning of the die and supporting substrate to facilitate mounting the die to the supporting substrate. The attachment structure has applications for mounting semiconductor die containing a microelectromechanical (MEM) device, a microsensor or an integrated circuit (IC), and can be used to form a multichip module. The attachment structure is particularly useful for mounting die containing released MEM devices since these devices are fragile and can otherwise be damaged or degraded by adhesive or solder mounting.

Unconscious mood-congruent memory bias in depression.

PubMed

Watkins, P C; Vache, K; Verney, S P; Muller, S; Mathews, A

1996-02-01

The purpose of this study was to investigate an unconscious or implicit mood-congruent memory (MCM) bias in clinical depression. Many studies have shown an explicit memory bias, but no study has yet found an implicit MCM bias in clinical depression. The authors compared depressed and control group participants on a conceptually driven implicit memory test. After studying words of positive, neutral, and negative affective valences, participants produced free associations to various cues. Implicit memory or priming was demonstrated by the production of more studied than unstudied words to the association cues. Depressed participants showed more priming of negative words, whereas controls showed more priming of positive words, thus supporting the MCM pattern. Also, no implicit memory deficit was found in depressed participants. These findings are discussed in the context of several prominent theories of cognition and depression.

Assembling photoluminescent tri(8-quinolinolato)aluminum into periodic mesoporous organosilicas.

PubMed

Yang, Ying; Zhang, Xin; Kan, Qiubin

2013-12-01

Mesostructured and mesoporous materials are emerging as a new class of optical materials. However, their synthesis is nontrivial. In this work, periodic mesostructured metal complex-containing silicas of MCM- and SBA-type bearing homogeneously distributed photoluminescent tri(8-quinolinolato)aluminum inside the channel walls (denoted as Alq3@PMO-MCM and Alq3@PMO-SBA, respectively) have been achieved via one-pot co-assembling of inorganic/surfactant/optically active species. A comprehensive multianalytical characterization of the structural and optical properties demonstrates that both Alq3@PMO-MCM and Alq3@PMO-SBA series gainfully combine the photoluminescent properties of Alq3 with the porous features of PMOs. Regularly arranged pores provide high surface area to disperse optically active components well and render Alq3-containing PMOs promising materials for optoelectronic applications. Copyright © 2013. Published by Elsevier Inc.

Bromocresol Green/Mesoporous Silica Adsorbent for Ammonia Gas Sensing via an Optical Sensing Instrument

PubMed Central

Chang, Yu-Chang; Bai, Hsunling; Li, Shou-Nan; Kuo, Chun-Nan

2011-01-01

A meso-structured Al-MCM-41 material was impregnated with bromocresol green (BG) dye and then incorporated into a UV-Vis DRA spectroscopic instrument for the online detection of ammonia gas. The absorption response of the Al-MCM-41/BG ammonia sensing material was very sensitive at the optical absorption wavelength of 630 nm. A high linear correlation was achieved for ppmv and sub-ppmv levels of ammonia gas. The response time for the quantitative detection of ammonia gas concentrations ranging from 0.25 to 2.0 ppmv was only a few minutes. The lower detection limit achieved was 0.185 ppmv. The color change process was fully reversible during tens of cycling tests. These features together make this mesoporous Al-MCM-41 material very promising for optical sensing applications. PMID:22163836

Development of beam leaded low power logic circuits

NASA Technical Reports Server (NTRS)

Smith, B. W.; Malone, F.

1972-01-01

The technologies of low power TTL and beam lead processing were merged into a single product family. This family offers the power and thermal advantages of low power(54L), while providing the additional reliability advantages of beam leads. The reduction in the power and heat levels also allows the system designer to take advantage, through beam lead, multichip assemblies, of increased package density to reduce system size and weight.

Panoramic Images Mapping Tools Integrated Within the ESRI ArcGIS Software

NASA Astrophysics Data System (ADS)

Guo, Jiao; Zhong, Ruofei; Zeng, Fanyang

2014-03-01

There is a general study on panoramic images which are presented along with appearance of the Google street map. Despite 360 degree viewing of street, we can realize more applications over panoramic images. This paper developed a toolkits plugged in ArcGIS, which can view panoramic photographs at street level directly from ArcMap and measure and capture all visible elements as frontages, trees and bridges. We use a series of panoramic images adjoined with absolute coordinate through GPS and IMU. There are two methods in this paper to measure object from these panoramic images: one is to intersect object position through a stereogram; the other one is multichip matching involved more than three images which all cover the object. While someone wants to measure objects from these panoramic images, each two panoramic images which both contain the object can be chosen to display on ArcMap. Then we calculate correlation coefficient of the two chosen panoramic images so as to calculate the coordinate of object. Our study test different patterns of panoramic pairs and compare the results of measurement to the real value of objects so as to offer the best choosing suggestion. The article has mainly elaborated the principles of calculating correlation coefficient and multichip matching.

Synthesis of an Ionic Liquid and Its Application as Template for the Preparation of Mesoporous Material MCM-41: A Comprehensive Experiment for Undergraduate Students

ERIC Educational Resources Information Center

Hu, Jun; Yin, Jinxiang; Lin, Tianshu; Li, Guangtao

2012-01-01

A new solvent-free microwave experiment to synthesize the ionic liquid 1-hexadecyl-3-methylimidazolium bromide (HDMIm-Br) in high yield is presented. The structure is confirmed by IR and [superscript 1]H NMR spectra. HDMIm-Br is then used to prepare an organic-inorganic mesoporous material MCM-41. The microscopic arrangements of mesoporous…

Cu(OAc)2/MCM-41: an efficient and solid acid catalyst for synthesis of 2-arylbenzothiazoles under ultrasound irradiation.

PubMed

Sadjadi, Sodeh; Sepehrian, Hamid

2011-03-01

A new, convenient method for the syntheses of 2-arylbenzothiazoles is described in the presence of catalytic amounts of Cu(OAc)(2)/MCM-41 under ultrasonic irradiation. Short reaction times, easy and quick isolation of the products, reusability of the catalyst and excellent yields are the main advantages of this procedure. Copyright © 2010 Elsevier B.V. All rights reserved.

Maintaining Genome Stability: The Role of Helicases and Deaminases

DTIC Science & Technology

2006-07-01

functional for replication. Then, we screened the surviving transformants for sensitivity to hydroxyurea . Our first screen was conducted under conditions...that are lethal for checkpoint mutants such as ∆rad3. We did not observe any hydroxyurea -sensitive MCM clones. However, following the old genetics...this kinase. In particular, we observe that an mcm4ts mutant blocked in hydroxyurea , and then released to restrictive temperature, is competent to