Search Results - (Author, Cooperation:L. J. Lee)

2012-12-22

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

*Alternative Splicing ; Animals ; Biological Evolution ; Chickens/genetics ; *Evolution, Molecular ; Exons ; Introns ; Lizards/genetics ; Mice/genetics ; Mice, Inbred C57BL/genetics ; Opossums/genetics ; Phenotype ; Platypus/genetics ; Primates/genetics ; RNA Splice Sites ; Regulatory Sequences, Ribonucleic Acid ; Species Specificity ; *Transcriptome ; Vertebrates/*genetics ; Xenopus/genetics

2014-12-20

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Adaptor Proteins, Signal Transducing/genetics ; *Artificial Intelligence ; Child Development Disorders, Pervasive/*genetics ; Colorectal Neoplasms, Hereditary Nonpolyposis/*genetics ; Computer Simulation ; DNA/genetics ; Exons/genetics ; Genetic Code ; Genetic Markers ; Genetic Variation ; Genome-Wide Association Study/*methods ; Humans ; Introns/genetics ; Models, Genetic ; Molecular Sequence Annotation/*methods ; Muscular Atrophy, Spinal/*genetics ; Mutation, Missense ; Nuclear Proteins/genetics ; Polymorphism, Single Nucleotide ; Quantitative Trait Loci ; RNA Splice Sites/genetics ; RNA Splicing/*genetics ; RNA-Binding Proteins/genetics

2018-03-06

Rockefeller University Press

0022-1007

1540-9538

Medicine

2018-04-17

Institute of Physics (IOP)

1757-8981

1757-899X

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

2018-03-09

American Association for the Advancement of Science (AAAS)

2375-2548

Natural Sciences in General

2018-02-09

BMJ Publishing

2044-6055

Medicine

Open access, Paediatrics

2018-02-16

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Geosciences

Computer Science

Medicine

Natural Sciences in General

Physics

Atmospheric Science, Science and Policy

2018-12-07

Genetics Society of America (GSA)

0016-6731

Biology

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

We describe the construction of a high voltage electric arc puller for controllable fabrication of bent near-field optical fiber probes. Various probes with bent angles ranging from 30° to 75° and bent lengths between 600 and 900 μm were successfully produced. The tip diameters achieved are between 100 and 200 nm. These bent type probes can be made into cantilevered probes that can be used for any dynamic mode atomic force microscope, and make the construction of a scanning near-field optical microscope easily attainable.© 1998 American Institute of Physics.

Electronic Resource

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

We present the modification of a commercial tapping mode atomic force microscope into a reflection and transmission dual mode scanning near-field optical microscope. In the configuration, the normal force detection unit is replaced by a shear force detection module and an interfacing circuit. The tip-sample distance control is therefore similar to tapping mode operation. Detection of the near-field signals is based on photodiodes and the lock-in technique, and the resolutions obtained for the topography and the near-field signal are around 80 and 150 nm, respectively.© 1998 American Institute of Physics.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

High quality in situ boron doped polycrystalline diamond films were grown on the scratched Si (100) substrate. A saturated deionized water solution of boron acid was chosen as a dopant source. The concentration profiles of boron, tantalum, and oxygen were examined by using scanning Auger nanoprobe and secondary ion mass spectroscopy. The boron atoms are uniformly distributed inside each diamond grain. However, no Auger signal from boron was observed at grain boundaries within the detection limit. In contrast, tantalum atoms are uniformly distributed across diamond grains and grain boundaries. A simple model was proposed in explaining the boron desegregation. © 1995 American Institute of Physics.

Electronic Resource

0005-2744

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Electronic Resource

0032-3888

Chemistry ; Chemical Engineering

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Physics

A free radical copolymerization model is proposed for simulating the reaction rates and conversions of styrene monomer and unsaturated polyester resins during curing. This model is based on film theory in which the rate constants reflect both reaction and diffusion resistances. Differential scanning calorimetry in combination with Fourier transform infrared spectroscopy is used to measure the overall and individual reactivities of reacting species. Model parameters are determined from experimental data. The applicability of this model is demonstrated in a cure simulation.

6 Ill.

Electronic Resource

0001-1541

Chemistry ; Chemical Engineering

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Process Engineering, Biotechnology, Nutrition Technology

A kinetic model has been developed for radical chain growth type of reactive polymer processing operations. This model incorporates considerations of the molecular diffusion that is described by a free volume theory and the basic reaction mechanism of the free-radical chain polymerization. Experimental results from the bulk styrene polymerization and a reaction of sheet molding compound (SMC) showed good agreement with the model.

12 Ill.

Electronic Resource

0032-3888

Chemistry ; Chemical Engineering

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Physics

The analytical flow model developed in Part I was applied to the online control of profile extrusion. A rubberized polystyrene was extruded through a simple L-shaped profile die with one thin section and one thick section. Take-up speed was used to control the size of the extrudate, and die temperature was used to control the shape of the extrudate. Two different control algorithms, a dual single-loop feedback PI controller and a multivariable feedforward plus feedback control method (FFC), were carried out for set point changes of the extrudate shape and size, and load disturbances of screw speed. Results showed that the PI feedback controller was satisfactory for long-term set point changes but not for load changes. The FFC worked well for load disturbances lower than 10 cycles/min. Owing to the slow dynamic response of die temperature, the shape loop can only be controlled for long-term disturbances.

14 Ill.

Electronic Resource

0032-3888

Chemistry ; Chemical Engineering

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Physics

Summarized in this paper are the experimental results and mathematical modeling of processing of polyureas. The experimental part includes the applications of solution polymerization to study the reaction kinetics of polyureas. The theoretical part includes a kinetic and heat transfer model that can apply solution polymerization data to predict the bulk polymerization of polyurea in the reaction injection molding process.

15 Ill.

Electronic Resource

0032-3888

Chemistry ; Chemical Engineering

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Physics

In this study, an interpenetrating polymer network (IPN) based on a polyurethane (PU) and a partially end-capped unsaturated polyester (UPE) was prepared. The reaction-induced phase separation process of the IPN was studied using a phase contrast optical microscope and a transmission electron microscope (TEM), while reaction kinetics and onset of gelation were determined by a differential scanning calorimeter and a rheometer respectively. Except at low temperatures, the phase separation patterns were found to follow the spinodal decomposition mechanism. An interconnected phase developed quickly and was followed by coalescence of the periodic phase to form droplet/matrix type of morphology. A second level of phase separation also occurred within both the droplet and the matrix phases in some cases. The domain sizes resulting from both levels of phase separation gradually increased until the structure was locked by chemical gelation. Reaction temperature, PU reaction rate, and UPE reaction rate all had significant effects on the final morphology of the formed IPNs.

14 Ill.

Electronic Resource

0032-3888

Chemistry ; Chemical Engineering

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Physics

Interpenetrating polymer networks (IPNs) based on a polyurethane (PU) and two unsaturated polyester (UPE) resins (a commercially available UPE and a partially endcapped UPE) were prepared. The mechanical properties, such as tensile strength, elongation at break, impact strength, and dynamic mechnical properties of IPNs, were studied by changing reaction temperature, PU reaction rate, and UPE reaction rate. Owing to the unique microgel formaton of UPE, the first formed network tends t be the dispersed phase in the PU-UPE IPN system. The reaction sequence was found to be an important factor in determining the phase mixing and phase morphology of the IPNs. When the PU reaction was faster, extensive phase mixing due to strong grafting or chain interpenetration was obtained. When the UPE reacted first, grafting was retarded by the microgel formation of the UPE network. It was found that simultaneous reaction of the two reacting system resulted in a co-continuous structure that provided enhanced tensile properties and impact strength.

15 Ill.

Electronic Resource

0032-3888

Chemistry ; Chemical Engineering

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Physics

The development of molecular orientation and internal stresses in extruded sheet made of polypropylene was analyzed, and their correlations to operating conditions such as draw ratio, cooling rate, die temperature, melt temperature, and die gap opening were studied. Measurements of attenuated-total-reflectance infrared dichroic ratio for the surface molecular orientation, birefringence for the orientation stress distribution in the thickness direction, and free shrinkage ratio for the overall frozen-in stresses were carried out to determine the amount of orientation stresses in the extruded samples. As expected, the overall orientation stress depends strongly on draw ratio, while higher melt temperature reduces the overall orientation. It was found that faster cooling rates and lower die temperatures cause surface orientation stresses to increase as the core orientation stresses remain almost unchanged.

9 Ill.

Electronic Resource

0032-3888

Chemistry ; Chemical Engineering

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Physics

An analytical model based on the heat penetration through the die wall was preposed to calculate the effect of die wall temperature on the flow of polymer melt in profile dies. Model prediction matched well with the experimental data measured from a modified Instron capillary rheometer. The model was applied to an extrusion line with an L-shaped profile die. Dynamic responses of the profile extrusion line based on this die were measured and modeled. The pairing of manipulated variables and controlled variables was analyzed.

12 Ill.

Electronic Resource