bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimizing Geotechnical Parameters for Sustainable Road Embankments in Flood Disaster-Prone Areas of Bangladesh
Authors: Sarker Sree Pradip Kumer , Islam Md. Maminul
Published: January 2024

The vulnerability of transportation infrastructure to flood disasters in Bangladesh necessitates strategic interventions to optimize geotechnical parameters for sustainable road embankments. This study focuses on a flood disaster-prone region of Bangladesh, aiming to enhance the resilience and sustainability of road infrastructure in the face of recurring floods. The research is driven by the imperative to develop effective engineering strategies that mitigate the impact of floods on road embankments, ensuring safe and reliable transportation networks. The study area is characterized by a complex interplay of geographic and geological factors that contribute to its susceptibility to flooding. Understanding the local geology is crucial for tailoring geotechnical parameters to the specific conditions of the region. Detailed analyses of soil types, their composition, and formation processes provide the foundation for the subsequent optimization efforts. The methodology employed involves systematic sampling along a Road, incorporating both in-situ and laboratory testing. Geotechnical analyses include the evaluation of critical parameters such as California Bearing Ratio (CBR), shear strength, and soil composition. These analyses are instrumental in identifying key geotechnical characteristics that significantly influence the performance of road embankments during flood events. The optimization process encompasses the application of advanced techniques to enhance the resilience of road embankments. The results and subsequent discussions delve into the effectiveness of the optimization strategies in comparison to existing standards and guidelines for road construction. This involves a comprehensive assessment of soil properties, composition, and the outcomes of the optimization process. Finally, the study sheds light on the critical role of geotechnical parameters in developing sustainable road embankments in flood-prone areas. The findings not only contribute to the understanding of the study area but also offer valuable insights for broader applications in flood disaster mitigation in Bangladesh. The research emphasizes the need for a proactive approach to optimize geotechnical parameters, paving the way for resilient and sustainable road infrastructure that can withstand the challenges posed by recurrent floods.
Khuzāma (Lavandula angustifolia Mill.): Pharmacological Action and Therapeutic Uses in Perspective of Unani Medicine: A Review
Authors: Kalam Mohd Afsahul , Habib Abdul , Arzoo Khan Sabiha , Ahmad Wasim , Ahmad Riyaz , Avid Mohammad
Published: January 2024

Lavandula angustifolia Mill., commonly known as lavender, is a highly regarded medicinal herb in Unani Medicine. Its aerial parts, including leaves and flowers, are utilized for their therapeutic properties, and the plant is a common ingredient in cosmetic products. The essential oil derived from lavender is known for its sedative, carminative, anti-depressive, anti-inflammatory, and antimicrobial properties. These pharmacological effects are attributed to various bioactive compounds like betulin, betulinic acid, lactone, 3 beta-formyl ursolic acid, essential oil, glycolic acid, valeric acid, and linalyl acetate. This review aims to comprehensively explore Lavandula angustifolia Mill., covering identification, pharmacological actions, traditional uses, and recent scientific investigations. Utilizing a diverse range of sources, including scientific literature and research studies, the review adopts a comprehensive approach to compile information. The diverse array of bioactive constituents in lavender contributes to its medicinal profile, making it a versatile herbal remedy. Emphasis is placed on documenting and highlighting various pharmacological activities, reinforcing lavender's status as a potent therapeutic agent. Beyond its medicinal applications, the review delves into lavender's historical uses in Unani Medicine and its contemporary role in cosmetic formulations. Lavandula angustifolia Mill. emerges as a herbal powerhouse, offering a holistic approach to health and well-being. This review serves as a valuable resource for practitioners of traditional medicine and modern science alike, bridging the gap between historical wisdom and contemporary research in the realm of herbal medicine.
Gene Therapy, Ethics, Germ Cell Gene Transfer
Authors: Nelson Robert
Published: October 2003

Introduction

Discussion Overview

Technical Issues with GCGT

Ethics of GCGT Research

Major Objections to GCGT

Eugenics and the Desire to Prevent Genetic Disease

Treatment and Enhancement: A Role for Positive Eugenics

The Analogy Between Pre‐Embryo Discard and Abortion

Alternatives to GCGT

GCGT in the Treatment of Mitochondrial Disease

The Social and Political Control of Genetic Technology
Strategic Alliances and Technology Licensing in Biotechnology
Authors: Lerner Josh
Published: October 2003

Introduction

Why are Alliances and Licensing So Important in Biotechnology?

How are Alliances Structured?

What is the Evidence from Field Research?

Where is Further Research Needed?
Media Coverage of Biotechnology
Authors: Nelkin Dorothy
Published: October 2003

Introduction

Historical Overview

Interferon

Promises of Gene Therapy

Cloning

Genetics of Human Behavior

The Reporting on Biotechnology Risk
Reproduction, Law, Wrongful Birth, and Wrongful Life Actions
Authors: Botkin Jeffrey R.
Published: October 2003

Introduction

Clinical Circumstances Giving Rise to Wrongful Life and Wrongful Birth Claims

Legal History of Wrongful Life

Legal History of Wrongful Birth

Philosophical and Public Policy Issues
Human Subjects Research, Ethics, Compensation of Subjects for Injury
Authors: Ackerman Terrence F.
Published: October 2003

Introduction

Some Initial Distinctions

History of the Compensation Debate

Moral Basis of Compensation

Extent of Research Injuries

Elements of a Compensation Program
Reproduction, Ethics, Sex Selection
Authors: LeRoy Bonnie S. , Bartels Dianne M.
Published: October 2003

Introduction

Background

Sperm Separation

Preimplantation Diagnosis

Fetal Sex Determination

Attitudes Toward Sex Selection

Case Study

Ethical Arguments for and Against Sex Selection
Genetic Information, Ethics, Privacy and Confidentiality: Overview
Authors: Powers Madison
Published: October 2003

Introduction

Privacy, Confidentiality, and Anonymity

Uniqueness of Genetic Information

Research Contexts

Confidentiality in Clinical Contexts

Nonmedical Uses of Genetic Information
Agricultural Biotechnology, Socioeconomic Issues, and the Fourth Criterion
Authors: Lacy William
Published: October 2003

Introduction

The Fourth Criterion

Farmers, Rural Communities, and the Food System

Agribusiness and Industry

Consumers

Science and Technology Transfer

Developing Countries and the Global Economy

Strategies for Incorporating the Fourth Criterion
Professional Power and the Cultural Meanings of Biotechnology
Authors: Nelson Robert M. , Brodwin Paul
Published: October 2003

Introduction

Prolonged Ventilation for Children with Neuromuscular Disease

Meaning of Tears

Knowledge and Communication

Knowledge and Power

Difference Between Starting and Stopping

Is Technology Value‐Neutral?

Contesting Power Over Technology

Boundary of Body

Concluding Remarks
Federal Policy Making for Biotechnology Executive Branch Office of Management and Budget
Authors: Omenn Gilbert S.
Published: October 2003

Introduction

OMB Role in Biotechnology

Budget Initiative and Analysis

Budget Follow‐on to the Budget Initiative
Recombinant
DNA
, Policy,
A
silomar Conference
Authors: Weiner Charles
Published: October 2003

Introduction

Scientists' Original Concern About Hazards

The Berg Committee Letter

The 1975 Asilomar Conference

Recombinant DNA Advisory Committee

Local and National Political Responses

Evolution of Research Guidelines

Beginnings of Commercialization

Environmental Release of Modified Organisms

Human Gene Transfer Experiments

Limitations of Self‐Regulation
Academic Industry Relationships in Biotechnology, Overview
Authors: Blumenthal David , Campbell Eric G.
Published: October 2003

Introduction

Recent History of AIRs in Biotechnology

Definitions of AIRs in Biotechnology

Prevalence and Magnitude of AIRs

Benefits of AIRRs

Risks of AIRRs

AIRRs in Genetics (A Special Case)

AIRRs in Biotechnology, 1985–1995

Implications for Policy and Management
Medical Biotechnology,UnitedStates Policies Influencing its Development
Authors: Cook‐deegan Robert Mullan
Published: October 2003

Introduction

Definitions

Factors Affecting the Commercial Development of Biotechnology

Capital Availability

Funding for Research and Development

Patents

University–Industry Relations

Regulation of Products and Services

Public Perception and Political Process
International Aspects: National Profiles,
J
apan
Authors: Macer Darryl R.J.
Published: October 2003

Introduction

Genetic Engineering and Biotechnology in Japan

Public Acceptance of Biotechnology

Japanese Law and Biotechnology

Japanese Culture, Biotechnology, and Bioethics

The Future and Trust
Patents and Licensing, Policy, Patenting of Inventions Developed with Public Funds
Authors: Katz Dana , Merz Jon F.
Published: October 2003

Introduction

Early Innovation

Historical Milestones

Industrialization

Bureaucratization

Development of Technology Transfer

Publicly Funded Research and Biotechnology
Federal Policy Making for Biotechnology, Executive Branch,
RAC
Authors: Walters LeRoy
Published: October 2003

Early History and Work of RAC, 1974 to 1983 and 1984 to 1990

Parallel Efforts by NIH and FDA, 1991 to 1995

Verma Committee Report and Orkin‐Motulsky Committee Report, September 1995 and December 1995

Eighteen Months of Uncertainty, May 1996 to October 1997

From October 1997 to the Present: How is the New System Working?
Human Operations in Space During the Space Shuttle Era
Authors: Hawley Steven A.
Published: October 2003

When the Space Shuttle Columbia was launched on its maiden flight 20 years and more than 100 flights ago, it carried a crew of two, an instrumentation pallet as its only payload, and the key mission objectives were to see if launch and landing could be performed safely. That launch also carried the promise of a new era of space operations, including research in space, launching and retrieving of satellites, in‐orbit maintenance of spacecraft, and ultimately the building and use of a space station. Slowly and deliberately during these 20 years, the flight team on the ground and in orbit has developed the maturity of operations in space and the goal of achieving complex operations with humans from the Space Shuttle. This article looks back at the last 20 years of Space Shuttle operations to review what has been accomplished in attaining these objectives. The goal of this review is not to serve as a chronology of all 100 flights, but rather to highlight some of the key milestones in developing the sophisticated level of human operations in space that is possible today.

On NASA promotional material published before STS‐1 highlights one of the claims made for the Space Shuttle before its first mission: “Shuttle crews will be able to retrieve satellites from Earth orbit and repair and redeploy them or bring them back to Earth for refurbishment and reuse. The Shuttle can be used to carry out missions in which scientists and technicians conduct experiments in Earth orbit or service automated satellites already orbiting.”

The key design characteristics of the Space Shuttle that made these claims possible 20 years ago included a heavy lift launch capability, a large payload bay, a robotic arm, the ability to carry a sizable crew, development of routine extravehicular activity (EVA) capability, and reusability of most key system components. Methodically, step‐by‐step during the last two decades, the ability of humans to work in space was expanded, increasingly more complex tasks were undertaken, and more and more of the resources of the crew and Shuttle were devoted to accomplishing the mission objectives.

Neither large flight rate nor vehicle autonomy has been achieved. In fact, the greatest number of flights flown in one calendar year was eight and, although mission control has been streamlined since STS‐1, particularly by using modern software applications and workstations, the issue of the appropriate division of labor between the ground and the flight crew is still debated today. Nevertheless, the vision of the Shuttle as a versatile platform for humans, hardware, and associated space operations was realized very much as advertised 20 years ago. This article concludes with a discussion of the assembly of the
International Space Station
and what type of vehicle should replace the shuttle.
Extraterrestrial Life, Searching for
Authors: Tarter Jill
Published: October 2003

Since at least the beginning of recorded history, humans have looked up at the sky and wondered whether or not we are alone. Traditionally, we have consulted philosophers and religious figures for guidance in answering this question. In every age and in every culture, these leaders have responded according to the particular belief system that they embraced at the time. Today, we live in a very special time. Beginning at the end of the twentieth century, humans acquired the knowledge and technological capability to try to answer this old and important question by doing experiments. As we begin the twenty‐first century, scientists and the engineers may, in the near future, be able to present us with the first examples of life off planet Earth. At one extreme, we may be able to discern at a distance only some very suggestive biomarkers, without knowing whether they reveal the presence of microbes or minds. At the other extreme, it may be possible to discover another technologically advanced civilization and engage in some form of communication with it. In the middle ground, we may be able to acquire actual samples of biology from another world within our solar system and by returning them to our labs, unambiguously determine whether they represent an independent genesis of life. Or, to the contrary, whether all life on Earth can be traced to a distant place of origin.

Within this century, perhaps within our own lifetimes, we may know whether the laws of physics and chemistry, operating throughout the universe, routinely produce biology.

Liquid water is the key to all life as we know it. Water chauvinism will inevitably guide (and even bias) our search for habitable domains and life off Earth.

This article discusses the various searches for inhabited/inhabutable planets. The SETI project (search for extraterrestrial intelligence today and its future are discussed). SETI tomorrow is also explored as is what to do if the search succeeded. Who will speak for earth and what they will say rounds out the discussion.
Size and Shape of Earth from Satellites
Authors: Schutz B.E.
Published: October 2003

Modern evidence abounds that clearly supports the idea that Earth is a spherical body. The memorable photographs of Earth taken by the Apollo astronauts from the lunar surface and from cislunar space must motivate serious consideration of the sphericity notion even among the hardest skeptic.

But the stirring evidence presented in a photograph from space was unavailable to the ancients who had to deduce the ideas of sphericity from subtle effects (such as the sails of a ship slowly sinking at the horizon), from obvious comparative forms (the Moon and Sun appear to be spheres), and from philosophical ideas (the sphere is a perfect geometric object, hence Earth must be a sphere). Although these early approaches spurred the development of the science of geodesy, the revolutionary work of Isaac Newton in the seventeenth century brought the first renaissance in geodesy. The second renaissance coincides with the space age, which brought new tools to the pursuit of ancient questions. The new discipline of space geodesy appeared in the early 1960s, but the areas of geodetic interest go far beyond the classical study that focused on the size and shape of Earth. Modern geodesy includes scholarly pursuits into the mass distribution within Earth, as manifested by the external gravity field, the rotation of Earth, and temporal changes in the positions of points on Earth's surface. The modern tools and techniques of geodesy are used by other scientific disciplines, including tectonophysics, oceanography, and glaciology, to name a few. And the methodologies and concepts are applied to other planets in the discipline known as planetary geodesy. This article gives the history of the various periods and ends with a discussion of using satellites and computers to describe the Earth's shape
Communications Satellites, Technology of
Authors: Dorfman Steven D.
Published: October 2003

In 1895, a Russian scientist, Konstantin Tsiolkovsky, gave the world its first vision of a stationary satellite. He observed that an object orbiting Earth at 22,300 miles up would match the angular rotation of Earth and thus provide a seemingly stationary “star” overhead.

Fifty years later, Arthur C. Clarke expanded on this vision. In 1945, he indicated that such an object orbiting Earth at 22,300 miles up must also have its orbit in the equatorial plane to be considered stationary. Clarke called the object a “satellite” and further noted that providing a satellite in this orbit with a communications repeater could produce a very valuable communications capability. Clarke named such satellites “geostationary communication satellites.” Clarke postulated that three geostationary satellites spaced 120° apart would provide full global communications coverage for telephone and television service to the world's population.

Clarke's concept was ahead of the technologies needed to make it a reality. This article gives the history of communication satellites. In a few decades, communications satellites have become an indispensable part of the world’s communications infrastructure Orbits, communication links, on‐board antennas, ground antennas are discussed. Communication satellites have two different designs: spinner and body‐stabilized satellites new technology in digitization, power, propulsion, and systems are introduced.
Biomedical Support of Piloted Spaceflight
Authors: Grigoriev A.I. , Malashenkov D.K.
Published: October 2003

Recent progress in the conquest of space and in piloted cosmonautics is the result of developments in space technology and hardware and, to a significant extent, has also depended on the solution of complex biomedical problems and other achievements in space biology and space medicine. During the period under discussion, the duration of space flight has increased to 14.5 months for men and 6 months for women. The long period during which the Mir orbital station was used (15 years) has generated unique experience in solving biomedical problems to ensure the safety and efficiency of increasingly long spaceflights.

Space medicine is basically a type of prophylactic medicine. Its duties include predicting all of the physiological consequences of exposure to spaceflight factors and preventing or curtailing likely disruptions in the functioning of various systems.

Support of piloted spaceflights involves a complex set of biomedical, technical, and organizational measures directed at creating the conditions required if normal human vital processes are to occur in space and using special means and methods to maintain cosmonaut health and performance at the level needed to ensure completing the standard flight program and for high crew efficiency if contingency or emergency situations occur.

Many years of research conducted by the Institute of Biomedical Problems jointly with a number of other organizations (see section on

) has resulted in creating an efficient biomedical piloted spaceflight support system. This system is discussed in this article. The overall program of measures performed by personnel working in space medicine is very extensive and includes three phases: preflight, in‐flight and postflight.
Conversion of Missiles into Space Launch Vehicles
Authors: Konyukhov Stanislav Nikolaevich
Published: October 2003

This article begins with a brief history of the Yuzhnoe Design Bureau, one of the leading design bureaus in the Soviet Union and Ukraine. The Yuzhnoe Design Bureau designed numerous strategic missile systems, launch vehicles, and spacecraft. One interesting aspect of this history involves the conversion of missiles into space launch vehicles by a team of developers led by the Yuzhnoe Design Bureau, well in advance of the officially announced USSR conversion effort. The history of the design bureau is given. Details of the various genarations of missle systems and launch vehicles are given. The final discussion is about the Dneper launch vehicle based on a decommissioned 15A18 missile.
Eastern Launch Facilities, Kennedy Space Center
Authors: Neilon John J.
Published: October 2003

The Eastern Test Range (ETR) is the familiar designation of a group
of bases, facilities, and installations that support space vehicle launches
from Cape Canaveral Air Station (CCAS) and the Kennedy Space Center (KSC) and
ballistic missile test launches from or near the Cape Canaveral Air Station. It
is operated by the United States Air Force's 45th Space Wing, which
provides services to itself as a launch agency as well as to the other
Government and private agencies that use the launch bases at Cape Canaveral and
KSC. The ETR, or “The Range” as it is often called, extends from
the Atlantic Coast of central Florida, including the well‐known Cape
Canaveral launch base and its Headquarters about 20 miles south at Patrick Air
Force Base, southeast along the Bahamas, the West Indies, and on to Ascension
Island in the South Atlantic Ocean. Recently, bases in Bermuda and Newfoundland
have been added to support launches that have more northerly azimuths.

This article gives details on the Eastern Range facilities: the
missile assembly buildings, propellant storage, control center, skid skip,
tracking stations, range support, safety, and instrumentation.

The Kennedy Space Center and the various missions launched from the
center are discussed. Apollo operations, Skylab, Space Shuttle,
Apollo‐Soyuz Test Program, and the International Space Station are
detailed.

The article concludes with NASA's requirements to keep the
public informed of its activities and the ways NASA accommodates visitors to
the Space Center.
Cosmonauts Selection and Preparation
Authors: Egorov Alexander N. , Sosyurka Yu.B. , Yaropolov V.I.
Published: October 2003

The Soviet Union's launch of the world's first artificial Earth satellite on 4 October 1957 and its subsequent achievements in developing rockets and space technology and flying living beings in its space flight program marked the beginning of preparations for the first human spaceflight. The issue of human spaceflight was discussed in the USSR Academy of Sciences as early as the very beginning of 1959.

Selection of the first cosmonauts began in October 1959 among men in Air Force units. It was believed that the best candidates for the first piloted spaceflight would come from the ranks of military pilots. Documents for more than 3000 fighter pilots, aged 35 or below, were examined to select the first cosmonaut candidates. Only 29 pilots passed all phases of medical selection and, of these, 20 were accepted into the spaceflight training program (subsequently, requirements for cosmonaut health standards were relaxed somewhat).

The first group of cosmonauts trained at the Cosmonaut Training Center included Yu.A. Gagarin, who completed an orbital flight of 1 hour 48 minutes on the Vostok‐1 piloted spacecraft on 12 April 1961. After Gagarin's flight, G.S. Titov was trained to perform a 1‐day space flight. This flight was completed in August 1961. The next phase of the Center's activity focused on training cosmonauts for group flights. Subsequently, the Center entered a phase in which cosmonauts were trained for flights on the multiman piloted spacecraft of the Voskhod series, which had just been developed. Training these crews emphasized the use of the new capabilities these spacecraft had for conducting scientific, technological, and biomedical experiments and enabling extravehicular activity.

In 1966 Center specialists began to train cosmonauts in a program involving testing and a series of flights on the new multiperson, multipurpose piloted spacecraft of the Soyuz series, which possessed technical capacities that significantly exceeded those of Vostok.

This article gives the history of the various training programs implemented at the Center. Programs included training for lunar landings, the Almaz space station and the Salyut 4 long‐term space station. The Center is now participating in the training of astronauts and cosmonauts to support the International Space Station.

As space technology developed, the goals, structure, and technical facilities underwent change. The main activities of the Center are given in detail.
Mars
Authors: Considine Glenn D.
Published: October 2003

The fourth planet from the Sun, Mars is the first planet in the solar system beyond Earth. Compared with Earth, Mars is a small planet. With a value of 1.00 for Earth, the mass of Mars is 0.107; the density, 0.719; volume, 0.149. The equatorial diameter of Mars is 4,226 miles (6,772 kilometers) as compared with that of earth of 7,960 miles (12,757 kilometers). Although Mars has been observed since early times, reliable and detailed data did not become available until commencement of theMarinerexploratory program in the 1960's. With theVikingprograms of the last half of the 1970s, some importantMarinerdata had to be revised

Mars has two satellites, or moons, Phobos and Deimos, both discovered in 1877 by Hall. Spacecraft have shown these bodies to be cratered, rocky, and chunky, and in recent years there has been serious speculation that these may not be moons in the usual sense, but rather captive asteroids. (See also Asteroids.) Phobos is quite small, with dimensions of approximately 12.4×17.4 miles (20×28 kilometers) and Deimos even smaller, 6.2×9.9 miles (10×16 kilometers). These satellites were visited during theVikingmissions.

The twinVikingmissions to Mars, each with its own lander, represented a very sophisticated and successful venture. Among some scientists there remains perplexity regarding some of the main features of the planet, notably numerous channels and rifts at one time called “canals” by Earth‐bound observers several decades ago. Knowledge of how these features look (including full‐color) and their dimensions have been greatly enhanced, but the mysteries of their origins remains unknown. Earth‐bound estimates andMariner'smeasurements of Mars comparatively thin atmosphere were confirmed, a factor which detracted from the possibility of organisms living on the planet. The polar ice cap once thought to be frozen carbon dioxide has been found to be ice with possibly some frozen carbon dioxide with it other findings related to weather, age of Mars, and volcanisms are discussed. Biological experiments designed to detect living organism proved negative, but the apparently oxidizing characteristic of Martian soil has introduced new puzzles.

TheVikingmissions are discussed in detail. PostVikingmissions using radar and and enquiry into the possibility of a peopled mission are detailed.
Common Concepts in Materials Characterization
Authors: Kaufmann Elton N.
Published: October 2003

From a tutorial standpoint, one may view this article as a good preparatory entrance to subsequent articlesin this Encyclopedia. In an educational setting, the generally applicable topics of the articles in this category can play such a role, notwithstanding that they are each quite independent without having been sequenced with any pedagogical thread in mind.

In practice, it is expected that each of these article of this chapter will be separately valuable to users of the encyclopedia as they choose to refer to it for concepts underlying many of those exposed in units covering specific measurement methods.

Of course, not every topic covered by a section in this article will be relevant to
every
measurement method covered in subsequent articles in this Encyclopedia. However, the concepts in this article are sufficiently common to appear repeatedly in the pursuit of materials research.
General Vacuum Techniques
Authors: Singleton Jack H.
Published: October 2003

In this article we discuss the procedures and equipment used to maintain a vacuum system at pressures in the range from 10−3to 10−11torr are discussed. Total and partial pressure gauges used in this range are also described.

Because there is a wide variety of equipment, each of the various components is described, including details of their principles and technique of operation, as well as their recommended uses.

SI units are not used here. The American Vacuum Society attempted their introduction many years ago, but the more traditional units continue to dominate in this field in North America. Usage is consistent with that generally found in the current literature.

The most difficult step in designing and building a vacuum system is defining precisely the conditions required to fulfill the purpose at hand. Important factors to consider are included. Pumps play an important roll in a vacuum system. Details on pumps for the operation of most vacuume systems are given. Leak detection is addressed.
Mass and Density Measurements
Authors: Dollimore David , Samuels Alan C.
Published: October 2003

The precise measurement of mass is one of the more challenging measurement requirements that materials scientists must deal with. The use of electronic balances has become so widespread and routine that the accurate measurement of mass is often taken for granted. While government institutions such as the National Institutes of Standards and Technology (NIST) and state metrology offices enforce controls in the industrial and legal sectors, no such rigors generally affect the research laboratory. The process of peer review seldom makes assessments of the accuracy of an underlying measurement involved unless an egregious problem is brought to the surface by the reported results. In order to ensure reproducibility, any measurement process in a laboratory should be subjected to a rigorous and frequent calibration routine. This article will describe the options available to the investigator for establishing and executing such a routine; it will define the underlying terms, conditions, and standards, and will suggest appropriate reporting and documenting practices. The measurement of mass, which is a fundamental measurement of the amount of material present, will constitute the bulk of the discussion. However, the measurement of derived properties, particularly density, will also be discussed, as well as some indirect techniques used particularly by materials scientists in the determination of mass and density, such as the quartz crystal microbalance for mass measurement and the analysis of diffraction data for density determination.
Thermometry
Authors: Dollimore David , Samuels Alan C.
Published: October 2003

Thermometry is the science of measuring temperature, and thermometers are the instruments used to measure temperature. Temperature must be regarded as the scientific measure of “hotness” or “coldness.” This article is concerned with the measurement of temperatures in materials of interest to materials science, and the notion of temperature is thus limited in this discussion to that which applies to materials in the solid, liquid, or gas state (as opposed to the so‐called temperature associated with ion gases and plasmas, which is no longer limited to a measure of the internal kinetic energy of the constituent atoms).

A brief excursion into the history of temperature measurement will reveal that measurement of temperature actually preceded the modern definition of temperature and a temperature scale.

The simple expedient of sealing the instrument so that the liquid and gas were contained in the tube really marks the invention of a glass thermometer. By making the diameter of the tube small, so that the volume of the gas was considerably reduced, the liquid dilation in these sealed instruments could be used to indicate the temperature. Fahrenheit eventually substituted mercury for the “spirits of wine” earlier used as the working liquid fluid, because mercury's thermal expansion with temperature is more nearly linear. Temperature scales were then invented using two selected fixed points—usually the ice point and the blood point or the ice point and the boiling point.

The starting point for the thermodynamic treatment of temperature is to state that it is a property that determines in which direction energy will flow when it is in contact with another object. Heat flows from a higher‐temperature object to a lower‐temperature object. When two objects have the same temperature, there is no flow of heat between them and the objects are said to be in thermal equilibrium. Development of the International Temperature Scale of 1990 is detailed. Various types of thermometer are discussed as well as the need, sometimes, to control the temperature.
Symmetry in Crystallography
Authors: Steinfink Hugo
Published: October 2003

The study of crystals has fascinated humanity for centuries, with motivations ranging from scientific curiosity to the belief that they had magical powers. Early crystal science was devoted to descriptive efforts, limited to measuring interfacial angles and determining optical properties. Some investigators, such as Haüy, attempted to deduce the underlying atomic structure from the external morphology. These efforts were successful in determining the symmetry operations relating crystal faces and led to the theory of point groups, the assignment of all known crystals to only seven crystal systems, and extensive compilations of axial ratios and optical indices. Roentgen's discovery of x rays and Laue's subsequent discovery of the scattering of x rays by crystals revolutionized the study of crystallography: crystal structures—i.e., the relative location of atoms in space—could now be determined unequivocally. The benefits derived from this knowledge have enhanced fundamental science, technology, and medicine ever since and have directly contributed to the welfare of human society.

This article is designed to introduce those with limited knowledge of space groups to a topic that many find difficult.
Particle Scattering
Authors: Bastasz Robert , Eckstein Wolfgang
Published: October 2003

Atomic scattering lies at the heart of numerous materials‐analysis techniques, especially those that employ ion beams as probes. The concepts of particle scattering apply quite generally to objects ranging in size from nucleons to billiard balls, at classical as well as relativistic energies, and for both elastic and inelastic events. This article summarizes two fundamental topics in collision theory: kinematics, which governs energy and momentum transfer, and central‐field theory, which accounts for the strength of particle interactions.

Definitions of symbols used throughout this article are given in an appendix.
Sample Preparation for Metallography
Authors: Gokhale Atul B.
Published: October 2003

Metallography, the study of metal and metallic alloy structure, began at least 150 years ago with early investigations of the science behind metalworking.

Metallographic sample preparation has evolved from a black art to the highly precise scientific technique it is today. Its principal objective is the preparation of artifact‐free representative samples suitable for microstructural examination. The particular choice of a sample preparation procedure depends on the alloy system and also on the focus of the examination, which could include process optimization, quality assurance, alloy design, deformation studies, failure analysis, and reverse engineering. The details of how to make the most appropriate choice and perform the sample preparation are the subject of this unit.

Metallographic sample preparation is divided broadly into two stages. The aim of the first stage is to obtain a planar, specularly reflective surface, where the scale of the artifacts (e.g., scratches, smears, and surface deformation) is smaller than that of the microstructure. This stage commonly comprises three or four steps: sectioning, mounting (optional), mechanical abrasion, and polishing. The aim of the second stage is to make the microstructure more visible by enhancing the difference between various phases and microstructural features. This is generally accomplished by selective chemical dissolution or film formation—etching. The procedures discussed in this article are also suitable (with slight modifications) for the preparation of metal and intermetallic matrix composites as well as for semiconductors. The modifications are primarily dictated by the specific applications, e.g., the use of coupled chemical‐mechanical polishing for semiconductor junctions.

The basic steps in metallographic sample preparation are straightforward, although for each step there may be several options in terms of the techniques and materials used. Also, depending on the application, one or more of the steps may be elaborated or eliminated. This article provides guidance on choosing a suitable path for sample preparation, including advice on recognizing and correcting an unsuitable choice.

This discussion assumes access to a laboratory equipped with the requisite equipment for metallographic sample preparation. Listings of typical equipment and supplies and World Wide Web addresses for major commercial suppliers are provided for readers wishing to start or upgrade a metallography laboratory.
Computation and Theoretical Methods
Authors: Sanchez Juan M.
Published: October 2003

The articles in this category of have been selected to provide the reader with a suite of theoretical and computational tools, albeit at an introductory level, that begins with the microscopic description of electrons in solids and progresses towards the prediction of structural stability, phase equilibrium, and the simulation of microstructural evolution in real materials. This section also includes articles devoted to the theoretical principles of well established characterization techniques that are best suited to provide exacting tests to the predictions emerging from computation and simulation. It is envisioned that the topics selected will accurately reflect significant and fundamental developments in the field of computational materials science. Due to the nature of the discipline, these articles are likely to evolve as new algorithms and computational methods are developed, providing not only an up‐to‐date overview of the field, but also an important record of its evolution.
Introduction to Computation
Authors: Ceder Gerbrand
Published: October 2003

Although the basic laws that govern the atomic interactions and dynamics in materials are conceptually simple and well understood, the remarkable complexity and variety of properties that materials display at the macroscopic level seem unpredictable and are poorly understood. Such a situation of basic well‐known governing principles but complex outcomes is highly suited for a computational approach. This ultimate ambition of materials science—to predict macroscopic behavior from microscopic information (e.g., atomic composition)—has driven the impressive development of computational materials science. This article is a brief introduction to the set of articles in this category. The ultimate advantage of computing methods, both in basic materials research and in applied materials design, is the level of control one has over the system under study. The parts of this category deal with a large variety of physical phenomena.
Prediction of Phase Diagrams
Authors: Didier de Fontaine
Published: October 2003

A phase diagram is a graphical object, usually determined experimentally, indicating phase relationships in thermodynamic space. Usually, one coordinate axis represents temperature; the others may represent pressure, volume, concentrations of various components, and so on. This unit is concerned only with temperature‐concentration diagrams, limited to binary (two‐component) and ternary (three‐component) systems. Since more than one component is considered, the relevant thermodynamic systems are alloys, by definition, of metallic, ceramic, or semiconductor materials. The emphasis here is placed primarily on metallic alloys.

Phase diagrams can be classified broadly into two main categories: experimentally and theoretically determined. The object of the present unit is the theoretical determination—i.e., the calculation of phase diagrams, meaning ultimately their prediction. But calculation of phase diagrams can mean different things: there are prototype, fitted, and first‐principles approaches. Prototype diagrams are calculated under the assumption that energy parameters are knowna priorior given arbitrarily. Fitted diagrams are those whose energy parameters are fitted to known, experimentally determined diagrams or to empirical thermodynamic data. First‐principles diagrams are calculated on the basis of energy parameters calculated from essentially only the knowledge of the atomic numbers of the constituents, hence by actually solving the relevant Schrödinger equation.

Theory also enters in the experimental determination of phase diagrams, as these diagrams not only indicate the location in thermodynamic space of existing phases but also must conform to rigorous rules of thermodynamic equilibrium (stable or metastable). The fundamental rule of equality of chemical potentials imposes severe constraints on the graphical representation of phase diagrams, while also permitting an extraordinary variety of forms and shapes of phase diagrams to exist, even for binary systems.

That is one of the attractions of the study of phase diagrams, experimental or theoretical: their great topological diversity subject to strict thermodynamic constraints. In addition, phase diagrams provide essential information for the understanding and designing of materials, and so are of vital importance to materials scientists. For theoreticians, first‐principles (orab initio) calculations of phase diagrams provide enormous challenges, requiring the use of advanced techniques of quantum and statistical mechanics.
Simulation of Microstructural Evolution Using the Field Method
Authors: Wang Y. , Chen L.‐Q.
Published: October 2003

Morphological pattern formation and its spatio‐temporal evolution are among the most intriguing natural phenomena governed by nonlinear complex dynamics. These phenomena form the major study subjects of many fields including biology, hydrodynamics, chemistry, optics, materials science, ecology, geology, geomorphology, and cosmology, to name a few. In materials science, the morphological pattern is referred to as microstructure, which is characterized by the size, shape, and spatial arrangement of phases, grains, orientation variants, ferroelastic/ferroelectric/ferromagnetic domains, and/or other structural defects. These structural features usually have an intermediatemesoscopiclength scale in the range of nanometers to microns.

Microstructure plays a critical role in determining the physical properties and mechanical behavior of materials. Today the primary task of material design and manufacture is to optimize microstructures— by adjusting alloy composition and varying processing sequences—to obtain the desired properties.

Microstructural evolution is a kinetic process that involves the appearance and disappearance of various transient and metastable phases and morphologies. The optimal properties of materials are almost always associated with one of these nonequilibrium states, which is “frozen” at the application temperatures. Theoretical characterization of the transient and metastable states represents a typical nonequilibrium nonlinear and nonlocal multiparticle problem. This problem generally resists any analytical solution except in a few extremely simple cases.

With the advent of and easy access to high‐speed digital computers, computer modeling is playing an increasingly important role in the fundamental understanding of the mechanisms underlying microstructural evolution. In this article, methods recently developed for simulating the formation and dynamic evolution of complex microstructural patterns are reviewed. First, a brief account of the basic features of each method, including the conventional front‐tracking method (also referred to as the sharp‐interface method) and the new techniques without front‐tracking are given. Detailed description of the simulation technique and its practical application focuses on the field method since it is the most familiar and it is a more flexible method with broader applications. The need to link the mesoscopic microstructural simulation with atomistic calculation as well as with macroscopic process modeling and property calculation is also briefly discussed.
Molecular‐Dynamics Simulation of Surface Phenomena
Authors: Rahman Talat S.
Published: October 2003

Molecular‐dynamics (MD) simulation is a well‐developed numerical technique that involves the use of a suitable algorithm to solve the classical equations of motion for atoms interacting with a known interatomic potential. This method has been used for several decades now to illustrate and understand the temperature and pressure dependencies of dynamical phenomena in liquids, solids, and liquid‐solid interfaces.

MD simulation techniques are also well suited for studying surface phenomena, as they provide a qualitative understanding of surface structure and dynamics. This article considers the use of MD techniques to better understand surface disorder and premelting. Specifically, it examines the temperature dependence of structure and vibrational dynamics at surfaces of face‐centered cubic (fcc) metals—mainly Ag, Cu, and Ni. It also makes contact with results from other theoretical and experimental methods.

While the emphasis in this article is on metal surfaces, the MD technique has been applied over the years to a wide variety of surfaces including those of semiconductors, insulators, alloys, glasses, and simple or binary liquids. A full review of the pros and cons of the method as applied to these very interesting systems is beyond the scope of this article. However, it is worth pointing out that the success of the classical MD simulation depends to a large extent on the exactness with which the forces acting on the ion cores can be determined. On semiconductor and insulator surfaces, the success ofab initiomolecular dynamics simulations has made them more suitable for such calulations, rather than classical MD simulations.