bluuebunny/crossref_metadata_2025 huggingface dataset:
Micro Air Vehicle‐Motivated Aerodynamics
Authors: Liu Hao , Shyy Wei
Published: December 2010

MAVs (micro air vehicles) with a maximal dimension of 15 cm and nominal flight speeds around 10 m/s, operate in a Reynolds number regime of 105or lower, in which most natural flyers including insects, bats, and birds fly. Furthermore, due to their light weight and low flight speed, the MAVs' flight characteristics are substantially affected by environmental factors such as wind gust. In this chapter, we highlight the aerodynamics associated with biological flyers and MAVs, including fixed, rotary, and flapping wings. Topics covered include scaling‐law‐based analyses of flight characteristics, flapping kinematics, and power requirements, aerodynamic modeling of biological flight, Reynolds number effects, unsteady flapping‐wing aerodynamics, and implications on MAV design.
Biomimetic Optic Flow Sensors and Autopilots forMAVGuidance
Authors: Franceschini Nicolas , Ruffier Franck , Serres Julien
Published: December 2010

Here we presentexplicit control schemesthat explain how insects may navigate on the sole basis of optic flow (OF) cues,without requiring any distance or speed measurements:how they take off and land, follow the terrain, respond suitably to headwind, avoid lateral obstacles, and control their forward speed automatically. The concept of theoptic flow regulator, a feedback control system based on OF sensors, is presented. A fewOF regulatorssuffice to account for the various insect flight patterns observed. These control schemes were tested in simulation and implemented onboard two types of robots, a micro‐helicopter and a hovercraft, the behavior of which was compared with that of insects placed in similar environments. These robots were equipped with electro‐optic OF sensors inspired by the results of our microelectrode studies on motion sensitive neurons in the houseflies' eyes. The simple control schemes described here do without any conventional avionic devices such as radio‐ or laser‐altimeters, variometers, radars, sonars, GPS, and so on. They show great potential for simplifying the design of air and space vehicles, particularly for confering some autonomy upon Micro Aerial Vehicles and Micro Space Vehicles, with interesting prospects in weight reduction and low consumption.
Spacecraft Technologies and Environments: An Introduction
Authors: Zurbuchen Thomas
Published: December 2010

Space systems are affecting our lives profoundly and in a variety of ways. In approximately 50 years, space technology has evolved from its pioneering and initial demonstration period, toward a set of tools and a presence in most of our lives. This chapter provides a brief outline of the evolutionary path of space technology, its drivers and challenges, its current status, and also modern applications currently on the horizon. This chapter argues that the evolutionary trajectory of space systems is at an historic inflection point moving toward new paradigms of space exploration and entrepreneurship that can be game‐changing for the industry overall.
Low Cost Spacecraft
Authors: Fleeter Rick
Published: December 2010

An overview of small and simple space systems is presented. They have constituted the fastest evolving and growing segment of space activity since the late 1980s because of their much lower cost and shorter development time, compared to their conventional, large, and complex counterparts. Low‐cost spacecraft are capable of applications though more limited in traditional performance metrics, and also not possible or practical with conventional architectures. We discuss the overall motivation for the growth of low‐cost spacecraft, as well as guidelines and practices for development and use of smaller, lower cost systems. Finally, we discuss a few specific systems developed for a range of missions that exemplify these rules.
Launch Vehicle Design
Authors: French James R.
Published: December 2010

This chapter discusses launch vehicles in general terms, including their general characteristics. Equations are presented which are helpful in estimating theoretical performance requirements along with losses and other factors used to derive preliminary performance requirements of the vehicle itself. Major subsystems required in a launch vehicle are discussed, as are configuration issues. Performance and other characteristics of various propellant combinations are presented as an aid to the selection process.
Physiology of the Flight Environment
Authors: Gradwell David P.
Published: December 2010

Engineering developments allow mankind to explore the flight environment. However, the physical nature of the atmosphere and the mode of operation of aircraft can impose significant challenges to human physiology.

On ascent the increasingly rarefied atmosphere can deprive the aviator of an adequate supply of oxygen. They therefore can develop hypoxia, which is both insidious and hazardous, with a significant risk of death. The time required to cause injury or worse varies from many minutes to a few seconds, depending on the altitude concerned. Airborne life‐support systems must provide adequate protection to all on board an aircraft, for routine and emergency purposes. The systems themselves must be compatible with human physiological requirements and safe to operate.

In addition to the drop in atmospheric pressure on ascent the ambient temperature can fall to damaging levels and therefore cabin conditioning systems must ensure that the internal thermal environment and the cabin pressure are appropriate.

Aircrew flying high‐performance aircraft may be exposed to increased levels of acceleration, especially radial acceleration and high
G
imposes physiological challenges for which a range of counter‐measures including anti‐
G
trousers and now positive pressure breathing for
G
have been developed.
G
‐induced loss of consciousness (
G
‐loc) remains a hazard of high‐performance flight.

Vision, hearing, and balance are special senses that may be affected by flight and measures to support these and address some of the issues noted above may require engineering solutions. Aircraft designers need to be aware of the physiological aspects of flight and consider their particular requirements throughout the design of an aircraft.
Electrical Power Generation & Distribution
Authors: Moir Ian
Published: December 2010

The systems of an aircraft contain many items of equipment that need electrical power in some form. This chapter describes the way in which electrical power generation and distribution systems are designed for various types of aircraft to suit differing power demands. A description is given of typical electrical circuits and components and the way in which circuits are separated to preserve the integrity of systems using the power. Modern methods of generating AC and DC supply at varying voltages are described, as well as mechanisms for sensing overload and providing circuit protection. This chapter is an abbreviated version of Potential Flows of Moir and Seabridge, which contains considerably more detail.
Aircraft Emergency Systems
Authors: Giguère D'Arcy
Published: December 2010

Aircraft emergencies need to be handled in a very specific and very rapid manner. The main principle of an emergency system involves two stages: informing the operator and performing a mitigating action. First of all for these stages, various types of warning systems have been designed to facilitate immediate notification of the emergency, including location and severity. In some cases, the mitigating actions are carried out automatically by built‐in subsystems. In others, pilots must perform actions based on a checklist or previous training routines.

One of the most severe types of emergencies is fire. Several types of systems are generally integrated in a single aircraft, to enable the most efficient detection and control possible. Emergency oxygen must be considered for aircraft operating in certain conditions, and the various forms of storing and delivering oxygen are described in this chapter. Following a short discussion on military emergency power, a section on passenger and crew evacuation details the methods and procedures followed in various types of aircraft to ensure that humans can exit a troubled aircraft as safely as possible.
Ice Detection and Protection
Authors: Gent Roger W.
Published: December 2010

This chapter describes the phenomenon of in‐flight icing which is a potential hazard to all types of aircraft. The conditions under which icing may be encountered are described along with the most popular means of detecting their presence. Similarly, the types of ice protection systems used on aircraft are described for a range of aircraft types.
Safety and Integrity in Vehicle Systems
Authors: Drysdale Alexander T.
Published: December 2010

Safety is one of many attributes that has to be designed into a new air vehicle. This chapter describes how, by identifying system failure conditions and their various technical and non‐technical causes, the required levels of safety can be produced by design. The activities carried out, as the product is developed, will identify, analyse and control the risk of hazards. The controls identified during this process produce derived system requirements to keep the hazard risks within acceptable levels. A system safety program plan is produced and integrated with other system development activities to ensure the required safety tasks are visible to all and are properly managed and resourced. The program puts in place the organization that enables decisions to be made about the acceptability of risks identified. It identifies the hazard risk acceptance criteria to be applied and the analysis techniques to be used. A system safety assessment is provided at the completion of the development activities and is used to summarize the program work and show how well the safety requirements have been achieved. This assessment, along with other verification test evidence, and so on, is used to support the certification of the aircraft prior to its entry into service.
Electromagnetic Integration of Aircraft Systems
Authors: MacDiarmid Ian
Published: December 2010

The electromagnetic integration of complete aircraft is a multidisciplinary activity, involving aerodynamic constraints, structural design constraints, electrical installation, systems architecture, high‐frequency electrical engineering, and equipment design. It is not the intention of this chapter to replicate the many excellent textbooks on electromagnetics and electromagnetic compatibility (EMC), rather to create a way of thinking about the problem and challenges. Thus ensuring that via good engineering management processes, and a wide variety of technical solutions, (many of which are published in the literature, although a small number remain proprietary) the problem is treated appropriately. Often this has to occur in large complex organizations with diverse cultures sometimes dominated by the clearly, very important, original aircraft concerns of aerodynamics and structures.
Formulating Design Problems as Optimization Problems
Authors: Arora Jasbir S.
Published: December 2010

Proper formulation of a design problem as an optimization problem is an important step in the solution process. A procedure used to formulate optimization problems is described, discussed, and illustrated. The mathematical definition of an optimization problem has three basic elements: design variables, an objective function, and constraints. These terms have been defined and discussed in this chapter. Examples are used to illustrate the process of transcribing a design problem into an optimization problem. Then a general model that can represent many different types of design optimization problems is defined and discussed. Various concepts and terms associated with the solution of an optimization problem are explained. Many engineering design problems require numerical methods to simulate their response to the inputs. Formulation of such optimization problems involves implicit functions of the design variables. Such formulations are also presented and discussed. In addition, there are formulations that use the design variables, the analysis variables, and other intermediate variables simultaneously as unknowns of the optimization problem. These are known as alternative formulations and are also described. Practical optimization problems require numerical methods to solve them. Many good programs are available that incorporate modern computational algorithms to solve these problems once they have been formulated properly. Excel is one such program that is widely available. Its use is demonstrated by solving some of the example problems.
Review of Optimization Techniques
Authors: Venter Gerhard
Published: December 2010

A basic overview of optimization techniques is provided. The standard form of the general nonlinear, constrained optimization problem is presented, and various techniques for solving the resulting optimization problem are discussed. The techniques are classified as either local (typically gradient‐based) or global (typically non‐gradient based or evolutionary) algorithms. A great many optimization techniques exist and it is not possible to provide a complete review in the limited space available here. Instead, an effort is made to concentrate on techniques that are commonly used in engineering optimization applications. The review is kept general in nature, without considering special cases like linear programming, convex problems, multi‐objective optimization, multi‐disciplinary optimization, etc. The advantages and disadvantages of the different techniques are highlighted, and suggestions are made to aid the designer in selecting an appropriate technique for a specific problem at hand. Where possible, a short overview of a representative method is presented to aid the discussion of that particular class of algorithms.
Continuous Optimization in Aerospace Structures
Authors: Sienz Johann , Luege Mariela , Fuerle Fabian
Published: December 2010

In structural design optimization, engineers and designers aim to obtain more efficient designs with regards to measures such as weight, stiffness or frequency, for a given set of design variables. These design variables can be of different type such as material properties or geometric variables. Hence, depending on the design variables that are chosen, different techniques such as topology, shape, and size optimization have been introduced. This section presents a brief introduction to the topic in their continuous and corresponding discrete formulation based on the finite element method (FEM). Basic concepts of the advanced technologies that are involved in a typical structural design progress are also briefly included, such as: modelling analysis using the FEM, mesh generation/adaptivity, and error estimation. Illustrative examples of numerical instabilities in the FE solution, of shape and topology optimization, and of fully integrated engineering design optimization processes are also presented.
Fundamentals of Wind‐Tunnel Design
Authors: Cattafesta Louis , Bahr Chris , Mathew Jose
Published: December 2010

Wind tunnels offer an effective tool to rapidly obtain data associated with flow over scaled or full‐scale models. Given their ubiquitous nature and utility, a wind‐tunnel design project is a fairly common yet complex exercise. We therefore review in this article the fundamentals of low‐speed wind‐tunnel design. The research goals and the specific measurement requirements are discussed, as well as the various space, budget, and power constraints that guide the tunnel design. Design guidelines are provided for the most common wind‐tunnel components, including flow conditioners, contraction, test section, diffuser, drive, and other optional components. Finally, facility characterization procedures are briefly summarized, including flow uniformity, turbulence intensity, and background noise and vibration levels.
Fundamentals of Control Engineering
Authors: Atherton Derek P.
Published: December 2010

This chapter provides an introduction to the basic principles of classical feedback control. A short introduction covers the basic philosophy of feedback control and is followed by a consideration of differential equation, transfer function, and state space mathematical models for a component and how they can be entered in their different forms as an objectGin Matlab. Various basic aspects of transfer function models are then covered including, poles and zeros, relative degree and minimum phase, which is followed by some coverage of their step and frequency responses. The plotting of frequency responses using, Bode, Nyquist, and Nichols diagrams is explained together with the relevant instructions for obtaining the plots using Matlab. The basic feedback control loop is introduced and methods for evaluating its stability and relative stability discussed. Pole placement and the use of frequency domain techniques in controller design are briefly mentioned before examples of frequency domain design for a lead and a lag controller are given. The PID controller is then discussed including some comments on the early work of Ziegler and Nichols before the more modern approach of relay autotuning is briefly covered. Finally, a few comments are given on state feedback design.
Systems Engineering: Using Systems Thinking to Design Better Aerospace Systems
Authors: Burge Stuart E.
Published: December 2010

As aerospace systems have become more complex, the ability of the aerospace community to deliver a working system on‐time and on‐cost has diminished. Indeed, a review of major aerospace programs at the start of the twenty‐first century shows most to be late and over budget. There are many reasons why these programs have faltered yet there is a unifying thread that provides a rational basis for understanding the issues. That thread can be exposed by adopting a systems approach, moreover, it leads to a solution and this introductory chapter argues the case for a systems approach to the design of aerospace systems as the only realistic option to address the increasingly poor program performance. A lack of understanding of systems, Systems Thinking, Systems Approaches and Systems Engineering is cited as one of the major factors contributing to program performance. Accordingly this introductory chapter aims to:

introduce the concepts and benefits of Systems Thinking and of a Systems Engineering approach to the development of complex aerospace systems

show how Systems Engineering is the systematic application of Systems Thinking to the creation of a system

show that Systems Engineering demands the integration of people, processes and tools.
Supersonic Mixing and Combustion
Authors: Segal Corin
Published: December 2010

With the broad range of flying conditions in the hypersonic regime, the processes in the supersonic combustion chamber are subject to large thermodynamic condition variations. At the low range of the hypersonic flight regime, the heat deposition in the combustion chamber is relatively large compared with the incoming flow energy; hence, the heat deposition reduces substantially the air speed and a large pressure rise is experienced with possible flow separations. At the higher range of the hypersonic regime, close to Mach 25, which is considered the upper envelope of airbreathing propulsion, the heat addition may amount to only 10 % of the incoming airflow enthalpy. The heat release effects are less pronounced. The airspeed in the combustion chamber itself may be hypersonic and the heat deposition is distributed over a longer distance following mixing and chemical reactions. The pressure rise associated with combustion is less pronounced and is mostly due to the internal geometry of the combustion chamber. Throughout the flight domain there is a closed coupled interaction between fuel‐air mixing and heat release. In the following chapter, with the recognition that the two elements cannot realistically be uncoupled, a description of the salient features of mixing and combustion is presented.
Air Transportation and Operations
Authors: Curran Ricky , van der Zwan Frank
Published: December 2010

The chapter considers the air transportation system in terms of its current structure, key components, and future challenges. Consequently, the current context of sustained growth is considered along with the impact, stakeholders, and evolving legal agreements. Future evolution of the system is then considered relative such initiatives such as SESAR and the emission trading scheme before going on to consider the key system components. Consequently, airlines, airports and Air Traffic Management are considered in terms of structure and organization, and operations and performance.
Obstacle Avoidance: Static Obstacles
Authors: Shanmugavel Madhavan , Tsourdos Antonios , White Brian
Published: December 2010

This article presents an overview of obstacle avoidance of static obstacles of autonomous vehicles. Two methods are discussed to handle the known and unknown obstacles. A brief introduction of road map methods are discussed which are used to avoid static obstacles which are known a priori. The pop‐up or unknown obstacles are handled by reactive method such as potential field and by replanning the paths. These methods avoid the obstacles by changing the original path produced by path planning. Relevant research on the obstacle avoidance is presented where optimization and other approaches are discussed.
Basic Principles – Gas Turbine Compatibility – Gas Turbine Aspects
Authors: Breuer Thomas , Bissinger Norbert C.
Published: December 2010

Engine/intake compatibility covers the mutual dependencies between the aircraft intake and the gas turbine. Flow physical effects in both the intake and/or the gas turbine can reduce stability margins of the propulsion system dramatically, possibly resulting in unstable performance or engine flameout. Besides exhibiting optimal performance it is of utmost importance that stable propulsion operation in the whole flight envelope of a jet aircraft is ensured. In this chapter, the effects of intake flow distortions on the operation conditions of engine components and the whole gas turbine will be described. Methods for demonstration of engine distortion tolerance and carefree handling are presented. Mechanical loads due to compatibility effects and their influence on engine life are highlighted.

Note: Intake aerodynamics aspects of distortion are dealt with in the companion Basic Principles: Gas Turbine Compatibility – Intake Aerodynamic Aspects.
Heat Pipes and Thermosyphons
Authors: Chen Tailian , Kim Jungho
Published: December 2010

There are numerous applications of heat pipes and thermosyphons. Heat pipes have been extensively used for thermal management of aerospace electronic devices. Readers can refer to the subject of heat pipe applications in aerospace and aircraft in this encyclopedia. This chapter provides an overview of fundamental concepts of heat pipes and thermosyphons, and some important applications of the two technologies.
Probe and Drogue Aerial Refueling Systems
Authors: Purdy Stephen I.
Published: December 2010

Probe
and
drogue
refuelling was invented by Sir Alan Cobham in 1950 and has undergone and continues to undergo development since that date. This chapter describes modern state of the art and provides references for those interested in the history of the subject. The various types of
tanker
are described and reference is made to the overall configuration of their refuelling systems. The installation of pod and
fuselage refuelling systems
is discussed and the operation of modern systems and their sub‐systems is discussed in some detail. The key aspects of any system are the
hose drum drive
control and
fuel systems
, performance requirements and salient operational and safety issues are discussed. References are provided to the most important aircraft and equipment specifications and operational procedures. Tanker operational envelopes and refuelling speeds are dictated by
receiver
requirements and the tanker configurations for helicopter, tilt rotor and fast jet refuelling are all described along with the structural adaptations and drogue configurations relevant to each. The chapter concludes with a brief look at future technologies and the long‐term outlook for the aerial refuelling tanker.
Space Tourism
Authors: Livingston David M.
Published: December 2010

Space tourism is an exciting, developing, and economically promising new industry. It is also an industry replete with both traditional and highly unusual risk factors, which depending on how a particular space tourism flight or even the industry develops, can be extremely profitable or highly damaging. This chapter examines the space tourism industry from a marketing and company perspective. The benefits to the tourists and the business as well as personal risk factors are examined. Since state and federal government regulations play an important role in shaping the space tourism industry, this chapter addresses the most important part of the primary laws and regulations in place now to regulate and control the industry. Finally, we look at the suborbital and orbital space tourism companies to see what they say about their space plane development, flight profiles, tourist adventure, and space tourism business plans.
Basics ofMAVFlight Control
Authors: Żbikowski Rafał
Published: December 2010

This chapter summarizes the basics of flight control practiced in large‐scale aviation, focusing on the aspects which are relevant to professional design of MAV flight control. Noting that the flight dynamics knowledge is the cornerstone of flight control design, the relation of control design to mission planning, navigation, and guidance is first described. The key notion of feedback is then explained together with the dependence of its implementation on sensing, actuating, and computing technology. This is followed by description of the fundamental importance of linear approach to feedback control design. Finally, two non‐linear flight control design methods are presented: gain scheduling and bifurcation control. The chapter concludes with recommendation to apply the relevant existing flight dynamics and control knowledge to MAV flight control design.
Ram Accelerator
Authors: Bruckner Adam P. , Knowlen Carl
Published: December 2010

The ram accelerator is a scalable hypervelocity launcher capable, in principle, of accelerating projectiles to velocities greater than 8 km s−11. The device operates as an in‐bore ramjet in which a subcaliber projectile, shaped like the centerbody of a cylindrical supersonic ramjet, is propelled through a stationary tube filled with a pressurized gaseous propellant mixture of fuel, oxidizer, and diluent. This propellant burns near the base of the moving projectile, generating thrust. The chemical energy density and speed of sound of the propellant can be adjusted, via gas pressure and composition, to control the in‐tube Mach number and acceleration history. Successful ram accelerator operation has been obtained at gas fill pressures up to 200 bar and projectile velocities up to 2.7 km s−1. Scaling has been demonstrated in bore sizes ranging from 25 to 120 mm in research facilities around the world. Potential applications of the ram accelerator include hypervelocity impact studies, hypersonic propulsion research, and direct launch of acceleration‐insensitive payloads to low Earth orbit. An overview of ram accelerator technology and representative experimental results from a 38 mm‐bore ram accelerator facility are presented.
Self‐Sharpening Mechanism of the Sea Urchin Tooth
Authors: Killian Christopher E. , Metzler Rebecca A. , Gong Yutao , Churchill Tyler H. , Olson Ian C. , Trubetskoy Vasily , Christensen Matthew B. , Fournelle John H. , De Carlo Francesco , Cohen Sidney , Mahamid Julia , Scholl Andreas , Young Anthony , Doran Andrew , Wilt Fred H. , Coppersmith Susan N. , Gilbert Pupa U. P. A.
Published: December 2010

The sea urchin tooth is a mosaic of calcite crystals shaped precisely into plates and fibers, cemented together by a robust calcitic polycrystalline matrix. The tooth is formed continuously at one end, while it grinds and wears at the opposite end, the sharp tip. Remarkably, these teeth enable the sea urchin to scrape and bore holes into rock, yet the teeth remain sharp rather than dull with use. Here we describe the detailed structure of the tooth of the California purple sea urchin Strongylocentrotus purpuratus, and focus on the self‐sharpening mechanism. Using high‐resolution X‐ray photoelectron emission spectromicroscopy (X‐PEEM), scanning electron microscopy (SEM), EDX analysis, nanoindentation, and X‐ray micro‐tomography, we deduce that the sea urchin tooth self‐sharpens by fracturing at discontinuities in the material. These are organic layers surrounding plates and fibers that behave as the “fault lines” in the tooth structure, as shown by nanoindentation. Shedding of tooth components at these discontinuities exposes the robust central part of the tooth, aptly termed “the stone”, which becomes the grinding tip. The precise design and position of the plates and fibers determines the profile of the tooth tip, so as the tooth wears it maintains a tip that is continually renewed and remains sharp. This strategy may be used for the top‐down or bottom‐up fabrication of lamellar materials, to be used for mechanical functions at the nano‐ and micrometer scale.
Strategies for Post‐Synthesis Alignment and Immobilization of Carbon Nanotubes
Authors: Druzhinina Tamara , Hoeppener Stephanie , Schubert Ulrich S.
Published: December 2010

Carbon nanotubes (CNTs) have developed into a standard material used as a building block for nanotechnological developments. Based on the unique properties that make CNTs useful for many different applications in nanotechnology, optics, electronics, and material science, there has been a rapid development of this research area and many different applications have emerged in the past few years. Frequently, the alignment and immobilization of CNTs play an important role for many applications and different strategies, in particular post‐synthesis approaches, can be applied. Recent developments of different techniques to immobilize and align carbon nanotubes are discussed and classified into three main categories: chemical immobilization and alignment, physical immobilization and alignment, and the use of external fields for these purposes. Many of the techniques involve multiple steps and may also cross these rather crudely defined boundaries. As such, the techniques are classified according to their most important or unique step.
Bionanoelectronics
Authors: Noy Aleksandr
Published: December 2010

Every cell in a living organisms performs a complex array of functions using a vast arsenal of proteins, ion channels, pumps, motors, signaling molecules, and cargo carriers. With all the progress that humankind has made to date in the development of sophisticated machinery and computing capabilities, understanding and communicating with living systems on that level of complexity lags behind. A breakthrough in these capabilities could only come if a way is found to integrate biological components into artificial devices. The central obstacle for this vision of bionanoelectronics is the absence of a versatile interface that facilitates two‐way communication between biological and electronic structures. 1D nanomaterials, such as nanotubes and nanowires, open up the possibility of constructing tight interfaces that could enable such bidirectional flow of information. This report discusses the overall progress in building such interfaces on the level of individual proteins and whole cells and focuses on the latest efforts to create device platforms that integrate membrane proteins, channels, and pumps with nanowire bioelectronics.
Trapping the Oxyallyl Cation Intermediate Derived from the Nazarov Cyclization of Allenyl Vinyl Ketones with Nitrogen Heterocycles
Authors: Marx Vanessa M. , LeFort François M. , Burnell D. Jean
Published: December 2010

The cationic intermediate of the Lewis acid‐initiated Nazarov cyclization of an allenyl vinyl ketone (AVK) was trapped by pyrroles and indoles. The yields ranged from modest to high (up to 93%), and in both cases, only two of the three possible products were produced. Cyclopent‐2‐enones substituted at the 5‐position were predominantly produced, however with increasing alkyl substitution or placement of an electron‐withdrawing group on the nitrogen, an alternative regioisomer could also be formed. The results of this study suggest that a position α to the oxygen of the oxyallyl cation is the electronically preferred trapping site, whilst an exocyclic position is preferred for more sterically encumbered reacting partners.
Isolation and expression analysis of a homolog of the 14–3–3 epsilon gene in the diamondback moth, Plutella xylostella
Authors: Yoo Ji Yeon , Hwang Se Hui , Han Yeon Soo , Cho Saeyoull
Published: December 2010

A full‐length 14–3–3 gene homolog (also referred to as the Px14–3–3 epsilon “ε” or Px14–3–3ε gene) was cloned from cDNA of the diamondback moth, Plutella xylostella. The Px14–3–3 transcript is 789 nucleotides in length, and the predicted polypeptide is 263 amino acids in length, with a calculated molecular mass of 29.6 kDa. The Px14–3–3 gene contains the typical and predicted 14–3–3 domains and motifs. The amino acid sequence of the diamondback moth 14–3–3 gene is very similar to that of other insect epsilons (ε) but not to other insect zetas (ζ). In particular, the protein sequence of the Px14–3–3 gene shows high identity to the Bombyx mori epsilon (96.2%). Western blot analysis using an antibody against Px14–3–3ε verified the expression of 14–3–3ε in the larval, pupal, and adult stages. The Px14–3–3ε expression patterns in all the different tissue types were examined in the fourth instar larvae. Px14–3–3ε was detected in every tissue examined, including the body fat, hemocytes, brain, gut, and cuticle. © 2010 Wiley Periodicals, Inc.
Synthesis, Antihypertensive Activity, and 3D‐QSAR Studies of Some New p‐Hydroxybenzohydrazide Derivatives
Authors: Bhole Ritesh P. , Bhusari Kishore P.
Published: December 2010

p‐Hydroxybenzohydrazide 2 on treatment with aromatic/aliphatic aldehyde followed by cyclization with carbon disulphide afforded compounds 4a–4n. Also, compound 2 by treatment of substituted isothiocyanate followed by the treatment of chloroacetic acid yields the corresponding compounds 6a–6i. All the test compounds were assayed for antihypertensive activity by non‐invasive blood pressure measurement and invasive blood pressure measurement methods. The test compounds showed significant antihypertensive activity. The intact compounds were subjected to 3D‐QSAR studies. The 3D‐QSAR analysis was carried out by PHASE program and a statistically reliable model with good predictive power (r2 = 0.98, q2 = 0.74) was achieved. The 3D‐QSAR plots illustrated insights into the structure‐activity relationship of these compounds which may aid in the design of potent p‐hydroxybenzohydrazide derivatives as antihypertensive agents.
Synthesis and Biological Evaluation of Some Novel Fused Pyrazolopyrimidines as Potential Anticancer and Antimicrobial Agents
Authors: Abd El Razik Heba A. , Abdel Wahab Abeer E.
Published: December 2010

Synthesis and evaluation of anticancer and antimicrobial activity of some novel pyrazolopyrimidines and fused pyrazolopyrimidines are reported. Twelve analogs were selected to be evaluated for their in vitro anticancer potential against a panel of three human tumor cell lines: hepatocellular carcinoma HepG2, cervical carcinoma HelaS3 and colon carcinoma CaCo. The obtained data revealed that eight compounds namely; 6b, 6d, 7c, 8c, 10b, 12b, 13a and 13b were able to exhibit variable degrees of anticancer activities against the three used cell lines, of which compound 6d proved to be the most active. On the other hand, all the newly synthesized compounds were subjected to in vitro antibacterial and antifungal screening. Almost all the tested compounds were found to possess variable degrees of antimicrobial activities. Collectively, compounds 7c, 8c, 12b, 13a and 13b could be considered as possible agents with dual anticancer and antimicrobial activities.
Synthesis and Anticonvulsant Activity of New N‐Mannich Bases Derived from 5‐Cyclopropyl‐5‐phenyl‐hydantoins
Authors: Byrtus Hanna , Obniska Jolanta , Czopek Anna , Kamiński Krzysztof
Published: December 2010

Synthesis, physicochemical and anticonvulsant properties of new N‐Mannich bases 3–24 derived from 5‐cyclopropyl‐5‐phenyl‐ and 5‐cyclopropyl‐5‐(4‐chlorophenyl)‐hydantoins were described here. Initial anticonvulsant screening was performed using intraperitoneal (i.p.) maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) seizures tests. Selected derivatives were also screened in the 6‐Hz test. The neurotoxicity was determined applying the rotorod test. The pharmacological results revealed that the majority of compounds were effective in MES and/or scPTZ tests. The quantitative studies after oral administration into rats showed that several molecules were more potent than phenytoin and ethosuximide which were used as reference antiepileptic drugs. From the whole series the most active was 3‐[(4‐phenylpiperazin‐1‐yl)‐methyl]‐5‐cyclopropyl‐5‐phenyl‐imidazolidine‐2,4‐dione (3) with the ED50 value of 5.29 mg/kg in the MES test.
Synthesis of Some Chalcones and Pyrazolines Carrying Morpholinophenyl Moiety as Potential Anti‐Inflammatory Agents
Authors: Khalil Omneya M.
Published: December 2010

Chalcones of 2a–f and their corresponding products, pyrazolines 3a–f, were synthesized and evaluated for their anti‐inflammatory activity against carrageenan edema in albino rats at a dose of 10 mg/kg. All the compounds of this series showed promising anti‐inflammatory activity. The most active compounds of this series, 2a, 2b, and 2d, were found to be most potent. They showed higher percentage of inhibition of edema than the standard drug indomethacin.
DFT Study of Chiral‐Phosphoric‐Acid‐Catalyzed Enantioselective Friedel–Crafts Reaction of Indole with Nitroalkene: Bifunctionality and Substituent Effect of Phosphoric Acid
Authors: Hirata Takashi , Yamanaka Masahiro
Published: December 2010

The enantioselective Friedel–Crafts reaction of indoles with nitroalkenes proceeds catalytically by means of a chiral‐phosphoric‐acid catalyst to afford products with high enantioselectivities (up to 91 % ee). The use of a 3,3′‐SiPh3‐substituted (R)‐binol‐derived (binol=1,1′‐binaphthyl‐2,2′‐diol) catalyst and a free indole that bears an NH moiety is essential to achieving high enantioselectivity as well as high yield. To elucidate the reaction mechanism and the origin of the high enantioselectivity, DFT calculations were carried out. The reaction proceeded through a cyclic transition state formed by the two‐point binding of both substrates to the conjugated OPO moiety of the catalyst, in which indoles and nitroalkenes could be simultaneously activated by Brønsted acidic (proton) and basic (phosphoryl oxygen) sites, respectively. The enantioselectivity was entirely controlled by the steric effect between the 3,3′‐substituent group on the (R)‐binol‐derived phosphoric acid catalyst and the indole ring. When the sterically demanding SiPh3 group was used as the 3,3′‐substituent group, the energy difference between the most‐stable diastereomeric transition states that afforded the S and R products was increased to lead to the high enantioselectivity in agreement with the experimental results.
2D Hexagonal Tilings Based on Triangular and Hexagonal Structural Units in the Self‐Assembly of Thiacalix[4]arene Tetrasulfonate on an Au(111) Surface
Authors: Chen Ting , Yan Hui‐Juan , Zhang Xu , Wang Dong , Wan Li‐Jun
Published: December 2010

The formation of several molecular 2D tilings with long‐range periodicity, including the Kagome network, distorted Kagome network, and snub trihexagonal tiling from the adsorption and assembly of thiacalix[4]arene tetrasulfonate (TCAS) at the 0.1 M HClO4/Au(111) interface has been investigated by electrochemical scanning tunneling microscopy (STM). The internal structures of the tilings have been disclosed by high‐resolution STM images. The basic structural motifs, namely, the tiles of these tilings are similar, including triangular units and hexagonal units. Due to the different arrangement of the molecules within the triangular units, tiles with different configurations are formed, which further result in the polymorphism of the 2D tiling. This result is of significance for understanding the formation of 2D tiling as well as the design and construction of molecular self‐assembled nanostructures.
Telomere, DNA damage, and oxidative stress in stem cell aging
Authors: Zhang Junling , Ju Zhenyu
Published: December 2010

“Stem cell aging” is a novel concept that developed together with the advances of stem cell biology, especially the sophisticated prospectively isolation and characterization of multipotent somatic tissue stem cells. Although being immortal in principle, stem cells can also undergo aging processes and potentially contribute to organismal aging. The impact of an age‐dependent decline of stem cell function weighs differently in organs with high or low rates of cell turnover. Nonetheless, most of the organ systems undergo age‐dependent loss of homeostasis and functionality, and emerging evidence showed that this has to do with the aging of resident stem cells in the organ systems. The mechanisms of stem cell aging and its real contribution to human aging remain to be defined. Many antitumor mechanisms protect potential malignant transformation of stem cell by inducing apoptosis or senescence but simultaneously provoke stem cell aging. In this review, we try to discuss several concept of stem cell aging and summarize recent progression on the molecular mechanisms of stem cell aging. Birth Defects Research (Part C) 90:297–307, 2010. © 2010 Wiley‐Liss, Inc.
Noncanonical Wnt signaling in vertebrate development, stem cells, and diseases
Authors: Sugimura Ryohichi , Li Linheng
Published: December 2010

Wnt signaling regulates many aspects of vertebrate development and adult stem cells. Deregulation of Wnt signaling causes development defect and cancer. The signaling is categorized in two pathways: canonical and noncanonical. Both pathways are initiated by Wnt ligands and Frizzled receptors. Canonical pathway leads to β‐catenin:T‐cell factor/lymphoid enhancer factor‐mediated gene expression, which regulates proliferation and differentiation of cells. Noncanonical Wnt signaling is mediated by intracellular calcium ion and JNK. This signaling leads to NFAT, a key transcriptional factor regulating gene expression. In addition, β‐catenin:T‐cell factor/lymphoid enhancer factor‐mediated gene expression is downregulated by CaMKII‐TAK1‐NLK. Cellular polarity and motility are the main outcomes of the signaling. During development, noncanonical Wnt signaling is required for tissue formation. Recent studies have shown that atypical cadherin Flamingo contributes to noncanonical Wnt signaling by directing the migration of cells. Also, noncanonical Wnt signaling is required for maintenance of adult stem cells. In the field of cancer research, noncanonical Wnt signaling has been considered a tumor suppressor; however, recent evidence has shown that the signaling also enhances cancer progression in the later stages of disease. In this review, we describe and discuss components of noncanonical Wnt signaling, diseases caused by deregulation of the signaling, regulation of adult stem cells by the signaling, and implications in cancer biology. Birth Defects Research (Part C) 90:243–256, 2010. © 2010 Wiley‐Liss, Inc.
Elucidation of the Biosynthesis and Degradation of Allantofuranone by Isotopic Labelling and Fermentation of Modified Precursors
Authors: Schüffler Anja , Liermann Johannes C. , Opatz Till , Anke Timm
Published: December 2010

Feeding experiments with the ascomycete Allantophomopsis lycopodina indicated that the potent fungistatic allantofuranone is biosynthesized from phenylalanine. Further experiments with synthetic precursors gave evidence that the naturally occurring polyporic acid serves as a key intermediate in the biosynthesis. In addition to the formation of allantofuranone, its abiotic and metabolic degradation were investigated.
A comparison of charlson and elixhauser comorbidity measures to predict colorectal cancer survival using administrative health data
Authors: Lieffers Jessica R. , Baracos Vickie E. , Winget Marcy , Fassbender Konrad
Published: December 2010

BACKGROUND:

Cancer survival is related to features of the primary malignancy and concurrent presence of nonmalignant diseases (comorbidities), including weight‐related conditions (obesity, weight loss). The Charlson and Elixhauser methods are 2 well‐known methods that take comorbidities into account when explaining survival. They differ in both the number and categorization of comorbidities.

METHODS:

Cancer, comorbidity, and survival data were acquired from inpatient administrative hospital records in 574 colorectal cancer patients. Robust Poisson regression was used to analyze 2‐ and 3‐year survival according to cancer features and comorbidities classified by the Charlson and Elixhauser methods. Data for weight‐related conditions (body mass index, weight loss) and performance status were acquired upon a new patient visit to the regional cancer center. Discrimination was assessed with the concordance (c) statistic.

RESULTS:

A base model (age, sex, stage) had excellent discrimination (c‐statistic, 0.824 [2‐year survival] and 0.827 [3‐year survival]). The addition of Charlson comorbidities did not outperform the base model (c‐statistic, 0.831 [2‐year survival] and 0.833 [3‐year survival]). Elixhauser comorbidities added higher discrimination compared with the base model, both in stage and overall (c‐statistic, 0.852 [2‐year survival] and 0.854 [3‐year survival]; P < .01). The greatest increase in the c‐statistic contributed by the addition of the Elixhauser comorbidities occurred in stage II patients (increased from 0.683 to 0.838). Overall, the Elixhauser comorbidities outperformed the Charlson comorbidities (P < .05). The use of self‐reported weight and performance status data significantly increased discrimination by the Elixhauser method in 2‐year but not 3‐year survival.

CONCLUSIONS:

The Elixhauser method is a superior comorbidity risk‐adjustment model for colorectal cancer survival prediction. Cancer 2011. © 2010 American Cancer Society.
Racial differences in the presentation and outcomes of diffuse large B‐cell lymphoma in the United States
Authors: Shenoy Pareen J. , Malik Neha , Nooka Ajay , Sinha Rajni , Ward Kevin C. , Brawley Otis W. , Lipscomb Joseph , Flowers Christopher R.
Published: December 2010

BACKGROUND:

Diffuse large B‐cell lymphoma (DLBCL) is often cured with standard chemoimmunotherapy, but there is great heterogeneity in presentation and outcomes.

METHODS:

By using Surveillance, Epidemiology, and End Results (SEER) data from 13 registries across the United States, the authors examined differences in incidence and survival for DLBCL by race. International Classification of Diseases for Oncology, third edition histology codes 9678, 9679, 9680, and 9684 were used to identify cases.

RESULTS:

From 1992 to 2007, 38,522 cases of DLBCL were recorded in SEER. Sixty‐five percent of black patients compared with 37% of white patients presented at age ≤60 years, 52% of blacks compared with 44% of whites presented with stage III/IV disease, and 31% of black versus 24% of white patients presented with B symptoms (all P < .001). Although survival improved by era of diagnosis for all races (log rank P < .001), 2‐year relative survival rates were better for women than men (61% vs 58%, P < .001) and white than black patients (60% vs 50%, P < .001). Black race, male sex, age at diagnosis >60, advanced stage, and B symptoms at diagnosis were predictors of worse survival (P < .001).

CONCLUSIONS:

Black patients with DLBCL in the United States present at younger age, more advanced stage, and have inferior survival. Epidemiological studies that examine the biological variants of DLBCL in concert with race are needed to elucidate the etiology of these disparities. Cancer 2011;. © 2010 American Cancer Society.