bluuebunny/crossref_metadata_2025 huggingface dataset:
Anti‐proliferative and Pro‐apoptotic Properties of 3‐Bromoacetoxy Calcidiol in High‐risk Neuroblastoma
Authors: Lange Thilo S. , Singh Rakesh K. , Kim Kyu Kwang , Zou Yongping , Kalkunte Satyan S. , Sholler Giselle L. , Swamy Narasimha , Brard Laurent
Published: October 2007

The cytotoxic, anti‐proliferative and apoptotic effects of 3‐Bromoacetoxy Calcidiol (B3CD), a derivative of vitamin D3 precursor calcidiol, on human neuroblastoma (NB) cells were examined. NB, predominantly a tumor of early childhood, is the most common extracranial solid tumor. Despite aggressive treatments, survival for advanced stages remains low and novel treatment strategies are needed. B3CD‐induced apoptosis in various neuroblastic cells via caspases‐3 and ‐9 activation. B3CD upregulated mitochondrial pro‐apoptotic Bax and anti‐apoptotic Bcl‐2 expression, caused cytochrome c release, downregulated N‐Myc expression and activated pro‐survival marker Akt. Accordingly, B3CD treatment dose dependently reduced the viability of NB cells with IC50 values between 1 and 3 μm. The cytotoxicity of B3CD was significantly higher than for the calcemic parent‐compound vitamin D3 (IC50 between 10 and 30 μm). Further studies revealed that B3CD treatment inhibits the proliferation of NB cells at low concentrations (IC50 between 30 and 100 nm). Cell cycle analysis showed a dramatic increase in the apoptotic sub‐diploidal population along with a cell cycle block. In summary, the present study shows that B3CD is toxic to NB cells via suppression of cell proliferation and cell viability by caspase activation and regulation of survival signals. These results suggest that B3CD could be developed as a treatment for NB.
Biocompatibility of retrograde root filling materials: A review
Authors: Bodrumlu Emre
Published: October 2007

The aim of a retrograde filling material is to fill the apical canal space and to obtain a hermetic seal between the periodontium and the root canal system. Several materials have been suggested for root‐end filling including: amalgam, gutta‐percha, zinc oxide–eugenol cements, glass ionomer cement, gold foil pellets, Cavit, composite resin and mineral trioxide aggregate (MTA). Super‐ethoxy benzoic acid and MTA are the most suitable materials and provide better results in apicoectomy procedures than other filling materials. Unfortunately, the ideal material for this purpose has yet to be found. This article is a review of the biocompatibility of retrograde filling materials.
Do markets enhance convergence on international standards? The case of financial regulation
Authors: Chey Hyoung‐Kyu
Published: October 2007

Why do countries that did not participate in the establishment of international standards converge on them in the absence of external coercion? The market‐based perspective asserts that market forces enhance cross‐national convergence on international standards. This paper challenges the market‐based perspective, focusing on compliance with the 1988 Basel Capital Accord in South Korea and Taiwan. First, it argues that adoption of the Basel Capital Accord by these countries was mainly driven by their regulatory authorities’ concern about the potential risk of foreign market closure to noncompliant banks. Second, it demonstrates that enforcement by the two countries’ regulatory authorities was crucial in ensuring compliance. These findings suggest that national regulatory authorities are still key actors in voluntary convergence on international standards.
Renminbi Derivatives: Recent Development and Issues
Authors: Peng Wensheng , Shu Chang , Yip Raymond
Published: October 2007

This study reviews the developments in the onshore and offshore renminbi derivatives markets. The onshore market has seen a rapid build‐up in the market infrastructure and price discovery mechanism in the past year, with empirical evidence suggesting that its pricing is increasingly determined by financial fundamentals, such as the covered interest rate parity. However, the growth of the market has been restrained by restrictions on the participant base, limited variations in the RMB/US$ exchange rate, market participants’lack of technical capacity and experience, and inadequate supporting financial market infrastructure. The non‐deliverable forward (NDF) market, concentrated in Hong Kong and Singapore, is more developed, but has the drawback that its pricing is not tied to financial fundamentals. The comparison between onshore and offshore markets suggests that two issues are of particular importance for future derivatives market development in China: the balance between regulation and development, and the relationship between onshore and offshore markets.
A Bend in the Road: Subject Personal Pronoun Expression in Spanish after 30 Years of Sociolinguistic Research
Authors: Flores‐Ferrán Nydia
Published: October 2007

Scholars have investigated the variable use of subject personal pronouns (SPP) in oral and written discourse using a sociolinguistic framework for over three decades. The focal point of their research has been to determine the linguistic, stylistic, and social factors that influence speakers to express or not express the SPP as inYo canto(I sing), andCanto[(I) sing]. Several linguistic, stylistic, and social factors have been found to condition the use of the expressed SPP. Nonetheless, this syntactic variable remains highly debated among scholars who investigate Spanish in the US, Latin American, and Peninsular varieties. The remarks in the article are suggestive rather than probative as the discussion represents an overview. It also provides a gateway of interest regarding this feature. Given the many empirical studies that have investigated this feature, the metaphor of ‘the bend in the road’ represents a slight turn that should guide our thoughts for future research.
Hydrodynamic Cavitation to Improve Bulk Fluid to Surface Mass Transfer in a Nonimmersed Ultraviolet System for Minimal Processing of Opaque and Transparent Fluid Foods
Authors: Milly P.J. , Toledo R.T. , Chen J. , Kazem B.
Published: October 2007

ABSTRACT:  Ultraviolet (UV)‐induced chemical reactions and inactivation of microorganisms in transparent and opaque fluids are strongly dependent upon the homogenous exposure of the target species to the UV irradiation. Current UV technologies used in water disinfection and food preservation applications have limited efficacy due to suspended particles shading target species. An Ultraviolet‐Shockwave Power™ Reactor (UV‐SPR) consisting of an inner rotating rotor and a stationary quartz housing and 2 end plates was used to induce ‘controlled cavitation.’ Eight UV low‐pressure mercury lamps spaced uniformly were installed lengthwise around the quartz housing periphery. A KI to I3−chemical dosimeter for UV was used to quantify photons received by fluid in the annular space of the SPR. UV dose (J/m2) increased from 97 J/m2 at 0 rpm to over 700 J/m2 for SPR speeds above 2400 rpm. Inactivation of E. coli 25922 in apple juice and skim milk in the UV‐SPR at exit temperatures below 45 °C was greater than 4.5 and 3 logs, respectively. The UV‐SPR system proved successful in increasing the mass transfer of transparent and opaque fluid to the UV irradiated surface.
The utilization of rare blood donors
Authors: Nance S. J. ,   MS, MT (ASCP) SBB
Published: October 2007

When transfusion is needed for a patient with a rare blood type and the corresponding antibody, it can be challenging and lead to delays in transfusion. Sometimes, the blood cannot be found. Globally, the community of rare donor facilities is extremely collaborative and is quickly engaged in locating and delivering blood to the patients in need of rare blood types. Identifying the rare donor is a resource‐intensive activity in every country especially in times of shrinking human and reagent resources. This paper will discuss the process flow for obtaining blood for patient's requiring rare types and the critical steps for each facility in the supply chain. The local facility plays a vital role in the knowledge of patient need and interaction with the patient's physician. The national facility that coordinates obtaining rare blood internationally also plays a vital role. The International Blood Group Reference Laboratory in Bristol as one of its roles, maintains the International Rare Donor Panel and also plays a vital role. These three roles hold the responsibility for collaboration to identify and obtain blood for patients in need. While there are differences in each country's definition of rare blood types, all are in agreement to assist when a country needs blood products. The International Society Blood Transfusion working party for rare donors plays a critical, collaborative role in developing processes between countries to further rare blood transfers between countries and providing expertise when needed. Outcome data are difficult to obtain, therefore success and ultimate improvement is a challenge. This challenge is one that the needs to be met to improve patient outcomes in cases where rare blood is needed throughout the world.
A Framework for Explaining Aggression Involving Groups
Authors: Meier Brian P. , Hinsz Verlin B. , Heimerdinger Sarah R.
Published: October 2007

Aggression involving groups (versus individuals) can be particularly severe (e.g., hazings). Although an impressive amount of experimental research on the aggression of individuals exists, relatively less experimental research on aggression involving groups exists. We use existing theories of aggression and the available research to present a framework of aggression when groups are involved. We propose a provisional model that suggests that the extent of aggression to be committed depends on the composition of both source (i.e., perpetrators – group or individual) and target (i.e., victims – group or individual) entities. Evidence suggests that groups commit and receive more aggression than individuals. We propose that accessible hostile thoughts and the experience of negative affect contribute to the target effect (i.e., more aggression committed toward groups versus individuals), whereas disinhibition processes and arousal contribute to the source effect (i.e., more aggression committed by groups versus individuals). Our framework can guide future theory and research on aggression involving groups.
Identification of patients with chronic obstructive pulmonary disease (COPD) by measurement of plasma biomarkers
Authors: Shaker Saher B. , von Wachenfeldt Karin A. , Larsson Susanne , Mile Iréne , Persdotter Sofia , Dahlbäck Magnus , Broberg Per , Stoel Berend , Bach Karen S. , Hestad Marianne , Fehniger Thomas E. , Dirksen Asger
Published: October 2007

Introduction:  Inflammation is an important constituent of the pathology of chronic obstructive pulmonary disease (COPD), leading to alveolar destruction and airway remodelling.

Objective:  The aim of this study was to assess the difference in plasma biomarkers of inflammation between asymptomatic smokers and patients with COPD.

Methods:  We used commercially available enzyme‐linked immunosorbent assay kits to measure the plasma levels of tumour necrosis factor‐α (TNF‐α), interleukin‐8 (IL‐8), matrix metalloproteinase‐9 (MMP‐9), monocyte chemotactic protein‐1 (MCP‐1), tissue inhibitor of metalloproteinase‐1 (TIMP‐1) and tissue inhibitor of metalloproteinase‐2 (TIMP‐2) on two occasions with a 2‐week interval in patients with COPD (n = 20), asymptomatic smokers (n = 10) and healthy lifelong non‐smokers (n = 10). The participants were characterised clinically, physiologically and by quantitative computed tomography by measuring the relative area of emphysema below −910 Hounsfield units (RA‐910).

Results:  The results of the biomarker measurements on the two occasions were highly reproducible. Patients with COPD had significantly higher plasma levels of IL‐8 (P = 0.004) and significantly lower levels of TIMP‐1 (P = 0.02) than smokers and non‐smokers. There was no statistically significant difference between the three groups in the level of TNF‐α, MMP‐9, MCP‐1 and TIMP‐2. The IL‐8/TIMP‐1 ratio correlated significantly with the degree of airway obstruction measured as forced expiratory volume in 1 second (FEV1) % predicted (r = −0.47, P < 0.01); with the diffusion capacity (r = −0.41, P < 0.01); and with the grade of emphysema measured as RA‐910 (r = 0.39, P = 0.01).

Conclusion:  These findings suggest that the measurement of plasma biomarkers, such as IL‐8/TIMP‐1, may aid to discriminate patients with COPD from smokers at lower risk of developing COPD.

Please cite this paper as: Shaker SB, von Wachenfeldt KA, Larsson S, Mile I, Persdotter S, Dahlbäck M, Broberg P, Stoel B, Bach KS, Hestad M, Fehniger TE and Dirksen A. Identification of patients with chronic obstructive pulmonary disease (COPD) by measurement of plasma biomarkers. The Clinical Respiratory Journal 2008; 2: 17–25.
Impact of home mechanical ventilation on health‐related quality of life in patients with chronic alveolar hypoventilation: a prospective study
Authors: Dellborg Catharina , Olofson Jan , Midgren Bengt , Caro Oscar , Bergman Bengt , Skoogh Bengt‐Eric , Sullivan Marianne
Published: October 2007

Background:  Nocturnal ventilatory support by nasal positive pressure ventilation (NPPV) is an established treatment method in patients with chronic alveolar hypoventilation (CAH). The knowledge about its long‐term effects on health‐related quality of life (HRQL) is limited.

Methods:  In a prospective, longitudinal, single‐strand study, patients with CAH caused by non‐COPD conditions, consecutively recruited among referral patients in three Swedish university hospital pulmonary departments, were examined at baseline and after 9 months (n = 35) and 8 years (n = 11) on NPPV treatment. Both volume pre‐set and pressure pre‐set ventilators were used. Patients completed a battery of condition‐specific and generic HRQL questionnaires at baseline and follow‐up. Spirometry and blood gases were measured. Compliance with treatment, side effects and patient satisfaction were evaluated.

Results:  After 9 months of NPPV, improvements were seen primarily not only in sleep‐related domains, but also in emotional behaviour, ambulation and sleep/rest functioning as measured with the Sickness Impact Profile (SIP). Improvements in sleep‐related symptoms were related to effectiveness in ventilation, evaluated by morning PaCO2, and remained by 8 years. Mental well‐being was stable over time, while emotional distress improved by 8 years. Satisfaction with treatment was high in spite of frequent side effects.

Conclusion:  NPPV improves HRQL, particularly in condition‐specific areas. Improvements are related to effectiveness in ventilation. Side effects are common, but compliance is good and patient satisfaction is high.

Please cite this paper as: Dellborg C, Olofson J, Midgren B, Caro O, Bergman B, Skoogh B‐E and Sullivan M. Impact of home mechanical ventilation on health‐related quality of life in patients with chronic alveolar hypoventilation: a prospective study. The Clinical Respiratory Journal 2008; 2: 26–35.
Experimental hyperthyroidism increases expression of parathyroid hormone‐related peptide and type‐1 parathyroid hormone receptor in rat ventricular myocardium of the Langendorff ischaemia–reperfusion model
Authors: Halapas Antonios , Lembessis Peter , Mourouzis Iordanis , Pantos Costas , Cokkinos Dennis V. , Sourla Antigone , Koutsilieris Michael
Published: October 2007

Parathyroid hormone‐related peptide (PTHrP) is released under ischaemic conditions and it improves contractile function of stunned myocardium. The actions of PTHrP are mediated primarily by the type 1 parathyroid hormone receptor (PTH.1R), while PTHrP and PTH.1R expression levels are increased in ventricular hypertrophy associated with experimental hyperthyroidism. Since chronic administration of thyroxine (T4) improves postischaemic recovery in isolated heart models subjected to ischaemia–reperfusion stress, we tested the hypothesis that experimentally induced hyperthyroidism is associated with elevated expression of PTHrP and PTH.1R in rat myocardium. Hyperthyroid and control male Wistar rats were subjected to ischaemia–reperfusion stress using the Langendorff technique, and the PTHrP and PTH.1R expression was assessed by relative quantitative reverse transcriptase‐polymerase chain reaction, Western blot analysis and immunohistochemistry. In the Langendorff model, the recovery of left ventricular developed pressure at the end of the stablization period and 45 min into the reperfusion period was used to assess the cardioprotective actions of T4 administration. Our data show that hyperthyroid animals had increased tolerance to the ischaemia–reperfusion stress and that this was associated with an increase of PTHrP and PTH.1R expression levels compared with those of control animals. In the control animals, the expression of PTHrP was increased 45 min into the reperfusion phase, while the PTH.1R expression pattern was significantly and gradually decreased throughout the ischaemia and reperfusion phases. In the hyperthyroid animals, the PTHrP and PTH.1R expression pattern was significantly higher throughout the ischaemia and reperfusion phases compared with that of control hearts. Our data suggest that increasing levels of PTHrP and PTH.1R expression can mediate, at least in part, the T4 administration‐induced cardioprotection in rat ventricular myocardium.
Effects of hydralazine on the pulmonary vasculature and respiratory control in humans
Authors: Liu Chun , Balanos George M. , Fatemian Marzieh , Smith Thomas G. , Dorrington Keith L. , Robbins Peter A.
Published: October 2007

This study sought: (1) to clarify the effects of hydralazine on both the pulmonary vasculature and respiratory control in euoxia and hypoxia in healthy humans; and (2) to determine whether hydralazine alters the expression of genes regulated by hypoxia‐inducible factor 1 (HIF‐1). Ten volunteers participated in two 2 day protocols. Hydralazine (25 mg) or placebo was administered at 1 pm and 11 pm on the first day, and at 1 pm on the second day. In the mornings and afternoons of both days, we measured plasma vascular endothelial growth factor (VEGF) and erythropoietin (EPO) concentrations (both HIF‐1‐regulated gene products), systemic arterial blood pressure, and changes in heart rate, cardiac output, maximal systolic pressure difference across the tricuspid valve (ΔPmax) and ventilation in response to 20 min of isocapnic hypoxia. Recent hydralazine: (1) decreased diastolic blood pressure; (2) increased heart rate and cardiac output in euoxia and hypoxia whilst having no effect on ΔPmax; and (3) increased the ventilatory sensitivity to hypoxia. Hydralazine had no effect on plasma EPO or VEGF concentration. We conclude that hydralazine increases the sensitivity of the ventilatory response to hypoxia, but lacks any effect on the pulmonary vasculature at the dose studied. It did not affect the expression of HIF‐1‐regulated genes.
Renal calcium stones: insights from the control of bone mineralization
Authors: Moochhala S. H. , Sayer J. A. , Carr G. , Simmons N. L.
Published: October 2007

Extracellular pyrophosphate (PPi) plays a central role in the control of normal bone mineralization since it antagonizes inorganic phosphate in the promotion of hydroxyapatite deposition. Studies using knock‐out mice have established the functional importance of PPi generation via nucleotide pyrophosphatase phosphodiesterases (NPP) and of PPi transmembrane transport by the progressive ankylosis (ANK) protein. Tissue non‐specific alkaline phosphatase activity counteracts this by hydrolysis of PPi to inorganic phosphate. The molecular nature and transport function of ANK are reviewed. A close parallel is drawn between the controlled mineralization of bone and the prevention of abnormal calcium crystal deposition within the kidney, especially when concentrated urine is produced. Pyrophosphate is present in urine, and ANK is expressed in the cortical collecting duct where PPi transport to both the tubular lumen and the renal interstitium may occur. Pyrophosphate may also be generated here by nucleoside triphosphate diphosphohydrolases (NTPD2 and 3) together with NPP1. Alkaline phosphatase activity is restricted to the proximal nephron, remote from these sites of PPi generation, transport and function. The physiological importance of PPi generation and transport in preventing idiopathic calcium renal stone disease and nephrocalcinosis now needs to be established.
Postnatal development of synaptic transmission in local networks of L5A pyramidal neurons in rat somatosensory cortex
Authors: Frick Andreas , Feldmeyer Dirk , Sakmann Bert
Published: October 2007

The probability of synaptic transmitter release determines the spread of excitation and the possible range of computations at unitary connections. To investigate whether synaptic properties between neocortical pyramidal neurons change during the assembly period of cortical circuits, whole‐cell voltage recordings were made simultaneously from two layer 5A (L5A) pyramidal neurons within the cortical columns of rat barrel cortex. We found that synaptic transmission between L5A pyramidal neurons is very reliable between 2 and 3 weeks of postnatal development with a mean unitary EPSP amplitude of ∼1.2 mV, but becomes less efficient and fails more frequently in the more mature cortex of ∼4 weeks of age with a mean unitary EPSP amplitude of 0.65 mV. Coefficient of variation and failure rate increase as the unitary EPSP amplitude decreases during development. The paired‐pulse ratio (PPR) of synaptic efficacy at 10 Hz changes from 0.7 to 1.04. Despite the overall increase in PPR, short‐term plasticity displays a large variability at 4 weeks, ranging from strong depression to strong facilitation (PPR, range 0.6–2.1), suggesting the potential for use‐dependent modifications at this intracortical synapse. In conclusion, the transmitter release probability at the L5A–L5A connection is developmentally regulated in such a way that in juvenile animals excitation by single action potentials is efficiently transmitted, whereas in the more mature cortex synapses might be endowed with a diversity of filtering characteristics.
Force generation examined by laser temperature‐jumps in shortening and lengthening mammalian (rabbit psoas) muscle fibres
Authors: Ranatunga K. W. , Coupland M. E. , Pinniger G. J. , Roots H. , Offer G. W.
Published: October 2007

We examined the tension change induced by a rapid temperature jump (T‐jump) in shortening and lengthening active muscle fibres. Experiments were done on segments of permeabilized single fibres (length (L0) ∼2 mm, sarcomere length 2.5 μm) from rabbit psoas muscle; [MgATP] was 4.6 mm, pH 7.1, ionic strength 200 mm and temperature ∼9°C. A fibre was maximally Ca2+‐activated in the isometric state and a ∼3°C, rapid (< 0.2 ms), laser T‐jump applied when the tension was approximately steady in the isometric state, or during ramp shortening or ramp lengthening at a limited range of velocities (0–0.2 L0 s−1). The tension increased to 2‐ to 3 ×P0 (isometric force) during ramp lengthening at velocities > 0.05 L0 s−1, whereas the tension decreased to about < 0.5 ×P0 during shortening at 0.1–0.2 L0 s−1; the unloaded shortening velocity was ∼1 L0 s−1 and the curvature of the force–shortening velocity relation was high (a/P0 ratio from Hill's equation of ∼0.05). In isometric state, a T‐jump induced a tension rise of 15–20% to a new steady state; by curve fitting, the tension rise could be resolved into a fast (phase 2b, 40–50 s−1) and a slow (phase 3, 5–10 s−1) exponential component (as previously reported). During steady lengthening, a T‐jump induced a small instantaneous drop in tension, followed by recovery, so that the final tension recorded with and without a T‐jump was not significantly different; thus, a T‐jump did not lead to a net increase of tension. During steady shortening, the T‐jump induced a pronounced tension rise and both its amplitude and the rate (from a single exponential fit) increased with shortening velocity; at 0.1–0.2 L0 s−1, the extent of fibre shortening during the T‐jump tension rise was estimated to be ∼1.2%L0 and it was shorter at lower velocities. At a given shortening velocity and over the temperature range of 8–30°C, the rate of T‐jump tension rise increased with warming (Q10≈ 2.7), similar to phase 2b (endothermic force generation) in isometric muscle. Results are discussed in relation to the previous findings in isometric muscle fibres which showed that a T‐jump promotes an early step in the crossbridge–ATPase cycle that generates force. In general, the finding that the T‐jump effect on active muscle tension is pronounced during shortening, but is depressed/inhibited during lengthening, is consistent with the expectations from the Fenn effect that energy liberation (and acto‐myosin ATPase rate) in muscle are increased during shortening and depressed/inhibited during lengthening.
Free-Edge Effects in Composite Laminates
Authors: Mittelstedt Christian , Becker Wilfried
Published: October 2007

There are many technical applications in the field of lightweight construction as, for example, in aerospace engineering, where stress concentration phenomena play an important role in the design of layered structural elements (so-called laminates) consisting of plies of fiber reinforced plastics or other materials. A well known stress concentration problem rich in research tradition is the so-called free-edge effect. Mainly explained by the mismatch of the elastic material properties between two adjacent dissimilar laminate layers, the free-edge effect is characterized by the concentrated occurrence of three-dimensional and singular stress fields at the free edges in the interfaces between two layers of composite laminates. In the present contribution, a survey on relevant literature from more than three decades of scientific research on free-edge effects is given. The cited references date back to 1967 and deal with approximate closed-form analyses, as well as numerical investigations by the finite element method, the finite difference method, and several other numerical techniques. The progress in research on the stress singularities which arise is also reviewed, and references on experimental investigations are cited. Related problems are also briefly addressed. The paper closes with concluding remarks and an outlook on future investigations. In all, 292 references are included.
Interaction of Ships and Ocean Structures With Ice Loads and Stochastic Ocean Waves
Authors: Ibrahim R. A. , Chalhoub N. G. , Falzarano Jeffery
Published: October 2007

The influence of floating ice on the dynamic behavior of ships and offshore structures depends on many factors such as ice thickness and its relative speed with respect to the floating structure. The ice resistance to ship motion forms an essential problem in ship design and navigation. Furthermore, local or global ice loads acting on ocean systems are random and nonsmooth when impact interaction takes place. Impact loads on the bow of a ship navigating in solid ice may be modeled by a Poisson law. The measured stress amplitudes on the ship frame at the bow follow an exponential distribution. The nonhomogeneity and difference in ice microstructure, as well as the influence of salt and temperature, result in a great uncertainty in the ice strength. Therefore, the current review article aims at assessing the ice related problems encountered by offshore structures as well as by ships during their navigation. It also discusses the impacts of local and global ice loads on floating structures and reviews their existing probabilistic models. Moreover, this article covers the dynamic interaction of ice with flexible and rigid structures, and ships. In view of ice loads on marine systems, new design regulations have been introduced by international organizations that are involved in the design and building of ships as well as offshore structures. The ship stochastic stability and the first-passage roll stabilization problem associated with random ocean waves will also be described in an attempt to stimulate future research work dealing with ice impact loads. Moreover, due to the lack of research activities addressing the control problem of ships operating in icy waters, the current article will briefly discuss passive and active control schemes developed for controlling the ship roll motion. There are 529 references cited in this review article.
Fabrication of magnetic force microscopy probes via localized electrochemical deposition of cobalt
Authors: Rolandi Marco , Okawa David , Backer Scott A. , Zettl Alex , Fréchet Jean M. J.
Published: October 2007

Magnetic force microscopy probes were obtained via the solution phase electrochemical deposition of cobalt nanostructures at the probe apexes. Single tips were fabricated in an atomic force microscope fluid cell. Multiple tips were produced in a single batch with an alternating potential in an electrochemical cell. The probes achieve 50nm spatial resolution.
Optimized fabrication of silicon nanofocusing x-ray lenses using deep reactive ion etching
Authors: Kurapova O. , Lengeler B. , Schroer C. G. , Küchler M. , Gessner T. , van der Hart A.
Published: October 2007

The authors describe an improved production route for silicon nanofocusing lenses for hard x rays using e-beam lithography and deep reactive ion etching. As compared to previous prototypes, these optics have a significantly improved from fidelity, reducing spherical aberrations. Close to an ideal performance for the focusing of hard x rays is achieved with these optics, reaching a lateral beam size of about 50nm. The lens profile is checked by scanning electron microscopy.
Effect of MgO coating on field emission of a stand-alone carbon nanotube
Authors: Pan Lujun , Konishi Yasumoto , Tanaka Hiroyuki , Chakrabarti Supriya , Hokushin Shogo , Akita Seiji , Nakayama Yoshikazu
Published: October 2007

Field emission properties of a stand-alone MgO-coated carbon nanotube (CNT) have been investigated by a field emission microscopy. A finite element method is used to analyze the electric field distribution on the surface of a CNT and in the layer of MgO. It is found that the dielectric MgO layer decreases the strength of electric field on the CNT surface and then increases the tunnel barrier of field emission. However, it is observed that the MgO coating largely decreases the fluctuation of the emission current from a CNT especially in the current of over 10−7A.
Carbon nanotube tip melting with vacuum breakdown in cold cathode
Authors: Verma P. , Gautam S. , Kumar P. , Chaturvedi P. , Rawat J. S. , Pal S. , Chaubey R. , Harsh  , Vyas H. P. , Bhatnagar P. K.
Published: October 2007

Failure of patterned multiwalled carbon nanotubes during field emission (FE) was systematically studied at different fields using an indigenous FE setup. Here, the findings are reported from the experimental observation of the degradation of carbon nanotube (CNT) based field emitters over a silicon substrate. The CNTs were grown on the patterned silicon substrate using chemical vapor deposition (CVD) and plasma-enhanced CVD (PECVD) techniques. Scanning electron microscopy (SEM) was employed to observe the effect of different fields over CNTs. The observed current density of 28mA∕cm2 at a field of 5V∕μm from CNTs grown via CVD before giving a high-field treatment remained almost the same until the substrate started melting. Similar observations were made in CNTs grown via PECVD. SEM images clearly reveal that the high-field treatment resulted in melting of silicon substrate at a certain point; at some other points, etching of silicon substrate was also observed. The authors attribute these observations to arcing because the base vacuum was not sufficiently adequate for the applied field. Due to arcing, the localized temperature became so high that the substrate started to melt. The SEM images give an insight into understanding the degradation mechanism of CNT-based field emitters.
Effects of pore morphology on the diffusive properties of a porous low-κ dielectric
Authors: Joseph E. A. , Sant S. P. , Goeckner M. J. , Overzet L. J. , Peng H. G. , Gidley D. W. , Kastenmeier B. E. E.
Published: October 2007

Porous methylsilsesquioxane-based spin-on films with pore sizes of 1.5–2nm and porosities ranging from 0% to 32% have been exposed to a variety of processing environments such as fluorocarbon or oxygen containing plasmas and TaN atomic layer deposition to determine the integratability of the films. The porosity of the low-κ films was found to decrease during processing due to tantalum and fluorine indiffusion (fluorine potentially depositing as fluorocarbon film in the pores) while oxygen indiffusion depleted carbon (possibly by forming volatile CO and CO2). Carbon removal from the low-κ film alters the film’s dielectric constant and refractive index. The depth of the indiffusion appears to be independent of diffusant (fluorocarbon, oxygen, or tantalum), ranging from 40to150nm, and to correlate directly to the pore structure. It was also found that water (moisture) in these films significantly affects the measured porosity as well as can be used to reduce the indiffusion of fluorine containing molecules by a factor of 2. The diffusivity of various molecules in the low-κ films was estimated by using a Deal-Grove model and found to increase linearly with porosity (ranging from 1×10−8to1.6×10−7cm2∕s) while the “reaction” rate constant was found to increase nonlinearly with porosity (ranging from 4×10−6to2.3×10−5cm∕s).
Experimental and model-based study of the robustness of line-edge roughness metric extraction in the presence of noise
Authors: Naulleau Patrick P. , Cain Jason P.
Published: October 2007

As critical dimensions shrink, line edge roughness (LER) and linewidth roughness (LWR) become of increasing concern. Crucial to the goal of reducing LER is its accurate characterization. LER has traditionally been represented as a single rms value. More recently, the use of power spectral density (PSD), height-height correlation (HHCF), and σ versus length plots has been proposed in order to extract the additional spatial descriptors of correlation length and roughness exponent. Here, the authors perform a modeling-based noise-sensitivity study on the extraction of spatial descriptors from line-edge data as well as an experimental study of the robustness of these various descriptors using a large data set of recent extreme-ultraviolet exposure data. The results show that in the presence of noise and in the large data set limit, the PSD method provides higher accuracy in the extraction of the roughness exponent, whereas the HHCF method provides higher accuracy for the correlation length. On the other hand, when considering precision, the HHCF method is superior for both metrics.
Enhancement on forming complex three dimensional microstructures by a double-side multiple partial exposure method
Authors: Chung Junwei , Hsu Wensyang
Published: October 2007

This study presents a novel batch process based on standard lithography technology, called the double-side multiple partial exposure (DoMPE) method, which enhances the fabrication capability of three dimensional (3D) photoresist microstructures. By incorporating gray-tone lithography and double-side exposure techniques, the proposed DoMPE scheme extends the multilevel morphology on both the front side and back side of the suspended photoresist microstructures. Back-side gray-tone lithography is achieved by depositing various appropriate thicknesses of Ti film on glass substrate that acts as the gray-tone mask. The process parameters, including metal film thickness, developed depth, exposure dosage, development time, and soft-bake time, are experimentally characterized. Different 3D photoresist microstructures with multiple levels on the front and back sides are successfully fabricated and presented here to show the enhancement effect using the proposed technique, including a microinductor structure and a vertical comb drive structure that demonstrate potential applications even on electrically conductive devices.
High performance GaAsSb∕GaAs quantum well lasers
Authors: Yu S.-Q. , Ding D. , Wang J.-B. , Samal N. , Jin X. , Cao Y. , Johnson S. R. , Zhang Y.-H.
Published: October 2007

Ga As Sb ∕ Ga As quantum wells (QWs) with 1.3μm light emission are grown using solid-source molecular beam epitaxy. The growth temperature is optimized based on photoluminescence (PL) linewidth and intensity and edge-emitting laser (EEL) threshold current density; these measurements concur that the optimal growth temperature is ∼490°C (∼500°C) for GaAsSb∕GaAs QWs grown with (without) GaAsP strain compensation. High performance EELs and vertical-cavity surface-emitting lasers (VCSELs) are demonstrated using the GaAsSb∕GaAs∕GaAsP strain compensated active region. One EEL achieved an output power up to 0.9W with thresholds as low as 356A∕cm2 under room temperature pulsed operation, while another achieved continuous-wave (cw) operation at temperatures up to 48°C for wavelengths as long as 1260nm. A set of VCSELs achieved room temperature cw operation with output powers from 0.03to0.2mW and lasing wavelengths from 1240to1290nm. The temperature characteristics of these devices indicate that the optimal gain-peak cavity-mode tuning for pulsed operation specifies a room temperature PL peak redshift of 20–30nm relative to the cavity mode.
Ultrahigh vacuum scanning tunneling microscope manipulation of single gold nanoislands on MoS2 for constructing planar nanointerconnects
Authors: Yang Jianshu , Deng Jie , Chandrasekhar N. , Joachim C.
Published: October 2007

The manipulation of single metallic nanoislands with a precision better than 0.5nm on a MoS2 surface is demonstrated. Optimizing the metal growth conditions yields triangular-shaped nanoislands of 30nm in lateral size and 12nm in height on the MoS2 surface. The manipulation of a single nanoisland was performed using the tip apex of a scanning tunneling microscope. The feedback loop conditions to achieve this manipulation are discussed. Fully planar four-pad nanostructures were constructed, and the apex of each triangular nanoisland of the nanostructure is pointing toward a central 10×20nm2 MoS2 working area where the surface atomic cleanliness is preserved.
Tribochemistry and material transfer for the ultrananocrystalline diamond-silicon nitride interface revealed by x-ray photoelectron emission spectromicroscopy
Authors: Grierson David S. , Sumant Anirudha V. , Konicek Andrew R. , Abrecht Mike , Birrell J. , Auciello Orlando , Carlisle John A. , Scharf Thomas W. , Dugger Michael T. , Gilbert P. U. P. A. , Carpick Robert W.
Published: October 2007

The authors report tribochemical changes due to sliding of a silicon nitride (Si3N4) ball against an ultrananocrystalline diamond (UNCD) thin film. Unidirectional sliding wear measurements were conducted for 2000cycles using a ball-on-disk apparatus with a 3∕16in. diameter Si3N4 ball at a sliding speed of 3.3mm∕s and a normal load of 98.0mN (nominal Hertzian stress of 0.6GPa) in a nitrogen environment at 50% relative humidity at room temperature. The wear track produced on the UNCD film was analyzed by X-ray photoelectron emission spectromicroscopy (X-PEEM) combined with X-ray absorption near-edge structure (XANES) spectroscopy to identify and spatially resolve chemical changes inside the wear track, particularly rehybridization of carbon. XANES spectra show that SiOx complexes are deposited within the wear track. Very little rehybridization of the UNCD from its primarily sp3 bonding configuration to sp2 bonding is observed, and there is no observable oxidation of the UNCD, pointing to the impressive stability of the film under significant tribological loading conditions. Raman spectroscopy of the worn portion of the Si3N4 ball shows that disordered carbon is found on the worn surface. The authors attribute the formation of SiOx complexes within the wear track to wear of the ball and subsequent deposition into the track. The authors attribute the disordered carbon on the Si3N4 ball to removal of sp2-bonded carbon from the UNCD surface and subsequent accumulation onto the ball’s surface. This work demonstrates the potential of X-PEEM for the study of tribochemical modifications of carbon-based thin film surfaces.
Preparation of ferrite-coated magnetic force microscopy cantilevers
Authors: Kirsch M. , Koblischka M. R. , Wei J. D. , Hartmann U.
Published: October 2007

Thin films of two types of ferrites, NiZnFe2O4 spinel ferrite and Co2 Z-type hexaferrite (Ba3Co2Fe24O41) were prepared by rf sputtering on Si (1 0 0) and (1 1 1) substrates. Films with a thickness up to 100nm were prepared for analysis purposes, enabling the optimization of the sputter process. The purpose of these ferrite thin films is the preparation of magnetic force microscopy (MFM) cantilever coatings for use with a high-frequency magnetic force microscope (HF-MFM). As a basis for these probes, the authors employ commercial, micromachined silicon cantilevers. The typical thickness of the coatings was 50nm. The MFM imaging properties of both types of ferrite-coated cantilevers are discussed in detail.
Controlling pressure in microsystem packages by on-chip microdischarges between thin-film titanium electrodes
Authors: Wright Scott A. , Gianchandani Yogesh B.
Published: October 2007

This article describes on-chip sputter-ion pumps and their use in the controlled reduction of pressure in large cavity packages. The devices utilize thin-film titanium electrodes patterned on glass substrates and exposed to the cavity environments. Microdischarges between the electrodes sputter the cathodes, resulting in the selective chemisorption of oxygen, nitrogen, and other titanium-reactive gases. dc and pulsed high voltage powering schemes are investigated. Using dc discharges, devices on a 1cm2 footprint remove 168Torr of air from a hermetically sealed commercial package with a volume of 6.33cm3. Starting at 200Torr, the removal rate of air is 7.2Torr∕h; for oxygen it is 11.5Torr∕h and for nitrogen 3.4Torr∕h. The relative humidity is reduced 6%∕h, starting with 61%. The pumps have been shown not to remove helium from the environment. A 5× increase in pump power efficiency is obtained through the use of 25ms pulsed discharges as opposed to dc discharges. The gas removal rates also depend on both initial pressure and discharge gap spacing. A theoretical model outlining the dependency of gas removal rates on microdischarge parameters is reported.
In vivo dosimetry for estimation of effective doses in multislice CT coronary angiography
Authors: de Denaro M. , Bregant P. , Severgnini M. , de Guarrini F.
Published: October 2007

In vivo dosimetry represents a technique that has been widely employed to evaluate the dose to the patient mainly in radiotherapy. Considering the increment in dose to the population due to new high‐dose multislice CT examinations, such as coronary angiography, it is becoming important to more accurately know the dose to the patient. The desire to know patient dose extends even to radiological examinations. Thermoluminescent dosimeters are considered the gold standard for in vivo dosimetry, but their use is time consuming. A rapid, less labor‐intensive method has been developed to perform in vivo dosimetry using radiochromic film positioned next to the patient's skin. Multislice CT scanners allow the estimation of the effective dose to the patient from the dose length product (DLP) parameter, the value of which is displayed on the acquisition console, simply multiplying the DLP by published conversion factors. The method represents only an approximation based on standard size circular phantoms and neglects the actual size of the patient. More accurate evaluations can be carried out using software‐based Monte Carlo simulations. However, these methods do not consider possible dose reduction techniques, such as automatic tube‐current modulation. For 22 patients effective doses measured by in vivo dosimetry and calculated by software were compared. The technique of using in vivo dosimetry measured with radiochromic film appears a promising procedure for improving the assessment of the effective dose to the patient.
Accurate quantification of width and density of bone structures by computed tomography
Authors: Hangartner Thomas N. , Short David F.
Published: October 2007

In computed tomography (CT), the representation of edges between objects of different densities is influenced by the limited spatial resolution of the scanner. This results in the misrepresentation of density of narrow objects, leading to errors of up to and more. Our interest is in the imaging and measurement of narrow bone structures, and the issues are the same for imaging with clinical CT scanners, peripheral quantitative CT scanners or micro CT scanners. Mathematical models, phantoms and tests with patient data led to the following procedures: (i) extract density profiles at one‐degree increments from the CT images at right angles to the bone boundary; (ii) consider the outer and inner edge of each profile separately due to different adjacent soft tissues; (iii) measure the width of each profile based on a threshold at fixed percentage of the difference between the soft‐tissue value and a first approximated bone value; (iv) correct the underlying material density of bone for each profile based on the measured width with the help of the density‐versus‐width curve obtained from computer simulations and phantom measurements. This latter curve is specific to a certain scanner and is not dependent on the densities of the tissues within the range seen in patients. This procedure allows the calculation of the material density of bone. Based on phantom measurements, we estimate the density error to be below relative to the density of normal bone and the bone‐width error about one tenth of a pixel size.
Experimental measurement of radiological penumbra associated with intermediate energy x‐rays and small radiosurgery field sizes
Authors: Keller Brian M. , Beachey David J. , Pignol Jean‐Philippe
Published: October 2007

Stereotactic radiosurgery is used to treat intracranial lesions with a high degree of accuracy. At the present time, x‐ray energies at or above Co‐60 gamma rays are used. Previous Monte Carlo simulations have demonstrated that intermediate energy x‐ray photons or IEPs (defined to be photons in the energy range of ), combined with small field sizes, produce a reduced radiological penumbra leading to a sharper dose gradient, improved dose homogeneity and sparing of critical anatomy adjacent to the target volume. This hypothesis is based on the fact that, for small x‐ray fields, a dose outside the treatment volume is dictated mainly by the range of electrons set into motion by x‐ray photons. The purpose of this work is: (1) to produce intermediate energy x rays using a detuned medical linear accelerator, (2) to characterize the energy of this beam, (3) to measure the radiological penumbra for IEPs and small fields to compare with that produced by x rays or Co‐60, and (4) to compare these experimental measurements with Monte Carlo computer simulations. The maximum photon energy of our IEP x‐ray spectrum was measured to be . Gafchromic EBT films (ISP Technologies, Wayne, NJ) were irradiated and read using a novel digital microscopy imaging system with high spatial resolution. Under identical irradiation conditions the measured radiological penumbra widths (80%–20% distance), for field sizes ranging from , varied from and from . Even more dramatic were the differences found when comparing the 90%–10% or the 95%–5% widths, which are in fact more significant in radiotherapy. Monte Carlo simulations agreed well with the experimental findings. The reduction in radiological penumbra could be substantial for specific clinical situations such as in the treatment of an ocular melanoma abutting the macula or for the treatment of functional disorders such as trigeminal neuralgia (a nonlethal neurological pathology) where no long‐term side effect should be induced by the treatment.