bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prevalence of Malaria and Helicobacter Pylori Coinfection and Associated Sociodemographic Factors among Blood Donors in Douala General Hospital
Authors: Djakissam Watching , Agberndifor Thelma Epole , Honoré Ndouwe Tissebe Menga , Nzegge Ebude Roda , Elisabeth Zeuko’o Menkem , Lavoisier Yimtchi Ngassa Christian , Baiye Abange William , Mengue Emmanuel Rode 
Published: April 2024

Background: The malaria parasite Plasmodium is intra-erythrocyte hence can be transmitted by transfusion of any blood component containing infected red blood cells. Helicobacter pylori infection affects more than half of the human population worldwide. Infection remains asymptomatic in most individuals, although some individuals develop acute gastritis, peptic or duodenal ulcers, gastric cancer, and mucosa associated tissue lymphoma. H. pylori infection have been implicated in some haematological manifestations such as anaemia and micronutrient deficiency.
Objective: This research was designed to determine the prevalence of malaria parasitaemia and H. pylori coinfection in association with sociodemographic characteristics among donors in Douala General Hospital.
Methodology: The study was a hospital-based study carried out from January to May 2022. The study population comprised of 106 donors who came to the hospital laboratory for blood donation. A structured questionnaire was used to get demographic and clinical data. Two ml of blood was collected from individuals to prepare a thick and thin blood film for malaria parasite determination and to centrifuge at 3000 rpm for 5 minutes to obtain plasma for H. pylori test strip.
Results and Discussion: The overall prevalence of H. pylori in the study area was 70.8%. The female donors had a prevalence of 72.0%. A greater proportion of blood group O donors had H. pylori than groups A, AB and B but this difference was not significant (P-value = 0.571). The prevalence of malaria parasites infection was 36.8%. Those of blood group A had a higher prevalence rate of 42.3% (11/26). Out of the 106 donors, 23 (21.7%) had malaria and H. pylori coinfection. 68 (64.2%) donors had a mono-infection that is either having malaria mono-infection or H. pylori mono-infection and 15 (14.2%) had no infection. Malaria and H. pylori coinfection was higher in female donors than males (OR = 1.059, 95% Cl 0.359 -3.119, P =0.917), in donors aged below 25 years old (OR = 0.338, 95% Cl 0.075 - 1.535, P =0.160), replacement donors (OR = 1.350, 95% Cl 0.460 – 3.964, P =0.585); blood donors of blood group AB (OR = 0.654, 95% Cl 0.181 – 2.366, P =0.517) and Rhesus negative donors (OR = 1.500, 95% Cl 0.130 – 17.36, P =0.746).
Conclusion: The prevalence of H. pylori infection and Malaria among blood donors in Douala General Hospital were high and coinfection was higher in females than males. Both malaria parasites and H. pylori infections have been implicated in blood parameters such as anaemia and micronutrient deficiency. It is therefore recommended that routine screening for malaria parasites and H. pylori be done in blood banks before transfusion for a high blood quality.
Colours and Metallic Sheen in Beetle Shells — A Biomimetic Search for Material Structuring Principles Causing Light Interference
Authors: Lenau T. , Barfoed M. 
Published: April 2008

AbstractVisual aesthetic has always played a vital role for the success of many products. This includes colours and glossiness and metal appearance which is often achieved using surface coatings. Present coating techniques do, however, have limitations. It is difficult to reach very bright and brilliant colours, colours tend to fade over time and many of the materials and coating technologies pollute and have other environmental problems. Beetles in nature have many of the desired properties: They have appealing brilliant colours and some even with metallic appearance. It is noticeable that the colours are long lasting as some of the beetles we have studied at the zoological museum are more than 200 years old and have colours and brightness as if they were still alive. Furthermore, the beetles in nature are part of sustainable ecosystems, which means that they are made from renewable materials that are broken down and recycled when the beetle dies. Beetles also possess another and very attractive property: Their metallic look originates from structures in organic materials which is both electrically and thermal insulating. The industrial perspective is to be able to manufacture products with attractive metallic surfaces that do not feel so cold to touch as their metallic counterparts and that do not represent an electrical shock hazard.
Fracture of Ceramics
Authors: Danzer R. , Lube T. , Supancic P. , Damani R. 
Published: April 2008

AbstractThe paper reviews the current state of art of the fracture of brittle ceramic materials. Typical loading situations (thermal shock, contact damage) are analysed and the resulting fracture modes are discussed. In focus of the paper are the brittle fracture and the resulting probabilistic aspects. The delayed failure of brittle materials (sub critical crack growth and cyclic fatigue) is also discussed.
Simulation of Deformation, Damage and Residual Stresses in Arterial Walls
Authors: Balzani D. 
Published: April 2008

AbstractThe numerical simulation of arterial walls is important for analyzing what happens during balloon‐angioplasty and may help to optimize methods of treatment. A variety of suitable material models exist for the description of deformations in the physiological domain which also satisfy some important mathematical conditions such as polyconvexity or ellipticity. In addition there are approaches to model residual stresses and anisotropic damage due to supra‐physiological deformations. In this contribution an extended damage model is proposed for the incorporation of softening hysteresis observed in cyclic supra‐physiological uniaxial tension tests. Furthermore, numerical results are given, where the distribution of damage due to overstretching an atherosclerotic artery can be analyzed.
Cover Picture: Directional Atomic Rearrangements During Transformations Between the α‐ and γ‐Phases in Titanium Aluminides (Adv. Eng. Mater. 4/2008)
Authors: Liss K.‐D. , Stark A. , Bartels A. , Clemens H. , Buslaps T. , Phelan D. , Yeoh L. A. 
Published: April 2008

AbstractMaking movies in‐situ at glowing temperatures up to 1300 °C through a microscope (false color image) and from two‐dimensional X‐ray diffraction (movie frames) reveal the lattice correlations, gradients and intermediate structures during phase transformations in titanium aluminide. A quenched, α2‐rich γ‐based TiAl first approaches its equilibrium by α2 → γ on a heating ramp, disorders α2 → α and then evolves reversely γ → α, which are morphologically different processes. More details can be found in the article by K.‐D. Liss et al. on page 389.
Controlled Synthesis of Ag2S, Ag2Se, and Ag Nanofibers by Using a General Sacrificial Template and Their Application in Electronic Device Fabrication
Authors: Wang Hailiang , Qi Limin 
Published: April 2008

AbstractNanofiber bundles of Ag2S, Ag2Se, and Ag have been successfully synthesized by making use of Ag2C2O4 template nanofiber bundles, utilizing both anion‐exchange and redox reactions. The obtained bundles were polycrystalline nanofibers composed of nanoparticles in which the precursor morphology was well‐preserved, indicating that Ag2C2O4 nanofiber bundles acted as a general sacrificial template for the synthesis of silver‐based semiconductor and metal nanofibers. Dispersing media and transforming reactants were found to be key factors influencing the chemical transformation in the system. In particular, separate single‐crystalline Ag nanofibers were obtained via a nontemplate route when ascorbic acid was used as a relatively weak reductant. An electrical transfer and switching device was built with the obtained Ag2S and Ag nanofiber bundles, utilizing the unique ion‐conductor nature of Ag2S and revealing their potential applications in electronics.
Effects of Arylene Diimide Thin Film Growth Conditions on n‐Channel OFET Performance
Authors: Jones Brooks A. , Facchetti Antonio , Wasielewski Michael R. , Marks Tobin J. 
Published: April 2008

AbstractA series of eight perylene diimide (PDI)‐ and naphthalene diimide (NDI)‐based organic semiconductors was used to fabricate organic field‐effect transistors (OFETs) on bare SiO2 substrates, with the substrate temperature during film deposition (Td) varied from 70–130 °C. For the N,N′‐n‐octyl materials that form highly ordered films, the mobility (µ) and current on‐off ratio (Ion/Ioff) increase slightly from 70 to 90 °C, and remain relatively constant between 90 and 130 °C. Ion/Ioff and µ of dibromo‐PDI‐based OFETs decrease with increasing Td, while films of N,N′‐1H,1H‐perfluorobutyl dicyanoperylenediimide (PDI‐FCN2) exhibit dramatic Ion/Ioff and µ enhancements with increasing Td. Increased OFET mobility can be correlated with higher levels of molecular ordering and minimization of film morphology surface irregularities. Additionally, the effects of SiO2 surface modification with trimethylsilyl and octadecyltrichlorosilyl monolayers, as well as with polystyrene, are investigated for N,N′‐n‐octyl dicyanoperylenediimide (PDI‐8CN2) and PDI‐FCN2 films deposited at Td = 130 °C. The SiO2 surface treatments have modest effects on PDI‐8CN2 OFET mobilities, but modulate the mobility and morphology of PDI‐FCN2 films substantially. Most importantly, the surface treatments result in substantially increased Vth and decreased Ioff values for the dicyanoperylenediimide films relative to those grown on SiO2, resulting in Vth > 0.0 V and Ion/Ioff ratios as high as 108. Enhancements in current modulation for these high‐mobility, air‐stable, and solution‐processable n‐type semiconductors, should prove useful in noise‐margin enhancement and further improvements in organic electronics.
The Gas‐Detection Properties of Light‐Emitting Diatoms
Authors: Lettieri Stefano , Setaro Antonio , De Stefano Luca , De Stefano Mario , Maddalena Pasqualino 
Published: April 2008

AbstractIn recent years, the porous silica structures (frustules) created by living diatoms have been studied for several nanoengineering applications based on biomimetic approaches. We focus on the gas‐sensing properties of diatoms: investigation of different species shows that the photoluminescence emission of frustules is affected by even small modifications of the surrounding gas environment, exhibiting a detection limit of few tenths of ppm in the case of nitrogen dioxide. A new understanding of this phenomenon is discussed here in terms of “static‐type” luminescence quenching through suppression of radiative states (most probably surface oxygen vacancies) induced by adsorption of gas molecules. The modeling allows the free energy of desorption to be measured by all‐optical means: the value obtained suggests that a chemisorption process is involved, in agreement with the observed absorption/desorption kinetics. The findings encourage investigation of diatoms as low‐cost biological transducers for detection of gas species.
Effects of Laminate Architecture on Fracture Resistance of Sponge Biosilica: Lessons from Nature
Authors: Miserez Ali , Weaver James C. , Thurner Philipp J. , Aizenberg Joanna , Dauphin Yannicke , Fratzl Peter , Morse Daniel E. , Zok Frank W. 
Published: April 2008

AbstractHexactinellid sponges are known for their ability to synthesize unusually long and highly flexible fibrous spicules, which serve as the building blocks of their skeletal systems. The spicules consist of a central core of monolithic hydrated silica, surrounded by alternating layers of hydrated silica and proteinaceous material. The principal objective of the present study is to ascertain the role of the latter laminate architecture in the material's resistance to both crack initiation and subsequent crack growth. This has been accomplished through indentation testing on the giant anchor spicule of Monorhaphis chuni, both in the laminated region and in the monolithic core, along with a theoretical analysis of deformation and cracking at indents. The latter suggests that the threshold load for crack initiation is proportional to Kc4/E2H where Kc is fracture toughness, E is Young's modulus, and H is hardness. Two key experimental results emerge. First, the load required to form well‐defined radial cracks from a sharp indent in the laminated region is two orders of magnitude greater than that for the monolithic material. Secondly, its fracture toughness is about 2.5 times that of the monolith, whereas the modulus and hardness are about 20% lower. Combining the latter property values with the theoretical analysis, the predicted increase in the threshold load is a factor of about 80, broadly consistent with the experimental measurements.
Swelling Behavior of Multiresponsive Poly(methacrylic acid)‐block‐‐poly(N‐isopropylacrylamide) Brushes Synthesized Using Surface‐Initiated Photoiniferter‐Mediated Photopolymerization
Authors: Rahane Santosh B. , Floyd J. Alaina , Metters Andrew T. , Kilbey S. Michael 
Published: April 2008

AbstractSurface‐initiated photoiniferter‐mediated photopolymerization (SI‐PMP) in presence of tetraethylthiuram disulfide is used to directly synthesize surface‐grafted poly(methacrylic acid)‐block‐poly(N‐isopropylacrylamide) (PMAA‐b‐PNIPAM) layers. The response of these PMAA‐b‐PNIPAM bi‐level brushes to changes in pH, temperature and ionic strength is investigated by using in‐situ multi‐angle ellipsometry to measure changes in solvated layer thickness. As expected for a block copolymer architecture, PMAA blocks swell as pH is increased, with the maximum change in the thickness occurring near pH = 5, and PNIPAM blocks exhibit lower critical solution temperature (LCST) behavior, marked by a broad transition between swollen and collapsed states. The response of the bi‐level brushes to changes in added salt at constant pH is complex, as the swelling behaviors of both the weak polyelectrolyte, PMAA, and thermoresponsive PNIPAM are affected by changes in ionic strength. This work demonstrates not only the robustness of SI‐PMP for making novel, bi‐level stimuli‐responsive brushes, but also the complex links between synthesis, structure, and response of these materials.
Gold(III) Chloride‐Catalyzed Diastereoselective Alkylation Reactions with Chiral Benzylic Acetates
Authors: Rubenbauer Philipp , Bach Thorsten 
Published: April 2008

AbstractGold(III) chloride was shown to be an efficient catalyst for the diastereoselective CC bond formation of various chiral para‐methoxybenzylic acetates and different nucleophiles. All electrophilic acetates carried next to the reacting center a stereogenic carbon center bound to a functional group (FG), a methyl substituent and a proton. Selectivities were good (dr>80/20) in favor of the anti‐product for FG=COOMe, NO2, CN and in favor of the syn‐product for FG=SO2Et, PO(OEt)2. The reactions proceed most likely via a free carbocation, in which a face differentation is facilitated by a preferred conformation. Several arene nucleophiles were shown to be compatible with the catalysis conditions providing the corresponding substitution products in high yields (13 examples, 62–98%). Moreover, other nucleophiles (allyltrimethylsilane, trimethylsilyl cyanide, 2,2‐dimethyl‐3‐(trimethylsilyloxy)butane, p‐toluenesulfonamide, and acetylacetone) reacted with a representative chiral electrophile in a high yielding and diastereoselective fashion.
Mass‐Spectrometric and Kinetic Studies on the Mechanism and Degradation Pathways of Titanium Salalen Catalysts for Asymmetric Epoxidation with Aqueous Hydrogen Peroxide
Authors: Berkessel Albrecht , Brandenburg Marc , Schäfer Mathias 
Published: April 2008

AbstractThe composition and degradation of a highly active and enantioselective titanium salalen in situ catalyst for the asymmetric epoxidation of olefins with aqueous hydrogen peroxide was investigated. Kinetic data and ESI‐MS studies point to a mononuclear titanium salalen as the catalytically active species. By means of ESI‐MS and selective monodeuteration of the salalen ligand, the oxidative degradation was studied. Upon exposure to aqueous hydrogen peroxide, the amine functionality of the salalen ligand is converted to the hydroxylamine, followed by loss of water and generation of the inactive titanium‐salen complex. This transformation limits the activity of the catalyst in the epoxidation of less electron‐rich olefins, such as 1‐octene.
Asymmetric Counterion Pair Catalysis: An Enantioselective Brønsted Acid‐Catalyzed Protonation
Authors: Rueping Magnus , Theissmann Thomas , Raja Sadiya , Bats Jan W. 
Published: April 2008

AbstractA new asymmetric Brønsted acid‐catalyzed cascade reaction involving a 1,4‐addition, enantioselective protonation and 1,2‐addition has been developed. This organocatalytic cascade not only provides for the first time 3‐ and 2,3‐substituted tetrahydroquinolines and octahydroacridines in good yields with high dia‐ and enantioselectivities under mild reaction conditions but additionally represents the first example of a chiral Brønsted acid‐catalyzed protonation reaction in an organocatalytic domino reaction. Furthermore, the new Brønsted acid‐catalyzed hydride‐proton‐hydride transfer cascade can be applied to prepare new molecular scaffolds with up to three new stereocenters in an efficient one‐pot reaction sequence.
Bioengineering functional copolymers. XI. Copper(II)‐poly(N‐vinyl‐2‐pyrrolidone‐co‐N‐isopropylacrylamide) macrocomplexes
Authors: Rzayev Zakir M. O. , Denizli B. Kirci , Denizli Haluk 
Published: April 2008

AbstractA series of poly(N‐vinyl‐2‐pyrrolidone‐co‐N‐isopropylacrylamide)s, poly(VP‐co‐NIPA) copolymers with different compositions were prepared by radical copolymerization of VP and NIPA in N,N′‐dimethylformamide at 65°C using 2,2′‐azobisisobutyronitrile as initiator. Cu(II)‐copolymer macrocomplexes were prepared by complexation of the copolymers with copper sulfate in aqueous solution at 40°C. The structure and composition of the copolymers, and the formation of coordinated Cu(II)‐complexes between amide VP units and Cu2+ ions, were studied by FTIR spectroscopy, DSC and TGA‐DTG in addition to electrical conductivity. Studies on the relationship between composition and thermal behavior showed that the values of Tg and Td of the copolymers and their coordinated macrocomplexes increased with increasing VP content. The copolymers predominantly show amorphous structure while their Cu(II)‐macrocomplexes show the presence of a crystalline phase. The conductive properties of the synthesized Cu(II)‐poly(VP‐co‐NIPA) complexes are also discussed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Varied Active‐Site Constraints in the Klenow Fragment of E. coli DNA Polymerase I and the Lesion‐Bypass Dbh DNA Polymerase
Authors: Cramer Janina , Rangam Gopinath , Marx Andreas , Restle Tobias 
Published: April 2008

AbstractWe report on comparative pre‐steady‐state kinetic analyses of exonuclease‐deficient Escherichia coli DNA polymerase I (Klenow fragment, KF−) and the archaeal Y‐family DinB homologue (Dbh) of Sulfolobus solfataricus. We used size‐augmented sugar‐modified thymidine‐5′‐triphosphate (TRTP) analogues to test the effects of steric constraints in the active sites of the polymerases. These nucleotides serve as models for study of DNA polymerases exhibiting both relatively high and low intrinsic selectivity. Substitution of a hydrogen atom at the 4′‐position in the nucleotide analogue by a methyl group reduces the maximum rate of nucleotide incorporation by about 40‐fold for KF− and about twelvefold for Dbh. Increasing the size to an ethyl group leads to a further twofold reduction in the rates of incorporation for both enzymes. Interestingly, the affinity of KF− for the modified nucleotides is only marginally affected, which would indicate no discrimination during the binding step. Dbh even has a higher affinity for the modified analogues than it does for the natural substrate. Misincorporation of either TTP or TMeTP opposite a G template causes a drastic decline in incorporation rates for both enzymes. At the same time, the binding affinities of KF− for these nucleotides drop by about 16‐ and fourfold, respectively, whereas Dbh shows only a twofold reduction. Available structural data for ternary complexes of relevant DNA polymerases indicate that both enzymes make close contacts with the sugar moiety of the dNTP. Thus, the varied proficiencies of the two enzymes in processing the size‐augmented probes indicate varied flexibility of the enzymes' active sites and support the notion of active site tightness being a criterion for DNA polymerase selectivity.
Controllable Synthesis of Nickel Hydroxide and Porous Nickel Oxide Nanostructures with Different Morphologies
Authors: Dong Lihong , Chu Ying , Sun Wendong 
Published: April 2008

Abstractα‐Ni(OH)2 nanobelts, nanowires, short nanowires, and β‐Ni(OH)2 nanoplates have been successfully prepared in high yields and purities by a convenient hydrothermal method under mild conditions from very simple systems composed only of NaOH, NiSO4, and water. It has been found that the ratio of NaOH to NiSO4 not only affects the morphology of the Ni(OH)2 nanostructures, but also determines whether the product is of the α‐ or β‐crystal phase. A notable finding is that porous NiO nanobelts were produced after exposure of the Ni(OH)2 products to an electron beam for several minutes during transmission electron microscopy (TEM) observations. Another unusual feature is that rectangular nanoplates with many gaps were obtained. Furthermore, porous NiO nanobelts, nanowires, and nanoplates could also be obtained by annealing the as‐prepared Ni(OH)2 products. A sequence of dissolution, recrystallization, and oriented attachment‐assisted self‐assembly of nanowires into nanobelts is proposed as a plausible mechanistic interpretation for the formation of the observed structures. The method presented here possesses several advantages, including high yields, high purities, low cost, and environmental benignity. It might feasibly be scaled‐up for industrial mass production.
Ionic Liquids of Bis(alkylethylenediamine)silver(I) Salts and the Formation of Silver(0) Nanoparticles from the Ionic Liquid System
Authors: Iida Masayasu , Baba Chihiro , Inoue Michiko , Yoshida Hibiki , Taguchi Eiji , Furusho Hirotoshi 
Published: April 2008

AbstractWe have prepared novel ionic liquids of bis(N‐2‐ethylhexylethylenediamine)silver(I) nitrate ([Ag(eth‐hex‐en)2]NO3 and bis(N‐hexylethylenediamine)silver(I) hexafluorophosphate ([Ag(hex‐en)2]PF6), which have transition points at −54 and −6 °C, respectively. Below these transition temperatures, both the silver complexes assume amorphous states, in which the extent of the vitrification is larger for the eth‐hex‐en complex than for the hex‐en complex. The diffusion coefficients of both the complex cations, measured between 30 (or 35) and 70 °C, are largely dependent on temperature; the dependence is particularly large in the case of the eth‐hex‐en complex cation below 40 °C. Small‐angle X‐ray scattering studies showed that the bilayer structure of the metal complex is formed in the liquid state for both the silver complexes. A direct observation of the yellowish [Ag(eth‐hex‐en)2]NO3 liquid by transmission electron microscopy (TEM) indicates the presence of nanostructures, as a microemulsion, of less than 5 nm. Such structures were not clearly observed in the [Ag(hex‐en)2]PF6 liquid. Although the [Ag(eth‐hex‐en)2]NO3 liquid is sparingly soluble in bulk water, it readily incorporates a small amount of water up to [water]/[metal complex]=7:1. Homogeneous and uniformly sized silver(0) nanoparticles in water were created by the reduction of the [Ag(eth‐hex‐en)2]NO3 liquid with aqueous NaBH4, whereas silver(0) nanoparticles were not formed from the [Ag(hex‐en)2]PF6 liquid in the same way.