Emission properties of hydrothermal Yb(3+), Er(3+) and Yb(3+), Tm(3+)-codoped Lu2O3 nanorods: upconversion, cathodoluminescence and assessment of waveguide behavior

Yb(3+) and Ln(3+) (Ln(3+) = Er(3+) or Tm(3+)) codoped Lu(2)O(3) nanorods with cubic Ia3 symmetry have been prepared by low temperature hydrothermal procedures, and their luminescence properties and waveguide behavior analyzed by means of scanning near-field optical microscopy (SNOM). Room temperature upconversion (UC) under excitation at 980 nm and cathodoluminescence (CL) spectra were studied as a function of the Yb(+) concentration in the prepared nanorods. UC spectra revealed the strong development of Er(3+) (4)F(9/2) → (4)I(15/2) (red) and Tm(3+) (1)G(4) → (3)H(6) (blue) bands, which became the pre-eminent and even unique emissions for corresponding nanorods with the higher Yb(3+) concentration. Favored by the presence of large phonons in current nanorods, UC mechanisms that privilege the population of (4)F(9/2) and (1)G(4) emitting levels through phonon-assisted energy transfer and non-radiative relaxations account for these observed UC luminescence features. CL spectra show much more moderate development of the intensity ratio between the Er(3+) (4)F(9/2) → (4)I(15/2) (red) and (2)H(11/2), (4)S(3/2) → (4)I(15/2) (green) emissions with the increase in the Yb(3+) content, while for Yb(3+), Tm(3+)-codoped Lu(2)O(3) nanorods the dominant CL emission is Tm(3+) (1)D(2) → (3)F(4) (deep-blue). Uniform light emission along Yb(3+), Er(3+)-codoped Lu(2)O(3) rods has been observed by using SNOM photoluminescence images; however, the rods seem to be too thin for propagation of light.     

Regulation of acetic acid production by homo-and heterofermentative lactobacilli in whole-wheat sour-doughs

The efficiency of sour-dough as a possible preservative agent of microbial spoilage of bread depends on its acetic acid content. As a secondary metabolite of sugar fermentation by lactic acid bacteria, acetic acid may be promoted in the presence of O₂ or H⁺ acceptors. This paper studies the influence of O₂ and high fructose content products (pure sugar, invert sugar, fructose syrup) addition on acetic acid production by hetero- (Lactobacillus brevis 25a, B-21, L-62;L. sanfrancisco L-99) and homofermentative (L. plantarum B-39) lactobacilli in whole-wheat sour-doughs [280 and 250 dough yield (DY)]. The pH and total titratable acidity (TTA) of sour-doughs after 44 h fermentation varied with DY and strain. As expected, the addition of O₂ promoted greater increases in TTA with heterofermentative lactobacilli (15–42%) than withL. plantarum (15%). Fructose addition was only effective for heterofermentative strains, but the overall effects were smaller than those observed for oxygenation. The ability of lactobacilli to produce acetic acid in sour-doughs without treatment varied from 0.16 g/100 g flour at 44 h (B-39, 280, 350 DY) to 0.47–0.65% (L-62, 280, 350 DY). The production of acetic acid was positively promoted by all treatments. Oxygenation was again the most effective way of inducing acetic acid production; increases ranged from 54% (B-21) to 269% (L-99, 350 DY). The addition of H⁺ acceptors had variable effects. Pure fructose resulted, in general, in greater increases than invert sugar of fructose syrup. The main effects were detected forL. brevis 25a (280 DY) B-21 (350 DY) andL sanfrancisco L-99 (350 DY) with increases ranging from 92 to 123%. The highest levels of acetic acid (1.02–1.04%) corresponded to sour-doughs (44 h, 35° C shaking 150 rpm) started with L-62 (280, 350 DY) or L-99 (350 DY).

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Beeinflussung der Essigsäurebildung durch homo- und heterofermentative Laktobacillen in Weizenvollkornsauerteigen

Zusammenfassung Die Haltbarkeit von Sauerteig-Brot gegen mikrobiologische Verderbnis beruht auf seinem Säuregehalt. Als sekundäres Stoffwechselprodukt der Zuckergärung durch Milchsäurebakterien, kann die Essigsäure-Bildung von Sauerstoff- oder Wasserstoffacceptoren gefördert werden. Diese Veröffentlichung befaßt sich mit dem Einfluß von Sauerstoff und Produkten mit hohem Fructosegehalt (Rohrzucker, Invertzucker, Fructose-Sirup) auf die Essigsäure-Bildung durch hetero- (Lactobacillus brevis B-21, 25a, L-62;L. sanfrancisco L-99) und homofermentative (L. plantarum B-39) Laktobacillen in Weizenvollkornsauerteigen (TA 280 und 350). ph-Wert und Säuregrad von Sauerteigen nach 44-stündiger Gärung waren verschieden je nach TA und Stamm. Wie erwartet, verursachte die Zugabe von Sauerstoff eine größere Zunahme des Säuregrades mit heterofermentativen Laktobacillen (15–42%) als mitL. plantarum (15). Fructose-Zugabe war nur wirksam für die heterofermentativen Stämme, aber die allgemeinen Wirkungen waren kleiner als die bei der Behandlung mit Sauerstoff beobachteten. Die Fähigkeit von Laktobazillen, ohne Behandlung in Sauerteigen Essígsäure zu bilden, schwankte zwischen 0.16 g/100 g Mehl (B-39, 280, 350 TA) und 0.47–0.65% (L-62, 280, 350 TA). Die Bildung von Essigsäure wurde durch alle Behandlungen gefördert. Die Behandlung mit Sauerstoff war wieder die effizienteste zur Förderung der Essigsäurebildung; der Anstieg schwankte zwischen 54% (B-21) und 269% (L-99, 350 TA). Die Zugabe von Wasserstoffacceptoren hatte verschiedene Effekte. Reine Fructose ergab im allgemeinen größere Anstiege als Invertzucker oder Fructose Sirup. Die Haupteffekte wurden beiL. brevis 25a (280 TA), B-21 (350 TA) undL. sanfrancisco L-99 (350 TA) mit Anstiegen von 92% bis 123% nachgewiesen. Die mit L-62 (280, 350 TA) oder L-99 (350 TA) hergestellten Sauerteige (44 h, 35 °C, 150 rpm schütteln) ergaben die höchste Gehalte an Essigsäure (1.02–1.04%).

     

Absorption of sorbic and benzoic acids in the flesh of table olives

The distribution of sorbic and benzoic acids in the different phases of table olives was studied. To a large extent, these preservatives accumulated in the oil phase of fruits stored in acid conditions, as well as in juice and other tissue components. Thus, around 20–30% of the benzoic acid in olives was found in the juice phase, 30–50% in the oil phase and 30–40% in the rest of the olive flesh. Experiments carried out with black ripe olives revealed that an increase in pH of the medium gave rise to a decrease in the absorption phenomenon in whole olives and in the oil phase. As a consequence of this effect, benzoic acid could be leached from stored black ripe olives during the darkening process, although the calcium content of fruits greatly influenced the diffusion phenomenon. The results obtained in this study are important for future legal limitations of these preservatives in table olives and inhibition capacity of them in commercial table olives.     

Rich Phase Behavior in a Supramolecular Conducting Material Derived from an Organogelator

Organic conducting fiber‐like materials hold great promise for the development of nanowires that can act as connections in miniature electronic devices, as an alternative to inorganic nanometer scale structures. This article presents a conducting organic tetrathiafulvalene‐based supramolecular material which possesses a rich phase behavior with different packing of the molecules in the different forms, evidenced by electron spin resonance (ESR) spectroscopy. The distinct phases of conducting nanofibers can be easily fabricated through the temperature control of their preparation process from a xerogel by doping with iodine vapors. A total of four conducting phases have been identified conclusively using ESR spectroscopy as the key analytical tool. Three of the phases show a good long‐term stability and areas in which the I–V curves have ohmic behavior when studied by current sensing (conducting) AFM. They offer promise for applications where electrical nanometer scale connections are required.     

Thermal properties of doughs formulated with enzymes and starters

 Thermal properties (gelatinization, amylose-lipid complex dissociation and amylopectin retrogradation) of bread samples formulated with two different quality wheat flours, two enzymes (α-amylase/pentosanase, lipase and their mixture), and three microbial sourdough starters were studied with a differential scanning calorimeter. The carbohydrases modified gelatinization temperature and enthalpy, whilst the lipase modified the amylose-lipid complex dissociation. The enthalpy of amylopectin retrogradation was significantly influenced only by the storage of breads. Second-order interactive effects of enzymes with flour or starter were found for gelatinization and/or amylose-lipid complex dissociation parameters. Some interesting relationships were observed between thermal and textural properties of fresh and stored breads. Received: 22 September 1998 / Revised version: 28 October 1998     

Expression of the CD8alpha beta-heterodimer on CD8(+) T lymphocytes in peripheral blood lymphocytes of human immunodeficiency virus- and human immunodeficiency virus+ individuals

CD8(+) T lymphocytes play a pivotal role in controlling human immunodeficiency virus (HIV)-1 replication in vivo. We have performed four-color flow cytometric analysis of CD8(+) peripheral blood lymphocytes (PBL) from 21 HIV-1 seronegative and 103 seropositive individuals to explore the phenotypic heterogeneity of CD8beta-chain expression on CD8(+) T lymphocytes and to clarify how its expression on CD8(+) T lymphocytes may relate to acquired immunodeficiency syndrome (AIDS) clinical progression. We showed that the single monoclonal antibody (MoAb) 2ST8-5H7, directed against the CD8alpha beta-heterodimer, identifies CD8(+) T lymphocytes as effectively as the conventional combination of anti-CD3 and anti-CD8alpha antibodies. However, we detected a significantly lower mean fluorescence (MF) of anti-CD8alpha beta staining on PBL from HIV-1 seropositive donors as compared with seronegative donors. In fact, CD8(+) T lymphocytes from HIV-1-infected individuals with the lowest CD4 counts showed the lowest levels of CD8alpha beta MF. To explore further this change in CD8alpha beta expression, we assessed the expression of 14 different cell surface molecules on CD8alpha beta+ T lymphocytes of PBL from 11 HIV-1 seronegative and 22 HIV-1 seropositive individuals. The MF of anti-CD8alpha beta staining was significantly reduced on CD8(+) T lymphocyte subsets that showed immunophenotypic evidence of activation. The subset of lymphocytes expressing low levels of CD8alpha beta expressed higher levels of activation, adhesion, and cytotoxic-associated molecules and was predominantly CD45RO+ and CD28(-). Finally, we monitored the expression of the CD8alpha beta-heterodimer on PBL of eight HIV-1-infected individuals over a 16-week period after the initiation of highly active antiretroviral therapy (HAART), including zidovudine (ZDV), lamivudine (3TC), and indinavir (IDV), and found a significant increase in the expression of the CD8alpha beta-heterodimer. These results suggest that antibodies recognizing the CD8alpha beta-heterodimer are useful tools to specifically identify CD8(+) T lymphocytes. Moreover, the quantitative monitoring of CD8alpha beta expression allows the detection of discrete CD8(+) T lymphocyte subsets and may be useful for assessing the immune status of individuals infected with HIV-1.     

Competitive inhibitors of Helicobacter pylori type II dehydroquinase: synthesis, biological evaluation, and NMR studies

Several 3-heteroaryl analogs of the known dehydroquinase inhibitor (1R,4R,5R)-1,4,5-trihydroxy-2-cyclohexene-1-carboxylic acid (4) were synthesized and tested as inhibitors of Helicobacter pylori type II dehydroquinase, the third enzyme of the shikimic acid pathway. All of these compounds proved to be reversible competitive inhibitiors of this enzyme and proved to be, with the exception of nitrile 8 e, more potent than the parent inhibitor 4 (K(i)=370 microM). The 2-thienyl derivative 8 b was found to be the most potent inhibitor of the series and has a K(i) value of 540 nM, which is almost seven hundred times lower than that of the parent inhibitor. The 3-nitrothienyl derivative 8 d and 2-furanyl derivative 8 a also had a good affinity of 1 microM. The conformation of the potent competitive inhibitor 8 b, when bound in the active site of the H. pylori enzyme, was elucidated by 1D-selective inversion NOE, Saturation Transfer Difference (STD) and transferred NOESY NMR experiments. One of the conformations that exists in solution for the potent competitive inhibitor 2-thienyl derivative 8 b is selected when it is bound to the active site of the enzyme. In the bound conformation derivative 8 b has the sulfur atom of its thienyl group oriented towards the double bond of the cyclohexene moiety. The large STD effects observed for the aromatic protons of 8 b show that it is the thiophene side of the ligand that makes closest contact with enzyme protons. Docking studies using GOLD3.0.1 suggest that the conformation determined by NMR allows strong lipophilic interactions with the enzyme residues Pro9, Asn10, Ile11, Gly78 and Ala 79. Competitive STD experiments carried out with high-, medium- and low-affinity ligands 8 b, 5 d and 5 f show that they all bind in the same site of Helicobacter pylori dehydroquinase.     

Cooperative learning strategies to teach nutrition to geriatric nursing staff

The objective of this study was to test the hypothesis that cooperative learning strategies will help to increase nutrition knowledge of nurses and nursing assistants caring for the elderly in different institutional communities of the Basque Country, Spain. The target population was a sample of volunteers, 16 nurses and 28 nursing assistants. Training consisted of 12 nutrition education sessions using cooperative strategies conducted over a period of 3 consecutive weeks. The assessment instruments included two pretest and two posttest questionnaires with questions selected in multiple-choice format. The first questionnaire was about general knowledge of applied nutrition (0-88 point scale) and the second one on geriatric nutrition knowledge (0-18 point scale). Data were analyzed using SPSS vs. 11.0. The outcomes indicated a significant increase in general nutrition knowledge (difference between the pre- and post-test mean score: 14.5+/-10.1; P<0.001) and in geriatric nutrition knowledge for all participants (difference between the pre- and post-test mean score: 4.6+/-4.6; P<0.001). So the results indicated that cooperative learning strategies could improve the nutrition knowledge of nursing staff. Additionally, the results of this study provide direction to continuing nutrition education program planners regarding appropriate content and methodology for programs.     

Wettability and osteoblastic cell adhesion on ultrapolished commercially pure titanium surfaces: the role of the oxidation and pollution states

The oxidation state of the surfaces of titanium-based biomaterials strongly depends on their previous history. This factor affects the titanium wettability and it probably conditions the success of the implanted biomaterials. However, the separate role of the pollution and oxidation states of metallic titanium surfaces remains still controversial. To elucidate this, it is required to standardize the initial surface state of titanium in terms of roughness and surface chemistry, and then, to monitor its wettability after the corresponding treatment. In this work, we studied finely polished surfaces of commercially pure titanium (cpTi) which were subjected to cleaning surface treatments. X-Photoelectron spectroscopy was used to characterize the surface chemistry and the oxide film thickness. The contact angle hysteresis in underwater conditions was measured with the growing/shrinking captive bubble method, which allowed for mimicking the real conditions of implantable devices. The water wettability of smooth cpTi surfaces was stabilized with weak thermal oxidation (230?°C, 30?min). The osteoblastic cell response of the stabilized and non-stabilized cpTi surfaces was analyzed. Although the oxidation and pollution states were also stabilized and normalized, no correlation was observed between the stable response in wettability of titanium and its cell adhesion.     

Quality characteristics of different red pepper cultivars (<Emphasis Type="Italic">Capsicum annuum</Emphasis> L.) for hot paprika production

Twelve hybrids obtained by crossing of different Hungarian cultivars and the Spanish ‘Jaranda’, ‘Jariza’ and ‘Jeromín’ have been studied. The aim of this work was to select those peppers with high capsaicinoids content, and good agronomic and industrial characteristics, as ‘Jeromín’, the only local cultivar used for pungent (hot) paprika, has a low and irregular pungency depending on the year. The crop productive characteristics, ASTA colour, carotenoid pigment content and pungency of the paprika has been studied and elaborated following the traditional procedure of La Vera (Extremadura, Spain). The productive characteristics and pigment concentration of the crossings were, in general, similar to that of local cultivars, and all of them could be suitable for hot paprika production, because their capsaicinoid content was higher than that of ‘Jeromín’ (78 mg kg⁻¹ dwt of total capsaicinoids). The most pungent hybrids were Kibedicsipos × Jariza, Jeromín × Szegedi178 and Jaranda × Szegedi179, with a total capsaicinoid content of 1,240, 1,107, and 997 mg kg⁻¹ dwt, respectively. Their paprikas showed a carotenoid pigment content higher than that of ‘Jaranda’, which is considered as a high quality paprika.