Citrate Effects on Amorphous Calcium Carbonate (ACC) Structure,Stability, and Crystallization

Understanding the role of citrate in the crystallization kinetics of amorphous calcium carbonate (ACC) is essential to explain the formation mechanisms, stabilities, surface properties, and morphologies of CaCO₃ biominerals. It also contributes to deeper insight into fluid–mineral interactions, both in nature and for industrial processes. In this study, ACC formation and its crystallization are monitored in real time as a function of citrate (CIT) concentration in solution. Additionally, synchrotron radiation pair distribution function analyses combined with solid‐state, spectroscopic, and microscopic techniques are used to determine the effect of CIT on ACC structure, composition, and size. Results show an increase in ACC lifetime coupled with an increase in CIT uptake by ACC and slight changes in ACC atomic structure with an increase in CIT concentration. ACC does not form at concentrations ≥ 75% CIT/Ca and vaterite is absent in all cases where CIT is present. These findings can be explained by CIT binding with Ca ions, thereby forming Ca–CIT complexes in solution and decreasing ACC and calcite saturation levels. The formation of CIT‐bearing ACC with calcitic structure and the absence of vaterite formation suggest that these solution complexes form a calcite‐type atomic arrangement while CIT probably also acts as a growth inhibitor.     

Potential Ecological Roles of Artemisinin Produced by Artemisia annua L.

Artemisia annua L. (annual wormwood, Asteraceae) and its secondary metabolite artemisinin, a unique sesquiterpene lactone with an endoperoxide bridge, has gained much attention due to its antimalarial properties. Artemisinin has a complex structure that requires a significant amount of energy for the plant to synthesize. So, what are the benefits to A. annua of producing this unique compound, and what is the ecological role of artemisinin? This review addresses these questions, discussing evidence of the potential utility of artemisinin in protecting the plant from insects and other herbivores, as well as pathogens and competing plant species. Abiotic factors affecting the artemisinin production, as well as mechanisms of artemisinin release to the surroundings also are discussed, and new data are provided on the toxicity of artemisinin towards soil and aquatic organisms. The antifungal and antibacterial effects reported are not very pronounced. Several studies have reported that extracts of A. annua have insecticidal effects, though few studies have proven that artemisinin could be the single compound responsible for the observed effects. However, the pathogen(s) or insect(s) that may have provided the selection pressure for the evolution of artemisinin synthesis may not have been represented in the research thus far conducted. The relatively high level of phytotoxicity of artemisinin in soil indicates that plant/plant allelopathy could be a beneficial function of artemisinin to the producing plant. The release routes of artemisinin (movement from roots and wash off from leaf surfaces) from A. annua to the soil support the rationale for allelopathy.     

Physiological features of periodontal regeneration and approaches for periodontal tissue engineering utilizing periodontal ligament cells

Experimental studies have shown that the potential of periodontal regeneration seems to be limited by the regenerative capacity of the cells involved. The regeneration of damaged periodontal tissues is mediated by various periodontal cells and is regulated by a vast array of extracellular matrix informational molecules that induce both selective and nonselective responses in different cell lineages and their precursors. In this paper, we first review periodontal ligament tissue and its different cell subpopulations including fibroblasts and paravascular stem cells, and their functions during the development and homeostasis of periodontal tissues. Because conventional periodontal regeneration methods remain insufficient to obtain a complete and reliable periodontal regeneration, the concept of periodontal tissue engineering has been based on the generation of the conditions necessary to improve the healing of periodontal tissues. Additionally, the potential of periodontal ligament cells for use in periodontal tissue engineering to overcome the limitations of conventional periodontal regenerative therapies is discussed, followed by an update of the recent progress and future directions of research utilizing periodontal ligament cells for predictable periodontal regeneration.     

Behavior of Listeria monocytogenes type1 355/98 (85) in meat emulsions as affected by temperature,pH, water activity,fat and microbial preservatives

The aim of this work was to analyze the effect of temperature (10–30 °C), fat content (20–50%), sodium chloride (2.5–5.0%) and preservative concentrations: sodium nitrite (0–150 ppm), lactic acid (50–500 mM) and nisin (0–100 IU/g (international units per gram)) on the growth of Listeria monocytogenes in a meat emulsion system.Individual and simultaneous effects of the parameters were tested and the results were mathematical modeled; inhibition indexes were calculated in each case. The addition of 7.5% NaCI inhibited the growth of L. monocytogenes at 20 and 30 °C, however, at 10 °C, microbial counts reached approximately 10⁶ CFU/g. The addition of 50 mM of lactic acid to obtain a pH ≤ 5 inhibited the growth of L. monocytogenes. The combinations of lactic acid with sodium nitrite or with nisin showed an enhancement of the inhibitory effect. However, considering the low toxicity of nisin, the combination of lactic acid (50 mM) and nisin (20 IU/g) would be more acceptable in the prevention of the growth of Listeria monocytogenes.     

Real-space imaging of inelastic Friedel-like surface oscillations emerging from molecular adsorbates

We report real space imaging measurements of inelastic Friedel oscillations. The inelastic electron tunneling spectroscopy, using scanning tunneling microscopy, around dimers of dichlorobenze adsorbates on Au(111) surface display clear spatial modulations that we attribute to inelastic scattering at the molecular sites caused by molecular vibrations. Due to local interactions between the adsorbate and the surface states, the molecular vibrations generate a redistribution of the charge density at energies in a narrow range around the inelastic mode. Our experimental findings are supported by theoretical arguments.     

Treatment of vitamin D deficiency/insufficiency with ergocalciferol is associated with reduced vascular access dysfunction in chronic hemodialysis patients

Vitamin D deficiency or insufficiency is highly prevalent among patients with chronic kidney disease (CKD). This study aims to determine the relationship between vitamin D and frequency of vascular access dysfunction (VAD) in hemodialysis (HD) patients. We reviewed medical records of all HD patients who had serum 25‐hydroxyvitamin D (25OHD) levels at 4 outpatient dialysis facilities between January 2011 and January 2012. Patients were included if they were ≥18 years of age, had been on maintenance dialysis for ≥3 months, and had native arteriovenous fistula or synthetic polytetrafluoroethylene grafts for dialysis access. Patients with catheters were excluded. 25‐Hydroxyvitamin D levels <30 ng/mL were documented in 183 patients (86%). Median and interquartile range [Q1, Q3] of 25OHD level was 16 [11, 25] ng/mL. Among 213 dialysis patients, 102 had VAD. Median 25OHD level was significantly lower in patients who had VAD than in those without VAD (14.5 [10, 22] vs. 19 [12, 27.5] ng/mL; P = 0.003). There was significant association between VAD and the lowest quartile relative to the highest quartile of 25OHD level. A 25OHD level <12 ng/mL was associated with more than doubling of risk for VAD (OR 2.56; 95% CI [1.05–6.23], P < 0.05). Of 213 patients, 140 were treated with ergocalciferol and 73 were not treated. Treatment was associated with significant reduction in VAD (OR = 0.36; 95% CI [0.19–0.68], P = 0.002). Vitamin D deficiency or insufficiency is an independent risk factor for VAD in HD patients; its treatment with ergocalciferol is associated with decreased VAD.     

Enrichment of Banana with <Emphasis Type="Italic">Lactobacillus rhamnosus</Emphasis> Using Double Emulsion and Osmotic Dehydration

The aim of this study was to use the process of osmotic dehydration to enrich banana slices with Lactobacillus rhamnosus encapsulated in a double emulsion. The effect of a pulsed vacuum and the concentration of the osmotic solution on the impregnation of the microorganism and on mass transfer during osmotic dehydration of the fruit were assessed. The kinetics of the water loss (WL), solid gain (SG) and water activity (a_w) were obtained using an aqueous solution with 40, 50 and 60% sucrose with emulsion and a vacuum pulse of 50 mbar for 10 and 20 min at the beginning of the osmotic process. The high concentrations of sucrose in the osmotic solution, combined with the application of a pulsed vacuum, produced an increase in the rates of WL and SG of the osmodehydrated banana, as well as a reduction of its a_w. L. rhamnosus survived at levels above 10⁷ CFU/g in the hypertonic solution and in the osmodehydrated bananas. Scanning electron microscopy (SEM) showed that the encapsulated probiotic adheres to the banana’s surface, which demonstrates that double emulsions can be used to impregnate probiotics in vegetal tissues.