Coherent Control of Trapped-Ion Qubits with Localized Electric Fields.

We present a new method for coherent control of trapped ion qubits in separate interaction regions of a multizone trap by simultaneously applying an electric field and a spin-dependent gradient. Both the phase and amplitude of the effective single-qubit rotation depend on the electric field, which can be localized to each zone. We demonstrate this interaction on a single ion using both laser-based and magnetic-field gradients in a surface-electrode ion trap, and measure the localization of the electric field.

Generation of a Maximally Entangled State Using Collective Optical Pumping.

We propose and implement a novel scheme for dissipatively pumping two qubits into a singlet Bell state. The method relies on a process of collective optical pumping to an excited level, to which all states apart from the singlet are coupled. We apply the method to deterministically entangle two trapped ^{40}Ca^{+} ions. Within 16 pumping cycles, an initially separable state is transformed into one with 83(1)% singlet fidelity, and states with initial fidelity of ⪆70% converge onto a fidelity of 93(1)%. We theoretically analyze the performance and error susceptibility of the scheme and find it to be insensitive to a large class of experimentally relevant noise sources.

C-ARM Guided Angiogram/Angioplasty for Selected Failed Arterio Venous Fistula. A Report of a Procedure at University Hospital of Nepal.

End Stage Renal Disease is a last stage of Chronic Kidney Disease which is characterized by Glomerular Filtration rate of less than 15 ml/min/1.73 m2 . Hemodialysis is the most commonly used modality for treatment of Chronic Kidney disease. Among the access for hemodialysis arteriovenous fistula is the most common modality. However most common problems of fistula are significant stenosis of more than 50% which is characterized by limb swelling, pigmentation, tortuous veins, and difficulty maintaining flow during dialysis from AV fistula. These can be managed either by minimal intervention or with surgical intervention. Very few hospitals in Nepal and other countries have an angiographic suite to perform minimal intervention include angiogram with angioplasty. So in this case we try to address the use of C-Arm to perform angiogram or fistulogram and even angioplasty for the management of significant stenosis or complications of arteriovenous fistula.

Deep amoA amplicon sequencing reveals community partitioning within ammonia-oxidizing bacteria in the environmentally dynamic estuary of the River Elbe.

The community composition of betaproteobacterial ammonia-oxidizing bacteria (ß-AOB) in the River Elbe Estuary was investigated by high throughput sequencing of ammonia monooxygenase subunit A gene (amoA) amplicons. In the course of the seasons surface sediment samples from seven sites along the longitudinal profile of the upper Estuary of the Elbe were investigated. We observed striking shifts of the ß-AOB community composition according to space and time. Members of the Nitrosomonas oligotropha-lineage and the genus Nitrosospira were found to be the dominant ß-AOB within the river transect, investigated. However, continuous shifts of balance between members of both lineages along the longitudinal profile were determined. A noticeable feature was a substantial increase of proportion of Nitrosospira-like sequences in autumn and of sequences affiliated with the Nitrosomonas marina-lineage at downstream sites in spring and summer. Slightly raised relative abundances of sequences affiliated with the Nitrosomonas europaea/Nitrosomonas mobilis-lineage and the Nitrosomonas communis-lineage were found at sampling sites located in the port of Hamburg. Comparisons between environmental parameters and AOB-lineage (ecotype) composition revealed promising clues that processes happening in the fluvial to marine transition zone of the Elbe estuary are reflected by shifts in the relative proportion of ammonia monooxygenase sequence abundance, and hence, we propose ß-AOB as appropriate indicators for environmental dynamics and the ecological condition of the Elbe Estuary.

Blood volume and pain perception during finger prick capillary blood sampling: are all safety lancets equal?

OBJECTIVES: This study aimed to assess various types of safety lancets in terms of blood volume and pain perception during capillary blood sampling, a routine finger-puncture procedure for obtaining a small amount of human blood for running various screening and diagnostic tests. METHODS: Data were collected from 100 adult healthy volunteers following finger-puncture procedure. Four different types of safety lancets were tested (Acti-Lance, Prolance, Medlance Plus, and MediSafe Solo). Each type has its own versions, giving 16 different safety lancets in total. RESULTS: A significant difference in the mean capillary blood volume was found between blade and needle equipped safety lancets. MediSafe Solo type lancet had no blade version, and hence its use was associated with the lowest mean collected capillary blood volume (42.4 µL). Acti-Lance and Medlance Plus type lancets had one blade version and the mean collected capillary blood volume was 82.2 and 99.0 µL, respectively. Prolance type lancet had two blade versions, and its use was associated with the highest mean capillary blood volume (118.3 µL). The level of pain intensity was evaluated as low by the majority of patients for all lancets. Medlance Plus was the least painful and Acti-Lance was the most painful type of safety lancet. On a 0-to-10 scale of pain, 75% of punctures were assessed by the participants at a level not exceeding 3 points. CONCLUSIONS: This study suggests that although all investigated safety lancets achieve adequate performance regarding the necessary capillary blood volume to run a diagnostic of test, lancets equipped with blades differ significantly from those equipped with needles in terms of the mean obtained capillary blood volume. Further, although all devices produced relatively low levels of pain, the amount of pain caused by blade versions of safety lancets has been found to be higher than that of needle versions. CLINICALTRIALS.GOV ID: NCT04001348. (https://clinicaltrials.gov/ct2/show/NCT04001348?term=NCT04001348&draw=2&rank=1).

Tricuspid valve leaflet strains in the beating ovine heart.

The tricuspid leaflets coapt during systole to facilitate proper valve function and, thus, ensure efficient transport of deoxygenated blood to the lungs. Between their open state and closed state, the leaflets undergo large deformations. Quantification of these deformations is important for our basic scientific understanding of tricuspid valve function and for diagnostic or prognostic purposes. To date, tricuspid valve leaflet strains have never been directly quantified in vivo. To fill this gap in our knowledge, we implanted four sonomicrometry crystals per tricuspid leaflet and six crystals along the tricuspid annulus in a total of five sheep. In the beating ovine hearts, we recorded crystal coordinates alongside hemodynamic data. Once recorded, we used a finite strain kinematic framework to compute the temporal evolutions of area strain, radial strain, and circumferential strain for each leaflet. We found that leaflet strains were larger in the anterior leaflet than the posterior and septal leaflets. Additionally, we found that radial strains were larger than circumferential strains. Area strains were as large as 97% in the anterior leaflet, 31% in the posterior leaflet, and 31% in the septal leaflet. These data suggest that tricuspid valve leaflet strains are significantly larger than those in the mitral valve. Should our findings be confirmed they could suggest either that the mechanobiological equilibrium of tricuspid valve resident cells is different than that of mitral valve resident cells or that the mechanotransductive apparatus between the two varies. Either phenomenon may have important implications for the development of tricuspid valve-specific surgical techniques and medical devices.

Randomized clinical trial comparing liver resection with and without perioperative assessment of liver function.

BACKGROUND: Liver function tests may help to predict outcomes after liver surgery. The aim of this study was to evaluate the clinical impact on postoperative outcome and patient management of perioperative liver function testing using the LiMAx® test. METHODS: A multicentre RCT was conducted in six academic liver centres. Patients with intrahepatic tumours scheduled for open liver resection of at least one segment were eligible. Patients were randomized to undergo additional perioperative liver function tests (LiMAx® group) or standard care (control group). Patients in the intervention arm received two perioperative LiMAx® tests, one before the operation for surgical planning and another after surgery for postoperative management. The primary endpoint was the proportion of patients transferred directly to a general ward. Secondary endpoints were severe complications, length of hospital stay (LOS) and length of intermediate care/ICU (LOI) stay. RESULTS: Some 148 patients were randomized. Thirty-six of 58 patients (62 per cent) in the LiMAx® group were transferred directly to a general ward, compared with one of 60 (2 per cent) in the control group (P < 0·001). The rate of severe complications was significantly lower in the LiMAx® group (14 per cent versus 28 per cent in the control group; P = 0·022). LOS and LOI were significantly shorter in the LiMAx® group (LOS: 10·6 versus 13·3 days respectively, P = 0·012; LOI: 0·8 versus 3·0 days, P < 0·001). CONCLUSION: Perioperative use of the LiMAx® test improves postoperative management and reduces the incidence of severe complications after liver surgery. Registration number: NCT01785082 ( https://clinicaltrials.gov).

Sustained State-Independent Quantum Contextual Correlations from a Single Ion.

We use a single trapped-ion qutrit to demonstrate the quantum-state-independent violation of noncontextuality inequalities using a sequence of randomly chosen quantum nondemolition projective measurements. We concatenate 53×10^{6} sequential measurements of 13 observables, and unambiguously violate an optimal noncontextual bound. We use the same data set to characterize imperfections including signaling and repeatability of the measurements. The experimental sequence was generated in real time with a quantum random number generator integrated into our control system to select the subsequent observable with a latency below 50 µs, which can be used to constrain contextual hidden-variable models that might describe our results. The state-recycling experimental procedure is resilient to noise and independent of the qutrit state, substantiating the fact that the contextual nature of quantum physics is connected to measurements and not necessarily to designated states. The use of extended sequences of quantum nondemolition measurements finds applications in the fields of sensing and quantum information.

Exogenous mineralization of hard tissues using photo-absorptive minerals and femto-second lasers; the case of dental enamel.

A radical new methodology for the exogenous mineralization of hard tissues is demonstrated in the context of laser-biomaterials interaction. The proposed approach is based on the use of femtosecond pulsed lasers (fs) and Fe3+-doped calcium phosphate minerals (specifically in this work fluorapatite powder containing Fe2O3 nanoparticles (NP)). A layer of the synthetic powder is applied to the surface of eroded bovine enamel and is irradiated with a fs laser (1040 nm wavelength, 1 GHz repetition rate, 150 fs pulse duration and 0.4 W average power). The Fe2O3 NPs absorb the light and may act as thermal antennae, dissipating energy to the vicinal mineral phase. Such a photothermal process triggers the sintering and densification of the surrounding calcium phosphate crystals thereby forming a new, dense layer of typically ∼20 µm in thickness, which is bonded to the underlying surface of the natural enamel. The dispersed iron oxide NPs, ensure the localization of temperature excursion, minimizing collateral thermal damage to the surrounding natural tissue during laser irradiation. Simulated brushing trials (pH cycle and mechanical force) on the synthetic layer show that the sintered material is more acid resistant than the natural mineral of enamel. Furthermore, nano-indentation confirms that the hardness and Young's modulus of the new layers are significantly more closely matched to enamel than current restorative materials used in clinical dentistry. Although the results presented herein are exemplified in the context of bovine enamel restoration, the methodology may be more widely applicable to human enamel and other hard-tissue regenerative engineering. STATEMENT OF SIGNIFICANCE: In this work we provide a new methodology for the mineralisation of dental hard tissues using femtosecond lasers and iron doped biomaterials. In particular, we demonstrate selective laser sintering of an iron doped fluorapatite on the surface of eroded enamel under low average power and mid-IR wavelength and the formation of a new layer to substitute the removed material. The new layer is evaluated through simulated brushing trials and nano-indentation. From the results we can conclude that is more acid resistant than natural enamel while, its mechanical properties are superior to that of current restorative materials. To the best of our knowledge this is the first time that someone demonstrated, laser sintering and bonding of calcium phosphate biomaterials on hard tissues. Although we here we discuss the case of dental enamel, similar approach can be adopted for other hard tissues, leading to new strategies for the fixation of bone/tooth defects.

The effect on dental enamel of the frequency of consumption of fluoridated milk with a cariogenic challenge in situ.

OBJECTIVES: To evaluate the effect on enamel of varying the frequency of consumption of 1.0 mg F in milk once per day, twice per day or once every other day under cariogenic challenge in situ. MATERIALS AND METHODS: In a controlled, randomised, cross-over, single-blind study, 25 subjects wore an intra-oral lower removable appliance with enamel slabs for 21 days during each study arm. Subjects used F-free toothpaste, the cariogenic challenge comprising of five 2 min dippings per day in a 12% sucrose solution. Subjects dipped the appliances in 50 ml of 5.0 ppm fluoridated milk for five minutes during the test period once per day, twice per day, and once every other day and drank 200 ml of the same milk, once per day, twice per day (100 ml each time), or once every other day (200 ml) immediately on re-inserting their appliance in order to replicate topical and systemic effects. Slabs were analysed with surface microhardness (SMH) for protection against further demineralisation and transverse microradiography (TMR) to assess changes in mineralisation. RESULTS: Using SMH, 200 ml of 5.0 ppm F milk once per day was significantly better than 100 ml of 5.0 ppm F twice/day (p < 0.05) and 200 ml once every other day, but not significantly. Using TMR there was a statistically significant difference in mineral loss of enamel between baseline and treatment for all groups, but not between groups. CONCLUSIONS: Drinking 200 ml of 5.0 ppm milk once per day every day protected enamel against further demineralisation whereas all three frequencies were effective in promoting remineralisation.

Echocardiographic imaging options in ovine research subjects.

OBJECTIVES: To determine the feasibility of acquiring quality transesophageal (TEE), epicardial (EE), and intracardiac (ICE) echocardiographic images in ovine subjects and to discuss the merits of each technique with a focus on ICE image acquisition. ANIMALS: Eleven male castrated Dorset adult sheep. METHODS: Transesophageal echocardiography was performed under general anesthesia. Epicardial echocardiography was performed as part of an open chest (thoracotomy or sternotomy) experiment. Subjects were recovered with permanent jugular vein indwelling catheter and ICE from this approach was described. Feasibility of each technique was qualitatively assessed based on subjective image quality from three images for each image plane in each sheep. RESULTS: Transesophageal echocardiography was technically challenging and did not provide adequate image quality for consistent interpretation. Epicardial echocardiography and ICE had more favorable results with ICE demonstrating unique benefits for post-operative serial monitoring. CONCLUSIONS: Epicardial echocardiography and ICE were effective imaging techniques. Epicardial echocardiography required the least specialized training but was considered to have limited feasibility due to its requirement for an open chest procedure. Even with the necessity for permanent indwelling jugular cannulation, ICE was the least invasive of the three imaging techniques and potentially the most practical approach for chronic studies by minimizing post-operative stress. Transesophageal echocardiography was not a feasible technique in this study.

Comparison of the newer preventive therapies on remineralisation of enamel in vitro.

OBJECTIVES: To investigate in vitro the effect of MI Paste, MI Paste Plus and 2800ppm fluoride (F) toothpaste (TP) on the remineralisation of enamel subsurface lesions and to compare these to the effect of 1450ppm and 0ppm F toothpastes. METHODS: Enamel subsurface lesions were created in bovine enamel slabs (n=120) which were assigned randomly to five groups; (1) 0ppm F TP, (2) 1450ppm F TP, (3) 2800ppm F TP, (4) 1450ppm F TP+MI Paste (Tooth Mousse-TM,10% w/v CPP-ACP) and (5) 1450ppm F TP+MI Paste Plus (Tooth Mousse Plus,10% w/v CPP-ACP, 900ppm F as 0.2% w/w sodium fluoride). The enamel slabs were subjected to a pH cycling regimen for 21days. Quantitative Light-induced Fluorescence (QLF) images were taken and analysed. Data analysis was carried out using one way ANOVA. RESULTS: In all groups, both ΔF (percentage fluorescence loss) and ΔQ (ΔF times the area) values improved significantly within the same group after the treatment. In addition, the mean difference in ΔF of the non-fluoride control group was significantly lower than all other groups but not for the 2800ppm F- group. Whereas the mean difference in ΔQ of the non-fluoride control of group was significantly lower when compared with all other groups (p<0.05). CONCLUSIONS: Both MI Paste and MI Paste Plus when used in conjunction with 1450ppm F did not show a significant increase in efficacy for the remineralisation of bovine enamel subsurface lesions in the model used in this study. CLINICAL SIGNIFICANCE: Newer preventive agents such as MI paste and MI paste plus are advocated as promoting remineralisation when used in addition to routine oral care. This in vitro study shows that they may have a limited value in promoting remineralisation over and above that of 1450ppm F toothpaste used twice a day.

ß-pyrophosphate: A potential biomaterial for dental applications.

Tooth hypersensitivity is a growing problem affecting both the young and ageing population worldwide. Since an effective and permanent solution is not yet available, we propose a new methodology for the restoration of dental enamel using femtosecond lasers and novel calcium phosphate biomaterials. During this procedure the irradiated mineral transforms into a densified layer of acid resistant iron doped ß-pyrophosphate, bonded with the surface of eroded enamel. Our aim therefore is to evaluate this densified mineral as a potential replacement material for dental hard tissue. To this end, we have tested the hardness of ß-pyrophosphate pellets (sintered at 1000°C) and its mineral precursor (brushite), the wear rate during simulated tooth-brushing trials and the cytocompatibility of these minerals in powder form. It was found that the hardness of the ß-pyrophosphate pellets is comparable with that of dental enamel and significantly higher than dentine while, the brushing trials prove that the wear rate of ß-pyrophosphate is much slower than that of natural enamel. Finally, cytotoxicity and genotoxicity tests suggest that iron doped ß-pyrophosphate is cytocompatible and therefore could be used in dental applications. Taken together and with the previously reported results on laser irradiation of these materials we conclude that iron doped ß-pyrophosphate may be a promising material for restoring acid eroded and worn enamel.

System Interdependency Modeling in the Design of Prognostic and Health Management Systems in Smart Manufacturing.

The fields of risk analysis and prognostics and health management (PHM) have developed in a largely independent fashion. However, both fields share a common core goal. They aspire to manage future adverse consequences associated with prospective dysfunctions of the systems under consideration due to internal or external forces. This paper describes how two prominent risk analysis theories and methodologies - Hierarchical Holographic Modeling (HHM) and Risk Filtering, Ranking, and Management (RFRM) - can be adapted to support the design of PHM systems in the context of smart manufacturing processes. Specifically, the proposed methodologies will be used to identify targets - components, subsystems, or systems - that would most benefit from a PHM system in regards to achieving the following objectives: minimizing cost, minimizing production/maintenance time, maximizing system remaining usable life (RUL), maximizing product quality, and maximizing product output. HHM is a comprehensive modeling theory and methodology that is grounded on the premise that no system can be modeled effectively from a single perspective. It can also be used as an inductive method for scenario structuring to identify emergent forced changes (EFCs) in a system. EFCs connote trends in external or internal sources of risk to a system that may adversely affect specific states of the system. An important aspect of proactive risk management includes bolstering the resilience of the system for specific EFCs by appropriately controlling the states. Risk scenarios for specific EFCs can be the basis for the design of prognostic and diagnostic systems that provide real-time predictions and recognition of scenario changes. The HHM methodology includes visual modeling techniques that can enhance stakeholders' understanding of shared states, resources, objectives and constraints among the interdependent and interconnected subsystems of smart manufacturing systems. In risk analysis, HHM is often paired with Risk Filtering, Ranking, and Management (RFRM). The RFRM process provides the users, (e.g., technology developers, original equipment manufacturers (OEMs), technology integrators, manufacturers), with the most critical risks to the objectives, which can be used to identify the most critical components and subsystems that would most benefit from a PHM system. A case study is presented in which HHM and RFRM are adapted for PHM in the context of an active manufacturing facility located in the United States. The methodologies help to identify the critical risks to the manufacturing process, and the major components and subsystems that would most benefit from a developed PHM system.

Perivascular tissue mediated relaxation - a novel player in human vascular tone regulation.

Perivascular tissue (PVT) modulates vascular tone, releasing adventitia/adipocyte derived relaxing factor (ADRF). Its physiological role remains unclear. We studied isolated internal thoracic artery (ITA) segments obtained from 132 patients subjected to coronary artery bypass grafting. The vessels were skeletonized in vitro and the ITA rings and PVT were incubated in separate isolated organ baths. Skeletonized ITA segments were first precontracted with 10(-5.5)mol/L 5-hydroxytryptamine hydrochloride. The PVT was next transferred to the ITA tissue bath. This resulted in relaxation of ITA, presumably related to ADRF release from PVT which was floating freely in the tissue bath. The in-vitro relaxation responses were then correlated to patients' characteristics - including demographics, clinical and laboratory data, as well as therapy. Perivascular tissue transfer resulted in 49.7 ± 26.2% relaxation of precontracted ITA segments. In multiple linear regression modelling, the relaxation of ITAto PVT was negatively related to patient age (ß = -0.67; 95% CI -1.17 - -0.17; P = 0.009), symptoms of CCS class 4 angina (ß = -20.11; 95%CI -32.25 - -7.97; P = 0.001), and positively to body mass (ß = 0.37; 95%CI 0.08 - 0.67; P = 0.01) and lack of heart failure symptoms (NYHA class 1) (ß = 9.06; 95%CI 0.33 - 17.79; P = 0.04). The relaxation response to PVT was not related to patients' sex, diabetes, hypertension, lipid profile or therapy in both univariate and multivariate analysis. PVT might play an important role in regulating vascular tone in humans as exemplified by its changing physiological function with age and in atherosclerosis.

Mechanisms of vasodilatatory effect of perivascular tissue of human internal thoracic artery.

It has beed showed that perivascular adipose tissue (PVAT) of human internal thoracic artery (ITA) releases adventitia/adipocyte-derived relaxing factor (ADRF). The precise mechanism of vasodilatatory effect of ADRF is still unknown. It was suggested that various potassium channels may be involved in the action of ADRF. The aim of this study was to assess the involvment of potassium channels in the vasorelaxing properties of ADRF in human internal thoracic artery. Human ITA rings were studied in vitro. First the ability of perivascular tissue of human ITA to release ADRF to the bath was checked. In subsequent experiments two fragments of skeletonised ITA were used to assess the involvement of various potassium channels in vasorelaxing action of PVAT. Segment of ITA, precontracted with serotonin (10(-5.5)M), was relaxed by adding PVAT to tissue bath, first without and then in the presence of appropriate potassium channel blocker. Second segment served as a control (no addition of PVAT). The magnitude of relaxation was measured and compared between preparations. This protocol was used to analyze the influence of iberiotoxin (100 nM), apamin (1 uM), 4-aminopyridine (1 mM, 5 mM), BaCl2 (100 uM) and glibenclamide (10 uM). The addition of PVAT to precontracted skeletonized ITA caused significant vasorelaxation (54.6±8.03 mN versus 33.7±6.58 mN p=0.03). Similar effect was seen when 5 ml of aliquot from separate incubation of PVAT was added (36.3±5.45 mN versus 20.7±3.02 mN; p<0.001). PVAT dependent relaxation was blocked in the presence of Ca⁺² dependent potassium channel blocker iberiotoxin (47.4±16.67 mN versus 43.3±14.54 mN; p=0.36) and 4-aminopyridine (5 mM) (59.3±3.54 mN versus 51.6±4.77 mN; p=0.12). We conclude that perivascular adipose tissue of human ITA releases relaxing factor that seems to act with the involvement of Ca⁺² dependent potassium channels.

The effect of varying concentrations of fluoridated milk on enamel remineralisation in vitro.

The aim of this in vitro single blind study was to investigate the dose response of fluoride in milk on enamel demineralisation and remineralisation under pH cycling using transverse microradiography (TMR). Enamel slabs (n = 11) with caries-like lesions were exposed to milk containing 6 different fluoride concentrations (0, 0.25, 0.5, 1.0, 5.0 and 10.0 ppm F). On each of the 14 days of the cycling period the lesions were exposed to five 2-minute periods of cariogenic challenge (1.5 mM CaCl2, 0.9 mM KH2PO4 and 50 mM acetic acid at pH 5.0) and two 5-min periods in milk plus 10 min in a milk/saliva (1:3) slurry. The slabs were stored at 37°C in artificial saliva throughout the cycling period and demineralisation and remineralisation was assessed by TMR using dedicated image software. Remineralisation (ΔZ) was observed in all fluoride groups in contrast to demineralisation in the non-fluoride control. Remineralisation was significant (p < 0.05) for all concentrations above 1.0 ppm F. The results showed that fluoride concentration in milk exhibited a clear dose dependency and that the presence of fluoride even at low concentrations promoted remineralisation in this pH-cycling model.

The effect on dental enamel of varying concentrations of fluoridated milk with a cariogenic challenge in situ.

OBJECTIVES: This study investigated the effect of two concentrations of fluoride in milk, 2.5 and 5.0 ppm, on the prevention of demineralisation with a cariogenic challenge compared with milk with 0 ppm F. METHODS: In a controlled, randomised, cross-over, double-blind in situ study, 23 subjects wore a lower removable appliance with 2 enamel slabs for 21 days during each study arm. Subjects used F-free toothpaste and the cariogenic challenge comprised of five 2 min dippings per day in 12% sucrose. The slabs were dipped in 50 ml of milk with 0 ppm, 2.5 ppm or 5.0 ppm F twice daily for 5 min. Subjects drank 100ml twice per day of the same milk. Slabs were analysed with Knoop microhardness to assess changes in mineralisation. RESULTS: Results showed that enamel was softened in all groups but the extent of enamel softness was reduced with an increasing concentration of F in milk, being highly significant for both F groups compared to the control (p<0.0001). 5.0 ppm F group showed a trend towards less softening compared to the 2.5 ppm F but was not statistically significant. CONCLUSIONS: In our in situ model, 2.5 and 5.0 ppm F in milk significantly protected enamel from demineralisation.

Pressure-induced phase transition in LiLuF4:Pr3+ investigated by an optical technique.

The luminescence and luminescence kinetics of LiLuF(4) doped with 1.5 at.% of Pr(3+) obtained at high hydrostatic pressure changing from ambient to 220 kbar applied in a diamond anvil cell are presented. It has been shown that pressure causes shift of the emission lines toward the red with rates of the order of single cm(-1) kbar(-1). The pressure-induced phase transition from tetragonal to fergusonite structure for pressure above 100 kbar was observed. The crystal field calculations performed showed that this phase transition reduces the point symmetry of the Pr(3+) site from the S(4) to the C(2) point group.