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Intra-band transitions in colloidal quantum dots (QDs) are promising for opto-electronic applications in the mid-IR spectral region. However, such intra-band transitions are typically very broad and spectrally overlapping, making the study of individual excited states and their ultrafast dynamics very challenging. Here, we present the first full spectrum two-dimensional continuum infrared (2D CIR) spectroscopy study of intrinsically n-doped HgSe QDs, which exhibit mid-infrared intra-band transitions in their ground state. The obtained 2D CIR spectra reveal that underneath the broad absorption line shape of ∼500 cm−1, the transitions exhibit surprisingly narrow intrinsic linewidths with a homogeneous broadening of 175–250 cm−1. Furthermore, the 2D IR spectra are remarkably invariant, with no sign of spectral diffusion dynamics at waiting times up to 50 ps. Accordingly, we attribute the large static inhomogeneous broadening to the distribution of size and doping level of the QDs. In addition, the two higher-lying P-states of the QDs can be clearly identified in the 2D IR spectra along the diagonal with a cross-peak. However, there is no indication of cross-peak dynamics indicating that, despite the strong spin–orbit coupling in HgSe, transitions between the P-states must be longer than our maximum waiting time of 50 ps. This study illustrates a new frontier of 2D IR spectroscopy enabling the study of intra-band carrier dynamics in nanocrystalline materials across the entire mid-infrared spectrum. [ABSTRACT FROM AUTHOR]

Purpose: The intention of the study was to evaluate whether Sub-Saharan schoolteachers may play a key role in oral health promotion of primary schoolchildren, particularly in terms of prevention of HIV/AIDS-related oral health problems. Materials and Methods: The study examined the level of knowledge about oral disease and the prevention of HIV/ AIDS oral lesions amongst schoolteachers of Tanzania and Burkina Faso, identified their sources of information, and evaluated their ability for HIV/AIDS intervention. A multi-centre cross-sectional study was implemented in the two Sub-Saharan African countries. Participants comprised primary school teachers selected by stratified cluster sampling: 261 teachers from Tanzania and 313 teachers from Burkina Faso. All participants completed a structured questionnaire prepared for self-administration. The questions were designed from a standardised questionnaire developed by the World Health Organization. Results: Most teachers knew about the principal causes of the major oral diseases and the means of disease prevention. Nearly all teachers (95.6%) were aware of HIV/AIDS and they knew (92.3%) a virus was the direct cause of AIDS. Teachers were well informed of the general symptoms of HIV/AIDS, although oral symptoms were mentioned less often. In all, 17.6% of schoolteachers reported that children suffering from HIV/AIDS were found in their classes and 10.3% of teachers were conscious of students receiving anti-retroviral therapy (ART). Knowledge about the disease seemed to reflect mass media as a source, while teacher colleagues and health personnel played a somewhat lesser role in communication. In total, 83.2% emphasised that they should teach children about HIV/AIDS and the mouth. Schoolteachers from Tanzania (70.5%) were more often engaged in classroom-based oral health education than were the Burkinabe teachers (53.9%). Conclusion: The study confirms that schoolteachers may be a relevant source in the fight against HIV/AIDS among children. However, they would benefit from interaction with health personnel. [ABSTRACT FROM AUTHOR]

While the mid-infrared spectral region spans more than 3000 cm−1, ultrafast mid-IR spectroscopies are normally limited to the spectral bandwidth that can be generated in optical parametric amplifiers—typically a few hundred cm−1. As such, the spectral coverage in conventional two dimensional infrared (2D IR) spectroscopy captures only about 1% of the full potential 2D mid-IR spectrum. Here, we present 2D IR spectra using a continuum source as both the excitation and probe pulses, thus capturing close to the full 2D IR spectrum. While the continuum pulses span the entire mid-IR range, they are currently too weak to efficiently excite molecular vibrational modes but strong enough to induce electronic responses and excite phonons in semiconductors. We demonstrate the full spectrum 2D IR spectroscopy of the mid-IR bandgap semiconductor indium arsenide with a bandgap at 2855 cm−1. The measured response extends far below the bandgap and is due to field-induced band-shifting, causing probe absorption below the bandgap. While the band-shifting induces an instantaneous response that exists only during pulse overlap, the 2D IR spectra reveal additional off-diagonal features that decay on longer timescales. These longer-lived off-diagonal features result from coherent phonons excited via a Raman-like process at specific excitation frequencies. This study illustrates that the full spectrum 2D IR spectroscopy of electronic states in the mid-IR is possible with current continuum pulse technology and is effective in characterizing semiconductor properties. [ABSTRACT FROM AUTHOR]

Purpose: The first large-scale epidemiological survey on dental caries in Slovenia was conducted in 1987 and repeated in 1993, 1998, 2003, 2008, 2013 and 2017, using the same methodology. The aim of the study was to examine the trend of caries in 12-year-olds in Slovenia during a 30-year time period. The changes over time in caries experience were compared with disease trends observed in other European countries. Study Populations and Methods: The WHO National Oral Health Pathfinder Survey was applied in all seven surveys (1987-2017). The surveys were carried out in all nine geographical regions of Slovenia. For each subject, the caries experience and presence of sealants were recorded.Results: The mean DMFT of 12-year-olds decreased significantly from 5.1 in 1987 to 1.5 in 2017 (p < 0.0001). The percentage of persons with sealed teeth increased from 6% in 1987 to 94% in 2017, and the percentage of caries-free persons increased from 6% to 42%.Conclusion: The implementation of a nation-wide preventive programme was determined to significantly contribute to the effective control of caries and continuously improve the oral health of Slovenian children. In an international perspective, the Slovenian achievements in disease prevention in terms of caries prevalence reduction may be important for other countries of the region. [ABSTRACT FROM AUTHOR]

Purpose: Improved oral health of children is noted in most Western countries, but this coincides with a high burden of oral disease in several countries of Central and Eastern Europe. The purpose of the present study was to describe the current level of dental caries in Hungarian children aged 5, 6, and 12 years and to assess the long-term trends in caries over 30 years. In addition, the report aims to highlight the oral health habits of 12-year-old children in Hungary.Materials and Methods: A representative survey was undertaken in 2016-2017 according to the WHO Pathfinder methodology, which was also applied in previous national oral health surveys of 1985, 1991, 1996, 2001, and 2008. Children of 5-6 and 12 years were sampled systematically in all surveys over 30 years. Data were gathered through clinical examinations and a questionnaire used for 12-year-olds.Results: In 2016-2017, 42.6% of 5- to 6-year-olds were caries free, with the proportion lower in rural than urban settings. Approximately four primary teeth were affected by caries among children aged 5-6 years. Most of the disease burden consisted of untreated caries. Caries experience was higher for children living in rural areas. At age 12, about two permanent teeth suffered from caries, and the D-component of the caries index was high. The percentage of caries-free 6-year-olds grew from 9% in 1985 to 42.6% in 2016-2017. In 1985, 12-year-olds had on average 5 teeth affected by caries, and after 30 years, the level of caries declined to 2.3 DMFT in 2016-2017. The responses to the questionnaire showed that 11.9% of 12-year-olds visited the dentist because of oral pain or discomfort and 40.5% were dissatisfied by the appearance of their teeth. About 40% of children consumed soft drinks or sweets/candy, several times a day.Conclusions: Hungary has not yet achieved the WHO goals for children aged 5-6. While Hungary accomplished the WHO goal for oral health of 12-year-olds by the year 2000, it is seems unrealistic for the country to achieve the WHO goal for 12-year-olds by the year 2020. For better oral health of children, strong emphasis should be given to population-directed oral disease prevention, including the reduction of sugar consumption and implementing public health programmes for the effective use of fluoride. [ABSTRACT FROM AUTHOR]

Aqueous surfaces mediate many atmospheric, biological, and technological processes. At the interface, the bulk hydrogen-bonding network is terminated and the interfacial water molecules restructure according to the surface chemistry of the interface. Given the complexity of both natural and technical aqueous interfaces, self-assembled monolayers provide a platform for controllably tuning the chemical composition of the surface and thus the water restructuring. Here, we study a hydrophobic monolayer, a hydrophilic monolayer, and a mixed hydrophobic/hydrophilic monolayer in contact with water. Monolayers composed of both hydrophilic and hydrophobic chains mimic the complex and heterogeneous chemical composition of natural and technological surfaces. By employing heterodyne-detected sum frequency generation, the purely absorptive vibrational line shape of interfacial water is measured experimentally. We examined the structure of the interfacial water in contact with each of the monolayers by analyzing the relative dipole moment orientations and fitting the imaginary component of χ(2) with a combination of Lorentzian and Gaussian line shapes. For all of the monolayers, the hydrogen-bonded water points toward the monolayer, which is opposite of the orientation of the hydrogen-bonded water at the air-water interface. Additionally, a strongly hydrogen-bonded water species exists for the monolayers containing hydrophilic chains. The spectroscopic results suggest that the microscopic water structure in contact with the mixed monolayer is dominated by the hydrophilic parts of the monolayer, while the contact angle shows that at the macroscopic level the surface properties lie closer to the pure hydrophobic monolayer. [ABSTRACT FROM AUTHOR]

Purpose: This report intends to review the global burden of oral disease among older people and to examine their oral health needs. The evidence on the inter-relationships between poor oral health conditions of older people, general health and quality of life is highlighted. Finally, WHO strategies to improve oral health of older people are reviewed.Methods: The information relevant to this review was extracted from the WHO Global Oral Health Data Bank, the PubMed database, and the Cochrane Library. Surveys were carried out according to the criteria recommended by the WHO epidemiological manual Oral Health Surveys - Basic Methods. In addition, global data were sought on coverage of oral health care among older people. Finally, WHO policy documents on health care for aged people were gathered through the WHO website.Results: Across the globe, many older people suffer from oral pain or discomfort. Poor oral health during old age is mostly manifest in high caries experience, high prevalence rates of advanced periodontal disease, severe tooth loss, dry mouth, and oral pre-cancer/cancer. In both developing and developed countries, the burden of disease is particularly high among underprivileged and disadvantaged older people. In numerous countries, high proportions of the aged population are not covered by primary oral health care; this is mainly the case in low and middle income countries due to a critical shortage of dentists.Conclusions: In 2015, the WHO published the World Report on Ageing and Health, which outlines a framework for action to foster healthy ageing. The policies are highly relevant to the improvement of oral health. Transformation of oral health systems away from a disease-based curative model and towards disease prevention, as well as the provision of older-person-centred integrated care are required. Moreover, wide-ranging public health action on ageing is urgently needed. [ABSTRACT FROM AUTHOR]

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