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Hydrogen-containing materials are of fundamental as well as technological interest. An outstanding question for both is the amount of hydrogen that can be incorporated in such materials, because that determines dramatically their physical properties such as electronic and crystalline structure. The number of hydrogen atoms in a metal is controlled by the interaction of hydrogens with the metal and by the hydrogen-hydrogen interactions. It is well established that the minimal possible hydrogen-hydrogen distances in conventional metal hydrides are around 2.1 Å under ambient conditions, although closer H-H distances are possible for materials under high pressure. We present inelastic neutron scattering measurements on hydrogen in [Formula: see text] showing nonexpected scattering at low-energy transfer. The analysis of the spectra reveals that these spectral features in part originate from hydrogen vibrations confined by neighboring hydrogen at distances as short as 1.6 Å. These distances are much smaller than those found in related hydrides, thereby violating the so-called Switendick criterion. The results have implications for the design and creation of hydrides with additional properties and applications.
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Pressure-induced effects in alkali hydrides are investigated using a plane-wave density functional theory method. For the first time, we have measured the inelastic neutrons scattering (INS) spectra of NaH at pressures 1 and 2 GPa and used it to validate INS simulated from the first-principles calculations using both local density approximation (LDA) and the generalized gradient approximation (GGA). We found that LDA describes lattice dynamics better compared to the GGA. Thermodynamic properties such as lattice parameters, bulk modulus, and their derivatives are calculated using full lattice dynamics theory within the quasi-harmonic approximation (QHA) for all alkali hydrides. Anharmonic effects are investigated for NaH from the molecular dynamics trajectories and are negligible at given temperature and pressures. We have shown that the phase-change pressures obtained from the equal Gibbs free-energy conditions for two phases compare well with the available experimental data and is the accurate phase-change criterion. This study corroborates INS as an important complementary tool in benchmarking first-principles calculations.
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Porcelain aorta, characterized by extensive calcification of the aortic wall is often associated with coronary calcification. It can pose an increased risk of thromboembolic complications during interventional and surgical procedures. We present a case of a 52-year-old female, a chronic smoker with dyslipidemia with complaints of exertional chest pain for past 6 months. She was diagnosed as a case of non-ST elevation myocardial infarction (NSTEMI) with multivessel CAD, with porcelain aorta and calcified coronaries based on abnormal ECG, elevated troponin and coronary angiography findings. Percutaneous transluminal coronary angioplasty (PTCA) was the treatment modality chosen considering the risk of thromboembolism with aortic manipulation during coronary artery bypass grafting (CABG). Repeat ECG after the procedure showed resolution of ST segment depression. Her hospital stay was uneventful. She was discharged on dual antiplatelet therapy, statin and metoprolol. One-week follow-up revealed normal ECG and blood reports, with further outpatient department visits scheduled every 3 months. Porcelain aorta and coronary calcification is a challenging case for cardiologists. PTCA if done meticulously could be preferable to coronary-artery by-pass grafting (CABG) in such patients. Despite the risks like aortic rupture and thromboembolic complications, PTCA in a case of multivessel CAD with porcelain aorta and calcified coronaries could be a life-saving procedure.
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Introduction: Cyanoacrylate, used as a topical adhesive for wound closure in clinical settings, can result in poor cosmetic outcome on application to skin. Lack of formal medical or dermatological training among social media influencers poses risks of improper diagnosis, incorrect treatments, ineffective home remedies, and potential self-injury or long-term skin effects, especially among adolescents. Case presentation: The authors present a case of a young girl with a persistent post-inflammatory hyperpigmentation after using cyanoacrylate on her chin as a home remedy to reduce her double chin problem after learning from a video on social media. Biopsy findings were consistent with post-inflammatory hyperpigmentation in dermis. Clinical discussion: Application of cyanoacrylate over skin can result in allergic reactions, burn injuries, infections, itching, skin blistering, and aesthetic issues. Persistent post-inflammatory hyperpigmentation can be a poor cosmetic outcome on application of cyanoacrylate over skin. Conclusion: Inadequate social media safety regulations require healthcare professionals to be aware of social trends among adolescents and to encourage them for open conversations and professional help-seeking during times of distress in this digital era.
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Introduction: Breast cancer is one of the most common cancers worldwide both in terms of incidence and mortality. Its incidence has been on an increasing trend in developing nations including Nepal, however, there is very limited evidence of its demographic profile in our setting. This study aimed to find out the prevalence of breast cancer among cancer patients visiting the Department of Internal Medicine of a tertiary centre. Methods: A descriptive cross-sectional study was conducted among cancer patients visiting the Department of Internal Medicine of a tertiary care centre using retrospectively collected data from 1 August 2022 to 30 July 2023 after obtaining ethical approval from the Institutional Review Committee. Histopathologically confirmed cancer patients were included and those with incomplete and duplicated data were excluded. A convenience sampling method was used. The point estimate was calculated at a 95% Confidence Interval. Results: Among 2067 cancer patients, the prevalence of breast cancer was 102 (4.93%) (4.00-5.87, 95% Confidence Interval). The mean age was 50.51±2.08 years. The most commonly affected age group was 40 to 60 years constituting 61 (59.80%) patients. Histologically, invasive breast cancer of no special type was the most common and was found in 91 (89.22%) patients. Conclusions: The prevalence of breast cancer was similar to other studies done in similar settings. Keywords: breast cancer; cross-sectional study; demography; malignancy; prevalence.
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Neoplasias da Mama , Humanos , Pessoa de Meia-Idade , Adulto , Feminino , Neoplasias da Mama/epidemiologia , Estudos Transversais , Estudos Retrospectivos , Nepal/epidemiologia , Projetos de Pesquisa , Centros de Atenção TerciáriaRESUMO
Spin-phonon coupling plays an important role in single-molecule magnets and molecular qubits. However, there have been few detailed studies of its nature. Here, we show for the first time distinct couplings of g phonons of CoII(acac)2(H2O)2 (acac = acetylacetonate) and its deuterated analogs with zero-field-split, excited magnetic/spin levels (Kramers doublet (KD)) of the S = 3/2 electronic ground state. The couplings are observed as avoided crossings in magnetic-field-dependent Raman spectra with coupling constants of 1-2 cm-1. Far-IR spectra reveal the magnetic-dipole-allowed, inter-KD transition, shifting to higher energy with increasing field. Density functional theory calculations are used to rationalize energies and symmetries of the phonons. A vibronic coupling model, supported by electronic structure calculations, is proposed to rationalize the behavior of the coupled Raman peaks. This work spectroscopically reveals and quantitates the spin-phonon couplings in typical transition metal complexes and sheds light on the origin of the spin-phonon entanglement.
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The general and practical inversion of diffraction data-producing a computer model correctly representing the material explored-is an important unsolved problem for disordered materials. Such modeling should proceed by using our full knowledge base, both from experiment and theory. In this paper, we describe a robust method to jointly exploit the power of ab initio atomistic simulation along with the information carried by diffraction data. The method is applied to two very different systems: amorphous silicon and two compositions of a solid electrolyte memory material silver-doped GeSe3. The technique is easy to implement, is faster and yields results much improved over conventional simulation methods for the materials explored. By direct calculation, we show that the method works for both poor and excellent glass forming materials. It offers a means to add a priori information in first-principles modeling of materials, and represents a significant step toward the computational design of non-crystalline materials using accurate interatomic interactions and experimental information.