Understanding the Metastability of Theophylline FIII by Means of Low-Frequency Vibrational Spectroscopy.

While theophylline has been extensively studied with multiple polymorphs discovered, there is still currently no conclusive structure for the metastable theophylline form III. In this present work, by combining more widely used techniques such as X-ray diffraction and thermogravimetric analysis with more emerging techniques like low-frequency Raman and terahertz time-domain spectroscopy, to analyze the structure and dynamics of a crystalline system, it was possible to provide further evidence that the form III structure has a theophylline monohydrate structure with the water molecules removed. Solid-state density functional theory simulations were paramount in proving that this proposed structure is correct and explain how vibrational modes within the crystal structures feature and govern polymorphic transitions and the metastable form III. Through the insight provided by both simulated and experimental results, it was possible to decisively conclude the elusive crystal structure of theophylline form III. It was also shown that the correct space group for theophylline monohydrate is not P21/n but, in fact, Pc.

Assessment of the Impact of a Daily Rehabilitation Program on Anxiety and Depression Symptoms and the Quality of Life of People with Mental Disorders during the COVID-19 Pandemic.

Community psychiatry is a modern and effective form of care for patients with mental disorders. The aim of the study was to assess the impact of a rehabilitation program at the Mental Health Support Centre in Tarnowskie Góry (Poland) on reducing severity of anxiety and depression symptoms, as well as improving overall quality of life during the COVID-19 pandemic. The study involved 35 patients, examined with an authors' questionnaire on sociodemographic data, the Hospital Scale of Anxiety and Depression (HADS) and the Short Form Health Survey (SF-36). Data was obtained during the first national lockdown and compared to data gathered before the pandemic on the same study group. Imposed restrictions, negative emotional state during lockdown, subjectively assessed higher health risk and a low level of knowledge about the COVID-19 pandemic did not significantly correlate with a severity of depression and anxiety, as well as general quality of life. However, the comparison of the results obtained in HADS and SF-36 scales show a significant improvement in both categories. Rehabilitation activities, including physical training, cognitive exercise and social therapy, reduce the severity of the symptoms and have a positive effect on the overall quality of life in patients suffering from schizophrenia and affective disorders. Therefore, holistic mental health support services may positively affect building an individual resilience. The severity of anxiety symptoms during the COVID-19 pandemic shows a negative correlation with the patient's age.

Identifying and explaining vibrational modes of quinacridones via temperature-resolved terahertz spectroscopy: absorption experiments and solid-state density functional theory simulations.

Quinacridone and its substituted analogs are pigments widely used in art and industry. The temperature dependence of the crystal structures of two quinacridone polymorphs (ß and γ), along with the common variant 2,9-dimethylquinacridone, were investigated using powder X-ray diffraction and terahertz spectroscopy. These were then compared with solid-state density functional theory simulations of both structures and vibrations. X-ray patterns were collected at eight temperatures in the range 13-298 K and terahertz spectra at fifteen temperatures in the range 20-300 K. Simulations were at absolute zero and at appropriate expansions to model room temperature. It was found that some of the powder X-ray diffraction features in only ß-quinacridone (15.7°, 19.7° and 31.2° at 13 K) underwent anomalous shifting with temperature change. We attribute this to the unique coplanar hydrogen bonding pattern of ß-quinacridone compared to the other solids, with the unusual diffraction peaks originating from crystallographic planes perpendicular to the a axis intermolecular hydrogen bonds. This observation coincides with a contraction of the a axis with heating and results from its relatively weak N-HO hydrogen bonds and significant C-HH-C repulsions. Associated with this anomalous contraction, for ß-quinacridone only spectral peaks are seen to increase in energy with temperature.

Mapping the polymorphic transformation gateway vibration in crystalline 1,2,4,5-tetrabromobenzene.

The thermosalient behavior of 1,2,4,5-tetrabromobenzene (TBB) is related to a temperature-induced polymorphic structural change. The mechanism behind the phase transition has been investigated in this work using low-frequency (10-250 cm-1) Raman spectroscopy and solid-state density functional theory simulations. Careful adjustments of the probing laser power permitted thermal control of the polymorph populations and enabled high-quality Raman vibrational spectra to be obtained for both the ß (low temperature) and γ (high temperature) forms of TBB. Numerous well-defined vibrational features appear in the Raman spectra of both polymorphs which could be assigned to specific motions of the solid-state TBB molecules. It was discovered that the lowest-frequency vibration at 15.5 cm-1 in ß-TBB at 291 K is a rotational mode that functions as a gateway for inducing the polymorphic phase transition to γ-TBB, and serves as the initiating step in the storage of mechanical strain for subsequent macroscopic release. Computationally mapping the potential energy surface along this vibrational coordinate reveals that the two TBB polymorphs are separated by a 2.40 kJ mol-1 barrier and that γ-TBB exhibits an enhanced cohesion energy that stabilizes its structure.

Methyl-rotation dynamics in metal-organic frameworks probed with terahertz spectroscopy.

In ZIF-8 and its cobalt analogue ZIF-67, the imidazolate methyl-groups, which point directly into the void space, have been shown to freely rotate - even down to cryogenic temperatures. Using a combination of experimental terahertz time-domain spectroscopy, low-frequency Raman spectroscopy, and state-of-the-art ab initio simulations, the methyl-rotor dynamics in ZIF-8 and ZIF-67 are fully characterized within the context of a quantum-mechanical hindered-rotor model. The results lend insight into the fundamental origins of the experimentally observed methyl-rotor dynamics, and provide valuable insight into the nature of the weak interactions present within this important class of materials.

Optical Properties of Meloxicam in the Far-Infrared Spectral Region.

One of the most commonly used nonsteroidal anti-inflammatory active pharmaceutical ingredient called Meloxicam has been characterized spectroscopically both by Terahertz (THz) time domain spectroscopy (THz-TDS) and by Fourier Transform Infrared (FTIR) spectroscopy in far-IR regions of electromagnetic spectrum; 0.2 THz to 20 THz. While many relatively sharp features are observed in the far-IR range between 2 THz to 20 THz as expected for being an organic substance, very distinct and relatively strong absorption bands are also observed at 1.00, 1.66, 2.07 and 2.57 THz in the THz range. These well separated, defined, and fairly strong spectral features can be used for discrimination and quantification of Meloxicam in drug analysis. Frequency dependent refractive index of the drug was determined in a range of 0.2 THz and 2.7 THz, where an almost constant index was observed with an average index of 1.75. Powder XRD, and solid-state Density Functional Theory (SS-DFT) calculations were utilized to determine the crystalline form of the Meloxicam sample in its enolic crystalline form. Single molecule DFT calculations were also performed in all four possible structures of Meloxicam. In addition, the capability of THz waves transmission through common packaging materials is demonstrated for possibility of future on-site analysis. The results suggest that drug analysis will be possible to perform not only at every stage of manufacturing without destruction but also directly at the shelf of a market after development of portable THz technologies.

Distinguishing Quinacridone Pigments via Terahertz Spectroscopy: Absorption Experiments and Solid-State Density Functional Theory Simulations.

Through a combined experimental and theoretical investigation we determine that the fundamental modes of three quinacridones fall in the terahertz spectral range (1-10 THz, ∼30-300 cm-1). In each spectrum the terahertz resonances correspond to wagging, rocking, or twisting of the quinacridone rings, with the most intense absorption being an in-plane rocking vibration of the carbonyl oxygens. In spite of these spectral similarities, we demonstrate that terahertz measurements readily differentiate ß-quinacridone, γ-quinacridone, and 2,9-dimethylquinacridone. The spectrum of ß-quinacridone has a group of closely spaced modes at ∼4 THz, whereas in contrast the spectrum of γ-quinacridone displays a widely spaced series of modes spread over the range ∼1-5 THz. Both of these have the strongest mode at ∼9 THz, whereas in contrast 2,9-dimethylquinacridone exhibits the strongest mode at ∼7 THz. Because quinacridones are the basis of widely used synthetic pigments of relatively recent origin, our findings offer promising applications in the identification and dating of modern art.

Impact of family and school environment on the development of social anxiety disorder: a questionnaire study.

BACKGROUND: Social anxiety disorder (SAD) is a very common condition, although its prevalence is believed to be underestimated. The affected subjects often have trouble to search for support. The onset occurs mainly in early adolescence. The aim of this paper was to evaluate the impact of school and family background on the development of SAD. SUBJECTS AND METHODS: Our survey, available on a popular social network site, was divided into 4 parts: 1) demographic data (gender, age, site of residence), 2) genetic and organic background (comorbid mental disorders, addictions), 3) situation at school and in the family environment during adolescence, 4) the part designed to define the group that may suffer from SAD with the use of the Mini-Social Phobia Inventory (Mini-SPIN). RESULTS: 226 people were recruited. The age range was 16-61, with the average of 25,8. 71% of the respondents lived in cities with a population of more than 100 000. Male to female ratio was 3:1. According to Mini-SPIN 26,5% of the interviewees might suffer from SAD (28.2% of women and 21.4% of men). Our study showed, that both family and school environment factors have an influence on the development of SAD. It was shown that the especially important risk factors are bad relations with peers and being an object of derision at school. CONCLUSION: The percentage of network community users that are likely to suffer from SAD, significantly exceeds the clinical data. Both family and school environment factors were shown to be risk factors for the development of this disorder.