Melting Temperature Values Research Articles

Preparation and Performance Analysis of Form-Stable Composite Phase Change Materials with Different EG Particle Sizes and Mass Fractions for Thermal Energy Storage.

The low thermal conductivity and leakage of paraffin (PA) limit its wide application in thermal energy storage. In this study, a series of form-stable composite phase change materials (CPCMs) composed of PA, olefin block copolymer (OBC), and expanded graphite (EG) with different particle sizes (50 mesh, 100 mesh, and 200 mesh) and mass fractions are prepared by melt blending. OBC as a support material could reduce PA leakage during melting, and EG as a thermally conductive filler can improve the thermal performance of PCMs. The microstructure characteristics and chemical and thermal properties of prepared CPCMs are tested and analyzed. The results show that PA/OBC and EG have good compatibility, and there is no chemical reaction with each other to generate new substances. Thermal conductivity can be significantly improved by adding EG, and it is greatly enhanced with the increase in EG particle size at the same EG mass fraction. Simultaneously, the addition of EG increased the melting temperature of CPCMs and decreased the solidification temperature as well; meanwhile, the values of melting temperature and solidification are also reversed for CPCMs compared to PA/OBC. There is an optimal content of EG to balance the thermal conductivity and heat storage capacity for CPCMs. The addition of OBC can provide a stable geometric construction, and the leakage will be further improved with the increase in EG content. Finally, the melting time of CPCMs containing EG-50, EG-100, and EG-200 with 4 wt % EG is shortened by 52.9, 41.1, and 37.5%, respectively, compared with PCMs without EG in the heat storage and release experiments. Also, the CPCMs with EG-50 have better thermal performance compared with the CPCMs of EG-100 and EG-200.

Comparison of the stability of Mucor-derived flavin adenine dinucleotide-dependent glucose dehydrogenase and glucose oxidase

Long-term stability at near-body temperature is important for continuous glucose monitoring (CGM) sensors. However, the stability of enzymes used in CGM sensors has often been evaluated by measuring their melting temperature (Tm) values and by short heat treatment but not at around 37°C. Glucose oxidase (GOD) is used in current CGM sensors. In this study, we evaluated the stability of modified Mucor-derived flavin adenine dinucleotide-dependent glucose dehydrogenase (designated Mr144-297) with improved thermal stability at medium to high temperatures and compared it with that of GOD. The Tm value of Mr144-297 was 61.6±0.3°C and was similar to that of GOD (61.4±1.2°C). However, Mr144-297 was clearly more stable than GOD at 40°C and 55°C. At 37°C, the stability of a carbon electrode with immobilized Mr144-297 was higher than that of an electrode with GOD. Our data indicate that Mr144-297 is a more suitable enzyme for CGM sensors than is GOD.

Oscillation and Stepwise of Hydrocarbon Melting Temperatures as a Marker of their Cluster Structure

The presence of melting temperatures oscillatory and stepwise changes for hydrocarbons four homologous series is demonstrated and analyzed. The oscillating dependence is manifesteds on the principle of «even-odd» molecules with different deviations from linearity. According to the working hypothesis, this is due to the presence of the matter smallest structural unit in the cluster form of with a certain coordination number. The oscillation of melting temperatures in hydrocarbons series is explained by the fact that clustering can occur both at the site of the final carbon in the molecule and at other carbons in the molecule chain, and this fact depends on the «even-odd» effect. Based on the known values of melting temperatures in homologous series, the clusters probable structure is assumed. It is shown that graphs for the calculated values of equivalent lengths of these clusters correlate with corresponding graphs for hydrocarbons melting temperatures. An approximation formula has been developed to predict melting temperatures of hydrocarbons based on the values of the equivalent length and the cluster molecular weight, which operates with an approximation coefficient of 0.997 and a mean deviation of 4.2 K.

Effect of Glycerin on Electrical and Thermal Properties of PVA/Copper Sulphate Gel Polymer Electrolytes

Copper-ion conducting gel polymer electrolyte (GPE) systems based on polymer poly(vinyl alcohol) (PVA) and copper sulphate salt doped with glycerin as plasticizer have been synthesized by using solution casting technique. Differential scanning calorimetry (DSC) is used to examine the thermal effect of glycerin on a polymer electrolyte. With the addition of various quantities of glycerin, as a plasticizer in pure PVA and PVA + 20 wt% CuSO4 polymer electrolyte shows a decrease in the values of melting temperature, glass transition temperature and percentage of crystallinity. From TGA curves, it is observed that thermal degradation of the glycerin doped polymer electrolyte is shifted towards lower temperature when compared to pristine PVA and the weight loss of the polymer electrolyte increases with increase of glycerin concentration. From DTG analysis, the temperature of maximum decomposition for PVA is 283.4 °C and it is decreased by the addition of 20 wt% CuSO4 and upon increased concentration of the plasticizer from 1 to 3 mL of glycerin. For pure PVA and PVA + 20 wt% CuSO4, ε′ decreases with increasing glycerin concentration and is lowest at 3 mL glycerin concentration. The maximum ionic conductivity obtained was 9.39 × 10− 4 S/cm for PVA + 20 wt% CuSO4 + 3 mL glycerin gel polymer electrolyte. The above results suggested that, the optimum conducting sample is suitable as separator in rechargeable batteries.

Effect of Compatibilizer on the Persistent Luminescence of Polypropylene/Strontium Aluminate Composites.

There is a demand for long afterglow composites due to their potential applications in nighttime signal boards, sensors, and biomedical areas. In this study, Polypropylene (PP)/strontium aluminate-based composites [SrAl2O4:Eu2+/Dy3+ (SAO1) and Sr4Al14O25: Eu+2, Dy+3 (SAO2)] with maleic anhydride grafted PP compatibilizer (PRIEX) were prepared, and their auto-glowing properties were examined. After UV excitation at 320 nm, the PP/5PRIEX/SAO1 composites showed green emission at 520 nm, and blue emission was observed for PP/5PRIEX/SAO2 around 495 nm. The intensity of phosphorescence emission and phosphorescence decay was found to be proportional to the filler content (SAO1 and SAO2). The FTIR analysis excluded the copolymerization reaction between the SAO1 and SAO2 fillers and the PP matrix during the high-temperature melt mixing process. The SAO1 and SAO2 fillers decreased the overall crystallinity of the composites without affecting the Tm and Tc (melting and crystallization temperature) values. The thermal stability of the composites was slightly improved with the SAO1 and SAO2 fillers, as seen from the TGA curve. Due to the plasticizing effect of the compatibilizer and the agglomeration of the SAO1 and SAO2 fillers, the tensile modulus, tensile strength, and storage modulus of the composites was found to be decreased with an increase in the SAO1 and SAO2 content. The decreasing effect was more pronounced, especially with the bulk-sized SAO2 filler.

Helicobacter pylori Is Present at Quantifiable Levels in Raw Vegetables in the Mediterranean Area of Spain

Vegetables are one of the main foodstuffs consumed in the Mediterranean diet. However, raw vegetables have been associated with relevant foodborne outbreaks worldwide. Accurate knowledge of the microbiological quantitative risks associated with these matrices is crucial in order to define effective control measures, avoiding the survival and dissemination of foodborne pathogens through the different food chain stages. The aim of the present study is the assessment of the prevalence of Helicobacter pylori (a unique carcinogenic biological agent recognized to date) on leafy vegetables (spinach, lettuce, and chard) by means of the detection of the specific pathogenicity vacA gene. A real-time quantitative polymerase chain reaction (qPCR) optimized approach was used to detect H. pylori-positive samples and the concentration of this pathogen (with a limit of detection equal to 10 cells). One hundred raw vegetable samples were acquired in markets corresponding to the Spanish Mediterranean area. Sliced vegetable leaves were homogenized and centrifuged, and DNA was extracted from the homogenates. qPCR results confirmed 20 out of 100 H. pylori-positive samples, with melting temperature (Tm) values in the range of 84.8–86.5 °C (TmvacA H. pylori = 85 °C). Amplicons were cut, purified, and sequenced to confirm the homology with the H. pylori vacA gene. A total of 17 out of 100 vegetable samples (12/45 (26.6%) lettuce, 2/21 (9.5%) spinach, and 3/34 (8.8%) chard samples) were finally confirmed as H. pylori-positive. Contamination levels were in the range of 1.5 ± 0.3 to 2.5 ± 0.1 log10 cycles (36–335 CFU/g leafy vegetables). Our results show that H. pylori is detected by qPCR at levels close to infectious doses in fresh vegetables, thus posing a food safety hazard.

An excimer ‘ON[sbnd]OFF’ switch based on telomeric G-quadruplex and rGO for trace thrombin detection

In the recent decade, GO has emerged as an amazing 2D nanomaterial for developing DNA-based biosensors due to its fluorescence quenching properties, whereas similar research based on rGO was reported rarely. Herein, a novel multi-pyrene functionalized G-rich DNA probe based on the screened rGO showed much higher fluorescence quenching efficiency and excimer emission than that of universal GO. Different from the universal thrombin detection of the G4-forming aptamer-TBA(GGTTGGTGTGGTTGG), the original telomeric sequence is used in this study. The excimer emission “ON-OFF” switch amplified the response of thrombin detection is as low as 50 units. Furthermore, for four pyrene moieties that are sited in a crowded steric circumstance, the melting temperature (Tm) values and molecular dynamics simulations showed a positive effect on duplex G-quadruplex or GDNA·cDNA stability, without disturbing its helix structure.

Enhancing the electrical and physical nature of high-voltage XLPE cable dielectric using different nanoparticles

The goal of this study is to see how different chemically modified nanoparticles affect the performance and characteristics of commercial cross-linked polyethylene (XLPE) as a polymeric insulator used in insulating power cables and to compare their properties in order to figure out what factors are most important in improving the XLPE properties. Silicon dioxide or silica, titanium dioxide, and zinc oxide nanoparticle are used in this study. Nanoparticles (NPs) amino silane surface modification was carried out to decrease nanoparticle aggregation and improve compatibility with the polymer matrix. The melt blending process was used to synthesize and develop XLPE nano-composites on an industrial scale with varying nanoparticle loading ratios (0.5, 2.0, 3.5, and 5.0 wt%). The morphology and size of all functionalized nanoparticles were explained. The morphology of the produced nano-composites and particle dispersion in the XLPE polymer matrix were studied using X-ray diffraction and field emission scanning electron microscopy. All samples' thermal, electrical, and mechanical properties are evaluated. The result shows the optimum values of melting temperature for functionalized XLPE nano-composites and it is seen that the functionalized XLPE/TiO2 samples have the highest value that increased by 6.85 °C over XLPE, but the smallest tensile strength and elongation values were observed. Also, the use of silica NPs gives maximum enhancement dielectric properties.

Thermal expansivity of NaCl and KCl at high temperatures

A new mathematical equation for temperature dependence of thermal expansivity of Alkali halides (NaCl and KCl) has been developed for high temperatures. This relation is used to calculate thermal expansivity of NaCl and KCl for temperature range 350K to 750K along with available values of melting temperature. The results obtained are compared with available data. A good agreement between calculated and available data verifies the validity of obtained relation

Effect of Size and Shape on Melting Temperature of Nanomaterials

A simple theoretical model is discussed to study the size and shape dependence of melting temperature of nanomaterials. The computed values of melting temperature under varying conditions of size and shape are compared with the available experimental data. The results are discussed in the presence of other models. The superiority of present model over the other is discussed. It is found that the model is quite capable to study the effect of size and shape on melting temperature and is far better than other models reported in the literature. Due to the simplicity and applicability of the theory it may be used for different types of nanomaterials of current interest.

Physicochemical Properties of Duck Feet Gelatin Powder Extracted with Acetic Acid

Physiochemical properties such as colour, amino acid composition, melting temperature and hydroxyproline content determines the quality of gelatin. In this study, 4% of acetic acid was used to produce gelatin powder from Pekin, Muscovy and Khaki Campbell duck feet. The duck feet gelatin powders were analysed for their physiochemical properties and compared with commercial bovine gelatin. For colour analysis, Pekin duck feet gelatin (PDFG) had the highest L* value (21.41), followed by Khaki Campbell duck feet gelatin (KCDFG, 20.57) and Muscovy duck feet gelatin (MDFG, 17.85). KCDFG and PDFG had the same a* values (redness) which was -0.05, while the a* value of MDFG was -1.49. Lastly, the b* values of duck feet gelatin powder were 6.17, 8.47 and 9.47 for PDFG, MDFG and KCDFG, respectively. Duck feet gelatin powder had a melting temperature value of 61.91°C, 48.62°C and 44.81°C for KCDFG, MDFG and PDFG, accordingly. PDFG had the highest hydroxyproline content, which was followed by KCDEG and MDFG with the values of 9.15, 8.00 and 7.63 g/100g, respectively. The main amino acids present in the duck feet gelatin powder were glycine (21.73%, 13.62%, 13.46% and 15.33%), proline (13.08%, 8.71%, 8.39% and 9.34%), hydroxyproline (12.57%, 8.05%, 7.84% and 9.39%) and alanine (8.79%, 5.77%, 6.03%, 6.65%) for CBG, KCDFG, MDFG and PDFG, respectively. Furthermore, the lowest amino acids observed were tyrosine, histidine, methionine and isoleucine. No trace of cysteine was observed. Pekin duck feet produced the best quality gelatin compared to Khaki Campbell and Muscovy duck feet.

One‐pot, one‐step, and selective terpolymerization of ethylene oxide, propylene oxide, and COS to copoly(thioether)s with tunable thermal properties

AbstractFacile construction of sulfur‐rich polymers using readily available raw chemicals is an area aggressively pursued but challenging. Herein we use common feedstocks of ethylene oxide (EO), propylene oxide (PO), and carbonyl sulfide (COS) to synthesize copoly(thioether)s which are traditionally produced from unpleasant and difficult to store episulfides. In this protocol, the EO/COS coupling selectively generates a pure poly(ethylene sulfide) (PES) with melting temperature (Tm) values up to 172°C and high yields up to 98%. The EO/PO/COS terpolymerization leads to the incorporation of soft poly(propylene sulfide) (PPS) and hard PES segments together, affording a random PES‐co‐PPS copoly(thioether) with the complete consumption of EO and PO. Additionally, by simply varying the EO/PO feeding ratio, the obtained copoly(thioether)s possess tunable thermal properties, Tm values in the range of 76–144°C, and excellent solubility. These copolymerizations are conducted in one‐pot/one‐step at industrially favored reaction temperatures of 100–120°C using catalysts of common organic bases, suggesting a facile and practical manner. Especially, the copoly(thioether) exhibits high refractive indices up to 1.68 owing to its high sulfur content, suggesting a broad application prospect in optical materials.

Development and characterization of polyvinyl alcohol filled with date palm midrib powder

Date palm ( Phoenix dactylifera L) is one of the most widely cultivated crops in different parts of Saudi Arabia. The midribs rich in cellulose, hemicellulose, and lignin are often burnt in the farms, causes severe environmental problems. In the present study, date palm midrib (DPM), these waste materials were powdered and incorporated into polyvinyl alcohol (PVA). Composites were prepared by varying the DPM loading (0–10 wt.%) using the solution casting method. Tensile and thermal properties were analyzed for the composites with respect to filler loading. Addition of DPM as filler enhanced the tensile modulus while an inverse effect was observed in the elongation values. Differential scanning calorimeter (DSC) analysis showed a gradual increase in melting temperature (Tm) and crystallinity values for PVA. Thermogravimetric analysis (TGA) indicated that the incorporation of DPM into PVA can increase the thermal stability of PVA. Morphology of the composites was performed using scanning electron microscopy (SEM).

The N-body interatomic potential for molecular dynamics simulations of diffusion in tungsten

Tungsten, as the most refractory metal, is applied in fusion reactor in parts subjected to high temperatures and strong neutron irradiation. These factors lead to intense diffusion processes causing degradation of the material. Experimental investigations under such conditions are usually highly complicated and cannot provide a comprehensive understanding of the occurring phenomena. Therefore, their combination with theoretical approaches is required. One of the most robust approaches to simulate diffusion processes is molecular dynamics simulations based on classical interatomic potentials. It allows modeling relatively large samples consisting of several grains, grain boundaries, dislocations, and other types of defects for a reasonable computational time. The reliable simulations of the diffusion process require interatomic potentials satisfying the following criteria: prediction of melting point and thermal expansion as close as possible to the experimental values because the diffusion coefficient strongly depends on the homologous temperature and size factor. In the present paper, we present the new interatomic potential for tungsten, developed within the N-body approach, which reproduces the experimental value of melting temperature (3695 K) and thermal expansion at temperatures up to a melting point. The calculated diffusion coefficient demonstrates adequate agreement with experimental results. The constructed potential is applicable for simulation of processes involving diffusion, one of which is the irradiation damage.

Performance Comparison of Multiplexed Fluorescent Resonance Emission Transfer Hybridization Probes Across Roche LightCycler® Real-Time PCR Systems for the Detection of Bartonella species

Abstract Introduction/Objective Molecular assays for Bartonella species are important in diagnosing infection and expediting patient treatment. Real time polymerase chain reaction (RT-PCR) using fluorescent resonance energy transfer (FRET) hybridization probes can be used to detect Bartonella species in blood and fresh/fixed tissue biopsies in RT-PCR instruments. Over time, new technologies and reagents are introduced and existing PCR primers and FRET probes must be re-validated on new platforms. This study aimed to compare the performance of a Bartonella RT-PCR assay using the sunsetting Roche LightCycler® 2.0 (Roche Diagnostics, Indianapolis, IN) and newer LightCycler® 480 RT- PCR instruments. Methods/Case Report DNA was extracted from 132 historically positive, whole organism spiked, and historically negative whole blood and formalin fixed paraffin embedded (FFPE) samples. Samples were run on the LightCycler® 2.0 using instrument specific LightCycler® FastStart DNA Master HybProbe enzyme and compared to results generated using the LightCycler® 480 and its instrument specific LightCycler® 480 Genotyping Master enzyme. During optimization, MgCl2 concentrations and thermocycling profiles were adjusted. Accuracy, specificity, inclusivity, and limit of detection studies were performed. Crossing point (Cp), melting temperature (Tm), fluorescent peak and fluorescent background values were compared between the two instruments. Results (if a Case Study enter NA) The agreement in accuracy between the LightCycler® 2.0 and the LightCycler® 480 was 100% for whole blood samples. For historically positive FFPE samples, LightCycler® 2.0 sensitivity and LightCycler® 480 sensitivity were 86% and 100%, respectively. Specificity and inclusivity of the assay were identical between the two instruments. The limit of detection in whole blood was 5-fold lower on the LightCycler® 480 (50 copies/µL) compared to the LightCycler® 2.0 (250 copies/µL). Mean Cp and fluorescent peak intensity values increased by 5.1% and 65-fold, respectively. Conclusion The study demonstrates similar performance and improved limit of detection for the Bartonella FRET hybridization probe RT-PCR assay on the LightCycler® 480 compared to the LightCycler® 2.0.

Purification and Conformational Characterization of a Novel Interleukin-2 Mutein.

Toxicity of high-dose IL-2-based therapies have motivated the development of the IL-2 mutein, which has low expansion properties for regulatory T lymphocytes. The development of two variants (A and B) for the IL-2 mutein purification as well as a conformational comparative study by Circular dichroism (CD) and fluorescence spectroscopy of these products were evaluated. For the first time, in our center, were used of DTT and 2% SDS in the solubilization step to decrease the aggregates on intermediate product, which favors that disulfide bridges are correctly formed during re-folding. A molecular weight of 18kDa to the monomeric form and of 25-37kDa to the oligomeric species were estimated by SDS-PAGE. IL-2 mutein showed similar far-UV CD spectral characteristic typical of cytokines with 41% of α-helix content. Batches obtained by Process B showed similar conformational features according near-UV CD and FS studies. However, those obtained by Process A differed in their folding. IL-2 mutein showed that conformational features by near-UV CD were affected by 2% SDS, no variations on secondary structure were observed. Melting temperature values by far-UV CD were higher than 95°C, indicating a high thermal stability. Finally, the drug product obtained by Process B showed similar conformational characteristics by near-UV CD and FS, and higher biological activity values (7.0×103ng/mL) in the cell proliferation assay with respect to Process A. Also, the recovery was 15% higher than in the Process A and exhibited a 78.48% of purity. Indeed, Process B was selected for the purification.

New insights into change of lens proteins’ stability with ageing under physiological conditions

BackgroundAge-related cataract, which presents as a cloudy lens, is the primary cause of vision impairment worldwide and can cause more than 80% senile blindness. Previous studies mainly explored the profile...

Enhanced Stability of Detergent-Free Human Native STEAP1 Protein from Neoplastic Prostate Cancer Cells upon an Innovative Isolation Procedure.

Background: The STEAP1 is a cell-surface antigen over-expressed in prostate cancer, which contributes to tumor progression and aggressiveness. However, the molecular mechanisms underlying STEAP1 and its structural determinants remain elusive. Methods: The fraction capacity of Butyl- and Octyl-Sepharose matrices on LNCaP lysates was evaluated by manipulating the ionic strength of binding and elution phases, followed by a Co-Immunoprecipitation (Co-IP) polishing. Several potential stabilizing additives were assessed, and the melting temperature (Tm) values ranked the best/worst compounds. The secondary structure of STEAP1 was identified by circular dichroism. Results: The STEAP1 was not fully captured with 1.375 M (Butyl), in contrast with interfering heterologous proteins, which were strongly retained and mostly eluted with water. This single step demonstrated higher selectivity of Butyl-Sepharose for host impurities removal from injected crude samples. Co-IP allowed recovering a purified fraction of STEAP1 and contributed to unveil potential physiologically interacting counterparts with the target. A Tm of ~55 °C was determined, confirming STEAP1 stability in the purification buffer. A predominant α-helical structure was identified, ensuring the protein’s structural stability. Conclusions: A method for successfully isolating human STEAP1 from LNCaP cells was provided, avoiding the use of detergents to achieve stability, even outside a membrane-mimicking environment.

Theoretical approach to explore structural, electronic, magnetic, elastic and thermal characteristics of Heusler alloys CoYTiZ (Z = Al, Ga, Si, Ge)

In this study, structural, electronic, magnetic, elastic and thermal properties of Co-based Quaternary Heusler alloys (QHAs) CoYTiZ ([Formula: see text], Ga, Si, Ge) have been investigated by Wien2k code. The calculations have been performed using full-potential linearized augmented plane wave (FP-LAPW) method. Generalized Gradient Approximation (GGA) method has been adopted. Structural properties have been explored for three different Wyckoff positions. From the geometry optimization calculations, it is concluded that all these alloys are stable in Type-III crystal structure. Moreover, magnetic phase optimization revealed ferro-magnetic (FM) phase as stable one. Results of electronic properties have shown metallic character for CoYTiAl, CoYTiGa, CoYTiGe while nearly half metal (HM) character for CoYTiSi. Magnetic moment obeys Slater Pauling rule (SP) for these alloys. To check out the mechanical stability, elastic properties have been investigated. Elastic parameters have shown the ductile nature of these alloys. The values for melting temperature ([Formula: see text] have confirmed the thermal stability of the studied alloys.

REGULARITIES OF CHANGES AND PREDICTION OF MELTING POINTS AND THERMOELECTRIC FIGURE OF MERIT FOR THE COMPOUNDS Tl4BIVC3 AND Tl9BVC6 (BIV – Si, Ge, Sn, Pb; BV – P, As, Sb, Bi; C – S, Se, Te)

The study is a continuation of the systematic investigation of the compounds which are the crystal chemical analogues of the Tl5Te3 structure, crystallizing in the tetragonal space groups I4/mcm or P4/ncc. The studies conducted by the staff of the Uzhhorod National University over the past decades have found that these compounds exhibit a number of physical properties that are promising for practical use in modern technology. The subject of this work was the relationship between some physicochemical properties of the ternary chalcogenide compounds, such as Tl4BIVC3 and Tl9BVC6 (where BIV = Si, Ge, Sn, Pb; BV = P, As, Sb, Bi; and C = S, Se, Te), and the average charge (Zave) of the compouns’ atomic nuclei. Some of the predicted values of the melting temperature presented in the work may correspond to the temperature of the peritectic (or other type) transformation, as the nature of the formation and properties of this type of compounds have not yet been studied.
 For the first time, based on the results of collecting the literature data, detailed analysis and conclusions from them, the predicted melting temperature (Tm) values for 24 chalcogenide compounds of the Tl4BIVC3 (I) and Tl9BVC6 (II) compositions were established. There are five separate groups of the ternary chalcogenides of the both aforementioned types with a linear dependence of the changes in properties in the coordinates Tm – Zave, which include the analogues with both space groups, P4/ncc and I4/mcm. The limiting range of the Zave values of transformation of the above compounds from the space group P4/ncc to the I4/mcm one has been established; the defined range is within the Zave of ~60-62. The ternary compounds Tl9P(As,Sb,Bi)S6, Tl9P(As)Se6, Tl4Si(Ge,Sn,Pb)S3 and Tl4Si(Ge,Sn)Se3 belong to the space group P4/ncc, while the chalcogenides Tl9P(As,Sb,Bi)Te6, Tl9Sb(Bi)Se6, Tl4Si(Ge,Sn,Pb)S3 and Tl4PbSe3 belong to the space group I4/mcm. There is a clear tendency to increase the value of the thermoelectric figure of merit ZT for individual thio-, seleno- and tellurium-derived compounds at the substitution of the elements Si → Ge → Sn → Pb. Similar changes in the ZT values were also found for the vast majority of the type (II) compounds at the P → As → Sb → Bi transitions. The exceptions to this trend are thio-, selenium- and tellurium bismuth derivatives.