Solid Source Research Articles

Half-life determination of 111Ag

111Ag is a radionuclide that can be generated by neutron capture on 110Pd and whose decay properties and production feasibility make it a potential therapeutic agent against arthritis. Due to the discrepancies of recent published values of the half-life of 111Ag with previous published works which are not thoroughly documented for detailed experiment procedures and uncertainty budgets evaluation, an independent redetermination of the 111Ag half-life value is required. In this work, a solid 111Ag source was prepared and repeatedly measured in a high purity Germanium (HPGe) detector to determine its half-life. In total, more than fifty measurements were performed over a period of 26.3 days, corresponding to ∼3.5 half-lives of 111Ag. The experimental method and corresponding uncertainty budget are presented. The result of 7.419(15) days is consistent with the recently published value, 7.423(13) days, by Collins et al. and deviates by 0.418% from the currently recommended value 7.45(1) days. A new recommend half-life value of 7.437(7) days was determined utilizing all available experimental values by a power-moderated mean (PMM) method.

Growth of Low-Defect Nitrogen-Doped Graphene Film Using Condensation-Assisted Chemical Vapor Deposition Method.

It is significantly important to modulate the electrical properties of graphene films through doping for building desired electronic devices. One of the effective doping methods is the chemical vapor deposition (CVD) of graphene films with heteroatom doping during the process, but this usually results in nitrogen-doped graphene with low doping levels, high defect density, and low carrier mobility. In this work, we developed a novel condensation-assisted CVD method for the synthesis of high-quality nitrogen-doped graphene (NG) films at low temperatures of 400 °C using solid 3,4,5-trichloropyridine as a carbon and nitrogen source. The condensation system was employed to reduce the volatilization of the solid source during the non-growth stage, which leads to a great improvement of quality of as-prepared NG films. Compared to the one synthesized using conventional CVD methods, the NG films synthesized using condensation-assisted CVD present extremely low defects with a ratio of from D- to G-peak intensity (ID/IG) in the Raman spectrum lower than 0.35. The corresponding total N content, graphitic nitrogen/total nitrogen ratio, and carrier mobility reach 3.2 at%, 67%, and 727 cm2V-1S-1, respectively. This improved condensation-assisted CVD method provides a facile and well-controlled approach for fabricating high-quality NG films, which would be very useful for building electronic devices with high electrical performance.

Adaptation of the Irscom social profitability indicator to the context of community radio in Colombia

The main objective of this research action is to highlight the process of adaptation, validation, and administration of the Indicator of social profitability in communication (Irscom, Indicador de rentabilidad social en comunicación) for the community and indigenous radio sector of Colombia, a country with over 700 community radio stations nationwide, and the first in Latin America/Abya Yala to legalize them. The Irscom, a registered trademark, was created by the LabCom­Andalucía group of the University of Malaga in 2012. Employing six categories and 33 variables, it reflects the working practice and dynamics of radio stations to achieve their objectives, awarding points subject to weightings and criteria linked to pertinence. A compendium of quantitative (questionnaire, weighting, and rankings) and qualitative methods (focus groups and semi-structured interviews) were applied in its development and administration. The sample for this pilot project (from the Ministry of Culture of Colombia, the Faculty of Communications of the University Minuto de Dios, Bogotá, and LabComAndalucía) consisted of 11 community radio stations, an indigenous community radio station declared to be of public interest, and four community radio networks within the country. The results confirmed that Irscom is an organic tool that, without substantial modifications to the original framework, and although designed for Spain, can be adapted to other international contexts so that different broadcasters may appreciate their strengths and weaknesses. It contributes to holistic reflection on the social profitability of these media within their broadcasting areas. In the short term, Irscom may be extended to other community radio stations in the country. In the medium term, this indicator can help the community and the indigenous sound sector to improve their social profitability and validate their activities with government and institutional agencies to defend their important work of social cohesion and the need for solid sources of financing. It can also contribute to better collective organization by joining interests, with the awarding of the Irscom seal of quality as an endorsement of its implementation and improvements.

Oxygen-Rich Graphene/ZnO2-Ag nanoframeworks with pH-Switchable Catalase/Peroxidase activity as O2 Nanobubble-Self generator for bacterial inactivation

The oxygen-rich organic/inorganic (reduced graphene oxide (rGO)/ZnO2-Ag) nanoframeworks as suppliers of O2 nanobubbles (NBs) with dual pH-and-temperature-sensitive behavior were developed to suppress bacterial growth. It was demonstrated that not only the rate but also the final product of oxygen-rich ZnO2 decomposition (to an intermediate product of H2O2) rate was dramatically controlled by pH adjustment. Furthermore, in the presence of Ag nanoparticles, ̇OH radical generation switched to O2 NBs evolution by shifting the pH from acidic to basic/neutral conditions, demonstrating an adjustable nanozyme function-ability between catalase and peroxidase-like activity, respectively. Antibacterial properties of the in-situ generated O2 NBs substantially enhanced against bacterial models including methicillin-resistant Staphylococcus aureus in the presence of rGO. In fact, deflecting the electrons from their main respiratory chain to an oxygen-rich bypath through rGO significantly stimulated reactive oxygen species (ROS) generation, combating bacteria more efficiently. Moreover, NIR laser irradiation-induced temperature rise (due to the inherent photothermal properties of rGO) facilitated ZnO2 decomposition and accelerated growth and collapse of NBs. The simultaneous microscale thermal and mechanical destructions induced stronger antibacterial behavior. These results hold great promises for designing simple organic/inorganic nanoframeworks as solid sources of NBs with tunable enzyme-like ability in response to environmental conditions suitable for forthcoming graphene-based bio-applications.

High-temperature continuous-wave operation of 1310 nm InAs/GaAs quantum dot lasers

Here we report 1.3 μm electrical injection lasers based on InAs/GaAs quantum dots (QDs) grown on a GaAs substrate, which can steadily work at 110 °C without visible degradation. The QD structure is designed by applying the Stranski–Krastanow growth mode in solid source molecular beam epitaxy. The density of InAs QDs in the active region is increased from 3.8 × 1010 cm−2 to 5.9 × 1010 cm−2. As regards laser performance, the maximum output power of devices with low-density QDs as the active region is 65 mW at room temperature, and that of devices with the high-density QDs is 103 mW. Meanwhile the output power of high-density devices is 131 mW under an injection current of 4 A at 110 °C.

Spatial-temporal characteristics of corrected total phosphorus pollution loads from agricultural non-point sources in Tuojiang River watershed, Sichuan Province of southwestern China.

Traditional method of estimating pollution loads may neglect the internal spatial heterogeneity of socio-economic driving factors, which can result in overestimate and underestimate of pollution loads. In this study, the corrected approach to estimating total phosphorus (TP) pollution load was proposed to explore its future variation to develop effective phosphorus pollution control strategies for water environment management. As the first-class tributary of the Yangtze River, the TP out of limits in the Tuojiang River is serious. Thus, based on the presently related basic datasets related to TP pollution load estimation, we firstly adopted the GM (1,1) model to predict their varied trends from 2021 to 2025. We then used the pollution emission coefficient method to calculate the TP pollution load. Moreover, considering the temporal and spatial heterogeneity of the pollutant generation coefficient, we further introduced population and GDP factors to further modify the pollutant generation coefficient to correct TP pollution load. Finally, we employed the exploratory spatial data analysis (ESDA) method to explore spatial distribution characteristics and spatial autocorrelation of TP pollution load from diverse pollution sources in 2025. The results showed that the total TP pollution load from diverse pollution sources will increase from 12,194.92 t in 2021 to 12,461.26 t in 2025, an increase of 2.18%. More concretely, the TP pollution load from rural domestic sewage, rural domestic waste and livestock, and poultry pollution sources will separately decrease by 94.24 t, 77.9 t, and 86.52 t. However, the TP pollution load from agricultural runoff and agricultural solid wastes pollution sources will increase by 74.52 t and 451.49 t, respectively. The contribution of TP pollution load from diverse pollution sources to total TP pollution load will be as follows: livestock and poultry (63.49%) > agricultural solid wastes (16.72%) > agricultural runoff (12.26%) > rural domestic sewage (4.12%) > rural domestic waste (3.41%). The difference in the spatial distribution of TP pollution load from diverse pollution sources in 2025 will be prominent. TP pollution from rural domestic sewage and rural domestic waste pollution sources is more serious in the Xindu and Longquanyi districts, and that from agricultural runoff and agricultural solid wastes pollution sources is more prominent in the midstream and downstream. TP pollution load from livestock and poultry pollution source is higher in the Renshou, Anyue, Rongxian, Luxian counties, and Jiangyang district. Additionally, TP pollution load from rural domestic sewage, rural domestic waste, agricultural runoff, and agricultural solid wastes pollution sources in 2025 will show a clear spatial correlation, but the spatial correlation of TP pollution load from livestock and poultry pollution source will be weak. The study is effective to eliminate the influence of temporal and spatial variation of pollutants generates coefficients on TP pollution load estimation. The method can reflect the actual condition of pollution loads in watersheds more objectively, which can be applied to estimate other pollution loads of similar watersheds with intensive socio-economic activities. The findings in this study can provide a critical reference for the stakeholders to balance water environment conservation and socio-economic development.

Direct synthesis of Cu-SAPO-34 from solid phosphorus source for NH3-SCR reaction

Cu-SAPO-34 catalyst with CHA topology is widely used in the elimination of nitrogen oxides in automobile exhaust because of its excellent catalytic performance. A new method of directly synthesizing Cu-SAPO-34 from a new raw material instead of the original phosphorus source (phosphoric acid) was proposed. The new raw material AlPO4 can also act as an aluminum source in addition to serving as a phosphorus source. The two groups of samples took morpholine (MOR) and diethylamine (DEA) as templates respectively, and Cu-TEPA was used as Cu source to participate in the synthesis of the catalyst. The Cu-SAPO-34 catalysts had high NO conversion, and their activities were analyzed according to the characterization methods. The phase structure, active sites, strength of acid sites of Cu-SAPO-34 were analyzed by XRD, XPS, H2-TPR and NH3-TPD. In addition, the activity of directly synthesized Cu-SAPO-34 catalyst under different copper content and different template conditions was compared. The NO conversion of Cu0.05-SAPO-34-DT is 100% at 225–350 °C, while that of Cu0.05-SAPO-34-MT is more than 90% at 175–375 °C. As the raw material for direct synthesis of Cu-SAPO-34, AlPO4 not only reduces the synthesis cost, but also is more environmentally friendly.

Cost-effective preparation of layered tantalum oxynitrides for visible light-driven photocatalysis.

Layered oxynitrides are promising materials for visible light photocatalysis. However, the conventional method for the synthesis of oxynitrides using ammonia as a nitrogen source is dangerous. In this work, we successfully synthesized two layered tantalum oxynitrides, K1.35LaTa2O6.65N0.35 and K1.4Ca2Ta3O9.6N0.4, via a topochemical nitridation process using urea as a solid nitrogen source. Employing different characterization methods, we determined the structure and composition of layered oxynitrides. Furthermore, using Pt as a co-catalyst, these two layered oxynitrides showed excellent photocatalytic performances under visible light irradiation. In contrast to ammonia, urea process provides easy access for the synthesis of layered oxynitrides and sheds new light on the design of effective visible light-driven photocatalysts.

COUPLED EFFECT OF SOLID FRACTION AND INTERNAL ENERGY SOURCE ON CONVECTIVE HEAT TRANSPORT IN THREE-LAYERED AIR-POROUS-AIR DOMAIN: COMPARISON WITH DIFFERENT TWO-LAYERED DOMAINS

This paper studies convective heat transport driven by a uniform internal energy source coupled with the solid fraction in the partial air-saturated porous domains bounded by the top and bottom impermeable thermally conductive surfaces. The consideration of the coupled effect distinguishes our work from the papers of previous authors. We provide a comprehensive numerical study of internal convection and compare results of the linear stability analysis for three distinct domains. The first domain is air-porous-air (APA), where the heat-generating porous matrix is between the upper and lower air layers. In the second air-porous (AP) domain, the air layer overlays the porous medium. In the third porous-air (PA) domain, the air layer underlays the porous medium. The bimodal marginal stability curves and regime map with a demarcation line between the local and large-scale convective flows are obtained only for the APA and AP domains due to the division of each domain into the upper unstably stratified and lower stably stratified parts. The local convection cannot originate in the PA domain because the air layer belongs to the lower stably stratified part. A remarkable destabilizing effect of additional air layers has been revealed. For example, at the fixed solid fraction of 0.1, we achieve a 40-fold reduction of the critical Darcy-Rayleigh number in the APA domain by increasing the depth ratio from 0 to 0.5, and by 14 times in the AP domain and only by 3.5 times in the PA domain. The destabilizing effect enhances with increases in the solid fraction.

Gas-free alkoxycarbonylation of aryl iodides in a phosphonium-based deep eutectic solvent with Mo(CO)6 as a solid CO source.

Pd-catalyzed alkoxycarbonylation of aryl iodides has been explored, for the first time, in phosphonium-based deep eutectic solvents under gas-free conditions, by using Mo(CO)6 as the CO source. The method allows the preparation of ethylene glycol and glycerol esters in high yields (up to 99%), short reaction times and under mild reaction conditions with a very low catalyst loading (0.5 mol%).

Palladium-catalyzed Heck/aminocarbonylation of alkene-tethered carbamoyl chlorides with nitro compounds for the synthesis of carbamoyl-substituted oxindoles.

A straightforward and efficient approach for the synthesis of carbamoyl-substituted oxindoles has been developed via a palladium-catalyzed Heck cyclization and reductive aminocarbonylation reaction of alkene-tethered carbamoyl chlorides with nitro compounds. The reaction showed good compatibility toward versatile functional groups, and both nitroarenes and nitroalkanes were well tolerated. Using Mo(CO)6 as a solid CO source, without external reductants, a broad range of carbamoyl-substituted oxindoles were obtained in moderate to high yields.

Direct synthesis of phthalimides via palladium-catalysed double carbonylation of o-dihaloarenes with nitroarenes.

The direct carbonylation of readily available nitro compounds is more attractive and straightforward than the use of traditional amines as nucleophiles. Herein, a practical palladium-catalysed double carbonylation of nitroarenes with o-dihaloarenes has been developed for the construction of various N-aryl phthalimides. Key to the success of this transformation is the use of Mo(CO)6, which acts as both a reducing agent and a solid carbonyl source. A wide range of nitroarenes and o-dihaloarenes as well as o-iodobenzoic acids reacted smoothly to give phthalimides in 27-94% yields.

Low-Temperature Synthesis of Nano-AlN Based on Solid Nitrogen Source by Plasma-Assisted Ball Milling

Plasma-assisted ball milling was carried out on the Al+C3H6N6 system and Al+C4H4N4 system, respectively. The phase structure, functional groups and synthesis mechanism were analyzed by XRD and FT-IR, and the differences in the synthesis process of nano-AlN with different solid nitrogen sources were discussed. The results show that C3H6N6 has a stable triazine ring structure, and its chemical bond is firm and difficult to break, so AlN cannot be synthesized directly by solid-solid reaction at room temperature. However, there are a large number of nitrile groups (-CN) and amino groups (-NH2) in C4H4N4 molecules. Under the combined action of plasma bombardment and mechanical energy activation, C4H4N4 molecules undergo polycondensation and deamination, so that the ball milling tank is filled with a large number of active nitrogen-containing groups such as N=, ≡N, etc. These groups and ball milling activated Al can synthesize nano-AlN at room temperature, with a conversion rate of 92%. SEM, DSC/TG analysis showed that the powder obtained by ball milling was formed by soft agglomeration of many fine primary particles about 50–80 nm. The surface morphology of the powder was loose and porous, and it had strong activity. After annealing at 800°C, the conversion rate of the Al+C4H4N4 system reached 99%.

Czechs and Slovaks in Russia in the late 19th — early 20th centuries: A view of a modern historian

Another monograph prepared by the famous Russian historian, specialist in Bohemian Studies E. P. Serapionova, dedicated to the Czechs and Slovaks in the Russian Empire in the late 19th — early 20th centuries, is an important publication in Slavic studies in Russia. The monograph, which has mostly a review character, takes fully into account the whole extensive historiography on this topic, including both the works of domestic historians and the works of Czech and Slovak researchers. The monograph, which has a solid source base, including a number of previously unused archival materials, analyzes in detail the initial stage of the migration of Czechs and Slovaks to Russia, starting from the Middle Ages. Justifiably, the author paid great attention to migration processes in the 19th century, when, for a number of reasons, the migration influx of Czechs and Slovaks to the Russian Empire increased sharply. E. P. Serapionova analyzes in detail the reasons for the migration of Czechs and Slovaks to Russia, emphasizing that among the reasons for the emigration of Czechs and Slovaks to Russia there were both political and religious ones, but economic considerations noticeably prevailed. The monograph reflects the active cultural and social life of the Czech colonies in Russia. The author separately explores and identifies the specifics of the Czech communities in Volhynia, Crimea and the North Caucasus, as well as in large cities of the Russian Empire, noting the active participation of Czechs in the sports movement and in the neo-Slavic movement at the turn of the 20th century. In general, the study of E. P. Serapionova is a successful continuation of the already existing extensive historiographical tradition. It represents a valuable contribution to the study of Russia’s relations with the Czechs and the Slovaks.

THE DEVELOPMENT OF TARJÎḤ METHOD IN ISLAMIC LAW: TRACING THE THOUGHTS OF MUḤAMMAD ‘ALÎ AL-SÂBÛNÎ IN RAWAÎ’ AL-BAYÂN

This article aims to trace the thoughts of Muhammad ‘Ali al-Sâbûni in attempt to develop the tarjîh method through the interpretation of ahkâm verses in Rawâî’ al-Bayân book. This is substantial to study since tarjîh is one of solutions taken by many ulama when there is a contradicting argument. Besides, the tarjîh principles used by al-Sâbûni have distinction compared to other ulama. This is library research included in qualitative study, implementing textual approach and Holsti’s version of content analysis. The analysis tools used in this article are tarjîh theories in usûl al-fiqh, both general theories of al-Shaukânî and al-Âmidi, which were then developed by Wahbah al-Zuhaili, as well as the application theories of tarjîh Ḥusain al- Ḥarbî. The results show that al-Sâbûni in Rawâî’ al-Bayân develops certain tarjîh principles and implements the method which is in accordance with those principles. In this case, there are 22 tarjîh principles and 16 implementation methods, taken from the solid source and basis such as Quran, hadith, theories in ‘ulûm al-Qur’ân and usûl al-fiqh, as well as the arguments of previous ulama. Implementation wise, al-Sâbûni is able to do innovative and objective tarjîh which are far from mazhab’s fanaticism.

Palladium-Catalyzed Domino Reaction for the Assembly of Norbornane-Containing Chromones with Dimethyl Squarate as the Solid C1 Source.

Reported herein is a novel palladium-catalyzed [2 + 2 + 1] domino annulation of 3-iodochromones, bridged olefins, and dimethyl squarate allowing the construction of chromone-containing polycyclic compounds in good to high yields. Importantly, dimethyl squarate is first employed as the solid C1 source in organic synthesis. Gram-scale experiments, late-stage modification of natural products, as well as transformations of products show potential for further synthetic elaborations.

Acyl Amidines by Pd-Catalyzed Aminocarbonylation: One-Pot Cyclizations and 11C Labeling.

A protocol for the carbonylative synthesis of acyl amidines from aryl halides, amidines, and carbon monoxide catalyzed by Pd(0) is reported herein. Notably, carbon monoxide is generated ex situ from a solid CO source, and several productive palladium ligands were identified with complementary benefits and substrate scope. Furthermore, sequential one-pot, two-step protocols for the synthesis of 1,2,4-triazoles and 1,2,4-oxadiazoles via acyl amidine intermediates are reported. In addition, this approach was extended to isotopic labeling using [11C]carbon monoxide to allow, for the first time, synthesis of 11C-labeled acyl amidines as well as a 11C-labeled 1,2,4-oxadiazole.

Influence of the solid titanium source on the activity of La1−xTixFeO3 photo-CWPO catalysts under UV-A light

In the search for more efficient low-temperature catalysts able to oxidise biorecalcitrant pollutants in water, the selective substitution of La3+ by Ti3+ cations was reported to boost the UV-A light driven activity of LaFeO3 orthoferrites as H2O2-mediated photo-CWPO catalysts. La1−xTixFeO3 catalysts with 0 < x < 0.11 were obtained by a modified Pechini sol–gel route via the addition of a solid source of titanium during the synthesis. By using a span of crystallized and amorphous TiO2, the influence of the titanium source on the substitution rate in the orthoferrite network and on the performances of the catalysts under UV-A light was demonstrated using the degradation of 4-chlorophenol as test reaction. The amorphous content of the TiO2 precursor is proposed to be the key factor driving the substitution of La3+, the largest substitution of 11 % being obtained using a dried sol-gel TiO2 precursor. We suggest that the substitution proceeds during the thermal treatment via a solid-solid diffusion between TiO2 and the amorphous LaFeO3 before it crystallises. The catalyst robustness was influenced by the TiO2 nature. Small size Ti-LaFeO3 crystallites strongly lowered or blocked the Fe release, while no improvement was observed for large size crystallites vs. the pristine material, what was associated to a poor homogenization of the titanium in the network. We showed that the mineralization activity was proportional to the substitution rate of La1−xTixFeO3 catalysts, while a similar relationship could be drawn for the degradation activity only in the case of highly robust catalysts with pure heterogeneous surface reactions.

Fuel scarcity or household wealth? Assessing the drivers of cooking energy consumption patterns in rural areas in East Africa

ABSTRACT Rural households in Tanzania and Mozambique depend mainly on charcoal, firewood and other traditional fuels, such as cow dung or agriculture by-products, to cook. Simultaneously, fuel scarcity is an important phenomenon that leads households to apply coping strategies such as reducing the number of meals or increasing walking distance to collect firewood. Despite the well-known negative health, economic and potential ecologic impacts, the transition away from solid biomass energy sources is not expected in the short run. Thus, understanding the patterns of biomass energy consumption is essential to allow sustainable development in the household cooking sector. In this study, we evaluated the influence of wealth status and fuelwood scarcity on household energy choices in four villages with case study sites in Mozambique and Tanzania. The fuel usage patterns are consistent with the ‘energy stacking’ model as, despite an increase in the consumption of charcoal, firewood remains the principal cooking fuel. Wealth does not necessarily result in a transition toward cleaner fuels, nor does scarcity result in the use of other forms of traditional bioenergy. We suggest the promotion of fuel reduction strategies such as improved cookstoves or the implementation of on-farm trees to reduce the pressure on forests.

Topology Optimization Design of Micro-Channel Heat Sink by Considering the Coupling of Fluid-Solid and Heat Transfer

To investigate the effect of the target weight coefficient on the structure design of the micro-channel heat sink, an innovative method for the topology optimization design of micro-channel structures with different bifurcation angles is adopted. In this study, the improved interpolation function, density filtering, and hyperbolic tangent projection methods are adopted to obtain a clear topological structure of the micro-channel heat sink. The heat transfer of the micro-channel heat sink under different bifurcation angles is compared. At the same time, the influence of the two different objective functions, heat transfer, and flow energy consumption, is analyzed in the topology optimization of micro-channel heat sinks. The results show that when the bifurcation angle is 135°, both the heat transfer and the average outlet temperature of the micro-channel heat sink obtain the maximum value, and the heat transfer effect is the best. With the increase of the heat transfer weighting coefficient, the distribution of solid heat sources in the main channel increases, and the refinement of the branch channels also increases. On the other hand, although the heat transfer effect of the micro-channel heat sink is the best, the corresponding flow energy consumption is larger.