Physicochemical and Photocatalytic Properties under Visible Light of ZnO-Bentonite/Chitosan Hybrid-Biocompositefor Water Remediation

In this investigation, a hybrid-biocomposite “ZnO-Bentonite/Chitosan” was synthesized using inexpensive and environmentally friendly materials (Bentonitechitosan) and (ZnO). It was used as a photocatalyst for water remediation. The structural, optical, thermal, and morphological properties of the synthesized hybrid-biocomposite were investigated using XRD, FTIR spectroscopy, UV-vis diffuse reflectance spectroscopy, TGA, XPS, and SEM-EDS. The thermal measurements showed that the decomposition of CS was postponed progressively by adding PB and ZnO, and the thermal stability of the synthesized hybrid-biocomposite was improved. The characterization results highlighted strong interactions between the C–O, C=O, -NH2, and OH groups of chitosan and the alumina-silica sheets of bentonite on the one side, and between the functional groups of chitosan (-NH2, OH) and ZnO on the other side. The photocatalytic efficiency of the prepared hybrid-biocomposite was assessed in the presence of Methyl Orange (MO). The experiments carried out in the dark showed that the MO removal increased in the presence of Zn-PB/CS hybrid-biocomposite (86.1%) by comparison with PB (75.8%) and CS (65.4%) materials. The photocatalytic experiments carried out under visible light showed that the MO removal increased 268 times in the presence of Zn-PB/CS by comparison withZnO.The holes trapping experiments indicated that they are the main oxidative active species involved in the MO degradation under both UV-A and visible light irradiations.

Impact of Short-Cut SWCF Yarn on Conductivity and Electrical Heatability of Silicone–MWCNT Composites

The incorporation of MWCNTs in polymer systems up to the percolation range renders them electrically conductive. However, this conductivity is not high enough for heating applications in the low-voltage range (<24 V). The combination of nanoscaled MWCNTs with microscaled short SWCNT fibers that was investigated in this study causes an abrupt rise in the conductivity of the material by more than an order of magnitude. Silicone was used as a flexible and high-temperature-resistant matrix polymer. Conductive silicone coatings and films with SWCF contents of 1.5% to 5% and constant MWCNT contents of 3% and 5% were developed, and their electrical and thermal properties in the voltage range between 6 and 48 V were investigated. The electrical conductivity of 3% MWCNT composite materials rose with a 5% addition of SWCFs. Because of this spike in conductivity, output power of 1260 W/m2 was achieved, for example, for a 100 µm thick composite containing 3% MWCNT and 4% SWCF at 24 V with a line spacing of 20 cm. Thermal measurements show a temperature increase of 69 K under these conditions. These findings support the use of such conductive silicone composites for high-performance coatings and films for challenging and high-quality applications.

Thermal and Residual Stress Distributions in Inconel 625 Butt-Welded Plates: Simulation and Experimental Validation

Thermal and residual stress distributions induced by the gas tungsten arc welding (GTAW) process on Inconel 625 were studied using numerical simulation and experiments. A multi-pass welding model was developed that uses a volumetric heat source. Thermomechanical analysis is carried out to assess the Thermal and residual stress distributions. Experiments were carried out with 5 mm thick Inconel 625 plates. X-ray diffraction techniques were used to measure residual stresses, and IR thermometry was employed to capture the temperature values on the welded joints. Simulations were performed with ANSYS numerical code, and a close agreement was found between the predicted and experimentally measured residual stress. Thermal measurements were collected pass by pass from the analysis, and the agreement was 9.08%. The agreement between the measured and analysed residual stress was 11%.

STRATEGI KENYAMANAN TERMAL MASJID AL-KAUTSAR KERTONATAN, KARTASURA, SUKOHARJO

Iklim tropis lembab di Indonesia menyebabkan rendahnya kecepatan angin, serta kelembapan dan suhu udara yang tinggi. Kelembapan tinggi menyebabkan sirkulasi udara tidak lancar dan berpengaruh pada kenyamanan termal. Masjid adalah bangunan untuk kegiatan ibadah, yang menuntut kenyamanan termal, selain kenyamanan audial. Upaya alat bantu penghawaan seperti kipas angin tidak akan bekerja optimal jika masjid tidak memiliki sistem sirkulasi udara yang baik. Masjid Al-Kautsar Kertonatan menarik untuk diteliti dari aspek penghawaan alami. Masjid berada di sudut pertigaan jalan kampung dan menghadap area persawahan. Saat masjid digunakan seluruh kipas angin dinyalakan, namun keluhan jamaah selalu muncul yaitu ketidaknyamanan termal, seperti rasa panas. Penelitian ini bertujuan untuk mengidentifikasi kualitas termal masjid Al-Kautsar Kertonatan, melalui metode kuantitatif pengukuran suhu udara, kelembapan udara dan kecepatan angin dengan alat thermohygrometer dan anemometer. Pengukuran termal dilakukan di dalam dan di luar ruang masjid secara bersamaan pada lima waktu salat. Selain pengukuran termal, dilakukan pula wawancara bebas kepada jamaah terkait kenyamanan termal. Hasil penelitian mengindikasikan pola aliran udara tidak merata dan tidak lancar di dalam ruangan, sehingga kualitas termal dalam kategori tidak nyaman dengan suhu udara rata-rata 31.0°C dan kecepatan angin rata-rata 0.1m/detik. Evaluasi subjektif mengindikasikan bahwa jamaah merasa nyaman apabila berada dekat jendela atau berada di tengah-tengah ruang, karena pada bagian itu aliran udara terasa. Solusi terbaik agar aliran merata di dalam ruang adalah redesain bukaan agar udara lebih banyak masuk, di samping itu perlu adanya penambahan vegetasi. MOSQUE THERMAL COMFORT STRATEGY (CASE STUDY OF AL-KAUTSAR MOSQUE, SUKOHARJO, CENTRAL JAVA) Indonesia's humid tropical climate causes low wind speed, as well as high humidity and air temperature. High humidity causes poor air circulation and affects thermal comfort. A mosque is a building for worship activities, which demands thermal comfort, in addition to audible comfort. Efforts for ventilation aids such as fans will not work optimally if the mosque does not have a good air circulation system. Al-Kautsar Kertonatan Mosque is interesting to study from the aspect of natural ventilation. The mosque is at the corner of the village road fork and overlooks the rice fields. When the mosque is used, all the fans are turned on, but complaints from the congregation always arise, namely thermal discomfort, such as feeling hot. This study aims to identify the thermal quality of the Al-Kautsar Kertonatan Mosque, through quantitative methods of measuring air temperature, humidity, and wind speed using thermohygrometer and anemometer. Thermal measurements are carried out inside and outside the mosque space simultaneously at five prayer times. In addition to thermal measurements, freed interviews were also conducted with the congregation regarding thermal comfort. The results indicate that the airflow pattern is not evenly distributed and not smooth so that the thermal quality is in the uncomfortable category with an average air temperature of 31.0°C and an average wind speed of 0.1m/second. The subjective evaluation indicated that pilgrims felt comfortable when they were near the window or in the middle of the room because in that part the airflow was felt. The best solution so that the flow is evenly distributed in the room is to redesign the opening to allow more air to enter, in addition to the need for additional vegetation.

Experimental and numerical investigations on heat transfer in fused filament fabrication 3D-printed specimens

A good understanding of the heat transfer in fused filament fabrication is crucial for an accurate stress prediction and subsequently for repetitive, high-quality printing. This work focuses on two challenges that have been presented when it comes to the accuracy and efficiency in simulating the heat transfer in the fused filament fabrication process. With the prospect of choosing correct thermal boundary conditions expressing the natural convection between printed material and its environment, values for the convective heat transfer coefficient and ambient temperature were calibrated through numerical data fitting of experimental thermal measurements. Furthermore, modeling simplifications were proposed for an efficient numerical discretization of infill structures. Samples were printed with varying infill characteristics, such as varying air void size, infill densities and infill patterns. Thermal measurements were performed to investigate the role of these parameters on the heat transfer and based on these observations, possible modeling simplifications were studied in the numerical simulations.

Thermal effects of thulium: YAG laser treatment of the prostate—an in vitro study

Purpose To objectively determine whether there is potential thermal tissue damage during Tm:YAG laser-based LUTS treatment. Methods Our experimental model was comprised of a prostatic resection trainer placed in a 37 °C water bath. In a hollowed-out central area simulating the urethral lumen, we placed a RigiFib 800 fibre, irrigation inflow regulated with a digital pump, and a type K thermocouple. A second thermocouple was inserted 0.5/1 cm adjacently and protected with an aluminum barrier to prevent it from urethral fluid. We investigated continuous and intermittent 120 W and 80 W laser application with various irrigation rates in eight measurement sessions lasting up to 14 min. Thermal measurements were recorded continuously and in real-time using MatLab. All experiments were repeated five times to balance out variations. Results Continuous laser application at 120 W and 125 ml/min caused a urethral ∆T of ~ 15 K and a parenchymal temperature increase of up to 7 K. With 50 ml/min irrigation, a urethral and parenchymal ∆T of 30 K and 15 K were reached, respectively. Subsequently and in absence of laser application, prostatic parenchyma needed over 16 min to reach baseline body temperature. At 80 W lower temperature increases were reached compared to similar irrigation but higher power. Conclusions We showed that potentially harming temperatures can be reached, especially during high laser power and low irrigation. The heat generation can also be conveyed to the prostate parenchyma and deeper structures, potentially affecting the neurovascular bundles. Further clinical studies with intracorporal temperature measurement are necessary to further investigate this potentially harming surgical adverse effect.