Engineering MIL-88B crystallites for enhanced H2 uptake capacity: The role of ultramicropores

In this study, a strategy that optimizes the pore size to enhance the adsorbed H₂ amount (at 298 K) is investigated. Pore size and ultramicropore fraction (ultramicropore volume/total pore volume) were controlled by Fe:TPA ratio. The highest H₂ adsorption capacity of 0.47 wt% (298 K and 7.6 bar) belongs to MIL-88B-3, which is higher than those of reported metal-organic frameworks (MOFs) (MIL-100, MIL-101 [Cr], HKUST-1, MOF-5, and ZIF-8). The enhanced H₂ sorption capacity (1.96 times) is a consequence of the high fraction (89%) and volume (0.22 cm³/g) of ultramicropores with pore diameters of 0.6 nm. Our results demonstrate that pore size, fraction, and volume of ultramicropores control the amount of H₂ adsorbed also at 298 K. With the use of perturbation assisted nanofusion synthesis strategy that introduces textural pores to the pore structure, a Brunauer-Emmett-Teller (BET) surface area higher than those of reported MIL-88Bs has been achieved, and a strategy to synthesize MOFs with enhanced H₂ sorption capacities is suggested.     

A novel design of high performance multilayered cylindrical dielectric lens antenna using 3D printing technology

In this work, design and realization of high performance, low‐cost X‐band multilayered cylindrical dielectric lens antenna (MLCDLA) is presented using 3D printing technology. Firstly, MLCDLA is designed and simulated in the complete 3D CST microwave studio (MWS) within the X‐ band as consisting of six layers and being fed through a conventional rectangular waveguide (WR90). These layers are in the form of cylindrical discs having different radii, thicknesses and made of a cheap polylactic acid material. These layers have also varying dielectric constant from 1.2 to 2.7 that are compatible for fused deposition modeling (FDM) based 3D‐printing process. Secondly, a prototype of MLCDLA is produced by using a FDM based 3D‐printer. 3D printed dielectric lens antenna is measured and a good return loss of almost more than 10 dB within the X‐band with a high gain of 16‐18 dBi are achieved as compared with the counterpart alternative designs. Thus, it can be concluded that the proposed novel design and prototyping method not only achieves the high radiation performance characteristics along X‐band but also is a fast, low‐cost, and effective method for prototyping dielectric lens structures for the microwave applications.     

Highly dependable concurrent programming using design for verification

There has been significant progress in automated verification techniques based on model checking. However, scalable software model checking remains a challenging problem. We believe that this problem can be addressed using a design for verification approach based on design patterns that facilitate scalable automated verification. In this paper, we present a design for verification approach for highly dependable concurrent programming using a design pattern for concurrency controllers. A concurrency controller class consists of a set of guarded commands defining a synchronization policy, and a stateful interface describing the correct usage of the synchronization policy. We present an assume-guarantee style modular verification strategy which separates the verification of the controller behavior from the verification of the conformance to its interface. This allows us to execute the interface and behavior verification tasks separately using specialized verification techniques. We present a case study demonstrating the effectiveness of the presented approach.     

Microstrip tapered traveling wave antenna for wide range of beam scanning in X‐ and Ku‐bands

In this work, a broadband traveling wave antenna (TWA) is presented as a microstrip design that is capable of a wide range of beam scanning by changing the operation frequency within 8 to 14 GHz. For this purpose, a rhombus shaped microstrip patch is used as a unit element and TWA is built as a tapered microstrip line consisting of the cascaded rhombus shaped unit elements and terminated by a rectangular antenna instead of traditional resistive termination which can be called patch loaded traveling wave antenna (PLTWA). Optimization and simulation of the PLTWA is carried out using 3‐D Microwave simulation software CST and its dimensions are resulted as 130 × 30 mm. From the simulations, it should be noted that the patch termination increases the maximum gain almost 3 dB and the total efficiency up to 90% compared to the traditional resistive load over the operation band at the expanse of a small distortion on S₁₁ characteristics. Then the PLTWA is fabricated and measured along its operation band 8 to 14 GHz and it exhibits a peak gain of 9.5 dBi at 11 GHz. The measured gain of the proposed antenna is found between 9 dB and 12 dB and its beam direction is steerable with the range of 80° (?65°‐15°) over the operation band 8 to 14°GHz.     

Catalytic effects of borax and iron(III) chloride on supercritical liquefaction of Anchusa azurea with methanol and isopropanol

Anchusa azurea is a lignocellulosic gramineous plant, and it has been selected as a renewable feedstock to be used in a liquefaction process to obtain biofuel. Milled Anchusa azurea stalks were converted to liquid products in methanol and isopropanol with (borax or iron(III) chloride) and without catalyst in an autoclave at temperatures of 260, 280, and 300°C. The liquefaction parameter effects such as catalyst, solvents, and temperature were investigated. The highest percentages of liquid yields from methanol and isopropanol conversions were 64.70% (with borax) and 29.20% (with borax) at 300°C in the catalytic runs, respectively. The highest conversion (73.80%) was obtained in methanol with borax catalyst at the same temperature. The obtained liquid products at 300°C were analyzed and characterized by elemental, Fourier transform infrared spectroscopy and gas chromatography–mass spectrometry (GC-MS). Seventy-three different compounds have been identified by GC-MS in the liquid products obtained in methanol at 300°C.     

Gel casting of mullite for radome applications

Gel-casting method was used to fabricate mullite ceramics because this method has not been applied to fabricate dense mullite in literature. Gel-casting parameters such as monomer types (acrylamide and metyhlenebisacrylamide), effect of initiator (ammonium persulfate), and catalyst (tetramethylenediamine) were studied. All samples reached to relative densities of 97% to 98.2% after sintering at 1540°C for 2 hours. Backscattered SEM images revealed anisotropically grown mullite grains, glassy phase located at triple junctions, hexagonally-shaped and faceted Al₂O₃ grains, and white-color grains consisting of ZrO₂ and undissolved TiO₂. A Weibull modulus of 12.33 (ie, indicating tough ceramics) and characteristic strength of 186 MPa were calculated, below which no failure was expected. A critical quenching temperature was found as about 400°C (ΔT ~ 380°C) by indentation-quench method. In addition, a thermal shock resistance parameter (eg, R in °C) of 142.4°C was calculated, which was higher than commonly used Al₂O₃ ceramics. Lower dielectric constant and loss are desired for wide frequency band application and shorter signal transmission delay time in radomes. The dielectric constant was found as nearly 7.5 up to 10 GHz and loss tangent was 0.0031 at 5 MHz. Dielectric and thermomechanical results suggest that mullite is a suitable candidate ceramic for radome applications.     

Interface-Based Specification and Verification of Concurrency Controllers

We present a modular approach to specification and verification of concurrency controllers by decoupling their behavior and interface specifications. The behavior specification of a concurrency controller defines how its shared variables change their values whereas the interface specification defines the order in which a client thread should call its methods. We show that the concurrency controllers can be designed modularly by composing their interfaces. We separate the verification of the concurrency controllers from the verification of the threads that use them. For the verification of the concurrency controllers we use infinite state verification techniques which enable us to verify controllers with parameterized constants and arbitrary number of user threads. We automatically generate Java monitors from the concurrency controller specifications which preserve the verified properties. For the thread verification we use finite state program verification tools which enable us to verify Java threads without any restrictions. We show that the user threads can be verified using stubs generated from the concurrency controller interfaces which improves the efficiency of the thread verification significantly.     

Growth and development impact of sustainable nutrition education: An experimental study

Healthy societies are formed by learning and maintaining sustainable healthy eating behaviors from childhood. The aim of this study was to determine the effect of short-term sustainable nutrition education on growth and development parameters of preschool children. This study is an experimental design with pretest–posttest control group. This study was carried out in two kindergartens between February 2022 and June 2023 in Turkey. The education group received 4 months of dietary behavior training. The dietary scale and anthropometric measurements were administered at the first and last meetings. Data were analyzed with 95% confidence interval. The study was completed with 174 children. A statistically significant difference was found, especially in body weight (p < 0.05) and body weight percentile values (p < 0.05) in the posttest of the education group. A statistically significant difference (p < 0.05) was found between the groups in the eating behavior scale posttest score. Nutrition education in schools is important in promoting healthy eating habits. Nutrition education improves eating behavior positively. To maintain healthy eating behaviors, however, the continuity of education is necessary. In addition, as growth and development are physical processes, it is recognized that growth and development cannot be assessed by nutrition alone.