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The purpose of this paper is to investigate the performance of Passive Direct Methanol Fuel Cell (PDMFC) experimentally using various Membrane Electrode Assembly (MEA) shapes such as square, rectangle, rhombus, and circle with equal areas and equal perimeters. The variation in MEA shape/size is achieved by altering gasket openings in the dynamic regions.

In the equal areas of MEA shapes, gasket opening areas of 1963.5 (+/−0.2) mm2 are used. Whereas in the equal perimeters of shapes, gasket opening perimeters of 157.1 (+/−0.2) mm are used. In this experimentation, Nickel-201 current collectors with 45.3% of circular openings are used on both the anode and cathode sides. The experiment is carried out at a 5 molar methanol concentration to find out the highest power density of the cell.

In the equal areas, among the shapes that are chosen for investigation, the square shape opening consisting of a perimeter of 177.2 mm has developed a maximum power density of 6.344 mWcm⁻² and a maximum current density of 65.2 mAcm⁻². Similarly, in equal perimeters, the rhombus shape opening with an area of 1400 mm2 has developed a maximum power density of 7.714 mWcm⁻² and a maximum current density of 85.3 mAcm⁻².

The novelty of this research work is instead of fabricating various shapes and sizes of highly expensive MEAs, the desired shapes and sizes of the MEA are achieved by altering gasket openings over dynamic regions to find out the highest power density of the cell.

Some studies have been reported in the past on diaphragmatic hernia (DH) surgery techniques using additive manufacturing (AM) technologies, symptoms of a hernia and post-surgery complications. But hitherto little has been reported on bibliographic analysis (BA) for health monitoring of bovine post-DH surgery for long-term management. Based on BA, this study aims to explore the sensor fabrication integrated with innovative AM technologies for health monitoring assistance of bovines post-DH surgery.

A BA based on the data extracted through the Web of Science database was performed using bibliometric tools (R-Studio and Biblioshiny).

After going through the BA and a case study, this review provides information on various 3D-printed meshes used over the sutured site and available Internet of Things-based solutions to prevent the recurrence of DH.

Research gaps exist for 3D-printed conformal sensors for health monitoring of bovine post-DH surgery.

This paper aims to propose a single element, dual feed, polarisation diversity antenna. The proposed antenna operates from 2.9 to 10.6 GHz for covering the entire ultra-wideband (UWB) frequency range. The antenna is designed for usage in massive multiple input multiple output (MIMO) and closed packaging applications.

The size of the antenna is 24 × 24 × 1.6 mm³. The radiating element of the antenna is derived from the Sierpinski–Knopp (SK) fractal geometry for miniaturization of the antenna size. The antenna has a single reflecting stub placed between the two orthogonal feeds, to improve isolation.

The proposed antenna system exhibits S₁₁ < −10 dB, S₂₁ < −15 dB and stable radiation characteristics in the entire operating region. It also offers an envelope correlation coefficient < 0.01, a diversity gain > 9.9 dB and a capacity loss < 0.4 bps/Hz. The simulated and measured outputs were compared and results were found to be in similarity.

The proposed UWB-MIMO antenna has significant size reduction through usage of SK fractal geometry for radiating element. The antenna uses a single radiating element with dual feed. The stub is between the antenna elements which provide a compact and miniaturized MIMO solution for high density packaging applications. The UWB-MIMO antenna provides an isolation better than −20 dB in the entire UWB operating band.

This paper aims to realize the vertical interconnection in 3D radio frequency (RF) circuit by coaxial transitions with broad working bandwidth and small signal loss.

An advanced packaging method, 12-inch wafer-level through-mold-via (TMV) additive manufacturing, is used to fabricate a 3D resin-based coaxial transition with a continuous ground wall (named resin-coaxial transition). Designation and simulation are implemented to ensure the application universality and fabrication feasibility. The outer radius R of coaxial transition is optimized by designing and fabricating three samples.

The fabricated coaxial transition possesses an inner radius of 40 µm and a length of 200 µm. The optimized sample with an outer radius R of 155 µm exhibits S11 < –10 dB and S21 > –1.3 dB at 10–110 GHz and the smallest insertion loss (S21 = 0.83 dB at 77 GHz) among the samples. Moreover, the S21 of the samples increases at 58.4–90.1 GHz, indicating a broad and suitable working bandwidth.

The wafer-level TMV additive manufacturing method is applied to fabricate coaxial transitions for the first time. The fabricated resin-coaxial transitions show good performance up to the W-band. It may provide new strategies for novel designing and fabricating methods of RF transitions.

This paper aims to investigate the effect of partially blocking the cathode channel with the stair arrangement of obstacles on the performance of a proton exchange membrane fuel cell.

A numerical study is conducted by developing a three-dimensional computational fluid dynamics model.

As the angle of the stair arrangement increases, the performance of the fuel cell is reduced and the pressure drop is decreased. The use of four stair obstacles with an angle of 0.17° leads to higher power density and a lower pressure drop compared to the case with three rectangular obstacles of the same size and maximum height. The use of four stair obstacles with an angle of 0.34° results in higher power density and lower pressure drop compared to the case with two rectangular obstacles of the same size and maximum height.

Using the stair arrangement of obstacles as an innovation of the present work, in addition to improving the fuel cell’s performance, creates a lower pressure drop than the simple arrangement of obstacles.

This paper aims to propose a two-element dual fed ultra-wideband (UWB) multiple input multiple output (MIMO) antenna system with no additional decoupling structures. The antenna operates from 3.1 to 10.6 GHz. The antenna finds its usage in on-body wearable device applications.

The antenna system measures 63.80 × 29.80 × 0.7 mm. The antenna radiating element is designed by using a modified dumbbell-shaped structure. Jean cloth material is used as substrate. The isolation improvement is achieved through spacing between two elements.

The proposed antenna has a very low mutual coupling of S₂₁ < −20 dB and impedance matching of S₁₁ < −10 dB. The radiation characteristics are stable in the antenna operating region. It provides as ECC < 0.01, diversity gain >9.9 dB. The antenna offers low average specific absorption rate (SAR) of 0.169 W/kg. The simulated and measured results are found to be in reasonable match.

The MIMO antenna is proposed for on-body communication, hence, a very thin jean cloth material is used as substrate. This negates the necessity of additional material usage in antenna design and the result range indicates good diversity performance and with a low SAR of 0.169 W/kg for on-body performance. This makes it a suitable candidate for textile antenna application.

The purpose of this paper is to study the effect of surface salt spray duration on the fretting wear and electrochemical corrosion behaviors of Inconel 690 alloy.

A high-temperature steam generator was applied to salt spray test samples, a fretting wear rig was used to realize the damage behavior tests, an electrochemical workstation was applied to analysis the changes of each sample’s corrosion dynamic response before and after fretting wear.

The thickness of the oxide film that formed on sample surface was increased with the salt spray duration, and somewhat it could act as lubrication during the fretting wear process; however, the corrosive chloride would accelerate the fretting mechanical damage behavior.

In a salt steam spray condition, the fretting tribo-corrosion behaviors of Inconel 690 alloy surface was studied.

This study investigates the views of Italian aquaculture production science students, in their role of future operators, on the application of circular economy strategies.

A key step in the development of professional knowledge is to solicit the opinions of the future operators in the aquaculture sector. The authors used the Q methodology to assess the perceptions of the students on four different knowledge dimensions of the CE: operations, culture and organization, products and services, and ecosystem.

Four discourses emerge from the results, representing the respondents' views on the CE. The first discourse considers CE as business strategy applicable to products and services, the second a corporate mission and the fourth an operational efficiency strategy. Finally, the third discourse views CE as a multidimensional concept.

This study contributes to the scientific and institutional debate on how to accelerate the aquaculture's circular transition. First and foremost, it offers insights to guide policy makers in the development of appropriate knowledge and information systems. Second, it offers the opportunity to improve training programmes to enable current students to be prepared for the future challenges.

The results reflect a different perceived knowledge of CE among future operators, whose opinions are little explored in the literature.

This research aims to examine the ways and the extent to which social media platforms undermine the spiral of silence by facilitating the expression of diverse voices and opinions.

Semi-structured interviews were conducted with members of closed groups focused on non-consensus topics.

Facebook closed group members perceive the media as isolating and portraying their issues negatively. However, these groups offer support, inclusion and non-judgmental opinion-sharing space. Consequently, members feel more comfortable discussing and sharing the topic outside the group, indicating a slight trend of challenging and undermining the spiral of silence through social networks.

The study faces challenges in comparing diverse groups due to unique circumstances, complex needs and societal attitudes. Each group stands alone, potentially yielding slightly different findings.

Social media challenges and undermines the spiral of silence, as these opinions are shared with the wider society and can even find their way back to mainstream media outlets. Thus, social media platforms play a significant role in disrupting the spiral of silence and facilitating the expression of diverse opinions that may have been previously suppressed.

This research emphasizes the critical role of social media in shaping public opinion and its interaction with the broader media landscape, illustrating a circular process where social media disrupts the spiral of silence by facilitating the expression of previously suppressed diverse opinions, which can then potentially influence mainstream media.

This study adds value by exploring how social media platforms can challenge and undermine the spiral of silence, enabling the expression of diverse, marginalized and underrepresented opinions in society. It highlights the role of social media in shaping public opinion and discourse, challenging the dominance of traditional media. Its originality emanates from its revelations concerning the legitimization of conversational topics, which may consequently affect media agendas.