Conventional all-air cooling systems struggle with high latent loads and increased energy demand in tropical buildings, where humidity and solar radiation intensify the design challenge. This study systematically reviews radiant cooling system (RCS) research in tropical and hot, humid climates, synthesizing evidence from 152 peerreviewed studies published between 2013 and 2025. The review is structured around four dimensions: operating principles and system types, energy efficiency, thermal comfort, and advanced control strategies. Key quantitative findings include: properly designed RCSs reduce energy consumption by 4-43% relative to conventional air systems, with peak savings of up to 56% when integrated with phase change materials or geothermal heat pumps; RCSs maintain comfort at air temperatures 1-2 K higher than traditional systems, with a predicted mean vote within the acceptable range (-0.5 to +0.5) for over 81% of occupied hours; model predictive control maintains EN 15251 Category II standards for more than 95% of occupied hours while reducing cooling-tower energy use by up to 55%, with membrane-assisted sub-dew-point panels reducing annual discomfort hours by 3-6% versus conventional RCS. The primary contribution is a structured, evidence-based framework that: (1) taxonomizes hybrid RCS configurations by tropical microclimate severity; (2) synthesizes condensation-risk thresholds and control design criteria; and (3) delineates a technology-readiness roadmap for net-zero buildings in humid environments. Research gaps include the absence of in situ validation of membrane-assisted RCS in operational tropical buildings, the lack of standardized condensation-risk thresholds, and the need for machine learning controllers validated across diverse tropical microclimates.
This work presents a passively Q-switched erbium-ytterbium codoped fiber laser (EYDFL) using a linear cavity design and SiO2 fabricated from rice husk ash (RHA) saturable absorber (SA). The SA exhibited a high modulation depth of 20.7% and a saturation intensity of 1.07 MW cm-2. At lower pump powers, the laser emitted continuous-wave at 1557 nm and 1567 nm. This phenomenon arises because the reflection spectrum of the fiber Bragg grating (FBG) and the Faraday mirror supports lasing at two distinct wavelengths. The dual-wavelength feature arises from the interplay between wavelength-selective FBG reflection and cavity-induced interference within the linear cavity. Although dual-wavelength operation can be mitigated by incorporating a subring cavity to enhance mode selectivity, the primary objective of this study is to investigate and demonstrate laser performance in a simple linear-cavity configuration without additional cavity modifications. Upon increasing the pump power beyond 1.08 W, stable Q-switched pulses at 1567 nm emerged. The system achieved a pulse duration of 4.81 & micro;s, a repetition rate of 12.3 kHz, and a signal-to-noise ratio of 33 dB. As the pump power increases from 1.08 W to 1.6 W, the pulse duration decreases from 6.51 & micro;s to 4.81 & micro;s, indicating that Q-switched pulses become narrower at higher pump powers. In contrast, the repetition rate rises from 6.7 kHz to 12.3 kHz with increasing pump power. Hence, increasing the pump power leads to shorter pulse durations and higher repetition rates, demonstrating more efficient Q-switched pulse generation. This compact single linear-cavity EYDFL highlights the potential of RHA-derived SiO2 as a sustainable SA.
Objectives: This study investigates morphological and ultrastructural changes in skeletal muscles of diabetic rats induced by streptozotocin (STZ) using light microscopy, field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). Together, these imaging methods allow for detailed visualization of tissue-level and subcellular changes in the gastrocnemius muscle, offering an integrated view of diabetes-related pathology. Materials and Methods: Diabetes was induced in male Sprague-Dawley rats through a single intra-peritoneal injection of STZ (at 65 mg/kg). After 30 days of diabetes maintenance, the rats were euthanized, and gastrocnemius muscle samples were harvested for Hematoxylin and Eosin (H&E), Masson's Trichrome (MT), and histochemical staining. Morphological features were examined using FESEM, and ultrastructural organization was analyzed using TEM. Results: Our findings confirm that hyperglycemia severely damages skeletal muscle in STZ-induced diabetic rats, characterized by extensive myofiber injury, atrophy, and mitochondrial disruptions. Ultrastructural analysis revealed extensive architectural disruptions and clear deviations from normal morphology. Conclusions: Our study provides evidence of profound structural and cellular alterations in diabetic skeletal muscles and offers insights for developing strategies to mitigate pathological changes, preserve muscle integrity, and support functional recovery.
Diabetes mellitus is a major chronic metabolic disorder that often leads to serious long-term vascular complications. Traditional monitoring methods focus mainly on metabolic indicators and often miss early vascular changes. This study developed and validated a non-invasive framework for classifying diabetic status based on photoplethysmogram (PPG) pulse morphology. The approach offers a scalable and affordable alternative to invasive blood tests. A dataset from 78 Malaysian participants was analyzed in five phases: signal pre-processing, feature extraction, and statistical ranking. Raw signals were filtered with a 4th-order Chebyshev Type II band-pass filter for accurate waveform analysis. From a wide set of temporal and amplitude features, key biomarkers linked to arterial stiffness and vascular compliance were identified and ranked. Six supervised machine learning models were evaluated: Logistic Regression, Decision Tree (DT), KNN, Support Vector Machine (SVM), Artificial Neural Network (ANN), and Na & iuml;ve Bayes (NB). ANN and SVM models achieved the highest classification accuracy and AUC. This demonstrates effective distinction between diabetic and non-diabetic status using interpretable waveform features. Validation with a Southeast Asian cohort addresses a demographic gap in the literature. The framework shows that ranked PPG biomarkers can be used for accessible, community-level diabetes screening, especially in healthcare settings with limited resources.
Background: Micro-, small-, and medium-sized herbal enterprises (MSMHEs) play a crucial role in Indonesia's economy, particularly in East Java. As digital technologies reshape market dynamics, enterprises face pressure to adopt digital marketing strategies. However, the unique challenges and opportunities encountered in this digital transformation process remain understudied. Objective: This study aimed to explore the challenges and opportunities in implementing digital marketing strategies among MSMHEs in East Java, focusing on the perspectives of owners and managers across different enterprise scales. Methods: A qualitative approach was employed involving in-depth interviews with 17 participants from MSMHEs across seven cities in East Java. Participants included owners, technical managers, and those with dual roles. The data were analyzed using thematic analysis to identify the key themes and subcategories. Results: The study revealed varying levels of digital marketing adoption across enterprise scales. Key challenges include limited digital literacy, lack of financial resources, and inadequate infrastructure. Opportunities were identified in the form of a strong desire for training and a curiosity about digital marketing strategies. The perceived necessity of digital transformation varied among the participants and was associated with age, education level, and personal exposure to digital technologies. Conclusion: The findings highlight the need for tailored support mechanisms to address the diverse challenges faced by MSMHEs during their digital transformation journey. This study provides a foundation for developing targeted interventions and policies to support the digital growth of the herbal MSMHE sector in East Java, thereby contributing to the broader economic development of the region.
