Minimal Contribution Research Articles

Genetic Variations on Chromosome 6p21 Are Associated with Asthma Risk and Disease Severity: A Case–Control Study from Pakistan

Background: Genetic factors play a role in asthma severity. However, low- and middle-income countries have minimal contribution to genomic asthma research. The current study investigates the influence of an important genetic asthma region (6p21) on severe asthma in a cohort of asthmatics in Pakistan. Materials and Methods: In this case–control study, mild to severe asthmatic patients (n = 255) and controls (n = 260) were enrolled from Lahore, Pakistan. Blood samples were collected, and genomic DNA was extracted for the genotyping of 11 single nucleotide polymorphisms located in the 6p21 region. Severe asthma was defined based on the defined daily dose of inhaled corticosteroids equivalent to 200 mcg of beclomethasone dipropionate (as per the global initiative for asthma guidelines). An additive genetic model was followed to find the associations between these variants and the outcome. Univariate and multivariate logistic regression, adjusted for confounders, was performed. Odds ratio (OR), 95% confidence interval (95% CI), p-value, and q-values after FDR adjustment were estimated. Results: The genetic variants rs3025028, rs987870, and rs3025039 showed strong associations with the incidence of asthma with odds ratios of 1.58, 1.62, and 2.70 (95% CI = 1.16–2.16, 1.15–2.30, and 1.40–5.39, respectively). Further stratification analysis to study the risk of severe asthma also revealed markedly significant associations for rs3025020 and rs1799964 (OR = 2.28 and 2.99; 95% CI = 1.39–3.86 and 1.75–5.33, respectively). However, the SNPs rs2070600, rs987870, and rs3025039 also showed a significant relationship with the severity (OR = 2.34, 1.75, and 2.72; 95% CI = 1.02–5.97, 1.07–2.98, and 1.11–7.71, respectively), but FDR-adjusted q-values were insignificant (0.10, 0.07, and 0.07, respectively). Conclusions: The 6p21 region variants rs3025028, rs987870, and rs3025039 are associated with the incidence, whereas rs3025020 and rs1799964 are associated with the risk of more severe asthma in the Pakistani population.

A minimally invasive modified revolving-door flap for surgical reconstruction of concha and antihelix defects

Skin cancers affecting the concha and antihelix are quite common, because of anterior auricular projection from the head and subsequent actinic exposure, leading to the need for effective ear reconstruction post-surgery. Various methods such as skin grafts, free tissue transplantation, and local flaps have been used. This study introduces a refined technique for concha-antihelix defect reconstruction, based on a minimally invasive modification of the revolving-door flap procedure. Here, a fasciocutaneous flap technique involving minimal posterior auricular muscle contribution is used, particularly suitable for anterior skin and cartilage defects. The study included 75 patients with nonmelanocytic skin carcinoma on the ear's anterior surface, in which we evaluated patient's and surgeon's satisfaction with a visual analogue scale and discussed the surgical technique and its advantages and indications. The technique demonstrated excellent cosmetic and functional outcomes, effectively hiding donor-site deformities and ensuring patient and surgeon contentment. This approach allows for one-stage reconstruction under local anesthesia, reducing costs, surgery time, and recovery period. The procedure provides high-quality tissue for reconstruction with low complication risks, making it an optimal choice for wide conchal and antihelix defect repairs due to its proximity to the affected area and the reliable, swift nature of the method.

Quick Groundwater Flow to Tropical Savanna Springs (Mataranka, Northern Territory, Australia)

The Mataranka Springs Complex is a regional groundwater discharge for the Cambrian Limestone Aquifer (CLA) of the Northern Territory (Australia) and forms the headwaters for the environmentally sensitive Roper River. Whilst a regional groundwater contribution to the spring flow is well established, the absence of cover over the CLA in the vicinity of the springs and the prevalence of karst suggest that a component of quick flow during the wet season is possible. A quick flow contribution to the springs was evaluated using a biweekly monitoring programme for several environmental tracers (major ions, stable isotopes of water, and 222Rn) at two large springs (Rainbow Spring and Bitter Spring) and at one minor spring (Fig Tree Spring) over a two-year period that included a relatively dry (2019–2020) and a relatively wet (2020–2021) rainy season. There were limited variations in all tracers at Rainbow and Bitter springs throughout the monitoring programme, indicating an absence or a minimal contribution from quick flow. In contrast, all tracers responded to large rainfall events at a scale of days to weeks in Fig Tree Spring, consistent with a component of quick flow. However, the tracer response at Fig Tree was complex and possibly involved a combination of quick flow, unsaturated zone processes, and changes in the geochemical environment in the aquifer. Quick flow may be favoured in the parts of the Mataranka Springs Complex, where flow paths flow through the karstic tufa layer overlying the CLA.

Production of activated biocarbons by microwave-assisted chemical activation of hardwood sawdust and their application in the simultaneous removal of polymers of different origins from aqueous systems

Sawdust from deciduous trees was used as a raw material for the preparation of carbonaceous adsorbents. Microwave-assisted chemical activation with K2CO3 and H3PO4 was used to produce materials with a well-developed porous structure. The obtained activated biocarbons were characterized in terms of their porous structure, elemental composition, morphology, thermal stability, as well as surface and electrokinetic properties. The sorption abilities of both materials towards synthetic (poly(acrylic acid)) and natural (lysozyme) polymers in the process of their removal from aqueous systems were determined. Both single adsorbates and mixed solutions of two polymeric adsorbates were tested. The stability of aqueous suspensions containing activated biocarbons and one or two polymers was also determined. As a result of microwave-assisted chemical activation two carbonaceous adsorbents were obtained, characterized by a very well-developed specific surface area (1093–1777 m2/g), a completely different type of porous structure (mesoporous or microporous), and the acidic nature of the surface. The maximum adsorption of poly(acrylic acid) was obtained from a mixed solution of both polymers and it reached values of 379 mg/g (for the sample activated with H3PO4 with mean pore diameter 3.04 nm and minimal contribution of micropores—0.3%) and 259 mg/g (for K2CO3 activated material characterized by the mean pore diameter equal to 1.72 nm and large contribution of micropores—77.4%). In the case of lysozyme, the adsorption efficiency was two times lower (sorption capacity of 127–166 mg/g). Based on the collective data analysis, it can be stated that the most probable mechanisms of polymeric destabilization (highly desirable in separation from the multicomponent solutions) are surface charge neutralization at pH 3 and bridging flocculation at pH 11 (especially for the systems containing material activated with H3PO4 and poly(acrylic acid)).

Abstract 4137717: Atrial Fibrillation in Valvular Heart Disease: Assessing the Impact of Genetics in the UK Biobank

Background: Atrial fibrillation (AF) in valvular heart disease (VHD) is typically linked to pressure or volume overload resulting in atrial remodeling. However, the independent contribution of genetics to AF in VHD beyond abnormal hemodynamics and other risk factors remains unclear. Objective: To study the role of a previously developed Polygenic Risk Score (PRS) for AF in predicting AF across different VHDs in the UK Biobank cohort. Methods: We analyzed UK Biobank data between 2000 and 2022. ICD codes were used to define incident AF and VHD status, including mitral valve (MV) disease [prolapse (MVP), regurgitation (MR) and stenosis (MS)] and aortic (AV) disease [stenosis (AS) and regurgitation (AR)]. Prior AF was excluded. Participants were divided into quintiles based on the PRS: the top quintile was defined as high genetic AF risk, second through fourth as intermediate genetic risk, and bottom quintile as low genetic risk. Results: Among 452841 participants with available PRS, 2238 had at least one VHD (385 MVP, 1058 MR, 81 MS, 421 AR, and 509 AS). AF incidence was 9.9%, 13.6%, and 19% in the low, intermediate and high genetic risk groups respectively, compared to 1.4%, 2.8%, and 5.7% in the general population (all p<0.05) - Figure 1A . Cox regression models adjusted for cardiovascular risk factors showed different genetic effects on AF across VHD types. Censoring patients at death, including valve intervention as a time-dependent variable, and excluding AF within 30 days post-intervention, PRS independently predicted AF in MV disease (hazard ratio [HR] 1.7, p=0.03 for the intermediate risk/mid PRS; HR 2.3, p=0.002 for the high risk PRS), particularly in those with MVP (HR 3.1, p=0.03 for the high PRS). However, in those with AV disease, PRS was not significantly associated with AF (p=0.93 and p=0.07) - Figure 1B. Conclusion: In patients with VHD, AF PRS is significantly associated with an increased risk of developing AF. However, the genetic impact varies across different VHD. In AV disease, there is a minimal genetic contribution, and the elevated AF risk may be predominantly due to pressure or volume overload. In contrast, in MV disease, particularly in MVP, there is a substantial genetic influence on AF risk.

Assessment of the free shear boundary condition in a capillary meniscus via molecular dynamics

Computational fluid dynamics models often employ the free shear boundary condition at free surfaces, a result from the continuity of the stress and the large viscosity contrast at liquid–gas interfaces. This study leverages nonequilibrium molecular dynamics simulations to investigate the validity of the free shear boundary condition on the exposed surface of a liquid meniscus at the nanoscale. The primary objective is elucidating the fundamental mechanisms and behavior of fluid interactions within a capillary meniscus formed between two carbon nanotubes (CNTs) in shear-driven flow. Shear-driven flow simulations were conducted by varying the velocity of a solid slab to induce different shear rates in the adjacent water molecules. The results demonstrate, for the first time, negligible shear at the free surface, supporting the free shear assumption from the nanoscale point of view. A force balance analysis reveals that capillary and surface tension forces dominate within the meniscus, dictating its shape and stability. Meniscus deformation was observed and primarily attributed to interatomic interactions between water molecules and CNTs, driven by a combination of short-range repulsive forces and van der Waals attractions. The minimal contribution from shear forces suggests that interatomic forces, rather than applied shear stress, are the primary drivers of the meniscus deformation. These findings offer valuable insights into fluid behavior and a sound fundamental analysis of the free shear boundary condition at the nanoscale.

How does a soft collision orogen uplift and collapse? Insight from the eastern Central Asian Orogenic Belt

The mechanism of uplift and collapse is critical for understanding orogenic evolution within the Wilson cycle. The Central Asian Orogenic Belt (CAOB) represents one of the largest Phanerozoic accretionary orogens on Earth, experiencing terminal soft collision following the closure of the Paleo-Asian Ocean. However, the timing and mechanism of crustal thickening and thinning in the eastern CAOB remain unclear. Here, we present geochronological, mineralogical, geochemical, and Sr-Nd-Hf isotopic data of the newly identified Late Triassic bimodal dike associations in the easternmost CAOB. The ca. 236−230 Ma mafic dikes can be divided into two groups based on petrographic and geochemical characteristics. Major element modeling using the MELTS software indicates that they evolved via independent differentiation paths. Trace element and isotope simulations reveal that the ca. 236−230 Ma mafic dikes originated from the 4%−10% partial melting of spinel- to garnet-lherzolite lithospheric mantle sources over a range of depths, with varying inputs of asthenospheric mantle materials. Coeval ca. 233 Ma felsic dikes exhibit adakitic geochemical characteristics and strong imprints of crust-mantle interaction, suggesting derivation from melting of a heated juvenile mafic lower crust as a result of the upwelling of asthenospheric mantle. The formation of bimodal dike associations records the transition from lithospheric mantle thinning to delamination. Integrating a large dataset and employing multiple geochemical proxies, our results reveal that the crust of the easternmost CAOB reached a thickness of 54 ± 3 km at ca. 280−255 Ma, likely resulting from magmatic underplating due to rollback of the subducting Paleo-Asian Oceanic slab. This region underwent a further slight increase in crustal thickness to 61 ± 2 km at ca. 254−237 Ma in response to limited tectonic shortening associated with soft collision orogeny before it thinned to 45 ± 13 km at ca. 236−210 Ma due to lithospheric delamination during post-collisional extension. Our findings reveal that the uplift of the eastern CAOB was primarily driven by magmatic underplating, with minimal contribution from tectonic shortening. Lithospheric delamination emerged as an important factor leading to the eventual collapse of the eastern CAOB. Compared to typical hard collisional orogens (e.g., the Himalaya-Tibet orogen), the CAOB experienced significantly weaker tectonic shortening followed by similar lithospheric delamination during post-collisional extension. This study highlights the importance of integrating geochemical and isotopic data in quantifying the complex evolutionary histories of ancient collisional orogenic belts.

Analisis model kebijakan program penyaluran “KUR” dalam rangka meningkatkan perilaku kepatuhan wajib pajak pelaku “UMKM”

The Micro, Small, and Medium Enterprises (MSMEs) sector has long been a significant driver of Indonesia's economy, drawing considerable attention from the government. According to the National Medium-Term Development Plan (RPJMN), various strategic measures have been implemented to promote the growth and resilience of MSMEs as a means to enhance national economic independence. However, despite their substantial economic contribution, MSMEs' tax compliance remains low, as reflected in their minimal contribution to tax revenue. The small contribution is an indication that the level of compliance of MSMEs actors in fulfilling their tax obligations is still very low. This research was conducted using a qualitative approach and began by analyzing and evaluating the policy of the People's Business Credit (KUR) distribution program in relation to tax aspects. The analysis and evaluation were based on data sourced from literature studies and interviews with relevant resource persons from the point of view of technical feasibility, economic and financial possibility, political viability, and administrative operability. The results show that the existing policy has not fully accommodated taxation aspects. This is unfortunate considering that the KUR interest subsidy provided by the government to MSMEs actors is financed by the State Budget (APBN), which is mostly sourced from taxes. Furthermore, the study proposes policy model to encourage the development of the MSMEs actors.

FINANCIAL RESOURCES OF SMALL AND MEDIUM ENTERPRISES

As of right now, Hanoi has achieved significant progress in terms of administration, leadership, direction, and setting up the right environment for SMEs to grow. The percentage of SMEs that enter the production and business activities with income in the year is low compared to the total, and they continue to make a minimal contribution to overall economic growth. SMEs' production and business results are not good in the city. This article researches, analyzes, and measures the financial resources of SMEs in Hanoi and, on that basis, proposes solutions to improve the financial resources of SMEs in Hanoi. Survey data was collected from 300 workers working at SMEs in Hanoi, but only 240 questionnaires met the requirements for analysis. Through qualitative research methods combined with quantitative research methods, research results show that the financial resources of SMEs are highly appreciated. No appreciable variation exists between the financial resources of SMEs in Hanoi between these different professional seniorities and job positions. This is the basis for proposed solutions to increase the financial resources of SMEs in Hanoi.

Flexural behaviour of BFRP grid/bar reinforced UHPC beams and slabs

This study investigates the integration of Basalt Fiber Reinforced Polymer (BFRP) and Ultra-High Performance Concrete (UHPC), which exhibit significant potential for a durable and sustainable solution in marine and offshore infrastructure. An experimental program of BFRP grid/bar-reinforced UHPC beams and slabs subjected to four-point bending is presented. A total of nine beams and ten slabs were prepared and tested to investigate the effect of BFRP reinforcement ratio (0 %–3.33 %), type of reinforcement (grid and bar), and steel fiber content of UHPC (0 %, 1 %, 2 % and 3 %). The results revealed that the inclusion of BFRP reinforcement, even at a small reinforcement ratio, is feasible to enhance structural ductility due to the large rupture strain and superior strength characteristics of BFRP material. Moreover, the steel fibers played a crucial role in preventing shear failures of UHPC and creep failures of BFRP reinforcement. Within a range of 0–2 %, the steel fiber content not only benefited the load-resistance and deformation capacity but also effectively improved the cracking load. However, high fiber content (3 %) had a minimal contribution to load-bearing capacity and negatively affected ductility. A theoretical model based on the deflection method was employed to forecast the general behaviour of the flexural members. Comparisons between experimental results and numerical predictions confirm its accuracy.

Biochar captures ammonium and nitrate in easily extractable and strongly retained form without stimulating greenhouse gas emissions during composting.

During composting of organic waste, nitrogen is lost through gaseous forms and ion leaching. Biochar has been shown to capture mineral nitrogen (Nmin: NH4 + and NO3 -) from compost, which we hypothesize reduces N2O formation. However, associating Nmin captured by biochar with the dynamics of N2O and other greenhouse gas (GHG) emissions during composting remains unstudied and was the aim of this work. We composted (outdoor for 148 days) together kitchen scraps (43.3% dw, where dw is dry weight), horse manure (40.9% dw), and wheat (Triticum aestivum L) straw (15.8% dw) without (Control) or with biochar (Bc, 15% compost dw). The biochar consisted of hardwood and softwood pieces pyrolyzed at 680°C and exhibited 60% of particles with 4-8mm. We monitored compost GHG (CO2, CH4, N2O) emissions, Nmin content in compost and biochar particles (sequential extractions), and biochar surface transformations (SEM-EDX and 13C-NMR spectroscopy) along composting. Biochar did not significantly reduce or increase GHG emissions and Nmin content (mg kg-1) in compost. However, the final NO3 - amount (g compost pile-1) in the Bc treatment was significantly higher (54%) compared to the Control, indicating lower NO3 - losses. Despite the high aromaticity and minimal contribution of carboxyl C to the biochar structure, biochar retained NH4 +, mainly in easily extractable form (55%), in the first 2 weeks of composting and mainly in strongly retained form (75%) in the final compost. The NO3 - content in biochar increased continuously during composting. In the final compost, the NO3 - content extracted from biochar was 164 (37%, easily extractable), 80 (19%, moderately extractable), and 194mg NO3 --N kg-1 (44%, strongly retained). Although Nmin retention in biochar was not accompanied by lower N2O emissions, contradicting our hypothesis, we demonstrated the efficacy of biochar to recover Nmin from organic waste without stimulating GHG emissions.

Closing the gap: examining the impact of source habitat proximity on plant and soil microbial communities in post-mining spoil heap succession.

Revegetation of barren substrates is often determined by the composition and distance of the nearest plant community, serving as a source of colonizing propagules. Whether such dispersal effect can be observed during the development of soil microbial communities, is not clear. In this study, we aimed to elucidate which factors structure plant and soil bacterial and fungal communities during primary succession on a limestone quarry spoil heap, focusing on the effect of distance to the adjoining xerophilous grassland. We established a grid of 35 plots covering three successional stages - initial barren substrate, early successional community and late successional grassland ecosystem, the latter serving as the primary source of soil colonization. On these plots, we performed vegetation surveys of plant community composition and collected soil cores to analyze soil chemical properties and bacterial and fungal community composition. The composition of early successional plant community was significantly affected by the proximity of the source late successional community, however, the effect weakened when the distance exceeded 20 m. Early successional microbial communities were structured mainly by the local plant community composition and soil chemical properties, with minimal contribution of the source community proximity. These results show that on small spatial scales, species migration is an important determinant of plant community composition during primary succession while the establishment of soil microbial communities is not limited by dispersal and is primarily driven by local biotic and abiotic conditions.

Resampling approach for imbalanced data classification based on class instance density per feature value intervals

In practical applications, imbalanced datasets significantly degrade the classification performance of machine learning models. However, most conventional resampling approaches fall short in adequately addressing the varying contributions of individual features to the classification model. In response to this defect, this study introduces three novel resampling approaches. The first approach, Oversampling based on class instance density per feature value intervals (OCF), focuses on augmenting the dataset. The second approach, Undersampling based on class instance density per feature value intervals (UCF), seeks to reduce dataset size. The third approach, Hybrid sampling based on class instance density per feature value intervals (HSCF), which can perform oversampling and undersampling simultaneously. These approaches categorize feature value into different intervals based on their varying information content, calculate class instance densities within these intervals, and generate feature values in intervals with high discriminative information. Subsequently, these generated features are combined to synthesize minority class data, effectively achieving oversampling. Additionally, the study combines class instance density and feature importance to identify majority class data at the classification boundary with minimal contribution and subsequently executes undersampling. The flexibility to adjust sampling ratios and the integration of OCF and UCF enable the implementation of hybrid sampling. Finally, experiments on the benchmark dataset demonstrate the superiority and effectiveness of the proposed method. Furthermore, it is observed that the method proposed in this study enhances the feature dividing capability of decision tree classifiers. Hence, the best results are achieved when working in synergy with decision tree classifiers, leading to the most significant improvements in classification performance. All codes have been published at https://github.com/Wangfeiopen/HSCF.

Time-Dependent Evolution of Al-Al4C3 Composite Microstructure and Hardness during the Sintering Process.

In this study, Al-Al4C3 compounds were manufactured by mechanical milling followed by heat treatment. To analyze the microstructural evolution, the composites were sintered at 550 °C at different sintering times of 2, 4 and 6 h. The mechanical results suggest that dislocation density and crystallite size primarily contribute to hardening before the sintering process, with a minimal contribution from particle dispersion in this condition. The compound exhibited a significant 75% increase in hardness after 2 h of sintering, primarily attributed to the nucleation and growth of Al4C3 nanorods. The HRTEM analysis, combined with geometric phase analysis (GPA) at and near the Al-Al4C3 interface of the nanorods, revealed strain field distributions primarily associated with partial screw dislocations and the presence of closely spaced dislocation dipoles. These findings are consistent with the microstructural parameters determined from X-ray diffraction pattern analysis using the convolutional multiple whole profile (CMWP) method. This analysis showed that the predominant dislocation character is primarily of the screw type, with the dislocation dipoles being closely correlated. Based on these results, it is suggested that samples with a lower weight percentage of reinforcement and longer sintering times may experience reduced brittleness in Al/Al4C3 composites. Strengthening contributions were calculated using the Langford-Cohen and Taylor equations.

Leadership matters: The role of destructive leadership behavior and teachers’ demographic characteristics on teachers’ social engagement with students

The study intended to investigate the role of destructive leadership behavior, and teachers’ demographic characteristics on teachers’ social engagement with students in colleges of teacher education in the State of Amhara. A mixed method with an explanatory sequential design was employed. 397 teachers and 366 students participated in the quantitative data collection (questionnaire), whereas the qualitative data were collected with the help of interviews with college deans and teachers. Data collected through a questionnaire was analyzed through descriptive and inferential statistics. On the other hand, narration and interpretation were employed for qualitative data analysis. Findings revealed that deans’ destructive leadership behavior was exhibited significantly. Teachers were socially engaged with students (t (396) = 58.902, d = 0.54, p = .000). Deans’ destructive leadership behavior and demographic characteristics explain teachers’ social engagement with students. However, demographic characteristics only have a minimal contribution in explaining teachers’ social engagement with students. In conclusion, demographic characteristics have no role in teachers’ social engagement with students but destructive leadership behavior plays a role. Finally, recommendations were forwarded to potential stakeholders.

The AUREX cell: a versatile operando electrochemical cell for studying catalytic materials using X-ray diffraction, total scattering and X-ray absorption spectroscopy under working conditions.

Understanding the structure-property relationship in electrocatalysts under working conditions is crucial for the rational design of novel and improved catalytic materials. This paper presents the Aarhus University reactor for electrochemical studies using X-rays (AUREX) operando electrocatalytic flow cell, designed as an easy-to-use versatile setup with a minimal background contribution and a uniform flow field to limit concentration polarization and handle gas formation. The cell has been employed to measure operando total scattering, diffraction and absorption spectroscopy as well as simultaneous combinations thereof on a commercial silver electrocatalyst for proof of concept. This combination of operando techniques allows for monitoring of the short-, medium- and long-range structure under working conditions, including an applied potential, liquid electrolyte and local reaction environment. The structural transformations of the Ag electrocatalyst are monitored with non-negative matrix factorization, linear combination analysis, the Pearson correlation coefficient matrix, and refinements in both real and reciprocal space. Upon application of an oxidative potential in an Ar-saturated aqueous 0.1 M KHCO3/K2CO3 electrolyte, the face-centered cubic (f.c.c.) Ag gradually transforms first to a trigonal Ag2CO3 phase, followed by the formation of a monoclinic Ag2CO3 phase. A reducing potential immediately reverts the structure to the Ag (f.c.c.) phase. Following the electrochemical-reaction-induced phase transitions is of fundamental interest and necessary for understanding and improving the stability of electrocatalysts, and the operando cell proves a versatile setup for probing this. In addition, it is demonstrated that, when studying electrochemical reactions, a high energy or short exposure time is needed to circumvent beam-induced effects.

Leading the Transition from Halogen Refrigerants to Natural Refrigerants in Indonesia (Pertamina Plaju Refinery as a Pioneer)

Abstract Climate change has become a worldwide concern, prompting Indonesia to take ambitious actions to reduce emissions and control rising temperatures. The rapid growth of the Refrigeration and Air Conditioning (RAC) industry in Indonesia has led to higher greenhouse gas emissions. To tackle these environmental challenges, Pertamina Plaju Refinery is manufacturing natural refrigerants, specifically Musicool (Propane) and Breezone (Propylene), providing sustainable replacements for R-22 and R-32. Pertamina Plaju Refinery has made several process modifications and optimizations to support the production of Musicool and Breezone in the Alkylation and Purification Units. These modifications involve optimizing operating conditions and implementing necessary infrastructure changes. In general, Pertamina’s natural refrigerants consume 20-30% less energy than halogen refrigerants while offering similar cooling capacity to R-22 and R-32. Propane and Propylene-based refrigerants have the lowest impact on global warming and are eco-friendly due to their easy degradation process. Musicool and Breezone, having an ODP of 0.0, with maximum GWP of 3.3, indicating minimal contribution to ozone depletion. Pertamina’s efforts to engage and reach potential customers on these natural refrigerants, involve collaborative efforts among various organizations, including with all District Office Plaju, South Sumatra.

GRAPHENE AS AN ANTIOXIDANT AND ANTIOZONANT IN TIRE SIDEWALL COMPOUNDS

ABSTRACT Tire sidewalls have an important function in achieving optimized tire performance. The sidewall compound must show good abrasion resistance, aging resistance, and tear strength; low hysteresis and minimal contribution to whole tire rolling resistance; and good adhesion to adjacent components in the tire. In addition, in both the original equipment market and the premium performance market, appearance is of considerable importance. The current system of waxes, antioxidants, and phenyl diamine antiozonants is very effective in meeting the need of the tire end user. However, recent concerns centered on the environmental impact of N′-phenyl-p-phenylenediamine, specifically N-(1,3-dimetylbutyl)-N′-phenyl-p-phenylenediamine, and staining and discoloration of the tire sidewall surface raise issues that should be addressed. Specialized grades of graphene can offer a mechanism by which tire appearance and environmental concerns can be overcome. Pristine graphene can improve compound resistance of ozonolysis and oxidation by replacing the current antiozonants and antioxidants used in tire compounds; improve tire sidewall appearance; and improve tire sidewall resistance to scuffing, abrasion, and tearing.

Near-surface ocean temperature and air-sea heat flux observed by a buoy array during summer to autumn in year 2014 in the northern South China Sea

The observational data of the air-sea interface and upper ocean elements from a buoy array deployed in the northern South China Sea from June to November 2014 is analyzed. The COARE 3.0 algorithm was adopted to examine the variability of air-sea heat fluxes and their contributions to near-surface ocean temperature changes. During the observation period, air-sea heat exchange in the northern South China Sea is primarily determined by solar shortwave radiation and latent heat flux, with net heat flux mostly negative, indicating that the ocean predominantly loses heat. In autumn, net heat flux loss significantly increased by an average of 34.4 W/m2, primarily due to enhanced latent heat loss driven by stronger winter monsoon. During typhoon period, net air-sea heat flux was significantly suppressed, mainly due to reduced solar shortwave radiation, with minimal contribution from sensible heat flux. Near-surface ocean temperature exhibited a seasonal cooling trend, averaging 29.7°C in summer and 28.4°C in autumn. The maximum cooling during typhoon reached 3.1°C, with minimal contribution from air-sea heat flux. During the monsoon transition period, weaker winds led to a slight increase in near-surface ocean temperature, with air-sea heat flux contributing 70.2% and 56.3% to this process. During winter monsoon, more uniform water column mixing resulted in a gradual decrease in near-surface ocean temperature, with air-sea heat flux contributing over 60% to this process.

An Analysis of the Patterns of Economic Growth in the US

ABSTRACT This article seeks to investigate which demand component led and shaped the growth patterns of the US economy between 1954 and 2020 and comprehensive sub-periods relying on a proper allocation of imports. In doing so, it aims to establish whether the external sector can make a positive contribution to growth even in a context of negative net exports. Finally, it seeks to shed light on the reasons for higher or lower output growth, drawing particular attention to the engines of growth in each historical period. This article takes a novel approach in two ways: (1) it calculates and analyzes the decomposition of the contributions to growth for the US; (2) it divides the analysis into sub-periods and engines of growth, separately analyzing movements in the components of the multiplier, the dynamics of each component’s share with respect to GDP, and their respective growth rates. The empirical results show that the very low growth rates experienced between 2008 and 2020 are mainly explained by a minimal contribution of the government sector accompanied by weak demand from the private sector, highlighting the importance of growth-oriented public policies. These negative results have been only partially compensated by improvements in the external sector.