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Fulltext The effects of music and auditory stimulation on autonomic arousal, cognition and attention: A systematic review

Chee ZJ, Chang CYM, Cheong JY, Malek FHBA, Hussain S, de Vries M, et al.

Int J Psychophysiol, 2024 May;199:112328.
PMID: 38458383 DOI: 10.1016/j.ijpsycho.2024.112328

According to the arousal-mood hypothesis, changes in arousal and mood when exposed to auditory stimulation underlie the detrimental effects or improvements in cognitive performance. Findings supporting or against this hypothesis are, however, often based on subjective ratings of arousal rather than autonomic/physiological indices of arousal. To assess the arousal-mood hypothesis, we carried out a systematic review of the literature on 31 studies investigating cardiac, electrodermal, and pupillometry measures when exposed to different types of auditory stimulation (music, ambient noise, white noise, and binaural beats) in relation to cognitive performance. Our review suggests that the effects of music, noise, or binaural beats on cardiac, electrodermal, and pupillometry measures in relation to cognitive performance are either mixed or insufficient to draw conclusions. Importantly, the evidence for or against the arousal-mood hypothesis is at best indirect because autonomic arousal and cognitive performance are often considered separately. Future research is needed to directly evaluate the effects of auditory stimulation on autonomic arousal and cognitive performance holistically.

Matched MeSH terms: Attention
Development of audio-guided deep breathing and auditory Go/No-Go task on evaluating its impact on the wellness of young adults: a pilot study

Kwa EK, Cheong SK, Ong LK, Lee PF

Biomed Tech (Berl), 2024 Apr 25;69(2):141-150.
PMID: 37856824 DOI: 10.1515/bmt-2023-0410

OBJECTIVES: Numerous studies indicate that deep breathing (DB) enhances wellbeing. Multiple deep breathing methods exist, but few employ audio to reach similar results. This study developed audio-guided DB and evaluated its immediate impacts on healthy population via self-created auditory Go/No-Go task, tidal volume changes, and psychological measures.
METHODS: Audio-guided DB with natural sounds to guide the DB was developed. Meanwhile, audio-based Go/No-Go paradigm with Arduino was built to measure the attention level. Thirty-two healthy young adults (n=32) were recruited. Psychological questionnaires (Rosenberg's Self-Esteem Scale (RSES), Cognitive and Affective Mindfulness Scale-Revised (CAMS-R), Perceived Stress Scale (PSS)), objective measurements with tidal volume and attention level with auditory Go/No-Go task were conducted before and after 5 min of DB.
RESULTS: Results showed a significant increment in tidal volume and task reaction time from baseline (p=0.003 and p=0.033, respectively). Significant correlations were acquired between (1) task accuracy with commission error (r=-0.905), (2) CAMS-R with task accuracy (r=-0.425), commission error (r=0.53), omission error (r=0.395) and PSS (r=-0.477), and (3) RSES with task reaction time (r=-0.47), task accuracy (r=-0.362), PSS (r=-0.552) and CAMS-R (r=0.591).
CONCLUSIONS: This pilot study suggests a link between it and young adults' wellbeing and proposes auditory Go/No-Go task for assessing attention across various groups while maintaining physical and mental wellness.

Matched MeSH terms: Attention*
The rising tsunami of poor muscle health and sarcopenia in Asia-Pacific: Time for focused attention and targeted interventions

Chew STH, Nguyen HTT, Joshi S, Kamaruzzaman SB, Landi F, Manuel MV, et al.

Arch Gerontol Geriatr, 2024 Feb;117:105275.
PMID: 37988852 DOI: 10.1016/j.archger.2023.105275
Matched MeSH terms: Attention
Time sharing in working memory processing

Barrouillet P, Camos V, Minamoto T, Nishiyama S, Chooi WT, Morita A, et al.

J Exp Psychol Learn Mem Cogn, 2023 Oct;49(10):1539-1556.
PMID: 37307321 DOI: 10.1037/xlm0001261

Although working memory (WM) is usually defined as a cognitive system coordinating processing and storage in the short term, in most WM models, memory aspects have been developed more fully than processing systems, and many studies of WM tasks have tended to focus on memory performance. The present study investigated WM functioning without focusing exclusively on short-term memory performance by presenting participants with an n-back task on letters, n varying from 0 to 2, each letter being followed by a tone discrimination task involving from one to three tones. Predictions regarding the reciprocal effects of these tasks on each other were motivated by the time-based resource-sharing (TBRS) theoretical framework for WM that assumes the temporal sharing of attention between processing and memory. Although, as predicted, increasing the n value had a detrimental effect on tone discrimination in terms of accuracy and response times, and increasing the number of tones disrupted speed and accuracy on n-back performance, the overall pattern of results did not perfectly fit the TBRS predictions. Nonetheless, the main alternative models of WM do not seem to offer a complete account. The present findings point toward the need to use a larger range of tasks and situations in designing and testing models of WM. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Matched MeSH terms: Attention/physiology
Fulltext What Simon "knows" about cultural differences: The influence of cultural orientation and traffic directionality on spatial compatibility effects

Baess P, Ecker UKH, Janssen SMJ, Jin Z, Bermeitinger C

Mem Cognit, 2023 Apr;51(3):526-542.
PMID: 36180770 DOI: 10.3758/s13421-022-01360-9

Previous research has suggested that culture influences perception and attention. These studies have typically involved comparisons of Westerners with East Asians, motivated by assumed differences in the cultures' self-concept or position on the individualism-collectivism spectrum. However, other potentially important sources of cultural variance have been neglected, such as differences in traffic directionality shaped by the urban spatial environment (i.e., left-hand vs. right-hand traffic). Thus, existing research may potentially place too much emphasis on self-concepts or the individualism-collectivism dimension in explaining observed cultural differences in cognition. The present study investigated spatial cognition using a Simon task and tested participants from four nations (Australia, China, Germany, and Malaysia) that differ in both cultural orientation (collectivistic vs. individualistic) and traffic directionality (left-hand vs. right-hand traffic). The task used two possible reference frames underlying the Simon effect: a body-centered one based on global stimulus position relative to the screen's center versus an object-centered one based on local stimulus position relative to a context object. As expected, all groups showed a reliable Simon effect for both spatial reference frames. However, the global Simon effect was larger in participants from countries with left-hand traffic. In contrast, the local Simon effect was modulated by differences in cultural orientation, with larger effects in participants from collectivistic cultures. This pattern suggests that both sources of cultural variation, viz. cultural orientation and traffic directionality, contribute to differences in spatial cognition in distinct ways.

Matched MeSH terms: Attention*
The effects of search-irrelevant working memory content on visual search

Calleja MO, Willoughby AR

Atten Percept Psychophys, 2023 Feb;85(2):293-300.
PMID: 36596986 DOI: 10.3758/s13414-022-02634-9

Previous experiments investigating visual search have shown that distractors that are semantically related to a search target can capture attention and slow the search process. In two experiments, we examine if distractors exactly matching, or semantically related to, search-irrelevant information held in working memory (WM) can also influence visual search while ruling out potential effects of color similarity. Participants first viewed and memorized an image of an everyday object, then they determined if a target item was present or absent in a two-object search array. On exact-match trials, the memorized object appeared as a distractor; on semantic-match trials, an object semantically related to the memorized object appeared as a distractor. Both exact-match and semantic-match distractors slowed search when the target was present in the search array. Our findings extend previous findings by demonstrating WM-driven attentional guidance by complex objects rather than simple features. The results also suggest that visual search can be influenced by distractors sharing only semantic features with a search-irrelevant, but active, WM representation.

Matched MeSH terms: Attention*
Fulltext Harnessing the Challenges and Solutions to Improve Security Warnings: A Review

Zaaba ZF, Lim Xin Yi C, Amran A, Omar MA

Sensors (Basel), 2021 Nov 03;21(21).
PMID: 34770621 DOI: 10.3390/s21217313

The security warning is a representation of communication that is used to warn and to inform a person whether security menaces have been discovered in order to prevent any consequences of damage from taking place. The purpose of a security warning is to provide a legitimate alert (to notify and to warn) to the users so that a secure manner of action is safely conducted. It is worth noting that the majority of computer users prefer to dismiss security warnings due to lack of attention, the use of technical words, and the deficiency of information provided. This paper determines to achieve two outcomes: firstly, a thorough review of problems, challenges, and approaches to improving security warnings. Our work complements the previous classifications in the identification of problems and challenges in security warnings by value-adding a new classification, namely immersion in the primary task. Then, we add other related works within the known classifications accordingly. In addition, our work also presents the classifications of approaches to improving security warnings. Secondly, we propose two timelines by addressing the problems, challenges, and approaches to improving security warnings. It is expected that the outcomes of this research will be useful to researchers within the niche area for analysing trends and providing the groundwork in security warning studies, respectively.

Matched MeSH terms: Attention*
Extended-Range Prediction Model Using NSGA-III Optimized RNN-GRU-LSTM for Driver Stress and Drowsiness

Chui KT, Gupta BB, Liu RW, Zhang X, Vasant P, Thomas JJ

Sensors (Basel), 2021 Sep 25;21(19).
PMID: 34640732 DOI: 10.3390/s21196412

Road traffic accidents have been listed in the top 10 global causes of death for many decades. Traditional measures such as education and legislation have contributed to limited improvements in terms of reducing accidents due to people driving in undesirable statuses, such as when suffering from stress or drowsiness. Attention is drawn to predicting drivers' future status so that precautions can be taken in advance as effective preventative measures. Common prediction algorithms include recurrent neural networks (RNNs), gated recurrent units (GRUs), and long short-term memory (LSTM) networks. To benefit from the advantages of each algorithm, nondominated sorting genetic algorithm-III (NSGA-III) can be applied to merge the three algorithms. This is named NSGA-III-optimized RNN-GRU-LSTM. An analysis can be made to compare the proposed prediction algorithm with the individual RNN, GRU, and LSTM algorithms. Our proposed model improves the overall accuracy by 11.2-13.6% and 10.2-12.2% in driver stress prediction and driver drowsiness prediction, respectively. Likewise, it improves the overall accuracy by 6.9-12.7% and 6.9-8.9%, respectively, compared with boosting learning with multiple RNNs, multiple GRUs, and multiple LSTMs algorithms. Compared with existing works, this proposal offers to enhance performance by taking some key factors into account-namely, using a real-world driving dataset, a greater sample size, hybrid algorithms, and cross-validation. Future research directions have been suggested for further exploration and performance enhancement.

Matched MeSH terms: Attention
The Potential Role of miRNAs as Predictive Biomarkers in Neurodevelopmental Disorders

Juvale IIA, Che Has AT

J Mol Neurosci, 2021 Jul;71(7):1338-1355.
PMID: 33774758 DOI: 10.1007/s12031-021-01825-7

Neurodevelopmental disorders are defined as a set of abnormal brain developmental conditions marked by the early childhood onset of cognitive, behavioral, and functional deficits leading to memory and learning problems, emotional instability, and impulsivity. Autism spectrum disorder, attention-deficit/hyperactivity disorder, Tourette syndrome, fragile X syndrome, and Down's syndrome are a few known examples of neurodevelopmental disorders. Although they are relatively common in both developed and developing countries, very little is currently known about their underlying molecular mechanisms. Both genetic and environmental factors are known to increase the risk of neurodevelopmental disorders. Current diagnostic and screening tests for neurodevelopmental disorders are not reliable; hence, individuals with neurodevelopmental disorders are often diagnosed in the later stages. This negatively affects their prognosis and quality of life, prompting the need for a better diagnostic biomarker. Recent studies on microRNAs and their altered regulation in diseases have shed some light on the possible role they could play in the development of the central nervous system. This review attempts to elucidate our current understanding of the role that microRNAs play in neurodevelopmental disorders with the hope of utilizing them as potential biomarkers in the future.

Matched MeSH terms: Attention Deficit Disorder with Hyperactivity/diagnosis; Attention Deficit Disorder with Hyperactivity/genetics
Opisthorchis viverrini metacercarial infection in cyprinid fish in Nakhon Phanom Province, Northeastern Thailand

Laoprom N, Prathummang S, Chuangchaiya S, Navanesan S, Munajat MB, Suwannatrai AT, et al.

Trop Biomed, 2021 Jun 01;38(2):25-30.
PMID: 33973569 DOI: 10.47665/tb.38.2.033

Opisthorchiasis is endemic in parts of Southeast Asia, including the northern and northeastern regions of Thailand. In these regions, the transmission by fish intermediate hosts has received little attention. We investigated the intensity of Opisthorchis viverrini metacercariae (OV MC) in wild cyprinid fishes from five districts within the Nakhon Phanom Province, Northeast Thailand. Fishes were procured from local markets in five districts throughout three different seasons (hot, rainy and cold) between February 2018 and January 2019. The samples were identified, counted and weighed before metacercariae detection was performed via the artificial digestion method. A total of 2,149 freshwater fishes, representing 20 species were collected. The fish most commonly contaminated with OV MC were Anematichthys repasson and Hampala dispar. The intensity of OV MC in Nakhon Phanom was 0.23 OV MC/fish and varied among districts, ranging from 0.07 to 0.52. A low intensity of OV MC/fish (defined as <=1 cyst) was found in all three different seasons in the Nakhon Phanom Province; hot season (0.55), cold season (0.22) and the rainy season (0.13). The intensity of OV MC/fish was moderate (defined as >1 cyst) in the Renu Nakhon district (2.5) in the hot season. By fish species, H. dispar yielded the highest, with a moderate intensity of 2.1. In natural freshwater cyprinid fish in Nakhon Phanom, OV MC infection is endemic with intensity rates varying according to district, season and fish species.

Matched MeSH terms: Attention
Wearable patch delivery system for artificial pancreas health diagnostic-therapeutic application: A review

Nadia Ahmad NF, Nik Ghazali NN, Wong YH

Biosens Bioelectron, 2021 May 30;189:113384.
PMID: 34090154 DOI: 10.1016/j.bios.2021.113384

The advanced stimuli-responsive approaches for on-demand drug delivery systems have received tremendous attention as they have great potential to be integrated with sensing and multi-functional electronics on a flexible and stretchable single platform (all-in-one concept) in order to develop skin-integration with close-loop sensation for personalized diagnostic and therapeutic application. The wearable patch pumps have evolved from reservoir-based to matrix patch and drug-in-adhesive (single-layer or multi-layer) type. In this review, we presented the basic requirements of an artificial pancreas, surveyed the design and technologies used in commercial patch pumps available on the market and provided general information about the latest wearable patch pump. We summarized the various advanced delivery strategies with their mechanisms that have been developed to date and representative examples. Mechanical, electrical, light, thermal, acoustic and glucose-responsive approaches on patch form have been successfully utilized in the controllable transdermal drug delivery manner. We highlighted key challenges associated with wearable transdermal delivery systems, their research direction and future development trends.

Matched MeSH terms: Attention
Health Care Needs of Deaf Signers: The Case for Culturally Competent Health Care Providers

Jacob SA, Palanisamy UD, Napier J, Verstegen D, Dhanoa A, Chong EY

Acad Med, 2021 May 25.
PMID: 34039854 DOI: 10.1097/ACM.0000000000004181

There is a need for culturally competent health care providers (HCPs) to provide care to deaf signers, who are members of a linguistic and cultural minority group. Many deaf signers have lower health literacy levels due to deprivation of incidental learning opportunities and inaccessibility of health-related materials, increasing their risk for poorer health outcomes. Communication barriers arise because HCPs are ill-prepared to serve this population, with deaf signers reporting poor-quality interactions. This has translated to errors in diagnosis, patient nonadherence, and ineffective health information, resulting in mistrust of the health care system and reluctance to seek treatment. Sign language interpreters have often not received in-depth medical training, compounding the dynamic process of medical interpreting. HCPs should thus become more culturally competent, empowering them to provide cultural- and language-concordant services to deaf signers. HCPs who received training in cultural competency showed increased knowledge and confidence in interacting with deaf signers. Similarly, deaf signers reported more positive experiences when interacting with medically certified interpreters, HCPs with sign language skills, and practitioners who made an effort to improve communication. However, cultural competency programs within health care education remain inconsistent. Caring for deaf signers requires complex, integrated competencies that need explicit attention and practice repeatedly in realistic, authentic learning tasks ordered from simple to complex. Attention to the needs of deaf signers can start early in the curriculum, using examples of deaf signers in lectures and case discussions, followed by explicit discussions of Deaf cultural norms and the potential risks of low written and spoken language literacy. Students can subsequently engage in role plays with each other or representatives of the local signing deaf community. This would likely ensure that future HCPs are equipped with the knowledge and skills necessary to provide appropriate care and ensure equitable health care access for deaf signers.

Matched MeSH terms: Attention
Fulltext Microstructural behavior of magnetorheological elastomer undergoing durability evaluation by stress relaxation

Johari MAF, Mazlan SA, Nasef MM, Ubaidillah U, Nordin NA, Aziz SAA, et al.

Sci Rep, 2021 May 25;11(1):10936.
PMID: 34035434 DOI: 10.1038/s41598-021-90484-0

The widespread use of magnetorheological elastomer (MRE) materials in various applications has yet to be limited due to the fact that there are substantial deficiencies in current experimental and theoretical research on its microstructural durability behavior. In this study, MRE composed of silicon rubber (SR) and 70 wt% of micron-sized carbonyl iron particles (CIP) was prepared and subjected to stress relaxation evaluation by torsional shear load. The microstructure and particle distribution of the obtained MRE was evaluated by a field emission scanning electron microscopy (FESEM). The influence of constant low strain at 0.01% is the continuing concern within the linear viscoelastic (LVE) region of MRE. Stress relaxation plays a significant role in the life cycle of MRE and revealed that storage modulus was reduced by 8.7%, normal force has weakened by 27%, and stress performance was reduced by 6.88% along approximately 84,000 s test duration time. This time scale was the longest ever reported being undertaken in the MRE stress relaxation study. Novel micro-mechanisms that responsible for the depleted performance of MRE was obtained by microstructurally observation using FESEM and in-phase mode of atomic force microscope (AFM). Attempts have been made to correlate strain localization produced by stress relaxation, with molecular deformation in MRE amorphous matrix. Exceptional attention was focused on the development of molecular slippage, disentanglement, microplasticity, microphase separation, and shear bands. The relation between these microstructural phenomena and the viscoelastic properties of MRE was diffusely defined and discussed. The presented MRE is homogeneous with uniform distribution of CIP. The most significant recent developments of systematic correlation between the effects of microstructural deformation and durability performance of MRE under stress relaxation has been observed and evaluated.

Matched MeSH terms: Attention
Fulltext Thickness Optimization of Thin-Film Tandem Organic Solar Cell

Bangash KA, Kazmi SAA, Farooq W, Ayub S, Musarat MA, Alaloul WS, et al.

Micromachines (Basel), 2021 May 05;12(5).
PMID: 34062988 DOI: 10.3390/mi12050518

The polymer solar cells also known as organic solar cells (OSCs) have drawn attention due to their cynosure in industrial manufacturing because of their promising properties such as low weight, highly flexible, and low-cost production. However, low η restricts the utilization of OSCs for potential applications such as low-cost energy harvesting devices. In this paper, OSCs structure based on a triple-junction tandem scheme is reported with three different absorber materials to enhance the absorption of photons which in turn improves the η, as well as its correlating performance parameters. The investigated structure gives the higher value of η = 14.33% with Jsc = 16.87 (mA/m2), Voc = 1.0 (V), and FF = 84.97% by utilizing a stack of three different absorber layers with different band energies. The proposed structure was tested under 1.5 (AM) with 1 sun (W/m2). The impact of the top, middle, and bottom subcells' thickness on η was analyzed with a terse to find the optimum thickness for three subcells to extract high η. The optimized structure was then tested with different electrode combinations, and the highest η was recorded with FTO/Ag. Moreover, the effect of upsurge temperature was also demonstrated on the investigated schematic, and it was observed that the upsurge temperature affects the photovoltaic (PV) parameters of the optimized cell and η decreases from 14.33% to 11.40% when the temperature of the device rises from 300 to 400 K.

Matched MeSH terms: Attention
Review of chitosan composite as a heavy metal adsorbent: Material preparation and properties

Begum S, Yuhana NY, Md Saleh N, Kamarudin NHN, Sulong AB

Carbohydr Polym, 2021 May 01;259:117613.
PMID: 33673980 DOI: 10.1016/j.carbpol.2021.117613

A large amount of wastewater is typically discharged into water bodies and has extremely harmful effects to aquatic environments. The removal of heavy metals from water bodies is necessary for the safe consumption of water and human activities. The demand for seafood has considerably increased, and millions of tons of crustacean waste are discarded every year. These waste products are rich in a natural biopolymer known as chitin. The deacetylated form of chitin, chitosan, has attracted attention as an adsorbent. It is a biocompatible and biodegradable polymer that can be modified and converted to various derivatives. This review paper focuses on relevant literature on strategies for chemically modifying the biopolymer and its use in the removal of heavy metals from water and wastewater. The different aspects of chitosan-based derivatives and their preparation and application are elucidated. A list of chitosan-based composites, along with their adsorptivity and experimental conditions, are compiled.

Matched MeSH terms: Attention
Auditory attentional filter in the absence of masking noise

Anandan ES, Husain R, Seluakumaran K

Atten Percept Psychophys, 2021 May;83(4):1737-1751.
PMID: 33389676 DOI: 10.3758/s13414-020-02210-z

Signals containing attended frequencies are facilitated while those with unexpected frequencies are suppressed by an auditory filtering process. The neurocognitive mechanism underlying the auditory attentional filter is, however, poorly understood. The olivocochlear bundle (OCB), a brainstem neural circuit that is part of the efferent system, has been suggested to be partly responsible for the filtering via its noise-dependent antimasking effect. The current study examined the role of the OCB in attentional filtering, particularly the validity of the antimasking hypothesis, by comparing attentional filters measured in quiet and in the presence of background noise in a group of normal-hearing listeners. Filters obtained in both conditions were comparable, suggesting that the presence of background noise is not crucial for attentional filter generation. In addition, comparison of frequency-specific changes of the cue-evoked enhancement component of filters in quiet and noise also did not reveal any major contribution of background noise to the cue effect. These findings argue against the involvement of an antimasking effect in the attentional process. Instead of the antimasking effect mediated via medial olivocochlear fibers, results from current and earlier studies can be explained by frequency-specific modulation of afferent spontaneous activity by lateral olivocochlear fibers. It is proposed that the activity of these lateral fibers could be driven by top-down cortical control via a noise-independent mechanism. SIGNIFICANCE: The neural basis for auditory attentional filter remains a fundamental but poorly understood area in auditory neuroscience. The efferent olivocochlear pathway that projects from the brainstem back to the cochlea has been suggested to mediate the attentional effect via its noise-dependent antimasking effect. The current study demonstrates that the filter generation is mostly independent of the background noise, and therefore is unlikely to be mediated by the olivocochlear brainstem reflex. It is proposed that the entire cortico-olivocochlear system might instead be used to alter the hearing sensitivity during focus attention via frequency-specific modulation of afferent spontaneous activity.

Matched MeSH terms: Attention
Electroencephalography-detected neurophysiology of internet addiction disorder and internet gaming disorder in adolescents - A review

Sharifat H, Suppiah S

Med J Malaysia, 2021 05;76(3):401-413.
PMID: 34031341

INTRODUCTION: Internet Addiction Disorder (IAD) is an umbrella term for various types of Internet-based behavioural addiction, whereas Internet Gaming Disorder (IGD) addresses a specific type of IAD that is postulated to be due to a lack of control in impulse inhibition. IGD is an area of concern in the Diagnostic and Statistics Manual of Mental Disorders (DSM-5), which can be objectively assessed by dysfunctional behaviour and the increasing time of being online, particularly during the COVID-19 pandemic. Electroencephalography (EEG) identifies amplitude changes in the evoked response potential (ERP) among IGDs, correlated with underlying comorbidities.
MATERIALS AND METHODS: A scoping review was performed to elaborate on the research regarding resting-state EEG and task-based EEG, particularly for Go/No-go paradigms pertaining to subjects with IAD or specifically IGD. The role of EEG was identified in its diagnostic capability to identify the salient changes that occurred in the response to reward network and the executive control network, using restingstate and task-based EEG. The implication of using EEG in monitoring the therapy for IAD and IGD was also reviewed.
RESULTS: EEG generally revealed reduced beta waves and increased theta waves in addicts. IGD with depression demonstrated increased theta and decreased alpha waves. Whereas increased P300, a late cognitive ERP component, was frequently associated with impaired excessive allocation of attentional resources of the IAD towards addiction-specific cues. IGD had increased whole brain delta waves at baseline, which showed significant reduction post therapy.
CONCLUSION: EEG can identify distinct neurophysiological changes among Internet Addiction Disorder and Internet Gaming Disorder that are akin to substance abuse disorders.

Matched MeSH terms: Attention/physiology*
Fulltext Potential for Natural Fiber Reinforcement in PLA Polymer Filaments for Fused Deposition Modeling (FDM) Additive Manufacturing: A Review

Lee CH, Padzil FNBM, Lee SH, Ainun ZMA, Abdullah LC

Polymers (Basel), 2021 Apr 27;13(9).
PMID: 33925266 DOI: 10.3390/polym13091407

In this review, the potential of natural fiber and kenaf fiber (KF) reinforced PLA composite filament for fused deposition modeling (FDM) 3D-printing technology is highlighted. Additive manufacturing is a material-processing method in which the addition of materials layer by layer creates a three-dimensional object. Unfortunately, it still cannot compete with conventional manufacturing processes, and instead serves as an economically effective tool for small-batch or high-variety product production. Being preformed of composite filaments makes it easiest to print using an FDM 3D printer without or with minimum alteration to the hardware parts. On the other hand, natural fiber-reinforced polymer composite filaments have gained great attention in the market. However, uneven printing, clogging, and the inhomogeneous distribution of the fiber-matrix remain the main challenges. At the same time, kenaf fibers are one of the most popular reinforcements in polymer composites. Although they have a good record on strength reinforcement, with low cost and light weight, kenaf fiber reinforcement PLA filament is still seldom seen in previous studies. Therefore, this review serves to promote kenaf fiber in PLA composite filaments for FDM 3D printing. To promote the use of natural fiber-reinforced polymer composite in AM, eight challenges must be solved and carried out. Moreover, some concerns arise to achieve long-term sustainability and market acceptability of KF/PLA composite filaments.

Matched MeSH terms: Attention
Fulltext Physical Properties of Thermoplastic Starch Derived from Natural Resources and Its Blends: A Review

Diyana ZN, Jumaidin R, Selamat MZ, Ghazali I, Julmohammad N, Huda N, et al.

Polymers (Basel), 2021 Apr 26;13(9).
PMID: 33925897 DOI: 10.3390/polym13091396

Thermoplastic starch composites have attracted significant attention due to the rise of environmental pollutions induced by the use of synthetic petroleum-based polymer materials. The degradation of traditional plastics requires an unusually long time, which may lead to high cost and secondary pollution. To solve these difficulties, more petroleum-based plastics should be substituted with sustainable bio-based plastics. Renewable and natural materials that are abundant in nature are potential candidates for a wide range of polymers, which can be used to replace their synthetic counterparts. This paper focuses on some aspects of biopolymers and their classes, providing a description of starch as a main component of biopolymers, composites, and potential applications of thermoplastics starch-based in packaging application. Currently, biopolymer composites blended with other components have exhibited several enhanced qualities. The same behavior is also observed when natural fibre is incorporated with biopolymers. However, it should be noted that the degree of compatibility between starch and other biopolymers extensively varies depending on the specific biopolymer. Although their efficacy is yet to reach the level of their fossil fuel counterparts, biopolymers have made a distinguishing mark, which will continue to inspire the creation of novel substances for many years to come.

Matched MeSH terms: Attention
Chitosan modifications for adsorption of pollutants - A review

Saheed IO, Oh WD, Suah FBM

J Hazard Mater, 2021 04 15;408:124889.
PMID: 33418525 DOI: 10.1016/j.jhazmat.2020.124889

In recent times, research interest into the development of biodegradable, cost-effective and environmental friendly adsorbents with favourable properties for adsorption of pollutants is a challenge. Modification of chitosan via different physical and chemical methods have gained attention as a promising approach for removing organic (such as dyes and pharmaceuticals) and inorganic (such as metal/metal ions) pollutants from aqueous medium. In this regard, researchers have reported grafting and cross-linking approach among others as a potentially useful method for chitosan's modification for improved adsorption efficiency with respect to pollutant uptake. This article reviews the trend in chitosan modification, with regards to the summary of some recently published works on modification of chitosan and their adsorption application in pollutants (metal ion, dyes and pharmaceuticals) removal from aqueous medium. The review uniquely highlights some common cross-linkers and grafting procedures for chitosan modification, their influence on structure and adsorption capacity of modified-chitosan with respect to pollutants removal. Findings revealed that the performance of modified chitosan for adsorption of pollutants depends largely on the modification method adopted, materials used for the modification and adsorption experimental conditions. Cross-linking is commonly utilized for improving the chemical and mechanical stabilities of chitosan but usually decreases adsorption capacity of chitosan/modified-chitosan for adsorption of pollutants. However, literature survey revealed that adsorption capacity of cross-linked chitosan based materials have been enhanced in recently published works either by grafting, incorporation of solid adsorbents (e.g metals, clays and activated carbon) or combination of both prior to cross-linking.

Matched MeSH terms: Attention

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