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1.
Front Mol Neurosci ; 17: 1368905, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38476460

RESUMO

Burn injuries are devastating traumas, often leading to life-long consequences that extend beyond the observable burn scar. In the context of the nervous system, burn injury patients commonly develop chronic neurological disorders and have been suggested to have impaired motor cortex function, but the long-lasting impact on neurons and glia in the brain is unknown. Using a mouse model of non-severe burn injury, excitatory and inhibitory neurons in the primary motor cortex were labelled with fluorescent proteins using adeno-associated viruses (AAVs). A total of 5 weeks following the burn injury, virus labelled excitatory and inhibitory neurons were isolated using fluorescence-activated cell sorting (FACS). In addition, microglia and astrocytes from the remaining cortical tissue caudal to the motor cortex were immunolabelled and isolated with FACS. Whole transcriptome RNA-sequencing was used to identify any long-lasting changes to gene expression in the different cell types. RNA-seq analysis showed changes to the expression of a small number of genes with known functions in excitatory neurons and microglia, but not in inhibitory neurons or astrocytes. Specifically, genes related to GABA-A receptors in excitatory neurons and several cellular functions in microglia were found to be downregulated in burn injured mice. These findings suggest that non-severe burn injuries lead to long lasting transcriptomic changes in the brain, but only in specific cell types. Our findings provide a broad overview of the long-lasting impact of burn injuries on the central nervous system which may help identify potential therapeutic targets to prevent neurological dysfunction in burn patients.

2.
Ophthalmology ; 2024 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-38336283

RESUMO

TOPIC: This systematic review and meta-analysis aims to clarify the association of cataract surgery with cognitive impairment and dementia. CLINICAL RELEVANCE: The association between vision impairment and cognitive decline is well-established. However, the cognitive benefits of cataract surgery are less clear. Given the lack of cure for dementia, identifying modifiable risk factors is key in caring for patients with cognitive deficits. METHODS: The study was conducted following Preferred Reporting Items for Systematic Review and Meta-analyses guidelines. PubMed, Embase, and Cochrane Library were searched from inception through October 11, 2022, for studies reporting the effect of cataract surgery on cognitive impairment and dementia. We pooled maximally adjusted hazard ratios (HRs) for dichotomous outcomes and ratio of means (RoM) for continuous outcomes using a random-effects model. Heterogeneity was examined using sensitivity and subgroup analyses. The quality of evidence was evaluated using the Newcastle-Ottawa scale, Cochrane risk-of-bias tool for randomized trials, and Grading of Recommendations, Assessment, Development and Evaluations (GRADE) guidelines. RESULTS: This review included 24 articles comprising 558 276 participants, of which 19 articles were analyzed qualitatively. The bias of studies ranged from low to moderate, and GRADE extended from very low to low. Cataract surgery was associated with a 25% reduced risk of long-term cognitive decline compared with those with uncorrected cataracts (HR, 0.75; 95% confidence interval [CI], 0.72-0.78). This cognitive benefit was seen across various cognitive outcomes and remained robust to sensitivity analyses. Participants who underwent cataract surgery showed a similar risk of long-term cognitive decline as healthy controls without cataracts (HR, 0.84; 95% CI, 0.66-1.06). Additionally, cataract surgery was associated with a 4% improvement in short-term cognitive test scores among participants with normal cognition (RoM, 0.96; 95% CI, 0.94-0.99), but no significant association was observed among participants with preexisting cognitive impairment. DISCUSSION: Cataract surgery may be associated with a lower risk of cognitive impairment and dementia, and cataract-associated vision impairment may be a modifiable risk factor for cognitive decline. Physicians should be aware of the cognitive sequelae of cataracts and the possible benefits of surgery. The cognitive benefits of cataract surgery should be investigated further in randomized trials. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

3.
Bioresour Technol ; 393: 129989, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37931765

RESUMO

The effect of tissue-specific biochemical heterogeneities of lignocellulosic biomass on biomass deconstruction is best understood through confocal laser scanning microscopy (CLSM) combined with immunohistochemistry. However, this process can be challenging, given the fragility of plant materials, and is generally not able to observe changes in the same section of biomass during both pretreatment and enzymatic hydrolysis. To overcome this challenge, a custom polydimethylsiloxane (PDMS) microfluidic imaging reactor was constructed using standard photolithographic techniques. As proof of concept, CLSM was performed on 60 µm-thick corn stem sections during pretreatment and enzymatic hydrolysis using the imaging reactor. Based on the fluorescence images, the less lignified parenchyma cell walls were more susceptible to pretreatment than the lignin-rich vascular bundles. During enzymatic hydrolysis, the highly lignified protoxylem cell wall was the most resistant, remaining unhydrolyzed even after 48 h. Therefore, imaging thin whole biomass sections was useful to obtain tissue-specific changes during biomass deconstruction.


Assuntos
Lignina , Microfluídica , Biomassa , Hidrólise , Imagem com Lapso de Tempo
4.
Int J Integr Care ; 23(4): 11, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38020415

RESUMO

Introduction: The Esther Network (EN) person-centred care (PCC) advocacy training aims to promote person-centred attitudes among health practitioners in Singapore. This study aimed to assess the relationship between the training and practitioners' PCC attributes over a 3-month period, and to explore power sharing by examining the PCC dimensions of "caring about the service user as a whole person" and the "sharing of power, control and information". Methods: A repeated-measure study design utilising the Patient-Practitioner Orientation Scale (PPOS), was administered to 437 training participants at three time points - before training (T1), immediately after (T2) and three months after training (T3). A five-statement questionnaire captured knowledge of person-centred care at T1 and T2. An Overall score, Caring and Sharing sub-scores were derived from the PPOS. Scores were ranked and divided into three groups (high, medium and low). Ordinal Generalised Estimating Equation (GEE) model analysed changes in PPOS scores over time. Results: A single, short-term training appeared to result in measurable improvements in person-centredness of health practitioners, with slight attenuation at T3. There was greater tendency to "care" than to "share power" with service users across all three time points, but the degree of improvement was larger for sharing after training. The change in overall person-centred scores varied by sex and profession (females score higher than males, allied health showed a smaller attenuation at T3). Conclusion: Training as a specific intervention, appeared to have potential to increase health practitioners' person-centredness but the aspect of equalising power was harder to achieve within a hierarchical structure and clinician-centric culture. An ongoing network to build relationships, and a supportive system to facilitate individual and organisational reflexivity can reinforce learning.

5.
Microbiome ; 11(1): 224, 2023 10 14.
Artigo em Inglês | MEDLINE | ID: mdl-37838714

RESUMO

BACKGROUND: Plastic-degrading microbial isolates offer great potential to degrade, transform, and upcycle plastic waste. Tandem chemical and biological processing of plastic wastes has been shown to substantially increase the rates of plastic degradation; however, the focus of this work has been almost entirely on microbial isolates (either bioengineered or naturally occurring). We propose that a microbial community has even greater potential for plastic upcycling. A microbial community has greater metabolic diversity to process mixed plastic waste streams and has built-in functional redundancy for optimal resilience. RESULTS: Here, we used two plastic-derivative degrading communities as a model system to investigate the roles of specialist and generalist species within the microbial communities. These communities were grown on five plastic-derived substrates: pyrolysis treated high-density polyethylene, chemically deconstructed polyethylene terephthalate, disodium terephthalate, terephthalamide, and ethylene glycol. Short-read metagenomic and metatranscriptomic sequencing were performed to evaluate activity of microorganisms in each treatment. Long-read metagenomic sequencing was performed to obtain high-quality metagenome assembled genomes and evaluate division of labor. CONCLUSIONS: Data presented here show that the communities are primarily dominated by Rhodococcus generalists and lower abundance specialists for each of the plastic-derived substrates investigated here, supporting previous research that generalist species dominate batch culture. Additionally, division of labor may be present between Hydrogenophaga terephthalate degrading specialists and lower abundance protocatechuate degrading specialists. Video Abstract.


Assuntos
Microbiota , Ácidos Ftálicos , Polietileno/química , Polietileno/metabolismo , Metagenoma
7.
Int J Med Inform ; 178: 105193, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-37672981

RESUMO

BACKGROUND AND OBJECTIVES: The disclosure of personal health information in electronic health records (eHR) highlights privacy and security concerns that are complicated by the digitization and interoperability of health records. Hong Kong's Electronic Health Record Sharing System (eHRSS), introduced in March 2016, enables eHR sharing among public and private health services upon the consent of patients. Based on a September 2021 survey, this study examined the specific context of Hong Kong, patient and public perceptions on the security and privacy of eHR sharing, correlation of trust with personal privacy and security concerns, and how perceptions affect health care-related decisions. METHODS: Using a random sample of householders aged 45-70 years, the study conducted a questionnaire survey on respondents' awareness, perceived benefits, and obstacles to participating in the eHRSS, and the impact of their perceptions on health care-related decisions. A focus group discussion with 13 participants further explored views on the security of Hong Kong's eHRSS and their readiness to support the system. RESULTS: The study analyzed data from 400 responses. The findings showed a low degree of awareness of the eHRSS. Privacy and security concerns were impeding factors in the sharing of information; half of the respondents reported being concerned over their personal health information being part of the eHRSS. The majority (86.9%) expressed conditional support for the sharing of information. Despite their concerns on security and privacy, 66.5% and 77.9%, respectively, would not withhold information nor postpone the seeking of medical care based on those concerns. Participants in the focus group expressed concerns regarding eHRSS registration, data leaks, information accuracy, and the potential prejudice that may result in discrimination and inequality in health care provision. CONCLUSIONS: Satisfaction with the health care services played a role in the trust reposed in the Hospital Authority and health care providers and institutions. Security and privacy were decisive factors in respodents' refusal to seek care from physicians who had violated their privacy. Respondents expressed greater interest in sharing their information if measures were in place for anonymization and punishing data misuse. Ensuring rights of control toward information sharing would inspire greater confidence among patients.


Assuntos
Confidencialidade , Registros Eletrônicos de Saúde , Humanos , Hong Kong , Opinião Pública , Privacidade
8.
Microbiol Spectr ; 11(4): e0036223, 2023 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-37260392

RESUMO

Over half of the world's plastic waste is landfilled, where it is estimated to take hundreds of years to degrade. Given the continued use and disposal of plastic products, it is vital that we develop fast and effective ways to utilize plastic waste. Here, we explore the potential of tandem chemical and biological processing to process various plastics quickly and effectively. Four samples of compost or sediment were used to set up enrichment cultures grown on mixtures of compounds, including disodium terephthalate and terephthalic acid (monomers of polyethylene terephthalate), compounds derived from the chemical deconstruction of polycarbonate, and pyrolysis oil derived from high-density polyethylene plastics. Established enrichment communities were also grown on individual substrates to investigate the substrate preferences of different taxa. Biomass harvested from the cultures was characterized using 16S rRNA gene amplicon sequencing and shotgun metagenomic sequencing. These data reveal low-diversity microbial communities structured by differences in culture inoculum, culture substrate source plastic type, and time. Microbial populations from the classes Alphaproteobacteria, Gammaproteobacteria, Actinobacteria, and Acidobacteriae were significantly enriched when grown on substrates derived from high-density polyethylene and polycarbonate. The metagenomic data contain abundant aromatic and aliphatic hydrocarbon degradation genes relevant to the biodegradation of deconstructed plastic substrates used here. We show that microbial populations from diverse environments are capable of growth on substrates derived from the chemical deconstruction or pyrolysis of multiple plastic types and that paired chemical and biological processing of plastics should be further developed for industrial applications to manage plastic waste. IMPORTANCE The durability and impermeable nature of plastics have made them a popular material for numerous applications, but these same qualities make plastics difficult to dispose of, resulting in massive amounts of accumulated plastic waste in landfills and the natural environment. Since plastic use and disposal are projected to increase in the future, novel methods to effectively break down and dispose of current and future plastic waste are desperately needed. We show that the products of chemical deconstruction or pyrolysis of plastic can successfully sustain the growth of low-diversity microbial communities. These communities were enriched from multiple environmental sources and are capable of degrading complex xenobiotic carbon compounds. This study demonstrates that tandem chemical and biological processing can be used to degrade multiple types of plastics over a relatively short period of time and may be a future avenue for the mitigation of rapidly accumulating plastic waste.


Assuntos
Plásticos , Polietileno , Plásticos/metabolismo , Polietileno/metabolismo , RNA Ribossômico 16S/genética , Polietilenotereftalatos/metabolismo , Bactérias
9.
Microbiol Resour Announc ; 12(7): e0130422, 2023 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-37338395

RESUMO

We report the metagenome sequences of two microbial cultures that were grown with chemically deconstructed plastic products as their sole carbon source. These metagenomes will provide insights into the metabolic capabilities of cultures grown on deconstructed plastics and can serve as a starting point for the identification of novel plastic degradation mechanisms.

10.
J Ind Microbiol Biotechnol ; 50(1)2023 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-37061790

RESUMO

Waste plastic presently accumulates in landfills or the environment. While natural microbial metabolisms can degrade plastic polymers, biodegradation of plastic is very slow. This study demonstrates that chemical deconstruction of polyethylene terephthalate (PET) with ammonium hydroxide can replace the rate limiting step (depolymerization) and by producing plastic-derived terephthalic acid and terephthalic acid monoamide. The deconstructed PET (DCPET) is neutralized with phosphoric acid prior to bioprocessing, resulting in a product containing biologically accessible nitrogen and phosphorus from the process reactants. Three microbial consortia obtained from compost and sediment degraded DCPET in ultrapure water and scavenged river water without addition of nutrients. No statistically significant difference was observed in growth rate compared to communities grown on DCPET in minimal culture medium. The consortia were dominated by Rhodococcus spp., Hydrogenophaga spp., and many lower abundance genera. All taxa were related to species known to degrade aromatic compounds. Microbial consortia are known to confer flexibility in processing diverse substrates. To highlight this, we also demonstrate that two microbial consortia can grow on similarly deconstructed polyesters, polyamides, and polyurethanes in water instead of medium. Our findings suggest that microbial communities may enable flexible bioprocessing of mixed plastic wastes when coupled with chemical deconstruction.


Assuntos
Microbiota , Plásticos , Plásticos/metabolismo , Hidróxido de Amônia , Biodegradação Ambiental , Água
11.
Trends Biotechnol ; 41(2): 184-196, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-36058768

RESUMO

Most polyethylene terephthalate (PET) plastic waste is landfilled or pollutes the environment. Additionally, global food production must increase to support the growing population. This article explores the feasibility of using microorganisms in an industrial system that upcycles PET into edible microbial protein powder to solve both problems simultaneously. Many microorganisms can utilize plastics as feedstock, and the resultant microbial biomass contains fats, nutrients, and proteins similar to those found in human diets. While microbial degradation of PET is promising, biological PET depolymerization is too slow to resolve the global plastic crisis and projected food shortages. Evidence reviewed here suggests that by coupling chemical depolymerization and biological degradation of PET, and using cooperative microbial communities, microbes can efficiently convert PET waste into food.


Assuntos
Microbiota , Plásticos , Humanos , Plásticos/química , Polietilenotereftalatos/química , Polietilenotereftalatos/metabolismo , Alimentos , Biomassa
12.
Cancer Drug Resist ; 6(4): 768-787, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38263984

RESUMO

The use of immune checkpoint inhibitors (ICIs) has increased exponentially in the past decade, although its progress specifically for breast cancer has been modest. The first U.S. Food and Drug Administration approval for ICI in breast cancer came in 2019, eight years after the first-ever approval of an ICI. At present, current indications for ICIs are relevant only to a subset of patients with triple-negative breast cancer, or those displaying high microsatellite instability or deficiency in the mismatch repair protein pathway. With an increasing understanding of the limitations of using ICIs, which stem from breast cancer being innately poorly immunogenic, as well as the presence of various intrinsic and acquired resistance pathways, ongoing trials are evaluating different combination therapies to overcome these barriers. In this review, we aim to describe the development timeline of ICIs and resistance mechanisms limiting their utility, and summarise the available approaches and ongoing trials relevant to overcoming each resistance mechanism.

13.
PLoS One ; 17(10): e0276385, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36264909

RESUMO

BACKGROUND: Falls and fall-related injuries in older adults are a leading cause of disability and death. Evidence has shown the benefits of exercises in improving functional outcomes and reducing fall rates among community-dwelling older adults. However, there is lack of effective community-based single exercise intervention for a broad population of older adults who are at high risk for falls. We aim to evaluate the effectiveness of Steady Feet (SF), a 6-month tailored community fall prevention exercise programme for improving functional outcomes. SF classes are facilitated by community fitness instructors and an exercise video. The main outcome is between-group changes in short physical performance battery (SPPB) scores. Secondary outcomes include balance confidence, fear of falling, quality of life, fall rates, and cost effectiveness. METHODS: We present the design of a 6-month randomised controlled trial of 260 older adults (≥ 60 years old). Individuals will be randomised in a 1:1 allocation ratio to the SF group or usual care group. Participants will be assessed at baseline, 3-month, and 6-month. Data on socio-demographics, co-morbidities, balance confidence, fear of falling, quality of life, physical activity level, rate of perceived exertion, fall(s) history, healthcare utilisation and cost, and satisfaction levels will be collected. Participants will also undergo functional assessments such as SPPB. Moreover, providers' satisfaction and feedback will be obtained at 3-month. DISCUSSION: An effective community fall prevention programme may lead to improved functional outcomes and reduced fall rates. Findings will also help inform the implementation and scaling of SF nation-wide. TRIAL REGISTRATION: Clinicaltrials.gov registration: NCT04801316. Registered on 15th March 2021.


Assuntos
Acidentes por Quedas , Qualidade de Vida , Humanos , Idoso , Pessoa de Meia-Idade , Acidentes por Quedas/prevenção & controle , Medo , Terapia por Exercício/métodos , Vida Independente , Ensaios Clínicos Controlados Aleatórios como Assunto
14.
Biotechnol Biofuels Bioprod ; 15(1): 116, 2022 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-36310161

RESUMO

BACKGROUND: Developing economically viable pathways to produce renewable energy has become an important research theme in recent years. Lignocellulosic biomass is a promising feedstock that can be converted into second-generation biofuels and bioproducts. Global warming has adversely affected climate change causing many environmental changes that have impacted earth surface temperature and rainfall patterns. Recent research has shown that environmental growth conditions altered the composition of drought-stressed switchgrass and directly influenced the extent of biomass conversion to fuels by completely inhibiting yeast growth during fermentation. Our goal in this project was to find a way to overcome the microbial inhibition and characterize specific compounds that led to this inhibition. Additionally, we also determined if these microbial inhibitors were plant-generated compounds, by-products of the pretreatment process, or a combination of both. RESULTS: Switchgrass harvested in drought (2012) and non-drought (2010) years were pretreated using Ammonia Fiber Expansion (AFEX). Untreated and AFEX processed samples were then extracted using solvents (i.e., water, ethanol, and ethyl acetate) to selectively remove potential inhibitory compounds and determine whether pretreatment affects the inhibition. High solids loading enzymatic hydrolysis was performed on all samples, followed by fermentation using engineered Saccharomyces cerevisiae. Fermentation rate, cell growth, sugar consumption, and ethanol production were used to evaluate fermentation performance. We found that water extraction of drought-year switchgrass before AFEX pretreatment reduced the inhibition of yeast fermentation. The extracts were analyzed using liquid chromatography-mass spectrometry (LC-MS) to detect compounds enriched in the extracted fractions. Saponins, a class of plant-generated triterpene or steroidal glycosides, were found to be significantly more abundant in the water extracts from drought-year (inhibitory) switchgrass. The inhibitory nature of the saponins in switchgrass hydrolysate was validated by spiking commercially available saponin standard (protodioscin) in non-inhibitory switchgrass hydrolysate harvested in normal year. CONCLUSIONS: Adding a water extraction step prior to AFEX-pretreatment of drought-stressed switchgrass effectively overcame inhibition of yeast growth during bioethanol production. Saponins appear to be generated by the plant as a response to drought as they were significantly more abundant in the drought-stressed switchgrass water extracts and may contribute toward yeast inhibition in drought-stressed switchgrass hydrolysates.

15.
J Health Popul Nutr ; 40(1): 52, 2021 12 11.
Artigo em Inglês | MEDLINE | ID: mdl-34895351

RESUMO

BACKGROUND: Nutrition literacy refers to an individual's knowledge, motivation and competencies to access, process and understand nutrition information to make nutrition-related decisions. It is known to influence dietary habits of individuals including older adults. This cross-sectional study was designed to: (1) understand the nutrition knowledge, competencies and attitudes of community-dwelling older adults in Singapore, (2) examine the differences between their nutrition knowledge, and socio-demographic factors, competencies and attitudes and (3) identify factors associated with better nutrition knowledge in older healthy adults in Singapore. METHODS: A total of 400 (183 males and 217 females) nourished community-dwelling older adults aged 65 years and above took part in this study. Malnutrition Universal Screening Tool (MUST) was used to determine individuals who were at low risk of undernutrition. Nutrition knowledge, competencies, attitudes and sources of nutrition information were measured using a locally developed scale. Nutrition knowledge scores were summed to form the nutrition knowledge index (NKI). Associations between NKI, competencies, attitudes and socio-demographic variables were examined using Chi-square and Fisher's exact tests. Factors associated with NKI were determined using a stepwise regression model with resampling-based methods for model averaging. RESULTS: Bivariate analyses found significant differences in NKI scores for gender, monthly household earnings, type of housing, the self-reported ability to seek and understand nutrition information and having access to help from family/friends. Females had higher NKI scores compared to males (p < 0.001). Compared to females, more males left food decisions to others (p < 0.001), and fewer males reported consuming home-cooked food (p = 0.016). Differences in educational level were found for competencies like the self-reported ability to seek (p < 0.001) and verify nutrition information (p < 0.001). Stepwise regression analysis showed that being female, Chinese, self-reported ability to understand nutrition information and having access to help from family/friends were associated with higher NKI scores. CONCLUSIONS: Our study revealed that nutrition knowledge of older males in Singapore was lower than females and more left food decisions to others. Nutrition education programs could be targeted at both the older male, their caregivers and minority ethnic groups. Trial Registration This study was registered on 7 August 2017 at clinicaltrials.gov (ref. NCT03240952).


Assuntos
Nível de Saúde , Vida Independente , Idoso , Atitude , Estudos Transversais , Feminino , Humanos , Masculino , Singapura
16.
Biotechnol Biofuels ; 14(1): 179, 2021 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-34507592

RESUMO

BACKGROUND: Environmental factors, such as weather extremes, have the potential to cause adverse effects on plant biomass quality and quantity. Beyond adversely affecting feedstock yield and composition, which have been extensively studied, environmental factors can have detrimental effects on saccharification and fermentation processes in biofuel production. Only a few studies have evaluated the effect of these factors on biomass deconstruction into biofuel and resulting fuel yields. This field-to-fuel evaluation of various feedstocks requires rigorous coordination of pretreatment, enzymatic hydrolysis, and fermentation experiments. A large number of biomass samples, often in limited quantity, are needed to thoroughly understand the effect of environmental conditions on biofuel production. This requires greater processing and analytical throughput of industrially relevant, high solids loading hydrolysates for fermentation, and led to the need for a laboratory-scale high solids experimentation platform. RESULTS: A field-to-fuel platform was developed to provide sufficient volumes of high solids loading enzymatic hydrolysate for fermentation. AFEX pretreatment was conducted in custom pretreatment reactors, followed by high solids enzymatic hydrolysis. To accommodate enzymatic hydrolysis of multiple samples, roller bottles were used to overcome the bottlenecks of mixing and reduced sugar yields at high solids loading, while allowing greater sample throughput than possible in bioreactors. The roller bottle method provided 42-47% greater liquefaction compared to the batch shake flask method for the same solids loading. In fermentation experiments, hydrolysates from roller bottles were fermented more rapidly, with greater xylose consumption, but lower final ethanol yields and CO2 production than hydrolysates generated with shake flasks. The entire platform was tested and was able to replicate patterns of fermentation inhibition previously observed for experiments conducted in larger-scale reactors and bioreactors, showing divergent fermentation patterns for drought and normal year switchgrass hydrolysates. CONCLUSION: A pipeline of small-scale AFEX pretreatment and roller bottle enzymatic hydrolysis was able to provide adequate quantities of hydrolysate for respirometer fermentation experiments and was able to overcome hydrolysis bottlenecks at high solids loading by obtaining greater liquefaction compared to batch shake flask hydrolysis. Thus, the roller bottle method can be effectively utilized to compare divergent feedstocks and diverse process conditions.

17.
J Vis Exp ; (158)2020 04 18.
Artigo em Inglês | MEDLINE | ID: mdl-32364543

RESUMO

Lignocellulosic materials are plant-derived feedstocks, such as crop residues (e.g., corn stover, rice straw, and sugar cane bagasse) and purpose-grown energy crops (e.g., miscanthus, and switchgrass) that are available in large quantities to produce biofuels, biochemicals, and animal feed. Plant polysaccharides (i.e., cellulose, hemicellulose, and pectin) embedded within cell walls are highly recalcitrant towards conversion into useful products. Ammonia fiber expansion (AFEX) is a thermochemical pretreatment that increases accessibility of polysaccharides to enzymes for hydrolysis into fermentable sugars. These released sugars can be converted into fuels and chemicals in a biorefinery. Here, we describe a laboratory-scale batch AFEX process to produce pretreated biomass on the gram-scale without any ammonia recycling. The laboratory-scale process can be used to identify optimal pretreatment conditions (e.g., ammonia loading, water loading, biomass loading, temperature, pressure, residence time, etc.) and generates sufficient quantities of pretreated samples for detailed physicochemical characterization and enzymatic/microbial analysis. The yield of fermentable sugars from enzymatic hydrolysis of corn stover pretreated using the laboratory-scale AFEX process is comparable to pilot-scale AFEX process under similar pretreatment conditions. This paper is intended to provide a detailed standard operating procedure for the safe and consistent operation of laboratory-scale reactors for performing AFEX pretreatment of lignocellulosic biomass.


Assuntos
Amônia/farmacologia , Biomassa , Lignina/metabolismo , Biocombustíveis , Reatores Biológicos , Glucose/análise , Poaceae , Temperatura , Xilose/análise
18.
PLoS One ; 14(10): e0223222, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31596873

RESUMO

OBJECTIVES: Aging is associated with low muscle mass and has been linked to adverse health outcomes. The objectives of this cross-sectional study were: (1) to describe anthropometry, body composition, appendicular skeletal muscle mass index (ASMI; appendicular skeletal muscle mass/height2), and prevalence of low ASMI in older people with normal nutritional status (Malnutrition Universal Screening Tool score = 0); (2) to determine factors associated with ASMI, and odds ratios of having low ASMI. METHODS: SHIELD is a study of community-dwelling older people aged 65 years and above in Singapore. ASMI was determined using bioelectrical impedance analysis and low ASMI was defined as <7.0 kg/m2 for males and <5.7 kg/m2 for females (Asian Working Group for Sarcopenia, 2014). RESULTS: A total of 400 older people (183 males and 217 females) took part in this study. The overall prevalence of low ASMI was 20.6% (15.5% in males and 24.9% in females). Females had significantly lower ASMI than males (P < 0.0001), age was inversely associated with ASMI (P = 0.0024) while BMI and calf circumference were positively associated with ASMI (both P < 0.0001) in the total cohort. In addition, ASMI was positively associated with bone mass in both genders (both P < 0.0001). After adjusting for covariates, the odds ratios of having low ASMI with every 1 year and 10 years increase in age were 1.13 (95% CI: 1.06, 1.20) and 3.36 (95% CI: 1.82, 6.21) respectively. CONCLUSIONS: The high prevalence of low ASMI in community-dwelling older people with normal nutritional status highlights the need for early screening. There was a strong inverse association between age and ASMI while BMI, calf circumference and bone mass were positively associated with ASMI. These findings will give further weight to the importance and development of public health strategies in maintaining and improving muscle health in this population group.


Assuntos
Vida Independente , Músculo Esquelético/anatomia & histologia , Idoso , Estudos de Coortes , Feminino , Humanos , Modelos Lineares , Masculino , Tamanho do Órgão , Singapura
19.
Int J Law Psychiatry ; 54: 1-15, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28962682

RESUMO

Online bullying as a form of online aggression is an increasingly growing phenomenon that is experienced by all age groups. Apart from the use of technology, online bullying shares the same attributes as conventional bullying. This includes a power imbalance vis-a-vis the bully and the victim and the victims' feeling of helplessness. Its impact however, is greater resulting in severe psychological, social and mental health problems. Because online bullying presents a new type of challenge for lawmakers, educators and parents, there may not be a single solution to this social problem. The paper examines the existing laws in Hong Kong that may apply to online bullying, assessing its effectiveness as a means in redressing the power imbalance. It also looks at non-legal measures that can be adopted in Hong Kong to tackle the problem.


Assuntos
Bullying/estatística & dados numéricos , Direito Penal , Internet , Adolescente , Adulto , Agressão , Austrália , Criança , Vítimas de Crime/psicologia , Direito Penal/legislação & jurisprudência , Difamação/legislação & jurisprudência , Difamação/psicologia , Feminino , Hong Kong , Humanos , Internet/legislação & jurisprudência , Masculino , Serviços de Saúde Escolar , Instituições Acadêmicas , Rede Social , Inquéritos e Questionários , Reino Unido , Estados Unidos , Local de Trabalho , Adulto Jovem
20.
Bioresour Technol ; 245(Pt A): 242-249, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28892697

RESUMO

This work investigated the impact of two alkaline pretreatments, ammonia fiber expansion (AFEX) and alkaline hydrogen peroxide (AHP) delignification performed over a range of conditions on the properties of corn stover and switchgrass. Changes in feedstock properties resulting from pretreatment were subsequently compared to enzymatic hydrolysis yields to examine the relationship between enzymatic hydrolysis and cell wall properties. The pretreatments function to increase enzymatic hydrolysis yields through different mechanisms; AFEX pretreatment through lignin relocalization and some xylan solubilization and AHP primarily through lignin solubilization. An important outcome of this work demonstrated that while changes in lignin content in AHP-delignified biomass could be clearly correlated to improved response to hydrolysis, compositional changes alone in AFEX-pretreated biomass could not explain differences in hydrolysis yields. We determined the water retention value, which characterizes the association of water with the cell wall of the pretreated biomass, can be used to predict hydrolysis yields for all pretreated biomass within this study.


Assuntos
Biomassa , Poaceae , Hidrólise , Lignina , Água , Zea mays
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