Suatu Tinjauan Tentang Jenis-jenis Dan Penyebab Miskonsepsi Fisika

Miskonsepsi adalah kesalahanpemahaman dalam menghubungkan suatu konsep dengan konsep-konsep yang lain, antara konsep yang baru dengan konsep yang sudah ada dalam pikiran siswa, sehingga terbentuk konsep yang salah dan bertentangan dengan konsepsi para ahli Fisika. Miskonsepsi fisika ada lima macam, yaitu: (a) pemahaman konsep awal (preconceived notions); (b) keyakinan tidak ilmiah (nonscientific beliefs); (c) pemahaman konseptual salah (conceptual misunderstandings); (d) miskonsepsi bahasa daerah (Vernacular misconceptions); dan (e) miskonsepsi berdasarkan fakta (factual misconceptions). Penyebab miskonsepsi fisika ada lima bahagian, yaitu siswa (pengetahuan awal atau prakonsepsi/prior knowledge, pemikiran asosiatif siswa, pemikiran humanistik, reasoning yang tidak lengkap/salah, intuisi yang salah, tahap perkembangan kognitif siswa, kemampuan siswa, dan minat siswa), guru, bahan ajar atau literatur, konteks dan metode mengajar

Parabacteroides distasonis:intriguing aerotolerant gut anaerobe with emerging antimicrobial resistance and pathogenic and probiotic roles in human health

Parabacteroides distasonis is the type strain for the genus Parabacteroides, a group of gram-negative anaerobic bacteria that commonly colonize the gastrointestinal tract of numerous species. First isolated in the 1930s from a clinical specimen as Bacteroides distasonis, the strain was re-classified to form the new genus Parabacteroides in 2006. Currently, the genus consists of 15 species, 10 of which are listed as 'validly named' (P. acidifaciens, P. chartae, P. chinchillae, P. chongii, P. distasonis, P. faecis, P. goldsteinii, P. gordonii, P. johnsonii, and P. merdae) and 5 'not validly named' (P. bouchesdurhonensis, P. massiliensis, P. pacaensis, P. provencensis, and P. timonensis) by the List of Prokaryotic names with Standing in Nomenclature. The Parabacteroides genus has been associated with reports of both beneficial and pathogenic effects in human health. Herein, we review the literature on the history, ecology, diseases, antimicrobial resistance, and genetics of this bacterium, illustrating the effects of P. distasonis on human and animal health

Mild Coronavirus Disease 2019 (COVID-19) Is Marked by Systemic Oxidative Stress:A Pilot Study

Oxidative stress has been implicated to play a critical role in the pathophysiology of coronavirus disease 2019 (COVID-19) and may therefore be considered as a relevant therapeutic target. Serum free thiols (R-SH, sulfhydryl groups) comprise a robust marker of systemic oxidative stress, since they are readily oxidized by reactive oxygen species (ROS). In this study, serum free thiol concentrations were measured in hospitalized and non-hospitalized patients with COVID-19 and healthy controls and their associations with relevant clinical parameters were examined. Serum free thiol concentrations were measured colorimetrically (Ellman’s method) in 29 non-hospitalized COVID-19 subjects and 30 age-, sex-, and body-mass index (BMI)-matched healthy controls and analyzed for associations with clinical and biochemical disease parameters. Additional free thiol measurements were performed on seven serum samples from COVID-19 subjects who required hospitalization to examine their correlation with disease severity. Non-hospitalized subjects with COVID-19 had significantly lower concentrations of serum free thiols compared to healthy controls (p = 0.014), indicating oxidative stress. Serum free thiols were positively associated with albumin (St. β = 0.710, p < 0.001) and inversely associated with CRP (St. β = −0.434, p = 0.027), and showed significant discriminative ability to differentiate subjects with COVID-19 from healthy controls (AUC = 0.69, p = 0.011), which was slightly higher than the discriminative performance of CRP concentrations regarding COVID-19 diagnosis (AUC = 0.66, p = 0.042). This study concludes that systemic oxidative stress is increased in patients with COVID-19 compared with healthy controls. This opens an avenue of treatment options since free thiols are amenable to therapeutic modulation

Oral Biofilm Architecture on Natural Teeth

Periodontitis and caries are infectious diseases of the oral cavity in which oral biofilms play a causative role. Moreover, oral biofilms are widely studied as model systems for bacterial adhesion, biofilm development, and biofilm resistance to antibiotics, due to their widespread presence and accessibility. Despite descriptions of initial plaque formation on the tooth surface, studies on mature plaque and plaque structure below the gum are limited to landmark studies from the 1970s, without appreciating the breadth of microbial diversity in the plaque. We used fluorescent in situ hybridization to localize in vivo the most abundant species from different phyla and species associated with periodontitis on seven embedded teeth obtained from four different subjects. The data showed convincingly the dominance of Actinomyces sp., Tannerella forsythia, Fusobacterium nucleatum, Spirochaetes, and Synergistetes in subgingival plaque. The latter proved to be new with a possibly important role in host-pathogen interaction due to its localization in close proximity to immune cells. The present study identified for the first time in vivo that Lactobacillus sp. are the central cells of bacterial aggregates in subgingival plaque, and that Streptococcus sp. and the yeast Candida albicans form corncob structures in supragingival plaque. Finally, periodontal pathogens colonize already formed biofilms and form microcolonies therein. These in vivo observations on oral biofilms provide a clear vision on biofilm architecture and the spatial distribution of predominant species

Identifying Where REDD+ Financially Out Competes Oil Palm in Floodplain Landscapes Using a Fine-Scale Approach

Reducing Emissions from Deforestation and forest Degradation (REDD+) aims to avoid forest conversion to alternative land-uses through financial incentives. Oil-palm has high opportunity costs, which according to current literature questions the financial competitiveness of REDD+ in tropical lowlands. To understand this more, we undertook regional finescale and coarse-scale analyses (through carbon mapping and economic modelling) to assess the financial viability of REDD+ in safeguarding unprotected forest (30,173 ha) in the Lower Kinabatangan floodplain in Malaysian Borneo. Results estimate 4.7 million metric tons of carbon (MgC) in unprotected forest, with 64% allocated for oil-palm cultivations. Through fine-scale mapping and carbon accounting, we demonstrated that REDD+ can outcompete oil-palm in regions with low suitability, with low carbon prices and low carbon stock. In areas with medium oil-palm suitability, REDD+ could outcompete oil palm in areas with: very high carbon and lower carbon price; medium carbon price and average carbon stock; or, low carbon stock and high carbon price. Areas with high oil palm suitability, REDD + could only outcompete with higher carbon price and higher carbon stock. In the coarse-scale model, oil-palm outcompeted REDD+ in all cases. For the fine-scale models at the landscape level, low carbon offset prices (US $3 MgCO2e) would enable REDD+ to outcompete oil-palm in 55$27 million to secure these areas for 25 years. Higher carbon offset price (US $30 MgCO2e) would increase the competitiveness of REDD+ within the landscape but would still only capture between 69$380–416 million in carbon financing. REDD+ has been identified as a strategy to mitigate climate change by many countries (including Malaysia). Although REDD+ in certain scenarios cannot outcompete oil palm, this research contributes to the global REDD+ debate by: highlighting REDD+ competitiveness in tropical floodplain landscapes; and, providing a robust approach for identifying and targeting limited REDD+ funds

Ultrasound- assisted extraction propolis and its kinetic study

In current times, there has been a growing attention in the consumption of functional food such as propolis due to the abundant of available bioactive compounds such as polyphenols. There are several health properties of propolis reported on having a huge spectrum of biological properties including anti- inflammatory, antioxidant, anticancer and antimicrobial. Maceration is known for its longer extraction time issue. Ultrasonic- assisted extraction is seen as an alternative to solve this problem. This study focused on indicating the factors influencing solid liquid ultrasonic- assisted extraction of total polyphenols content (TPC) from propolis using ethanol as solvent. The effects of three main factors; temperature (25°C, 35°C, 45°C, 55°C, 65°C), reaction time (5, 10, 15, 20, 25 minutes) and concentration of ethanol (50:50, 60:40, 70:30, 80:20, 90:10) (v/v) were studied to achieve maximum total phenolic content. The optimum conditions for ultrasonic- assisted extraction of phenolic content from propolis are with 70% ethanol, at 65°C for 25 mins. From the experimental data of kinetics study, the ultrasonic extraction of phenolic compounds from propolis is the second- order kinetic model and the extraction constant (k2) was 2.8998 g mg-1 min-1

The Effects of Different Ethanol Concentration on Total Phenolic and Total Flavonoid Content In Malaysian Propolis

As compared to honey, propolis was considered 'less explored' in active compounds characterization study. The abundance of phytochemicals in propolis contributes to various medicinal properties such as antimicrobial, anticancer, wound healing and antioxidative. The most common antioxidant groups found in propolis are phenolic acids and flavonoids. Hence, in the current study, we investigated the relationship between different ethanol concentrations on the total phenolic content (TPC) and total flavonoid content (TFC) extracted from propolis. Crude propolis was crushed and sieved before ultrasonic extractions using different ethanol concentrations (20, 50, 80%). The determination of total phenolic content was obtained from the reaction of propolis extract with Folin- Ciocalteu reagent. The result of the total phenolic content was obtained from gallic acid calibration curve and represented in gallic acid equivalent (GAE). Meanwhile, quantification of total flavonoid content was obtained from the reaction of the extract with methanolic solution of aluminum chloride (AlCl3). The result of the total flavonoid content of the propolis was acquired from quercetin calibration curve and represented in quercetin equivalent (QE). The highest TPC and TFC were recorded at 80% ethanol being 8.898 mg GAE/ml and 0.034 mg QE/ml respectively. From the experimental data, it is shown that TPC and TFC are directly propotional to ethanol concentration

Optimization of total phenolic compounds extracted from propolis by ultrasound- assisted extraction

The presence of phenolics in propolis contributes to several health benefits such as anti-microbial, antioxidant, anticancer, and anti-inflammatory properties. In this study, total phenolic compounds from propolis were extracted with the aid of sonication. The parameters screening was done by one factor at time (OFAT) which involved types of solvent, ethanol concentration, extraction temperature and extraction time. The highest total phenolic content obtained was at 80%, 25 minutes, 65 °C for ethanol concentration, extraction time and extraction temperature respectively. Optimization of the experimental parameters was done by applying response surface methodology (RSM). The best potential variation of the factors (X); ethanol concentration (X1), extraction temperature (X2) and extraction time (X3) was generated. The optimum conditions of the variables were 80% (X1), 25 min (X2) and 60 °C (X3). Under this setting, the phenolic content from the experimental work obtained was 0.1007 mg GAE/g of propolis, which complemented the predicted value

Assessment of the microbiota of a mixed infection of the tongue using phenotypic and genotypic methods simultaneously and a review of the literature

We assessed the microbiota of a tongue abscess in which twelve different aerobic and anaerobic bacteria were identified using fluorescent in situ hybridisation (FISH), sequencing of the 16S rRNA gene and phenotypic methods. By applying the 16S rRNA based probes directly on the clinical material, a quick insight of the bacteria present was obtained and the species which were not cultured but present in the abscess were identified. (C) 2011 Elsevier Ltd. All rights reserved