Pretreatment Protocol Research Articles

Comparsion of two different dentin pretreatment protocols on bond strength of glass fiber post using self-etch adhesive

Aim and objectives Aim: Is to evaluate the two different natural crosslinking agents citric acid and grape seed extract. Objective: To know the difference between the two agents on bond strength of fiber post on to root dentin using self-etch adhesive. Materials and Methods 1. 30 Single rooted maxillary anterior teeth with similar root segments and fully developed apices were selected. 2. Root canal treatment is performed and post space preparation is done using #2 peeso reamers and irrigated with 2.5% NaOCl and 17% of EDTA and dried with paper points and then divided in to 3 groups according to pretreatment used. Group 1: No pretreatment, only conventional self-etching & bonding. (Control Group). Group 2: Pretreatment with 10% citric acid for 5 Minutes. Group 3: Pretreatment with 6.25% Grape seed extract for 5 Minutes. 3. The post space treated with self-etch adhesive and fiber post is bonded using flowable composite 4. Bond strength evaluation is done by transversely sectioning the roots of each group of 1.0 MM, thickness and 3 sections were obtained and embedded in acrylic resin block. Micro push-out bond strength was measured using universal testing machine and SEM analysis is done to classify the facture pattern.

Novel Pharmaceutical Strategy for Selective Abrogation of TSP1-Induced Vascular Dysfunction by Decoy Recombinant CD47 Soluble Receptor in Prophylaxis and Treatment Models.

Elevated thrombospondin 1 (TSP1) is a prevalent factor, via cognate receptor CD47, in the pathogenesis of cardiovascular conditions, including ischemia-reperfusion injury (IRI) and pulmonary arterial hypertension (PAH). Moreover, TSP1/CD47 interaction has been found to be associated with platelet hyperaggregability and impaired nitric oxide response, exacerbating progression in IRI and PAH. Pathological TSP1 in circulation arises as a target of our novel therapeutic approach. Our “proof-of-concept” pharmacological strategy relies on recombinant human CD47 peptide (rh-CD47p) as a decoy receptor protein (DRP) to specifically bind TSP1 and neutralize TSP1-impaired vasorelaxation, strongly implicated in IRI and PAH. The binding of rh-CD47p and TSP1 was first verified as the primary mechanism via Western blotting and further quantified with modified ELISA, which also revealed a linear molar dose-dependent interaction. Ex vivo, pretreatment protocol with rh-CD47p (rh-CD47p added prior to TSP1 incubation) demonstrated a prophylactic effect against TSP1-impairment of endothelium-dependent vasodilation. Post-treatment set-up (TSP1 incubation prior to rh-CD47p addition), mimicking pre-existing excessive TSP1 in PAH, reversed TSP1-inhibited vasodilation back to control level. Dose titration identified an effective molar dose range (approx. ≥1:3 of tTSP1:rh-CD47p) for prevention of/recovery from TSP1-induced vascular dysfunction. Our results indicate the great potential for proposed novel decoy rh-CD47p-therapy to abrogate TSP1-associated cardiovascular complications, such as PAH.

Fast Screening of Dithiocarbamate, Chloronicotinyl and Organophosphate Pesticides By Raman Spectroelectrochemistry Based on EC-SERS Effect

Electrochemical surface-enhanced Raman scattering (EC-SERS) effect is an outstanding procedure that ensures the enhancement of Raman signal by the electrochemical activation of the electrode surface. In that way, activation of metallic screen-printed electrodes (SPEs) by electrochemical routes leads to the generation of reproducible nanostructures with excellent SERS properties [1,2] and opens new gates for analytical applications.In this work, detection of thiram, imidacloprid and chlorpyrifos pesticides is achieved by the development of a new procedure. This methodology offers a quick and easy protocol which consists of three steps: (1) preconcentration of the sample, (2) electrochemical activation of SPE and (3) Raman detection of pesticides (Figure 1).Figure 1. Raman spectrum of thiram obtained following the proposed procedure.Analysis of tap water samples provides suitable results that demonstrate the capabilities of the proposed method. In that way, Raman spectroelectrochemistry based on EC-SERS effect avoids the complicated instrumentation, tedious pretreatment protocols or time-consuming measurement procedures used in other methods, and offers an interesting alternative in fields as environmental and food safety.

Applying fluorescence in situ hybridization to aquatic systems with cyanobacteria blooms: Autofluorescence suppression and high‐throughput image analysis

AbstractCyanobacterial Harmful Algal Blooms (CyanoHABs) are expanding geographically in both fresh and marine water bodies due to coastal eutrophication and global climate change and are restructuring the microbial ecology of these systems. Cyanobacterial autofluorescence can pose a significant impediment to accurately identifying prokaryotic taxonomic groups in environmental samples using fluorescence in situ hybridization (FISH). This can hinder our ability to accurately quantify, and therefore fully understand ecological changes. As abundances of FISH target cells and autofluorescent cells can often be of the same the order of magnitude, simply subtracting average autofluorescent cell concentrations—determined from enumerating unhybridized samples—yields apparent concentrations of target cells with unacceptably large analytical uncertainty. Here we present a CuSO4/EtOH chemical pretreatment protocol that significantly reduces undesirable autofluorescence in hybridized environmental samples. We apply a novel data filtration routine to FISH images that efficiently removes residual autofluorescent cells from final cell counts. We then subject images to an automated image analysis routine that accurately enumerates probe‐positive cells. This method is inexpensive and easy to implement as part of a routine FISH workflow. By applying this method to cyanobacteria rich samples, we can better understand how microbial community changes are contributing to globally changing biogeochemical cycles.

Bond strength of demineralized dentin after synthesized collagen/hydroxyapatite nanocomposite application

Treatment the deeper and remineralizable carious zone (DRCZ) in dentin with various remineralizing methods, either with classic top-down or biomimetic bottom-up remineralization approaches, has remained a constant main issue to enhance dentin substrate bonding quality. The concern of remineralizing the remaining, partially demineralized and physiologically re-mineralizable collagen fibrils was the optimum target. However, applying already mineralized type I collage fibrils which have the ability to chemically cross-link with remaining collagen and minerals did not gain much interest. Synthesis of collagen/hydroxyapatite (Col/Hap) nanocomposite was done with self-assembling Hap in situ onto Col fibrils with different % (70/30, 50/50, 30/70% of Col/Hap, respectively). Micro-tensile bond strength (μTBS) was evaluated after pre-treatment of artificially demineralized dentin with these suggested protocols [nanocomposite together with grape seed extract (GSE; 6.5%) cross-linker for two periods, 10min and 1 h] then applying self-adhesive bonding system. Applied Col/Hap (30/70%) together with GSE (6.5%) gave the significantly highest μTBS (25.04 ± 5.47 and 25.53 ± 7.64 MPa, for 10min and 1 h application times, respectively). After thermocycling for 10,000 cycles at 5 and 55 °C, μTBS for all protocols and both application times substantially decreased especially for the two control groups. Using the suggested dentin pre-treatment protocols, in chair-side, may possibly enhance the bond strength to DRCZ and its durability.

Rapid exposure monitoring of six bisphenols and diethylstilbestrol in human urine using fabric phase sorptive extraction followed by high performance liquid chromatography – photodiode array analysis

A novel fabric phase sorptive extraction protocol is developed for rapid exposure monitoring of six bisphenol analogues, including bisphenol A, bisphenol S, bisphenol F, bisphenol E, bisphenol B, bisphenol C, and diethylstilbestrol (DES) from human urine prior to high-performance liquid chromatography-photodiode array analysis.FPSE sample pretreatment protocol ensures the harmonization of the proposed method with the principles of Green Analytical Chemistry (GAC). Among eighteen evaluated FPSE membranes, sol-gel poly (ethylene glycol) (PEG) coated cellulose FPSE membrane resulted in the most efficient extraction. This polar FPSE membrane effectively exploits a number of advantageous features inherent to FPSE including sponge-like porous architecture of the sol-gel sorbent coating, favorable surface chemistry, flexibility and built-in permeability of cellulose fabric substrate, high primary contact surface area for rapid sorbent-analyte interaction, expanded pH, solvent and thermal stability as well as reusability of the FPSE membrane.Optimization was centered on the evaluation of critical parameters, namely the size of the FPSE membrane, the elution solvent mixture, the volume of the sample, the extraction time, the elution time, the kind of the external agitation mechanical stimulus, the ionic strength and the pH of the sample. The chromatographic separation was achieved on a Spherisorb C18 column and a gradient elution program with mobile phase consisted of 0.05 ammonium acetate solution and acetonitrile. The total analysis time was 17.4 min. The developed method was validated in terms of linearity, sensitivity, selectivity, precision, accuracy, stability, and ruggedness. The limits of detection and quantification varied from 0.26–0.62 ng/mL and 0.8–1.9 ng/mL, respectively. The relative recoveries were calculated between 90.6 and 108.8%, while the RSD values were <10% in all cases. The effectiveness of the proposed method was confirmed by its successful implementation in the bioanalysis of real urine samples.

Membrane cleaning and pretreatments in membrane distillation – a review

Membrane distillation (MD) is an emerging thermal-based membrane technology that has the capacity to treat a wide range of feed waters, including high salinity brines and wastewater. Compared with pressure-driven processes, MD has the following advantages: low electrical energy consumption, complete removal of non-volatile solutes and ambient operating pressures. On the other hand, membrane fouling and pore wetting remain a challenge holding back its wider industrial implementation. To manage this issue, effective pretreatment and cleaning strategies are essential, as with other membrane processes. Despite the importance of these aspects for achieving a stable and reliable water treatment process, far too little attention has been paid to them in the MD literature. Evidence of this is that a comprehensive review on both membrane cleaning and pretreatment in MD is still lacking, despite the large and growing number of publications related to the technology. In this work, we first provide an overview of the three main types of fouling present in MD: inorganic, organic and biological fouling. After this we review, in detail, the use of pretreatment protocols in a range of MD applications, highlighting their efficacy in preventing fouling and ensuring stable performance. Next, we review the use of state-of-the-art chemical and physical cleaning strategies and discuss the development of ‘self-cleaning’ membranes that are superhydrophobic or omniphobic. Finally, future research directions are suggested, with the aim of helping researchers working in this field to develop membrane distillation technology towards wider commercial implementation.

Developing an analytical method for free amino acids in atmospheric precipitation using gas chromatography coupled with mass spectrometry

Amino acids in rain samples offer important information on their origin and roles in biogeochemical cycling. This paper describes the development and validation of an alternative analytical procedure for amino acids in atmospheric precipitation using gas chromatography coupled with mass spectrometry (GC–MS). The method detection limits (MDLs) of these amino acids ranged from 1.46 ng L−1 (Proline) to 135 ng L−1 (Arginine), which were much lower than previous methods like high-performance liquid chromatography (HPLC) and comparable to those with liquid chromatography-tandem mass spectrometry (LC-MS/MS). None of the target analytes were detected in blank samples, which was attributed to the optimized pretreatment protocol we adopted. We conclude that the GC–MS based technique developed in this study possesses advantage due to low detection limits. We further demonstrate the applicability of this method by analyzing rain samples from the background atmosphere of the Tibetan Plateau (TP). Similar relative abundances of amino acids were found in the TP rains, marine rains and Arctic ice. The correlations between FAAs and water- soluble ions in the Tibetan Plateau rainwaters showed that the FAAs were most likely originated from biomass burning. Given the similarity of snow and rain samples, our method also provides potential for the future analysis of amino acids in glacier ice cores.

Identification of peroxiredoxin 6 as a potential lung-adenocarcinoma biomarker for predicting chemotherapy response by proteomic analysis.

The prognosis of lung cancer remains poor due to the limited biomarker selection for treating patients with optimal chemotherapy. The aim of this study is to discover and identify new biomarkers with the value of predicting chemotherapy responses in a lung adenocarcinoma (AD) specimen. In this study, six pairs of pre-treatment fresh primary lung AD-cancer tumors with varied chemotherapy responses were used to discover new biomarkers by two-dimensional difference gel electrophoresis (2D DIGE). Among the matched protein spots, 19 were up-regulated and 18 were down-regulated in chemo-sensitive tumors versus chemo-resistant tissues. These differentially expressed proteins could be divided into five classes: redox regulation protein, the cytoskeletal protein, cell metabolism enzymes or proteins, apoptosis, signal transduction mediated molecules, and other functional proteins. Proteins of interest, including PRDX2, PRDX6, and Gelsolin, were differentially expressed in chemo-sensitive tumors versus chemo-resistant tissues and these observations were validated by immunohistochemistry in 92 formalin-fixed and paraffin-embedded (FFPE) specimens. Our results demonstrated that PRDX6 protein expression was closely related to tumor response (cc2 = 5.57, P < 0.05), whereas no relationship of PRDX2 and Gelsolin were obtained with tumor response (cc2 = 0.51 P > 0.05, cc2 = 0.41 P > 0.05). This tissue proteomics study provides evidence that PRDX6 may be regarded as a predictive biomarker for poor chemotherapy response, which can be helpful in guiding pretreatment protocols.

Effects of different branched-chain amino acids supplementation protocols on the inflammatory response of LPS-stimulated RAW 264.7 macrophages.

Although branched-chain amino acids (BCAA) are commonly used as a strategy to recover nutritional status of critically ill patients, recent findings on their role as immunonutrients have been associated with unfavorable outcomes, especially in obese patients. The present study aimed to explore the effects of different BCAA supplementation protocols in the inflammatory response of LPS-stimulated RAW 264.7 macrophages. Cell cultures were divided into five groups, with and without BCAA supplementation, (2mmol/L of each amino acid). Then, cell cultures followed three different treatment protocols, consisting of a pretreatment (PT), an acute treatment (AT), and a chronic treatment (CT) with BCAA and LPS stimulation (1µg/mL). Cell viability was analyzed by MTT assay, NO production was assessed by the Griess reaction and IL-6, IL-10, TNF-α and PGE2 synthesis, was evaluated by ELISA. BCAA significantly increased cell viability in AT and CT protocols, and NO and IL-10 synthesis in all treatment protocols. IL-6 synthesis was only increased in PT and CT protocols. TNF-α and PGE2 synthesis were not altered in any of the protocols and groups. BCAA supplementation was able to increase both pro and anti-inflammatory mediators synthesis by RAW 264.7 macrophages, which was influenced by the protocol applied. Moreover, these parameters were significantly increased by isoleucine supplementation, highlighting a potential research field for future studies.

Renal function impairment in cervical cancer patients treated with cisplatin-based chemoradiation: A review of medical records in a Zimbabwean outpatient department.

There is a potential increase in risk of renal function impairment among patients with invasive cervical cancer (ICC) who are HIV-positive and treated with cisplatin-based concurrent chemoradiation (CCRT). This concern is due to overlapping nephrotoxicity of the drugs, and nephropathy from the diseases themselves. There is limited literature available for the short-term renal outcomes for HIV-positive patients with ICC during routine clinical management. This study aimed to assess if HIV-infection increased the risk of renal impairment in ICC patients treated with CCRT, and explore the respective risk factors. This was a retrospective review of records of ICC patients treated with at least one cycle of weekly cisplatin during CCRT at the Parirenyatwa Radiotherapy Center from January 2017-December 2018. The RIFLE criteria were used to classify renal impairment. Analyses were performed with Fisher's Exact tests, Wilcoxon rank sum tests. Odds ratios (OR) were generated using logistic regression. All statistical tests were 2-sided at a 5% level of significance. Seventy-two eligible patients were identified, 32 (44.44%) were HIV-positive. HIV-positive patients were younger (p = 0.002), had lower albumin levels (p = 0.014) and received lower cisplatin doses (p = 0.044). The mean percent reduction in estimated glomerular filtration rate (eGFR) from baseline was -19% (95% CI: -25.9% to -13.2%) for all patients. Thirty-one (43.1%) patients experienced renal impairment, 50% and 37.5% of HIV-positive and -negative patients respectively (p = 0.287). HIV-infection was associated with an adjusted OR of 1.16 (95% CI 0.35-3.43, p = 0.769). Baseline eGFR< 60ml/min was the only independent predictor of renal impairment, OR 0.25 (95% CI: 0.07-0.85). Baseline eGFR<60ml/min was also associated with receipt of lower cisplatin doses (p = 0.044). HIV-infection was not associated with elevated risk of renal impairment. Patients with an eGFR<60ml/min appear to be managed more cautiously reducing their risk for renal impairment during cisplatin therapy. The high prevalence of renal impairment in this population suggests the need for optimization of pre-treatment protocols.

Comparative Study of Eleven Mechanical Pretreatment Protocols for Cryptosporidium parvum DNA Extraction from Stool Samples.

Nowadays, many commercial kits allow the polymerase chain reaction (PCR) detection of Cryptosporidium deoxyribonucleic acid (DNA) in stool samples, the efficiency of which relies on the extraction method used. Mechanical pretreatment of the stools using grinding beads has been reported to greatly improve this extraction step. However, optimization of this key step remains to be carried out. Indeed, many parameters could influence the pretreatment performances, among which the modulation of the speed and duration of the grinding step, in addition to the physicochemical features of the grinding beads, have never been evaluated to date. In this study, eleven commercial mechanical pretreatment matrixes (Lysis matrix tubes®, MP Biomedical, Irvine, CA, USA) composed of beads with different sizes, shapes, and molecular compositions, were evaluated for their performances in improving Cryptosporidium parvum oocyst DNA extraction before amplification by using our routinely used real-time PCR method. As expected, the eleven commercial mechanical pretreatment matrixes showed varying performances depending on the composition, size, and shape. All in all, the best performances were obtained when using the Lysing matrix, including ceramic beads with a median size (diameter of 1.4 mm).

LAC-UFF STATUS REPORT: CURRENT PROTOCOLS AND RECENT DEVELOPMENTS

ABSTRACTThe Radiocarbon Laboratory of the Fluminense Federal University was installed in 2009, and its NEC Single Stage Accelerator Mass Spectrometry system has been operational since 2012. As the first14C-AMS facility in Latin America, the LAC-UFF became a reference center for radiocarbon (14C) dating in Brazil. Over the years we have implemented pretreatment protocols for several kinds of materials, such as cellulose, soil, bone, and biofuels. In the present paper we describe our current protocols for the preparation of these types of samples. Moreover, after 10 years of operation, with the aim of expanding the range of materials we are able to analyze, we report the results of several tests to improve accuracy, precision and background levels. For example, here we discuss how isotopic fractionation during the graphitization and measurement steps has been controlled. Concerning results interpretation, our research group has been using OxCal chronological models to analyze different contexts such as stromatolite growth, tree rings, soil deposition and marine reservoir effect (MRE) determination.

Precious Metal-Free LaMnO3 Perovskite Catalyst with an Optimized Nanostructure for Aerobic C-H Bond Activation Reactions: Alkylarene Oxidation and Naphthol Dimerization.

In this article, we describe the development of a new aerobic C-H oxidation methodology catalyzed by a precious metal-free LaMnO3 perovskite catalyst. Molecular oxygen is used as the sole oxidant in this approach, obviating the need for other expensive and/or environmentally hazardous stoichiometric oxidants. The electronic and structural properties of the LaMnO3 catalysts were systematically optimized, and a reductive pretreatment protocol was proved to be essential for acquiring the observed high catalytic activities. It is demonstrated that this newly developed method was extremely effective for the oxidation of alkylarenes to ketones as well as for the oxidative dimerization of 2-naphthol to 1,1-binaphthyl-2,2-diol (BINOL), a particularly important scaffold for asymmetric catalysis. Detailed spectroscopic and mechanistic studies provided valuable insights into the structural aspects of the active catalyst and the reaction mechanism.

Glicina e as suas aplicações na medicina dentária: uma revisão narrativa

Introduction: There are several minimally invasive treatments and sensitive clinical protocols which lead to the need to find an innovative alternative with different substances. Glycine, a non-essential amino acid with a simple structure and an important constituent in the extracellular structure of proteins such as collagen and elastin, has been used and tested in diverse dental medicine applications in the form of abrasive powder particles. Despite the mechanisms of action not being yet fully understood, it is believed to have anti-inflammatory therapeutic effects as well as helping in regulating the immune functions and synthesis of cytokines. Glycine is odorless, colorless and highly soluble in water. Objectives: To present the different glycine powder applications in dental medicine. Results: Different studies have been made to compare the glycine action with the use of various manual, rotary and polishing instruments, and with clinical protocols such as acid etching and pretreatment of the dentin structure. Glycine powder presents a reduced abrasive action, producing less damage to the teeth and gum surfaces. Its efficacy was observed in the removal of supra and subgingival biofilm, with reduced injury of the gingival structure when compared to the use of the sodium bicarbonate jet, root scraping and scaling. It achieved an excellent polishing and teeth surface smoothness, thus reducing the adhesion and maturation of the bacterial microflora. Conclusions: Glycine is nowadays regarded as an innovative substance in the world of dentistry and has been applied in the periodontics, polishing of dental surfaces, restorative material and in the pre-treatment protocol of dentin. Despite the good results obtained, further investigation is needed to validate these features and advantages.

Bone need not remain an elephant in the room for radiocarbon dating.

Radiocarbon (14C) analysis of skeletal remains by accelerator mass spectrometry is an essential tool in multiple branches of science. However, bone 14C dating results can be inconsistent and not comparable due to disparate laboratory pretreatment protocols that remove contamination. And, pretreatments are rarely discussed or reported by end-users, making it an ‘elephant in the room’ for Quaternary scientists. Through a questionnaire survey, I quantified consensus on the reliability of collagen pretreatments for 14C dating across 132 experts (25 countries). I discovered that while more than 95% of the audience was wary of contamination and would avoid gelatinization alone (minimum pretreatment used by most 14C facilities), 52% asked laboratories to choose the pretreatment method for them, and 58% could not rank the reliability of at least one pretreatment. Ultrafiltration was highly popular, and purification by XAD resins seemed restricted to American researchers. Isolating and dating the amino acid hydroxyproline was perceived as the most reliable pretreatment, but is expensive, time-consuming and not widely available. Solid evidence supports that only molecular-level dating accommodates all known bone contaminants and guarantees complete removal of humic and fulvic acids and conservation substances, with three key areas of progress: (i) innovation and more funded research is required to develop affordable analytical chemistry that can handle low-mass samples of collagen amino acids, (ii) a certification agency overseeing dating-quality control is needed to enhance methodological reproducibility and dating accuracy among laboratories, and (iii) more cross-disciplinary work with better 14C reporting etiquette will promote the integration of 14C dating across disciplines. Those developments could conclude long-standing debates based on low-accuracy data used to build chronologies for animal domestications, human/megafauna extirpations and migrations, archaeology, palaeoecology, palaeontology and palaeoclimate models.

Testing Various Pre-treatments on Artificially Waterlogged and Pitch-Contaminated Wood for Strontium Isotope Analyses

Strontium isotope ratios (87Sr/86Sr) are commonly used in archeological and forensic studies to assess if humans and fauna are local to the place they were found or not. This approach is largely unexplored for wooden artifacts recovered in archeological contexts, as wood – in the rare instances it does survive – is often poorly preserved. One of the most common ways wood is preserved is through the anoxic conditions found in waterlogged contexts. A more unusual form of preservation is through submergence in natural pitch. These depositional media contribute their own strontium values to the in vivo87Sr/86Sr wood values, which needs to be removed prior to analysis. Here we test several pre-treatment methods to remove potential strontium contamination from wood samples that were artificially immersed in seawater and pitch from Trinidad’s Pitch Lake. Water rinses and acid-leaching tests were carried out with hydrochloric acid and acetic acid to remove exogenous strontium from experimentally waterlogged wood. These tests removed large amounts of strontium from the samples and did not enable the recovery of the endogenous 87Sr/86Sr signal. For samples artificially immersed in pitch, the pre-treatments tested were based on radiocarbon dating procedures and carried out with and without the aqueous-based acid-base-acid (ABA) step. The use of organic solvents alone (methanol and toluene) removed exogenous strontium originating from the pitch. However, the ABA step eliminates large amounts of in vivo strontium from the samples. These tests show that 87Sr/86Sr values of wood are altered by the presence of pitch and water. With adequate pre-treatment using exclusively organic solvents, it may be possible to remove this contamination for samples immersed in pitch. However, the aqueous-based ABA pre-treatment should be avoided. The removal of contamination from waterlogged samples was unsuccessful with the current pre-treatment protocols and more research is needed. More importantly, and unexpectedly, 87Sr/86Sr values may extend outside of the mixing line between the wood’s endogenous strontium and the water. These results indicate the need for extreme caution when attempting to determine the provenance of waterlogged wood.

“Here we go again”: the inspection of collagen extraction protocols for 14C dating and palaeodietary analysis

ABSTRACT Archaeological bone collagen is highly useful for radiocarbon (14C) dating and palaeodietary reconstruction. However, collagen preservation and carbon contamination are essential considerations when extracting collagen, becoming especially crucial close to the limit of the method (50,000 years before present = BP). Strong progress has been achieved in the past two decades by 14C and stable isotopic laboratories in removing contamination from archaeological bones, but different pretreatment protocols have been proven to produce varying results. Here we compare three collagen extraction protocols used for palaeodietary studies and 14C dating, considering collagen yield, elemental and stable isotopic data, FTIR analysis, and 14C dates. We focus on the impact of ultrafiltration on the yield and quality of the extracted material. The results again underline the importance of rigorous decontamination methods to gain accurate 14C dates and demonstrate that different protocols have significant effects on the quality and yield of extracted collagen.

Efficient enzymatic hydrolysis of chitin into N-acetyl glucosamine using alkali as a recyclable pretreatment reagent

In this study, an alkali freeze–thaw pretreatment protocol was investigated to efficiently enhance enzymatic hydrolysis of chitin into GlcNAc at high concentrations.

Mechanical behavior and durability of coral aggregate concrete and bonding performance with fiber-reinforced polymer (FRP) bars: A critical review

Utilization of coral aggregates (CAs) for concrete production can effectively resolve the shortage of raw materials for construction in remote islands and reduce the energy consumption due to the shipping from the mainland. However, the porous nature of CAs and contained salt will affect the mechanical and durability performance of the concrete. This study aims to first summarize the characteristics of CAs and properties of coral aggregate concrete (CAC) and then propose future research needs based on the identified knowledge gaps. The previous studies indicate that the utilization of CAs in concrete can lead to significant strength loss and the elastic modulus of CAC is generally lower than that of ordinary concrete (OC). The workability of concrete at the fresh stage can also be reduced by the added porous CAs. To resolve these issues, the pre-treatment protocols were proposed to enhance the performance of CAC, including acid washing, surface coating, and utilization of alternative cementitious materials. However, the influence of CAs on the durability performance of concrete has not been fully understood, including drying shrinkage and carbonation resistance. The corrosion issue is also a serious threat to the durability performance of reinforced CAC. It is expected that using the non-corrosive fiber-reinforced polymer (FRP) bars can effectively resolve the corrosion issues, but the related investigations are quite limited. The research needs on the durability performance of CAC and the evaluation of FRP bars reinforced CAC are then proposed for further investigation. This study can serve as a solid base for future investigation on CAC and promote its application in ocean engineering. • The effects of coral aggregates on the properties of concrete are discussed. • Many effective measures to improve the performance of coral aggregate concrete are summarized. • The combination of fiber reinforced polymer bars and coral aggregate concrete is attractive.