Fortification of sulfited tannin from the bark of Acacia mangium with phenol–formaldehyde for use as plywood adhesive

The Acacia mangium tree contains 10% bark (v/v), of which about 20% are extractives. Extraction of this bark using a combination of water and sulfite medium can produce between 15% and 25% tannin materials (dry weight). In this work, several extraction conditions such as bark size, plantation site, extraction time and extraction medium were studied. The results showed that by using either hot water or a sulfite medium, a reasonable amount of tannin yield can be obtained. Bark size of less than 1-mm mesh size gave relatively high tannin yield irrespectively of the extraction medium used. Using a 600:100:2:0.5 (w/w) ratio of water:bark:sodium sulfite:sodium carbonate, and reacted at 75 °C for 3 h improved the tannin yield by at least 30%. The extracts were reasonably reactive towards formaldehyde as shown by their high Stiasny number; water extract, 60–70% and aqueous sulfite–carbonate extracts, 85–90%. The gluing results showed that the shear strength of the plywood can meet the requirements of the European Standards EN 314-1 and EN 314-2:1993. Incorporation of low molecular weight PF resin (10 parts) and PF (10 parts) improved the shear strength from 0.96 MPa to 1.43 MPa after a 72 h boiling test. This study showed that A. mangium tannin blended with commercial plywood phenol–formaldehyde resin, low molecular weight PF and paraformaldehyde as a cross-linker can be used to bond Kedondong (Canarium spp.) wood veneers suitable for both interior and exterior grade plywood

Acacia mangium tannin as formaldehyde scavenger for low molecular weight phenol-formaldehyde resin in bonding tropical plywood

One of the limitations in using low molecular weight phenol-formaldehyde (LmwPF) resin as a binder for wood-based panels is the amount of the free formaldehyde being emitted during soaking, pressing and sometimes during the earlier stage of application. Tannin from bark extracts is rich in phenolic compounds, and thus may be able to absorb this free formaldehyde and at the same time provide strength to the joint. In this study, tannin–phenol-formaldehyde adhesives were prepared by blending Acacia mangium bark extracts (40% solids) with low molecular weight phenol-formaldehyde (40% solids at 1:1 ratio). The tannin–LmwPF adhesive produced cured within 4 min at 130°C, reduced the free formaldehyde to level E1 of European norm EN-120. The 3-ply plywood had acceptable shear strength (>1.0 MPa) exceeding the minimum requirements of European norms EN-314-1 and EN-314-2:1993 for interior and exterior applications, respectively. The study has shown that Acacia mangium tannin can be used as formaldehyde scavenger in LmwPF resin without compromising the strength of the joints

In situ growth of redox-active iron-centered nanoparticles on graphene sheets for specific capacitance enhancement

AbstractA fast and facile approach is proposed to enhance the specific capacitance of N-Methyl-2-pyrrolidone (NMP)-exfoliated graphene. Redox-active nickel ferricyanide (NiFeCN) nanoparticles were grown on the surface of graphene sheets using a simple co-precipitation method. Apart from the synergetic effect of graphene as double layer capacitance and NiFeCN as pseudocapacitance in specific capacitance enhancement, the NiFeCN nanoparticles served as the spacer to prevent the graphene sheets agglomeration. The NiFeCN/graphene exhibited specific capacitance of 113.5Fg−1, which was 2 times higher than the NMP-exfoliated graphene (52Fg−1) and 6times higher than the pure NiFeCN (18Fg−1). The findings suggested the NiFeCN/graphene could be the potential candidate for supercapacitor electrode

AN EVALUATION OF THE POOLED LOLLI-METHOD RT-qPCR TESTING FOR COVID-19 SURVEILLANCE IN SINGAPORE

Background: Following the success of the Lolli-Method or Lolli-Test as a surveillance method in Germany, the Ministry of Health, Singapore investigated the feasibility of deploying the method as a rostered routine testing in vulnerable individuals such as children, nursing homes and frontline workers; and evaluated the sensitivity and ideal pooling ratio of the Lolli-Method.  Methods: The study was conducted in two phases – the first phase was to assess the operational feasibility of the Lolli-Method. It was held in conjunction with air sampling at a childcare centre with children ages 2 to 6 years old across 40 days. The second phase was to evaluate the sensitivity of the Lolli-Method with different pooling ratios and was conducted in collaboration with the National Centre for Infectious Diseases (NCID) where each pool was spiked with one Lolli swab from a COVID-positive patient. All patients enrolled in this study have their viral load cycle threshold (CT) levels assessed prior to admission via a mid-turbinate oropharyngeal (MTOP) polymerase chain reaction (PCR) swab.  Results: The sensitivity of the pooled Lolli-Test was similar to antigen rapid tests with 100% sensitivity (3/3) in a pooling ratio of 20:1 for patients with viral loads of cycle threshold (CT) levels below 20. For individuals with lower viral loads, the sensitivity of the Lolli-Test was 66.7% (2/3) in a pooling ratio of 20:1 and 100% (2/2) in a smaller pooling ratio of 15:1. The operational feasibility of the Lolli-Test was assessed to be high amongst study participants although students were noted to require some additional assistance from teachers.  Conclusion: The Lolli-Test is an effective surveillance method with adequate sensitivity to detect a COVID-19 infected individual in a pool of up to 20 albeit largely dependent on the viral load. Furthermore, the Lolli-Test also provides a less invasive alternative sample collection method for individuals who cannot tolerate or have contraindications for the regular nasal or oropharyngeal swabs such as young children. More studies should be done to assess the Lolli-Test’s true limit of detection and to evaluate the use of the Lolli-Method in infants and for other respiratory diseases such as influenza

Dual-functional single stranded deoxyribonucleic acid for graphene

This study reports a one-step process to produce single-stranded deoxyribonucleic acid (ssDNA) functionalized reduced graphene oxide (ssDNA/rGO). The ssDNA acts as a reducing agent for the reduction of GO into rGO and simultaneously performs functionalization onto rGO, which is confirmed by spectroscopic and microscopic analyses. Such reduction capability is not being observed in double-stranded DNA (dsDNA). The high charge density of ssDNA on rGO is investigated for its application in electrochemical supercapacitor, and it is revealed that the ssDNA/rGO exhibits a specific capacitance of 129 F g−1 with high stability (92%) up to 10,000 cycles. The findings open the gateway to develop a biomolecule-based energy storage system

Pseudocapacitive performance of phenothiazine functionalized graphene aerogel

This study utilizes light adsorbing molecule, phenothiazine (PTZ) to reduce graphene oxide (GO) and functionalize into PTZ-rGO aerogel (PTZ-rGO). The UV excited PTZ reduces GO via electron transfer while PTZ is simultaneously oxidized and functionalized onto rGO to produce PTZ-rGO aerogel. The optimum incorporation of PTZ on rGO sheets renders good electrochemical active surface area of 495.71 m2 g−1 and enhances the diffusion behavior up to 41.92%. This pseudocapacitive effect and the excellent surface property provide promising charge storage results of 235.5 F g−1 at 0.5 A g−1. Furthermore, the stable charge-discharge cycles with 92% capacitance retention after 10,000 cycles render it an excellent electrode material for supercapacitor fabrication

Structural and Functional Analysis of Disease-Linked p97 ATPase Mutant Complexes

IBMPFD/ALS is a genetic disorder caused by a single amino acid mutation on the p97 ATPase, promoting ATPase activity and cofactor dysregulation. The disease mechanism underlying p97 ATPase malfunction remains unclear. To understand how the mutation alters the ATPase regulation, we assembled a full-length p97^(R155H) with its p47 cofactor and first visualized their structures using single-particle cryo-EM. More than one-third of the population was the dodecameric form. Nucleotide presence dissociates the dodecamer into two hexamers for its highly elevated function. The N-domains of the p97^(R155H) mutant all show up configurations in ADP- or ATPγS-bound states. Our functional and structural analyses showed that the p47 binding is likely to impact the p97^(R155H) ATPase activities via changing the conformations of arginine fingers. These functional and structural analyses underline the ATPase dysregulation with the miscommunication between the functional modules of the p97^(R155H)

Recurrent Fusion Genes in Gastric Cancer: CLDN18-ARHGAP26 Induces Loss of Epithelial Integrity.

Genome rearrangements, a hallmark of cancer, can result in gene fusions with oncogenic properties. Using DNA paired-end-tag (DNA-PET) whole-genome sequencing, we analyzed 15 gastric cancers (GCs) from Southeast Asians. Rearrangements were enriched in open chromatin and shaped by chromatin structure. We identified seven rearrangement hot spots and 136 gene fusions. In three out of 100 GC cases, we found recurrent fusions between CLDN18, a tight junction gene, and ARHGAP26, a gene encoding a RHOA inhibitor. Epithelial cell lines expressing CLDN18-ARHGAP26 displayed a dramatic loss of epithelial phenotype and long protrusions indicative of epithelial-mesenchymal transition (EMT). Fusion-positive cell lines showed impaired barrier properties, reduced cell-cell and cell-extracellular matrix adhesion, retarded wound healing, and inhibition of RHOA. Gain of invasion was seen in cancer cell lines expressing the fusion. Thus, CLDN18-ARHGAP26 mediates epithelial disintegration, possibly leading to stomach H(+) leakage, and the fusion might contribute to invasiveness once a cell is transformed. Cell Rep 2015 Jul 14; 12(2):272-285

Discovery of very-high-energy emission from RGB J2243+203 and derivation of its redshift upper limit

Very-high-energy (VHE; $>$ 100 GeV) gamma-ray emission from the blazar RGB J2243+203 was discovered with the VERITAS Cherenkov telescope array, during the period between 21 and 24 December 2014. The VERITAS energy spectrum from this source can be fit by a power law with a photon index of $4.6 \pm 0.5$, and a flux normalization at 0.15 TeV of $(6.3 \pm 1.1) \times 10^{-10} ~ \textrm{cm}^{-2} \textrm{s}^{-1} \textrm{TeV}^{-1}$. The integrated \textit{Fermi}-LAT flux from 1 GeV to 100 GeV during the VERITAS detection is $(4.1 \pm 0.8) \times 10^{\textrm{-8}} ~\textrm{cm}^{\textrm{-2}}\textrm{s}^{\textrm{-1}}$, which is an order of magnitude larger than the four-year-averaged flux in the same energy range reported in the 3FGL catalog, ($4.0 \pm 0.1 \times 10^{\textrm{-9}} ~ \textrm{cm}^{\textrm{-2}}\textrm{s}^{\textrm{-1}}$). The detection with VERITAS triggered observations in the X-ray band with the \textit{Swift}-XRT. However, due to scheduling constraints \textit{Swift}-XRT observations were performed 67 hours after the VERITAS detection, not simultaneous with the VERITAS observations. The observed X-ray energy spectrum between 2 keV and 10 keV can be fitted with a power-law with a spectral index of $2.7 \pm 0.2$, and the integrated photon flux in the same energy band is $(3.6 \pm 0.6) \times 10^{-13} ~\textrm{cm}^{-2} \textrm{s}^{-1}$. EBL model-dependent upper limits of the blazar redshift have been derived. Depending on the EBL model used, the upper limit varies in the range from z $<~0.9$ to z $<~1.1$