Analytical Method for Predicting Lateral Facing Deflection of Geosynthetic-Reinforced Soil Abutment Walls

Geosynthetic-reinforced soil (GRS) walls have been recently used as bridge abutments to directly support spread footings on the reinforced soil mass. This application reduces the requirement for using traditional deep foundations, such as piles or drilled shafts, to support bridge beams. GRS abutment walls are generally subjected to high footing loads that are close to the wall facing. Although GRS abutment walls with modular block facing have been the subject of a number of studies, there are limited methods to predict the profile of the lateral facing deflections along the height of the GRS abutment walls. Lateral deflections along the facing of GRS walls are of significant importance and are difficult to predict. In practice, design engineers need numerical modeling or software to predict the deflection profile. The objectives of this study were to develop an analytical approach to estimate lateral deflections of the wall facing along the height of the GRS abutment walls. Two sets of equations were developed, and experimental test results were used for verification of the proposed analytical approach. There is agreement between the results from proposed approach and the measured data. The maximum lateral deflections predicted from the proposed equations are almost identical to the measured data. The facing lateral deflection profiles with depth are within close range of measured data. The proposed analytical equations for determining lateral deflections provide an effective and simple tool in design of the GRS abutment walls

HIGH PROTECTION PERFORMANCE OF COATING SYSTEMS BASED ON ZINC RICH PRIMER AND FLUOROPOLYMER COATING

Coating systems based on zinc rich primer and fluoropolymer top coat were exposed for 8 years at different atmospheric stations in Vietnam: Hanoi, Ha Long and Nha Trang. For comparison the coating system with zinc rich primer and polyurethane topcoat was also tested. The degradations of coating systems were evaluated by gloss measurement and electrochemical impedance spectroscopy. The obtained results show that coating systems with zinc rich primer and top coatings based on fluoropolymer  and polyurethane topcoats show very high weather resistance and corrosion protection performance, but the systems with fluoropolymer are better than coating system with polyurethane topcoat

SOME RESULTS OF AIR MONITORING QUALITY IN HANOI AND ASSESSMENT OF AIR MONITORING METHODS USED IN VIETNAM

Joint Research on Environmental Science and Technology for the Eart

Diphosphine Bioconjugates via Pt(0)-Catalyzed Hydrophosphination. A Versatile Chelator Platform for Technetium-99m and Rhenium-188 Radiolabeling of Biomolecules

The ability to append targeting biomolecules to chelators that efficiently coordinate to the diagnostic imaging radionuclide, 99mTc, and the therapeutic radionuclide, 188Re, can potentially enable receptor-targeted “theranostic” treatment of disease. Here we show that Pt(0)-catalyzed hydrophosphination reactions are well-suited to the derivatization of diphosphines with biomolecular moieties enabling the efficient synthesis of ligands of the type Ph2PCH2CH2P(CH2CH2-Glc)2 (L, where Glc = a glucose moiety) using the readily accessible Ph2PCH2CH2PH2 and acryl derivatives. It is shown that hydrophosphination of an acrylate derivative of a deprotected glucose can be carried out in aqueous media. Furthermore, the resulting glucose-chelator conjugates can be radiolabeled with either 99mTc(V) or 188Re(V) in high radiochemical yields (&gt;95%), to furnish separable mixtures of cis- and trans-[M(O)2L2]+ (M = Tc, Re). Single photon emission computed tomography (SPECT) imaging and ex vivo biodistribution in healthy mice show that each isomer possesses favorable pharmacokinetic properties, with rapid clearance from blood circulation via a renal pathway. Both cis-[99mTc(O)2L2]+ and trans-[99mTc(O)2L2]+ exhibit high stability in serum. This new class of functionalized diphosphine chelators has the potential to provide access to receptor-targeted dual diagnostic/therapeutic pairs of radiopharmaceutical agents, for molecular 99mTc SPECT imaging and 188Re systemic radiotherapy.</p

Versatile Diphosphine Chelators for Radiolabeling Peptides with ^99mTc and ⁶⁴Cu

We have developed a diphosphine (DP) platform for radiolabeling peptides with 99mTc and 64Cu for molecular SPECT and PET imaging, respectively. Two diphosphines, 2,3-bis(diphenylphosphino)maleic anhydride (DP Ph) and 2,3-bis(di- p-tolylphosphino)maleic anhydride (DP Tol), were each reacted with a Prostate Specific Membrane Antigen-targeted dipeptide (PSMAt) to yield the bioconjugates DP Ph-PSMAt and DP Tol-PSMAt, as well as an integrin-targeted cyclic peptide, RGD, to yield the bioconjugates DP Ph-RGD and DP Tol-RGD. Each of these DP-PSMAt conjugates formed geometric cis/ trans-[MO 2(DP X-PSMAt) 2] + (M = 99mTc, 99gTc, natRe; X = Ph, Tol) complexes when reacted with [MO 2] + motifs. Furthermore, both DP Ph-PSMAt and DP Tol-PSMAt could be formulated into kits containing reducing agent and buffer components, enabling preparation of the new radiotracers cis/ trans-[ 99mTcO 2(DP Ph-PSMAt) 2] + and cis/ trans-[ 99mTcO 2(DP Tol-PSMAt) 2] + from aqueous 99mTcO 4 - in 81% and 88% radiochemical yield (RCY), respectively, in 5 min at 100 °C. The consistently higher RCYs observed for cis/ trans-[ 99mTcO 2(DP Tol-PSMAt) 2] + are attributed to the increased reactivity of DP Tol-PSMAt over DP Ph-PSMAt. Both cis/ trans-[ 99mTcO 2(DP Ph-PSMAt) 2] + and cis/ trans-[ 99mTcO 2(DP Tol-PSMAt) 2] + exhibited high metabolic stability, and in vivo SPECT imaging in healthy mice revealed that both new radiotracers cleared rapidly from circulation, via a renal pathway. These new diphosphine bioconjugates also furnished [ 64Cu(DP X-PSMAt) 2] + (X = Ph, Tol) complexes rapidly, in a high RCY (&gt;95%), under mild conditions. In summary, the new DP platform is versatile: it enables straightforward functionalization of targeting peptides with a diphosphine chelator, and the resulting bioconjugates can be simply radiolabeled with both the SPECT and PET radionuclides, 99mTc and 64Cu, in high RCYs. Furthermore, the DP platform is amenable to derivatization to either increase the chelator reactivity with metallic radioisotopes or, alternatively, modify the radiotracer hydrophilicity. Functionalized diphosphine chelators thus have the potential to provide access to new molecular radiotracers for receptor-targeted imaging. </p

Investigating the effectiveness of web‐based HIV self‐test distribution and linkage to HIV treatment and PrEP among groups at elevated risk of HIV in Viet Nam provinces: a mixed‐methods analysis of implementation from pilot to scale‐up

Introduction In Viet Nam, key populations (KPs) face barriers accessing HIV services. Virtual platforms can be leveraged to increase access for KPs, including for HIV self-testing (HIVST). This study compares reach and effectiveness of a web-based HIVST intervention from pilot to scale-up in Viet Nam. Methods A mixed-methods explanatory sequential design used cross-sectional and thematic analysis. The pilot launched in Can Tho in November 2020, followed by Hanoi and Nghe An in April 2021. Scale-up included Can Tho and Nghe An, with 21 novel provinces from April to December 2022. After risk assessment, participants registered on the website, receiving HIVST (OraQuick®) by courier, peer educator or self-pick-up. Test result reporting and completing satisfaction surveys were encouraged. Intervention reach was measured through numbers accessing the testing, disaggregated by demographics, and proportion of individuals reporting self-testing post-registration. Effectiveness was measured through numbers reporting self-test results, testing positive and linking to care, and testing negative and using HIVST to manage pre-exposure prophylaxis (PrEP) use. Thematic content analysis of free-text responses from the satisfaction survey synthesized quantitative outcomes. Results In total, 17,589 participants registered on the HIVST website; 11,332 individuals ordered 13,334 tests. Participants were generally young, aged <25 years (4309/11,332, 38.0%), male (9418/11,332, 83.1%) and men who have sex with men (6437/11,332, 56.8%). Nearly half were first-time testers (5069/11,332, 44.9%). Scale-up participants were two times more likely to be assigned female at birth (scale-up; 1595/8436, 18.9% compared to pilot; 392/3727, 10.5%, p < 0.001). Fewer test results were reported in scale-up compared with pilot (pilot: 3129/4140, 75.6%, scale-up: 5811/9194, 63.2%, p < 0.001). 6.3% of all tests were reactive (pilot: 176/3129, 5.6% reactive compared to scale-up: 385/5811, 6.6% reactive, p = 0.063); of which most linked to care (509/522, 97.5%). One-fifth of participants with a negative test initiated or continued PrEP (pilot; 19.8%, scale-up; 18.5%, p = 0.124). Thematic analysis suggested that community delivery models increased programmatic reach. Live chat may also be a suitable proxy for staff support to increase result reporting. Conclusions Web-based self-testing in Viet Nam reached people at elevated risk of HIV, facilitating uptake of anti-retroviral treatment and direct linkage to PrEP initiations. Further innovations such as the use of social-network testing services and incorporating features powered by artificial intelligence could increase the effectiveness and efficiency of the approach

Kinetics of neutralizing antibodies against Omicron variant in Vietnamese healthcare workers after primary immunization with ChAdOx1-S and booster immunization with BNT162b2

We studied the development and persistence of neutralizing antibodies against SARS-CoV-2 ancestral strain, and Delta and Omicron (BA.1 and BA.2) variants in Vietnamese healthcare workers (HCWs) up to 15 weeks after booster vaccination. We included 47 HCWs, including group 1 (G1, N = 21) and group 2 (G2; N = 26) without and with breakthrough Delta variant infection before booster immunization, respectively). The study participants had completed primary immunization with ChAdOx1-S and booster vaccination with BNT162b2. Neutralizing antibodies were measured using a surrogate virus neutralization assay. Of the 21 study participants in G1, neutralizing antibodies against ancestral strain, Delta variant, BA.1, and BA.2 were (almost) abolished at month 8 after the second dose, but all had detectable neutralizing antibodies to the study viruses at week 2 post booster dose. Of the 26 study participants in G2, neutralizing antibody levels to BA.1 and BA.2 were significantly higher than those to the corresponding viruses measured at week 2 post breakthrough infection and before the booster dose. At week 15 post booster vaccination, neutralizing antibodies to BA.1 and BA.2 dropped significantly, with more profound changes observed in those without breakthrough Delta variant infection. Booster vaccination enhanced neutralizing activities against ancestral strain and Delta variant compared with those induced by primary vaccination. These responses were maintained at high levels for at least 15 weeks. Our findings emphasize the importance of the first booster dose in producing cross-neutralizing antibodies against Omicron variant. A second booster to maintain long-term vaccine effectiveness against the currently circulating variants merits further research