Characterization of agar extracted from Gracilaria species collected along Tanzanian coast.

The study was conducted to investigate the effect of spatial variation, alkali treatment and the volume of extractant on yield and gel strength of agar for three Gracilaria species (G. salicornia, G. edulis and G. corticata) collected from the Tanzanian coast (Dar es Salaam, Tanga and Zanzibar). Treated and untreated G. corticata showed the highest yield (27 ± 0.7 % and 26.2 ± 1.3 % for treated and untreated, respectively), followed by G. salicornia then G. edulis. G. salicornia collected from Zanzibar showed the highest mass yield (22.9 ± 4.3 % for treated) followed by those collected from Tanga. Varying the volume for extraction showed no significant difference in mass yield where the p-value was >0.05. The highest gel strength was recorded from treated G. salicornia collected from Tanga (495 ± 29.5 gcm-2). Gel strength varied significantly between species. Spatial variability showed a significant difference in gel strength; the sample collected from Tanga showed the highest gel strength, followed by Zanzibar then Dar es Salaam. The variation due to the volume of distilled water used for extraction showed no significant difference in gel strength at a p-value >0.05. The highest gel strength was recorded at the volume of 1500 mL (467.5 ± 98.4 gcm-2), and the smallest gel strength was recorded at 500 mL. In all cases, there was a significant difference in mass yield and gel strength between treated and untreated samples. G. salicornia showed promising results as a local source of agar as it showed the highest gel strength though it produced an intermediate amount of agar. Based on the finding of this study, the volume of extraction of agar should be maintained as 1000 mL because by increasing the volume of extraction from 1000 mL to 1500 mL, the agar yield and gel strength don't change significantly. Agar yield and gel strength of Gracilaria species (G. salicornia, G. edulis and G. corticata) can be improved by alkali treatment, but further study is needed to determine the optimum amount and concentration of alkali to be used that will produce maximum yield and gel strength.

Relaxed complex scheme and molecular dynamics simulation suggests small molecule inhibitor of human TMPRSS2 for combating COVID-19.

As the coronavirus disease 19 (COVID-19) pandemic continues to pose a health and economic crisis worldwide, the quest for drugs and/or vaccines against the virus continues. The human transmembrane protease serine 2 (TMPRSS2) has attracted attention as a target for drug discovery, as inhibition of its catalytic reaction would result in the inactivation of the proteolytic cleavage of the SARS-CoV-2 S protein. As a result, the inactivation prevents viral cell entry to the host's cell. In this work, we screened and identified two potent molecules that interact and inhibit the catalytic reaction by using computational approaches. Two docking screening experiments were performed utilizing the crystal structure and holo ensemble structure obtained from molecular dynamics in bound form. There is enhancement and sensitivity of docking results to the holo ensemble as compared to the crystal structure. Compound 1 demonstrated a similar inhibition value to nafamostat by interacting with catalytic triad residues His296 and Ser441, thereby disrupting the already established hydrogen bond interaction. The stability of the ligand-TMPRSS2 complexes was studied by molecular dynamics simulation, and the binding energy was re-scored by using molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) binding free energy. The obtained compounds may serve as an initial point toward the discovery of potent TMPRSS2 inhibitors upon further in vivo validation.Communicated by Ramaswamy H. Sarma.

DFT and TD-DFT studies for optoelectronic properties of coumarin based donor-π-acceptor (D-π-A) dyes: applications in dye-sensitized solar cells (DSSCS).

A series of six coumarin based dye derivatives were investigated and their geometry and optoelectronic properties elucidated for suitability in dye-sensitized solar cells (DSSCs) using TD-DFT/B3LYP with 6-31G basis set. D-π-A schemes were developed by attaching various donors and acceptors to coumarin dye (CM) to calculate changes in their photovoltaic properties. D2-CM-A2 and D4-CM-A4 showed less dihedral angle because of the low steric effect between donor and connector. The D1-CM-A1 and D2-CM-A2 results of intramolecular charge transfer were higher because of low bond length and a strong group of electron donors. The results revealed that LUMO energies of D1-CM-A1, D2-CM-A2, D3-CM-A3 and D4-CM-A4 were higher than the conduction band edge of TiO2 electrode (-4.0 eV) suggesting that these dyes will inject the electrons into the conduction band of the semiconductor. In addition, the light harvest efficiency (LHE), open-circuit voltage (VOC) and band energy gap (Eg) values are calculated in the gas phase, as well as in the solvent phase. This study shows that D1-CM-D1 and D2-CM-A2 derivatives have better properties for application in the DSSCs.

Theoretical studies of optoelectronic and photovoltaic properties of D-A polymer monomers by Density Functional Theory (DFT).

In this research article, the new donor-acceptor (D-A) monomers developed using 4-methoxy-9-methyl-9 H-carbazole (MMCB) as electron donors and various electron acceptors. DFT and TD-DFT methods at the level of B3LYP with a 6-311 G basis set in a gas and chloroform solvent were used to calculate electronic and optoelectronic properties. To dissect the relationship between the molecular and optoelectronic structures, the impacts of specific acceptors on the geometry of molecules and optoelectronic properties of these D-A monomers were discussed. The calculations are also carried out on HOMO-LUMO, atomic orbital densities. The calculated band gap E g of the monomers considered increases 3,6-MMCB-OCP ≈ 3,6-MMCB-BCO < 3,6-MMCB-SDP < 3,6-MMCB-SCP < 3,6-MMCB-TCP < 3,6-MMCB-TDP < 3,6-MMCB-BCS < 3,6-MMCB-BCT in both in the gas and solvent phases. Subsequently, the optoelectrical properties of E HOMO , E LUMO , E opt , and E B energies were critically updated. Compared to different monomers, the far lower E g of the 3,6-MMCB-OCP and 3,6-CB-BCO has shown optoelectronic applications in organic solar cells like BHJ.

Theoretical design of low bandgap donor-acceptor (D-A) monomers for polymer solar cells: DFT and TD-DFT study.

Endeavors have been made to construct new donor-acceptor (D-A) monomers utilizing 9 H-carbazole (CB) as electron donors and different electron acceptors. All estimations were finished using DFT and TD-DFT, and B3LYP level with a 6-311 G basis set in the gas and chloroform solvent. The impacts of the distinctive acceptors on the geometry of molecules and optoelectronic properties of these D-A monomers were discussed to dissect the connection connecting the molecular structures and the optoelectronic properties. Likewise, the HOMO - LUMO energies, atomic orbital densities are calculated theoretically. Notwithstanding the charge transfer measure between the carbazole electron donor unit and the electron acceptor one is upheld by breaking down the optical spectra of the acquired monomers and the restriction of involved HOMO and LUMO. The outcomes show that the D-A monomers, CB-ODP, CB-TDP, and CB-SDP, are acceptable for optoelectronic applications in organic solar cells like BHJ.

In silico study of the inhibition of SARS-COV-2 viral cell entry by neem tree extracts.

The outbreak of COVID-19, caused by SARS-COV-2, is responsible for higher mortality and morbidity rates across the globe. Until now, there is no specific treatment of the disease and hospitalized patients are treated according to the symptoms they develop. Efforts to identify drugs and/or vaccines are ongoing processes. Natural products have shown great promise in the treatment of many viral related diseases. In this work, using in silico methods, bioactive compounds from the neem tree were investigated for their ability to block viral cell entry as spike RBD-ACE2 inhibitors. Azadirachtin H, quentin and margocin were identified as potential compounds that demonstrated viral cell entry inhibition properties. The structural re-orientation of azadirachtin H was observed as the mechanism for viral cell entry inhibition. These compounds possessed good pharmacodynamic properties. The proposed molecules can serve as a starting point towards developing effective anti-SARS-COV-2 drugs targeting the inhibition of viral cell entry upon further in vitro and in vivo validation.

Cation-π interactions drive hydrophobic self-assembly and aggregation of niclosamide in water.

The beneficial medicinal effects of niclosamide have been reported to be hampered by poor aqueous solubility and so a higher concentration dosage is required. In this work, we have studied the aggregation properties of niclosamide in water by varying the number of monomers. We have employed all-atom classical molecular dynamics simulation in order to explore such properties. The equilibrium structure exists in an aggregated state with structural rearrangements of the stacking units. Niclosamide monomers tend to form clusters in an orderly manner and tend to aggregate in parallel and antiparallel orientations of the phenyl rings as the monomers are increased in number from 4 to 9. Upon increasing the size from 9 to 14, and from 49 to 150, a considerable dominance of the metastable parallel arrangement is observed, resulting in the formation of a closely packed cluster with hydrophobic contacts. The metastable conformation self-arranges to a T-shape before forming a stable planar antiparallel displaced conformation. The aggregated π-π parallel and cation-π antiparallel clusters in water exist in a ß-conformer. We further observed that formation of a stable cluster aggregate entails the formation of an intermediate metastable cluster that disperses in solution forming a large stable cluster. We also discovered that movement of the water is faster in less aggregated clusters and as the cluster size increases, the mobility rate becomes much slower.

Disparities in Risk Factors Associated with Obesity between Zanzibar and Tanzania Mainland among Women of Reproductive Age Based on the 2010 TDHS.

The occurrence of overweight and obesity has serious health implications. The 2010 Tanzania Demographic and Health Survey data set was reanalysed to compare the prevalences of overweight and obesity between Mainland Tanzania and Zanzibar and to determine how demographic factors can predict overweight and obesity across the United Republic of Tanzania. About 7.92% of the Tanzanian women of reproductive age were obese, 15% were overweight, and 11.5% were underweight. Women from Mainland Tanzania (6.56%) were significantly less likely (AOR = 0.66, 95% CI: 0.53-0.82) to be affected by obesity as compared to women from Zanzibar (12.19%). The common predictors of obesity in Mainland Tanzania and Zanzibar were wealth index, marital status, and age. Whereas the place of residence and education level emerged as predictors of obesity in the Mainland Tanzania alone, the number of meals per day did so in Zanzibar. Most importantly, Zanzibar had a greater prevalence of obesity compared to Mainland Tanzania.