Current Chinese Science - Volume 1, Issue 2, 2021

This paper is devoted to understanding relative navigation models that are used for space vehicles. The relative navigations models and approaches which are based on different systems (Inertial Navigation Systems (INS) Navigation Satellite System (GNSS) , Laser, Vision- Based, etc.) are compared. These models and approaches can be used individually or combined for solving relative navigation problems. Advantages and disadvantages of the models vary according to the usage area, platform type, and environment. Different methods and approaches exist in addition to different estimation and optimization algorithms for adaptation, control, and sensor fusion. Most of the models assume perfect attitude conditions. This study considers satellites' position estimates according to each other within formation on the Low Earth Orbit (LEO). Also, the aim of this article is to understand correlation between the relative navigation systems and the effectiveness of the algorithms which are used for estimating states during constellation or formation flight.

Among the huge number of fluorescent compounds described recently, pyrazole derivatives could play a paramount role in the design of probes for bioimaging applications–an important and simple tool for modern biology because of their easy synthetic methodologies, remarkable optical properties and chelating points. In this mini-review, we highlighted some pyrazole derivatives that have shown remarkable performance in this area; from the detection of chromium (III) with limits of detection of 37 10-12 M to sensing glutathione in biological samples, as well as small molecule labeling of drugs and identifying unhealthy cells such as HeLa and labeling subcellular organelles. Evidently, this important class of N-heterocyclic compounds is part of interesting applications.

Background: Resistance to the critical first line anti-tubercular drug, Pyrazinamide, is a significant obstacle to achieving the global end to tuberculosis targets. Approximately 50% of multidrug- resistant tuberculosis and over 90% of extensively drug-resistant tuberculosis strains are also Pyrazinamide resistant. Pyrazinamide is a pro-drug that reduces the duration of tuberculosis therapy time by 9-12 months, while used as an anti-biotic in the 1st- & 2nd-line tuberculosis treatment regimens. Pyrazinamidase is an enzyme encoded by pncA gene, which is responsible for the amide hydrolysis of pyrazinamide into active pyrazinoic acid. Pyrazinoic acid can inhibit trans-translation by binding to ribosomal protein S1 and competing with tmRNA, the natural cofactor of ribosomal protein S1. Although pncA mutations have been commonly associated with pyrazinamide resistance, a small number of resistance cases have been associated with mutations in ribosomal protein S1. Ribosomal protein S1was recently identified as a possible target of pyrazinamide based on its binding activity to pyrazinoic acid and the capacity to inhibit trans-translation. Objective: Despite the critical role played by pyrazinamide, its mechanisms of action are not yet fully understood. Therefore, this study is an effort to explore the resistance mechanism toward pyrazinamide drug in Mycobacterium (M.) tuberculosis. Methods: An extensive molecular dynamics simulation was performed using the AMBER software package. We mutated residues of the binding site (i.e., F307A, F310A, and R357A) in the RpsA S1 domain to address the drug-resistant mechanism of RpsA in complex that might be responsible for pyrazinamide resistance. Moreover, it is challenging to collect the drug mutant to combine the complex of a protein by single- crystal X-ray diffraction. Thus, the total three structures were prepared by inducing mutations in the wild-type protein using PyMol. Results: The dynamic results revealed that a mutation in the binding pocket produced pyrazinamide resistance due to the specificity of these residues in binding pockets, which resulted in the scarcity of hydrophobic and hydrogen bonding interaction with pyrazinoic acid, increasing the CAdistance between the binding pocket residues as compared to wild type RpsA that led to structural instability. Conclusion: The overall dynamic results will provide useful information behind the drug resistance mechanism to manage tuberculosis and also helps in better management for future drug resistance.

Background: Selection of Sustainable Suppliers is a key term in sustainable supply chain management. This is the reason to choose the supplier who will support the company to implement sustainability in its business, especially in the supply chain. Objective: The aim of this paper is to establish a new innovative model for decision-making based on a fuzzy approach. Methods: This decision-making problem is solved by applying multi-criteria decision-making since there are several criteria according to which a decision should be made: economic, social, and environmental. In order to make the final decision on the supply chain better and safer, the social criteria were modified in this paper, adding ethical criteria. The example with modified social criteria in this paper was shown on the example of the company "VoĦ#135;ar" BrĦ#141;ko, which deals with the production of food products. In this paper, the fuzzy Measurement Alternatives and Ranking, according to the Compromise Solution Method, was used. Results: The findings have shown that supplier A1 has the best results, which were confirmed with the first sensitivity analysis. However, the second sensitivity analysis has shown that supplier A5 was better than supplier A1 in 14 scenarios. Due to these findings, no unanimous decision can be made about which supplier among the two, in this case, would contribute more. Conclusion: This paper has shown that the selection of sustainable suppliers is crucial for any company focused on the principles of sustainability in business. Moreover, this paper has shown that it is sometimes very difficult to select just one supplier.

Background: Probiotic cellular components could be an interesting alternative to live probiotics, which could potentially cause safety problems in open aquatic environments. Objective: The cell wall (CW), peptidoglycan (PG) and lipoteichoic (LTA) were extracted from probiotic strain of Bacillus pumilus SE5, and these biomolecules were used to develop the possible application in fish aquaculture. Methods: Grouper (Epinephelus coioides) juveniles were fed with either a basal control diet or the basal diet supplemented with CW, PG and LTA respectively for 60 days, and the growth performance, digestive enzymes activities, serum immune responses and immune genes expression in head kidney were determined. Results: Dietary supplement PG and LTA significantly improved final body weight (FBW), weight gain rate (WGR), specific growth rate (SGR) and protein efficiency ratio (PER), while significantly decreased feed conversion ratio (FCR) was noticed in all the treatments compared with the control group. Dietary supplements of CW, PG and LTA enhanced the activities of trypsin, lipase and amylase in the liver. Serum complement C3 and IgM levels as well as, AKP, ACP and SOD activities elevated significantly in fish fed the PG and LTA containing diets. Furthermore, PG and LTA containing diets, significantly up-regulated expression of TLR2, NOD2, IL-8, IgM and three antibacterial peptides genes (epinecidin-1, hepcidin-1 and β-defensin) in the head kidney. Conclusion: PG and LTA originated from probiotic B. pumilus SE5 could effectively enhance the growth performance, feed utilization, digestive ability and boost innate and adaptive immune system of E. coioides.

The results of spectral-kinetic studies in the field of nanophotochromism of the core128;’ shell type hybrid compounds are integrated. The properties of photochromic nanoparticles based on photochromic spirocompounds (spiropyrans and spirooxazines), chromenes, and diarylethenes and nanoparticles of noble metals (Ag and Au), diamonds, graphene and its oxide, silica, fullerenes, and quantum dots are considered. Preparation methods of photochromic nanoparticles have been developed.

Background: The development of environment-friendly and cost-effective palladium( Pd) based nanocomposite is of high interest for catalytic applications. Objective and Methods: In this paper, a porous Pd/two-dimensional-material (graphene oxide (GO) and reduced graphene oxide (rGO)) nanocomposite was synthesized with a green and facile method, without adding any additional reductant, surfactant and special solvent. Results: The catalytic activity of the Pd/rGO composite was investigated using the 4-nitrophenol (4-NP) reduction reaction in the presence of sodium borohydride (NaBH4). The results showed that the Pd/rGO nanocomposite not only exhibited much higher catalytic activity than the pure porous Pd catalyst but also showed a very good catalytic stability due to the less Pd aggregation and increased local 4-NP concentration arose from rGO bonding attraction. Besides, the Pd-rGO nanocomposite showed a kapp value of 0.383 min-1, which was 13 times higher than the pure Pd (0.0292 min-1), as well as a reliable 4-NP conversion rate of over 97%. Conclusion: This study may provide a route for green-design and synthesis of heterogeneous catalyst composites with lower cost and better performance.

Background: Hydrophilic nanomaterials have been extensively exploited their applications in the field of hybrid water treatment membranes. However, some of the modification process to nanomaterials may be complicated, and the nonselective pores caused by the poor compatibility between nanoparticles and the polymer matrix impair the rejection efficiency for ultrafiltration application. Thus, it is highly desirable to develop a kind of effective nano dopant with favorable compatibility by a facile way for the preparation of ultrafiltration membranes. Objective: The aim of this study was to fabricate a novel environmentally friendly and low-cost nano additive with good compatibility for the preparation of ultrafiltration membranes. Methods: Hydroxyapatite nanotubes were prepared via a biomimetic process, and then SA was coated on the surface of hydroxyapatite nanotubes. Subsequently, a series of hybrid ultrafiltration membranes were fabricated with different amounts of modified HANTs and polyethersulfone (PES). Results: Exhaustive characterizations were conducted for the membranes, including hydrophilicity, porosity, mean pore size, morphologies and UF performance test. The highest water flux of the hybrid membranes displayed 1.9 times that of the original PES membrane. Meanwhile, the hybrid membrane with 0.2% hydroxyapatite nanotubes obtained elevated antifouling ability, achieving a flux recovery ratio of 85.6%. Conclusion: The facile coating of SA endowed the nanotubes improved hydrophilicity and meanwhile enhanced the compatibility between PES and HANTs. This work provides a facile way in the construction of green nanofillers and promising results in the preparation of hybrid UF membranes.

Objective: To review the available sole anti-inflammatory immunomodulators or adjuvants, different from pro-inflammatory ones, which elicit a Th2 immunity while inhibiting but without abrogating Th1/Th17 immunities. Adjuvants that are useful to develop vaccines for T-cell mediated autoimmune conditions. Methods: A literature search using PubMed and Google Scholar databases was made to identify reports regarding adjuvants, mechanisms of action, pro-inflammatory autoimmunity and vaccines to treat it, immunosuppressive agents, dendritic cells, helminths, immunotolerance, and infectious diseases causing autoimmunity. Results: Some anti-inflammatory drugs to treat autoimmune diseases inhibit DNA or protein synthesis causing global immunosuppression, which is reduced by using biologics to block key steps in the inflammatory cascade. Fucosylated glycans from helminths, which are anti-inflammatory but not immune-suppressive, offer an avenue to develop better drugs. Fucosylated glycans bind to DC-SIGN, a receptor on dendritic cells, entering the cells via receptor-mediated endocytosis, biasing their immunoresponse to a sole Th2 anti-inflammatory immunity, while inhibiting the proinflammatory Th1/Th17 immunities. New anti-inflammatory drugs are particular plant-derived fucosylated glycosides with immunological properties like those of helminth-derived glycans. Another class of anti-inflammatory immunomodulators is ligands of the aromatic-hydrocarbon receptor, which by activating this intracellular receptor, boosts the differentiation of regulatory Tcells, inducing an anti-inflammatory immunity. However, aromatic ligands can also stimulate a pro-inflammatory response. Exogenous aromatic ligands are usually delivered intracellularly using carriers like nanoparticles, which upon translocation to the nucleus, activate this receptor. Conclusion: Autoimmune conditions and some infectious diseases, characterized by organ damage due to pro-inflammatory autoimmune immunoresponses, could benefit from nonimmunosuppressive agents to modulate immunity; this way, averting a damaging inflammation.

Background: Coronavirus disease (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is designated as a global pandemic. Elderly men with underlying medical conditions are more susceptible to SARS-CoV-2 infection and usually develop severe/ critical illness, therefore more attention we should be paid to them. Objective: Describe methods that may help old patients with COVID-19 recover. Methods: A case of a 91-year-old male COVID-19 patient in Haihe Hospital, Tianjin, China, has been reported here who survived after receiving supportive medical treatment and psychological assistance. Results: In addition to medical interventions, psychological support may be needed to better treat COVID-19 patients, including the elderly. Conclusion: Special care should be provided for elderly COVID-19 patients. Mutual understanding and support between patients and health-care workers are essential during this pandemic.