Artificial intelligence–based models for the qualitative and quantitative prediction of a phytochemical compound using HPLC method

Isoquercitrin is a flavonoid chemical compound that can be extracted from different plant species such as Mangifera indica (mango), Rheum nobile , Annona squamosal , Camellia sinensis (tea), and coriander ( Coriandrum sativum L.). It possesses various biological activities such as the prevention of thromboembolism and has anticancer, antiinflammatory, and antifatigue activities. Therefore, there is a critical need to elucidate and predict the qualitative and quantitative properties of this phytochemical compound using the high performance liquid chromatography (HPLC) technique. In this paper, three different nonlinear models including artificial neural network (ANN), adaptive neuro-fuzzy inference system (ANFIS), and support vector machine (SVM),in addition to a classical linear model [multilinear regression analysis (MLR)], were used for the prediction of the retention time (tR) and peak area (PA) for isoquercitrin using HPLC. The simulation uses concentration of the standard, composition of the mobile phases (MP-A and MP-B), and pH as the corresponding input variables. The performance efficiency of the models was evaluated using relative mean square error (RMSE), mean square error (MSE), determination coefficient (DC), and correlation coefficient (CC). The obtained results demonstrated that all four models are capable of predicting the qualitative and quantitative properties of the bioactive compound. A predictive comparison of the models showed that M3 had the highest prediction accuracy among the three models. Further evaluation of the results showed that ANFIS–M3 outperformed the other models and serves as the best model for the prediction of PA. On the other hand, ANN–M3proved its merit and emerged as the best model for tR simulation. The overall predictive accuracy of the best models showed them to be reliable tools for both qualitative and quantitative determination.     

Mass Activated Droplet Sorting (MADS) Enables High‐Throughput Screening of Enzymatic Reactions at Nanoliter Scale

Microfluidic droplet sorting enables the high‐throughput screening and selection of water‐in‐oil microreactors at speeds and volumes unparalleled by traditional well‐plate approaches. Most such systems sort using fluorescent reporters on modified substrates or reactions that are rarely industrially relevant. We describe a microfluidic system for high‐throughput sorting of nanoliter droplets based on direct detection using electrospray ionization mass spectrometry (ESI‐MS). Droplets are split, one portion is analyzed by ESI‐MS, and the second portion is sorted based on the MS result. Throughput of 0.7 samples s^?1 is achieved with 98 % accuracy using a self‐correcting and adaptive sorting algorithm. We use the system to screen ≈15 000 samples in 6 h and demonstrate its utility by sorting 25 nL droplets containing transaminase expressed in vitro. Label‐free ESI‐MS droplet screening expands the toolbox for droplet detection and recovery, improving the applicability of droplet sorting to protein engineering, drug discovery, and diagnostic workflows.     

Relaxations in thermosets. XIII. Effects of post-cure and aging on the sub-Tg relaxations of nonstoichiometric epoxide-based thermosets

The dielectric permittivity and loss of diglycidyl ether of bisphenol-A (DGEBA) cured with greater than and less than the stoichiometric amounts of diaminodiphenyl methane (DDM) have been measured over a temperature range 77–350 K prior to curing and gelation, after curing at about 340 K and further aging for a predetermined period. The height of the γ-relaxation peak monotonically decreases during the post-cure period and becomes masked by the contributions from the β-relaxation peak, whose height, in turn, first increases on postcuring to a same maximum value for both nonstoichiometric thermosets and then decreases. This decrease is attributed to physical aging effects. The β-relaxation peak shifts towards higher temperature on postcuring. Comparison between the changes in the dielectric properties of the saturated and starved thermosets show that while the γ-relaxation process may be attributed to the motion of the epoxide dipolar groups of the unreacted DGEBA, the β-relaxation process is not attributable entirely to the motion of ? OH groups and of the unreacted amines in the thermoset. Explanations involving the chain and network packing in the structure of a thermoset are necessary for the observed behavior of the β-relaxation process in amine saturated and starved thermosets.     

Acoustic emission from domain wall motion in ferroelectric lead germanate

Simultaneous visual observation and monitoring of the ultrasonic signals show that acoustic emission (AE) produced as Pb₅Ge₃O₁₁c-plate crystals undergo the ferroelectric hysteresis cycle results from domain wall nucleation and collapse. AE activity takes place predominantly at applied electric fields large enough to bring a crystal substantially towards its saturation polarisation. A notable feature observed in Pb₅Ge₃O₁₁ and Pb_5?xBa_xGe₃O₁₁ alloys is the existence of an abrupt threshold electric field, denoted by E_∞ in the high gain limit, for production of AE: as the electric field is increased beyond the threshold value, the amount of AE observed increases by several orders of magnitude. E_∞ depends linearly on the inverse of the c-plate sample thickness (1/d) and also upon sample temperature—falling to a minimum at about 70°C for Pb₅Ge₃O₁₁ and then rising steeply as the Curie temperature (178°C) is approached. E_∞ is also dependent on the rate of change of the applied electric field and as this is increased extrapolates to the high frequency limit of the coercive field. Measurements of crystal polarisation indicate a one-to-one correspondence between AE and the electrical Barkhausen pulses which occur during polarisation reversal—further evidence for domain nucleation and collapse as the source of AE. Optical and AE studies made simultaneously on gadolinium molybdate add confirmation that these particular processes are responsible for the AE produced by ferroelectric crystals.     

The crystal structure of phenoxatellurine dinitrate,C12H8O7N2Te

The crystal structure of phenoxatellurine dinitrate, C₁₂H₈O₇N₂Te, has been determined by x-ray diffractometer methods. The crystals are monoclinic, C2/c, a = 12.916(3), b = 14.050(5), c = 7.532(2) Å; β = 96.65(3)° at t = 22°. The molecule is nearly planar (175°), with the Te and O atoms of the central ring in special positions on the twofold symmetry axis. The bond distances for the central ring are: Te-C = 2.068(4) Å, C-O = 1.366(5), C-C = 1.388(6) with C-Te-C = 93.5(2)° and C-O-C = 128.2(5). The bond distances and angles in the phenyl rings do not differ significantly from the normally accepted values of 1.40 Å and 120°. The two nitrate groups are close to Te and are related by the twofold axis of symmetry. The independent distances and angles are: Te-O1 = 2.201(3), O1-N = 1.325(5), N-02 = 1.229(6), N-O3 = 1.204(6) Å, O2-N-O3 = 126.3(4), O1-N-02 = 117.1(4), O1-N-03 = 116.6(4)°. All hydrogen atoms were located at or near their calculated positions. The final R value for 1679 independent reflections was 0.031. The planarity of the molecule is discussed qualitatively in terms of simple molecular orbital theory.     

Lachnanthospirone,a dimeric 9-phenylphenalenone from the seeds of Lachnanthestinctoria ell.

The structure of lachnanthospirone [$\text{4}$] a novel dimeric pigment from $\text{Lachnanthes}$$\text{tinctoria}$ has been established from the X-ray crystal structure of a derivative [$\text{3}$] in which the spirolactone present in the natural product has been opened.     

Relaxations of thermosets. III. Sub-Tg dielectric relaxations of bisphenol-A–based epoxide cured with different cross-linking agents

The sub-T_g relaxations of bisphenol-A–based thermosets cured with diaminodiphenyl methane and diaminodiphenyl sulfone have been studied by dielectric measurements over the frequency range 12 Hz to 200 kHz from their ungelled or “least” cured states to their fully cured states. Both thermosets show two relaxation processes, γ and β, as the temperature is increased toward their T_gs. In the ungelled states, the γ process is more prominent than the β process. As curing proceeds, the strength of the γ process decreases and reaches a limiting value, while that of the β process initially increases, reaches a maximum value, and then decreases. An increase in the chain iength and the number of crosslinks increases the number of -OH dipoles and/or degree of their motions in local regions of the network matrix. This is partly caused by the decreasing efficiency of segmental packing as the curing proceeds. The sub-T_g relaxations become increasingly more, separated from the α relaxation during curing. Physical aging causes a decrease in the strength of the β relaxation of the thermosets as a result of the collapse of loosely packed regions of low cross-linking density, and this decrease competes against an increase caused by further crosslinking during the “post-cure” process.