Nonlinear optical (NLO) materials have spanned a large area of science and technology owning to their potential applications in optoelectronics. The invention of the first Ruby laser has sparked a ...fresh interest in the area of nonlinear optics. The computational designing and experimental synthesis of organic and inorganic NLO materials with higher order nonlinearities come into vogue in the field of materials science. To date, several strategies including metal ligand framework, push pull mechanism, diradical character, and so on have been devised to enhance the NLO response of materials. In addition, introduction of diffuse excess electrons is an efficient approach to design noncentrosymmetric materials for nonlinear optics. The current review highlights a systematic array of different computational studies (covering the last decade of intensive research work) for the theoretical designing of NLO materials. In the present review, theoretical designing from the simplest NLO material to the complex alkali, alkaline earth, transition, and superalkali doped nanomaterials is summarized. The emergence of excess electrons strategy has played a pivotal role in enhancing the NLO properties especially hyperpolarizabilities. We expect that this review will provide a better understanding of the NLO responses of nanoclusters, paving the way for the advancement of hi-tech NLO materials to meet the real challenges in optoelectronics.
•Calix4pyrrole complexant based alkaline earthides have been designed.•Alkali metals act as source of electrons for alkaline earth metal atoms.•In alkaline earthide, the nature of compounds is ...confirmed by NBO and FMO analysis.•Alkaline earthides’ NLO response increases by two orders of magnitude in the presence of external electric field.
We report here rationally designed alkaline earthides using calix4pyrrole complexant. Alkali metal atoms are intercalated into calix4pyrrole while alkaline earth metals are kept outside the cavity to form M+(calix4pyrrole)M- (M+ = Li, Na & K; M- = Be, Mg & Ca). Under the action of four N atoms, the s valence electron of the alkali metal atoms overflows from the bottom of the cup to becomes excess electrons and enwraps the alkaline earth metal forming negative charge on alkaline earth metal. Nine complexes with general formula, M+(calix4pyrrole)M- (M+ = Li, Na and K; M- = Be, Mg and Ca) are designed and their geometric, electronic and nonlinear optical (NLO) properties are studied in detail. The alkaline earthide identities of the designed compounds are determined by distribution of electron densities in highest occupied molecular orbitals (HOMOs) and natural bond orbital (NBO) analyses. Presence of negative charges and localization of HOMOs on alkaline earth metals in all these complexes shows the alkaline earthide nature of these complexes. The spectra of partial density of states (PDOS) further confirm the presence of excess electrons on alkaline earth metals. These alkaline earthides show considerably high nonlinear optical responses with the first hyperpolarizabilities (βo) up to 1.98x104 au. Such high βo values are attributed to the presence of excess electron on alkaline earth metals. Moreover, their low transition energies from 2.06 to 3.87 eV reveal the susceptible and diffuse nature of excess electron. We also calculated the NLO response of designed complexes under the influence of external electric field of strength 0.001 a.u and found that NLO response of Li+Calix4pyrroleCa- has increased from 1.90 × 104 a.u to 8.19 x106 a.u. We expect that our work may inspire experimental chemists to explore synthetic, chemical and physical characterization of these new alkaline earthides.
Generalized linear model based gamma control chart Ali, Sajid; Asghar, Maria; Shah, Ismail
Quality and reliability engineering international,
February 2024, 2024-02-00, 20240201, Letnik:
40, Številka:
1
Journal Article
Recenzirano
Traditional monitoring techniques are frequently used for monitoring a response variable, while ignoring the other important variables. A simple linear regression model to introduce covariates‐based ...charts has received a lot of attention in the recent publications. When the response variable belongs to the exponential family, the generalized linear model (GLM) is a flexible approach to model a phenomenon. This study uses gamma distribution to introduce GLM‐based Shewhart‐type control charts. The monitoring statistic is developed using the Pearson residuals (PRs) obtained from the gamma regression model. The suggested charts' performance is evaluated using the run‐length properties and extensive Monte Carlo simulations. A comparison of Pearson‐residual to the deviance‐residual charts is also discussed in this article. Finally, to emphasize the significance of the study, the proposed control charts are implemented on a real‐life data set.
Abstract
Several control charts have been developed in the literature to monitor zero inflation using classic and simple linear regression models with covariates. Simple linear regression models may ...not be appropriate, especially when the response variable is skewed or count. When the response distribution follows the exponential family; however, the generalized linear model (GLM) gives a more flexible approach. The goal of this study is to use the Poisson hurdle model to provide GLM‐based Shewhart‐type control charts. To calculate monitoring statistics, the Pearson residuals (PRs) are obtained using the Poisson hurdle model. A detailed Monte Carlo simulation analysis is used to analyze the attributes of the suggested charts. Besides this, a real‐life data set is used to show the practical application of the charts.
Chiral Recognition of Amino Acids Using CC2 Porous Organic Cages Asghar, Maria; Lakhani, Ahmed; Asif, Misbah ...
The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory,
05/2023, Letnik:
127, Številka:
19
Journal Article
Recenzirano
Enantiomers have the same physical properties but different chemical properties due to the difference in the orientation of groups in space and thus Chiral discrimination is quite necessary, as an ...enantiomer of drug can have lethal effects. In this study, we used the CC2 cage for chiral discrimination of amino acids using density functional theory. The results indicated the physisorption of amino acids in the central cavity of the cage. Among the four selected amino acids, proline showed maximum interactions with the cage and maximum chiral discrimination energy is also observed in the case of proline that is 2.78 kcal/mol. Quantum theory of atoms in molecules and noncovalent interaction index analyses showed that the S enantiomer in each case has maximum interactions. The charge transfer between the analyte and surface is further studied through natural bond orbital analysis. It showed sensitivity of cage for both enantiomers, but a more pronounced effect is seen for S enantiomers. In frontier molecular orbital analysis, the least EH‑L gap is observed in the case of R proline with a maximum charge transfer of −0.24 e–. Electron density difference analysis is carried out to analyze the pattern of the charge distribution. The partial density of state analysis is computed to understand the contribution of each enantiomer in overall density of the complexes. Our results show that S-CC2 porous organic cages have a good ability to differentiate between two enantiomers. S-CC2 porous organic cages efficiently differentiated the S enantiomer from the R enantiomers of selected amino acids.
PCA provides qualitative differentiation of all strains, and PLS-DA accurately and specifically discriminated between S. aureus resistant and susceptible strains.
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•Silver ...nanoparticles serve as the SERS substrate and are used to distinguish between resistant and susceptible Methicillin-resistant Staphylococcus aureus (MRSA) strains.•Methicillin-resistant S. aureus (MRSA) resistant and susceptible strains have been compared to identify SERS spectrum features linked to the development of resistance.•PCA and PLS-DA are useful for differentiating Methicillin-resistant S. aureus (MRSA) strains.
Methicillin-resistant Staphylococcus aureus (MRSA) is gram positive bacteria and leading cause of a wide variety of diseases. It is a common cause of hospitalized and community-acquired infections. Development of increasing antibiotic-resistance by methicillin-resistant S. aureus (MRSA) strains demand to develop alternate novel therapies. Bacteriophages are now widely used as antibacterial therapies against antibiotic-resistant gram-positive pathogens. So, there is an urgent need to find fast detection techniques to point out phage susceptible and resistant strains of methicillin-resistant S. aureus (MRSA) bacteria. Samples of two separate strains of bacteria, S. aureus, in form of pellets and supernatant, were used for this purpose. Strain-I was resistant to phage, while the other (strain-II) was sensitive. Surface Enhanced Raman Spectroscopy (SERS) has detected significant biochemical changes in these bacterial strains of pellets and supernatants in the form of SERS spectral features. The protein portion of these two types of strains of methicillin-resistant S. aureus (MRSA) in their relevant pellets and supernatants is major distinguishing biomolecule as shown by their representative SERS spectral features. In addition, multivariate data analysis techniques such as principal component analysis (PCA) and a partial least squares-discriminant analysis (PLS-DA) were found to be helpful in identifying and characterizing various strains of S. aureus which are sensitive and resistant to bacteriophage with 100% specificity, 100% accuracy, and 99.8% sensitivity in case of SERS spectral data sets of bacterial cell pellets. Moreover, in case of supernatant samples, the results of PLS-DA model including 95.5% specificity, 96% sensitivity, and 96.5% accuracy are obtained.
In the current study, the exohedral doping of transition metals (TMs) in B
12
N
12
nanocages is explored as a new approach to enhance the NLO response and electronic properties. In this regard, a ...thorough investigation of exohedrally doped B
12
N
12
nanocages (M@x-B
l2
N
12
; where M is for transition metals included Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, and x = b
64
, b
66
, r
6
and r
4
) is performed. The TMs are doped over the bonds of BN (b
64
/b
66
), above four (r
4
) and six membered rings (r
6
). The spin polarized calculation data reveal that the most stable spin state increases from scandium (doublet) to manganese (sextet) and then decreases up to zinc (singlet). The binding energies of most of the complexes are in the range of − 12 kcal/mol to − 48 kcal/mol. NBO charges and bond order analysis are used to justify the nature and strength of interactions between TM and B
l2
N
12
nano-cage. TMs over B
12
N
12
cause a significant reduction in the E
H-L
gap regardless of their doping position or atomic number. The highest decrease in E
H-L
gaps is observed in the case of Sc@b
66
-B
12
N
12
(1.70 eV) compared to the bare B
12
N
12
nano-cage (6.14 eV). This appreciable decrease in E
H-L
gap is observed due to generation of new energy level above the original HOMO of bare B
12
N
12
nanocage. TMs doping causes a potential increase in the first hyperpolarizability (β
0
) to 1.39 × 10
4
au for Sc@b
64
-B
12
N
12
complex. TMs doped nanocages showed comparable NLO response to that of alkali metals doped analogues, which are considered best as best candidates for NLO response. These results will promote TMs doped B
12
N
12
nanocage as a suitable candidate for designing potential NLO materials.
The ability of surface-enhanced Raman spectroscopy (SERS) to generate spectroscopic fingerprints has made it an emerging tool for biomedical applications. The objective of this study is to confirm ...the potential use of Raman spectroscopy for early disease diagnosis based on blood serum. In this study, a total of sixty blood serum samples, consisting of forty from diseased patients and twenty (controls) from healthy individuals, was used. Because disease biomarkers, found in the lower molecular weight fraction, are suppressed by higher molecular weight proteins, 50 kDa Amicon ultrafiltration centrifugation devices were used to produce two fractions from whole blood serum consisting of a filtrate, which is a low molecular weight fraction, and a residue, which is a high molecular weight fraction. These fractions were then analyzed, and their SERS spectral data were compared with those of healthy fractions. The SERS technique was utilized on blood serum, filtrate and residue of patients with tuberculosis to identify characteristic SERS spectral features associated with the development of disease, which can be used to differentiate them from healthy samples using silver nanoparticles as a SERS substrate. For further analysis, the effective chemometric technique of principal component analysis (PCA) was used to qualitatively differentiate all the analyzed samples based on their SERS spectral features. Partial least squares discriminant analysis (PLS-DA) accurately classified the filtrate portions of healthy and tuberculosis samples with 97% accuracy, 97% specificity, 98% sensitivity, and an area under the receiver operating characteristic (AUROC) curve of 0.74.
SERS analysis of filtrate portions of blood serum samples of tuberculosis patients obtained by centrifugal filtration utilizing 50 kDa devices.
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