Straight Line Correlation Research Articles

Synthesis, characterisation and density functional theory (DFT) studies of a triazine ring with a mixed ligand Schiff base complexes

The novel Schiff base, (E)-4-((2-hydroxybenzylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one (L1), and its mixed ligand complexes with 2,4,6-tri(pyridin-2-yl)-1,3,5-triazine as an auxiliary ligand (L2) and different transition metal ions (Mn(II), Fe(III), Co(II), Ni(II), Zn(II) and Cd(II)) were synthesised. The 1H NMR spectra of L1 supported their geometrical structures, which was confirmed by X-ray crystallography. The packing of L1 is dominated by H…H, O…H, H…C, C…C, C…N, C…O and N…H interactions. Density functional theory (DFT) calculations showed excellent straight-line correlations between the calculated and experimental geometric parameters where the most stable isomer of L1 is stabilised by an OH…N hydrogen bond, and which agrees with the reported X-ray structure. The prepared complexes were characterised by elemental analyses, molar conductance measurements, IR, UV–vis, and 1H NMR spectroscopic methods. The elemental analysis data suggested a 1:1:1 [M:L1:L2] ratio for all the complexes. The molar conductance measurements of the complexes indicate their electrolytic nature in DMSO as solvent. The electronic absorption spectral data revealed the existence of an octahedral geometry for all complexes.

Combined Effects of Age and Comorbidities on Electrocardiographic Parameters in a Large Non-Selected Population.

Background: Previous studies have evaluated average electrocardiographic (ECG) values in healthy subjects or specific subpopulations. However, none have evaluated ECG average values in not selected populations, so we examined ECG changes with respect to age and sex in a large primary population. Methods: From digitized ECG stored from 2008 to 2021 in the Modena province, 130,471 patients were enrolled. Heart rate, P, QRS and T wave axis, P, QRS and T wave duration, PR interval, QTc, and frontal QRS-T angle were evaluated. Results: All ECG parameters showed a dependence on age, but only some of them with a straight-line correlation: QRS axis (p < 0.001, R2 = 0.991, r = 0.996), PR interval (p < 0.001, R2 = 0.978, r = 0.989), QTc (p < 0.001, R2 = 0.935, r = 0.967), and, in over 51.5 years old, QRS-T angle (p < 0.001, R2 = 0.979, r = 0.956). Differences between females and males and in different clinical settings were observed. Conclusions: ECG changes with ageing are explainable by intrinsic modifications of the heart and thorax and with the appearance of cardiovascular diseases and comorbidities. Age-related reference values were computed and applicable in clinical practice. Significant deviations from mean values and from Z-scores should be investigated.

3+2] Cycloaddition Reaction for the Stereoselective Synthesis of a New Spirooxindole Compound Grafted Imidazo[2,1-b]thiazole Scaffold: Crystal Structure and Computational Study

A new spirooxindole hybrid engrafted imidazo[2,1-b]thiazole core structure was designed and achieved via [3+2] cycloaddition reaction approach. One multi-component reaction between the ethylene derivative based imidazo[2,1-b]thiazole scaffold with 6-Cl-isatin and the secondary amine under heat conditions afforded the desired compound in a stereoselective manner. The relative absolute configuration was assigned based on single-crystal X-ray diffraction analysis. Hirshfeld calculations for 4 revealed the importance of the H…H (36.8%), H…C (22.9%), Cl…H (10.4%) and S…H (6.6%), as well as the O…H (4.7%), N…H (5.3%), Cl…C (1.6%), Cl…O (1.0%) and N…O (0.5%) contacts in the crystal stability. DFT calculations showed excellent straight-line correlations (R2 = 0.9776–0.9962) between the calculated and experimental geometric parameters. The compound has polar nature (3.1664 Debye). TD-DFT and GIAO calculations were used to assign and correlate the experimental UV-Vis and NMR spectra, respectively.

Rapid sanitary and technological control of culturing the producers of amylolytic enzymes.

It has been established that the biotechnological process of culturing bacillary microbial producers of amylolytic enzymes can be express-controlled by determining their ATP bioluminescence. The advantages of the method have been shown. The analytical review of producers of hydrolytic enzymes has made it clear how practical it is to use bacillary microorganisms for targeted secretion of amylolytic enzymes in biotechnological production. After monitoring bacillary microorganisms, it has been found advisable to choose Bacillus subtilis ATCC 6633 as the working culture due to its time of production of amylolytic enzymes and its biosynthetic activity. Reasons have been given for using the rapid ATP control method, which is based on the principle of bioluminescence. Different growth media have been compared and evaluated in order to intensify the quantitative biosynthetic activity of the microbial culture in the technological process of culturing bacillary microorganisms. The experiments have proved that growth media can be modified by introducing a number of carbohydrate–protein substrates as inducers of amylolytic complex gene expression. The latter manifests itself in the amylolytic activity accelerated by 12–24 hours, and causes an increase in the number of microorganisms (1.87–3.99 times as many as in the reference culture). Two methods of control (rapid bioluminescent and classic microbiological) have been used for correlative determination of the quantitative growth of Bacillus subtilis cells. Mathematical straight-line correlations have been obtained in a semilogarithmic system for the number of cells of the bacillary producer of the amylolytic enzyme complex. These correlations allow carrying out rapid control in a production environment. Along with the traditional rapid sanitary control in biotechnological production, which includes controlling the contamination of the equipment, personnel’s hands, and water, it has been suggested to perform proprietary technological express control of amylolytic enzyme biosynthesis using the culture Bacillus subtilis ATCC 6633

Semi-analytical model to predict the performance of cyclic steam stimulation oil wells

Prediction of the performance of oil wells under Cyclic Steam Stimulation (CSS) is challenging in complex and heterogeneous reservoirs, especially with limited data. Analytical and numerical simulation models do not usually give accurate predictions in such conditions. In this work, a semi-analytical model was developed to determine consistent mathematical relationships between the injected steam and some of the effective oil production parameters for more accurate prediction of oil production rates. Field investigation indicates that the change of the Cumulative Oil to Steam Ratio (COSR) to production days is related to a group of effective oil production parameters. This group of parameters includes the cumulative injected steam relative to the drainage volume, the oil net pay thickness relative to the gross pay thickness, and the vertical permeability relative to the thermal diffusivity. These parameters were arranged in two dimensionless groups. It was found that plotting these two dimensionless groups on Log–Log scale for any reservoir yields a straight line (correlation). For any reservoir under CSS, measurements of two steam cycles are sufficient to identify the constants of the proposed correlation. This method has been applied and validated on six reservoirs with different reservoir characterizations. Six different wells with a total of 43 steam cycles from these reservoirs were analyzed with the same approach. The mathematical relationships of the dimensionless groups were calculated, and the Log–Log plot was constructed for each well using the data of the first two cycles. Then, the proposed correlation was developed for each well and used to predict the well performance starting from the third steam cycle. At the end, the predicted performance of each well was compared with the corresponding actual measurements. The results showed that the average absolute percentage deviation between the actual and the predicted cumulative oil production through the well lifetime is less than 5% for the six wells. In addition, the absolute instantaneous deviation between the actual and the predicted cumulative oil production for each individual cycle in all cases is (1) less than 15% for about 42% of the tested CSS cycles, (2) between 15 to 25% for about 39% of the tested CSS cycles, and (3) higher than 25% for about 19% of the tested CSS cycles. This work is considered an original contribution to develop dimensionless relationships that can be used to predict the oil production of the CSS operations for reservoirs with limited data. The required data are the historical production rate, steam injection rate, and basic petrophysical parameters.

Association and heritability of traits of milk productivity and blood in the dairy cows

Numerous studies have shown that there is a certain association between the biochemical parameters of blood and milk. It is of big practical importance to determine the heritability of traits involved in the selection process, which gives breeders the opportunity to choose the direction of selection for the fastest solution of the tasks. The purpose of the researches was to establish the association between the indicators of the biochemical composition of milk and blood in the dairy cows, as well as to determine the heritability of the studied traits. It has been found in the course of researches that in most cases the correlations between the biochemical parameters of blood and milk were insignifi cant and unreliable. It can be seen that there is a slight correlation between the main indicators of blood and milk, which should be taken into account by breeders when conducting breeding to improve the quality of milk. The highest regression association has been observed between the content of carotene, calcium and phosphorus in blood and milk. If you increase these indicators in the blood by the corresponding unit, their content in milk will also increase by 0,90, 0,31 and 0,42, respectively. The heritability of milk productivity traits in most cases was at medium and low levels and ranged from 0,03 to 0,66 (straight-line correlation method) and from 0,03 to 0,44 (straight-line regression method). The heritability of hematological traits in most cases was at an average level and ranged from 0,14 to 0,98 (straight-line correlation method) and from 0,11 to 0,76 (straight-line regression method). The total protein content in the blood (h² =0,98 и 0,76) and the number of monocytes (h² =0,82 и 0,60) depended more on the genotypic features of the animal. The average level of heritability coeffi cients has been observed in the blood content of total lipids, phosphorus, eosinophils, young neutrophils, and lymphocytes.

EFFECT OF YOUNG’S MODULUS AND MINERALOGY ON ROCK STRENGTH

The mineralogical composition is one of the main properties controlling the rock strength. Mineralogical properties between unconfined compressive strength and Young's modulus and X-ray fluorescence spectrometer were assessed for four rock types, including basalt, limestone, sandstone, and siltstone, collected from different places in the new administrative capital of Egypt. During this respect, the present study presents correlation equations between the unconfined compressive strength and Young's modulus and X-ray fluorescence spectrometer of rocks. More than Seventy of specimens are prepared and tested of rocks. The mineralogical composition was determined by X-ray diffraction. The abundance of quartz and calcium oxide can affect rock strength. A high percentage of quartz and calcium oxide gave high strength to the rocks. This study indicates that there is a straight-line correlation between unconfined compressive strength and quartz for basalt, limestone, and siltstone rocks. This study indicates that there is a straight-line correlation between unconfined compressive strength and calcium oxide for sandstone rocks only. The proposed equations are valid only for selected rocks in the new administrative Capital of Egypt or close to it.

Application of Case-PBL method combined with SPSS software in teaching of medical statistics course

Objective To evaluate the effect of case-PBL method and case-PBL method combined with SPSS software on the teaching of medical statistics for medical undergraduates. Methods Students from two classes major in experimental medicine from Nantong University Xingling College were selected as Experimental Class 1 (using case-PBL teaching) and Experimental Class 2 (using case-PBL teaching combined with SPSS software). Each class attended lessons for five times. The teachers would send cases for each lesson one week in advance, and students would form into groups to access information, learn and discuss independently. Representatives from groups spoke in class, members would complement and discuss, while teachers offered guidance, review, analysis and summary. We shortened the discussion time in the class, and added instructions on the operation steps of SPSS software for case analysis and how to interpret the analysis result correctly in Experiment Class 2. The Control Class received traditional teaching. Questionnaires, process assessment and final assessment were used to evaluate teaching effectiveness. SPSS 21.0 software was used to implement variance analysis and chi-square test for comparison between groups. Results The scores of the two experimental classes were higher than those of the control class in the five process assessments(P<0.05). Experimental Class 2 was the best in three section process assessments including those of t-test, the rank sum test and the straight-line correlation (P<0.05). However, there was no difference in the theoretical test scores among the three classes (P=0.670). 94%-100% of the students in the two experimental classes believed that the teaching effects of the case-PBL method and case-PBL method combined with SPSS software were better than the traditional teaching method (P<0.05) in such areas as stimulating interest in learning, improving learning efficiency, etc. Students in Experimental Class 2 were more prone to think these methods improved teaching effect. Conclusion The case-PBL teaching combined with the application of SPSS software will further help students to systematically grasp the statistical knowledge and cultivate statistical practice ability. However, neither methods will improve students' theoretical test scores. Key words: Problem-based leaning; Case teaching; Medical statistics; Teaching effect

Defining and modeling of students’ professional thinking development dependence on their training process organization

The professional thinking issues are analyzed in the research. The authors pointed that the technical thought concepts, images and practical actions are in a complex and dynamic interaction with each other. The components of professional thinking are considered in detail. The training method based on the implementation of forming influence is proposed. The regression analysis of the students’ academic progress indicators who are trained by the traditional and innovative methodology with forming influence is conducted in the article. Analysis of thinking activity development levels in the process of professional tasks solving performed by the students of the control and experimental groups demonstrated the straight-line correlation dependence of the professional thinking development on the organization of professional activity in general and the training organization in particular.

Remarkably uniform oxygen isotope systematics for co-existing pairs of gem-spinel and calcite in marble, with special reference to Vietnamese deposits

Oxygen isotope systematics for co-existing pairs of gem-spinel and calcite in marble from Vietnam and other worldwide deposits have been determined in order to characterize the O-isotope fractionation between calcite and spinel. In Vietnam, the Δ18Occ–sp (=3.7±0.1‰ for six samples from the An Phu and Cong Troi deposits) is remarkably constant. The combination of these data with those obtained on calcite–spinel pairs of Paigutan (Nepal, n=2), Ipanko (Tanzania, n=1), and Mogok (Myanmar,=2) are also consistent with an overall Δ18Occ–sp of 3.6±0.3‰ for all the spinel samples (n=11). The straight line correlation δ18Occ=0.96 δ18Osp+4.4 is excellent despite their worldwide geographic spread. The increment method of calculating oxygen isotope fractionation gave a geologically unreasonable temperature of formation for both minerals at 1374°C when compared to temperatures obtained by mineral assemblage equilibrium of these marble type deposits, between 610 and 750°C. The constant Δ18Occ–sp reflects a constant temperature for this amphibolite facies assemblage, whose current best estimate is calculated at 620±40°C, but unquantified uncertainties remain.

Correlating Removal Rate to Directivity in Copper Chemical Mechanical Planarization

The relationship between directivity (Δ) and removal rate (RR) during copper chemical mechanical planarization (CMP) was investigated. We measured the high-frequency shear and normal forces generated by stick-slip (which has been routinely used to explain micro- and nano-scale interactions that lead to material removal), and found there to be a strong correlation between Δ (defined as the ratio of variances in shear force to those of normal force) and copper RR so long as the tribological mechanism remained constant. In cases where the tribological mechanism changed from “boundary lubrication” (BL) to “mixed lubrication” (ML), the slope of the straight-line correlation between Δ and RR was maintained, albeit it was shifted significantly lower. This was due to the ML regime consisting of hydrostatic or buoyant forces supporting the wafer, which led to less variability in frictional forces or less stick-slip events. Additionally, it was found that Δ and RR increased with sliding velocity while in BL due to an increase in stick-slip events. Conversely, Δ and RR decreased at lower sliding velocities while in ML due to an increase in hydrostatic or buoyant force supporting the wafer.

A new method of source and reservoir rock pyrolysis to determine the boiling point distribution of petroleum in rock samples

This paper presents a new method of source and reservoir rock pyrolysis used to understand the boiling point distribution of petroleum in rock samples. Experiments and simulations of the new incremental S1 method were performed on a range of rock types and API gravities (Black oil < 40, Volatile oil 40–45, Gas condensate ≥ 50 and Wet gas > 50). Comparison of the results from experiments and simulations are presented. The boiling point distribution results from the new incremental method can be used to infer the carbon number distribution of oil present in rock samples. However, the boiling point distribution data from the incremental S1 method is not adequate to determine the API Gravity of oil present in rock samples. Refractive index (RI) and density of oil have a straight line correlation. The boiling point distribution data from the Incremental S1 can be used in conjunction with the refractive index data to predict the composition of oil present in rock samples.

Ultrasonic technique for online measurement of bulk density of stamp charge coal cakes in coke plants

Coke oven batteries utilize stamp charged coal cakes for production of high quality blast furnace coke. Crushed coal blends are mechanically stamped to produce coal cakes. It is crucial to have a good control over this stamping operation so as to achieve a uniform bulk density (≈1100–1200kg·m−3 wet basis) of coal cake post stamping. This can facilitate robust and energy efficient coking operation. The dynamic nature of the stamping operation necessitates an online bulk density measurement technique. An ultrasonic technique which enables online measurement of bulk density during the stamping operation is described. The ultrasonic response was found to have a straight line correlation with bulk density (wet basis) and moisture content of stamped coal with an R2 value of 0.98. The effect of moisture content in the coal on the ultrasonic measurements is also discussed. A lab scale prototype was developed with integrated sensors to emulate online measurement. The prototype was found to have a measurement error of less than ±1.6%. This method can also be suitably adapted for online bulk density measurement of granular solids other than crushed coal.

Length-weight relationship and condition factor of five sub-populations of Trichogaster lalius (Osphronemidae) of central and eastern regions of India

Length-weight relationship along with condition factor was studied in five sub-populations of Trichogaster lalius collected from five different habitats of central and eastern parts of India characterized by different environmental conditions. Results of the current length-weight relationship study show that there is significant difference from the isometric b (3.0) value in the sub-populations of Lucknow Pond, River Gomti and Kolkata Pond, whereas there is no significant difference in the Malihabad and Barabanki sub-populations. This clearly indicates the negative allometric (b < 3) growth in the specimens collected from Lucknow, River Gomti and Kolkata and these sub-populations do not follow the cube law strictly. A positive straight line correlation was found between length and weight as the values of coefficient of correlation (r) of all the subpopulations of T. lalius varied between 0.92–0.97. The values obtained from covariance analysis for the difference between slopes of regression line for the sub-populations suggested that separate equations are required for five sub-populations of T. lalius. The Fulton’s condition factor (K) was used to evaluate the condition or fatness of fish which showed that the growth in all the sub-populations of T. lalius is satisfactory.

Extended scale for the hydrogen-bond basicity of ionic liquids

In the past decade, ionic liquids (ILs) have been the focus of intensive research regarding their use as potential and alternative solvents in many chemical applications. Targeting their effectiveness, recent investigations have attempted to establish polarity scales capable of ranking ILs according to their chemical behaviours. However, some major drawbacks have been found since polarity scales only report relative ranks because they depend on the set of probe dyes used, and they are sensitive to measurement conditions, such as purity levels of the ILs and procedures employed. Due to all these difficulties it is of crucial importance to find alternative and/or predictive methods and to evaluate them as a priori approaches capable of providing the chemical properties of ILs. Furthermore, the large number of ILs available makes their experimental characterization, usually achieved by a trial and error methodology, burdensome. In this context, we firstly evaluated COSMO-RS, COnductor-like Screening MOdel for Real Solvents, as an alternative tool to estimate the hydrogen-bond basicity of ILs. After demonstrating a straight-line correlation between the experimental hydrogen-bond basicity values and the COSMO-RS hydrogen-bonding energies in equimolar cation-anion pairs, an extended scale for the hydrogen-bond accepting ability of IL anions is proposed here. This new ranking of the ILs' chemical properties opens the possibility to pre-screen appropriate ILs (even those not yet synthesized) for a given task or application.

High-Resolution Rovibrational Spectroscopy of Carbon Monoxide Isotopologues Isolated in Solid Parahydrogen

We report high-resolution infrared absorption spectra of six different CO isotopologues isolated in cryogenic parahydrogen (pH2) solids. These data provide a stringent test for theories of nearly free molecular rotors in crystalline solids, such as crystal field theory, rotation-translation coupling theory, and the pseudorotating cage model. A gas-phase molecule rotates about its center-of-mass (C.M.); a trapped molecule instead rotates about its "center of interaction" (C.I.) with the trapping cage, which may differ from the C.M. for heteronuclear diatomics like CO. Isotopic manipulation of CO allows the systematic variation of the C.M. relative to the C.I. We report remarkably good straight line correlation plots between the observed matrix effects and C.M. locations. Extrapolation of these lines to the limit of vanishing matrix effects yields an "experimental prediction" of the C.I. in excellent (fortuitous?) agreement with the C.I. calculated using a linear pH2-CO-pH2 toy model.

Democracy and Development Nexus and the Intermediation Role of Development Communication in Africa

Democracy that potentially has the capacity for enhancing the responsiveness, accountability and transparency of the state seems to be at the heart of development. Arguably, democracy and development have an association, because the former facilitates the latter. In the face of efforts at democratic enterprise, consolidation and representative governance in Africa, democracy appears to be a mirage to the extent that it is largely flawed, fragile and fledgling. This study that relied on valuable secondary sources of data contended that while democracy and development have a cause and effect relationship, the relationship is not unilaterally a one-way directional one and therefore there is no straight-line correlation between them. The study equally canvassed for the intermediation role of development communication because democracy is a necessary and not a sufficient condition for development in Africa. The study concluded that development communication is a desideratum because it is a catalyst and an impetus for the actualization of the democracy potency in the African development agenda. Keywords: Democracy, development, intermediation, communication, Africa.

Two mathematical models of Mg and Sr partitioning into solution during incongruent calcite dissolution: Implications for dripwater and speleothem studies

Positive correlation between Sr/Ca and Mg/Ca in cave dripwaters and speleothem is often attributed to ‘prior calcite precipitation’ (PCP), where exclusion of Mg and Sr from calcite precipitated upstream of the dripwater/speleothem site results in enrichment in the Mg/Ca and Sr/Ca ratios of residual effluent. Modelling predicts that PCP will produce a straight line correlation in graphs of ln(Sr/Ca) vs. ln(Mg/Ca) with a theoretical slope that is given by ( Kd Sr − 1) / ( Kd Mg − 1) (calculated to be ∼ 0.88 ± 0.13) regardless of rock or absolute dripwater composition ( Sinclair et al., submitted for publication). While this makes the correlation slope potentially diagnostic for PCP, Mg and Sr are also preferentially released from calcite during incongruent calcite dissolution (ICD), and it is possible that ICD produces a similar correlation between ln(Sr/Ca) and ln(Mg/Ca). To examine this possibility, mathematical formulations for two different mechanisms of ICD are presented. Model 1 simulates net dissolution as a dynamic kinetic process where forward and reverse reactions compete: dissolution is congruent but ions are fractionated by a simultaneous reverse reaction where new calcite forms with Sr/Ca and Mg/Ca ratios that are determined by the solution composition and Kd Sr and Kd Mg. Model 2 simulates leaching of Mg and Sr from a fresh calcite surface by tracking the dissolution of a thin layer where high ion mobility allows the calcite to maintain a homogenous composition controlled by Kd Sr and Kd Mg. In both models, generalised kinetic equations are used in the derivations meaning that the results are not specific to a particular kinetic model. In both models of ICD, the mathematics predict that under conditions that may prevail during dissolution of limestone, the correlation between ln(Sr/Ca) and ln(Mg/Ca) is approximately linear with a slope given by ( Kd Sr − 1) / ( Kd Mg − 1). Thus, this property is not specific to just PCP. However, for both PCP and ICD, this slope is universal—expected to occur regardless of kinetics and the absolute composition of solution or host rock. A correlation slope of ∼ 0.88 in either karst waters or speleothem is therefore diagnostic for calcite–water interaction.

Study on the correlation between the change of CD4 + T cell counts and the variance of total lymphocyte counts in HIV/AIDS patients

Objective To analyze the correlation between the change of CD4 + T lymphocyte count (△CD4 +T) and the variance of peripheral blood total lymphocyte count(△TLC) and evaluate the effect of △TLC to substitute for CD4 +T count to predict HIV progression monitoring and the curative effect on clinical HAART treatment in HIV/AIDS patients. Methods Study the correlation between TLC and CD4 + T count and the correlation between △TLC and △CD4 + T count in 91 patients with HIV/AIDS. Study the date of ROC are-a, sensitivity, specificity, positive predictive value and negative predictive value for CD4 + T 200/μl, 350/μl to find the extent of TLC. Study the date of ROC area, sensitivity, specificity, positive predictive value and negative predictive value for △CD4 +T 50/μl、100/μl、200/μl、300/μl to find the extent of △TLC. Results The sig-nificant correlation (r value) between TLC and CD4 + T count was 0.716(P<0.01) in the patients. The re-markable dynamical correlations between△TLC and △CD4 + T were found comparing to that between TLC and CD4 + T count r value was 0.809(P<0.01). It was significant value in prediction CD4 + T count 200/μl and 350/μl with TLC cut-off 1300/μl and 1700/μl. Moreover,as more significant market to predict optimal △CD4 +T for 50/μl,100/μl,200/μl,for300/μl, △TLC were 170/μl,330/μl,630/μl,910/μl respectively. Conclu-sion There is straight line correlation between the change of CD4 + T cell counts and the variance of total lym-phocyte counts in HIV/AIDS patients. TLC especially △TLC for prediction of △CD4 + T can be available as a substitute method to estimate HIV disease progression and clinical HAART in some resource-constrained area of China. Key words: HIV; AIDS; CD4 Lymphocyte Count; Peripheral blood total lymphocyte count; Variance; correlation

Positive and negative aspects of soda/anthraquinone pulping of hardwoods

The positive aspects of the non-sulfur soda/anthraquinone (SAQ) process are mostly tied to improved energy efficiency while lower pulp brightness after bleaching is its most significant drawback. A credible method that quantifies bleachability as well as an approach that solves the problem for SAQ pulps from hardwoods will be described. A straight line correlation ( R 2 = 0.904) was obtained between O 2 kappa number and final light absorption coefficient (LAC) value after standardized OD 0E pD 1 bleaching of nine hardwood kraft pulps from three laboratories and one pulp mill. The bleachability of pulps from four different soda processes catalyzed by anthraquinone (AQ) and 2-methylanthraquinone (MAQ) was compared to that of conventional kraft pulps by comparing O 2 kappa number decrease and final LAC values. It was observed that a mild hot water pre-hydrolysis improved the bleachability of SAQ pulps to a level equal to that of kraft.