Adsorption/reaction energetics measured by microcalorimetry and correlated with reactivity on supported catalysts: A review

The formations and transformations of the chemical bonds of reactants and intermediates on cata- lyst surfaces occur in conjunction with the evolution of heat during catalytic reactions. Measure- ment of this evolved heat is helpful in terms of understanding the nature of the interactions be- tween the catalyst and the adsorbed species, and provides insights into the reactivity of the catalyst. Although various techniques have previously been applied to assessments of evolved heat, direct measurements using a Tian-Calvet microcalorimeter are currently the most reliable method for this purpose. In this review, we summarize the relationship between the adsorption/reaction energetics determined by microcalorimetry and the reactivities of supported catalysts, and examine the im- portant role of microcalorimetry in understanding catalytic performance from the energetic point of view.

Isothermal Microcalorimetry:A Review of Applications in Soil and Environmental Sciences

Isothermal microcalorimetry provides thermodynamic and kinetic information on various reactions and processes and is thereby a powerful tool to elucidate their mechanisms. Certain improvement in isothermal microcalorimetry with regard to the studies on soil and environmental sciences is briefly described. This review mainly focuses on the use of microcalorimetry in the determination of soil microbial activity, monitoring the toxicity and biodegradation of soil organic pollutants, the risk evaluation of metals and metalloids, the heat effect of ion exchange and adsorption in soil, and environmental researches. Promising prospects for the applications of the technique in the field are also discussed.

Investigation of in situ Growth of SrMoO_4 Nanoplates by Microcalorimetry

SrMoO4 nanoplates were synthesized by a facile reverse microemulsion method at room temperature.Energy evolution of this in situ growth process was monitored by means of a microcalorimeter.A sharp exothermic peak for the initial reaction and two discontinuous relatively weak exothermic peaks for the subsequent crystal growth emerged on the microcalorimetric heat flow curve.Based on the in situ thermokinetic data,the rate constants of the nucleation process and crystallization process at 298.15 K were calculated to be 4.078×10-3 and 5.033×10-4 s-1,respectively.The growth mechanism and energy evolution were investigated.

STUDY ON ANTIBACTERIAL ACTION OF 4-[P-ACETYLAMINO]BENZENESULFONAMIDOL SELENOMORPHOLINE BY MICROCALORIMETRY

Antibacterial action of 4-[p-acetylamino benzenesulfonamido] selenomorpholine (SeB) was studied by microcalorimetry with an LKB-2277 Bioactivity Moni-tor. It was found that SeB had the capacity to inhibit the metabolic growth of Escherichia coli. But in different sol-vent, the extent of inhibition is different. Removing the effect of solvent, we obtained the half-inhibition conce.ntra-tion(IC50) of SeB from the power-time curves. The value of IC50 of SeB was 1319μg ·mL-1.

Study on Mechanisms of Cd^(2+) Sorption on Goethite byMicrocalorimetry

A study on energy changes and mechanisms of Cd sorbed on goethite was performed using the technique ofmicrocalorimetry. The data of the amount of Cd sorption (Aq) and concentration of Cd in equilibrium solution(Ce), and the data of Aq and the heat effect (AH) caused by Cd^2+ sorption on goethite all fitted Langmuirisotherm. The amount of heat released from Cd sorption on goethite increased with the amount of Ce or Aq.The reaction process of Cd sorption on goethite may be divided into five stages and three plateaus, dependingon the variation of enthalpy change (.Hm) of Cd sorption with Aq, which implied three mechanisms ofinteraCtion between Cd and goethite. The experimental results showed that the microcalorimetry may beuseful for determination of microcalorie variation in soil.

Electrical Calibration for Calvet Type Microcalorimetry

The device construction and working principle of Calvet type heat conductive microcalorimetry are generally introduced in this paper. Based on previous work, we design a reactor vessel and its electrical calibration equipment according to our special study systems. The heat constant of our improved microalorimetry is gotten by means of electrical calibration on the basis of Tian's equation. The results gotten by integration method are identical with ones gotten by peak method. It shows that our improved device works well enough to develop further studies.

Biological Effect Studies of Norfloxacin Complexes on Tetrahymena and Escherichia Coli by Microcalorimetry

Norfloxacin complexes Co（nor）2.8H2O （nor=norfloxaein） and [Co（nor）（phen）]NO3.2H2O （phen=1,10-phenanthroline） were synthesized and their biological activity on Tetrahymena and Escherichia coli （E.coli） was assayed by means of microcalorimetry. Massive experimental parameters such as the growth constant k, inhibitory ratio I, half inhibition concentration IC5o and generation time TG were obtained. Data showed that with the increase of exposing complex concentration, both complexes exhibited strong inhibition during the growth of organisms. While toxic degrees were quite different on Tetrahymena and E.coli, due to various toxic mechanisms. And complex molecular volume and the ability of the complex penetrating into cells may be the keys.

Anti-microbial Activities of Protic Ionic Liquids Studied with Microcalorimetry Method

The anti-microbial activities of seven protic ionic liquids（ILs） against Escherichia coli and Staphylococcus aureus were studied by a micro-calorimetric method at 310 K.The bacterial growth rate constants were determined based on the bacterial growth power-time curves,andminimum biocidal concentrations were estimated.The results indicate that the protic ILs studied show inhibitory activities on the bacteria,implying a potential eco-toxicity to the microorganisms in the water system.Moreover,the inhibition effect of ionic liquids is related to the structure of the cation and anion of protic ILs.This type of proactive approach could aid in the assessment of the greenness of ILs to be used in the future.

Action of Selenium Compounds on the Cellular Metabolism by Microcalorimetry

A new method is introduced to study the action between biomaterials and organism. By using an LKB- 2277 bioactivity monitor and ampoule method, the fundamental thermogenesis curves of the metabolic process of pk-15 and the toxic effect of three kinds of selenomorpholine compounds on it were studied at 37℃. From the thermogenesis curves, the heat released by pk-15 metabolism was calculated. The results show that the selenium compounds all have toxic action on the metabolism process of pk-15 at the range of experimental concentrations. The sequence of the toxic action of selenium compounds is: Na2SeO3>β- ( N- selenomorpholine) -ethyl phenyike-tone hydrochloride > selenomorpholine.

Studies on the Reaction Between Laccase and o-methoxyphenol by Microcalorimetry

The reaction between Laccase and o methoxyphenol have been studied by LKB 2107 batch microcalorimetry system. Thermodynamic parameters Δ rH m , Δ G 0 , Δ G ≠ T ,) and kinetic parameters ( K m,k 2 ) have been determined. The process of the reaction has been analyzed from changes in energy by using the transition state theory. Two methods for enhancing catalytic power of Laccase are proposed. The results shown that formation of an enzyme substrate complex is“anticatalytic”. The enter and sole source of catalytic power is the stabilization of transition state; reactant state interactions are by nature inhibitory and only waste catalytic power.

Study on the Action of Sodium Selenite on the Mit ochondria Metabolism of Carassius auratus Hybrid Carps Liver by Microcalorimetry

By using an LKB\|2277 bioactivity monitor and a mpoule method, the fundamental thermogenesis curves of the metabolic process of liver mitochondria from Carassius auratus hybrid carps and the toxic effect of Na 2 SeO 3 on it were studied at 28 ℃.From the thermogenes is curves, the thermokinetic equations were established under different conditio n. The kinetics show that Na 2 SeO 3 has toxic action on the m etabolism process of Carassius auratus hybrid carps liver mitochondria.

Kinetics of Schiff base on Escherichia coli by microcalorimetry

The influence of four kinds of Schiff bases on a strain of Escherichia coli was studied by microcalorimetry. Differences in their capabilities of suppressing the metabolism of this bacterium were observed. The results show that the extent and duration of the inhibitory effect on the metabolism as judged from the multiplication rate constant, k , varies with different Schiff bases. The multiplication rate constant k , of Escherichia coli (in log phase) in the presence of Mo salicylioaldehyde thiadizole, Mo piperonaldehyde thiosemicarbazone and Mo 3 methoxy salicylicaldehyde thiadizole decreases with the increase of concentrations of compounds c , and the relationships between k and c , maximum heat production rate p m and c , peak time of growth curves t p and c are of linearity. For Mo 6 nitro pieronalde thiosemicarbazone, the multiplication rate constant is constant irrespective of variation in concentration. The sequence of antibiotic activity of Schiff base is : Mo salicylioaldehyde thiadizole>Mo 3 methoxy salicylicaldehyde thiadizole>Mo piperonaldehyde thiosemicarbazone>6 nitro pieronalde thiosemicarbazone.

STUDIES OF THE REACTION BETWEEN LACCASE AND p-PHENYLENEDIAMIME BY MICROCALORIMETRY

The molar reation enthalpy,the Michaelis constant and the observed rate constant of the reaction between the Rhus vernicifera laccase and p-phenylenediamine have been determined at 298. 15 K by LKB-2107 microcalorimetry system in 0.1 mol/L phosphate salt buffer (pH7. 4) to be △rHm=-136.36±0. 36kJ/mol, Km= 5. 58×10-3 mol/L and k1 =8. 63×10-3s-1, respectively. The catalyst activity of laccase withp-phenylenediamine as substrate has been determined to be EA=0. 045 IU in the experimental condition.The observed activation energy of non-enzymic step of the reaction, the Gibbs binding energy of the combination process of laccase and substrate have been also calculated. The physical significance of the determined parameters were discussed for different step of the reaction.

Thermochemical Studies of the Toxic Action of Heavy MetalIons on Escherichia coli by Microcalorimetry

By using an LKB2277 BioActivity Monitor (heat conduction microcalorimeter),stopped flow method,the thermogenetic curves of Escherichia coli growth at 37℃ inhibited by four kinds of heavy metal ions are determined,and parameters such as growth rate constants,inhibitory ratio,half inhibitory concentration etc.were obtained.The experimental results show that heavy metal ions can inhibit Escherichia coli growth obviously,but low concentration of Cu 2+ has a promoting action.The half inhibitory concentrations of Zn 2+ ,Cd 2+ ,Hg 2+ and Cu 2+ are 28.3,10.9,3.19 and 69.6μg.mL -1 ,respectively.Judged from the rate constant,the half inhibitory concentration and the molecular mass,the inhibitory sequence is Hg 2+ >Cd 2+ >Zn 2+ >Cu 2+ .This microclorimetric bioassay for acute cellular toxicity is based on metabolic heat evolution from cultured cells.The assay is quantitative,inexpensive,and versatile;moreover,toxicological information can be obtained with cell from other species of interest.

MICROCALORIMETRY ON BACILLUS SP.NTT-61

The fundamental growth thermograms of Bacillus sp.NTT-61 have been de- termined by microcalorimetric method.From these growth curves we got some thermo- kinetics data of its growth and its thermodynamic properties.

Study on Thermodynamics and Kinetics for the Reaction of Magnesium Diboride and Water by Microcalorimetry

An exothermic reaction between MgB2 and water was observed in our laboratory at high temperature, although no obvious reaction occurred at room temperature. The reaction process of MgB2 and water was therefore studied by using microcalorimetry. The results showed that the reaction enthalpies of MgB2 with water and the formation enthalpies of MgB2 at T = (323.15, 328.15, 333.15 and 338.15) K are (–313.15, –317.85, –322.09, –329.27) kJ?mol–1, and (–238.96, –237.73, –236.50, –234.30) kJ●mol–1, respectively. The standard enthalpy of formation and standard molar heat capacity of MgB2 obtained by extrapolation method are –245.11 kJ●mol–1 and 246 J●mol–1●K–1, respectively. The values of activation energy E, pre-exponential factor A and the reaction order for the reaction of MgB2 and water over the temperature range from 323.15 K to 338.15 K are 50.80 kJ●mol–1, 104.78 s–1 and about 1.346, respectively. The positive values of ΔG≠ and ΔH≠ and negative value of ΔS≠ indicate that the reaction can take place easily above 314.45 K.

The Sigma-1 Receptor as a Pharmacologic Chaperone: Energetics

Initially thought to be an opioid receptor subtype, Sigma-1 receptors (S1R) are now known to be unique proteins that have chaperone-like properties. As such, they play critical roles in cellular signaling, homeostasis, and cell survival. These roles offer significant insight for understanding homeostasis of normal physiologic processes, and the pathophysiologic consequences of disruption of normal function. Because of the broad nature of chaperone action, S1R agonists and antagonists represent potential drug discovery goals for the pharmacotherapeutic treatment of a variety of disorders that result from dysfunctional proteins. The present study summarizes the S1R as a pharmacologic chaperone crucial for protein folding and cellular homeostasis. Through literature review and thermodynamic analysis, it explores how S1R stabilizes target proteins, influencing neuroprotection and potential drug therapies. The binding of chaperones to target proteins is thermodynamically favorable, offering insights into treating diseases linked to protein misfolding.

Investigation of the effect of berberines alkaloids in Coptis chinensis Franch on Bacillus shigae growthby microcalorimetry

The inhibitory effects of five berberines alkaloids (BAs) from rhizoma ofCoptis chinensis Franch,a traditional Chinese medicinal (TCM) herb,on Bacillus shigae(B.shigae)growth were investigated by microcalorimetry.The power-time curves of B.shigae with and without BAswere acquired;meanwhile,the extent and duration of inhibitory effects on the metabolism wereevaluated by growth rate constants (k1,k2),half inhibitory ratio (IC50),maximum heat output(P_(max)),and peak time (t_p).The values of k1 and k2 of a shigae in the presence of the five BAsdecreased with the increasing concentrations of BAs.Moreover,P_(max) was reduced,and the value oft_p increased with increasing concentrations of the five drugs.The inhibitory activity varied withdifferent drugs.IC50 of the five BAs was respectively 75 mu g/mL for berberine,90 ng/mL forcoptisine,115 mu g/mL for palmatine,220 mu g/mL for epiberberine,and 400 mu g/mL forjatrorrhizine.The sequence of antimicrobial activity of the five BAs:berberine 】 coptisine 】palmatine 】 epiberberine 】 jatrorrhizine.The functional groups methylenedioxy at C2 and C3 on phenylring improve antimicrobial activity more strongly than methoxyl at C2 and C3 on phenylring.However,the effect of bacteriostasis is not significant with methylenedioxy or methoxyl at C9and C10 on phenyl ring.

Comparison of anti-bacterial activity of three types of di-O-caffeoylquinic acids in Lonicera japonica flowers based on microcalorimetry

The anti-bacterial activities of three types of di-O-caffeoylquinic acids(diCQAs) in Lonicera japonica flowers, a traditional Chinese medicine(TCM), on Bacillus shigae growth were investigated and compared by microcalorimetry. The three types of diCQAs were 3, 4-di-O-caffeoylquinic acid(3, 4-diCQA), 3, 5-di-O-caffeoylquinic acid(3, 5-diCQA), and 4, 5-di-O-caffeoylquinic acid(4, 5-diCQA). Some qualitative and quantitative information of the effects of the three diCQAs on metabolic power–time curves, growth rate constant k, maximum heat-output power Pm, and the generation time tG, total heat output Qt, and growth inhibitory ratio I of B. shigae were calculated. In accordance with a thermo-kinetic model, the corresponding quantitative relationships of k, Pm, Qt, I and c were established. Also, the half-inhibitory concentrations of the drugs(IC50) were obtained by quantitative analysis. Based on the quantity–activity relationships and the IC50 values, the sequence of inhibitory activity was 3, 5-diCQA > 4, 5-diCQA > 3, 4-diCQA. The results illustrate the possibility that the caffeoyl ester group at C-5 is the principal group that has a higher affinity for the bacterial cell, and that the intramolecular distance of the two caffeoyl ester groups also has an important influence on the anti-bacterial activities of the diCQAs.

Kinetics of the Action of Na_2SeO_3 on Bacillus subtilis Growth as Studied by Microcalorimetry

Microcalorimetric bioassay for acute cellular toxicity is based on metabolicheat production from cultured cells. The biological response to toxicants is the inhibition of theheat production rate in cells, and toxicity is expressed as the concentration of toxicant that is50% effective to this inhibition (IC_(50)). In this paper, the effect of Na_2SeO_3 on Bacillussubtilis growth was investigated at 37℃ by microcalorimetry. The relationship between growth rateconstants (k) and concentration of Na_2SeO_3(c) shows a logarithmic normal distribution, and IC_(50)is 20.3 μg/mL. All these thermokinetic information is readily obtained by an LKB 2277-204 heatconduction microcalorimeter. Microcalorimetry is a quantitative, inexpensive, and versatile methodfor toxicology research.