Nitrification activity in the presence of 2-chlorophenol using whole nitrifying cells and cell-free extracts: batch and SBR assays.

Kinetic assays with a nitrifying consortium with whole nitrifying cells amended with 5 mg 2-CP-C/L and 100, 200, 300, or 500 mg NH4+-N/L were carried out in batch and nitrifying sequencing batch reactor (SBR) cultures. No nitrification activity was observed in batch assays with 100 mg NH4+-N/L and 5 mg 2-CP-C/L. Nevertheless, increasing the ammonium concentration from 200 to 500 mg NH4+-N/L allowed simultaneous ammonium and nitrite oxidation even in the presence of 5 mg 2-CP-C/L plus the halogenated compound consumption. Under these conditions, the ammonium monooxygenase enzyme participated in 2-CP consumption. Complete nitrification and simultaneous elimination of 5 mg 2-CP-C/L were achieved in the SBR amended with 200-500 mg NH4+-N/L. The inhibitory effect of 2-CP on the nitrite oxidation process completely disappeared under these conditions. Assays with nitrifying cell-free extracts, ammonium (100 mg NH4+-N/L), and 2-CP (5 mg 2-CP-C/L) were also conducted. In the absence of 2-CP, the nitrifying cell-free extracts maintained up to 60% of the nitrifying activity compared to whole-cells. Contrary to whole-cell assays, cell-free extracts were capable of simultaneously oxidizing ammonium and consuming 2-CP. However, the inhibitory effect of 2-CP on nitrification was still present as lower specific rates of ammonium consumption and nitrate production were obtained. Thus, these assays indicate that the presence of 2-CP affects both, the ammonium transport mechanism and the activity of nitrifying enzymes. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03764-z.

Viscoplastic properties of laponite-CMC mixes.

In this dataset, 15 samples of laponite-CMC mixes were realized and their viscoplastic properties are determined. Rheological parameters are then expressed as a function of age and components concentrations.

[Early rehospitalization of persons aged 75 years or older admitted to a post-emergency general medicine department: Rates and predictive factors]. / Réhospitalisation précoce des personnes âgées d'au moins 75 ans admises dans un service de médecine polyvalente post-urgence : taux et facteurs prédictifs.

INTRODUCTION: Given the implications of rehospitalization at the individual and societal level, it seems important to identify elderly persons (EP) at risk. We analyzed the predictive factors of early rehospitalization in EP aged 75 years or more hospitalized in a medicine department. METHODS: A single-center retrospective study that included EP aged 75 years or more hospitalized in a polyvalent medical department following an emergency admission. Patients who died during the hospitalization, who had been transferred or hospitalized during the previous month, were excluded. The impact of sociodemographic, administrative and biomedical data on rehospitalization at one month was analyzed. RESULTS: A total of 319 hospitalizations were collected (mean age of patients: 84.7±5.7 years). Most lived at home (80.2%) and among these 8.4% had no home help. The rehospitalization rate was 16.3%, among which 2/3 were related to the reason for the initial hospitalization. Among the predictive factors found in the univariate analysis (male sex, multiple diseases, polypharmacy, multiple hospitalizations, cognitive disorders and calls to emergency services), only the presence of at least two previous hospitalizations in the year (odds ratio [OR]=2.10; 95% confidence interval [95%CI] [1.01-4.39]; P=0.048) and the presence of confusion without dementia (OR=3.78; IC 95% [1.09-13.06]; P=0.04) were significant. Discharge to a rehabilitation unit and increased support at home did not affect the likelihood of rehospitalization. CONCLUSION: The rehospitalization of EP is frequent and difficult to anticipate because there are few predictors and their impact is weak. The most important factors were medical: multiple hospitalizations and confusion without dementia.

Kinetic and physiological evaluation of ammonium and nitrite oxidation processes in presence of 2-chlorophenol.

The effect of 2-chlorophenol (2-CP) on ammonium and nitrite-oxidizing processes was kinetically evaluated in batch cultures with nitrifying sludge at steady state. Assays with ammonium or nitrite as energy source and 2.5, 5.0, or 10.0 mg 2-CP-C/l were conducted. Control assays without 2-CP were also performed. Ammonium-oxidizing activity was completely inhibited at the different 2-CP concentrations, whereas nitrite-oxidizing activity was present as nitrite was completely consumed and converted to nitrate irrespectively of 2-CP concentration. In the presence of 2.5 and 5.0 mg 2-CP-C/l, no significant effect on specific rates of nitrite consumption and nitrate production was observed, but a significant decrease on these parameters was observed at 10.0 mg 2-CP-C/l. The nitrifying sludge previously exposed to 2-CP was unable to completely recover its ammonium and nitrite oxidation capacity. Nevertheless, complete 2-CP consumption was achieved in all assays. The effect of 2-CP on ammonium oxidation was observed at kinetic and metabolic pathway level, whereas the effect on nitrite oxidation was observed only at kinetic level. The results obtained in this work evidenced that in order to achieve a successful nitrification process the presence in wastewater of even 2.5 mg 2-CP-C/l should be avoided.

[Twinkling artifact on Doppler US: clinical presentations]. / L'artefact de scintillement en écho-Doppler et situations cliniques.

Twinkling artifact characterized by a rapidly fluctuating mixture of Doppler signals occurs behind a strongly reflecting granular interface such as urinary tract stones or gallstones. It may occurs in association with several clinical situations, and may sometimes be helpful for diagnosis while it may sometimes be a pitfall that must be recognized by the sonographer. After reviewing the technical nature of this artifact, several cases will be presented to illustrate the advantages and pitfalls related to this artifact.

p-Cresol biotransformation by a nitrifying consortium.

The oxidizing ability of a nitrifying consortium exposed to p-cresol (25 mg CL(-1)) was evaluated in batch cultures. Biotransformation of the phenolic compound was investigated by identifying the different intermediates formed. p-Cresol inhibited the ammonia-oxidizing process with a decrease of 83% in the specific rate of ammonium consumption. After 48 h, ammonium consumption efficiency was 96+/-9% while nitrate yield reached 0.95+/-0.06 g NO(3)(-)-Ng(-1)NH(4)(+)-N consumed. High value for nitrate production yield showed that the nitrifying metabolic pathway was only affected at the specific rate level being nitrate the main end product. The consortium was able to totally oxidize p-cresol at a specific rate of 0.17+/-0.06 mg p-cresol-Cmg(-1) microbial protein h(-1). p-Cresol was first transformed to p-hydroxybenzaldehyde and p-hydroxybenzoate, which were later completely mineralized. In the presence of allylthiourea, a specific inhibitor of ammonia monooxygenase (AMO), p-cresol was oxidized to the same intermediates and in a similar pattern as obtained without the AMO inhibitor. AMO seemed not to be involved in the p-cresol oxidation process. When p-hydroxybenzaldehyde was added (25 mg CL(-1)), the nitrifying process was inhibited in the same way as observed with p-cresol, indicating that p-hydroxybenzaldehyde could be the main compound responsible for nitrification inhibition. p-Hydroxybenzaldehyde was accumulated during 15 h before complete consumption at a specific rate value eight times lower than the p-cresol consumption rate. Results showed that p-hydroxybenzaldehyde oxidation was the limiting step in p-cresol mineralization by the nitrifying consortium.

Qualitative and quantitative determination of a humic model compound in microbial cultures by cyclic voltammetry.

The humic model compound, anthraquinone-2,6-disulfonate (AQDS), was characterized and measured in microbial cultures by cyclic voltammetry (CV). Under the experimental conditions, the formal reduction potential (E(o')) of the couple AQDS/AHQDS was found to be of -0.520 V vs. SCE (standard calomel electrode) at pH value of 7.0. Control experiments showed that there were no interferences of the culture medium or the microbial consortium on the quantitative determination of the quinone. The linear equation E(o') = -0.294 - 0.032 pH was found, showing that the pH used (7.0-7.8) did not affect significantly the AQDS determination by CV and AHQDS was the predominant hydroquinone formed. A calibration curve was obtained by plotting current response versus AQDS concentration with a linear correlation (r = 0.999) from 0.2 to 10 mM of AQDS. This technique was applied in a denitrifying culture to establish kinetic profiles for AHQDS formation coupled to acetate and p-cresol oxidation. CV results showed that organic matter oxidation by the denitrifying sludge was stoichiometrically associated to AQDS reduction into AHQDS-. CV was shown to be a useful tool for monitoring oxidation/reduction processes of quinones occurring in complex microbial media.

Batch nitrifying cultures in presence of mixtures of benzene, toluene, and m-xylene.

Benzene, toluene, and m-xylene compounds in individual (5.0 +/- 0.5 mg C l(-1)) and mixed solutions (2.5 +/- 0.2 mg C l(-1) for each one) in nitrifying batch cultures induced a decrease in the specific rates of NH4+ consumption (81 +/- 6%) and NO3- production (39-79%). However, after 24 h, ammonium consumption efficiency and conversion of consumed NH4+ -N into NO3- -N were close to 100% and there was no significant accumulation of nitrite in the medium. After 24 h, no aromatic intermediate was detected in the cultures and 50% of the mixed compounds was converted to acetate. The following order of biotransformation was found: m-xylene > toluene > benzene. Transformation rate of m-xylene was 0.051 +/- 0.005 g C (g protein-N h)(-1) in individual and mixed solutions. When m-xylene was added, benzene was oxidized at a faster rate (0.051 +/- 0.005 g C (g protein-N h)(-1)) whereas toluene at a slower rate (0.012 +/- 0.002 g C (g protein-N h)(-1)).

Simultaneous nitrification and p-cresol oxidation in a nitrifying sequencing batch reactor.

The tolerance, kinetic behavior and oxidizing ability of a nitrifying sludge exposed to different initial concentrations of p-cresol (25-150mg/l) were evaluated in a sequencing batch reactor (SBR) fed with 200mg NH(4)(+)-N/ld. The nitrifying SBR operated up to 300mg/ld of p-cresol, achieving simultaneously the complete ammonium oxidation to nitrate and the total consumption of p-cresol and its transitory intermediates from the culture. p-Cresol induced a significant decrease in the values for specific rates of ammonium consumption, showing that the ammonium oxidation pathway was mainly inhibited. After 7 months of operation in SBR, the specific rates of NH(4)(+)-N oxidation, NO(3)(-)-N formation, and total organic carbon consumption were 0.6g NH(4)(+)-N/g microbial protein-Nh, 0.3g NO(3)(-)-N/g microbial protein-Nh, and 0.24g total organic carbon/g microbial protein h, respectively. The microbial growth rate was always low (maximum value of 12.2+/-0.4mg protein-N/ld) and settleability of the sludge was good with sludge volume index values lower than 21ml/g. The oxidation of p-cresol and its intermediates was carried out faster throughout the cycles and nitrification inhibition decreased with the number of cycles.

[Health behaviours of students at the University Institute of Technology in Poitiers]. / Comportements de santé des étudiants d'IUT de l'Iniversité de Poitiers.

Better knowledge and understanding of students' health attitudes and behaviours are necessary to more effectively plan targeted prevention strategies. A survey conducted among 617 students at the University Institute of Technology in Poitiers showed that although some indicators affirm good health (relationships with friends and family, appropriate contact with care providers in the health system and regular visits to prevention centres, sexual life, and sports and physical fitness), other indicators reveal a certain amount of suffering among the student population. Students reported suicidal thoughts, symptoms of poor well-being (fatigue, sleeping disorders, concentration problems, sadness or depression) and poor eating habits and/or eating disorders. Consumption of both legal and illegal products seems to be a means utilised to facilitate the social integration process for some students. Therefore, this underlines a significant challenge for prevention campaigns to develop an alternative role model, which promotes the image and profile of a healthy student, with a strong sense of self-esteem, who is well-integrated with his peers without having to engage in substance abuse.

Kinetic and metabolic study of benzene, toluene and m-xylene in nitrifying batch cultures.

The effect of benzene, toluene, and m-xylene (BTX) compounds on the nitrifying activity of a sludge produced in steady-state nitrification was evaluated in batch cultures. Benzene and m-xylene at 10 mg C/L decreased ammonium consumption efficiency by 57% and 26%, respectively, whereas toluene did not affect the ammonium oxidation process. The consumed NH4+-N was totally oxidized to NO3- -N. There was no significant effect at 5 mg C/L of each aromatic compound. BTX (5-20mg C/L) induced a significant decrease in the values for specific rates of NH4+ -N consumption (76-99%) and NO3- -N production (45-98%). At 10 mg C/L of BTX compounds, the inhibition order on nitrate production was: benzene > m-xylene > toluene while at 20 mg C/L, the sequence changed to m-xylene > toluene > benzene for both nitrification inhibition and BTX compounds persistence. At 5 mg C/L of BTX compounds, there was no toxic effect on the sludge whereas from 10 to 50 mgC/L, bacteria did not totally recover their nitrifying activity. At a concentration of 5 mg C/L, toluene was first oxidized to benzyl alcohol, which was later oxidized to butyrate while m-xylene was oxidized to acetate and butyrate.

Settleability and kinetics of a nitrifying sludge in a sequencing batch reactor.

A physiological study of a nitrifying sludge was carried out in a sequencing batch reactor (SBR). Pseudo steady-state nitrification conditions were obtained with an ammonium removal efficiency of 99% +/- 1% and 98% +/- 2% conversion of NH4+-N to NO3 - -N. The rate of biomass production was negligible (1.3 +/- 0.1 mg microbial protein-N.L(-1).d(-1)). The sludge presented good settling properties with sludge volume index values lower than 20 mL.g(-1) and an exopolymeric protein/carbohydrate ratio of 0.53 +/- 0.34. Kinetic results indicated that the nitrifying behavior of the sludge changed with the number of cycles. After 22 cycles, a decrease in the specific rate of NO3- -N production coupled with an increase in the NO2- -N accumulation were observed. These results showed that the activity of the nitrite oxidizing bacteria decreased at a longer operation time. Ammonia oxidizing bacteria were found to exhibit the best stability. After 4 months of operation, the specific rates of NH4+-N consumption and NO3- -N production were 1.72 NH4+-N per microbial protein-N per hour (g.g(-1).h(-1)) and 0.54 NO3- -N per microbial protein-N per hour (g.g(-1).h(-1)), respectively.

Benzene transformation in nitrifying batch cultures.

The effect of benzene on the nitrifying activity of a sludge produced in steady-state nitrification was evaluated in batch cultures. Benzene at 10 mg/L inhibited nitrate formation by 53%, whereas at 5 mg/L there was no inhibition. For initial benzene concentrations of 0, 7, and 10 mg/L, the specific rates of NO(3)(-)-N production were 0.545 +/- 0.101, 0.306 +/- 0.024, and 0.141 +/- 0.010 g NO(3)(-)-N/g microbial protein-N.h, respectively. The specific rates of benzene consumption at 7, 12, and 20 mg/L were 0.034 +/- 0.003, 0.050 +/- 0.006, and 0.027 +/- 0.002 g/g microbial protein-N.h, respectively. Up to a concentration of 10 mg/L, benzene was first oxidized to phenol, which was later totally oxidized to acetate. Benzene at higher concentrations (20 and 30 mg/L) was converted to intermediates other than acetate, phenol, or catechol. These results suggest that this type of nitrifying consortium coupled with a denitrification system may have promising applications for complete removal of nitrogen and benzene from wastewaters.

Rare earth elements removal by microbial biosorption: a review.

This paper reviews published work on the sorption of rare earth elements by microbial biomass. In a first part, the biosorption capacities and the various experimental conditions performed in batch reactor experiments are compared. Secondly, sorption modelling generally used in biosorption studies are described. Thirdly, the microbial cell wall characteristics of the metallic ion binding sites are considered. From these observations it seems that the important functional groups for metallic ion fixation are the carboxyl and the phosphate moieties. Moreover, the competing effect of various ions like aluminium, iron, glutamate, sulphate etc. is described. Finally, some adsorption results of the rare earth elements in dynamic reactors are presented.

Fixed-bed study for lanthanide (La, Eu, Yb) ions removal from aqueous solutions by immobilized Pseudomonas aeruginosa: experimental data and modelization.

A fixed-bed study was carried out by using cells of Pseudomonas aeruginosa immobilized in polyacrylamide gel as a biosorbent for the removal of lanthanide (La, Eu, Yb) ions from aqueous solutions. The effects of superficial liquid velocity based on empty column, particle size, influent concentration and bed depth on the lanthanum breakthrough curves were investigated. Immobilized biomass effectively removed lanthanum from a 6 mM solution with a maximum adsorption capacity of 342 micromolg(-1) (+/-10%) corresponding closely to that observed in earlier batch studies with free bacterial cells. The Bohart and Adams sorption model was employed to determine characteristic parameters useful for process design. Results indicated that the immobilized cells of P. aeruginosa enable removal of lanthanum, europium and ytterbium ions from aqueous effluents with significant and similar maximum adsorption capacities. Experiments with a mixed cation solution showed that the sequence of preferential biosorption was Eu3+ > or = Yb3+ > La3+. Around 96+/-4% of the bound lanthanum was desorbed from the column and concentrated by eluting with a 0.1 M EDTA solution. The feasibility of regenerating and reusing the biomass through three adsorption/desorption cycles was suggested. Neural networks were used to model breakthrough curves performed in the dynamic process. The ability of this statistical tool to predict the breakthrough times was discussed.

[Ligamentoplasty of the anterior cruciate ligament after 40 years: a series of 41 patients]. / Reconstruction du ligament croisé antérieur après 40 ans: a propos de 41 cas.

PURPOSE OF THE STUDY: Ligamentoplasty for tears of the anterior cruciate ligament (ACL) is generally thought to be unreliable after the age of 40 years. The purpose of this retrospective analysis was to assess the five-year outcome after ACL plasty in patients aged over 40 at the time of surgery. MATERIAL AND METHODS: Between 1990 and 1997, 41 patients aged 44.5 +/- 4.5 years (28 men, 25 right side) underwent intra-articular reconstruction of the ACL. Clinical and radiological assessment using the IKDC criteria was obtained at a mean 62 months postoperatively using manual instrumental measurements with KT-1000. The indication for reconstruction was instability in daily life activities for 40 patients and difficulties encountered in sports activities in one; there were three cases of remodeling. Arthroscopy was used in all cases to perform a patellar tendon graft (bone-tendon-bone in 30 cases associated with extra-articular lateral reinforcement in eleven). RESULTS: There were no significant complications. Among 12 patients who initially participated in competition sports, seven were able to resume their activity at their former level. At last follow-up, global IKDC score was A for 12, B for 25, and C for three and D for one. All patients scored C or D had a poor IKDC symptom score, basically because of pain. Motion was not modified. The IKDC radiology score was A for 25, B for 15 and C for one, but the three cases of remodeling did not progress. Prognostic factors for overall IKDC result were: age of the patient at the time of reconstruction (under 45 years), and the delay to surgery for accident victims (less than one year). The following criteria had no effect at last follow-up: gender, sport practiced, type of initial laxity (anterior alone or global anterior), presence of meniscal damage, preservation of the medial and/or lateral meniscus, chondral injury observed peroperatively, and use of a lateral reinforcement. Radiographic remodeling observed in this group of 41 patients was related to delay from accident to surgery (p=0.0007) and preservation of the medial meniscus (p=0.03). Age, gender, type of activity before surgery, degree of initial and residual laxity had no statistically significant effect on remodeling. CONCLUSION: Age over 40 years is not a contraindication for arthroscopic free patellar tendon graft for the treatment of chronic anterior laxity. Using rigorous preoperative assessment criteria (delay from accident to surgery, absence of joint space narrowing on the AP and lateral view before intervention, symptomatic instability in daily life activities and motivated patient) this type of procedure can be performed safely and provides good functional outcome at five years. The current follow-up is insufficient to judge potential joint degradation. Age is not a contraindication if certain precautions are taken.

Arthroscopic medial meniscectomy on stable knees.

We reviewed 74 partial medial meniscectomies in 57 patients with stable knees, to assess the long-term functional and radiological outcome. The International Knee Documentation Committee score and the residual laxity were assessed in both knees. At the time of surgery the mean age of the patients was 36 +/- 11 years and the mean follow-up was 12 +/- 1 years. All had a limited medial meniscectomy. The anterior cruciate ligament was intact in all cases. The meniscal tear was vertical in 95% and complex in 5%. The posterior part of the meniscus was removed in 99%. A peripheral rim was preserved in all cases. After 12 years 95% of the patients were satisfied or very satisfied with their knee(s). Objectively, 57% had grade A function and 43% were grade B. The outcome correlated only with the presence of anterior knee pain at final follow-up. In the 49 cases of arthroscopic meniscectomy for which there was a contralateral normal knee there was narrowing of the 'joint-space' in 16% of the operated knees. There was no correlation between this and other parameters such as age or different meniscal pathologies.

[Arthroscopy-assisted revision in failed reconstruction of anterior cruciate ligament: 32 cases]. / Reconstruction itérative du ligament croisé antérieur sous arthroscopie.

PURPOSE OF THE STUDY: The aim of this retrospective study was to analyze mid-term outcome after anterior cruciate ligament (ACL) revision performed arthroscopically with a patellar tendon graft. MATERIAL AND METHOD: The series included 32 revision arthroscopies for ligamentoplasties of the ACL performed after primary intraarticular plasty. Outcome was assessed using the IKDC score at least 2 years after revision surgery. A free patellar autograft was used in all cases in association with an anterolateral plasty in 9 cases using the Marshal-MacIntosh technique. There were 25 men, mean age 28.5 years. Mean follow-up was 4 years. The initial plasty was done with a synthetic ligament in 15 cases and an autograft in 17, including 12 patellar tendons. In 3 cases, the revision was needed for synovitis involving the synthetic ligament. In all the other cases, revision was indicated for instability, most of the failures resulting from a defective femoral position (particularly for autografts) or renewed trauma. RESULTS: Among the 23 patients who were initially competition-level athletes, 18 recovered their sports activity, 8 at an equivalent level. At last follow-up, the IKDC global scores were: A 5 patients (15.6%), B 16 patients (50%), C 8 patients (25%), D 3 patients (9.4%). Certain residual laxity was present in 3 cases (C and D laxity score for 2 of them). A tibiofemoral narrowing was present in the medial compartment in one patient alone. Factors of poor prognosis for the IKDC score were: long delay from accident to initial treatment (p=0.04), associated medial meniscectomy (p=0.02). Presence of an initial femoral tunnel had no effect on revision due to its very anterior situation. DISCUSSION: The technical difficulty of revision of an intra-articular ligamentoplasty of the ACL is to position the new transplant so it will satisfy the same requirements as the initial plasty. This position depends particularly on the femoral component due to the importance of the position of the initial femoral tunnel and the degree of bone loss (osetolysis, ablation of an interfering screw.). The homolateral patellar tendon was used for the graft in all cases except one and iterative use of the patellar tendon for grafting did not cause supplementary morbidity. The patellar tendon remains the transplant of choice for ligament reconstruction. Meniscectomy had a deleterious effect on the final outcome. As for first intention plasty, the therapeutic strategy should preserve as much meniscal stock as possible, depending on the type and degree of damage. CONCLUSION: Revision ACL plasty can provide good anatomic results although functional outcome is less satisfactory than after primary intention ligamentoplasty. A precise clinical and radiographic analysis of the cause of failure of the primary plasty must be obtained in order to establish a surgical strategy allowing the most clinically effective plasty with well positioned bone tunnels.