Understanding of the mechanism of crystal violet adsorption on modified halloysite: Hydrophobicity, performance, and interaction

Halloysite was processed at 600 °C and then by acid leaching with HCl solutions of different concentrations, i.e. 0.5, 3 and 5 N (H600-xN; x = 0.5, 3 or 5). The resulting materials underwent chemical, textural, and laser diffraction analyses and were used in crystal violet (CV) adsorption. Bath experiments were conducted to evaluate the parameters influencing adsorption. A hydrophobicity study by adsorption of water/toluene and a spectroscopic investigation by FTIR and Raman were conducted, to understand the interaction mechanism. The affinity for CV is as follows: H600-0.5N (115 m²g^-1) > H600-3N (434 m²g^-1) > H600-5N (503 m²g^-1) > H600-0N (61 m²g^-1). The maximum adsorption of H600-0.5N would be explained by optimal hydrophilic and hydrophobic properties. Dealumination leads to the creation of more silanols responsible for hydrophilicity. Dehydroxylation at 600 °C combined with dealumination would induce a partial transformation of silanols into siloxanes which are responsible for organophilicity. The CV-H600-0.5N interaction implies two mechanisms: hydrophobic interactions and hydrogen bond. This study focused on hydrophobic interaction as a non-negligible component governing the interaction of organic contaminants with 1:1 clay minerals, while it was not sufficiently considered in the scientific literature.

The two stages surgery in the management of central neurocytoma

Central neurocytoma is an uncommon benign tumour of the central nervous system. The intraventricular location close to the Monro foramina and the attachment to septum pellucidum are characteristics for diagnosis. The encasement of vascular structures represents a surgical challenge. We report a series of 10 cases of central neurocytoma operated at our department 06 of those was operated in two stages intentionally in order to avoid post-operative complications and to obtain complete removal.

The two stages surgery in the management of central neurocytoma

Central neurocytoma is an uncommon benign tumour of the central nervous system. The intraventricular location close to the Monro foramina and the attachment to septum pellucidum are characteristics for diagnosis. The encasement of vascular structures represents a surgical challenge. We report a series of 10 cases of central neurocytoma operated at our department 06 of those was operated in two stages intentionally in order to avoid post-operative complications and to obtain complete removal.

Surgical management of intramedullary spinal cord metastasis

Intramedullary spinal cord metastasis (IMSCM) is a rare complication of malignancies still studied by case reports; although surgery is related with the best results, the management is still debated considering the risks and the low life expectancy; in fact, many authors prefer conservative management (radiotherapy, chemotherapy), and so less than 200 cases reported in the literature with patients IMSCM were treated surgically; reporting such cases will help to understand the pathology and elaborate a clear management protocol. We report three cases of IMSCM operated at our department; in those patients, the intramedullary lesions revealed the primary tumours.    

Early diagnosis and management of traumatic dura tear with brachial plexus injury without spinal lesions in childhood

Although the dura is a thick membrane, it could be severed in spine surgery and less frequently by a traumatism (7,8,10); in this case, it is usually accompanied with bone or ligamentous injury (2). Rare cases are reported of a traumatic dura tear without spinal lesion and would suspect in the first place a brachial plexus injury (2,8). Dura tears are rarely seen in childhood (3). We report a case of early diagnosis of dura tear in brachial plexus injury without bone or ligamentous lesions on a child of 4 years old and we discuss the diagnostic and treatment modalities.

A giant occipital encephalocele

Occipital encephalocele is a rare congenital anomaly that is characterized by herniation of brain tissue through a defect in the skull. Because of their enormous size, they pose a surgical challenge. Occipital encephalocele is the commonest of all encephalocele; the management of encephalocele defects requires immediate surgical closure. The author reports a case of a five months old female baby who presented a progressively increasing swelling over the occipital region. This swelling was present since birth. Surgery was planned to reduce the size of the swelling as well as its contents. The sac was excised and reduced sufficiently enough to accommodate the healthy-looking brain tissue. This infant did well postoperatively.

Subdural Hematoma Complicating Ventriculoperitoneal Shunts: An Algerian Centers Experience

Introduction Subdural hematoma can occur as a complication of a ventriculoperitoneal shunt (VPS), and it should be considered in any patient who present a shunt dysfunction or who does not show the expected recovery after revision of a shunt. Computed tomography (CT) scan is a quick and easy way of detecting subdural hematoma.

Materials and Methods We conduct a retrospective study of 17 patients. All of them are admitted for a subdural hematoma on a VPS. The diagnosis in 13 cases is made by CT scan; three cases by brain MRI.

Results We operated 16 patients and the evacuation of the hematoma with revision of the shunt was performed; we used an adjustable shunt for three patients and endoscopic third ventriculostomy in one case. The operative outcomes were favorable in 12 patients; there were 4 recurrences, 2 of which required evacuation of the hematoma through a bone flap.

Conclusion The subdural hematoma is a complication observed during the surgical treatment of the hydrocephalus and can be a serious issue. We suggest that a brain CT scan should be routinely performed in symptomatic patients with VPS.

Resection of giant invasive thoracic schwannoma

Even though spinal nerve sheath tumours, presented especially by schwannomas, are considered to be mostly benign; they can gain a huge size and have an invasive behaviour, causing spinal cord compression, bone destruction, and make the total removal of the tumour a real challenge for the surgeon. This type of tumours is recently described as giant invasive spinal schwannoma (GISS), this type rarely reported in the thoracic region; deserve a special studying vis-a-vis the diagnosis and the management of both the tumour and the bone destruction.        

Treatment of chronic pain by spinal cord stimulation

Failed back surgery syndrome (FBSS) is often used to describe the condition of patients who have experienced continued pain after surgery. It is of multifactorial genesis and may be the consequence of various lumbar spinal diseases; lumbar disc herniation surgery or spinal canal stenosis laminectomy. The presented series included 13 patients affected with chronic pain related to FBSS who underwent implantation of spinal cord stimulation. The mean percentage of pain relief was 90 % for all patients. 60% of the patients were in a better psychological status and the intake of analgesic medications has been reduced of more than 70%. More than 50% of the patients could resume professional activities. Analysis of the risks and benefits comes in favour of spinal cord stimulation.

Communicating spinal epidural thoracic arachnoid cyst en-bloc resection

Background: Spinal extradural arachnoid cyst is an uncommon, expanding lesion which may communicate with the subarachnoid space, The etiology still remains unclear, but the most accepted explanation is the existence of areas of weakness in the spinal dura , Spinal arachnoid cysts are usually in the thoracic spine, and they may cause symptoms due to spinal cord compression. Case Presentation: Patient is a 54-years-old female who presented with progressive back pain and motor deficit, Magnetic resonance imaging (MRI) study revealed an extradural cyst extending from T2 to T4 isointense with the cerebrospinal fluid (CSF) on all sequences and did not enhance on T1-weighted post-contrast MRI. Patient underwent T2-T4 laminectomy, en-bloc resection of the lesion was achieved and the histopathological examination objectified an arachnoid cyst. Conclusion: Spinal extradural arachnoid cyst can cause neurologic deficit and the mainstay of treatment in patients with neurological symptoms is surgical removal of the cyst together with ligation of the communicating pedicle and closure of the dural defect.

Skull metastasis of hepatocellular carcinoma in normal liver

Background: So far hepatocellular carcinoma (HCC) is the most common liver malignant tumour; it is rarely encountered on a healthy liver (9). The metastasis from HCC cancer are seen in lymph nodes (16%–40%) and lungs (34%–70%), (1,3,4,5,7,8), bone metastasis is unusual and some locations stay rare among them the skull (2,4,5). We report here a case of a patient operated in our department for skull metastasis. That patient was followed for hepatocellular carcinoma in digestive surgery department. Case presentation: The patient is a 57 years old male presenting HCC on healthy liver, the patient was referred to our department by digestive surgery colleagues to manage a parietal subcutaneous mass; brain CT scans were performed objectified a calvarial osteolytic process. We remove the tumour and we put a cranioplasty using surgical cement, later the histological studies were in favour of secondary location of hepatocellular carcinoma. Conclusion: Skull metastasis from hepatocellular carcinoma is rare, reporting such cases strengthen the idea of evoking HCC metastasis in the differential diagnosis of cranial subcutaneous mass.

Ewing’s sarcoma of the mobile spine

Background. Ewing’s sarcoma is a bony highly malignant tumour, it occurs most frequently in the second decade of life. Ewing’s sarcoma is a rare affection, located usually in the pelvis, the femur, the humerus, the ribs, the mandible and clavicle, other location are rare especially in the spine. We report three cases of spinal Ewing’s sarcoma, two primary spine locations and one on young adult with unusual clinical presentation. Cases presentation Case 1. The first patient is a girl of 14 years old without past medical history. She presented initially two months before consultation a neck pain followed days after by a weakness of the left upper limb; the spine imaging performed objectified a destructive process of C2 with a spinal cord compression. The patient was operated beneficiating of a spinal cord decompression and a subtotal removal of the tumour. The pathologist’s results were in favour of Ewing’s sarcoma and the patient was oriented to oncology. Case 2. The second patient is a man of 31 years old operated five years before he consulted for shoulder Ewing’s sarcoma followed by chemotherapy and radiotherapy, he presented two months before consultation a cauda equina syndrome. Spine MRI objectified a double location of an epidural tumour at T3-T4 and S1-S2 levels. The patient was operated beneficiating of subtotal removal of the tumour. The laboratory exam results were in favour of Ewing’s sarcoma and the patient was oriented to oncology. Case 3. The third patient is a 6 years old boy who presented a 1 month history of low back pain followed by a rapidly deteriorating weakness of both lower limbs over a weak. On examination there was bilateral spastic paraplegia, hypoesthesia below the level of Th10 and a urinary retention. The MRI imaging revealed a lesion on the levels Th8, Th9 and Th10 vertebras involving the body, pedicle, lamina, and the transverse process on the left side with an epidural invasion compressing the spinal cord. The tumour was radically removed. Pathology report was in favour of Ewing’s sarcoma. Two weeks after surgery the patient was able to walk. He was referred for adjuvant systemic chemotherapy. Conclusion. Ewing’s sarcoma is rare malignant tumour. The location in the spine exposes the patient to more complications because of the neurostructures compression. The surgical total removal followed by radio and chemotherapy is the only option with the best prognostic and guaranties an acceptable life quality.

Spinal epidural angiolipoma causing spinal cord compression

Background. Spinal angiolipoma (SAL) is a rare tumour with double component mature adipose tissue and proliferating abnormal blood vessels, which result in spinal cord compression requiring an urgent surgical removal. We report a case of woman with spinal angiolipoma. Case presentation. The patient is a 26 years old woman with past medical history of a low grade urothelial bladder carcinoma removed 4 months before she consults at our department, 2 months later the patient presented a lower limbs weakness. The clinical exam at the admission found a patient with paraparesis, hypoesthesia at the level of Th4 and urinary urgency. The spinal MRI objectified a spinal cord compression by a lesion located at the epidural space from Th2 to Th4. The patient was operated and a fatty well vascularized tumour distinct from the epidural fat was removed through a Th2 to Th4 laminectomy. The pathology study was in favour of an angiolipoma. Days after the operation the patient recovered totally, the weakness and the urinary urgency disappeared. The patient is flowed since 24 months she got pregnant. Conclusion. Spinal angiolipoma is a rare tumour with a clinic of spinal cord compression, MRI is the gold standard in diagnosis it shows a fatty lesion with a large enhancement, surgery is the perfect treatment with good outcome and exceptional recurrence.

Development and characterization of a new dolomite-based catalyst: application to the photocatalytic degradation of pentachlorophenol

The development of new catalysts from abundant raw materials, generating attractive photocatalytic activity, constitutes a real challenge in the context of sustainable development concerns. In this setting, a dolomite was treated at 800 °C (D800) and then chemically modified by Ca(NO₃)₂ (CaD800) using a simple procedure. The resulting materials were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy (EDS), solid state UV spectroscopy, and used as catalysts of pentachlorophenol (PCP) degradation in aqueous solutions under UV light irradiation. The treatment of dolomite at 800 °C enabled a full decarbonation of CaMg(CO₃)₂, with formation of CaO, Ca(OH)₂, and MgO. Additional CaO was generated after chemical treatment as revealed by EDS analysis; the Ca/Mg ratio increased from 1.29 (D800) to 1.44 for CaD800. This CaO in aqueous medium hydrates by giving Ca(OH)₂. CaD800 was found to be the best photocatalyst with a PCP degradation rate of 95% after only 1 h of treatment, for a CaD800/D800 degradation rate constant ratio of 1.58. In this regard, we investigated the Fourier transform infrared spectra of CaD800, PCP, and CaD800 loaded with PCP after degradation. We thus evidenced the involvement of Ca(OH)₂ in the PCP degradation process. Catalytic activity was discussed through the contribution of OH radicals and electrodonation.

Degradation of EDTA in H2O2 -containing wastewater by photo-electrochemical peroxidation

Semiconductor wastewater currently contains H₂O₂ which is an important reagent in wafers cleaning. Recalcitrant organic pollutant such as EDTA are always present in this type of wastewater and may represent a threat for the environment. In this work, a new photoelectrochemical reactor is proposed to remove EDTA from H₂O₂ contaning wastewater. First, photolysis, electrochemical peroxidation and photo-electrochemical peroxidation were compared. The results showed that the removal efficiency decreases in the sequence: UV/H₂O₂ «EC/H₂O₂ <UV/EC/H₂O₂. The main parameters affecting the photo-electrochemical peroxidation process were studied. The study revealed that the optimal current was 50 mA, while the optimum initial pH was found in the acidic range from 2.25 to 3.0, with a peak at 2.25. Increasing H₂O₂ concentration results in increasing in EDTA removal up to 92.1%, while decreasing initial EDTA concentration up to 22.5 mg L^-1 gives a complete removal in only 90 min. It was also found that the degradation of EDTA greatly depends on the nature of the present cation.

Removal of catechol from water by modified dolomite: performance, spectroscopy, and mechanism

Dolomite was treated at 800 °C (D800), characterized, and used in the adsorptive removal of catechol (1,2-dihydroxybenzene) from aqueous solutions. The performances of the D800 sample, named dolomitic solid, were compared with those of the raw material. A bibliographic review shows that the data on the adsorption of phenolic compounds by dolomites are non-existent. Kinetic data, equilibrium isotherms, thermodynamic parameters, and pH influence were reported. Special attention was paid to the spectroscopic study, before and after adsorption. The purpose was to understand the mechanism of catechol uptake on dolomitic materials. Kinetics follows the pseudo-second order model. The Redlich-Peterson isotherm provides the best correlation of our isotherms. Affinity follows the sequence: D800 ≫ raw dolomite. The process is spontaneous at low temperatures and exothermic. After catechol adsorption, the shape of the band in the 3,600-3,000 cm^-1 range and its red shift towards 3,429 cm^-1 reflect a deep involvement of OH groups both of D800 and catechol, which confirm hydrogen bonding via their respective OH. On this basis, a schematic illustration was proposed. The understanding of the phenolic compound-dolomitic solid interactions constitutes a fundamental approach to developing the application of these materials in wastewater treatment.

Removal of fluoride, SDS, ammonia and turbidity from semiconductor wastewater by combined electrocoagulation-electroflotation

Semiconductor industry effluents contain organic and inorganic pollutants, such as sodium dodecyl sulfate (SDS), fluoride and ammonia, at high levels which consists a major environmental issue. A combined EC-EF process is proposed as a post-treatment after precipitation for simultaneous clarification and removal of pollutants. In EC step, a hybrid Fe-Al was used as the soluble anode in order to avoid supplementary EC step. EC-Fe is more suitable for SDS removal; EC-Al is more suitable for fluoride removal, while EC with hybrid Al-Fe makes a good compromise. Clarification and ammonia oxidation were achieved in the EF step. Effects of anodic material, initial pH, current, anion nature, chloride concentration and initial pollutant concentration were studied. The final concentrations may reach 0.27, 6.23 and 0.22 mg L^-1 for SDS, fluoride and ammonia respectively. These concentrations are far lower than the correspondent discharge limits. Similarly, the final turbidity was found 4.35 NTU which is lower than 5NTU and the treated water does not need further filtration before discharge. Furthermore, the EC-EF process proves to be sufficiently energy-efficient with less soluble electrode consumption.

TiO2-assisted degradation of a perfluorinated surfactant in aqueous solutions treated by gliding arc discharge

The plasma-chemical degradation of Forafac 1110, a perfluorinated non-ionic surfactant, in aqueous solutions was investigated using TiO2 catalysts. The considered plasma was the gliding arc in humid air, which results from an electric discharge at atmospheric pressure and quasi-ambient temperature. Two titanium dioxide powders were used and their synergistic effects on the Forafac degradation were compared. The results were discussed through the evolution of the pH, the conductivity, the fluoride ions concentration released in solutions, the surfactant concentration remaining after treatment and the chemical oxygen demand (COD) measurement. The combination of the plasma-chemical treatment with heterogeneous catalysis through the use of TiO2 accelerated the Forafac degradation, since only 60 min was sufficient to remove 96% instead of 360 min needed in the absence of TiO2. The use of anatase and rutile under the trade-name of Rhodia TiO2 and Merck TiO2, respectively, led to different results, because Rhodia TiO2 has proven to be more efficient. It would seem that the crystalline phase as well as the crystallite size, explain the efficiency of anatase. The advantage of the plasma-catalysis is due to the fact that there is a significant production of the OH* radicals not only generated by the gliding arc discharge but also by TiO2.

Removal of pentachlorophenol from aqueous solutions by dolomitic sorbents

The partial decomposition of dolomite carried out within the temperature range 600-1000 degrees C provides new sorbents, called dolomitic sorbents. Their surface properties and identification by X-ray diffraction are discussed. The lowest specific surface area value was found for the raw dolomite, while the highest value was achieved by the D-1000 sample. The adsorption equilibrium of pentachlorophenol from aqueous solutions on the examined sorbents was investigated at 30, 40, and 50 degrees C via a bath process. Langmuir, Freundlich, Langmuir-Freundlich, and Redlich-Petersen models were fitted to experimental equilibrium data, and their goodnesses of fit are compared. The adjustable parameters of Langmuir-Freundlich and Redlich-Petersen isotherms were estimated by nonlinear least-squares analysis. Langmuir and Freundlich models were found insufficient to explain the adsorption equilibrium, while Langmuir-Freundlich and Redlich-Petersen isotherms provide the best correlation of the pentachlorophenol adsorption onto dolomitic sorbents.

[The costs of asthma in France: an economic analysis by a Markov model]

INTRODUCTION

In France about 3.5 million people suffer from asthma, with an estimated annual cost of 1.5 billion euros. Few data on the components of the cost are available. To develop a medico-economic model to identify the mean annual cost of a patient with asthma together with the components of the cost and the consequences of different modalities of management (out-patient and in-patient).

METHODS

A first degree homogeneous Markov model was constructed, based on published data, to identify the different states of health of asthmatic patients, their development and probabilities of change from one to another.

RESULTS

The mean annual cost of asthma is 631 +/- 299 euros; 298 euros for stable patients, 1,052 for those who have at least one acute attack and 3,811 for those hospitalised. Actions leading to better control of the disease in the community (prevention and management of attacks) would produce a larger reduction in mean costs than actions undertaken in patients seen as an emergency or admitted to hospital.

CONCLUSIONS

From the point of view of society better control of asthma in the community is the most effective strategy to reduce expenditure.

Adsorption of carbon dioxide by X zeolites exchanged with Ni2+ and Cr3+: isotherms and isosteric heat

The adsorption of CO2, at intervals of 30 K from 303 K was carried out on M(n+)X zeolites (M(n+)=Ni2+ or Cr3+) exchanged at different degrees. The structural regularity of the zeolite lattice of NaX and the existence of well-defined cavities within which the adsorbate molecules are lodged suggest that it should be possible to use various isotherm equations. Several models were thus used to describe the experimental isotherms. The best fit of adsorption isotherm data is obtained with the Sips model. The Volmer model also describes satisfactorily the isotherms of CO2 adsorption by NaX, Ni(x)X, and Cr(x)X. Analysis of the isosteric heat reveals a character energetically heterogeneous for NaX and Ni(x)X samples exchanged at a higher degree of Ni2+ exchange and at low coverage. Specific interaction is also obtained between the adsorbate molecules and Cr(x)X exchanged at a lower degree. From these considerations, hypotheses will be advanced to describe the behavior of the adsorbed phase within zeolitic cavities.