Cation exchange capacity of biochar: An urgent method modification

Biochar, produced through pyrolysis of organic matter, is negatively charged, thus contributing to electrostatic adsorption of cations. However, due to its porous structure and contents of alkaline ashes, the determination of the cation exchange capacity (CEC) is challenging. Literature values for the CEC of biochar are surprisingly variable and are often poorly reproducible, suggesting methodological problems. Here, we modify and critically assess different steps in the existing ammonium acetate (NH₄OAc) method (pH 7), where ammonium (NH₄⁺) is displaced by potassium chloride (KCl), following removal of excess NH₄OAc with isopropanol, in batch mode. We used pigeon pea biochar to develop the method and conducted a test on three additional biochars with different acid neutralizing capacity. A pretreatment step of biochar was introduced, using diluted hydrochloric acid, to decrease biochar pH to near neutral, so that 1 M NH₄OAc effectively buffers the biochar suspension pH at 7. This allows the CEC of all biochars to be determined at pH 7, which is crucial for biochar comparison. The dissolution of ashes may cause relatively large weight losses (e.g. for cacao shell biochar), which need to be accounted for when computing the CEC of raw biochar. The sum of NH₄OAC-extractable base cations provided a smaller and better estimate of the CEC than KCl-extractable NH₄⁺. We hypothesize that the overestimation of the CEC based on KCl-extractable NH₄⁺ is due to the ineffectiveness of the relatively large isopropanol molecules to remove excess NH₄OAc in biochars rich in micro-pores, due to size exclusion. The amount of base cations removed in the pretreatment was about three (rice husk biochar) to ten times (pigeon pea biochar) greater than the amount of exchangeable cations. The CEC values of biochar increased from 10.8 cmol/Kg carbon to 119.6 cmol/Kg carbon. These values are smaller than reported CEC values of soil organic carbon.

Local control of glomus tumors of the head & neck by radiation therapy and surgery

PURPOSE

Glomus tumors are rare tumors, highly vascular and typically radiosensitive. Therapeutic options include surgery, radiation therapy (RT), embolisation or any combination of them, but the appropriate treatment still remains a challenge. The purpose of this study was to report the results of local control of 7 patients with glomus tumors treated with surgery and external beam RT (EBRT).

METHODS

All of the patients underwent primary surgery and then postoperative EBRT. Follow-up was calculated from the date of initiation of EBRT and ranged from 3 to 15 years (mean 7.14, median 6.2). The likelihood of local control was analysed using the Kaplan-Meier product limit method. We also analysed the average duration of response between two groups of patients with different doses of EBRT as well as the presence of acute and late EBRT complications.

RESULTS

Local control was obtained in 6/7 (85.7%) patients. Moreover, local control was achieved in 3/4 (75%) patients with recurrent glomus tumors, while in patients with postoperative residual disease local control was obtained in 3/3 (100%) of them. Patients who received <50 Gy (n=2) had shorter average duration of response compared to patients who received >50 Gy (n=5; p=0.248). There were no severe treatment complications.

CONCLUSION

Surgery and RT represent an appropriate treatment approach for advanced glomus tumors with acceptable complications.

Functional electrical therapy: retraining grasping in spinal cord injury

OBJECTIVE

To determine the clinical efficacy of functional electrical therapy in the rehabilitation of grasping function for quadriplegics.

STUDY DESIGN

Randomized intervention-versus-control trial.

SETTING

Rehabilitation hospital for spinal cord injury in Toronto, Canada.

METHODS

A total of 21 people with new spinal cord injuries ranging from C3 to C7 were randomly assigned to two groups: Control (N=9) and Intervention (N=12). The intervention was functional electrical therapy, which consisted of repetitive grasping exercises using a neuroprosthesis that applied surface electrical stimulation to the arm to generate and/or assist grasping movements. It was applied by registered Occupational Therapists in a clinical setting. Main outcome measures were: Functional Independence Measure (FIM), Spinal Cord Independence Measure (SCIM), and the Rehabilitation Engineering Laboratory Hand Function Test. Consumer perceptions of functional electrical therapy were assessed via qualitative interviews.

RESULTS

Differences between the Control and Intervention groups could be observed although they are not significant due to an insufficient number of participants. Consumer perceptions were positive, including improved Activities of Daily Living and self-satisfaction.

CONCLUSION

Functional electrical therapy has the potential to be an effective treatment modality to restore grasping function in quadriplegia. It can be implemented by occupational therapists in a clinical setting. Further research is required to establish suitable indications for participant selection. In addition, a larger number of participants is needed to demonstrate statistical significance of the Functional Electrical Therapy.

The basis for splenic segmental dearterialization: a post-mortem study

The anatomical features of splenic segmental vessels in 102 human spleen autopsy specimens were analyzed. Methods applied were corrosion casting and post-mortem arteriography. The superior terminal splenic branch divided extracapsularly into 2.8+/-0.9 (range 2-5) and the inferior terminal splenic branch into 2.3+/-0.75 (range 2-5) branches per sample. The extracapsular lengths of the segmental branches ranged from 4.0 to 16.7 mm and the calibers from 0.4 to 2.2 mm. Superior polar arteries occurred in 31.3% and inferior polar arteries in 20.6% of cases. Their average extracapsular lengths were 39 mm and 31 mm, respectively. In conclusion, segmental splenic arteries have an extrasplenic origin and course, with an average length and caliber that allow surgical access and ligation, in order to achieve segmental dearterialization for hemostasis purposes and splenic preservation.

Is splenic lobe/segment dearterialization feasible for inferior pole trauma during left hemicolectomy?

We discuss splenic salvage by lobe/segment dearterialization, without resection, after intraoperative trauma, and present two cases. We performed a retrospective analysis of 163 patients in whom the colon splenic flexure was mobilized. Patients with ileo-rectal anastomosis or urgent cases were excluded. Surgical operations included left hemicolectomy and anterior resection of the rectum. Splenic procedures were splenorrhaphy, dearterialization and splenectomy. Spleen lesions occurred in 4 (2.45%) cases. One capsular tear was managed with splenorrhaphy. Three mechanical lesions to capsula and tissue of the inferior pole were managed by either splenectomy (the first case) or dearterialization. Overall mortality in the series was 4.3%. Among the patients with splenic procedures, the splenectomized patient died due to pulmonary embolism. The two cases treated by inferior splenic branch and inferior polar artery ligature are presented. In operative trauma to the inferior splenic pole, bleeding can be controlled by lobe/segment dearterialization and by methods of local hemostasis in most cases.

Herpes simplex virus infection in women with previous spontaneous abortion

We have carried out a retrospective clinical investigation of 45 women in the first and second trimester of pregnancy aiming to demonstrate the role of genital HSV infection in the genesis of spontaneous abortion (miscarriage). Latent HSV infection was diagnosed using the microneutralization test; asymptomatic HSV vaginal or cervical shedding was diagnosed with indirect immunofluorescence and cytological-Papanicolau staining. The results showed that the highest incidence of latent HSV type 2 infection (64%) occurred in women who had one or more spontaneous abortions, whereas this type of infection was found in only 5% of pregnant women of the control group. The incidence of asymptomatic cervical HSV type 2 infection was also considerably higher in patients with a history of spontaneous abortions. Our results indicate a possible aetiological connection between HSV and spontaneous abortion.