Nanoscopic insights of saline water in carbon nanotube appended filters using molecular dynamics simulations

Nanotube appended membranes are shown to be very promising due to their ultrafast water transport and very high salt rejection ability. Using classical molecular dynamics, the present study reports the nanoscopic assessment of various molecular events for nanotube-based desalination, which might be useful for nanoscale devices during process operation at the macroscopic scale. The characteristics of water and ion flow are discussed with varied strength of pressure gradient and salt concentration for different scales of confinement. The results revealed that the membranes comprising nanotubes of 1.0-1.1 nm diameter can be optimized for efficient water desalination with more than >95% salt rejection. Furthermore, the anomalies in water flux through nanotubes are linked with the hydration characteristics of ions inside CNTs. The results show the maximum hydration of confined ions inside the nanotubes, which indicated the minimum permeability of water due to freezing effects. Furthermore, the MD results revealed that akin to bulk phases, the mass transport through nanotubes can be linked with the component diffusivity in the medium. It has been demonstrated that not only the diffusivities of water and ions, but even the gradient of water to ion diffusivity might be utilized to predict and explore the experimental observations, which might be helpful in optimizing the operational regime in nanotube-based filtrations. Moreover, the thermodynamic characteristics of the flow are discussed in terms of the entropy of water and ions using the robust two-phase thermodynamic (2PT) method. The results reflect that the entropy of water is linked to the distortion of the hydrogen bond network inside the nanotube confinement, at the nanotube-water interface and at the bulk solution, whereas the entropy of ions seems to be majorly dominated by their oscillation. Also, the interconnection of hydration structure, mass flux and the diffusivity of water and ions along with their thermodynamic origin are discussed.

Tuberculosis-diabetes screening: how well are we doing? A mixed-methods study from North India

Setting

Public health care facilities in Sonipat District, Haryana State, India.

Objectives

To assess 1) the proportion of tuberculosis (TB) patients screened for diabetes mellitus (DM) and vice versa, 2) factors associated with screening, and 3) the enablers, barriers and solutions related to screening.

Design

A mixed-methods study with quantitative (cohort study involving record reviews of patients registered between November 2016 and April 2017) and qualitative (interviews of patients, health care providers [HCPs] and key district-level staff) components.

Results

Screening for TB among DM patients was not implemented, despite documents indicating that it had been. Of 562 TB patients, only 137 (24%) were screened for DM. TB patients registered at tertiary and secondary health centres were more likely to be screened than primary health centres. Low patient awareness, poor knowledge of guidelines among HCPs, lack of staff and inadequate training were barriers to screening. Enablers were the positive attitude of HCPs and programme staff. The key solutions suggested were to improve awareness of HCPs and patients regarding the need for screening, training of HCPs and wider availability of DM testing facilities.

Conclusion

The implementation of bidirectional screening was poor. Adequate staffing, regular training, continuous laboratory supplies for DM diagnosis and widespread publicity should be ensured.

Clinical Diversity of CNS Cryptococcosis

BACKGROUND

Though cryptococcal meningitis (CM) is recognized as a disease of the immunocompromised, studies have implicated that it also affect immunocompetent patients.

METHODOLOGY

This was a cross sectional study conducted in the Department of Medicine of a tertiary teaching institution in North India. All the patients diagnosed with CM on the basis of detection of cryptococcal antigen or the presence of capsulated budding yeast cells on India ink preparation, from April 2009 to March2015 were included in the study. Demographical profile, clinical presentation, predisposing factors, CSFcharacteristics, imaging abnormalities and in patient outcome were noted and analyzed.

RESULTS

Among the 40 patients diagnosed with CM, 62.5% of them were males. Patients who were immunocompetent constituted 20%, those with predisposing factors other than HIV were 25% and55% had HIV infection (initial presentation in 59%). Mean age of presentation was 44.75 ± 15.58 years. Mean duration of symptoms in all three groups varied from few days to 4-5 weeks. Clinical presentations included fever (16), headache (14), altered sensorium (16), seizures (5), paraparesis (4), hemiparesis (2), lateral rectus palsy (3), VII nerve palsy (2), bilateral vision loss with ptosis (1) and ataxia (1). Neck stiffness was present in 50% patients of immunocompetent group, 45.45% of HIV patients and none in the 3rd group. Acellular CSF (37.5%) was not unusual. Mean CSF white cell count in HIV patients, in other immunocompromised patients and immunocompetent patients were 100± 158.53, 36.88 ± 92.43 and 32.5 ± 62.05 /mm3 respectively which was predominantly lymphocytic. Mean CSF protein were 136.73 ± 139.82, 62.67 ± 51.11 and 152.29 ± 218.24 g/dl in these groups. Abnormalities detected on imaging included, meningeal enhancement, encephalomalacia, infarct, cerebellitis, hydrocephalus, cord hyper intensities and cervical spine intramedullary lesion. Mortality rate in CM patients was 20%. On mortality analysis, death was mostly attributed to the primary disease.

CONCLUSIONS

Clinical presentation of CM in both immunocompetent and immunocompromised patients was similar. Though previous studies noted less inflammation in immunocompromised patients, in this series it was noted that both immunocompromised and immunocompetent patients mounted similar inflammatory response. Since the presentation of CM is variable, all cases of meningitis should be screened for the same.

1H, 13C, 15N resonance assignment of recombinant Euplotes raikovi protein Er-23

Er-23 is a small, 51 amino acid, disulfide-rich pheromone protein used for cell signaling by Euplotes raikovi. Ten of the 51 amino acids are cysteine, allowing up to five disulfide bonds. Previous NMR work with Er-23 utilized homologously expressed protein, prohibiting isotopic labeling, and consequently the chemical shift assignments were incomplete. We have expressed uniformly ¹⁵N and ¹³C-labeled Er-23 in an E. coli expression system. Here we report the full backbone and side chain resonance assignments for recombinant Er-23.

Cerebrovascular Manifestations of Neurosarcoidosis: An Underrecognized Aspect of the Imaging Spectrum

Involvement of the central nervous system by sarcoidosis, also referred to as neurosarcoidosis, is seen clinically in about 5% of patients with systemic disease. CNS involvement most frequently affects the leptomeninges and cranial nerves, though the ventricular system, brain parenchyma, and pachymeninges may also be involved. Even though the involvement of the intracranial vascular structures is well-known on postmortem studies, there is scant literature on imaging manifestations secondary to the vessel wall involvement, being confined mostly to isolated case reports and small series. The authors present a review of various cerebrovascular manifestations of neurosarcoidosis, along with a brief synopsis of the existing literature.

Molecular Facts on the Structure and Dynamics of Electrolyte Species in Cu-Cl Cycle for Hydrogen Generation: An Insight from Molecular Dynamic Simulations

The Cu complex, which is the key chemical species in well-known Cu-Cl hybrid thermochemical cycles and also in numerous metal hydrometallurgical and sedimentary deposit processes, displays a wide variety of structural and dynamical characteristics that are further complicated by the presence of multiple oxidation states of Cu ions with different coordination chemistries, therefore they are difficult to explore from experiments alone. In this article, an attempt has been made to understand the coordination behavior of the Cu complex using MD simulations. The study provides compelling evidence of the experimentally observed multiple stoichiometries of Cu ions, i.e., 1:6:0, 1:5:1, and 1:4:2 for Cu⁺:H₂O:Cl^- and 1:6:0 for Cu²⁺:H₂O:Cl^-. The presence of the anionic Cu complex, [Cu⁺Cl₂]^-·2H₂O, [Cu⁺Cl₂]^-·3H₂O, [Cu²⁺Cl₃]^-·H₂O, and [Cu²⁺Cl₃]^-·2H₂O, was captured in the presence of excess chloride ions. Furthermore, the probability distribution profiles have been estimated to determine the most possible complex in the considered systems. The results establish structural and dynamical reformation of the Cu complex with change in the salt concentration or variation in the solvent medium in which they are dissolved. Moreover, the structure and kinetics of the Cu ions in the Cu-Cl electrolyzer have been explored over a large range of the electric field by extending the simulated systems for varied strengths of the electric fields. It has been observed that with an increase in the strength of the electric field, the water molecules lose their coordination strength with central Cu ions, which, on the other hand, results in a significant change in the structure of the captured complex. The diffusion dynamics of the ions is altered while applying the electric field, which is furthermore modified while increasing the strength of electric field beyond a critical limit. In fact, the diffusion mechanism of the ions was seen to be transformed from Brownian-like to linear motion and then to hopping diffusion with the increasing strength of the electric field. To the best of our knowledge, this is the first time when the multiple oxidation states of the Cu ion are explored using MD simulations, and the coexisting pictures of the multiple coordinations and the solvent effects have been clearly revealed. Also to date, the present article is the first one to report the insights of the structure and the dynamics of the ions in the Cu-Cl electrolyzer over a wide range of the electric field. The present studies will be very helpful in understanding the mechanism involved in numerous metal hydrometallurgical and sedimentary deposit processes and to comprehend the analogies involved in the electrode reactions of the Cu-Cl cycle for hydrogen generation.

Dynamic Contrast-Enhanced MRI-Derived Intracellular Water Lifetime (τ i ): A Prognostic Marker for Patients with Head and Neck Squamous Cell Carcinomas

BACKGROUND AND PURPOSE

Shutter-speed model analysis of dynamic contrast-enhanced MR imaging allows estimation of mean intracellular water molecule lifetime (a measure of cellular energy metabolism) and volume transfer constant (a measure of hemodynamics). The purpose of this study was to investigate the prognostic utility of pretreatment mean intracellular water molecule lifetime and volume transfer constant in predicting overall survival in patients with squamous cell carcinomas of the head and neck and to stratify p16-positive patients based upon survival outcome.

MATERIALS AND METHODS

A cohort of 60 patients underwent dynamic contrast-enhanced MR imaging before treatment. Median, mean intracellular water molecule lifetime and volume transfer constant values from metastatic nodes were computed from each patient. Kaplan-Meier analyses were performed to associate mean intracellular water molecule lifetime and volume transfer constant and their combination with overall survival for the first 2 years, 5 years, and beyond (median duration, >7 years).

RESULTS

By the last date of observation, 18 patients had died, and median follow-up for surviving patients (n = 42) was 8.32 years. Patients with high mean intracellular water molecule lifetime (4 deaths) had significantly (P = .01) prolonged overall survival by 5 years compared with those with low mean intracellular water molecule lifetime (13 deaths). Similarly, patients with high mean intracellular water molecule lifetime (4 deaths) had significantly (P = .006) longer overall survival at long-term duration than those with low mean intracellular water molecule lifetime (14 deaths). However, volume transfer constant was a significant predictor for only the 5-year follow-up period. There was some evidence (P < .10) to suggest that mean intracellular water molecule lifetime and volume transfer constant were associated with overall survival for the first 2 years. Patients with high mean intracellular water molecule lifetime and high volume transfer constant were associated with significantly (P < .01) longer overall survival compared with other groups for all follow-up periods. In addition, p16-positive patients with high mean intracellular water molecule lifetime and high volume transfer constant demonstrated a trend toward the longest overall survival.

CONCLUSIONS

A combined analysis of mean intracellular water molecule lifetime and volume transfer constant provided the best model to predict overall survival in patients with squamous cell carcinomas of the head and neck.

Effect of Replacing Race With Apolipoprotein L1 Genotype in Calculation of Kidney Donor Risk Index

Renal allografts from deceased African American donors with two apolipoprotein L1 gene (APOL1) renal-risk variants fail sooner than kidneys from donors with fewer variants. The Kidney Donor Risk Index (KDRI) was developed to evaluate organ offers by predicting allograft longevity and includes African American race as a risk factor. Substituting APOL1 genotype for race may refine the KDRI. For 622 deceased African American kidney donors, we applied a 10-fold cross-validation approach to estimate contribution of APOL1 variants to a revised KDRI. Cross-validation was repeated 10 000 times to generate distribution of effect size associated with APOL1 genotype. Average effect size was used to derive the revised KDRI weighting. Mean current-KDRI score for all donors was 1.4930 versus mean revised-KDRI score 1.2518 for 529 donors with no or one variant and 1.8527 for 93 donors with two variants. Original and revised KDRIs had comparable survival prediction errors after transplantation, but the spread in Kidney Donor Profile Index based on presence or absence of two APOL1 variants was 37 percentage points. Replacing donor race with APOL1 genotype in KDRI better defines risk associated with kidneys transplanted from deceased African American donors, substantially improves KDRI score for 85-90% of kidneys offered, and enhances the link between donor quality and recipient need.

Neurosensory evaluation of inferior alveolar nerve after bilateral sagittal split ramus osteotomy of mandible

Mandibular skeletal deformities are mostly corrected by Sagittal Split Ramus Osteotomy. One of the main complications of Bilateral Sagittal Split Ramus Osteotomy is impairement of sensory function of Inferior Alveolar Nerve.

OBJECTIVES

To evaluate the occurrence of neurosensory disturbance by comparing the subjective and objective assessment of neurosensory responses after bilateral sagittal split ramus osteotomy.To assess the progress of recovery from the first post operative day till six months. To explain the factors causing neurosensory disturbances.

METHOD

A series of 24 patients with clinically and radiographically diagnosed mandibular skeletal deformity were treated with Bilateral Sagittal Split Ramus Osteotomy. For evaluation of the neurosensory responses, the parameters consist of subjective and objective test in order to compare the subjective and objective assessment.

RESULTS

On the first post operative day neurosensory disturbances were seen in all the patients. Recovery of sensation was seen in all the patients at the end of this study.

CONCLUSION

The incidence of functional nerve disturbances is acceptable, since the progression towards recovery is inevitable. Prolonged neurosensory disturbance is greatly related to the degree of manipulation of the inferior alveolar nerve.