Cellulose Triacetate (CTA) Hollow-Fiber (HF) Membranes for Sustainable Seawater Desalination: A Review.

Cellulose triacetate (CTA)-based hollow fiber (HF) membrane is one of the commercially successful semipermeable membranes that has had a long progress since the time the excellent semi-permeable feature of cellulose-based polymers was found in 1957. Because of the reliable and excellent performances, especially for drinking water production from seawater, CTA-HFs have been widely used as reverse osmosis (RO) membranes, especially in arid regions. In this review, recent developments and research trends on CTA-HF membranes for seawater reverse osmosis (SWRO) plants were presented. A flux analytical model, an optimization strategy for chlorine injection without losing salt rejection performance, and a module of current high performance CTA RO membranes along with its plant operation data were updated in this paper. Furthermore, a newly developed CTA-HF membrane for brine concentration (BC) application (called BC membrane) was also addressed. Finally, RO/BC hybrid operation was introduced as an effective SWRO desalination technique that enables minimizing the volume of brine disposal from the RO plant by increasing the recovery ratio and the subsequent amount of produced freshwater, without an additional energy input.

Foreign-body granulomas and abscesses caused by dropped gallstones after cholecystectomy: Four cases diagnosed with multimodality imaging.

Four cases (age range, 60-78 years, male:female = 1:3) who had undergone cholecystectomy presented with fever (n = 1), right abdominal pain with fever (n = 1), appetite loss with fever (n = 1), and absence of symptoms (n = 1). Computed tomography (CT) showed an irregular-shaped invasive mass or fluid collection in the right Morrison's pouch, right paracolic gutter, gallbladder fossa, subphrenic space, or abdominal wall. CT and ultrasound revealed gallstones in the granuloma in 3 cases and an abscess in one case. The inflammatory process induced by dropped gallstones may mimic peritoneal malignancies. Awareness of cholecystectomy and the detection of gallstones in the lesion are essential for the diagnosis of dropped gallstones.

[A Case of Encapsulated Peritoneal Sclerosis Associated with a Ventriculo-Peritoneal Shunt].

We experienced a case of encapsulated peritoneal sclerosis(EPS)that developed as a result of peritoneal deterioration induced by ventriculo-peritoneal(VP)shunting. The patient was a 48-year-old man who underwent VP shunting five times since 1 month of age. Six months after the last operation, abdominal symptoms developed and the patient was hospitalized. A localized cyst was recognized in the left upper abdomen, and we diagnosed him with a cerebrospinal fluid pseudocyst. Soon, a shunt tube translocation was performed to another portion of the abdominal cavity, but a new short-term cyst appeared. During laparotomy, the inner surface of the abdominal cavity was very strong due to adhesions and the peritoneum was thickened. A large portion of the intestines and the mesentery was covered with a translucent film-like substance. Afterward, an ileus developed and he was diagnosed with EPS intraoperatively. We judged that an additional VP shunt was impossible, so a ventriculo-atrial shunt was placed. Afterward, his symptoms disappeared and the EPS improved. Although a few similar reports exist, this condition is thought to be extremely rare. Clinicians should recognize EPS as a complication of VP shunting.

Chain contraction and nonlinear stress damping in primitive chain network simulations.

Doi and Edwards (DE) proposed that the relaxation of entangled linear polymers under large deformation occurs in two steps: the fast chain contraction (via the longitudinal Rouse mode of the chain backbone) and the slow orientational relaxation (due to reptation). The DE model assumes these relaxation processes to be independent and decoupled. However, this decoupling is invalid for a generalized convective constraint release (CCR) mechanism that releases the entanglement on every occasion of the contraction of surrounding chains. Indeed, the decoupling does not occur in the sliplink models where the entanglement is represented by the binary interaction (hooking) of chains. Thus, we conducted primitive chain network simulations based on a multichain sliplink model to investigate the chain contraction under step shear. The simulation quantitatively reproduced experimental features of the nonlinear relaxation modulus G(t,γ). Namely, G(t,γ) was cast in the time-strain separable form, G(t,γ)=h(γ)G(t) with h(γ)=damping function and G(t)=linear modulus, but this rigorous separability was valid only at times t comparable to the terminal relaxation time, although a deviation from this form was rather small (within ±10%) at t>τ(R) (longest Rouse relaxation time). A molecular origin of this delicate failure of time-strain separability at t∼τ(R) was examined for the chain contour length, subchain length, and subchain stretch. These quantities were found to relax in three steps, the fast, intermediate, and terminal steps, governed by the local force balance between the subchains, the longitudinal Rouse relaxation, and the reptation, respectively. The contributions of the terminal reptative mode to the chain length relaxation as well as the subchain length/stretch relaxation, not considered in the original DE model, emerged because the sliplinks (entanglement) were removed via the generalized CCR mechanism explained above and the reformation of the sliplinks was slow at around the chain center compared to the more rapidly fluctuating chain end. The number of monomers in the subchain were kept larger at the chain center than at the chain end because of the slow entanglement reformation at the center, thereby reducing the tension of the stretched subchain at the chain center compared to the DE prediction. This reduction of the tension at the chain center prevented completion of the length equilibration of subchains at t∼τ(R) (which contradicts to the DE prediction), and it forces the equilibration to complete through the reptative mode at t≫τ(R). The delicate failure of time-strain separability seen for G(t,γ) at t∼τ(R) reflects this retarded length equilibration.

Primitive chain network simulations for entangled DNA solutions.

Molecular theories for polymer rheology are based on conformational dynamics of the polymeric chain. Hence, measurements directly related to molecular conformations appear more appealing than indirect ones obtained from rheology. In this study, primitive chain network simulations are compared to experimental data of entangled DNA solutions [Teixeira et al., Macromolecules 40, 2461 (2007)]. In addition to rheological comparisons of both linear and nonlinear viscoelasticities, a molecular extension measure obtained by Teixeira et al. through fluorescent microscopy is compared to simulations, in terms of both averages and distributions. The influence of flow on conformational distributions has never been simulated for the case of entangled polymers, and how DNA molecular individualism extends to the entangled regime is not known. The linear viscoelastic response and the viscosity growth curve in the nonlinear regime are found in good agreement with data for various DNA concentrations. Conversely, the molecular extension measure shows significant departures, even under equilibrium conditions. The reason for such discrepancies remains unknown.

Comparison between tissue harmonic imaging and liver-specific late-phase contrast-enhanced pulse-inversion imaging in the detection of hepatocellular carcinoma and liver metastasis.

PURPOSE: To assess whether liver-specific late-phase contrast-enhanced pulse-inversion (CE-PI) ultrasound imaging improves the detection of hepatocellular carcinoma (HCC) and liver metastasis in comparison with non-enhanced tissue harmonic imaging (THI). SUBJECTS AND METHODS: Twenty-one patients with HCC or liver metastasis were studied using standardized ultrasound harmonic settings. Sweeps through the hepatic lobes were done by THI, followed by late-phase CE-PI after Levovist injection. The number and segmental location of nodules detected by each method were recorded and compared with dynamic helical computed tomography (CT) as a reference. RESULTS: Sensitivity for the presence of the disease, metastasis or HCC, on a patient basis for each method was 81.0% for THI and 90.5% for CE-PI. Among the 78 metastatic nodules on reference CT, 31 true-positive, three false-positive, and 47 false-negative nodules were found by THI, while CE-PI depicted 54 true-positive, 12 false-positive and 24 false-negative lesions. Sensitivity in the detection of individual lesion was 51.8% for THI and 76.8% for CE-PI (p=0.0273). A total of 58 HCC nodules were detected on CT; 36 true-positive, 15 false-positive, and 22 false-negative lesions were found by THI; while CE-PI depicted 43 true-positive, six false-positive, and 15 false-negative lesions. Sensitivity in the detection of individual HCC was 42.9% by THI and 57.2% by CE-PI (p=0.2249 NS). CONCLUSION: In patients with liver metastasis, CE-PI statistically improved the sensitivity of lesion detection compared with THI. Conversely, CE-PI did not improve the sensitivity of lesion detection in patients with HCC.

Role of combined CT hepatic angiography and CT during arterial portography in the management of patients with hepatocellular carcinomas and liver metastases.

The purpose of this study was to evaluate the role of combined CT hepatic angiography (CTHA) and CT during arterial portography (CTAP) in the diagnosis and management of patients with hepatocellular carcinomas (HCC) and liver metastases. Fifty patients with HCC and 19 patients with liver metastases were referred for CTHA and CTAP prior to surgery or interventional therapy. Diagnosis was established by either surgery or clinical observation. Alterations of diagnosis and management resulting from CTHA and CTAP information were recorded. In patients with HCC, diagnosis was altered either by number, location or extent of lesions in 46% of patients and was 78% correct. Alterations of management were performed in 32% of the patients in total, and were correct in all but one. In patients with liver metastases, diagnosis was altered regarding either number, location or extent of lesions in 21% of patients and were 50% correct. Management was not altered after CTHA and CTAP in the patients with liver metastases. We conclude that CTHA and CTAP provide valuable clinical information for patients with HCC and significantly corrected their previous diagnosis and plans of management. CTHA and CTAP should be performed in patients with HCC when either surgical or interventional therapy is the treatment option.