Fabrication and Evaluation of Ultrasound-Responsive Emulsion Loading Paclitaxel for Targeted Chemotherapy.

Chemotherapy is the most widely used cancer treatment, but it has several drawbacks such as adverse side effects and low bioavailability. To address these limitations, various drug delivery systems have been investigated, including liposomes, micelles, and emulsions. These drug delivery technologies have been improving the efficacy and safety of conventional chemotherapy. This study presents an emerging drug delivery technology for targeted chemotherapy using drug-loaded ultrasound-responsive emulsion (URE) as a drug carrier and ultrasound technology for external activation. URE was designed to be responsive to ultrasound energy and fabricated by using an emulsification technique. To investigate this technology, paclitaxel, as a model drug, was used and encapsulated into URE. The size distribution, morphology, and drug release behavior of paclitaxel-loaded URE (PTX-URE) were characterized, and the echogenicity of PTX-URE was assessed by using ultrasound imaging equipment. The cellular uptake and cytotoxicity of PTX-URE with ultrasound were evaluated in breast cancer cells (MDA-MB-231). Our in vitro results indicate that the combination of PTX-URE and ultrasound significantly enhanced cellular uptake by 10.6-fold and improved cytotoxicity by 24.1% compared to PTX alone. These findings suggest that the URE platform combined with ultrasound is a promising technology to improve the drug delivery efficiency for chemotherapy.

Comment on the review paper "agricultural waste materials for adsorptive removal of phenol, chromium(VI) and cadmium(II) from wastewaters: A review" by Othmani et al. (2022).

Review papers help researchers understand the direction and flow of research and help beginners quickly acquire relevant knowledge. Therefore, the review paper should describe only accurate contents and should be written with only core and important matters. Recently, Othmani et al. (2022) reviewed more than 200 papers related to the adsorptive removal of three harmful pollutants: toxic organics (phenols), anionic heavy metal (Cr(VI)) and cationic heavy metal (Cd(II)) by agricultural waste materials. However, Cr(VI)-related section of this review is missing something important that should be provided to the readers of this journal. In fact, the removal mechanism of Cr(VI) by nonliving biomass including agricultural waste materials under acidic conditions is not a simple anion adsorption but a complex mechanism involving redox reaction called "adsorption-coupled reduction". Therefore, when interpreting the factors affecting Cr(VI) removal, it should be interpreted in terms of the redox reaction concept, not anion adsorption.

Sonophoresis with ultrasound-responsive liquid-core nuclei for transdermal drug delivery.

BACKGROUND: Sonophoresis can increase the delivery efficiency of various drugs into the skin. A recent advance in sonophoresis is the use of ultrasound-responsive liquid-core nuclei (URLN) to increase the probability of cavitation. In this study, we developed a URLN and ultrasound device, and demonstrated its effectiveness through in vitro and clinical tests. MATERIALS AND METHODS: Three types of experiments were designed to evaluate the efficiency of sonophoresis with URLN. First, a Franz diffusion cell with cosmetic ingredients was used to analyze quantitatively the amount of drug delivered to the porcine skin. Second, after the application of sonophoresis with URLN, the porcine skin surface was examined using scanning electron microscopy (SEM) to see the changes in morphology. Finally, a clinical test was performed to verify the utility of sonophoresis with URLN. RESULTS: The results indicate that sonophoresis with URLN can increase the amount of compound delivered by approximately 11.9-fold over 6 h for niacinamide and by 7.33-fold over 6 h for adenosine. In addition, we observed approximately 20-30 µm sized pores on porcine skin in SEM images. In clinical testing, the application of sonophoresis with cosmetics containing URLN for 3 min improved the efficiency of transdermal drug delivery by 1.9-fold, the depth of absorption by 2.0-fold, and the speed of absorption by 2.0-fold at 30 min after application. CONCLUSION: We expect that sonophoresis with specialized URLN in transdermal drug delivery could be used widely for various skin-related applications.

A study of solubilization of sewage sludge by hydrothermal treatment.

The use of activated sludge process for biological treatment of domestic and industrial wastewaters generates large amounts of sewage sludge, which is regarded as problematic biowaste. Conventional waste treatment methods such as landfilling and ocean pumping have been used to dispose the unwanted sludge, but this practice is no longer recommended due to serious secondary pollution and strict environmental regulations. Hydrothermal treatment represents a promising alternative that has attracted attention in recent years. In this study, batch experiments of hydrothermal treatment of domestic sewage sludge were conducted under varying conditions (temperature of 150-300 °C, reaction time of 0.5-3.0 h, and sludge concentration of 5-30 g/L). A statistical study of the responses, including disintegration degree and concentration of dissolved compounds, was performed using a response surface methodology. Optimal conditions for hydrothermal treatment of sewage sludge were obtained through mathematical modeling.

Evaluation of Doxorubicin-loaded Echogenic Macroemulsion for Targeted Drug Delivery.

BACKGROUND: The latest technology trend in targeted drug delivery highlights stimuliresponsive particles that can release an anticancer drug in a solid tumor by responding to external stimuli. OBJECTIVE: This study aims to design, fabricate, and evaluate an ultrasound-responsive drug delivery vehicle for an ultrasound-mediated drug delivery system. METHODS: The drug-containing echogenic macroemulsion (eME) was fabricated by an emulsification method using the three phases (aqueous lipid solution as a shell, doxorubicin (DOX) contained oil, and perfluorohexane (PFH) as an ultrasound-responsive agent). The morphological structure of eMEs was investigated using fluorescence microscopy, and the size distribution was analyzed by using DLS. The echogenicity of eME was measured using a contrast-enhanced ultrasound device. The cytotoxicity was evaluated using a breast cancer cell (MDA-MB-231) via an in vitro cell experiment. RESULTS: The obtained eME showed an ideal morphological structure that contained both DOX and PFH in a single particle and indicated a suitable size for enhancing ultrasound response and avoiding complications in the blood vessel. The echogenicity of eME was demonstrated via an in vitro experiment, with results showcasing the potential for targeted drug delivery. Compared to free DOX, enhanced cytotoxicity and improved drug delivery efficiency in a cancer cell were proven by using DOX-loaded eMEs and ultrasound. CONCLUSION: This study established a platform technology to fabricate the ultrasound-responsive vehicle. The designed drug-loaded eME could be a promising platform with ultrasound technology for targeted drug delivery.

Comparison of quantification of intraretinal hard exudates between optical coherence tomography en face image versus fundus photography.

PURPOSE: To compare the quantification of intraretinal hard exudate (HE) using en face optical coherence tomography (OCT) and fundus photography. METHODS: Consecutive en face images and corresponding fundus photographs from 13 eyes of 10 patients with macular edema associated with diabetic retinopathy or Coats' disease were analyzed using the machine-learning-based image analysis tool, "ilastik." RESULTS: The overall measured HE area was greater with en face images than with fundus photos (en face: 0.49 ± 0.35 mm2 vs. fundus photo: 0.34 ± 0.34 mm2, P < 0.001). However, there was an excellent correlation between the two measurements (intraclass correlation coefficient [ICC] = 0.844). There was a negative correlation between HE area and central macular thickness (CMT) (r = -0.292, P = 0.001). However, HE area showed a positive correlation with CMT in the previous several months, especially in eyes treated with anti-vascular endothelial growth factor (VEGF) therapy (CMT 3 months before: r = 0.349, P = 0.001; CMT 4 months before: r = 0.287, P = 0.012). CONCLUSION: Intraretinal HE can be reliably quantified from either en face OCT images or fundus photography with the aid of an interactive machine learning-based image analysis tool. HE area changes lagged several months behind CMT changes, especially in eyes treated with anti-VEGF injections.

Synthesis of laboratory Ultrasound Contrast Agents.

Ultrasound Contrast Agents (UCAs) were developed to maximize reflection contrast so that organs can be seen clearly in ultrasound imaging. UCAs increase the signal to noise ratio (SNR) by linear and non-linear mechanisms and thus help more accurately visualize the internal organs and blood vessels. However, the UCAs on the market are not only expensive, but are also not optimized for use in various therapeutic research applications such as ultrasound-aided drug delivery. The UCAs fabricated in this study utilize conventional lipid and albumin for shell formation and perfluorobutane as the internal gas. The shape and density of the UCA bubbles were verified by optical microscopy and Cryo SEM, and compared to those of the commercially available UCAs, Definity® and Sonovue®. The size distribution and characteristics of the reflected signal were also analyzed using a particle size analyzer and ultrasound imaging equipment. Our experiments indicate that UCAs composed of spherical microbubbles, the majority of which were smaller than 1 um, were successfully synthesized. Microbubbles 10 um or larger were also identified when different shell characteristics and filters were used. These laboratory UCAs can be used for research in both diagnoses and therapies.

Ecotoxicity study of reduced-Cr(III) generated by Cr(VI) biosorption.

Hexavalent chromium (Cr(VI)) is a known carcinogen in living organisms, and many studies have investigated Cr(VI) removal methods. Biosorption, one of the Cr(VI) removal methods, is dominated by chemical binding, ion exchange, physisorption, chelation and oxidation-reduction. Among these mechanisms, Cr(VI) can be removed by nonliving biomass through a redox reaction, which has been recognized as 'adsorption-coupled reduction'. Cr(VI) is reduced to Cr(III) during biosorption, but there are no studies on the property and toxicity of the reduced-Cr(III). In this study, the harmfulness of reduced-Cr(III) was identified through assessment of mobility and toxicity in nature. Pine bark, a low-cost biomass, was used to remove Cr(VI) from aqueous solution. Reduced-Cr(III) was characterized by structural features using X-ray Absorption Near Edge Structure (XANES) spectra, mobility assessed using precipitation, adsorption and soil column test, and toxicity using radish sprouts and water flea. XANES analysis confirmed that reduced-Cr(III) has an unsymmetrical structure, and the reduced-Cr(III) showed low mobility and was virtually non-toxic, and helpful for plant growth. Our findings demonstrate that Cr(VI) biosorption technology using pine bark is a groundbreaking technology for Cr(VI) detoxification.

Comparison of retinal nerve fiber layer thickness and Bruch's membrane opening minimum rim width thinning rate in open-angle glaucoma.

This study aimed to compare the rate of thinning between retinal nerve fiber layer thickness (RNFLT) and Bruch's membrane opening minimum rim width (BMO-MRW) in open-angle glaucoma (OAG) according to glaucoma severity. We retrospectively reviewed subjects with a total of 111 eyes with OAG that had undergone optical coherence tomography more than four times during more than 3 years of follow-up. The subjects were divided into three groups based on the mean deviation (MD) of the baseline visual field test: high MD (MD > - 2 dB), medium MD (- 2 dB ≥ MD > - 6 dB), and low MD (- 6 dB ≥ MD > - 12 dB) groups. A linear mixed model was employed to compare the rate of thinning between RNFLT and BMO-MRW among the three groups. The rate of RNFLT thinning was fastest in the inferotemporal sector in all three groups. The rate of BMO-MRW thinning was fastest in the inferotemporal sector of the high MD group and the superotemporal sector of the other two groups. Among the three groups, the rate of RNFLT thinning was not significantly different in the global sector and all sectors except the nasal sector. The rate of BMO-MRW thinning in the inferotemporal sector showed no significant difference, but that in the superotemporal sector was faster in the medium MD and low MD groups than in the high MD group. The fastest rate of RNFLT thinning was consistently observed in the inferotemporal sector, but BMO-MRW showed a change in the fastest thinning sector from inferotemporal to superotemporal, with increasing severity in early to moderate OAG. The difference in the changes in the two parameters may help understand the pathogenesis of glaucoma and predict its progression.

Energy-Efficient III-V Tunnel FET-Based Synaptic Device with Enhanced Charge Trapping Ability Utilizing Both Hot Hole and Hot Electron Injections for Analog Neuromorphic Computing.

A charge trap device based on field-effect transistors (FET) is a promising candidate for artificial synapses because of its high reliability and mature fabrication technology. However, conventional MOSFET-based charge trap synapses require a strong stimulus for synaptic update because of their inefficient hot-carrier injection into the charge trapping layer, consequently causing a slow speed operation and large power consumption. Here, we propose a highly efficient charge trap synapse using III-V materials-based tunnel field-effect transistor (TFET). Our synaptic TFETs present superior subthreshold swing and improved charge trapping ability utilizing both carriers as charge trapping sources: hot holes created by impact ionization in the narrow bandgap InGaAs after being provided from the p+-source, and band-to-band tunneling hot electrons (BBHEs) generated at the abrupt p+n junctions in the TFETs. Thanks to these advances, our devices achieved outstanding efficiency in synaptic characteristics with a 5750 times faster synaptic update speed and 51 times lower sub-fJ/um2 energy consumption per single synaptic update in comparison to the MOSFET-based synapse. An artificial neural network (ANN) simulation also confirmed a high recognition accuracy of handwritten digits up to ∼90% in a multilayer perceptron neural network based on our synaptic devices.

Enhanced Luminance of CdSe/ZnS Quantum Dots Light-Emitting Diodes Using ZnO-Oleic Acid/ZnO Quantum Dots Double Electron Transport Layer.

The widely used ZnO quantum dots (QDs) as an electron transport layer (ETL) in quantum dot light-emitting diodes (QLEDs) have one drawback. That the balancing of electrons and holes has not been effectively exploited due to the low hole blocking potential difference between the valence band (VB) (6.38 eV) of ZnO ETL and (6.3 eV) of CdSe/ZnS QDs. In this study, ZnO QDs chemically reacted with capping ligands of oleic acid (OA) to decrease the work function of 3.15 eV for ZnO QDs to 2.72~3.08 eV for the ZnO-OA QDs due to the charge transfer from ZnO to OA ligands and improve the efficiency for hole blocking as the VB was increased up to 7.22~7.23 eV. Compared to the QLEDs with a single ZnO QDs ETL, the ZnO-OA/ZnO QDs double ETLs optimize the energy level alignment between ZnO QDs and CdSe/ZnS QDs but also make the surface roughness of ZnO QDs smoother. The optimized glass/ITO/PEDOT:PSS/PVK//CdSe/ZnS//ZnO-OA/ZnO/Ag QLEDs enhances the maximum luminance by 5~9% and current efficiency by 16~35% over the QLEDs with a single ZnO QDs ETL, which can be explained in terms of trap-charge limited current (TCLC) and the Fowler-Nordheim (F-N) tunneling conduction mechanism.

Optimization and comparison of methane production and residual characteristics in mesophilic anaerobic digestion of sewage sludge by hydrothermal treatment.

Anaerobic digestion is the preferred method for treating sewage sludge because of its ability to reduce sludge volume and produce biogas. However, conventional anaerobic digestion has a long retention time and low degradation rate. In recent years, hydrothermal treatment has been used to improve the hydrolysis of sewage sludge and biogas production. This process tends to focus on maximizing biogas production. However, very little research has been done on anaerobic digestion residues. In this study, batch experiments were conducted to investigate the effect of hydrothermal temperature on methane production and the contents of liquid fraction after anaerobic digestion (centrate). Experimental conditions were designed using a response surface method and central composite model. A quadratic equation was used to interpret the individual and interactive effects of hydrothermal conditions on anaerobic digestion. Given the maximum biogas production and the minimum concentrate concentration, the optimal operating condition was determined by a 186 °C hydrothermal temperature and a reaction time of 106 min. Under these conditions, the following results could be obtained: methane production (200.5 ± 7.7 mL-CH4/gVSadded), TCOD (16,572 ± 348 mg/L), sCOD (1240 ± 65 mg/L), sTN (658.9 ± 8.0 mg/L) and ammonia (525 ± 27 mg/L).

A physical method to enhance transdermal delivery of a tissue optical clearing agent: combination of microneedling and sonophoresis.

BACKGROUND AND OBJECTIVES: Various physical methods, such as microneedling, laser ablation, sonophoresis, and sandpaper, have been widely studied to enhance the transdermal delivery of tissue optical clearing (TOC) agents. A previous study demonstrated that the microneedling method could effectively enhance the permeability of a TOC agent through the skin barrier. STUDY DESIGN/MATERIALS AND METHODS: In this study, we introduce a new physical combination method which utilizes both microneedling and sonophoresis to further enhance the transdermal delivery of a TOC agent, glycerol. Porcine skin samples were divided into a control group treated only with the microneedle roller and a test group treated with both the microneedle roller and sonophoresis. Glycerol was applied topically after microneedling. The optimal concentration and transdermal delivery efficacy of glycerol were quantitatively evaluated. RESULTS: A 70% glycerol solution was determined to be the optimal concentration for the combination method. The combination method resulted in approximately a 2.3-fold higher transdermal diffusion rate of glycerol when compared to the microneedling method alone. CONCLUSION: The combination method and optimal glycerol concentration effectively enhanced transdermal delivery of glycerol by accelerating the diffusion rate through the skin barrier.

Patellofemoral contact mechanics after transposition of tibial tuberosity in dogs.

BACKGROUND: Tibial tuberosity transposition (TTT) causes caudalization of the patellar ligament insertion in canine medial patellar luxation, which can lead to increases in patellofemoral contact pressure. OBJECTIVES: The purpose of this study is to confirm the effect of patellofemoral contact mechanics after craniolateral and caudolateral transposition of tibial tuberosity in normal canine hindlimbs. METHODS: Craniolateral and caudolateral transposition of tibial tuberosity was performed in 5 specimens, respectively. The pressure was measured in the specimen before TTT, and then in the same specimen after TTT. In this process, data was obtained in 10 specimens. The measurement results were output as visualization data through the manufacturer's software and numerical data through spreadsheet. Based on these 2 data and the anatomical structure of the patellofemoral joint (PFJ) surface, whole measurement area was analysed by dividing into medial, lateral and central area. RESULTS: In craniolateralization of tibial tuberosity, total, medial, central contact pressure was decreased and lateral contact pressure was not statistically changed lateral contact pressure than normal PFJ. In caudolateralization of tibial tuberosity, total, lateral contact pressure was increased and medial contact pressure was not statistically changed than normal PFJ. Although not statistically significant changed, central contact pressure in caudolateralization of tibial tuberosity was increased in all 5 specimens. CONCLUSIONS: These results imply that traditional TTT, prone to caudal shift of patellar tendon, can increase retropatellar pressure may lead to various complications and diseases of the stifle joint.

New insight into continuous recirculation-process for treating arsenate using bacterial biosorbent.

In this study, a new recirculation column reactor system for arsenate removal using a polyethylenimine coated bacterial biosorbent was developed. Solution pH was the most important factor in process design and operation. In order to control and optimize solution pH favorable for arsenate removal, a pH control and recirculation system was added to a column reactor. The effects of recycle ratio, initial arsenate concentration, and flow rate on the arsenate removal performance of the developed process were examined. Thomas and Yoon-Nelson models were used to interpret the breakthrough curve of arsenate removal. The maximum arsenate adsorption amount of the new reactor was determined to be 50.86 mg/g by the Thomas model. Importantly, the new reactor showed unimpeded adsorption performance compared with that in the batch experiments. The desorption study also showed excellent reusability. The results indicated that the newly developed process could be a promising application prospect for removing arsenate.

Current Status of Amebic Liver Abscess in Korea Comparing with Pyogenic Liver Abscess.

Backgrounds/Aims: With the improvement of hygiene, the incidence of amebic liver abscess is decreasing in South Korea. On the other hand, there is little data on the status of amebic liver abscess compared to pyogenic liver abscess. Methods: Patients with an amebic liver abscess, in whom Entamoeba histolytica (E. histolytica) IgG was positive, were identified retrospectively in a university hospital. The clinical, laboratory, and radiological characteristics of amebic liver abscess were compared with those of pyogenic liver abscess in the same period. Results: Between March 2010 and October 2016, 413 patients with a liver abscess were identified. Among them, the serologic test for E. histolytica was performed in 209 patients. Fifteen (7.2%) were classified as an amebic liver abscess, and the remainder were diagnosed with a pyogenic liver abscess. The age, gender, white blood cell, and CRP was comparable between the two groups. Procalcitonin was lower in amebic liver abscess than the pyogenic one. On CT, peripheral rim enhancement was more frequent, but cluster signs were not observed in amebic liver abscess compared to pyogenic liver abscess. None of the patients with amebic liver abscess died. In contrast, the mortality of pyogenic liver abscess was 4.7%. Conclusions: Amebic liver abscess should still be considered as one of the causes of liver abscess in Korea. It is difficult to discriminate an amebic liver abscess from a pyogenic liver abscess only according to the clinical, laboratory, and radiologic findings. Therefore, it is necessary to perform a serologic test for E. histolytica for a precise evaluation of liver abscess in a high-risk group.

Development of 64Cu-loaded Perfluoropentane Nanodroplet: A Potential Tumor Theragnostic Nano-carrier and Dual-Modality PET-Ultrasound Imaging Agents.

The purpose of this study was to develop and preliminarily evaluate phospholipid-shelled nanodroplets (NDs) encapsulating perfluoropentane (PFP) and radioactive 64Cu as a hybrid positron emission tomography (PET)-ultrasound (US) probe. PFP NDs were fabricated by mixing liquid-phase PFP with a phospholipid solution. The 64Cu was encapsulated into the NDs in a size-controlled manner by exploiting the hydrophobicity of 64Cu-diacetyl-bis(N4-methylthiosemicarbazone) (64Cu-ATSM) using a vial mixer and an extruder. The fabricated 64Cu-loaded PFP NDs (64Cu-PFP NDs) were evaluated using in vitro/in vivo PET-computed tomography (PET-CT), US imaging and transmission electron microscopy. In the in vitro PET images, the 64Cu-PFP NDs were observed as a hot spot in the lower section of the test tube. In the acquired US images, the mean region of interest brightness values of 64Cu-PFP NDs were revealed by their strong echo image. In a tumor-bearing mouse animal model, tumor uptake of the 64Cu-PFP NDs was low, that is, approximately 65%, compared with that of only free 64Cu, as determined by PET-delayed imaging analysis. The dual-function concept of the NDs is expected to contribute to the prognosis and effectiveness of therapy by fusing the science and technology of nuclear medicine and US.

Electroluminescence of a single active layer polymer-nanocrystal hybrid light-emitting diode with inversion symmetry.

A hybrid polymer-nanocrystal (NC) light-emitting diode (LED) device with a single active layer structure is simply fabricated by a spin coating. From a high-resolution transmission electron microscopy (HRTEM) study, each PVK polymer particle is observed to be capped with TPBi molecules and CdSe/ZnS NCs are mainly distributed along the circumference of PVK and TPBi surfaces, resulting in a core-shell polymer-NC hybrid of [CdSe/ZnS]/TPBi/[CdSe/ZnS]/PVK. An Al/[CdSe/ZnS]/TPBi/[CdSe/ZnS]/PVK/indium-tin oxide(ITO)/glass LED shows electroluminescence (EL) centered at around 585 nm at the forward bias of +10 V, which clearly reveals that CdSe/ZnS NCs existing at the interface between PVK and TPBi act as recombination centers for excitons. In particular, EL can be observed at both forward bias and reverse bias, and this means that this device with an isotropic distribution of NCs has an inversion symmetry.

Carrier transport in flexible organic bistable devices of ZnO nanoparticles embedded in an insulating poly(methyl methacrylate) polymer layer.

The bistable effects of ZnO nanoparticles embedded in an insulating poly(methyl methacrylate) (PMMA) polymer single layer by using flexible polyethylene terephthalate (PET) substrates were investigated. Transmission electron microscopy (TEM) images revealed that ZnO nanoparticles were formed inside the PMMA polymer layer. Current-voltage (I-V) measurement on the Al/ZnO nanoparticles embedded in an insulating PMMA polymer layer/ITO/PET structures at 300 K showed a nonvolatile electrical bistability behavior with a flat-band voltage shift due to the existence of the ZnO nanoparticles, indicative of trapping, storing, and emission of charges in the electronic states of the ZnO nanoparticles. The carrier transport mechanism of the bistable behavior for the fabricated organic bistable device (OBD) structures is described on the basis of the I-V results by analyzing the effect of space charge.

Effects of long-term pH elevation on the sulfate-reducing and methanogenic activities of anaerobic sewer biofilms.

The dosage of alkali is often applied by the wastewater industry to reduce the transfer of hydrogen sulfide from wastewater to the sewer atmosphere. In this paper the activities of Sulfate Reducing Bacteria (SRB) and Methanogenic Archaea (MA) under elevated pH conditions (8.6 and 9.0) were evaluated in a laboratory scale anaerobic sewer reactor. Compared to those in a control reactor without pH control (pH 7.6+/-0.1), the SRB activity was reduced by 30% and 50%, respectively, at pH 8.6 and pH 9.0. When normal pH was resumed, it took approximately 1 month for the SRB activity to fully recover. Methanogenic activities developed in the control reactor in 3 months after the reactor start-up, while no significant methanogenic activities were detected in the experimental reactor until normal pH was resumed. The results suggest that elevated pH at 8.6-9.0 suppressed the growth of methanogens. These experimental results clearly showed that, in addition to its well-known effect of reducing H(2)S transfer from the liquid to the gas phase, pH elevation considerably reduces sulfide and methane production by anaerobic sewer biofilms. These findings are significant for the optimal use of alkali addition to sewers for the control of H(2)S and CH(4) emissions. A model-based study showed that, by adding the alkali at the beginning rather than towards the end of a rising main, substantial savings in chemicals can be achieved while achieving the same level of sulfide emission control, and complete methane emission control.