A Hybrid Convolutional and Recurrent Neural Network for Multi-Sensor Pile Damage Detection with Time Series.

Machine learning (ML) algorithms are increasingly applied to structure health monitoring (SHM) problems. However, their application to pile damage detection (PDD) is hindered by the complexity of the problem. A novel multi-sensor pile damage detection (MSPDD) method is proposed in this paper to extend the application of ML algorithms in the automatic identification of PDD. The time-series signals collected by multiple sensors during the pile integrity test are first processed by the traveling wave decomposition (TWD) theory and are then input into a hybrid one-dimensional (1D) convolutional and recurrent neural network. The hybrid neural network can achieve the automatic multi-task identification of pile damage detection based on the time series of MSPDD results. Finally, the analytical solution-based sample set is utilized to evaluate the performance of the proposed hybrid model. The outputs of the multi-task learning framework can provide a detailed description of the actual pile quality and provide strong support for the classification of pile quality as well.

Pile Damage Detection Using Machine Learning with the Multipoint Traveling Wave Decomposition Method.

The in-hole multipoint traveling wave decomposition (MPTWD) method is developed for detecting and characterizing the damage of cast in situ reinforced concrete (RC) piles. Compared with the results of MPTWD, the results of the in-hole MPTWD reconstruction technique are found ideal for evaluating the lower-part pile integrity and are further utilized to establish a data-driven machine-learning framework to detect and quantify the degree of damage. Considering the relatively small number of field test samples of the in-hole MPTWD method at this stage, an analytical solution is employed to generate sufficient samples to verify the feasibility and optimize the performance of the machine learning modeling framework. Two types of features extracted by the distributed sampling and statistical and signal processing techniques are applied to three machine-learning classifiers, i.e., logistic regression (LR), extreme gradient boosting (XGBoost) and multilayer perceptron (MLP). The performance of the data-driven machine-learning framework is then evaluated through a specific case study. The results demonstrate that all three classifiers perform better when employing the statistical and signal processing techniques, and the total of 24 extracted features are sufficient for the machine-learning algorithms.

Torsional Low-Strain Test for Nondestructive Integrity Examination of Existing High-Pile Foundation.

Low-strain tests are widely utilized as a nondestructive approach to assess the integrity of newly piled foundations. So far, the examination of existing pile foundations is becoming an indispensable protocol for pile recycling or post-disaster safety assessment. However, the present low-strain test is not capable of testing existing pile foundations. In this paper, the torsional low-strain test (TLST) is proposed to overcome this drawback. Both the upward and downward waves are considered in the TLST wave propagation model established in this paper so that a firm theoretical basis is grounded for the test signal interpretations. A concise semi-analytical solution is derived and its rationality is verified by comparisons with the existing solutions for newly piled foundations and the finite element results. The main conclusions of this study can be drawn as follows: (1). by placing the sensors where the incident wave is applied, the number of reflected signals can be minimized; (2). the defects can be more evidently identified if the incident wave/sensors are input/installed close to the superstructure/pile head.

Electrokinesis is a microbial behavior that requires extracellular electron transport.

We report a previously undescribed bacterial behavior termed electrokinesis. This behavior was initially observed as a dramatic increase in cell swimming speed during reduction of solid MnO(2) particles by the dissimilatory metal-reducing bacterium Shewanella oneidensis MR-1. The same behavioral response was observed when cells were exposed to small positive applied potentials at the working electrode of a microelectrochemical cell and could be tuned by adjusting the potential on the working electrode. Electrokinesis was found to be different from both chemotaxis and galvanotaxis but was absent in mutants defective in electron transport to solid metal oxides. Using in situ video microscopy and cell tracking algorithms, we have quantified the response for different strains of Shewanella and shown that the response correlates with current-generating capacity in microbial fuel cells. The electrokinetic response was only exhibited by a subpopulation of cells closest to the MnO(2) particles or electrodes. In contrast, the addition of 1 mM 9,10-anthraquinone-2,6-disulfonic acid, a soluble electron shuttle, led to increases in motility in the entire population. Electrokinesis is defined as a behavioral response that requires functional extracellular electron transport and that is observed as an increase in cell swimming speeds and lengthened paths of motion that occur in the proximity of a redox active mineral surface or the working electrode of an electrochemical cell.

Could Concurrent Capecitabine with Hypofractionated Radiotherapy in Elderly Patients with Muscle-Invasive Bladder Cancer be an Option?

BACKGROUND: Repopulation of tumor cells during radiotherapy of transitional cell bladder carcinoma is believed to be a significant cause for treatment failure, and it was reported from clinical observations that the local control rate decreased with a prolonged treatment time, so accelerated hypofractionated radiotherapy with concurrent capecitabine may provide good local control in elderly patients unfit for surgery. The study aimed to evaluate the tolerability and efficacy of hypofractionated radiotherapy with capecitabine in elderly patients with urothelial carcinoma. METHODS: Between October 2019 and September 2021, 30 patients with muscle-invasive bladder cancer staged T2-4aN0M0, underwent transurethral resection of bladder tumor followed by capecitabine (825 mg/m2 orally, 2 times a day) and radiation therapy (55 Gy in 2.2 Gy per fraction). RESULTS: Thirty patients with a median age of 73.5 years (range, 65-85) were included in our study. Most patients had T2N0, and T3N0 (28 patients), furthermore 73.3% had an intermediate-grade tumor, Transurethral resection of bladder tumor was incomplete in 43.3. No grade 4 toxicity was documented. Grade 3 urinary toxicities occurred in two patients requiring hospitalization and temporal radiation cessation. Regarding late toxicities, no grade 3 or 4 toxicity was reported. A complete response was obtained in 56.7% of  patients. After a median follow-up of 16 months, the locoregional control rate was 63%. Overall survival, local failure-free survival, and event-free survival were 100%, 93.3%, 80% and 43.3%, 33.3%, 30% at one and two years respectively. CONCLUSION: Hypofractionated chemoradiation with capecitabine, appears to be an effective and well-tolerated curative treatment strategy in the selected elderly population with urothelial carcinoma.

Microstructure of gamma-ray developed polymeric nanocomposite respecting cesium and cobalt removal from aqueous solutions.

The nanoparticles of fly ash (FA) were obtained by high energy ball milling of their parent Class C kind for subsequent synthesis of poly(acrylamide-acrylic acid)/fly ash (poly(AM-AA)/FA) nanocomposite. The gamma-radiation induced polymerization was applied to achieve this concern. Different techniques were utilized to characterize such nanocomposite. The sorption abilities of the synthesized nanocomposite toward 60Co2+ and 134Cs + radionuclides were evaluated using batch and fixed-bed column approaches. Batches were designed at constants of solution pH (6.5-7.0 ± 0.02), nanocomposite particle size and dosage (106-250 µm and 0.1 L/g, respectively). The microstructure of such nanocomposite (<100 nm) was mainly amorphous with porous rough surfaces containing homogenous distribution of the incorporated nano-FA. About 56.46 and 47.9 mg/g of Co2+ and Cs+ were sorbed at equilibrium with an ion exchange reaction mechanism. Langmuir, Freundlich and Dubinin-Radushkevich D-R isotherm model parameters were calculated indicating the favorability of all sorption processes. The spontaneous and endothermic natures of sorption were observed by the calculated ΔG° and ΔH° thermodynamic parameters, respectively. Thomas, Yoon-Nelson and Adams Bohart models were fitted to the fixed-bed column data at varied conditions. The predicted sorption capacities of Thomas were very close to those obtained experimentally. Modeling of the fixed-bed column data dominates that the external mass transfer kinetics was predominant in the initial parts of the fixed-beds. Values required for retaining 50% of the initial sorbate concentration were extended from 89.05 to 68.55 to 177.2 and 149.3 min for 60Co2+ and 134Cs + radionuclides, respectively, by increasing bed depth from 1.5 to 3.0 cm. Modification of FA to its nano-scale form with the subsequent synthesis of a nanocomposite material having sorption capabilities made a duplicate beneficial environmental concern.

Electrochemical regeneration of hexavalent chromium from aqueous solutions in a gas sparged parallel plate reactor.

In this study anodic oxidation of Cr2(SO4)3 was carried out in an air-sparged divided parallel plate cell. Variables studied were current density, Cr2(SO4)3 concentration, and superficial air velocity. The rate constant of Cr2(SO4)3 oxidation was found to increase with increasing current density and Cr2(SO4)3 concentration. The effect of air sparging was found to depend on Cr2(SO4)3 concentrations, at high Cr2(SO4)3 concentration (> 0.1 M) air sparging does not affect the rate constant of the reaction denoting that the reaction is charge transfer controlled. As Cr2(SO4)3 concentration decreases below 0.1 M the reaction becomes under mixed diffusion and chemical control and the rate constant increases with increasing air superficial velocity, the lower Cr2(SO4)3 concentration the higher the contribution of diffusion to the reaction rate. The current efficiency of the process ranged from 20 to 85% depending on current density and Cr2(SO4)3 concentration. Electrical energy consumption which ranged from 1.8 to 14.4 kW h/kg of Cr6+ was found to increase with increasing current density and decreases with increasing Cr2(SO4)3 concentration. Air sparging was found to decrease electrical energy consumption in the case of dilute solutions << 0.1 M Cr2(SO4)3.

Purification of rad-waste arising from irradiated natural tin target towards tellurium-125m/antimony-125 radioisotope generator elaboration.

The present study introduces a new approach based on an irradiated tin target's impurity to produce a125Sb/125mTe radioisotope generator. A prepared generator gel matrix of zirconium-silico-tungstate was loaded with 6660 MBq (180 mCi) activity of the separated antimony. The loading and elution method has been studied as a function of the concentration of H2SO4 acid solution. The effect of mild oxidant (ascorbic acid) in the loading and complexing agent (acetic acid) in elution was investigated to improve the generator's elution profile. A mixture of (0.5 M) ascorbic acid and (0.5 M) H2SO4 acid solution as a loading solution resulted in a maximum distribution of 125Sb. In comparison, using (0.4 M) acetic acid as an eluent solution 125mTe yield reached 88.7% and minimised percentage of 125Sb breakthrough was obtained (<0.01%).

Batch kinetics of 134Cs and 152+154Eu radionuclides onto poly-condensed feldspar and perlite based sorbents.

Sorption of fission products onto polycondensed aluminosilicates (PC-AS(s)) is a relatively recent and gets out the mechanisms by which the formers are trapped. Here, PC feldspar (PC-FD), perlite (PC-PR) and their blend (PC-FDPR) were synthesized by the alkaline activation using Na-/K-silicates at Si-modulus of 1.35. XRD patterns revealed the semi-crystalline natures of sorbents. Na- and K-feldspars were detected in PC-FD while Na-based carbonate crystals were detected in others. Components of the poly(sialate-disiloxo) structure were detected in FT-IR spectra. Thermographs were deconvoluted and the amounts of the sticking and zeolitic water were estimated. Kinetic batches for sorption of 134Cs and 152+154Eu onto the elaborated yields were constructed. Ranking of sorbed amounts (qe) was varied from 134Cs (PC-FDPR>PC-FD>PC-PR) to 152+154Eu (PC-PR>PC-FD>PC-FDPR). Maximum qe was recorded at elevated temperature (323 K) to be 4.28 and 1.45 mg/g for 134Cs/PC-FDPR and 152+154Eu/PC-PR, respectively. Along all batches, chemi-sorption mechanism is common denominator. The effective diffusion coefficients (Di) were in the order of 10-14 m2/s. Both PC-FD and PC-FDPR recorded greater Di values of 134Cs than 152+154Eu. The low values of Ea (kJ/mol) reflected the weak adsorbats-adsorbents interactions. While, the high negative values of ∆S‡ suggested that the studied radionuclides were sorbed in associative reaction mechanism.

Simultaneous interferometric measurement of corrosive or demineralizing bacteria and their mineral interfaces.

Here, we report simultaneous surface profile measurements of several bacterial species involved in microbially influenced corrosion and their solid-surface interfaces by using vertical scanning interferometry. The capacity to nondestructively quantify microscale topographic changes beneath a single bacterium without its removal offers a unique opportunity to examine in vivo microbe-surface interactions.

Assessment of individual and mixed alkali activated binders for solidification of a nuclear grade organic resin loaded with 134Cs, 60Co and 152+154Eu radionuclides.

Individual metakaolin-based alkali activated binder (AAB) was utilized to optimize binary and ternary ones having feldspar/metakaolin and slag/feldspar+metakaolin ratios of 0.3 and 0.4, respectively. These three AABs had the ability to directly solidify 10.0 (FMK0-10R), 8.0 (FMK3-8R) and 12.0% (S4FMK3-12R) of the nuclear grade KY-2 beads, respectively, recording compressive strength values greater than twice the waste acceptance criteria. Leaching of 134Cs, 60Co and 152+154Eu, whether singularly or multiply loaded, was assessed. The multi-radionuclidic systems recorded greater leached fractions in the order of: 152+154Eu>134Cs>60Co. Among the studied systems, S4FMK3-12R formulations recorded the lowest diffusion coefficient values (D). Gamma-irradiation made a desired influence on all studied leaching systems with inverse relationships with the applied irradiation doses. Irradiating the optimized ternary AAB with 3.0 KGy (S4FMK3-12R-É£3) yielded the lowest D value (6.65 × 10-13 cm2/s), when single component-60Co was diffused. The leachability indexes of all irradiated AABs were not only greatly exceeded the value of 6 but also sometimes be twice such value. XRD, FT-IR and SEM examinations of S4FMK3, S4FMK3-12R and S4FMK3-12R-É£3 reflected their multi-layered semicrystalline natures and to what extent these AABs and the solidified beads had good and poor radiation stabilities, respectively, with a proposed three-step mechanism of such instability.

Synthesis of docosahexaenoic acid-loaded silver nanoparticles for improving endothelial dysfunctions in experimental diabetes.

OBJECTIVE: To investigate the ability of docosahexaenoic acid (DHA)-loaded silver nanoparticles (AgNPs) in facilitating the incorporation of DHA in the cell membrane, improve cell membrane structure, and attenuate endothelial dysfunction in experimental diabetes. METHODS: DHA/AgNPs were prepared using a nanoprecipitation technique. Fifty male albino rats were used in this study; 10 of them were served as the control group and 40, as the experimental groups, were injected with streptozotocin. Then, the experimental groups were subdivided into diabetic, diabetic treated with DHA, diabetic treated with AgNPs, and diabetic treated with DHA/AgNPs groups. RESULTS: DHA/AgNPs have small spherical size as proved from ultraviolet-visible spectroscopy, transmission electron microscope, dynamic light scattering, and scanning electron microscope techniques. Cell membrane cholesterol and triglycerides showed a significant elevation in the diabetic group compared to the control, but treatment with DHA and DHA/AgNPs caused a significant reduction in both. Treatment with AgNPs and DHA/AgNPs caused a significant improvement in asymmetric dimethylarginine and nitric oxide levels compared to the diabetic group. Cell membrane fatty acids showed that omega-6 polyunsaturated fatty acids (PUFAs) were significantly elevated, while omega-3 PUFA were significantly reduced in the diabetic group compared to the control. There is a significant improvement in the levels of fatty acids in all groups after treatment with DHA, silver, or DHA/AgNPs. CONCLUSION: DHA/AgNPs are potent agents for the improvement of diabetic complication and endothelial dysfunction in experimental diabetes.

Two-step method for preparation of NaA-X zeolite blend from fly ash for removal of cesium ions.

Pure zeolites can be synthesized from silica extracts obtained from fly ash by alkaline leaching. The extraction potential of industrial by-product fly ash was investigated under repeated fusion process conditions. The amount of extracted silica was 131.43 g/kg ash while the amount extracted alumina was limited to 41.72 g/kg ash. The results of zeolite synthesis from the Si-bearing extracts demonstrated that pure zeolites with high cation exchange capacity (4.624 meq/g) can be produced. The sorption potential of synthesized A-X zeolite blend for the removal of cesium ions has been investigated. The influences of pH, contact time and temperature have been reported. Thermodynamic parameters such as changes in Gibbs free energy (DeltaG degrees), enthalpy (DeltaH degrees) and entropy (DeltaS degrees) were calculated. A comparison of kinetic models applied to the sorption data was evaluated for pseudo first-order, pseudo second-order and homogeneous particle diffusion models. The results showed that both the pseudo second-order and the homogeneous particle diffusion models were found to best correlate the experimental rate data.

Impact of alkali cations on properties of metakaolin and metakaolin/slag geopolymers: Microstructures in relation to sorption of 134Cs radionuclide.

Radio-cesium constitutes major environmental threats. Sorption of hazardous species onto geopolymeric sorbents is relatively recent and may give information about the retention mechanisms when geopolymers are applied to immobilize radwastes. Here, Na-MK, K-MK, Na-MKBFS, and K-MKBFS geopolymeric sorbents were synthesized from metakaolin (MK) and blast furnace slag (BFS) and were characterized using XRD, XRF, FT-IR, DTA/TGA and SEM. FT-IR/XRF results clarified the impact of mono-valent alkali cation (M+) in dividing the sorbents into Al-rich (sodium-based) and Si-rich (potassium-based). All sorbents were amorphous to semi-crystalline containing mica-phyllosilicates (greater in Si-rich), tobermorites (greater in MKBFS-based), gehlenite, calcite, quartz, hematite and hydrotalcite. Isotherms of 134Cs radionuclide sorption were constructed, being regular with a positive temperature effect. Al-rich sorbents gave higher sorption capacities than Si-rich ones. Na-MK sorbent recorded the more distinctive sorption capacity (74.95mg/g; at 333K). Langmuir, Freundlich and D-R models were used to disclose the capacities and mechanisms governing the sorption processes. Sorption of Cs+ onto the examined sorbents was favorable. All systems were controlled by ion exchange mechanism, except 134Cs/K-MK system which was controlled by physi- sorption mechanism. 134Cs/Na-MK GP system was the only spontaneous among all. The endothermic natures were the common denominator between the tested systems.

Clinical and microbiological efficacy of MDT in the treatment of diabetic foot ulcers.

OBJECTIVE: To assess the clinical and microbiological efficacy of maggot debridement therapy (MDT) in the management of diabetic foot ulcers unresponsive to conventional treatment and surgical intervention. METHOD: Consecutive diabetic patients with foot wounds presenting at the vascular surgery unit and the diabetic foot unit of Alexandria Main University Hospital were selected for MDT. Lucilia sericata medicinal maggots were applied to the ulcers for three days per week. Changes in the percentage of necrotic tissue and ulcer surface area were recorded each week over the 12-week follow-up period. Semiquantitative swab technique was used to determine the bacterial load before and after MDT. RESULTS: The sample comprised 10 patients with 13 diabetic foot ulcers. The mean baseline ulcer surface area was 23.5cm2 (range 1.3-63.1), and the mean percentage of necrotic tissue was 74.9% (range 29.9-100). Complete debridement was achieved in all ulcers in a mean of 1.9 weeks (range 1-4). Five ulcers (38.5%) were completely debrided with one three-day MDT cycle. The mean reduction in ulcer size was significant at 90.2%, and this occurred in a mean of 8.1 weeks (range 2-12). The mean weekly reduction in ulcer size was 16.1% (range 8.3-50). Full wound healing occurred in 11 ulcers (84.6%) within a mean of 7.3 weeks (range 2-10). The bacterial load of all ulcers reduced sharply after the first MDT cycle to below the 10(5) threshold, which facilitates healing. CONCLUSION: The results highlight the potential benefits of MDT in diabetic wound care in developing countries. MDT was proved to be a rapid, simple and efficient method of treating these ulcers.

Mono- and co-substrate utilization kinetics using mono- and co-culture of Clostridium beijerinckii and Clostridium saccharoperbutylacetonicum.

The effect of co-culturing C. beijerinckii and C. saccharoperbutylacetonicum for H2 production using mono- and co-substrates of glucose, starch, and cellulose was assessed. Monod kinetic parameters (K, maximum specific substrate utilization rate; and Ks, half-saturation constant) of the C. beijerinckii, C. saccharoperbutylacetonicum, and the co-culture were determined. Co-cultures utilizing glucose competed for the substrate, but showed enhancement for utilizing starch. The maximum values for K on glucose and starch were 0.48g substrate/gVSS.h achieved by C. saccharoperbutylacetonicum mono-culture and 0.39g substrate/gVSS.h achieved by the co-culture, respectively. The average Ks for all mono- and co-culture experiments was 0.93±0.03g/L. Acetate, butyrate, and propionate were the main fermentation products for all experiments. Maximum H2 production yields on glucose (2.69mol/molglucose) and starch (1.07mol/molhexose) were achieved by C. beijerinckii and C. saccharoperbutylacetonicum mono-cultures, respectively; however, neither culture was able to degrade cellulose as a mono-substrate.

Carcinoembryonic antigen, alpha-fetoprotein, and prostate-specific antigen in the sera of industrial workers exposed to phenol, formaldehyde, urea, and mixed vapors.

Exposure to certain industrial agents has been thought to have carcinogenic potential, both for employees who work closely with agents and for the general population that comes into contact with them. The objective of the present study is to evaluate the changes at the cellular level or at the level of cellular metabolism products present in the biological fluid, and to detect early stages of the carcinogenic process resulting from the exposure of industrial environmental hazards. Carcinoembryonic antigen (CEA), alpha-fetoproteins (AFP), and prostate-specific antigen (PSA) were measured in sera of workers (n = 51), who were divided into 4 groups: group I, workers exposed to phenol; group II, workers exposed to formaldehyde; group III, workers exposed to urea; and group IV, workers exposed to mixed vapor, plus a reference control healthy group (n = 15). The results showed that 75% of the workers exposed to phenol, 75% of the workers exposed to urea, 83.3% of workers exposed to formalin, and 92.3% of the workers exposed to mixed vapors had raised values of serum CEA (S-CEA) above normal value of the control group. Also, 23% of workers exposed to mixed vapors, 44% of workers exposed to formalin, 50% of workers exposed to phenol, and 62.5% of workers exposed to urea had raised values of serum AFP (S-AFP) above normal value of control group. Finally, 16.6% of workers exposed to phenol, 23% of workers exposed to mixed vapors, and 33.3% of workers exposed to formalin had raised values of serum PSA (S-PSA) above the normal value of control group; there were no raised values of S-PSA in workers exposed to urea. No significant difference was found in the activities of AST and ALT in group I, but a highly significant increase was found in the AST activities for groups II and IV and the ALT activities for groups III and IV. A significant difference was found in the activity of ALT in group II and in AST for group III. There was no significant difference in the levels of albumin in groups I, II, and III, whereas albumin levels were significantly decreased in group IV. No significant change was found in the level of urea and creatinine in all groups except for group III, where serum levels of creatinine were significantly decreased. From our findings, we concluded that S-CEA can be used as an important prognostic screening marker for early prediction for malignancy, and for management of workers with lung cancer who are exposed to the environmental hazards in industrial factories. Furthermore, S-AFP can be used also as a biomarker if it is carried out and correlated with S-CEA.

Immobilization of cesium and strontium radionuclides in zeolite-cement blends.

Zeolites are preferred ion exchange materials for the removal of radioisotopes from aqueous nuclear wastes because of their selectivity, radiation and temperature stability, and good compatibility with the cement matrix. Loaded materials, which are not regenerated, are preferably embedded in a solid matrix prior to ultimate storage in a repository. The aim of the present study is to investigate the possibility of solidifying exhausted synthetic zeolite A, loaded with (137)Cs and/or (90)Sr radionuclides, in Ordinary Portland Cement (OPC). Several factors affecting the characteristics of the final solidified waste product towards safe disposal such as mechanical strength and leaching behavior of the radionuclides have been studied. A simplified mathematical model based on diffusion mechanism for cylindrical geometry waste matrix has been simulated to predict the release rates of the investigated radionuclides from cement matrix. The predicted values are discussed in relation to experimentally observed leach rates to confirm the proposed mechanism in the model. The obtained results showed that the presence of zeolite A in the final cemented wastes improve the mechanical characteristics of the solidified cement matrix (mechanical strength and setting times) towards the safety requirements and reduce considerably the radionuclides leach rates.

Performance of mesophilic biohydrogen-producing cultures at thermophilic conditions.

In this study, batch tests were conducted to investigate the performance of mesophilic anaerobic digester sludge (ADS) at thermophilic conditions and estimate kinetic parameters for co-substrate fermentation. Starch and cellulose were used as mono-substrate and in combination as co-substrates (1:1 mass ratio) to conduct a comparative assessment between mesophilic (37 °C) and thermophilic (60 °C) biohydrogen production. Unacclimatized mesophilic ADS responded well to the temperature change. The highest hydrogen yield of 1.13 mol H2/mol hexose was observed in starch-only batches at thermophilic conditions. The thermophilic cellulose-only yield (0.42 mol H2/mol hexose) was three times the mesophilic yield (0.13 mol H2/mol hexose). Interestingly, co-fermentation of starch-cellulose at mesophilic conditions enhanced the hydrogen yield by 26% with respect to estimated mono-substrate yields, while under thermophilic conditions no enhancement in the overall yield was observed. Interestingly, the estimated overall Monod kinetic parameters showed higher rates at mesophilic than thermophilic conditions.

Intercapillary distance measurement as an indicator of hypoxia in carcinoma of the cervix uteri.

The mean tumor intercapillary distance (ICD) was measured in 44 patients in Stages IIB and III carcinoma of the cervix uteri using a histo-chemical procedure for staining capillary endothelial cells. A mean ICD of 304 +/- 30 microns was obtained, which was independent of the clinical stage and histological grade of differentiation. For each tumor, the proportion of ICD's greater than an arbitrarily chosen value of 300 microns (approximately twice the maximum oxygen diffusion range) was calculated using the normal frequency distribution statistics. The mean ICD and this proportion decreased progressively during the course of external beam pelvic irradiation up to a dose of 4000 cGy. The mean ICD was greater in patients who suffered local recurrence within two years than in patients whose tumors remained controlled. This applied to pre-treatment values and measurements performed after the delivery of 2000 and 4000 cGy. The proportion of ICD's greater than 300 microns showed a similar trend. No significant correlation was found between the hemoglobin concentration at time of presentation and either the mean ICD, or the probability of local control. It is proposed that ICD measurement may be a useful tool to identify subgroups of tumors where hypoxia can interfere with the effectiveness of radiotherapy.