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PubMed1986

Reduced tar, nicotine, and carbon monoxide exposure while smoking ultralow- but not low-yield cigarettes.

An unresolved public health issue is whether some modern cigarettes are less hazardous than others and whether patients who cannot stop smoking should be advised to switch to lower-yield cigarettes. We studied "tar" (estimated by urine mutagenicity), nicotine, and carbon monoxide exposure in habitual smokers switched from their usual brand to high- (15 mg of tar), low- (5 mg of tar), or ultralow-yield (1 mg of tar) cigarettes. There were no differences in exposure comparing high- or low-yield cigarettes, but tar and nicotine exposures were reduced by 49% and 56%, respectively, and carbon monoxide exposure by 36% while smoking ultralow-yield cigarettes. Similarly, in 248 subjects smoking their self-selected brand, nicotine intake, estimated by blood concentrations of its metabolite cotinine, was 40% lower in those who smoked ultralow but no different in those smoking higher yields of cigarettes. Our data indicate that ultralow-yield cigarettes do deliver substantial doses of tar, nicotine, and carbon monoxide, but that exposures are considerably less than for other cigarettes.

Adult↗
PubMed1984

The apparent quantum yield of T-state human hemoglobin. Contribution of protein and heme to rates of oxygen reactions.

The apparent quantum yield for dissociation of oxygen from T-state human hemoglobin has been determined using pulses of light 350 ns long at 540 nm. Two quantum yields were found. One was the same as for the R-state, and, like it, strongly temperature- and viscosity-dependent. The other, only slightly influenced by temperature and viscosity, was 10 times larger at 20 degrees C. Previous work (Sawicki, C. A., and Gibson, Q. H. (1977) J. Biol. Chem. 252, 7538-7547) has shown two distinct phases in binding of oxygen by T-state human hemoglobin at pH 7, 20 degrees C. When the apparent quantum yield was followed with time, the species with high quantum yield correlated with the rapidly reacting T-state species. The hemoglobin chains have different quantum yields in the T-state. Quantum yield data may serve as a measure of population of the liganded T-state in human hemoglobin, supplementing absorbance and circular dichroism data, and permit calculation of the rates of reaction at the heme in both R- and T-states.

Chemical Phenomena↗
PubMed1978

To improve the yield of biopsy of the lymph nodes.

The diagnostic yield of 290 biopsies of thee lymph nodes performed between 1970 and 1974 was reviewed. A specific diagnosis was made in 63 per cent. In 10 per cent, the working diagnosis preoperatively was changed because of the biopsy. There was no significant variance in the postive yield obtained at the various biopsy sites. The surprisingly high yield from biopsy of inguinal lymph nodes was ascribed to a greater hesitancy on the part of th surgeon to do a biopsy of the nodes in the groin, unless they were strongly suggestive of disease. The highest yield rates were obtained when Boeck's sarcoidosis was suspected. Excellent yield rates were also obtained when the preoperative diagnosis was lymphoma or metastatic carcinoma. A protocol for handling the specimen was devised to maximize the potential yield of biopsy of the lymph nodes.

Adolescent↗
PubMed1995

Autologous progenitor cell transplantation: prior exposure to stem cell-toxic drugs determines yield and engraftment of peripheral blood progenitor cell but not of bone marrow grafts.

Agents with stem cell-toxic potential are frequently used for salvage therapy of Hodgkin's disease (HD) and high-grade non-Hodgkin's lymphoma (NHL). Because many patients with relapsed or refractory lymphoma are candidates for autologous progenitor cell transplantation, possible toxic effects of salvage chemotherapy on progenitor cells must be taken into account. In a retrospective study, we have analyzed the influence of a salvage regimen containing the stem cell-toxic drugs BCNU and melphalan (Dexa-BEAM) on subsequently harvested bone marrow (BM)- and peripheral blood-derived progenitor cell grafts (PBPC) and compared it with other factors. Progenitor cells were collected from 96 patients with HD or high-grade NHL. Seventy-nine grafts were reinfused (35 PBPC and 44 BM) after high-dose chemotherapy. Compared with patients autografted with BM, hematopoietic recovery was significantly accelerated in recipients of PBPC. For PBPC, the number of Dexa-BEAM cycles ( > or = v > 1) was the predominate prognostic factor affecting colony-forming unit-granulocyte-macrophage (CFU-GM) yield (66 v 6.8 x 10(4)/kg, P = .0001), CD34+ cell yield (6.6 v 1.6 x 10(6)/kg, P = .0001), neutrophil recovery to > 0.5 x 10(9)/L (9 v. 11 days, P = .0086), platelet recovery to > 20 x 10(9)/L (10 v 15.5 days, P = .0002), and platelet count on day +100 after transplantation (190 v 107 x 10(9)/L, P = .031) using univariate analysis. Previous radiotherapy was associated with significantly lower CFU-GM and CD34+ cell yields but had no influence on engraftment. Patient age, patient sex, disease activity, or chemotherapy other than Dexa-BEAM did not have any prognostic impact. Multivariate analysis confirmed that Dexa-BEAM chemotherapy was the overriding factor adversely influencing CFU-GM yield (P < .0001), CD34+ cell yield (P < .0001), and platelet engraftment (P < .0001). BM grafts were not significantly affected by previous Dexa-BEAM chemotherapy or any other variable tested. However, prognostic factors favoring the use of BM instead of PBPC were not identified using joint regression models involving interaction terms between the graft type (PBPC or BM) and the explanatory variables investigated. We conclude that, in contrast to previous radiotherapy or other chemotherapy, exposure to salvage regimens containing stem cell-toxic drugs, such as BCNU and melphalan, is a critical factor adversely affecting yields and performance of PBPC grafts. Marrow progenitor cells appear to be less sensitive to stem cell-toxic chemotherapy. PBPC should be harvested before repeated courses of salvage chemotherapy involving stem cell-toxic drugs to preserve the favorable repopulation kinetics of PBPC in comparison with BM.

Adolescent↗
PubMed1994

Effects of postirradiation temperature on the yields of radiation-induced single- and double-strand breakage in SV40 DNA.

The effects of postirradiation holding temperature on the yields of radiation-induced single- and double-strand breaks (SSBs and DSBs) in SV40 DNA have been measured by agarose gel electrophoresis. When the DNA is held at low temperatures (< or = 2 degrees C) before and during electrophoresis, the measured yields of radiation-induced SSBs and DSBs are twofold less than in samples exposed to room temperature. In contrast, if the DNA is incubated at 37 degrees C overnight, the yield of DSBs increases twofold over the room temperature assay, while the SSB yield increases only to a small extent (< or = 20%). From a comparison of the various yields, we suggest that low temperature stabilizes radiation-induced labile sites, and that the increased yield of DSBs at 37 degrees C is due either to the recruitment of spatially separate SSBs as DSBs by duplex melting, or to labile sites generating DSBs. The different routes to DSB formation are kinetically distinct. We conclude that room-temperature electrophoresis measures all SSBs including those from labile sites.

Cell Line↗
PubMed1999

Diagnostic yield of the comprehensive assessment of developmental delay/mental retardation in an institute of child neuropsychiatry.

The Consensus Conference of the American College of Medical Genetics has established guidelines regarding the evaluation of patients with mental retardation (MR) [Curry et al., Am. J. Med. Genet. 72:468-477, 1997]. They emphasized the high diagnostic utility of cytogenetic studies and of neuroimaging in certain clinical settings. However, data on the diagnostic yield of these studies in well-characterized populations of individuals with MR are scant. Majnemer and Shevell [J. Pediatr. 127:193-199, 1995] attained a diagnostic yield of 63%. However, this study included only 60 patients and the classification included pathogenetic and causal groups. The Stella Maris Institute has evaluated systematically patients with developmental delay (DD)/MR and performed various laboratory studies and neuroimaging in almost all patients. We report a retrospective analysis of the diagnostic yield of 120 consecutive patients observed at our Institute during the first 6 months of 1996. There were 77 males and 43 females; 47 were mildly delayed (IQ 70-50), 31 were moderately delayed (IQ 50-35), and 42 were severely delayed (IQ 35-20). Diagnostic studies (history, physical examination, standard cytogenetics, fragile X testing, molecular studies, electroencephalography, electromyography, nerve conduction studies, neuroimaging, and metabolic screening tests) yielded a causal diagnosis in 50 (41.6%) and a pathogenetic diagnosis in 47 (39.2%) of the 120 patients. Causal categories included chromosomal abnormalities (14), Fra(X) syndromes (4), known MCA/MR syndromes (19), fetal environmental syndromes (1), neurometabolic (3) disorders, neurocutaneous (3) disorders, hypoxic-ischemic encephalopathy (3), other encephalopathies (1), and congenital bilateral perisylvian syndrome (2). Pathogenetic categories included idiopathic MCA/MR syndromes (35), epileptic syndromes (10), and isolated lissencephaly sequence (2). Diagnostic yield did not differ across categories and degree of DD. Our results, while confirming the diagnostic utility of cytogenetic/molecular genetic, and neuroimaging studies, suggest the usefulness of accurate electroencephalogram recordings, and stress the importance of a thorough physical examination. Referral to a university child neurology and psychiatry service, where a comprehensive assessment with a selected battery of investigations is possible, yields etiologic findings in a high percentage of DD/MR patients, with important implications for management, prognosis and recurrence risk estimate.

Adolescent↗
PubMed2026

From stress signaling to yield stability: physiological and molecular mechanisms of wheat resilience to heat and drought stress.

Wheat resilience depends on coordinated signaling, reproductive protection, and source-sink regulation, providing a framework to breed robust trait combinations that stabilize yield under combined heat and drought. Climate change is increasing the frequency and severity of heat and drought events, posing a major threat to wheat productivity, yield stability, and food security. Because these stresses often coincide in the field, their combined effects can impair growth, reproductive development, grain filling, and final yield more severely than either stress alone. Wheat resilience under such conditions depends on coordinated physiological adjustment and molecular regulation that sustain cellular homeostasis, protect reproductive tissues, and preserve yield-related traits. This review synthesizes current knowledge on the physiological and molecular bases of wheat resilience to heat and drought, with emphasis on their combined effects. We discuss major physiological responses, including photosynthetic adjustment, stomatal regulation, canopy cooling, osmotic balance, antioxidant defense, membrane stability, and source-sink coordination. We also examine key regulatory pathways involved in stress perception and adaptation, including calcium and reactive oxygen species signaling, mitogen-activated protein kinase cascades, phytohormonal crosstalk, transcriptional regulation, heat shock proteins, late embryogenesis abundant proteins, and osmoprotective and redox-associated pathways. In addition, we highlight the growing contribution of transcriptomics, proteomics, metabolomics, and phenomics to the identification of candidate genes, biomarkers, and adaptive traits. Finally, we consider how mechanistic insights can be translated into wheat improvement through molecular markers, genomic selection, gene editing, and climate-realistic phenotyping. An integrated understanding of stress signaling and adaptive trait deployment will be essential for developing wheat cultivars with improved resilience and yield stability under future climates.

Triticum↗
PubMed2025

A meta-analysis of diagnostic yield and clinical utility of genome and exome sequencing in pediatric rare and undiagnosed genetic diseases.

PURPOSE: To systematically evaluate the diagnostic yield and clinical utility of genome sequencing (GS) and exome sequencing (ES; genome-wide sequencing [GWS]) in pediatric patients with rare and undiagnosed genetic diseases. METHODS: We conducted a meta-analysis of studies published between 2011 and 2023. To address study heterogeneity, comparative analyses included within-cohort studies using random-effects models. RESULTS: We identified 108 studies including 24,631 probands with diverse clinical indications. The pooled diagnostic yield among within-cohort studies (N = 13) for GWS was 34.2% (95% CI: 27.6-41.5; I2: 86%) vs 18.1% (95% CI: 13.1-24.6; I2: 89%) for non-GWS, with 2.4-times odds of diagnosis (95% CI: 1.40-4.04; P < .05). The pooled diagnostic yield among within-cohort studies (N = 3) for GS was 30.6% (95% CI: 18.6-45.9; I2: 79%) vs 23.2% (95% CI: 18.5-28.7; I2: 58%) for ES, with 1.7-times the odds of diagnosis (95% CI: 0.94-2.92; P = .13). In first-line testing, the diagnostic yield tended to be higher for GS than for ES across clinical subgroups. The pooled clinical utility among patients with a positive diagnosis was 58.7% (95% CI: 47.3-69.2; I2: 81%) for GS and 54.5% (95% CI: 40.7-67.6; I2: 87%) for ES. CONCLUSION: GS appears to have a higher diagnostic yield than ES, with similar clinical utility per positive diagnosis.

Child↗
PubMed2026

Investigating the Role of MicroRNA396 (miR396) Gene in Regulating Wheat Yield and Grain Nitrogen Concentration.

Nitrogen (N) is essential for crop growth, yet excessive fertilization causes environmental issues, highlighting the need to sustain yield and grain N concentration under reduced N input. miR396s are known to regulate plant development and stress responses. Here, we examined whether and how miR396 affects wheat yield and N status under high and low N conditions. TaMIM396 (transforming with the target mimicry construct of miR396) overexpression significantly increased plant height, spike length, grain yield, and grain N concentration under both N treatments. Physiological data showed TaMIM396 enhanced dry matter (DM) and N accumulation at anthesis and maturity, as well as improved post-anthesis remobilization of DM and N to grains. RNA-seq analysis revealed that, under low N, TaMIM396 specifically upregulated key photosynthetic antenna genes, including Lhca3 and Lhcb1/2/3/5, which are critical for light harvesting, suggesting improved photosynthetic efficiency that promotes DM accumulation under N limitation. Collectively, our results demonstrate that TaMIM396 acts as a broad-spectrum N-efficiency gene, coordinating carbon and N remobilization while boosting photosynthetic capacity, thereby supporting stable yield and grain N concentration across N supply levels. Therefore, TaMIM396 is a promising candidate for breeding N-efficient wheat cultivars compatible with sustainable high-yield agriculture.

TaMIM396↗
PubMed2002

Yield prediction and stoichiometry of multi-step biodegradation reactions involving oxygenation.

Microorganisms can initiate the degradation of organic compounds by oxygenation reactions that require the investment of energy and electrons. This diversion of energy and electrons away from synthesis reactions leads to decreased overall cell yields. A thermodynamic method was developed that improves the accuracy of cell yield prediction for compounds degraded through pathways involving oxygenation reactions. This method predicts yields and stoichiometry for each step in the biodegradation pathway, thus enabling modeling a multi-step biodegradation process in which oxygenations occur and intermediates may persist. EDTA and benzene biodegradation are presented as examples. The method compares favorably with other yield prediction methods while providing additional information of yields for intermediates produced in the degradation pathway.

Benzene↗
PubMed2006

Analysis of the maximum theoretical yield for the synthesis of erythromycin precursors in Escherichia coli.

The heterologous biosynthesis of complex polyketides in Escherichia coli was recently achieved through metabolic engineering. However, it was observed that less than 10% of the propionate carbon source is transformed into the erythromycin precursor, 6-deoxyerythronolide B (6dEB), resulting in a 1.4% molar yield. Therefore, metabolic flux analysis was performed using a model of the Escherichia coli metabolism with the addition of the enzymes required for 6dEB synthesis. The analysis shows that the maximum theoretical yield for 6dEB synthesis in E. coli is 11%. The maintenance energy requirement of E. coli and limitations in the specific oxygen uptake rate can further decrease the yield, suggesting that the observed 6dEB yield of 1.4% can be the result of these two factors. In addition, the results suggest that an increase in the specific carbon and oxygen uptake rates will increase the yield of 6dEB. The use of glucose as an alternative carbon source was also evaluated using metabolic flux analysis and the results suggest that the choice of glucose as the carbon source will allow a small improvement in performance relative to a propionate-based process.

Anti-Bacterial Agents↗
PubMed1976

Bacterial yields on methanol, methylamine, formaldehyde, and formate.

Several bacteria utilizing C1-compounds as sole carbon sources were grown on these substrates in continuous culture. The molar yield values (g of cell dry wt/mol of substrate utilized) of bacteria which utilize C1-compounds via the ribulose monophosphate pathway were between 15.7 to 17.3 when grown on methanol; while the molar yield values of bacteria which use the serine pathway for the assimilation of C1-compounds varied between 9.8 and 13.1. The molar yield values of different bacteria which use the serine pathway decreased as the oxidation levels of the C1-growth substrates increased. On formaldehyde the values were between 7.2 to 9.6, whereas on formate the values varied from 3.3 to 6.9. It appears that bacteria utilize C1-compounds more efficiently via the ribulose monophosphate pathway than via the serine pathway. The oxidation step from methanol to formaldehyde (and from methylamine to formaldehyde) in the bacteria studied may be energy yielding. A comparison has been made between the experimental yield values obtained and theoretical values.

Formaldehyde↗
PubMed2003

Yield of endoscopic ultrasound-guided fine-needle aspiration biopsy in patients with suspected pancreatic carcinoma.

BACKGROUND: Although atypical or suspicious cytology may support a clinical diagnosis of a malignancy, it is often not sufficient for the implementation of therapy in patients with pancreatic carcinoma. Endoscopic ultrasound-guided fine-needle aspiration biopsy (EUS-FNAB) is a relatively new method for obtaining cytology samples, and one that may decrease the number of atypical/suspicious diagnoses. The goals of the current study were to prospectively evaluate the yield of EUS-FNAB in the diagnosis of patients presenting with solid pancreatic lesions and to evaluate the significance of atypical, suspicious, and false-negative aspirates. METHODS: All patients who presented with a solid pancreatic lesion and underwent EUS-FNAB over a 13-month period were included in the current study. One endoscopist performed all EUS-FNABs. On-site evaluation of specimen adequacy by a cytopathologist was available for each case. Follow-up included histologic correlation (n = 21) and clinical and/or imaging follow-up (n = 80), including 38 patients who died of the disease. RESULTS: EUS-FNABs were obtained from 101 patients (mean age, 62 +/- 11.8 years; age range, 34-89 years). The male-to-female ratio was 2:1. Sixty-five percent of the lesions were located in the head of the pancreas, 12% were located in the uncinate, 17% were located in the body, and 6% were located in the tail. The mean size of the tumors was 3.3 cm (range, 1.3-7 cm). A median of 4 needle passes were performed (range, 1-11 needle passes). Sixty-two biopsies (61.4%) were interpreted as malignant on cytologic evaluation, 5 (5%) as suspicious for a malignancy, 6 (5.9%) as atypical/indeterminate, and 26 (25.7%) as benign processes. Of the 76 malignant lesions, 71 were adenocarcinomas, 3 were neuroendocrine tumors, 1 was a lymphoma, and 1 was a metastatic renal cell carcinoma. All except one of the suspicious/atypical aspirates were subsequently confirmed to be malignant. Agreement was complete for the atypical cases. Among the suspicious cases, 2 of the 5 were identified as carcinoma by one cytopathologist and as suspicious lesions by the other, yielding a 40% disagreement rate between the 2 cytopathologists. Therefore, for the 10 atypical or suspicious cases that later were confirmed to be malignant, the final diagnosis of malignant disease was not made due to scant cellularity that could be attributed to sampling error in 8 cases and to interpretative disagreement in 2 cases (20%). All four false-negative diagnoses were attributed to sampling error. Two percent of all biopsies were inadequate for interpretation. Of the 99 adequate specimens, 72 yielded true-positive results, 23 yielded true-negative results, and 4 yielded false-negative results. No false-positives were encountered. Therefore, the sensitivity, specificity, positive predictive value, and negative predictive value of EUS-FNAB for solid pancreatic masses were 94.7% (95% confidence interval [CI], 89.7-99.8%), 100%, 100%, and 85.2% (95% CI, 71.8-98.6%), respectively. CONCLUSIONS: EUS-FNAB is a safe and highly accurate method for tissue diagnosis of patients with solid pancreatic lesions. Patients with suspicious and atypical EUS-FNAB aspirates deserve further clinical evaluation.

Adult↗
PubMed1994

Isolation of porcine pancreatic islets: low trypsin activity during the isolation procedure guarantees reproducible high islet yields.

During the past few years, interest in xenotransplantation of porcine islets of Langerhans for the future therapy of type I diabetes has increased markedly. Therefore, we established a semiautomated digestion method for isolating islets from the porcine pancreas. However, although the isolation technique was standardized and collagenase of controlled quality was used, we were unable to attain high islet yields with a satisfactory degree of reproducibility. One hypothesis was that varying degrees of interference by donor pancreatic enzymes were responsible for this failure. The aim of this study was to examine the kinetics of four types of enzymatic activity during the isolation procedure, as well as their effects on islet yield: collagenase, trypsin, neutral protease, and clostripain. Our results indicate that while exogenous collagenase activity decreases slightly during the isolation procedure, the activity of the pancreas enzymes neutral protease and trypsin increases. In some cases, trypsin activity increases very strongly. A strong increase in trypsin activity correlates with poor islet yield, whereas low trypsin activity always correlates with high islet yield. Addition of the protease inhibitor Pefabloc to the isolation medium results in low trypsin activity and reproducible high islet yields.

Animals↗
PubMed2004

Request form history, clinical indication, and yield of brain magnetic resonance studies.

PURPOSE: To investigate whether improved clinical history allows the radiologist to better predict the pretest probability of obtaining a positive or negative result from a magnetic resonance (MR) examination. MATERIALS AND METHODS: Six neuroradiologists prospectively reviewed 100 consecutive requests for brain MR examinations and sequentially assessed 1) quality of written history, 2) degree of indication for requested study, and 3) any pertinent new information found during chart review that may have altered the degree of indication. MR yield was correlated with the degree of indication assessed before and after chart review. RESULTS: Most request form histories were judged as poor (63%), and chart review reduced the overall indications for MR examinations, as there was a tendency for high-indication requests to migrate to the low-indication category. Based on request form history alone, the yields for low- and high-indication studies were 13% and 37%, respectively. Correlations between MR yield and indication after chart review improved significantly (P < 0.05) with 2% and 61% for low and high indications, respectively. Sensitivity and specificity for a positive MR yield were 71% and 62%, respectively, for the indication judged by the request history alone, and 96% and 80%, respectively, after chart review. Positive and negative prediction rates were 37% and 87%, respectively, for the indication judged by the request history alone, and 61% and 98%, respectively, for the indication judged after chart review. CONCLUSION: Based on our limited data, most request form histories were inadequate, and essential information available in the chart before MR examinations was frequently missing from the request forms. When adequate information was provided, the indication for the studies as judged by the radiologists predicted the MR yield more accurately, particularly for those requests with low indication. Therefore, our study suggests that MR imaging (MRI) may be used more effectively when pertinent clinical history is available. However, our study is limited and further studies are needed to confirm our results.

Adolescent↗
PubMed1994

The Titan haze revisited: magnetospheric energy sources and quantitative tholin yields.

We present laboratory measurements of the radiation yields of complex organic solids produced from N2/CH4 gas mixtures containing 10 or 0.1% CH4. These tholins are thought to resemble organic aerosols produced in the atmospheres of Titan, Pluto, and Triton. The tholin yields are large compared to the total yield of gaseous products: nominally, 13 (C + N)/100 eV for Titan tholin and 2.1 (C + N)/100 eV for Triton tholin. High-energy magnetospheric electrons responsible for tholin production represent a class distinct from the plasma electrons considered in models of Titan's airglow. Electrons with E > 20 keV provide an energy flux approximately 1 x 10(-2) erg cm-2 sec-1, implying from our measured tholin yields a mass flux of 0.5 to 4.0 x 10(-14) g cm-2 sec-1 of tholin. (The corresponding thickness of the tholin sedimentary column accumulated over 4 Gyr on Titan's surface is 4 to 30 m.) This figure is in agreement with required mass fluxes computed from recent radiative transfer and sedimentation models. If, however, these results, derived from experiments at approximately 2 mb, are applied to lower pressure levels toward peak auroral electron energy deposition and scaled with pressure as the gas-phase organic yields, the derived tholin mass flux is at least an order of magnitude less. We attribute this difference to the fact that tholin synthesis occurs well below the level of maximum electron energy deposition and to possible contributions to tholins from UV-derived C2-hydrocarbons. We conclude that Titan tholin, produced by magnetospheric electrons, is alone sufficient to supply at least a significant fraction of Titan's haze--a result consistent with the fact that the optical properties of Titan tholin, among all proposed materials, are best at reproducing Titan's geometric albedo spectrum from near UV to mid-IR in light-scattering models.

Aerosols↗
PubMed2002

Zeta potentials and yield stresses of silica suspensions in concentrated monovalent electrolytes: isoelectric point shift and additional attraction.

The zeta potentials and yield stresses of silica suspensions were measured over a wide range of monovalent electrolyte concentrations. The counterions investigated were Li(+), Na(+), K(+), and Cs(+), while the co-ion was always Cl(-). The poorly hydrated ions (Cs(+) and K(+)) adsorb in greater quantity to the silica surface than the well-hydrated ions (Li(+) and Na(+)) and produce lower magnitude negative zeta potentials at high pH. At high electrolyte concentrations and at low pH the poorly hydrated counterions adsorb in great enough quantity to reverse the sign of the zeta potential from negative to positive. This specific adsorption of counterions shifts the iep to higher values. The shift in the iep is directly related to the hydration of the counterion with the least hydrated ions creating the greatest iep shift. The yield stresses of silica suspensions at high pH were found to increase in the order Li(+)<Na(+)<K(+)<Cs(+). The magnitude of the yield stress correlates with the amount of adsorbed ions; i.e., the greatest yield stresses are observed with the least hydrated ions. The yield stresses measured at high pH with high salt concentrations are greater than can be accounted for with just van der Waals attraction. An attractive ion-ion correlation force is presumed responsible for the additional attraction necessary to explain the observed results.

Journal Article↗
PubMed1981

Cell yield and bioenergetics of Thiomicrospira denitrificans compared with Thiobacillus denitrificans.

From cell yields of Thiomicrospira denitrificans grown inthe chemostat at different growth rates under anaerobic conditions a value of 1.4 mM S2O3 = per g dry wt and per h could be calculated for maintenance energy requirements, and of 5.65 dry wt per mole S2O3 = for the true growth yield. Cell yields of Thiomicrospira denitrificans appeared to be almost half of those of Thiobacillus denitrificans. Though in Thiobacillus denitrificans at D = 0.03 h(-1) under anaerobic conditions a value was found of 11.60 g dry wt per mole of thiosulphate used for energetic purposes, a value of 5.72 g dry wt per mole of thiosulphate was found under comparable conditions in Thiomicrospira denitrificans. Under aerobic conditions at D = 0.03 h(-1) values of 18.54 g dry wt per mole of thiosulphate were found in Thiobacillus denitrificans whereas Thiomicrospira denitrificans yielded only 9.38 g dry wt per mole of thiosulphate. As in Thiobacillus denitrificans anaerobic cell yields on sulphide were comparable to those on thiosulphate. Calculations have been made which indicate that the biosynthetic efficiency of Thiomicrospira denitrificans is lower than that of Thiobacillus denitrificans. This can only partly be explained by the absence of adenosine-phosphosulphate (APS) reductase.

Adenosine Triphosphate↗