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PubMed1995

[Use and yield of microbiological diagnosis of sexually transmitted Chlamydia trachomatis infections in Vestfold 1984-93].

Testing for Chlamydia trachomatis has become widely available in Norway during the last ten years. We have evaluated the number and yield of tests in Vestfold county. The number of performed tests increased from 0.6 per 100 inhabitants in 1984 to 6.5 in 1993, while the yield declined from 14.7% to 3.4%. The incidence of diagnosed infection declined from 4.0 per 1,000 person-years in 1988 to 2.2 in 1993. In 1991, 59.6% of the samples were taken from women aged 15 to 29 years. Male patients provided 7.1% of the samples. Between 40 and 50 tests were performed among every 100 Vestfold women in their twenties. More than three quarters of the positive tests were found in women under 25 years of age or in men. Women 30 years of age or older accounted for 32.4% of the tests, but only 9.3% of the positive tests; reaching a yield of less than 1.1%. We recommend that doctors perform fewer screening tests in women older than 25 years and more tests in men following notification by partner. This will increase the yield and reduce the number of false positive tests.

Adolescent↗
PubMed1995

[Effect of the duration of temporary drying off of one udder quarter in cows and milk yield and quality].

In this study the influence of temporary drying off of one udder quarter regarding milk production and milk quality of lactating and udder healthy cows was examined. The milk yield and milk composition (fat, protein, lactose and somatic cells) produced by each quarter was determined at day 1 until day 7 by use of a special designed milking machine to measure the milk yield of each quarter (control period). From day 8 to 17, the right front = rf (group 1, 6 cows) and left hind = Ih (group 2, 6 cows) quarters respectively were dried off without using any antibiotics for a period of 10 days. The rf (group 3, 5 cows) and Ih (group 4, 6 cows) quarter were dried off without using any antibiotics from day 8 to 10, day 12 to 14 and day 16 to 18. The lactating quarters were milked daily and the examination of the milk was carried out as during the control period. By the end of the experiment (day 41) the milk yield of the dried off udder quarters was only 60-80% of the levels examined during the control period. Therefore no difference concerning the milk yield between all animal tested was observed. The remaining parameters checked approached the levels in the mean range within 10 days after drying off. Bacteriologically the milk samples of udder quarters of group 1 and 2 remained sterile and in milk samples of quarters of group 3 and 4 gram-positive cocci could be isolated.

Animals↗
PubMed1995

Factors affecting the formation and yield of heterocyclic amines.

The main food mutagens found in cooked meat products are heterocyclic amines. The formation of these heterocyclic amines has been shown to require three classes of precursors: (i) creatine/creatinine, (ii) free amino acids or dipeptides, and (iii) sugar. The mutagen forming reactions were investigated in model systems and several heterocyclic amines (IQx, MeIQx, DiMeIQx, TriMeIQx and PhIP) were identified and quantified. A number of mutagenic fractions produced in the model system are not yet identified, among them one having a mass number of 217. A participation of the Maillard reaction in the formation of the heterocyclic amines was proposed ten years ago. Since then, the support for this route has increased, especially in a recent study in which carbon atoms from 14C-labelled glucose were shown to be incorporated into MeIQx and DiMeIQx. Other studies have shown sugar to either enhance or inhibit the yield of mutagenic activity depending on its molar ratio relative to the other reactants. Thus, the Maillard reaction can be utilized both to enhance and inhibit the formation of the heterocyclic amines. Olive oil and corn oil were found to almost double the yield of MeIQx in the model system after heating for 30 minutes at 180 degrees C. When adding deep-fat frying oil of different oxidation status in the model system, the yield of MeIQx was not affected by oxidation status or presence of vitamin E, but the lipids enhanced the formation of MeIQx by 30% after heating at 180 degrees C for 30 minutes. Artificial production of free radical reactions by adding FeSO4, hydrogen peroxide and oxygen to the model system doubled the yield of MeIQx.

Carcinogens↗
PubMed1998

The photobiological differences of gilvocarcins V and M are not related to their transient intermediates and triplet yields.

The transient absorption spectra of the intermediates produced by the 355 nm laser excitation of gilvocarcin derivatives have been investigated in various solvents. The spectra consist of a triplet-triplet absorption in the visible region and a residual absorption observed between 340 and 700 nm due to a long-lived species, assigned to the radical cation. A broad-fast decaying band with a maximum at around 700 nm attributed to the solvated electron is also seen in solutions containing a low DMSO/water volume ratio and at 266 nm irradiation of a 50% methanol/water solvent mixture. The molar absorption coefficient of the triplet state of gilvocarcin V (GV) and gilvocarcin M (GM), determined by the energy transfer method, is independent of the solvent properties and has a value of 3.0 x 10(4)/Mcm. The triplet decay rate constants for both drugs are between 1 and 5 x 10(4)/s. A similar initial yield and triplet decay rate constant of GV were observed in the presence of 3.4 mM thymine. Thus, a quenching rate constant of the GV's triplet state by thymine is estimated to be lower than 10(6)/Ms. The triplet quantum yields of both antibiotics determined by using the comparative method are higher in dimethylsulfoxide (DMSO) (0.18) than are those corresponding to 25% DMSO/water (0.06). The decrease in phi T in the presence of water could be attributed to an enhanced internal conversion rate constant from the S1 state or to an increase in the photoionization yield. The similarity of the transient intermediates and their yields for GV and GM suggest that their photobiological differences are due to other factors such as DNA binding constants, preferential localization of the drugs in the cell or the enhanced reactivity of the vinyl group toward cellular components.

Aminoglycosides↗
PubMed1998

The effect of prostate volume on the yield of needle biopsy.

PURPOSE: Early diagnosis of prostate carcinoma has undergone significant evolution mainly due to the widespread use of serum prostate specific antigen, transrectal ultrasonography and spring loaded biopsy devices. A common dilemma faced by clinicians arises when a negative biopsy is obtained in a patient and there is a high suspicion for prostate carcinoma. The literature reveals a 20 to 40% positive repeat biopsy rate in men with elevated prostate specific antigen who had an initial negative biopsy. We determined the yield of 6 systematic sector biopsies as a function of total gland and peripheral zone volumes. MATERIALS AND METHODS: The database of transrectal ultrasound guided prostate needle biopsies performed at the Department of Urology, University of Washington Medical Center and Veterans Affairs Puget Sound Health Care System was reviewed. The yield of the 6 biopsies was determined as a function of the total gland and peripheral zone volumes. RESULTS: A total of 1,057 men who underwent transrectal ultrasound guided prostate needle biopsies were investigated in our study. Of the men 326 were diagnosed with prostate cancer for a positive biopsy rate of 30.8%. No relationship between gland size and cancer yield was seen using total gland volume compared to the first quartile until the largest quartile when a significantly lower cancer detection rate was noted (odds ratio 1.5). CONCLUSIONS: The positive yield of the systematic 6-sector biopsy decreases significantly when the total gland volume is greater than 55.6 cc or peripheral zone volume is greater than 33.61 cc. In men with smaller prostates 6 systematic sector biopsies should be adequate.

Adult↗
PubMed2026

Molecular Bases and Genetic Design of Rice Disease Resistance for Optimized Yield and Sustainable Agriculture.

Rice diseases continue to undermine yield stability and threaten the sustainability of rice production. The central challenge is therefore not simply to maximize immune activation, but to identify genetic interventions that remain effective across diverse pathogen races and environmental conditions without imposing excessive penalties on growth or yield. Here, we synthesize the molecular basis of rice immunity from a design-oriented perspective. We first examine cell-surface pattern-recognition receptors and intracellular nucleotide-binding leucine-rich repeat receptors, and then assess the shared signaling hubs and defence outputs that connect pathogen perception to antimicrobial responses. Rather than treating these components as equivalent breeding targets, we compare their translational potential according to resistance spectrum, anticipated durability, tunability, pleiotropic risk, and the strength of field evidence. We further discuss breeding strategies based on receptor engineering, editing of susceptibility genes and cis-regulatory elements, post-translational motif engineering, pathogen-inducible and upstream open reading frame-mediated regulation, resistance-gene stacking and artificial intelligence-assisted prediction. We argue that rational resistance design in rice should move beyond constitutive immune activation toward allele-specific, quantitative, spatially restricted and infection-responsive regulation. Integrating mechanistic insights with precision genome editing, accelerated breeding and responsible deployment offers a practical route to durable, yield-compatible disease resistance while reducing dependence on chemical control.

breeding strategy↗
PubMed2026

Beyond the salt barrier: CRISPR-mediated DNA reprogramming to uncouple yield from tolerance in Rice: A review.

Rice (Oryza sativa L.) feeds half of humanity, yet its cultivation is increasingly threatened by soil salinization, which now affects 1.4 billion hectares globally. Decades of breeding and engineering have focused on Na+ exclusion, principally through the Saltol QTL and the xylem-unloading transporter OsHKT1;5, yet this strategy has reached a physiological ceiling. Excluder genotypes survive salinity but fail to fill grain, because the ATP-intensive cost of continuous ion extrusion starves reproductive sinks, while ABA-mediated stomatal closure imposes chronic carbon limitation. The resulting "survival-yield gap" exposes a fundamental flaw in single-trait approaches to a polygenic stress. In this review, we argue that durable, yield-stable salt tolerance requires a coordinated systems-level intervention spanning five mechanistic tiers: (i) CRISPR/Cas9-mediated removal of negative regulatory brakes (OsRR22, RST1, PC1) that suppress plant's latent stress-adaptive capacity; (ii) reinforcement of actin-myosin cytoskeletal transport to sustain SOS1, NHX1, and HKT1;5 delivery under ionic stress; (iii) importation of halophyte design principles from Oryza coarctata, including salt gland architecture and superior Na+ compartmentalization; (iv) recalibration of the ROS-photosynthesis axis via the DHHC09-STRK1-CatC molecular switch and stomatal density engineering; and (v) pyramiding these modules into a "Salt-Shield Rice" genotype through multiplex editing, marker-assisted introgression, speed breeding, and genomic selection. We propose a phased ten-year roadmap that integrates synthetic biology circuit design with conventional breeding to deliver field-ready, multi-module varieties with greater than 70% yield stability at 8-10 dS m-1. This remains an aspirational design target rather than a demonstrated outcome, as three of the five tiers-halophyte-derived structural traits, cytoskeletal reinforcement, and full multi-module pyramiding-remain unvalidated in rice.

CRISPR/Cas9↗
PubMed2026

The potential of considering photosynthesis parameters in crop yield breeding by genomic prediction.

To meet the growing demand for agricultural products, optimizing photosynthesis is a promising strategy to improve crop yields. Phenotypic variance in photosynthesis has been observed within or between species. To explore the potential of integrating photosynthetic parameters into crop breeding programs, we explored the genetic variation in photosynthesis by assessing photosynthesis-related parameters across plant development in 631 barley recombinant inbred lines (RILs) from eight HvDRR subpopulations under field conditions. The genetic complexity of these parameters was resolved by analyses of bi-parental and multi-parental quantitative trait loci (QTLs). Finally, we examined the merit of integrating photosynthesis-related parameters in genomic prediction of yield and its components. Significant genotypic variations of the photosynthesis-related parameters were found among the RILs, with their heritability ranging from 0.38 to 0.54. The multiple QTLs and dynamic QTLs for photosynthesis observed across different developmental stages underlined the complexity of the genetics of photosynthesis in barley. The considerably higher percentage of phenotypic variance explained for genomic prediction than multi-parental QTL analysis illustrates that the photosynthesis-related parameters are inherited in a more complex way than classical agronomic traits. Notably, the prediction ability for yield was increased by integrating the photosynthesis-related parameters of some developmental stages into genomic prediction models. Thus, our results suggest a novel perspective on increasing the efficiency of crop breeding programs by integrating photosynthesis-related parameters into prediction models.

Photosynthesis↗
PubMed2026

Pleiotropic mutation in a tendril TCP gene underlies the yield-enhancing multiple-flowering trait in summer squash (Cucurbita pepo).

Crop yield is a focal point in plant breeding. Regulation of lateral budding through apical dominance was a central target of crop domestication, directly affecting crop production. The young fruits of Cucurbita pepo, summer squash, are produced on plants characterized by apical dominance and differentiation of a single flower bud per leaf axil. A single recessive mutation, mf, results in differentiation of more than one flower per leaf axil, thereby directly increasing production because of the continual day-to-day harvest of the summer squash crop. Positional cloning of the Cucurbita pepo mf (Cpmf) gene denoted a frameshift mutation in a TCP transcription factor, Cp4.1LG13g07780, as causative for the increase in axillary flowering. Cpmf is an ortholog of a tendril-development TCP gene in other cucurbits, and likewise, the recessive allele of Cpmf is associated with distorted tendril development. Gene function is context dependent, and we propose that multiple flowering is a unique pleiotropic attribute of mutation in a tendril-development gene of C. pepo. Characterization of a C. pepo collection confirmed a significant association of the Cpmf mutation with multiple flowering and showed that the mutant allele is absent in ancestral C. pepo and one of its two cultivated subspecies. The beneficial mutation occurred and was selected after the domestication of the other subspecies, during its cultivation for young fruit production. We demonstrate the discovery of a causative yield-increasing sequence variant and its practical utilization in breeding. Our findings provide a molecular target for creation of high-yielding, multiple-flowering summer squash cultivars through marker-assisted breeding or precise genome editing.

Cucurbita↗
PubMed1998

The effects of more conservative neck dissections and radiotherapy on nodal yields from the neck.

OBJECTIVE: To determine the effects of conservative neck dissections (NDs) and preoperative radiotherapy on the quantitative recovery of lymph nodes from the neck. DESIGN: Retrospective review of case series. Data were obtained for age, preoperative TNM staging, type of ND, preoperative radiotherapy, total nodal yield (tNY), and positive nodal yield (pNY). The tNY and pNY were analyzed with factorial analysis of variance (ANOVA) to determine differences among types of ND and the effect of radiotherapy. SETTING: Tertiary care center for head and neck cancer. PATIENTS: Consecutive sample of 135 NDs in 110 patients with cancer of the head and neck. RESULTS: A significant difference in tNY was found among dissections (P<.001, ANOVA). Supraomohyoid ND had a significantly lower mean tNY (9.9 nodes) than both radical ND and modified radical ND (21.8 and 26.3 nodes, respectively; P<.05). Functional ND also had a significantly lower tNY (16.1 nodes) than modified radical ND (P<.05); the differences between radical ND and both functional ND and modified radical ND were not statistically significant. Positive nodal yield was not different among the types of dissections (P=.62). Preoperative radiotherapy significantly decreased mean tNY from 22.0 to 17.1 nodes (P=.02) over all types of dissections. Differences in tNY among dissection types were independent of the effect of radiotherapy. The presence or absence of preoperative radiotherapy had no significant effect on pNY (P=.18). CONCLUSIONS: Conservative modifications of the classic radical ND differ with respect to the quantity of cervical lymph nodes excised, but survival may not be altered since the pNY is not significantly different. When compared with the radical ND, the modified radical ND and functional ND do not compromise the quantity of cervical nodes excised. Radiotherapy significantly reduces the quantity of cervical nodes, but a significant number of nodes will still remain.

Adult↗
PubMed1997

Yield from stool testing of pediatric inpatients.

OBJECTIVES: To quantify the yield from stool testing in pediatric inpatients and to identify criteria to test stool more deliberately without sacrificing diagnostic sensitivity. DESIGN: A retrospective review was performed of all stool cultures, ova and parasite examinations, and Clostridium [correction of Clostridia] difficile toxin assays performed on pediatric inpatients, aged 3 days to 18 years, at Thomas Jefferson University Hospital, Philadelphia, Pa, for 1 year. Medical records were reviewed for positive cases, each with 2 controls matched for age and test type. For this study, the term admission refers to the interval between the times each patient was admitted to and discharged from the hospital. Some patients had multiple stool tests sent to the laboratory during a single admission; some patients had more than 1 admission during the study period. Statistical analysis was performed using X2 analysis and the Student 2-tailed t test with a commercially available statistical software package (Statworks, Cricket Software, Philadelphia). RESULTS: Of 250 patient admissions to the hospital for which stool was cultured, 7 cultures (2.8%) were positive. Of 63 patient admissions having ova and parasite testing, 1 (2%) had a positive result. Clostridium [correction of Clostridia] difficile toxin assays were performed on 40 patient admissions to the hospital, and 7 (18%) had a positive result. Only 18 (3.0%) of 598 of all test results reviewed were positive. Costs of negative test results totaled $26,084. More patients (71%) with positive stool cultures than control patients (21%) had a temperature higher than or equal to 38 degrees C (X2, P < .05); however, relying on this sign missed 29% of the children with bacterial infection. A white blood cell band count of at least 0.10 was 100% sensitive and 79% specific in identifying patients with positive stool culture. There was no statistically significant relationship between stool culture results and age, total white blood cell count or white blood cell segmented neutrophil count, and no relationship between C. difficile toxin assay results and any of the above characteristics. Clostridium [correction of Clostridia] difficile was the most common pathogen identified (6 of 9) in patients developing gastrointestinal symptoms after admission; however, Salmonella enteritidis and Shigella sonnei were also significant causes (3 of 9). CONCLUSIONS: There is low yield from stool testing of pediatric inpatients: C. difficile toxin assay has the highest yield. Clostridium [correction of Clostridia] difficile testing is most valuable for children with nosocomial gastrointestinal symptoms although other bacterial pathogens do cause nosocomial symptoms in children. More selective stool testing could help us be more efficient with our patient care resources.

Adolescent↗
PubMed2000

Aromatic interactions in homeodomains contribute to the low quantum yield of a conserved, buried tryptophan.

Trp 48, a conserved, buried residue commonly found in the hydrophobic core of homeodomains, has an unusually low fluorescence quantum yield. Chemical denaturation of Drosophila homeodomains Engrailed and Antennapedia(C39S) result in a four-fold increase in quantum yield, while unfolding of Ultrabithorax causes a twenty-fold enhancement. Global analysis of time-resolved fluorescence decay monitored at multiple emission wavelengths reveals sub-nanosecond lifetime components which dominate the overall intensity. Based on structure and sequence analysis of several homeodomains, we deduce that quenching is due to a transient, excited-state NH ellipsis pi hydrogen bond involving Trp 48 and a conserved aromatic residue at position 8. Additionally, both time-resolved fluorescence of indole-benzene mixtures and an electrostatic model of the proposed tryptophan-aromatic interaction substantiate different aspects of this mechanism. A survey of the Protein Data Bank reveals many proteins with tryptophan-aromatic pairs where the indole nitrogen participates in a NH ellipsis pi hydrogen bond with the ring of another aromatic residue. Chemical denaturation of one protein found in this survey, human fibronectin type III module 10, causes an enhancement of the fluorescence quantum yield. This unique interaction has implications for many other systems and may be useful for studying larger, multi-tryptophan containing proteins.

Animals↗
PubMed1999

Timing of platelet recovery is associated with adequacy of leukapheresis product yield after cyclophosphamide and G-CSF in patients with lymphoma.

A subgroup of patients with refractory Hodgkin's (HD) or non-Hodgkin's (NHL) lymphoma may be cured with high-dose chemotherapy and peripheral blood progenitor cell rescue. To investigate the relationship of adequate leukapheresis yield and time course of platelet recovery after mobilization chemotherapy, we retrospectively analyzed the leukapheresis yields in seven patients with Hodgkin's disease and fifteen patients with non-Hodgkin's lymphoma undergoing high-dose chemotherapy. Our goal was to develop a rule to determine when to initiate leukapheresis and then to prospectively validate this rule. All patients were mobilized with cyclophosphamide and G-CSF (granulocyte-colony stimulating factor). A total of 144 leukaphereses were completed and analyzed. Based on the CD34 content in the initial harvest product, fifteen patients were defined as poor mobilizers (CD34 < 0.15 x 10(6)/kg) and seven were good mobilizers. The platelet count on the first day of harvesting was significantly associated with the poor mobilizers (P = .03). Age, sex, marrow involvement, disease (HD vs. NHL), prior radiation, time since last chemotherapy, and total number of cycles of prior chemotherapy were not predictive of poor mobilizers. By using a platelet count cut off of 35 x 10(9)/L, we retrospectively analyzed 144 individual leukapheresis products, to test whether CD34 yield was predicted by the peripheral blood platelet count on the day of leukapheresis. This rule had an excellent sensitivity, 91%, and a specificity of 67%. Subsequently, we validated this rule with the next twenty-four patients undergoing leukapheresis of which there were 143 leukaphereses. The prediction rule exhibited a sensitivity of 72% and a specificity of 68% in the validation set. There does appear to be utility in using the platelet count to guide the initiation of leukapheresis after chemotherapy and G-CSF mobilization.

Adult↗
PubMed1994

Cost-effective prostate cancer detection. Reduction of low-yield biopsies. Investigators of the American Cancer Society National Prostate Cancer Detection Project.

BACKGROUND: In hopes of limiting low-yield prostate biopsies, results of digital rectal examination (DRE), transrectal ultrasound (TRUS), prostate specific antigen (PSA) and age-related PSA values, gland-volume-adjusted PSA levels, and longitudinal PSA changes were analyzed to identify their cost-effectiveness as prognostic indicators in screening, biopsy, and follow-up of patients with prostate cancer. METHODS: Twenty-nine hundred men with complete data sets from an initial cohort of 2999 men with an annual follow-up for up to 5 years were examined. Intrapatient PSA and gland-volume variability, optimal PSA operating points (o.p.), and test performance scores were determined for each parameter. Decision analysis was then applied retrospectively to each parameter to determine the cancer detection yield, biopsy requirements, and costs for commonly used detection strategies. RESULTS: For the initial screening decision, the optimal PSA o.p. was 3.0 ng/ml but increased to 5.0 ng/ml in combination with DRE, whereas age-related PSA performed no better than did PSA. The mean intrapatient variability in TRUS gland volume (+5.5 cc) relative to mean volume (34 cc) was 16%, which was less than the 28% (0.64/2.3 ng/ml) relative variability for PSA. For biopsy decisions, using PSA density (PSAD) with a level of 0.12 ng/ml/cc there was no significant difference in accuracy compared with the systematic biopsy of all patients with elevated PSA or age-related PSA levels. Rather than perform systematic biopsy on all patients with PSA levels greater than 4 ng/ml, decision analysis showed that a 16-55% reduction in biopsies could be achieved with a respective cancer loss of 4-25% by limiting biopsy to patients with an increased PSAD level and/or abnormal results of DRE. Using age-related PSA criteria in combination with DRE reduced biopsies by 12% but resulted in minimal cost reductions. The greatest biopsy reduction relative to cancer yield and lowest cost per cancer detected occurred with PSAD-driven biopsy strategies. During follow-up, longitudinal changes in absolute PSA and PSAD levels were significantly better (P < 0.05) than the percentage change in PSA levels per year. CONCLUSIONS: Cost-effective prostate cancer detection with PSA as a parameter is better achieved if screening and biopsy decisions are not linked intimately. A tailored-biopsy approach for patients with disproportionately elevated PSA levels of suspicious DRE results in the greatest biopsy reduction by selecting lower risk groups for more conservative follow-up.

Age Factors↗
PubMed2002

Effect of macerate enzymes on the yield, quality, volatile compounds and rheological property of prickly pear juice.

Pectinase and cellulase enzymes were used to investigate efficacy for improving juice yield, stability and quality from prickly pear fruit. Pectinase improved the yield, stable color, color-assayed as release of anthocyanins or carotinoids and clarity of the juice. A significant increase in the effectiveness of pectinase was observed as the concentration was increased from 0.05 to 0.50% v/w. However, at concentration > 0.25% v/w they tended to impart a bitter flavor in the juice. Among three concentrations of pectinase and cellulase, pectinase at 0.50% v/w produced higher yield, a sediment-free clear juice and high-quality juice. The results indicated that depectinated clarified prickly pear juice behaves as a Newtonian fluid. It was found that the activation energy (Ea) for viscous flow was in the range of 5.02 x 10(3)-20.06 x 10(3) kJ/mol depending on the concentrations of pectinase and cellulase enzyme treatment of prickly pear juice, in contrast to 22.15 x 10(3) kJ/mol in untreated juice. Volatile compound concentrations of twelve compounds were not affected by pectinase and cellulase treatment. Overall the quality of prickly pear juice was better in pectinase-treated juice compared with untreated and cellulase-treated juice.

Beverages↗
PubMed1997

Predicting wheat yields: the search for valid and precise models.

Interest in predicting wheat yield in terms of physiological, cultural and meteorological variables is more than a century old. Early attempts involved statistical analyses of relationships between yield and observational data on precipitation, temperature, radiation, etc., and scientific study of physiological and cultural influences such as dates of sowing or anthesis, farming procedures and soil treatments. More recently these have been augmented by large-scale mechanistic models of phenological development, such as AFRCWHEAT, CERES and SIRIUS, incorporating some simulation facilities. All approaches implicitly involve fitting models of some sort: statistical, mechanistic or (preferably) a hybrid of these forms. Levels of success on this important matter are highly variable. After reviewing the field, we consider the results of recent efforts to contrast and evaluate the (large-scale) mechanistic approaches, using spatial/temporal methods for interpolating the required climatological input variables. The work employs a substantial database of wheat yields assembled for this purpose. After assessing the validity of the large-scale mechanistic models (with some intriguing conclusions), we then consider some results from a current approach to parsimonious hybrid modelling, based on statistical study of accessible climatological data interpreted in terms of physiological knowledge of key influences on plant development.

Models, Biological↗
PubMed2025

Granular Hydrogels as Brittle Yield Stress Fluids.

While granular hydrogels are increasingly used in biomedical applications, methods to capture their rheological behavior generally consider shear-thinning and self-healing properties or produce ensemble metrics (e.g., dynamic moduli) while neglecting transient yielding and unyielding processes. Combining oscillatory shear testing with Brittility (Bt) via the Kamani-Donley-Rogers (KDR) model, this work shows that granular hydrogels behave as brittle yield stress fluids. This work quantifies steady and transient rheology as a function of microgel properties and granular composition for polyethylene glycol and gelatin microgels. The KDR model with Bt captures granular hydrogel behavior for a wide range of design parameters, reducing the complex rheology to a determination of model parameters. In granular mixtures, this work observes monotonic dependencies of the elastic modulus, structural viscosity, and brittility upon granular composition, while the yield stress is lower for mixtures. Microgel size distribution and polymer fraction are the most influential parameters in monolithic granular hydrogels, while microgel size and packing density are less impactful. The model robustly captures self-healing behavior and reveals that granular hydrogel relaxation accelerates with an increased small-amplitude strain rate. This quantitative framework is an important step toward rational design of granular hydrogels for applications ranging from injection and in situ stabilization to 3D bioprinting.

brittility↗
PubMed2002

Steam pressure disruption of municipal solid waste enhances anaerobic digestion kinetics and biogas yield.

Biomass waste, including municipal solid waste (MSW), contains lignocellulosic-containing fiber components that are not readily available as substrates for anaerobic digestion due to the physical shielding of cellulose imparted by the nondigestible lignin. Consequently, a substantial portion of the potentially available carbon is not converted to methane and the incompletely digested residues from anaerobic digestion generally require additional processing prior to their return to the environment. We investigated and developed steam pressure disruption as a treatment step to render lignocellulosic-rich biomass more digestible and as a means for increasing methane energy recovery. The rapid depressurization after steam heating (240 degrees C, 5 min.) of the nondigested residues following a 30-day primary digestion of MSW caused a visible disruption of fibers and release of soluble organic components. The disrupted material, after reinoculation, provided a rapid burst in methane production at rates double those observed in the initial digestion. This secondary digestion proceeded without a lag phase in gas production, provided approximately 40% additional methane yields, and was accompanied by a approximately 40% increase in volatile solids reduction. The secondary digestate was found to be enriched in lignin and significantly depleted in cellulose and hemi-cellulose components when compared to primary digestate. Thus, steam pressure disruption treatment rendered lignocellulosic substrates readily accessible to anaerobic digestion bacteria and improved both the kinetics of biogas production and the overall methane yield from MSW. Steam pressure disruption is central to a new anaerobic digestion process approach including sequential digestion stages and integrated energy recovery, to improve process yields, provide cogenerated energy for process needs, and to provide effective reuse and recycling of waste biomass materials.

Anaerobiosis↗